AuxXxilium/linux_dsm_epyc7002
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1ed95e52d9
linux_dsm_epyc7002/arch/x86/kernel
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Andy Lutomirski 1ed95e52d9 x86/vdso: Remove direct HPET access through the vDSO 
Allowing user code to map the HPET is problematic.  HPET
implementations are notoriously buggy, and there are probably many
machines on which even MMIO reads from bogus HPET addresses are
problematic.

We have a report that the Dell Precision M2800 with:

  ACPI: HPET 0x00000000C8FE6238 000038 (v01 DELL   CBX3  01072009 AMI. 00000005)

is either so slow when accessing the HPET or actually hangs in some
regard, causing soft lockups to be reported if users do unexpected
things to the HPET.

The vclock HPET code has also always been a questionable speedup.
Accessing an HPET is exceedingly slow (on the order of several
microseconds), so the added overhead in requiring a syscall to read
the HPET is a small fraction of the total code of accessing it.

To avoid future problems, let's just delete the code entirely.

In the long run, this could actually be a speedup.  Waiman Long as a
patch to optimize the case where multiple CPUs contend for the HPET,
but that won't help unless all the accesses are mediated by the
kernel.

Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Waiman Long <Waiman.Long@hpe.com>
Cc: Waiman Long <waiman.long@hpe.com>
Link: http://lkml.kernel.org/r/d2f90bba98db9905041cff294646d290d378f67a.1460074438.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-13 10:28:34 +02:00
..
acpi Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-24 09:47:32 -07:00
apic Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-24 09:47:32 -07:00
cpu x86/cpu: Add Erratum 88 detection on AMD 2016-04-13 10:20:42 +02:00
fpu Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-24 09:47:32 -07:00
kprobes x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard 2016-02-29 08:35:12 +01:00
.gitignore
alternative.c x86/alternatives: Make optimize_nops() interrupt safe and synced 2015-09-03 21:27:47 +02:00
amd_gart_64.c
amd_nb.c x86/gart: Check for GART support before accessing GART registers 2015-05-06 11:15:53 +02:00
apb_timer.c x86/apb/timer: Use proper mask to modify hotplug action 2016-03-19 13:40:08 +01:00
aperture_64.c param: convert some "on"/"off" users to strtobool 2016-03-17 15:09:34 -07:00
apm_32.c x86: Fix misspellings in comments 2016-02-24 08:44:58 +01:00
asm-offsets_32.c x86/entry/32: Simplify and fix up the SYSENTER stack #DB/NMI fixup 2016-03-10 09:48:14 +01:00
asm-offsets_64.c x86/syscalls: Add syscall entry qualifiers 2016-01-29 09:46:38 +01:00
asm-offsets.c x86/asm-offsets: Remove PARAVIRT_enabled 2016-03-08 14:16:44 +01:00
audit_64.c
bootflag.c x86: don't use module_init for non-modular core bootflag code 2015-06-16 14:12:34 -04:00
check.c Linux 4.2-rc8 2015-08-25 09:59:19 +02:00
cpuid.c new helpers: no_seek_end_llseek{,_size}() 2015-12-23 10:41:31 -05:00
crash_dump_32.c
crash_dump_64.c
crash.c x86/kexec: Remove walk_iomem_res() call with GART type 2016-01-30 09:49:59 +01:00
devicetree.c Replace module_init with equivalent device_initcall in non modules. 2015-07-02 10:30:48 -07:00
doublefault.c
dumpstack_32.c
dumpstack_64.c
dumpstack.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2016-03-19 10:05:34 -07:00
e820.c Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-15 09:32:27 -07:00
early_printk.c x86: Fix misspellings in comments 2016-02-24 08:44:58 +01:00
early-quirks.c Linux 4.4-rc2 2015-11-23 09:04:05 +01:00
espfix_64.c Merge branch 'x86/urgent' into x86/asm, before applying dependent patches 2015-07-31 10:23:35 +02:00
ftrace.c Nothing major this round. Mostly small clean ups and fixes. 2016-03-24 10:52:25 -07:00
head32.c
head64.c Merge branch 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-15 10:02:25 -07:00
head_32.S Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-15 10:45:39 -07:00
head_64.S Merge branch 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-15 10:02:25 -07:00
head.c
hpet.c x86/vdso: Remove direct HPET access through the vDSO 2016-04-13 10:28:34 +02:00
hw_breakpoint.c x86/cpufeature: Remove unused and seldomly used cpu_has_xx macros 2015-12-19 11:49:55 +01:00
i386_ksyms_32.c preempt: Use preempt_schedule_context() as the official tracing preemption point 2015-06-07 15:57:42 +02:00
i8237.c
i8253.c clockevents/drivers/i8253: Migrate to new 'set-state' interface 2015-08-10 11:40:30 +02:00
i8259.c x86/irq: Probe for PIC presence before allocating descs for legacy IRQs 2015-11-07 10:37:37 +01:00
io_delay.c
ioport.c x86/iopl: Fix iopl capability check on Xen PV 2016-03-17 09:49:27 +01:00
irq_32.c genirq: Remove irq argument from irq flow handlers 2015-09-16 15:47:51 +02:00
irq_64.c x86/irq: Drop unlikely before IS_ERR_OR_NULL 2015-10-01 11:08:56 +02:00
irq_work.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
irq.c x86/irq: Call irq_force_move_complete with irq descriptor 2016-01-15 13:44:01 +01:00
irqinit.c x86/irq: Store irq descriptor in vector array 2015-08-06 00:14:59 +02:00
jump_label.c jump_label: Rename JUMP_LABEL_{EN,DIS}ABLE to JUMP_LABEL_{JMP,NOP} 2015-08-03 11:34:12 +02:00
kdebugfs.c
kexec-bzimage64.c x86: Fix misspellings in comments 2016-02-24 08:44:58 +01:00
kgdb.c Merge branch 'x86/cleanups' into x86/urgent 2016-03-17 09:44:57 +01:00
ksysfs.c
kvm.c kvm, rt: change async pagefault code locking for PREEMPT_RT 2016-03-22 16:38:38 +01:00
kvmclock.c x86: Fix misspellings in comments 2016-02-24 08:44:58 +01:00
ldt.c x86/mm: Factor out LDT init from context init 2016-02-18 19:46:31 +01:00
livepatch.c livepatch: Cleanup module page permission changes 2015-12-04 22:51:07 +01:00
machine_kexec_32.c
machine_kexec_64.c kexec: move some memembers and definitions within the scope of CONFIG_KEXEC_FILE 2016-01-20 17:09:18 -08:00
Makefile mm, kasan: stackdepot implementation. Enable stackdepot for SLAB 2016-03-25 16:37:42 -07:00
mcount_64.S x86/ftrace, x86/asm: Kill ftrace_caller_end label 2016-02-17 08:47:22 +01:00
mmconf-fam10h_64.c
module.c
mpparse.c x86/cpufeature: Use enum cpuid_leafs instead of magic numbers 2016-02-01 10:46:48 +01:00
msr.c x86/cpufeature: Carve out X86_FEATURE_* 2016-01-30 11:22:17 +01:00
nmi_selftest.c
nmi.c x86/nmi: Mark 'ignore_nmis' as __read_mostly 2016-03-08 12:48:19 +01:00
paravirt_patch_32.c x86/paravirt: Remove the unused irq_enable_sysexit pv op 2015-11-23 10:48:16 +01:00
paravirt_patch_64.c x86/entry, x86/paravirt: Remove the unused usergs_sysret32 PV op 2015-11-23 10:48:16 +01:00
paravirt-spinlocks.c locking/pvqspinlock: Rename QUEUED_SPINLOCK to QUEUED_SPINLOCKS 2015-05-11 09:52:09 +02:00
paravirt.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-01-11 16:26:03 -08:00
pci-calgary_64.c x86/platform/calgary: Constify cal_chipset_ops structures 2015-11-29 08:50:58 +01:00
pci-dma.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
pci-iommu_table.c
pci-nommu.c
pci-swiotlb.c x86/mm/64: Enable SWIOTLB if system has SRAT memory regions above MAX_DMA32_PFN 2015-12-06 12:46:31 +01:00
pcspeaker.c
perf_regs.c
pmem.c x86, kexec, nvdimm: Use walk_iomem_res_desc() for iomem search 2016-01-30 09:49:59 +01:00
probe_roms.c
process_32.c sched/core, sched/x86: Kill thread_info::saved_preempt_count 2015-10-06 17:08:18 +02:00
process_64.c x86/asm, sched/x86: Rewrite the FS and GS context switch code 2016-04-13 10:20:42 +02:00
process.c Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-15 09:32:27 -07:00
ptrace.c arch/x86/kernel/ptrace.c: Remove unused arg_offs_table 2015-12-29 11:35:34 +01:00
pvclock.c x86/vdso: Remove pvclock fixmap machinery 2015-12-11 08:56:03 +01:00
quirks.c timers/x86/hpet: Type adjustments 2015-10-21 11:17:32 +02:00
reboot_fixups_32.c
reboot.c x86/reboot/quirks: Add iMac10,1 to pci_reboot_dmi_table[] 2016-01-12 12:27:36 +01:00
relocate_kernel_32.S
relocate_kernel_64.S
resource.c
rtc.c x86/paravirt: Prevent rtc_cmos platform device init on PV guests 2015-12-19 21:35:13 +01:00
setup_percpu.c
setup.c Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-20 19:08:56 -07:00
signal_compat.c x86/compat: Move copy_siginfo_*_user32() to signal_compat.c 2015-07-06 15:28:55 +02:00
signal.c x86/signal/64: Re-add support for SS in the 64-bit signal context 2016-02-17 08:32:11 +01:00
smp.c x86/smp: Remove single IPI wrapper 2015-11-05 13:07:54 +01:00
smpboot.c x86/topology: Use total_cpus not nr_cpu_ids for logical packages 2016-03-19 10:26:40 +01:00
stacktrace.c perf: generalize perf_callchain 2016-02-20 00:21:44 -05:00
step.c Merge branch 'x86/urgent' into x86/asm to fix up conflicts and to pick up fixes 2015-08-18 09:39:47 +02:00
sys_x86_64.c
sysfb_efi.c
sysfb_simplefb.c
sysfb.c
tboot.c mm: cleanup *pte_alloc* interfaces 2016-03-17 15:09:34 -07:00
tce_64.c
test_nx.c x86/mm: Always enable CONFIG_DEBUG_RODATA and remove the Kconfig option 2016-02-22 08:51:38 +01:00
test_rodata.c x86/mm: Always enable CONFIG_DEBUG_RODATA and remove the Kconfig option 2016-02-22 08:51:38 +01:00
time.c
tls.c
tls.h
topology.c x86: Drop bogus __ref / __refdata annotations 2015-07-20 18:57:20 +02:00
trace_clock.c x86/asm/tsc: Add rdtsc_ordered() and use it in trivial call sites 2015-07-06 15:23:29 +02:00
tracepoint.c
traps.c Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-15 10:23:56 -07:00
tsc_msr.c
tsc_sync.c x86/asm/tsc/sync: Use rdtsc_ordered() in check_tsc_warp() and drop extra barriers 2015-07-06 15:23:29 +02:00
tsc.c x86/tsc: Prevent NULL pointer deref in calibrate_delay_is_known() 2016-03-18 14:51:06 +01:00
uprobes.c uprobes/x86: Make arch_uretprobe_is_alive(RP_CHECK_CALL) more clever 2015-07-31 10:38:06 +02:00
verify_cpu.S x86/cpufeature: Carve out X86_FEATURE_* 2016-01-30 11:22:17 +01:00
vm86_32.c x86/cpufeature: Replace the old static_cpu_has() with safe variant 2016-01-30 11:22:18 +01:00
vmlinux.lds.S arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections 2016-03-25 16:37:42 -07:00
vsmp_64.c x86: replace __init_or_module with __init in non-modular vsmp_64.c 2015-06-16 14:12:41 -04:00
x86_init.c x86/tsc: Remove unused tsc_pre_init() hook 2015-11-19 11:03:13 +01:00
x8664_ksyms_64.c x86/mm, x86/mce: Add memcpy_mcsafe() 2016-03-08 17:54:38 +01:00