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Dave Hansen 65a7f03f6b x86: fix page fault tracing when KVM guest support enabled 
I noticed on some of my systems that page fault tracing doesn't
work:

	cd /sys/kernel/debug/tracing
	echo 1 > events/exceptions/enable
	cat trace;
	# nothing shows up

I eventually traced it down to CONFIG_KVM_GUEST.  At least in a
KVM VM, enabling that option breaks page fault tracing, and
disabling fixes it.  I tried on some old kernels and this does
not appear to be a regression: it never worked.

There are two page-fault entry functions today.  One when tracing
is on and another when it is off.  The KVM code calls do_page_fault()
directly instead of calling the traced version:

> dotraplinkage void __kprobes
> do_async_page_fault(struct pt_regs *regs, unsigned long
> error_code)
> {
>         enum ctx_state prev_state;
>
>         switch (kvm_read_and_reset_pf_reason()) {
>         default:
>                 do_page_fault(regs, error_code);
>                 break;
>         case KVM_PV_REASON_PAGE_NOT_PRESENT:

I'm also having problems with the page fault tracing on bare
metal (same symptom of no trace output).  I'm unsure if it's
related.

Steven had an alternative to this which has zero overhead when
tracing is off where this includes the standard noops even when
tracing is disabled.  I'm unconvinced that the extra complexity
of his apporach:

	http://lkml.kernel.org/r/20140508194508.561ed220@gandalf.local.home

is worth it, expecially considering that the KVM code is already
making page fault entry slower here.  This solution is
dirt-simple.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
 		2014-05-22 17:47:17 +02:00
..
acpi Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux into pm-cpuidle 2014-04-08 13:25:25 +02:00
apic Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-04-11 11:58:33 -07:00
cpu Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-04-11 11:58:33 -07:00
kprobes Merge branch 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-09-04 08:42:44 -07:00
.gitignore
…
Makefile x86, vdso: Make vsyscall_gtod_data handling x86 generic 2014-03-18 12:51:52 -07:00
alternative.c lockdep, x86/alternatives: Drop ancient lockdep fixup message 2013-09-28 10:09:41 +02:00
amd_gart_64.c x86, mm: use pfn_range_is_mapped() with gart 2012-11-17 11:59:10 -08:00
amd_nb.c A bunch of EDAC updates all over the place: 2014-04-01 13:54:00 -07:00
apb_timer.c intel_mid: Renamed *mrst* to *intel_mid* 2013-10-17 16:40:47 -07:00
aperture_64.c Revert "[PATCH] Insert GART region into resource map" 2014-03-18 14:26:12 -06:00
apm_32.c x86, asmlinkage, apm: Make APM data structure used from assembler visible 2013-08-06 14:20:20 -07:00
asm-offsets.c sched, x86: Provide a per-cpu preempt_count implementation 2013-09-25 14:07:57 +02:00
asm-offsets_32.c x86: Get rid of ->hard_math and all the FPU asm fu 2013-06-06 14:32:04 -07:00
asm-offsets_64.c x86, gdt, hibernate: Store/load GDT for hibernate path. 2013-05-02 11:27:35 -07:00
audit_64.c
…
bootflag.c
…
check.c x86/mm: memblock: switch to use NUMA_NO_NODE 2014-01-21 16:19:47 -08:00
cpuid.c x86, cpuid: Fix CPU hotplug callback registration 2014-03-20 13:43:42 +01:00
crash.c x86, crash: Unify ifdef 2014-03-13 15:32:44 -07:00
crash_dump_32.c
…
crash_dump_64.c
…
devicetree.c Merge remote-tracking branch 'grant/devicetree/next' into for-next 2013-11-07 10:34:46 -06:00
doublefault.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
dumpstack.c x86/dumpstack: Fix printk_address for direct addresses 2013-11-12 21:06:06 +01:00
dumpstack_32.c Merge branch 'x86-threadinfo-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-04-01 10:17:18 -07:00
dumpstack_64.c x86: Fix dumpstack_64 irq stack handling 2014-04-02 11:46:50 -07:00
e820.c x86/mm: memblock: switch to use NUMA_NO_NODE 2014-01-21 16:19:47 -08:00
early-quirks.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-04-11 12:04:15 -07:00
early_printk.c Merge branch 'x86-intel-mid-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-11-12 11:12:22 +09:00
entry_32.S ftrace/x86: Load ftrace_ops in parameter not the variable holding it 2014-01-09 13:24:29 -08:00
entry_64.S ftrace/x86: Load ftrace_ops in parameter not the variable holding it 2014-01-09 13:24:29 -08:00
ftrace.c ftrace/x86: BUG when ftrace recovery fails 2014-03-07 10:06:16 -05:00
head.c x86: Make sure we can boot in the case the BDA contains pure garbage 2013-02-27 13:38:57 -08:00
head32.c intel_mid: Renamed *mrst* to *intel_mid* 2013-10-17 16:40:47 -07:00
head64.c x86, trace: Register exception handler to trace IDT 2013-11-08 14:15:45 -08:00
head_32.S x86: fix compile error due to X86_TRAP_NMI use in asm files 2014-03-07 18:58:40 -08:00
head_64.S x86: fix compile error due to X86_TRAP_NMI use in asm files 2014-03-07 18:58:40 -08:00
hpet.c CPU hotplug notifiers registration fixes for 3.15-rc1 2014-04-07 14:55:46 -07:00
hw_breakpoint.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
i386_ksyms_32.c sched, x86: Optimize the preempt_schedule() call 2013-09-25 14:23:07 +02:00
i387.c x86, fpu: Check tsk_used_math() in kernel_fpu_end() for eager FPU 2014-03-11 12:32:52 -07:00
i8237.c
…
i8253.c
…
i8259.c x86/irq: Correct comment about i8259 initialization 2013-09-04 07:46:04 +02:00
io_delay.c
…
ioport.c x86: get rid of pt_regs argument of iopl(2) 2013-02-03 18:16:24 -05:00
iosf_mbi.c arch: x86: New MailBox support driver for Intel SOC's 2014-01-08 14:36:29 -08:00
irq.c x86/platform/hyperv: Handle VMBUS driver being a module 2014-04-02 09:49:47 +02:00
irq_32.c x86, threadinfo: Redo "x86: Use inline assembler to get sp" 2014-03-10 17:32:01 -07:00
irq_64.c irq: Consolidate do_softirq() arch overriden implementations 2013-10-01 12:53:25 +02:00
irq_work.c x86, asmlinkage: Make all interrupt handlers asmlinkage / __visible 2013-08-06 14:18:23 -07:00
irqinit.c x86/irq: Fix do_IRQ() interrupt warning for cpu hotplug retriggered irqs 2014-01-12 13:13:02 +01:00
jump_label.c x86/jump_label: expect default_nop if static_key gets enabled on boot-up 2013-10-19 19:45:35 -04:00
kdebugfs.c
…
kgdb.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
ksysfs.c x86: ksysfs.c build fix 2014-01-03 14:37:13 +00:00
kvm.c x86: fix page fault tracing when KVM guest support enabled 2014-05-22 17:47:17 +02:00
kvmclock.c kvm: remove redundant registration of BSP's hv_clock area 2014-02-22 15:53:32 +01:00
ldt.c x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels 2014-04-11 10:10:09 -07:00
machine_kexec_32.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
machine_kexec_64.c x86, kaslr: export offset in VMCOREINFO ELF notes 2014-02-25 16:57:47 -08:00
mmconf-fam10h_64.c x86: delete __cpuinit usage from all x86 files 2013-07-14 19:36:56 -04:00
module.c x86, kaslr: fix module lock ordering problem 2014-03-24 10:18:26 -07:00
mpparse.c
…
msr.c x86, msr: Fix CPU hotplug callback registration 2014-03-20 13:43:42 +01:00
nmi.c x86/nmi: Push duration printk() to irq context 2014-02-09 13:17:22 +01:00
nmi_selftest.c
…
paravirt-spinlocks.c x86, ticketlock: Add slowpath logic 2013-08-09 07:54:00 -07:00
paravirt.c x86, paravirt: Remove duplicate definition for DEF_NATIVE 2013-09-04 09:46:43 -07:00
paravirt_patch_32.c
…
paravirt_patch_64.c
…
pci-calgary_64.c x86, calgary: Use 8M TCE table size by default 2014-04-10 19:51:32 -07:00
pci-dma.c x86: dma-mapping: fix GFP_ATOMIC macro usage 2014-02-11 09:40:15 +01:00
pci-iommu_table.c
…
pci-nommu.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
pci-swiotlb.c
…
pcspeaker.c
…
perf_regs.c perf: Fix off by one test in perf_reg_value() 2012-09-19 17:08:40 +02:00
preempt.S sched, x86: Optimize the preempt_schedule() call 2013-09-25 14:23:07 +02:00
probe_roms.c x86/pci/probe_roms: Add missing __iomem annotation to pci_map_biosrom() 2012-09-05 10:52:25 +02:00
process.c sched/idle, x86: Remove redundant cpuidle_idle_call() 2014-02-11 09:58:28 +01:00
process_32.c x86: Keep thread_info on thread stack in x86_32 2014-03-06 16:56:55 -08:00
process_64.c Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-11-14 16:55:56 +09:00
ptrace.c x86: Keep thread_info on thread stack in x86_32 2014-03-06 16:56:55 -08:00
pvclock.c hung_task: add method to reset detector 2013-11-06 09:49:02 +02:00
quirks.c x86/amd/numa: Fix northbridge quirk to assign correct NUMA node 2014-03-14 11:05:36 +01:00
reboot.c x86, reboot: Only use CF9_COND automatically, not CF9 2014-03-05 15:41:15 -08:00
reboot_fixups_32.c
…
relocate_kernel_32.S x86, asm, cleanup: Replace open-coded control register values with symbolic 2013-06-25 16:26:06 -07:00
relocate_kernel_64.S x86, reloc: Use xorl instead of xorq in relocate_kernel_64.S 2013-06-20 21:30:04 -07:00
resource.c
…
rtc.c Merge branch 'x86-intel-mid-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-11-12 11:12:22 +09:00
setup.c Merge branch 'x86-nuke-platforms-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-04-02 13:15:58 -07:00
setup_percpu.c
…
signal.c Merge branch 'x86-smap-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-09-04 11:08:32 -07:00
smp.c x86, asmlinkage: Make all interrupt handlers asmlinkage / __visible 2013-08-06 14:18:23 -07:00
smpboot.c Merge branch 'x86-threadinfo-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-04-01 10:17:18 -07:00
stacktrace.c
…
step.c ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL 2013-01-22 10:08:00 -08:00
sys_x86_64.c x86 get_unmapped_area: Access mmap_legacy_base through mm_struct member 2013-08-22 10:19:35 -07:00
syscall_32.c x86, asmlinkage: Make syscall tables visible 2013-08-06 14:20:18 -07:00
syscall_64.c x86, asmlinkage: Make syscall tables visible 2013-08-06 14:20:18 -07:00
sysfb.c x86: sysfb: move EFI quirks from efifb to sysfb 2013-08-02 16:17:47 -07:00
sysfb_efi.c x86: sysfb: move EFI quirks from efifb to sysfb 2013-08-02 16:17:47 -07:00
sysfb_simplefb.c x86/simplefb: Mark framebuffer mem-resources as IORESOURCE_BUSY to avoid bootup warning 2013-10-03 07:51:11 +02:00
tboot.c x86 / tboot / ACPI: Fail extended mode reduced hardware sleep 2013-07-31 14:25:51 +02:00
tce_64.c
…
test_nx.c
…
test_rodata.c
…
time.c Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-04-01 11:22:57 -07:00
tls.c make SYSCALL_DEFINE<n>-generated wrappers do asmlinkage_protect 2013-03-03 22:58:33 -05:00
tls.h
…
topology.c hotplug, powerpc, x86: Remove cpu_hotplug_driver_lock() 2013-09-30 19:55:51 +02:00
trace_clock.c tracing,x86: Add a TSC trace_clock 2012-11-13 15:48:27 -05:00
tracepoint.c x86: Make sure IDT is page aligned 2013-07-16 15:14:48 -07:00
traps.c x86/traps: Clean up error exception handler definitions 2013-12-12 14:46:42 +01:00
tsc.c Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-04-02 12:26:43 -07:00
tsc_msr.c x86: tsc: Add missing Baytrail frequency to the table 2014-02-19 17:12:24 +01:00
tsc_sync.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
uprobes.c uretprobes/x86: Hijack return address 2013-04-13 15:31:55 +02:00
verify_cpu.S
…
vm86_32.c x86, vm86: fix VM86 syscalls: use SYSCALL_DEFINEx(...) 2013-05-02 20:36:32 -04:00
vmlinux.lds.S x86, vdso: Zero-pad the VVAR page 2014-03-18 12:52:44 -07:00
vsmp_64.c x86, asmlinkage, paravirt: Make paravirt thunks global 2014-01-29 22:17:17 -08:00
vsyscall_64.c CPU hotplug notifiers registration fixes for 3.15-rc1 2014-04-07 14:55:46 -07:00
vsyscall_emu_64.S
…
vsyscall_gtod.c x86, vdso: Add 32 bit VDSO time support for 64 bit kernel 2014-03-18 12:52:41 -07:00
vsyscall_trace.h
…
x86_init.c PCI: Drop "irq" param from *_restore_msi_irqs() 2013-12-13 08:44:30 -07:00
x8664_ksyms_64.c sched, x86: Optimize the preempt_schedule() call 2013-09-25 14:23:07 +02:00
xsave.c x86, xsave: Support eager-only xsave features, add MPX support 2013-12-06 17:17:42 -08:00