- Prepare for Intel's new SERIALIZE instruction
- Enable split-lock debugging on more CPUs
- Add more Intel CPU models
- Optimize stack canary initialization a bit
- Simplify the Spectre logic a bit
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-cpu-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cpu updates from Ingo Molar:
- prepare for Intel's new SERIALIZE instruction
- enable split-lock debugging on more CPUs
- add more Intel CPU models
- optimize stack canary initialization a bit
- simplify the Spectre logic a bit
* tag 'x86-cpu-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/cpu: Refactor sync_core() for readability
x86/cpu: Relocate sync_core() to sync_core.h
x86/cpufeatures: Add enumeration for SERIALIZE instruction
x86/split_lock: Enable the split lock feature on Sapphire Rapids and Alder Lake CPUs
x86/cpu: Add Lakefield, Alder Lake and Rocket Lake models to the to Intel CPU family
x86/stackprotector: Pre-initialize canary for secondary CPUs
x86/speculation: Merge one test in spectre_v2_user_select_mitigation()
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 debug fixlets from Ingo Molnar:
"Improve x86 debuggability: print registers with the same log level as
the backtrace"
* tag 'x86-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/dumpstack: Show registers dump with trace's log level
x86/dumpstack: Add log_lvl to __show_regs()
x86/dumpstack: Add log_lvl to show_iret_regs()
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-cleanups-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cleanups from Ingo Molnar:
"Misc cleanups all around the place"
* tag 'x86-cleanups-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/ioperm: Initialize pointer bitmap with NULL rather than 0
x86: uv: uv_hub.h: Delete duplicated word
x86: cmpxchg_32.h: Delete duplicated word
x86: bootparam.h: Delete duplicated word
x86/mm: Remove the unused mk_kernel_pgd() #define
x86/tsc: Remove unused "US_SCALE" and "NS_SCALE" leftover macros
x86/ioapic: Remove unused "IOAPIC_AUTO" define
x86/mm: Drop unused MAX_PHYSADDR_BITS
x86/msr: Move the F15h MSRs where they belong
x86/idt: Make idt_descr static
initrd: Remove erroneous comment
x86/mm/32: Fix -Wmissing prototypes warnings for init.c
cpu/speculation: Add prototype for cpu_show_srbds()
x86/mm: Fix -Wmissing-prototypes warnings for arch/x86/mm/init.c
x86/asm: Unify __ASSEMBLY__ blocks
x86/cpufeatures: Mark two free bits in word 3
x86/msr: Lift AMD family 0x15 power-specific MSRs
- Improve uclamp performance by using a static key for the fast path
- Add the "sched_util_clamp_min_rt_default" sysctl, to optimize for
better power efficiency of RT tasks on battery powered devices.
(The default is to maximize performance & reduce RT latencies.)
- Improve utime and stime tracking accuracy, which had a fixed boundary
of error, which created larger and larger relative errors as the values
become larger. This is now replaced with more precise arithmetics,
using the new mul_u64_u64_div_u64() helper in math64.h.
- Improve the deadline scheduler, such as making it capacity aware
- Improve frequency-invariant scheduling
- Misc cleanups in energy/power aware scheduling
- Add sched_update_nr_running tracepoint to track changes to nr_running
- Documentation additions and updates
- Misc cleanups and smaller fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- Improve uclamp performance by using a static key for the fast path
- Add the "sched_util_clamp_min_rt_default" sysctl, to optimize for
better power efficiency of RT tasks on battery powered devices.
(The default is to maximize performance & reduce RT latencies.)
- Improve utime and stime tracking accuracy, which had a fixed boundary
of error, which created larger and larger relative errors as the
values become larger. This is now replaced with more precise
arithmetics, using the new mul_u64_u64_div_u64() helper in math64.h.
- Improve the deadline scheduler, such as making it capacity aware
- Improve frequency-invariant scheduling
- Misc cleanups in energy/power aware scheduling
- Add sched_update_nr_running tracepoint to track changes to nr_running
- Documentation additions and updates
- Misc cleanups and smaller fixes
* tag 'sched-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits)
sched/doc: Factorize bits between sched-energy.rst & sched-capacity.rst
sched/doc: Document capacity aware scheduling
sched: Document arch_scale_*_capacity()
arm, arm64: Fix selection of CONFIG_SCHED_THERMAL_PRESSURE
Documentation/sysctl: Document uclamp sysctl knobs
sched/uclamp: Add a new sysctl to control RT default boost value
sched/uclamp: Fix a deadlock when enabling uclamp static key
sched: Remove duplicated tick_nohz_full_enabled() check
sched: Fix a typo in a comment
sched/uclamp: Remove unnecessary mutex_init()
arm, arm64: Select CONFIG_SCHED_THERMAL_PRESSURE
sched: Cleanup SCHED_THERMAL_PRESSURE kconfig entry
arch_topology, sched/core: Cleanup thermal pressure definition
trace/events/sched.h: fix duplicated word
linux/sched/mm.h: drop duplicated words in comments
smp: Fix a potential usage of stale nr_cpus
sched/fair: update_pick_idlest() Select group with lowest group_util when idle_cpus are equal
sched: nohz: stop passing around unused "ticks" parameter.
sched: Better document ttwu()
sched: Add a tracepoint to track rq->nr_running
...
- Add uncore support for Intel Comet Lake
- Add RAPL support for Hygon Fam18h
- Add Intel "IIO stack to PMON mapping" support on Skylake-SP CPUs,
which enumerates per device performance counters via sysfs and enables
the perf stat --iiostat functionality
- Add support for Intel "Architectural LBRs", which generalized the model
specific LBR hardware tracing feature into a model-independent, architected
performance monitoring feature. Usage is mostly seamless to tooling, as the
pre-existing LBR features are kept, but there's a couple of advantages
under the hood, such as faster context-switching, faster LBR reads,
cleaner exposure of LBR features to guest kernels, etc.
( Since architectural LBRs are supported via XSAVE, there's related
changes to the x86 FPU code as well. )
- ftrace/perf updates: Add support to add a text poke event to record changes
to kernel text (i.e. self-modifying code) in order to
support tracers like Intel PT decoding through
jump labels, kprobes and ftrace trampolines.
- Misc cleanups, smaller fixes.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'perf-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf event updates from Ingo Molnar:
"HW support updates:
- Add uncore support for Intel Comet Lake
- Add RAPL support for Hygon Fam18h
- Add Intel "IIO stack to PMON mapping" support on Skylake-SP CPUs,
which enumerates per device performance counters via sysfs and
enables the perf stat --iiostat functionality
- Add support for Intel "Architectural LBRs", which generalized the
model specific LBR hardware tracing feature into a
model-independent, architected performance monitoring feature.
Usage is mostly seamless to tooling, as the pre-existing LBR
features are kept, but there's a couple of advantages under the
hood, such as faster context-switching, faster LBR reads, cleaner
exposure of LBR features to guest kernels, etc.
( Since architectural LBRs are supported via XSAVE, there's related
changes to the x86 FPU code as well. )
ftrace/perf updates:
- Add support to add a text poke event to record changes to kernel
text (i.e. self-modifying code) in order to support tracers like
Intel PT decoding through jump labels, kprobes and ftrace
trampolines.
Misc cleanups, smaller fixes..."
* tag 'perf-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (47 commits)
perf/x86/rapl: Add Hygon Fam18h RAPL support
kprobes: Remove unnecessary module_mutex locking from kprobe_optimizer()
x86/perf: Fix a typo
perf: <linux/perf_event.h>: drop a duplicated word
perf/x86/intel/lbr: Support XSAVES for arch LBR read
perf/x86/intel/lbr: Support XSAVES/XRSTORS for LBR context switch
x86/fpu/xstate: Add helpers for LBR dynamic supervisor feature
x86/fpu/xstate: Support dynamic supervisor feature for LBR
x86/fpu: Use proper mask to replace full instruction mask
perf/x86: Remove task_ctx_size
perf/x86/intel/lbr: Create kmem_cache for the LBR context data
perf/core: Use kmem_cache to allocate the PMU specific data
perf/core: Factor out functions to allocate/free the task_ctx_data
perf/x86/intel/lbr: Support Architectural LBR
perf/x86/intel/lbr: Factor out intel_pmu_store_lbr
perf/x86/intel/lbr: Factor out rdlbr_all() and wrlbr_all()
perf/x86/intel/lbr: Mark the {rd,wr}lbr_{to,from} wrappers __always_inline
perf/x86/intel/lbr: Unify the stored format of LBR information
perf/x86/intel/lbr: Support LBR_CTL
perf/x86: Expose CPUID enumeration bits for arch LBR
...
- LKMM updates: mostly documentation changes, but also some new litmus tests for atomic ops.
- KCSAN updates: the most important change is that GCC 11 now has all fixes in place
to support KCSAN, so GCC support can be enabled again. Also more annotations.
- futex updates: minor cleanups and simplifications
- seqlock updates: merge preparatory changes/cleanups for the 'associated locks' facilities.
- lockdep updates:
- simplify IRQ trace event handling
- add various new debug checks
- simplify header dependencies, split out <linux/lockdep_types.h>, decouple
lockdep from other low level headers some more
- fix NMI handling
- misc cleanups and smaller fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
- LKMM updates: mostly documentation changes, but also some new litmus
tests for atomic ops.
- KCSAN updates: the most important change is that GCC 11 now has all
fixes in place to support KCSAN, so GCC support can be enabled again.
Also more annotations.
- futex updates: minor cleanups and simplifications
- seqlock updates: merge preparatory changes/cleanups for the
'associated locks' facilities.
- lockdep updates:
- simplify IRQ trace event handling
- add various new debug checks
- simplify header dependencies, split out <linux/lockdep_types.h>,
decouple lockdep from other low level headers some more
- fix NMI handling
- misc cleanups and smaller fixes
* tag 'locking-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits)
kcsan: Improve IRQ state trace reporting
lockdep: Refactor IRQ trace events fields into struct
seqlock: lockdep assert non-preemptibility on seqcount_t write
lockdep: Add preemption enabled/disabled assertion APIs
seqlock: Implement raw_seqcount_begin() in terms of raw_read_seqcount()
seqlock: Add kernel-doc for seqcount_t and seqlock_t APIs
seqlock: Reorder seqcount_t and seqlock_t API definitions
seqlock: seqcount_t latch: End read sections with read_seqcount_retry()
seqlock: Properly format kernel-doc code samples
Documentation: locking: Describe seqlock design and usage
locking/qspinlock: Do not include atomic.h from qspinlock_types.h
locking/atomic: Move ATOMIC_INIT into linux/types.h
lockdep: Move list.h inclusion into lockdep.h
locking/lockdep: Fix TRACE_IRQFLAGS vs. NMIs
futex: Remove unused or redundant includes
futex: Consistently use fshared as boolean
futex: Remove needless goto's
futex: Remove put_futex_key()
rwsem: fix commas in initialisation
docs: locking: Replace HTTP links with HTTPS ones
...
that helps the debugging of IRQ affinity logic bugs, and fix a memory leak.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'irq-urgent-2020-08-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull irq fixes from Ingo Molnar:
"Fix a recent IRQ affinities regression, add in a missing debugfs
printout that helps the debugging of IRQ affinity logic bugs, and fix
a memory leak"
* tag 'irq-urgent-2020-08-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
genirq/debugfs: Add missing irqchip flags
genirq/affinity: Make affinity setting if activated opt-in
irqdomain/treewide: Free firmware node after domain removal
Conflicts:
arch/arm/include/asm/percpu.h
As Stephen Rothwell noted, there's a conflict between this commit
in locking/core:
a21ee6055c ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables")
and this fresh upstream commit:
aa54ea903a ("ARM: percpu.h: fix build error")
a21ee6055c is a simpler solution to the dependency problem and doesn't
further increase header hell - so this conflict resolution effectively
reverts aa54ea903a and uses the a21ee6055c solution.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Remove the special handling for multiple floppies in the initrd code.
No one should be using floppies for booting these days. (famous last
words..)
Includes a spelling fix from Colin Ian King <colin.king@canonical.com>.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
0day reported a possible circular locking dependency:
Chain exists of:
&irq_desc_lock_class --> console_owner --> &port_lock_key
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&port_lock_key);
lock(console_owner);
lock(&port_lock_key);
lock(&irq_desc_lock_class);
The reason for this is a printk() in the i8259 interrupt chip driver
which is invoked with the irq descriptor lock held, which reverses the
lock operations vs. printk() from arbitrary contexts.
Switch the printk() to printk_deferred() to avoid that.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/87365abt2v.fsf@nanos.tec.linutronix.de
All instances of ->get() in arch/x86 switched; that might or might
not be worth splitting up. Notes:
* for xstateregs_get() the amount we want to store is determined at
the boot time; see init_xstate_size() and update_regset_xstate_info() for
details. task->thread.fpu.state.xsave ends with a flexible array member and
the amount of data in it depends upon the FPU features supported/enabled.
* fpregs_get() writes slightly less than full ->thread.fpu.state.fsave
(the last word is not copied); we pass the full size of state.fsave and let
membuf_write() trim to the amount declared by regset - __regset_get() will
make sure that the space in buffer is no more than that.
* copy_xstate_to_user() and its helpers are gone now.
* fpregs_soft_get() was getting user_regset_copyout() arguments
wrong. Since "x86: x86 user_regset math_emu" back in 2008... I really
doubt that it's worth splitting out for -stable, though - you need
a 486SX box for that to trigger...
[Kevin's braino fix for copy_xstate_to_kernel() essentially duplicated here]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
John reported that on a RK3288 system the perf per CPU interrupts are all
affine to CPU0 and provided the analysis:
"It looks like what happens is that because the interrupts are not per-CPU
in the hardware, armpmu_request_irq() calls irq_force_affinity() while
the interrupt is deactivated and then request_irq() with IRQF_PERCPU |
IRQF_NOBALANCING.
Now when irq_startup() runs with IRQ_STARTUP_NORMAL, it calls
irq_setup_affinity() which returns early because IRQF_PERCPU and
IRQF_NOBALANCING are set, leaving the interrupt on its original CPU."
This was broken by the recent commit which blocked interrupt affinity
setting in hardware before activation of the interrupt. While this works in
general, it does not work for this particular case. As contrary to the
initial analysis not all interrupt chip drivers implement an activate
callback, the safe cure is to make the deferred interrupt affinity setting
at activation time opt-in.
Implement the necessary core logic and make the two irqchip implementations
for which this is required opt-in. In hindsight this would have been the
right thing to do, but ...
Fixes: baedb87d1b ("genirq/affinity: Handle affinity setting on inactive interrupts correctly")
Reported-by: John Keeping <john@metanate.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Marc Zyngier <maz@kernel.org>
Acked-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/87blk4tzgm.fsf@nanos.tec.linutronix.de
Having sync_core() in processor.h is problematic since it is not possible
to check for hardware capabilities via the *cpu_has() family of macros.
The latter needs the definitions in processor.h.
It also looks more intuitive to relocate the function to sync_core.h.
This changeset does not make changes in functionality.
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/20200727043132.15082-3-ricardo.neri-calderon@linux.intel.com
Resolve conflicts with ongoing lockdep work that fixed the NMI entry code.
Conflicts:
arch/x86/entry/common.c
arch/x86/include/asm/idtentry.h
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add Sapphire Rapids and Alder Lake processors to CPU list to enumerate
and enable the split lock feature.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/1595634320-79689-1-git-send-email-fenghua.yu@intel.com
Replace the x86 variant with the generic version. Provide the relevant
architecture specific helper functions and defines.
Use a temporary define for idtentry_exit_user which will be cleaned up
seperately.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200722220520.494648601@linutronix.de
The noinstr qualifier is to be specified before the return type in the
same way inline is used.
These 2 cases were missed by previous patches.
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20200723161405.852613-1-ira.weiny@intel.com
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Merge v5.8-rc6 into drm-next
I've got a silent conflict + two trees based on fixes to merge.
Fixes a silent merge with amdgpu
Signed-off-by: Dave Airlie <airlied@redhat.com>
Commit 711419e504 ("irqdomain: Add the missing assignment of
domain->fwnode for named fwnode") unintentionally caused a dangling pointer
page fault issue on firmware nodes that were freed after IRQ domain
allocation. Commit e3beca48a4 fixed that dangling pointer issue by only
freeing the firmware node after an IRQ domain allocation failure. That fix
no longer frees the firmware node immediately, but leaves the firmware node
allocated after the domain is removed.
The firmware node must be kept around through irq_domain_remove, but should be
freed it afterwards.
Add the missing free operations after domain removal where where appropriate.
Fixes: e3beca48a4 ("irqdomain/treewide: Keep firmware node unconditionally allocated")
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com> # drivers/pci
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1595363169-7157-1-git-send-email-jonathan.derrick@intel.com
show_trace_log_lvl() provides x86 platform-specific way to unwind
backtrace with a given log level. Unfortunately, registers dump(s) are
not printed with the same log level - instead, KERN_DEFAULT is always
used.
Arista's switches uses quite common setup with rsyslog, where only
urgent messages goes to console (console_log_level=KERN_ERR), everything
else goes into /var/log/ as the console baud-rate often is indecently
slow (9600 bps).
Backtrace dumps without registers printed have proven to be as useful as
morning standups. Furthermore, in order to introduce KERN_UNSUPPRESSED
(which I believe is still the most elegant way to fix raciness of sysrq[1])
the log level should be passed down the stack to register dumping
functions. Besides, there is a potential use-case for printing traces
with KERN_DEBUG level [2] (where registers dump shouldn't appear with
higher log level).
After all preparations are done, provide log_lvl parameter for
show_regs_if_on_stack() and wire up to actual log level used as
an argument for show_trace_log_lvl().
[1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/
[2]: https://lore.kernel.org/linux-doc/20190724170249.9644-1-dima@arista.com/
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Petr Mladek <pmladek@suse.com>
Link: https://lkml.kernel.org/r/20200629144847.492794-4-dima@arista.com
show_trace_log_lvl() provides x86 platform-specific way to unwind
backtrace with a given log level. Unfortunately, registers dump(s) are
not printed with the same log level - instead, KERN_DEFAULT is always
used.
Arista's switches uses quite common setup with rsyslog, where only
urgent messages goes to console (console_log_level=KERN_ERR), everything
else goes into /var/log/ as the console baud-rate often is indecently
slow (9600 bps).
Backtrace dumps without registers printed have proven to be as useful as
morning standups. Furthermore, in order to introduce KERN_UNSUPPRESSED
(which I believe is still the most elegant way to fix raciness of sysrq[1])
the log level should be passed down the stack to register dumping
functions. Besides, there is a potential use-case for printing traces
with KERN_DEBUG level [2] (where registers dump shouldn't appear with
higher log level).
Add log_lvl parameter to __show_regs().
Keep the used log level intact to separate visible change.
[1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/
[2]: https://lore.kernel.org/linux-doc/20190724170249.9644-1-dima@arista.com/
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Petr Mladek <pmladek@suse.com>
Link: https://lkml.kernel.org/r/20200629144847.492794-3-dima@arista.com
show_trace_log_lvl() provides x86 platform-specific way to unwind
backtrace with a given log level. Unfortunately, registers dump(s) are
not printed with the same log level - instead, KERN_DEFAULT is always
used.
Arista's switches uses quite common setup with rsyslog, where only
urgent messages goes to console (console_log_level=KERN_ERR), everything
else goes into /var/log/ as the console baud-rate often is indecently
slow (9600 bps).
Backtrace dumps without registers printed have proven to be as useful as
morning standups. Furthermore, in order to introduce KERN_UNSUPPRESSED
(which I believe is still the most elegant way to fix raciness of sysrq[1])
the log level should be passed down the stack to register dumping
functions. Besides, there is a potential use-case for printing traces
with KERN_DEBUG level [2] (where registers dump shouldn't appear with
higher log level).
Add log_lvl parameter to show_iret_regs() as a preparation to add it
to __show_regs() and show_regs_if_on_stack().
[1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/
[2]: https://lore.kernel.org/linux-doc/20190724170249.9644-1-dima@arista.com/
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Petr Mladek <pmladek@suse.com>
Link: https://lkml.kernel.org/r/20200629144847.492794-2-dima@arista.com
H.J. reported that post 5.7 a segfault of a user space task does not longer
dump the Code bytes when /proc/sys/debug/exception-trace is enabled. It
prints 'Code: Bad RIP value.' instead.
This was broken by a recent change which made probe_kernel_read() reject
non-kernel addresses.
Update show_opcodes() so it retrieves user space opcodes via
copy_from_user_nmi().
Fixes: 98a23609b1 ("maccess: always use strict semantics for probe_kernel_read")
Reported-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/87h7tz306w.fsf@nanos.tec.linutronix.de
If a user task's stack is empty, or if it only has user regs, ORC
reports it as a reliable empty stack. But arch_stack_walk_reliable()
incorrectly treats it as unreliable.
That happens because the only success path for user tasks is inside the
loop, which only iterates on non-empty stacks. Generally, a user task
must end in a user regs frame, but an empty stack is an exception to
that rule.
Thanks to commit 71c9582528 ("x86/unwind/orc: Fix error handling in
__unwind_start()"), unwind_start() now sets state->error appropriately.
So now for both ORC and FP unwinders, unwind_done() and !unwind_error()
always means the end of the stack was successfully reached. So the
success path for kthreads is no longer needed -- it can also be used for
empty user tasks.
Reported-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Link: https://lkml.kernel.org/r/f136a4e5f019219cbc4f4da33b30c2f44fa65b84.1594994374.git.jpoimboe@redhat.com
The ORC unwinder fails to unwind newly forked tasks which haven't yet
run on the CPU. It correctly reads the 'ret_from_fork' instruction
pointer from the stack, but it incorrectly interprets that value as a
call stack address rather than a "signal" one, so the address gets
incorrectly decremented in the call to orc_find(), resulting in bad ORC
data.
Fix it by forcing 'ret_from_fork' frames to be signal frames.
Reported-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Link: https://lkml.kernel.org/r/f91a8778dde8aae7f71884b5df2b16d552040441.1594994374.git.jpoimboe@redhat.com
On x86-32 the idt_table with 256 entries needs only 2048 bytes. It is
page-aligned, but the end of the .bss..page_aligned section is not
guaranteed to be page-aligned.
As a result, objects from other .bss sections may end up on the same 4k
page as the idt_table, and will accidentially get mapped read-only during
boot, causing unexpected page-faults when the kernel writes to them.
This could be worked around by making the objects in the page aligned
sections page sized, but that's wrong.
Explicit sections which store only page aligned objects have an implicit
guarantee that the object is alone in the page in which it is placed. That
works for all objects except the last one. That's inconsistent.
Enforcing page sized objects for these sections would wreckage memory
sanitizers, because the object becomes artificially larger than it should
be and out of bound access becomes legit.
Align the end of the .bss..page_aligned and .data..page_aligned section on
page-size so all objects places in these sections are guaranteed to have
their own page.
[ tglx: Amended changelog ]
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20200721093448.10417-1-joro@8bytes.org
To allow the kernel not to play games with set_fs to call exec
implement kernel_execve. The function kernel_execve takes pointers
into kernel memory and copies the values pointed to onto the new
userspace stack.
The calls with arguments from kernel space of do_execve are replaced
with calls to kernel_execve.
The calls do_execve and do_execveat are made static as there are now
no callers outside of exec.
The comments that mention do_execve are updated to refer to
kernel_execve or execve depending on the circumstances. In addition
to correcting the comments, this makes it easy to grep for do_execve
and verify it is not used.
Inspired-by: https://lkml.kernel.org/r/20200627072704.2447163-1-hch@lst.de
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/87wo365ikj.fsf@x220.int.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This fixes a regression encountered while running the
gdb.base/corefile.exp test in GDB's test suite.
In my testing, the typo prevented the sw_reserved field of struct
fxregs_state from being output to the kernel XSAVES area. Thus the
correct mask corresponding to XCR0 was not present in the core file for
GDB to interrogate, resulting in the following behavior:
[kev@f32-1 gdb]$ ./gdb -q testsuite/outputs/gdb.base/corefile/corefile testsuite/outputs/gdb.base/corefile/corefile.core
Reading symbols from testsuite/outputs/gdb.base/corefile/corefile...
[New LWP 232880]
warning: Unexpected size of section `.reg-xstate/232880' in core file.
With the typo fixed, the test works again as expected.
Signed-off-by: Kevin Buettner <kevinb@redhat.com>
Fixes: 9e46365459 ("copy_xstate_to_kernel(): don't leave parts of destination uninitialized")
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Airlie <airlied@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Fix the I/O bitmap invalidation on XEN PV, which was overlooked in the
recent ioperm/iopl rework. This caused the TSS and XEN's I/O bitmap to
get out of sync.
- Use the proper vectors for HYPERV.
- Make disabling of stack protector for the entry code work with GCC
builds which enable stack protector by default. Removing the option is
not sufficient, it needs an explicit -fno-stack-protector to shut it
off.
- Mark check_user_regs() noinstr as it is called from noinstr code. The
missing annotation causes it to be placed in the text section which
makes it instrumentable.
- Add the missing interrupt disable in exc_alignment_check()
- Fixup a XEN_PV build dependency in the 32bit entry code
- A few fixes to make the Clang integrated assembler happy
- Move EFI stub build to the right place for out of tree builds
- Make prepare_exit_to_usermode() static. It's not longer called from ASM
code.
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Merge tag 'x86-urgent-2020-07-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into master
Pull x86 fixes from Thomas Gleixner:
"A pile of fixes for x86:
- Fix the I/O bitmap invalidation on XEN PV, which was overlooked in
the recent ioperm/iopl rework. This caused the TSS and XEN's I/O
bitmap to get out of sync.
- Use the proper vectors for HYPERV.
- Make disabling of stack protector for the entry code work with GCC
builds which enable stack protector by default. Removing the option
is not sufficient, it needs an explicit -fno-stack-protector to
shut it off.
- Mark check_user_regs() noinstr as it is called from noinstr code.
The missing annotation causes it to be placed in the text section
which makes it instrumentable.
- Add the missing interrupt disable in exc_alignment_check()
- Fixup a XEN_PV build dependency in the 32bit entry code
- A few fixes to make the Clang integrated assembler happy
- Move EFI stub build to the right place for out of tree builds
- Make prepare_exit_to_usermode() static. It's not longer called from
ASM code"
* tag 'x86-urgent-2020-07-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/boot: Don't add the EFI stub to targets
x86/entry: Actually disable stack protector
x86/ioperm: Fix io bitmap invalidation on Xen PV
x86: math-emu: Fix up 'cmp' insn for clang ias
x86/entry: Fix vectors to IDTENTRY_SYSVEC for CONFIG_HYPERV
x86/entry: Add compatibility with IAS
x86/entry/common: Make prepare_exit_to_usermode() static
x86/entry: Mark check_user_regs() noinstr
x86/traps: Disable interrupts in exc_aligment_check()
x86/entry/32: Fix XEN_PV build dependency
tss_invalidate_io_bitmap() wasn't wired up properly through the pvop
machinery, so the TSS and Xen's io bitmap would get out of sync
whenever disabling a valid io bitmap.
Add a new pvop for tss_invalidate_io_bitmap() to fix it.
This is XSA-329.
Fixes: 22fe5b0439 ("x86/ioperm: Move TSS bitmap update to exit to user work")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/d53075590e1f91c19f8af705059d3ff99424c020.1595030016.git.luto@kernel.org
Setting interrupt affinity on inactive interrupts is inconsistent when
hierarchical irq domains are enabled. The core code should just store the
affinity and not call into the irq chip driver for inactive interrupts
because the chip drivers may not be in a state to handle such requests.
X86 has a hacky workaround for that but all other irq chips have not which
causes problems e.g. on GIC V3 ITS.
Instead of adding more ugly hacks all over the place, solve the problem in
the core code. If the affinity is set on an inactive interrupt then:
- Store it in the irq descriptors affinity mask
- Update the effective affinity to reflect that so user space has
a consistent view
- Don't call into the irq chip driver
This is the core equivalent of the X86 workaround and works correctly
because the affinity setting is established in the irq chip when the
interrupt is activated later on.
Note, that this is only effective when hierarchical irq domains are enabled
by the architecture. Doing it unconditionally would break legacy irq chip
implementations.
For hierarchial irq domains this works correctly as none of the drivers can
have a dependency on affinity setting in inactive state by design.
Remove the X86 workaround as it is not longer required.
Fixes: 02edee152d ("x86/apic/vector: Ignore set_affinity call for inactive interrupts")
Reported-by: Ali Saidi <alisaidi@amazon.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Ali Saidi <alisaidi@amazon.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200529015501.15771-1-alisaidi@amazon.com
Link: https://lkml.kernel.org/r/877dv2rv25.fsf@nanos.tec.linutronix.de
In removing UV1 support, efi_have_uv1_memmap is no longer used.
Signed-off-by: Steve Wahl <steve.wahl@hpe.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lkml.kernel.org/r/20200713212955.786177105@hpe.com
Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings
(e.g. "unused variable"). If the compiler thinks it is uninitialized,
either simply initialize the variable or make compiler changes.
In preparation for removing[2] the[3] macro[4], remove all remaining
needless uses with the following script:
git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \
xargs perl -pi -e \
's/\buninitialized_var\(([^\)]+)\)/\1/g;
s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;'
drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid
pathological white-space.
No outstanding warnings were found building allmodconfig with GCC 9.3.0
for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64,
alpha, and m68k.
[1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5
Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB
Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers
Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs
Signed-off-by: Kees Cook <keescook@chromium.org>
Quite some non OF/ACPI users of irqdomains allocate firmware nodes of type
IRQCHIP_FWNODE_NAMED or IRQCHIP_FWNODE_NAMED_ID and free them right after
creating the irqdomain. The only purpose of these FW nodes is to convey
name information. When this was introduced the core code did not store the
pointer to the node in the irqdomain. A recent change stored the firmware
node pointer in irqdomain for other reasons and missed to notice that the
usage sites which do the alloc_fwnode/create_domain/free_fwnode sequence
are broken by this. Storing a dangling pointer is dangerous itself, but in
case that the domain is destroyed later on this leads to a double free.
Remove the freeing of the firmware node after creating the irqdomain from
all affected call sites to cure this.
Fixes: 711419e504 ("irqdomain: Add the missing assignment of domain->fwnode for named fwnode")
Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/873661qakd.fsf@nanos.tec.linutronix.de
While the nmi_enter() users did
trace_hardirqs_{off_prepare,on_finish}() there was no matching
lockdep_hardirqs_*() calls to complete the picture.
Introduce idtentry_{enter,exit}_nmi() to enable proper IRQ state
tracking across the NMIs.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200623083721.216740948@infradead.org
There are cases where a guest tries to switch spinlocks to bare metal
behavior (e.g. by setting "xen_nopvspin" on XEN platform and
"hv_nopvspin" on HYPER_V).
That feature is missed on KVM, add a new parameter "nopvspin" to disable
PV spinlocks for KVM guest.
The new 'nopvspin' parameter will also replace Xen and Hyper-V specific
parameters in future patches.
Define variable nopvsin as global because it will be used in future
patches as above.
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
pr_*() is preferred than printk(KERN_* ...), after change all the print
in arch/x86/kernel/kvm.c will have "kvm-guest: xxx" style.
No functional change.
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This reverts commit 34226b6b70.
Commit 8990cac6e5 ("x86/jump_label: Initialize static branching
early") adds jump_label_init() call in setup_arch() to make static
keys initialized early, so we could use the original simpler code
again.
The similar change for XEN is in commit 090d54bcbc ("Revert
"x86/paravirt: Set up the virt_spin_lock_key after static keys get
initialized"")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In the LBR call stack mode, LBR information is used to reconstruct a
call stack. To get the complete call stack, perf has to save/restore
all LBR registers during a context switch. Due to a large number of the
LBR registers, this process causes a high CPU overhead. To reduce the
CPU overhead during a context switch, use the XSAVES/XRSTORS
instructions.
Every XSAVE area must follow a canonical format: the legacy region, an
XSAVE header and the extended region. Although the LBR information is
only kept in the extended region, a space for the legacy region and
XSAVE header is still required. Add a new dedicated structure for LBR
XSAVES support.
Before enabling XSAVES support, the size of the LBR state has to be
sanity checked, because:
- the size of the software structure is calculated from the max number
of the LBR depth, which is enumerated by the CPUID leaf for Arch LBR.
The size of the LBR state is enumerated by the CPUID leaf for XSAVE
support of Arch LBR. If the values from the two CPUID leaves are not
consistent, it may trigger a buffer overflow. For example, a hypervisor
may unconsciously set inconsistent values for the two emulated CPUID.
- unlike other state components, the size of an LBR state depends on the
max number of LBRs, which may vary from generation to generation.
Expose the function xfeature_size() for the sanity check.
The LBR XSAVES support will be disabled if the size of the LBR state
enumerated by CPUID doesn't match with the size of the software
structure.
The XSAVE instruction requires 64-byte alignment for state buffers. A
new macro is added to reflect the alignment requirement. A 64-byte
aligned kmem_cache is created for architecture LBR.
Currently, the structure for each state component is maintained in
fpu/types.h. The structure for the new LBR state component should be
maintained in the same place. Move structure lbr_entry to fpu/types.h as
well for broader sharing.
Add dedicated lbr_save/lbr_restore functions for LBR XSAVES support,
which invokes the corresponding xstate helpers to XSAVES/XRSTORS LBR
information at the context switch when the call stack mode is enabled.
Since the XSAVES/XRSTORS instructions will be eventually invoked, the
dedicated functions is named with '_xsaves'/'_xrstors' postfix.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Link: https://lkml.kernel.org/r/1593780569-62993-23-git-send-email-kan.liang@linux.intel.com
The perf subsystem will only need to save/restore the LBR state.
However, the existing helpers save all supported supervisor states to a
kernel buffer, which will be unnecessary. Two helpers are introduced to
only save/restore requested dynamic supervisor states. The supervisor
features in XFEATURE_MASK_SUPERVISOR_SUPPORTED and
XFEATURE_MASK_SUPERVISOR_UNSUPPORTED mask cannot be saved/restored using
these helpers.
The helpers will be used in the following patch.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Link: https://lkml.kernel.org/r/1593780569-62993-22-git-send-email-kan.liang@linux.intel.com
Last Branch Records (LBR) registers are used to log taken branches and
other control flows. In perf with call stack mode, LBR information is
used to reconstruct a call stack. To get the complete call stack, perf
has to save/restore all LBR registers during a context switch. Due to
the large number of the LBR registers, e.g., the current platform has
96 LBR registers, this process causes a high CPU overhead. To reduce
the CPU overhead during a context switch, an LBR state component that
contains all the LBR related registers is introduced in hardware. All
LBR registers can be saved/restored together using one XSAVES/XRSTORS
instruction.
However, the kernel should not save/restore the LBR state component at
each context switch, like other state components, because of the
following unique features of LBR:
- The LBR state component only contains valuable information when LBR
is enabled in the perf subsystem, but for most of the time, LBR is
disabled.
- The size of the LBR state component is huge. For the current
platform, it's 808 bytes.
If the kernel saves/restores the LBR state at each context switch, for
most of the time, it is just a waste of space and cycles.
To efficiently support the LBR state component, it is desired to have:
- only context-switch the LBR when the LBR feature is enabled in perf.
- only allocate an LBR-specific XSAVE buffer on demand.
(Besides the LBR state, a legacy region and an XSAVE header have to be
included in the buffer as well. There is a total of (808+576) byte
overhead for the LBR-specific XSAVE buffer. The overhead only happens
when the perf is actively using LBRs. There is still a space-saving,
on average, when it replaces the constant 808 bytes of overhead for
every task, all the time on the systems that support architectural
LBR.)
- be able to use XSAVES/XRSTORS for accessing LBR at run time.
However, the IA32_XSS should not be adjusted at run time.
(The XCR0 | IA32_XSS are used to determine the requested-feature
bitmap (RFBM) of XSAVES.)
A solution, called dynamic supervisor feature, is introduced to address
this issue, which
- does not allocate a buffer in each task->fpu;
- does not save/restore a state component at each context switch;
- sets the bit corresponding to the dynamic supervisor feature in
IA32_XSS at boot time, and avoids setting it at run time.
- dynamically allocates a specific buffer for a state component
on demand, e.g. only allocates LBR-specific XSAVE buffer when LBR is
enabled in perf. (Note: The buffer has to include the LBR state
component, a legacy region and a XSAVE header space.)
(Implemented in a later patch)
- saves/restores a state component on demand, e.g. manually invokes
the XSAVES/XRSTORS instruction to save/restore the LBR state
to/from the buffer when perf is active and a call stack is required.
(Implemented in a later patch)
A new mask XFEATURE_MASK_DYNAMIC and a helper xfeatures_mask_dynamic()
are introduced to indicate the dynamic supervisor feature. For the
systems which support the Architecture LBR, LBR is the only dynamic
supervisor feature for now. For the previous systems, there is no
dynamic supervisor feature available.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Link: https://lkml.kernel.org/r/1593780569-62993-21-git-send-email-kan.liang@linux.intel.com
When saving xstate to a kernel/user XSAVE area with the XSAVE family of
instructions, the current code applies the 'full' instruction mask (-1),
which tries to XSAVE all possible features. This method relies on
hardware to trim 'all possible' down to what is enabled in the
hardware. The code works well for now. However, there will be a
problem, if some features are enabled in hardware, but are not suitable
to be saved into all kernel XSAVE buffers, like task->fpu, due to
performance consideration.
One such example is the Last Branch Records (LBR) state. The LBR state
only contains valuable information when LBR is explicitly enabled by
the perf subsystem, and the size of an LBR state is large (808 bytes
for now). To avoid both CPU overhead and space overhead at each context
switch, the LBR state should not be saved into task->fpu like other
state components. It should be saved/restored on demand when LBR is
enabled in the perf subsystem. Current copy_xregs_to_* will trigger a
buffer overflow for such cases.
Three sites use the '-1' instruction mask which must be updated.
Two are saving/restoring the xstate to/from a kernel-allocated XSAVE
buffer and can use 'xfeatures_mask_all', which will save/restore all of
the features present in a normal task FPU buffer.
The last one saves the register state directly to a user buffer. It
could
also use 'xfeatures_mask_all'. Just as it was with the '-1' argument,
any supervisor states in the mask will be filtered out by the hardware
and not saved to the buffer. But, to be more explicit about what is
expected to be saved, use xfeatures_mask_user() for the instruction
mask.
KVM includes the header file fpu/internal.h. To avoid 'undefined
xfeatures_mask_all' compiling issue, move copy_fpregs_to_fpstate() to
fpu/core.c and export it, because:
- The xfeatures_mask_all is indirectly used via copy_fpregs_to_fpstate()
by KVM. The function which is directly used by other modules should be
exported.
- The copy_fpregs_to_fpstate() is a function, while xfeatures_mask_all
is a variable for the "internal" FPU state. It's safer to export a
function than a variable, which may be implicitly changed by others.
- The copy_fpregs_to_fpstate() is a big function with many checks. The
removal of the inline keyword should not impact the performance.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Link: https://lkml.kernel.org/r/1593780569-62993-20-git-send-email-kan.liang@linux.intel.com
Some Makefiles already pass -fno-stack-protector unconditionally.
For example, arch/arm64/kernel/vdso/Makefile, arch/x86/xen/Makefile.
No problem report so far about hard-coding this option. So, we can
assume all supported compilers know -fno-stack-protector.
GCC 4.8 and Clang support this option (https://godbolt.org/z/_HDGzN)
Get rid of cc-option from -fno-stack-protector.
Remove CONFIG_CC_HAS_STACKPROTECTOR_NONE, which is always 'y'.
Note:
arch/mips/vdso/Makefile adds -fno-stack-protector twice, first
unconditionally, and second conditionally. I removed the second one.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
They were originally called _cond_rcu because they were special versions
with conditional RCU handling. Now they're the standard entry and exit
path, so the _cond_rcu part is just confusing. Drop it.
Also change the signature to make them more extensible and more foolproof.
No functional change -- it's pure refactoring.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/247fc67685263e0b673e1d7f808182d28ff80359.1593795633.git.luto@kernel.org
Using a mutex for "print this warning only once" is so overdesigned as
to be actively offensive to my sensitive stomach.
Just use "pr_info_once()" that already does this, although in a
(harmlessly) racy manner that can in theory cause the message to be
printed twice if more than one CPU races on that "is this the first
time" test.
[ If somebody really cares about that harmless data race (which sounds
very unlikely indeed), that person can trivially fix printk_once() by
using a simple atomic access, preferably with an optimistic non-atomic
test first before even bothering to treat the pointless "make sure it
is _really_ just once" case.
A mutex is most definitely never the right primitive to use for
something like this. ]
Yes, this is a small and meaningless detail in a code path that hardly
matters. But let's keep some code quality standards here, and not
accept outrageously bad code.
Link: https://lore.kernel.org/lkml/CAHk-=wgV9toS7GU3KmNpj8hCS9SeF+A0voHS8F275_mgLhL4Lw@mail.gmail.com/
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Reset MXCSR in kernel_fpu_begin() to prevent using a stale user space
value.
- Prevent writing MSR_TEST_CTRL on CPUs which are not explicitly
whitelisted for split lock detection. Some CPUs which do not support
it crash even when the MSR is written to 0 which is the default value.
- Fix the XEN PV fallout of the entry code rework
- Fix the 32bit fallout of the entry code rework
- Add more selftests to ensure that these entry problems don't come back.
- Disable 16 bit segments on XEN PV. It's not supported because XEN PV
does not implement ESPFIX64
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Merge tag 'x86-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Thomas Gleixner:
"A series of fixes for x86:
- Reset MXCSR in kernel_fpu_begin() to prevent using a stale user
space value.
- Prevent writing MSR_TEST_CTRL on CPUs which are not explicitly
whitelisted for split lock detection. Some CPUs which do not
support it crash even when the MSR is written to 0 which is the
default value.
- Fix the XEN PV fallout of the entry code rework
- Fix the 32bit fallout of the entry code rework
- Add more selftests to ensure that these entry problems don't come
back.
- Disable 16 bit segments on XEN PV. It's not supported because XEN
PV does not implement ESPFIX64"
* tag 'x86-urgent-2020-07-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/ldt: Disable 16-bit segments on Xen PV
x86/entry/32: Fix #MC and #DB wiring on x86_32
x86/entry/xen: Route #DB correctly on Xen PV
x86/entry, selftests: Further improve user entry sanity checks
x86/entry/compat: Clear RAX high bits on Xen PV SYSENTER
selftests/x86: Consolidate and fix get/set_eflags() helpers
selftests/x86/syscall_nt: Clear weird flags after each test
selftests/x86/syscall_nt: Add more flag combinations
x86/entry/64/compat: Fix Xen PV SYSENTER frame setup
x86/entry: Move SYSENTER's regs->sp and regs->flags fixups into C
x86/entry: Assert that syscalls are on the right stack
x86/split_lock: Don't write MSR_TEST_CTRL on CPUs that aren't whitelisted
x86/fpu: Reset MXCSR to default in kernel_fpu_begin()
Now that HAVE_COPY_THREAD_TLS has been removed, rename copy_thread_tls()
back simply copy_thread(). It's a simpler name, and doesn't imply that only
tls is copied here. This finishes an outstanding chunk of internal process
creation work since we've added clone3().
Cc: linux-arch@vger.kernel.org
Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>A
Acked-by: Stafford Horne <shorne@gmail.com>
Acked-by: Greentime Hu <green.hu@gmail.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>A
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Xen PV doesn't implement ESPFIX64, so they don't work right. Disable
them. Also print a warning the first time anyone tries to use a
16-bit segment on a Xen PV guest that would otherwise allow it
to help people diagnose this change in behavior.
This gets us closer to having all x86 selftests pass on Xen PV.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/92b2975459dfe5929ecf34c3896ad920bd9e3f2d.1593795633.git.luto@kernel.org
DEFINE_IDTENTRY_MCE and DEFINE_IDTENTRY_DEBUG were wired up as non-RAW
on x86_32, but the code expected them to be RAW.
Get rid of all the macro indirection for them on 32-bit and just use
DECLARE_IDTENTRY_RAW and DEFINE_IDTENTRY_RAW directly.
Also add a warning to make sure that we only hit the _kernel paths
in kernel mode.
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/9e90a7ee8e72fd757db6d92e1e5ff16339c1ecf9.1593795633.git.luto@kernel.org
On Xen PV, #DB doesn't use IST. It still needs to be correctly routed
depending on whether it came from user or kernel mode.
Get rid of DECLARE/DEFINE_IDTENTRY_XEN -- it was too hard to follow the
logic. Instead, route #DB and NMI through DECLARE/DEFINE_IDTENTRY_RAW on
Xen, and do the right thing for #DB. Also add more warnings to the
exc_debug* handlers to make this type of failure more obvious.
This fixes various forms of corruption that happen when usermode
triggers #DB on Xen PV.
Fixes: 4c0dcd8350 ("x86/entry: Implement user mode C entry points for #DB and #MCE")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/4163e733cce0b41658e252c6c6b3464f33fdff17.1593795633.git.luto@kernel.org
On Xen PV, SWAPGS doesn't work. Teach __rdfsbase_inactive() and
__wrgsbase_inactive() to use rdmsrl()/wrmsrl() on Xen PV. The Xen
pvop code will understand this and issue the correct hypercalls.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/f07c08f178fe9711915862b656722a207cd52c28.1593192140.git.luto@kernel.org
Debuggers expect that doing PTRACE_GETREGS, then poking at a tracee
and maybe letting it run for a while, then doing PTRACE_SETREGS will
put the tracee back where it was. In the specific case of a 32-bit
tracer and tracee, the PTRACE_GETREGS/SETREGS data structure doesn't
have fs_base or gs_base fields, so FSBASE and GSBASE fields are
never stored anywhere. Everything used to still work because
nonzero FS or GS would result full reloads of the segment registers
when the tracee resumes, and the bases associated with FS==0 or
GS==0 are irrelevant to 32-bit code.
Adding FSGSBASE support broke this: when FSGSBASE is enabled, FSBASE
and GSBASE are now restored independently of FS and GS for all tasks
when context-switched in. This means that, if a 32-bit tracer
restores a previous state using PTRACE_SETREGS but the tracee's
pre-restore and post-restore bases don't match, then the tracee is
resumed with the wrong base.
Fix it by explicitly loading the base when a 32-bit tracer pokes FS
or GS on a 64-bit kernel.
Also add a test case.
Fixes: 673903495c ("x86/process/64: Use FSBSBASE in switch_to() if available")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/229cc6a50ecbb701abd50fe4ddaf0eda888898cd.1593192140.git.luto@kernel.org
Choo! Choo! All aboard the Split Lock Express, with direct service to
Wreckage!
Skip split_lock_verify_msr() if the CPU isn't whitelisted as a possible
SLD-enabled CPU model to avoid writing MSR_TEST_CTRL. MSR_TEST_CTRL
exists, and is writable, on many generations of CPUs. Writing the MSR,
even with '0', can result in bizarre, undocumented behavior.
This fixes a crash on Haswell when resuming from suspend with a live KVM
guest. Because APs use the standard SMP boot flow for resume, they will
go through split_lock_init() and the subsequent RDMSR/WRMSR sequence,
which runs even when sld_state==sld_off to ensure SLD is disabled. On
Haswell (at least, my Haswell), writing MSR_TEST_CTRL with '0' will
succeed and _may_ take the SMT _sibling_ out of VMX root mode.
When KVM has an active guest, KVM performs VMXON as part of CPU onlining
(see kvm_starting_cpu()). Because SMP boot is serialized, the resulting
flow is effectively:
on_each_ap_cpu() {
WRMSR(MSR_TEST_CTRL, 0)
VMXON
}
As a result, the WRMSR can disable VMX on a different CPU that has
already done VMXON. This ultimately results in a #UD on VMPTRLD when
KVM regains control and attempt run its vCPUs.
The above voodoo was confirmed by reworking KVM's VMXON flow to write
MSR_TEST_CTRL prior to VMXON, and to serialize the sequence as above.
Further verification of the insanity was done by redoing VMXON on all
APs after the initial WRMSR->VMXON sequence. The additional VMXON,
which should VM-Fail, occasionally succeeded, and also eliminated the
unexpected #UD on VMPTRLD.
The damage done by writing MSR_TEST_CTRL doesn't appear to be limited
to VMX, e.g. after suspend with an active KVM guest, subsequent reboots
almost always hang (even when fudging VMXON), a #UD on a random Jcc was
observed, suspend/resume stability is qualitatively poor, and so on and
so forth.
kernel BUG at arch/x86/kvm/x86.c:386!
CPU: 1 PID: 2592 Comm: CPU 6/KVM Tainted: G D
Hardware name: ASUS Q87M-E/Q87M-E, BIOS 1102 03/03/2014
RIP: 0010:kvm_spurious_fault+0xf/0x20
Call Trace:
vmx_vcpu_load_vmcs+0x1fb/0x2b0
vmx_vcpu_load+0x3e/0x160
kvm_arch_vcpu_load+0x48/0x260
finish_task_switch+0x140/0x260
__schedule+0x460/0x720
_cond_resched+0x2d/0x40
kvm_arch_vcpu_ioctl_run+0x82e/0x1ca0
kvm_vcpu_ioctl+0x363/0x5c0
ksys_ioctl+0x88/0xa0
__x64_sys_ioctl+0x16/0x20
do_syscall_64+0x4c/0x170
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: dbaba47085 ("x86/split_lock: Rework the initialization flow of split lock detection")
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20200605192605.7439-1-sean.j.christopherson@intel.com
When creating a trampoline based on the ftrace_regs_caller code, nop out the
jnz test that would jmup to the code that would return to a direct caller
(stored in the ORIG_RAX field) and not back to the function that called it.
Link: http://lkml.kernel.org/r/20200422162750.638839749@goodmis.org
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
If a direct hook is attached to a function that ftrace also has a function
attached to it, then it is required that the ftrace_ops_list_func() is used
to iterate over the registered ftrace callbacks. This will also include the
direct ftrace_ops helper, that tells ftrace_regs_caller where to return to
(the direct callback and not the function that called it).
As this direct helper is only to handle the case of ftrace callbacks
attached to the same function as the direct callback, the ftrace callback
allocated trampolines (used to only call them), should never be used to
return back to a direct callback.
Only copy the portion of the ftrace_regs_caller that will return back to
what called it, and not the portion that returns back to the direct caller.
The direct ftrace_ops must then pick the ftrace_regs_caller builtin function
as its own trampoline to ensure that it will never have one allocated for
it (which would not include the handling of direct callbacks).
Link: http://lkml.kernel.org/r/20200422162750.495903799@goodmis.org
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
If a direct function is hooked along with one of the ftrace registered
functions, then the ftrace_regs_caller is attached to the function that
shares the direct hook as well as the ftrace hook. The ftrace_regs_caller
will call ftrace_ops_list_func() that iterates through all the registered
ftrace callbacks, and if there's a direct callback attached to that
function, the direct ftrace_ops callback is called to notify that
ftrace_regs_caller to return to the direct caller instead of going back to
the function that called it.
But this is a very uncommon case. Currently, the code has it as the default
case. Modify ftrace_regs_caller to make the default case (the non jump) to
just return normally, and have the jump to the handling of the direct
caller.
Link: http://lkml.kernel.org/r/20200422162750.350373278@goodmis.org
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Previously, kernel floating point code would run with the MXCSR control
register value last set by userland code by the thread that was active
on the CPU core just before kernel call. This could affect calculation
results if rounding mode was changed, or a crash if a FPU/SIMD exception
was unmasked.
Restore MXCSR to the kernel's default value.
[ bp: Carve out from a bigger patch by Petteri, add feature check, add
FNINIT call too (amluto). ]
Signed-off-by: Petteri Aimonen <jpa@git.mail.kapsi.fi>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=207979
Link: https://lkml.kernel.org/r/20200624114646.28953-2-bp@alien8.de
* Use the proper length type in the 32-bit truncate() syscall variant,
by Jiri Slaby.
* Reinit IA32_FEAT_CTL during wakeup to fix the case where after
resume, VMXON would #GP due to VMX not being properly enabled, by Sean
Christopherson.
* Fix a static checker warning in the resctrl code, by Dan Carpenter.
* Add a CR4 pinning mask for bits which cannot change after boot, by
Kees Cook.
* Align the start of the loop of __clear_user() to 16 bytes, to improve
performance on AMD zen1 and zen2 microarchitectures, by Matt Fleming.
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Merge tag 'x86_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Borislav Petkov:
- AMD Memory bandwidth counter width fix, by Babu Moger.
- Use the proper length type in the 32-bit truncate() syscall variant,
by Jiri Slaby.
- Reinit IA32_FEAT_CTL during wakeup to fix the case where after
resume, VMXON would #GP due to VMX not being properly enabled, by
Sean Christopherson.
- Fix a static checker warning in the resctrl code, by Dan Carpenter.
- Add a CR4 pinning mask for bits which cannot change after boot, by
Kees Cook.
- Align the start of the loop of __clear_user() to 16 bytes, to improve
performance on AMD zen1 and zen2 microarchitectures, by Matt Fleming.
* tag 'x86_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/asm/64: Align start of __clear_user() loop to 16-bytes
x86/cpu: Use pinning mask for CR4 bits needing to be 0
x86/resctrl: Fix a NULL vs IS_ERR() static checker warning in rdt_cdp_peer_get()
x86/cpu: Reinitialize IA32_FEAT_CTL MSR on BSP during wakeup
syscalls: Fix offset type of ksys_ftruncate()
x86/resctrl: Fix memory bandwidth counter width for AMD
Catch up with upstream, in particular to get c1e8d7c6a7 ("mmap locking
API: convert mmap_sem comments").
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
vmlinux.o: warning: objtool: exc_invalid_op()+0x47: call to probe_kernel_read() leaves .noinstr.text section
Since we use UD2 as a short-cut for 'CALL __WARN', treat it as such.
Have the bare exception handler do the report_bug() thing.
Fixes: 15a416e8aa ("x86/entry: Treat BUG/WARN as NMI-like entries")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200622114713.GE577403@hirez.programming.kicks-ass.net
vmlinux.o: warning: objtool: fixup_bad_iret()+0x8e: call to memcpy() leaves .noinstr.text section
Worse, when KASAN there is no telling what memcpy() actually is. Force
the use of __memcpy() which is our assmebly implementation.
Reported-by: Marco Elver <elver@google.com>
Suggested-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Marco Elver <elver@google.com>
Link: https://lkml.kernel.org/r/20200618144801.760070502@infradead.org
Add functionality to disable writing to MSRs from userspace. Writes can
still be allowed by supplying the allow_writes=on module parameter. The
kernel will be tainted so that it shows in oopses.
Having unfettered access to all MSRs on a system is and has always been
a disaster waiting to happen. Think performance counter MSRs, MSRs with
sticky or locked bits, MSRs making major system changes like loading
microcode, MTRRs, PAT configuration, TSC counter, security mitigations
MSRs, you name it.
This also destroys all the kernel's caching of MSR values for
performance, as the recent case with MSR_AMD64_LS_CFG showed.
Another example is writing MSRs by mistake by simply typing the wrong
MSR address. System freezes have been experienced that way.
In general, poking at MSRs under the kernel's feet is a bad bad idea.
So log writing to MSRs by default. Longer term, such writes will be
disabled by default.
If userspace still wants to do that, then proper interfaces should be
defined which are under the kernel's control and accesses to those MSRs
can be synchronized and sanitized properly.
[ Fix sparse warnings. ]
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Link: https://lkml.kernel.org/r/20200612105026.GA22660@zn.tnic
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm fixes from Paolo Bonzini:
"All bugfixes except for a couple cleanup patches"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: VMX: Remove vcpu_vmx's defunct copy of host_pkru
KVM: x86: allow TSC to differ by NTP correction bounds without TSC scaling
KVM: X86: Fix MSR range of APIC registers in X2APIC mode
KVM: VMX: Stop context switching MSR_IA32_UMWAIT_CONTROL
KVM: nVMX: Plumb L2 GPA through to PML emulation
KVM: x86/mmu: Avoid mixing gpa_t with gfn_t in walk_addr_generic()
KVM: LAPIC: ensure APIC map is up to date on concurrent update requests
kvm: lapic: fix broken vcpu hotplug
Revert "KVM: VMX: Micro-optimize vmexit time when not exposing PMU"
KVM: VMX: Add helpers to identify interrupt type from intr_info
kvm/svm: disable KCSAN for svm_vcpu_run()
KVM: MIPS: Fix a build error for !CPU_LOONGSON64
Remove support for context switching between the guest's and host's
desired UMWAIT_CONTROL. Propagating the guest's value to hardware isn't
required for correct functionality, e.g. KVM intercepts reads and writes
to the MSR, and the latency effects of the settings controlled by the
MSR are not architecturally visible.
As a general rule, KVM should not allow the guest to control power
management settings unless explicitly enabled by userspace, e.g. see
KVM_CAP_X86_DISABLE_EXITS. E.g. Intel's SDM explicitly states that C0.2
can improve the performance of SMT siblings. A devious guest could
disable C0.2 so as to improve the performance of their workloads at the
detriment to workloads running in the host or on other VMs.
Wholesale removal of UMWAIT_CONTROL context switching also fixes a race
condition where updates from the host may cause KVM to enter the guest
with the incorrect value. Because updates are are propagated to all
CPUs via IPI (SMP function callback), the value in hardware may be
stale with respect to the cached value and KVM could enter the guest
with the wrong value in hardware. As above, the guest can't observe the
bad value, but it's a weird and confusing wart in the implementation.
Removal also fixes the unnecessary usage of VMX's atomic load/store MSR
lists. Using the lists is only necessary for MSRs that are required for
correct functionality immediately upon VM-Enter/VM-Exit, e.g. EFER on
old hardware, or for MSRs that need to-the-uop precision, e.g. perf
related MSRs. For UMWAIT_CONTROL, the effects are only visible in the
kernel via TPAUSE/delay(), and KVM doesn't do any form of delay in
vcpu_vmx_run(). Using the atomic lists is undesirable as they are more
expensive than direct RDMSR/WRMSR.
Furthermore, even if giving the guest control of the MSR is legitimate,
e.g. in pass-through scenarios, it's not clear that the benefits would
outweigh the overhead. E.g. saving and restoring an MSR across a VMX
roundtrip costs ~250 cycles, and if the guest diverged from the host
that cost would be paid on every run of the guest. In other words, if
there is a legitimate use case then it should be enabled by a new
per-VM capability.
Note, KVM still needs to emulate MSR_IA32_UMWAIT_CONTROL so that it can
correctly expose other WAITPKG features to the guest, e.g. TPAUSE,
UMWAIT and UMONITOR.
Fixes: 6e3ba4abce ("KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL")
Cc: stable@vger.kernel.org
Cc: Jingqi Liu <jingqi.liu@intel.com>
Cc: Tao Xu <tao3.xu@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200623005135.10414-1-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This separate helper only existed to guarantee the mutual exclusivity of
CLONE_PIDFD and CLONE_PARENT_SETTID for legacy clone since CLONE_PIDFD
abuses the parent_tid field to return the pidfd. But we can actually handle
this uniformely thus removing the helper. For legacy clone we can detect
that CLONE_PIDFD is specified in conjunction with CLONE_PARENT_SETTID
because they will share the same memory which is invalid and for clone3()
setting the separate pidfd and parent_tid fields to the same memory is
bogus as well. So fold that helper directly into _do_fork() by detecting
this case.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: linux-m68k@lists.linux-m68k.org
Cc: x86@kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
- Have recordmcount work with > 64K sections (to support LTO)
- kprobe RCU fixes
- Correct a kprobe critical section with missing mutex
- Remove redundant arch_disarm_kprobe() call
- Fix lockup when kretprobe triggers within kprobe_flush_task()
- Fix memory leak in fetch_op_data operations
- Fix sleep in atomic in ftrace trace array sample code
- Free up memory on failure in sample trace array code
- Fix incorrect reporting of function_graph fields in format file
- Fix quote within quote parsing in bootconfig
- Fix return value of bootconfig tool
- Add testcases for bootconfig tool
- Fix maybe uninitialized warning in ftrace pid file code
- Remove unused variable in tracing_iter_reset()
- Fix some typos
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Merge tag 'trace-v5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
- Have recordmcount work with > 64K sections (to support LTO)
- kprobe RCU fixes
- Correct a kprobe critical section with missing mutex
- Remove redundant arch_disarm_kprobe() call
- Fix lockup when kretprobe triggers within kprobe_flush_task()
- Fix memory leak in fetch_op_data operations
- Fix sleep in atomic in ftrace trace array sample code
- Free up memory on failure in sample trace array code
- Fix incorrect reporting of function_graph fields in format file
- Fix quote within quote parsing in bootconfig
- Fix return value of bootconfig tool
- Add testcases for bootconfig tool
- Fix maybe uninitialized warning in ftrace pid file code
- Remove unused variable in tracing_iter_reset()
- Fix some typos
* tag 'trace-v5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ftrace: Fix maybe-uninitialized compiler warning
tools/bootconfig: Add testcase for show-command and quotes test
tools/bootconfig: Fix to return 0 if succeeded to show the bootconfig
tools/bootconfig: Fix to use correct quotes for value
proc/bootconfig: Fix to use correct quotes for value
tracing: Remove unused event variable in tracing_iter_reset
tracing/probe: Fix memleak in fetch_op_data operations
trace: Fix typo in allocate_ftrace_ops()'s comment
tracing: Make ftrace packed events have align of 1
sample-trace-array: Remove trace_array 'sample-instance'
sample-trace-array: Fix sleeping function called from invalid context
kretprobe: Prevent triggering kretprobe from within kprobe_flush_task
kprobes: Remove redundant arch_disarm_kprobe() call
kprobes: Fix to protect kick_kprobe_optimizer() by kprobe_mutex
kprobes: Use non RCU traversal APIs on kprobe_tables if possible
kprobes: Suppress the suspicious RCU warning on kprobes
recordmcount: support >64k sections
Commit
3e77abda65 ("x86/idt: Consolidate idt functionality")
states that idt_descr could be made static, but it did not actually make
the change. Make it static now.
Fixes: 3e77abda65 ("x86/idt: Consolidate idt functionality")
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200619205103.30873-1-jandryuk@gmail.com
Now that we've renamed probe_kernel_address() to get_kernel_nofault()
and made it look and behave more in line with get_user(), some of the
subtle type behavior differences end up being more obvious and possibly
dangerous.
When you do
get_user(val, user_ptr);
the type of the access comes from the "user_ptr" part, and the above
basically acts as
val = *user_ptr;
by design (except, of course, for the fact that the actual dereference
is done with a user access).
Note how in the above case, the type of the end result comes from the
pointer argument, and then the value is cast to the type of 'val' as
part of the assignment.
So the type of the pointer is ultimately the more important type both
for the access itself.
But 'get_kernel_nofault()' may now _look_ similar, but it behaves very
differently. When you do
get_kernel_nofault(val, kernel_ptr);
it behaves like
val = *(typeof(val) *)kernel_ptr;
except, of course, for the fact that the actual dereference is done with
exception handling so that a faulting access is suppressed and returned
as the error code.
But note how different the casting behavior of the two superficially
similar accesses are: one does the actual access in the size of the type
the pointer points to, while the other does the access in the size of
the target, and ignores the pointer type entirely.
Actually changing get_kernel_nofault() to act like get_user() is almost
certainly the right thing to do eventually, but in the meantime this
patch adds logit to at least verify that the pointer type is compatible
with the type of the result.
In many cases, this involves just casting the pointer to 'void *' to
make it obvious that the type of the pointer is not the important part.
It's not how 'get_user()' acts, but at least the behavioral difference
is now obvious and explicit.
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Better describe what this helper does, and match the naming of
copy_from_kernel_nofault.
Also switch the argument order around, so that it acts and looks
like get_user().
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The kernel needs to explicitly enable FSGSBASE. So, the application needs
to know if it can safely use these instructions. Just looking at the CPUID
bit is not enough because it may be running in a kernel that does not
enable the instructions.
One way for the application would be to just try and catch the SIGILL.
But that is difficult to do in libraries which may not want to overwrite
the signal handlers of the main application.
Enumerate the enabled FSGSBASE capability in bit 1 of AT_HWCAP2 in the ELF
aux vector. AT_HWCAP2 is already used by PPC for similar purposes.
The application can access it open coded or by using the getauxval()
function in newer versions of glibc.
[ tglx: Massaged changelog ]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1557309753-24073-18-git-send-email-chang.seok.bae@intel.com
Link: https://lkml.kernel.org/r/20200528201402.1708239-14-sashal@kernel.org
Before enabling FSGSBASE the kernel could safely assume that the content
of GS base was a user address. Thus any speculative access as the result
of a mispredicted branch controlling the execution of SWAPGS would be to
a user address. So systems with speculation-proof SMAP did not need to
add additional LFENCE instructions to mitigate.
With FSGSBASE enabled a hostile user can set GS base to a kernel address.
So they can make the kernel speculatively access data they wish to leak
via a side channel. This means that SMAP provides no protection.
Add FSGSBASE as an additional condition to enable the fence-based SWAPGS
mitigation.
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200528201402.1708239-9-sashal@kernel.org
When FSGSBASE is enabled, copying threads and reading fsbase and gsbase
using ptrace must read the actual values.
When copying a thread, use save_fsgs() and copy the saved values. For
ptrace, the bases must be read from memory regardless of the selector if
FSGSBASE is enabled.
[ tglx: Invoke __rdgsbase_inactive() with interrupts disabled ]
[ luto: Massage changelog ]
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1557309753-24073-9-git-send-email-chang.seok.bae@intel.com
Link: https://lkml.kernel.org/r/20200528201402.1708239-8-sashal@kernel.org
With the new FSGSBASE instructions, FS and GSABSE can be efficiently read
and writen in __switch_to(). Use that capability to preserve the full
state.
This will enable user code to do whatever it wants with the new
instructions without any kernel-induced gotchas. (There can still be
architectural gotchas: movl %gs,%eax; movl %eax,%gs may change GSBASE if
WRGSBASE was used, but users are expected to read the CPU manual before
doing things like that.)
This is a considerable speedup. It seems to save about 100 cycles
per context switch compared to the baseline 4.6-rc1 behavior on a
Skylake laptop. This is mostly due to avoiding the WRMSR operation.
[ chang: 5~10% performance improvements were seen with a context switch
benchmark that ran threads with different FS/GSBASE values (to the
baseline 4.16). Minor edit on the changelog. ]
[ tglx: Masaage changelog ]
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Link: https://lkml.kernel.org/r/1557309753-24073-8-git-send-email-chang.seok.bae@intel.com
Link: https://lkml.kernel.org/r/20200528201402.1708239-6-sashal@kernel.org
save_fsgs_for_kvm() is invoked via
vcpu_enter_guest()
kvm_x86_ops.prepare_guest_switch(vcpu)
vmx_prepare_switch_to_guest()
save_fsgs_for_kvm()
with preemption disabled, but interrupts enabled.
The upcoming FSGSBASE based GS safe needs interrupts to be disabled. This
could be done in the helper function, but that function is also called from
switch_to() which has interrupts disabled already.
Disable interrupts inside save_fsgs_for_kvm() and rename the function to
current_save_fsgs() so it can be invoked from other places.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200528201402.1708239-7-sashal@kernel.org
Add cpu feature conditional FSGSBASE access to the relevant helper
functions. That allows to accelerate certain FS/GS base operations in
subsequent changes.
Note, that while possible, the user space entry/exit GSBASE operations are
not going to use the new FSGSBASE instructions. The reason is that it would
require additional storage for the user space value which adds more
complexity to the low level code and experiments have shown marginal
benefit. This may be revisited later but for now the SWAPGS based handling
in the entry code is preserved except for the paranoid entry/exit code.
To preserve the SWAPGS entry mechanism introduce __[rd|wr]gsbase_inactive()
helpers. Note, for Xen PV, paravirt hooks can be added later as they might
allow a very efficient but different implementation.
[ tglx: Massaged changelog, convert it to noinstr and force inline
native_swapgs() ]
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1557309753-24073-7-git-send-email-chang.seok.bae@intel.com
Link: https://lkml.kernel.org/r/20200528201402.1708239-5-sashal@kernel.org
This is temporary. It will allow the next few patches to be tested
incrementally.
Setting unsafe_fsgsbase is a root hole. Don't do it.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/1557309753-24073-4-git-send-email-chang.seok.bae@intel.com
Link: https://lkml.kernel.org/r/20200528201402.1708239-3-sashal@kernel.org
When a ptracer writes a ptracee's FS/GSBASE with a different value, the
selector is also cleared. This behavior is not correct as the selector
should be preserved.
Update only the base value and leave the selector intact. To simplify the
code further remove the conditional checking for the same value as this
code is not performance critical.
The only recognizable downside of this change is when the selector is
already nonzero on write. The base will be reloaded according to the
selector. But the case is highly unexpected in real usages.
[ tglx: Massage changelog ]
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/9040CFCD-74BD-4C17-9A01-B9B713CF6B10@intel.com
Link: https://lkml.kernel.org/r/20200528201402.1708239-2-sashal@kernel.org
Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.
This code was detected with the help of Coccinelle and, audited and
fixed manually.
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20200617211734.GA9636@embeddedor
