force_external_irq_replay() can be called in the do_IRQ path with
interrupts hard enabled and soft disabled if may_hard_irq_enable() set
MSR[EE]=1. It updates local_paca->irq_happened with a load, modify,
store sequence. If a maskable interrupt hits during this sequence, it
will go to the masked handler to be marked pending in irq_happened.
This update will be lost when the interrupt returns and the store
instruction executes. This can result in unpredictable latencies,
timeouts, lockups, etc.
Fix this by ensuring hard interrupts are disabled before modifying
irq_happened.
This could cause any maskable asynchronous interrupt to get lost, but
it was noticed on P9 SMP system doing RDMA NVMe target over 100GbE,
so very high external interrupt rate and high IPI rate. The hang was
bisected down to enabling doorbell interrupts for IPIs. These provided
an interrupt type that could run at high rates in the do_IRQ path,
stressing the race.
Fixes: 1d607bb3bd ("powerpc/irq: Add mechanism to force a replay of interrupts")
Cc: stable@vger.kernel.org # v4.8+
Reported-by: Carol L. Soto <clsoto@us.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
New Kconfig is added "CONFIG_PPC_IRQ_SOFT_MASK_DEBUG" to add WARN_ON
to alert the invalid transitions. Also moved the code under the
CONFIG_TRACE_IRQFLAGS in arch_local_irq_restore() to new Kconfig.
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
[mpe: Fix name of CONFIG option in change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Two new bit mask field "IRQ_DISABLE_MASK_PMU" is introduced to support
the masking of PMI and "IRQ_DISABLE_MASK_ALL" to aid interrupt masking
checking.
Couple of new irq #defs "PACA_IRQ_PMI" and "SOFTEN_VALUE_0xf0*" added
to use in the exception code to check for PMI interrupts.
In the masked_interrupt handler, for PMIs we reset the MSR[EE] and
return. In the __check_irq_replay(), replay the PMI interrupt by
calling performance_monitor_common handler.
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Rename the paca->soft_enabled to paca->irq_soft_mask as it is no
longer used as a flag for interrupt state, but a mask.
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
"paca->soft_enabled" is used as a flag to mask some of interrupts.
Currently supported flags values and their details:
soft_enabled MSR[EE]
0 0 Disabled (PMI and HMI not masked)
1 1 Enabled
"paca->soft_enabled" is initialized to 1 to make the interripts as
enabled. arch_local_irq_disable() will toggle the value when
interrupts needs to disbled. At this point, the interrupts are not
actually disabled, instead, interrupt vector has code to check for the
flag and mask it when it occurs. By "mask it", it update interrupt
paca->irq_happened and return. arch_local_irq_restore() is called to
re-enable interrupts, which checks and replays interrupts if any
occured.
Now, as mentioned, current logic doesnot mask "performance monitoring
interrupts" and PMIs are implemented as NMI. But this patchset depends
on local_irq_* for a successful local_* update. Meaning, mask all
possible interrupts during local_* update and replay them after the
update.
So the idea here is to reserve the "paca->soft_enabled" logic. New
values and details:
soft_enabled MSR[EE]
1 0 Disabled (PMI and HMI not masked)
0 1 Enabled
Reason for the this change is to create foundation for a third mask
value "0x2" for "soft_enabled" to add support to mask PMIs. When
->soft_enabled is set to a value "3", PMI interrupts are mask and when
set to a value of "1", PMI are not mask. With this patch also extends
soft_enabled as interrupt disable mask.
Current flags are renamed from IRQ_[EN?DIS}ABLED to
IRQS_ENABLED and IRQS_DISABLED.
Patch also fixes the ptrace call to force the user to see the softe
value to be alway 1. Reason being, even though userspace has no
business knowing about softe, it is part of pt_regs. Like-wise in
signal context.
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Move set_soft_enabled() from powerpc/kernel/irq.c to asm/hw_irq.c, to
encourage updates to paca->soft_enabled done via these access
function. Add "memory" clobber to hint compiler since
paca->soft_enabled memory is the target here.
Renaming it as soft_enabled_set() will make namespaces works better as
prefix than a postfix when new soft_enabled manipulation functions are
introduced.
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Two #defines IRQS_ENABLED and IRQS_DISABLED are added to be used when
updating paca->soft_enabled. Replace the hardcoded values used when
updating paca->soft_enabled with IRQ_(EN|DIS)ABLED #define. No logic
change.
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When returning from an exception to a soft-enabled context, pending
IRQs are replayed but IRQ tracing is not reset, so a number of them
can get chained together into the same IRQ-disabled trace.
Fix this by having __check_irq_replay re-set IRQ trace. This is
conceptually where we respond to the next interrupt, so it fits the
semantics of the IRQ tracer.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
If the host takes a system reset interrupt while a guest is running,
the CPU must exit the guest before processing the host exception
handler.
After this patch, taking a sysrq+x with a CPU running in a guest
gives a trace like this:
cpu 0x27: Vector: 100 (System Reset) at [c000000fdf5776f0]
pc: c008000010158b80: kvmppc_run_core+0x16b8/0x1ad0 [kvm_hv]
lr: c008000010158b80: kvmppc_run_core+0x16b8/0x1ad0 [kvm_hv]
sp: c000000fdf577850
msr: 9000000002803033
current = 0xc000000fdf4b1e00
paca = 0xc00000000fd4d680 softe: 3 irq_happened: 0x01
pid = 6608, comm = qemu-system-ppc
Linux version 4.14.0-rc7-01489-g47e1893a404a-dirty #26 SMP
[c000000fdf577a00] c008000010159dd4 kvmppc_vcpu_run_hv+0x3dc/0x12d0 [kvm_hv]
[c000000fdf577b30] c0080000100a537c kvmppc_vcpu_run+0x44/0x60 [kvm]
[c000000fdf577b60] c0080000100a1ae0 kvm_arch_vcpu_ioctl_run+0x118/0x310 [kvm]
[c000000fdf577c00] c008000010093e98 kvm_vcpu_ioctl+0x530/0x7c0 [kvm]
[c000000fdf577d50] c000000000357bf8 do_vfs_ioctl+0xd8/0x8c0
[c000000fdf577df0] c000000000358448 SyS_ioctl+0x68/0x100
[c000000fdf577e30] c00000000000b220 system_call+0x58/0x6c
--- Exception: c01 (System Call) at 00007fff76868df0
SP (7fff7069baf0) is in userspace
Fixes: e36d0a2ed5 ("powerpc/powernv: Implement NMI IPI with OPAL_SIGNAL_SYSTEM_RESET")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
It is possible to wake from idle due to a system reset exception, in
which case the CPU takes a system reset interrupt to wake from idle,
with system reset as the wakeup reason.
The regular (not idle wakeup) system reset interrupt handler must be
invoked in this case, otherwise the system reset interrupt is lost.
Handle the system reset interrupt immediately after CPU state has been
restored.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This results in smaller code, and fewer branches. This relies on the
fact that both the 0xe80 and 0xa00 handlers call the same upper level
code, namely doorbell_exception().
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Mention we rely on the implementation of the 0xe80/0xa00 handlers]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Move the clearing of irq_happened bits into the condition where they
were found to be set. This reduces instruction count slightly, and
reduces stores into irq_happened.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
There's a non-trivial dependency between some commits we want to put in
next and the KVM prefetch work around that went into fixes. So merge
fixes into next.
Two config options exist to define powerpc MPC8xx:
* CONFIG_PPC_8xx
* CONFIG_8xx
arch/powerpc/platforms/Kconfig.cputype has contained the following
comment about CONFIG_8xx item for some years:
"# this is temp to handle compat with arch=ppc"
arch/powerpc is now the only place with remaining use of
CONFIG_8xx: get rid of them.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This adds an irq counter for the watchdog soft-NMI. This interrupt
only fires when interrupts are soft-disabled, so it will not
increment much even when the watchdog is running. However it's
useful for debugging and sanity checking.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
If the decrementer wraps again and de-asserts the decrementer
exception while hard-disabled, __check_irq_replay() has a test to
notice the wrap when interrupts are re-enabled.
The decrementer check must be done when clearing the PACA_IRQ_HARD_DIS
flag, not when the PACA_IRQ_DEC flag is tested. Previously this worked
because the decrementer interrupt was always the first one checked
after clearing the hard disable flag, but HMI check was moved ahead of
that, which introduced this bug.
This can cause a missed decrementer interrupt if we soft-disable
interrupts then take an HMI which is recorded in irq_happened, then
hard-disable interrupts for > 4s to wrap the decrementer.
Fixes: e0e0d6b739 ("powerpc/64: Replay hypervisor maintenance interrupt first")
Cc: stable@vger.kernel.org # v4.9+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When the CPU wakes from low power state, it begins at the system reset
interrupt with the exception that caused the wakeup encoded in SRR1.
Today, powernv idle wakeup ignores the wakeup reason (except a special
case for HMI), and the regular interrupt corresponding to the
exception will fire after the idle wakeup exits.
Change this to replay the interrupt from the idle wakeup before
interrupts are hard-enabled.
Test on POWER8 of context_switch selftests benchmark with polling idle
disabled (e.g., always nap, giving cross-CPU IPIs) gives the following
results:
original wakeup direct
Different threads, same core: 315k/s 264k/s
Different cores: 235k/s 242k/s
There is a slowdown for doorbell IPI (same core) case because system
reset wakeup does not clear the message and the doorbell interrupt
fires again needlessly.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This simplifies the asm and fixes irq-off tracing over sleep
instructions.
Also move powersave_nap check for POWER8 into C code, and move
PSSCR register value calculation for POWER9 into C.
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
It often happens to have simultaneous interrupts, for instance
when having double Ethernet attachment. With the current
implementation, we suffer the cost of kernel entry/exit for each
interrupt.
This patch introduces a loop in __do_irq() to handle all interrupts
at once before returning.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This merges the arch part of the XIVE support, leaving the final commit
with the KVM specific pieces dangling on the branch for Paul to merge
via the kvm-ppc tree.
These files don't seem to have any need for asm/debug.h, now that all it
includes are the debugger hooks and breakpoint definitions.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Some powerpc platforms use this to move IRQs away from a CPU being
unplugged. This function has several bugs such as not taking the right
locks or failing to NULL check pointers.
There's a new generic function doing exactly the same thing without all
the bugs, so let's use it instead.
mpe: The obvious place for the select of GENERIC_IRQ_MIGRATION is on
HOTPLUG_CPU, but that doesn't work. On some configs PM_SLEEP_SMP will
select HOTPLUG_CPU even though its dependencies are not met, which means
the select of GENERIC_IRQ_MIGRATION doesn't happen. That leads to the
build breaking. Fix it by moving the select of GENERIC_IRQ_MIGRATION to
SMP.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This was entirely automated, using the script by Al:
PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
$(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)
to do the replacement at the end of the merge window.
Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
NO_IRQ has been == 0 on powerpc for just over ten years (since commit
0ebfff1491 ("[POWERPC] Add new interrupt mapping core and change
platforms to use it")). It's also 0 on most other arches.
Although it's fairly harmless, every now and then it causes confusion
when a driver is built on powerpc and another arch which doesn't define
NO_IRQ. There's at least 6 definitions of NO_IRQ in drivers/, at least
some of which are to work around that problem.
So we'd like to remove it. This is fairly trivial in the arch code, we
just convert:
if (irq == NO_IRQ) to if (!irq)
if (irq != NO_IRQ) to if (irq)
irq = NO_IRQ; to irq = 0;
return NO_IRQ; to return 0;
And a few other odd cases as well.
At least for now we keep the #define NO_IRQ, because there is driver
code that uses NO_IRQ and the fixes to remove those will go via other
trees.
Note we also change some occurrences in PPC sound drivers, drivers/ps3,
and drivers/macintosh.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The HMI (Hypervisor Maintenance Interrupt) is defined by the
architecture to be higher priority than other maskable interrupts, so
replay it first, as a best-effort to replay according to hardware
priorities.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Another set of things that are only called from assembler and so need
prototypes to keep sparse happy.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We plan to use jump label for cpu_has_feature(). In order to implement
this we need to include the linux/jump_label.h in asm/cputable.h.
Unfortunately if we do that it leads to an include loop. The root of the
problem seems to be that reg.h needs cputable.h (for CPU_FTRs), and then
cputable.h via jump_label.h eventually pulls in hw_irq.h which needs
reg.h (for MSR_EE).
So move cpu_has_feature() to a separate file on its own.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
[mpe: Rename to cpu_has_feature.h and flesh out change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Calling this function with interrupts soft-disabled will cause
a replay of the external interrupt vector when they are re-enabled.
This will be used by the OPAL XICS backend (and latter by the native
XIVE code) to handle EOI signaling that there are more interrupts to
fetch from the hardware since the hardware won't issue another HW
interrupt in that case.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
In order to support live patching we need to maintain an alternate
stack of TOC & LR values. We use the base of the stack for this, and
store the "live patch stack pointer" in struct thread_info.
Unlike the other fields of thread_info, we can not statically initialise
that value, so it must be done at run time.
This patch just adds the code to support that, it is not enabled until
the next patch which actually adds live patch support.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Lots of places included bootmem.h even when not using bootmem.
Signed-off-by: Anton Blanchard <anton@samba.org>
Tested-by: Emil Medve <Emilian.Medve@Freescale.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This still has not been merged and now powerpc is the only arch that does
not have this change. Sorry about missing linuxppc-dev before.
V2->V2
- Fix up to work against 3.18-rc1
__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &__get_cpu_var(x). This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.
Other use cases are for storing and retrieving data from the current
processors percpu area. __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.
__get_cpu_var() is defined as :
__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.
this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.
This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset. Thereby address calculations are avoided and less registers
are used when code is generated.
At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.
The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e. using a global
register that may be set to the per cpu base.
Transformations done to __get_cpu_var()
1. Determine the address of the percpu instance of the current processor.
DEFINE_PER_CPU(int, y);
int *x = &__get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(&y);
2. Same as #1 but this time an array structure is involved.
DEFINE_PER_CPU(int, y[20]);
int *x = __get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(y);
3. Retrieve the content of the current processors instance of a per cpu
variable.
DEFINE_PER_CPU(int, y);
int x = __get_cpu_var(y)
Converts to
int x = __this_cpu_read(y);
4. Retrieve the content of a percpu struct
DEFINE_PER_CPU(struct mystruct, y);
struct mystruct x = __get_cpu_var(y);
Converts to
memcpy(&x, this_cpu_ptr(&y), sizeof(x));
5. Assignment to a per cpu variable
DEFINE_PER_CPU(int, y)
__get_cpu_var(y) = x;
Converts to
__this_cpu_write(y, x);
6. Increment/Decrement etc of a per cpu variable
DEFINE_PER_CPU(int, y);
__get_cpu_var(y)++
Converts to
__this_cpu_inc(y)
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
Signed-off-by: Christoph Lameter <cl@linux.com>
[mpe: Fix build errors caused by set/or_softirq_pending(), and rework
assignment in __set_breakpoint() to use memcpy().]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Michael points out that __get_SP() is a pretty horrible
function name. Let's give it a better name.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Add printk levels to some places in the powerpc port.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Handle Hypervisor Maintenance Interrupt (HMI) in Linux. This patch implements
basic infrastructure to handle HMI in Linux host. The design is to invoke
opal handle hmi in real mode for recovery and set irq_pending when we hit HMI.
During check_irq_replay pull opal hmi event and print hmi info on console.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
As of commit 799fef0612 ("powerpc: Use generic idle loop"), this
applies to arch_cpu_idle() instead of cpu_idle().
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
No functional change
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: ppc <linuxppc-dev@lists.ozlabs.org>
Link: http://lkml.kernel.org/r/20140223212736.333718121@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We would allocate one specific exception stack for each kind of
non-base exceptions for every CPU. For ppc32 the CPU hard ID is
used as the subscript to get the specific exception stack for
one CPU. But for an UP kernel, there is only one element in the
each kind of exception stack array. We would get stuck if the
CPU hard ID is not equal to '0'. So in this case we should use the
subscript '0' no matter what the CPU hard ID is.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Current irq_stat.timers_irqs counting doesn't discriminate timer event handler
and other timer interrupt(like arch_irq_work_raise). Sometimes we need to know
exactly how much interrupts timer event handler fired, so let's be more specific
on this.
Signed-off-by: Fan Du <fan.du@windriver.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Pull IRQ changes from Ingo Molnar:
"The biggest change this cycle are the softirq/hardirq stack
interaction and nesting fixes, cleanups and reorganizations from
Frederic. This is the longer followup story to the softirq nesting
fix that is already upstream (commit ded7975475: "irq: Force hardirq
exit's softirq processing on its own stack")"
* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
irqchip: bcm2835: Convert to use IRQCHIP_DECLARE macro
powerpc: Tell about irq stack coverage
x86: Tell about irq stack coverage
irq: Optimize softirq stack selection in irq exit
irq: Justify the various softirq stack choices
irq: Improve a bit softirq debugging
irq: Optimize call to softirq on hardirq exit
irq: Consolidate do_softirq() arch overriden implementations
x86/irq: Correct comment about i8259 initialization
irq_exit() is now called on the irq stack, which can trigger a switch to
the softirq stack from the irq stack. If an interrupt happens at that
point, we will not properly detect the re-entrancy and clobber the
original return context on the irq stack.
This fixes it. The side effect is to prevent all nesting from softirq
stack to irq stack even in the "safe" case but it's simpler that way and
matches what x86_64 does.
Reported-by: Cédric Le Goater <clg@fr.ibm.com>
Tested-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All arch overriden implementations of do_softirq() share the following
common code: disable irqs (to avoid races with the pending check),
check if there are softirqs pending, then execute __do_softirq() on
a specific stack.
Consolidate the common parts such that archs only worry about the
stack switch.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
We've been keeping that field in thread_struct for a while, it contains
the "limit" of the current stack pointer and is meant to be used for
detecting stack overflows.
It has a few problems however:
- First, it was never actually *used* on 64-bit. Set and updated but
not actually exploited
- When switching stack to/from irq and softirq stacks, it's update
is racy unless we hard disable interrupts, which is costly. This
is fine on 32-bit as we don't soft-disable there but not on 64-bit.
Thus rather than fixing 2 in order to implement 1 in some hypothetical
future, let's remove the code completely from 64-bit. In order to avoid
a clutter of ifdef's, we remove the updates from C code completely
during interrupt stack switching, and instead maintain it from the
asm helper that is used to do the stack switching in the first place.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Nowadays, irq_exit() calls __do_softirq() pretty much directly
instead of calling do_softirq() which switches to the decicated
softirq stack.
This has lead to observed stack overflows on powerpc since we call
irq_enter() and irq_exit() outside of the scope that switches to
the irq stack.
This fixes it by moving the stack switching up a level, making
irq_enter() and irq_exit() run off the irq stack.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Back in commit 89713ed "Add timer, performance monitor and machine check
counts to /proc/interrupts" we added a count of PMU interrupts to the
output of /proc/interrupts.
At the time we named them "CNT" to match x86.
However in commit 89ccf46 "Rename 'performance counter interrupt'", the
x86 guys renamed theirs from "CNT" to "PMI".
Arguably changing the name could break someone's script, but I think the
chance of that is minimal, and it's preferable to have a name that 1) is
somewhat meaningful, and 2) matches x86.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Merge tag 'v3.10' into next
Merge 3.10 in order to get some of the last minute powerpc
changes, resolve conflicts and add additional fixes on top
of them.
Previously in order to handle the edge sensitive decrementers,
we choose to set the decrementer to 1 to trigger a decrementer
interrupt when re-enabling interrupts. But with the rework of the
lazy EE, we would replay the decrementer interrupt when re-enabling
interrupts if a decrementer interrupt occurs with irq soft-disabled.
So there is no need to trigger a decrementer interrupt in this case
any more.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
