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Frederic Weisbecker b625b3b3b7 x86: Fixup wrong debug exception frame link in stacktraces 
While dumping a stacktrace, the end of the exception stack won't link
the frame pointer to the previous stack.

The interrupted stack will then be considered as unreliable and ignored
by perf, as the frame pointer is unreliable itself.

This happens because we overwrite the frame pointer that links to the
interrupted frame with the address of the exception stack. This is
done in order to reserve space inside.
But rbp has been chosen here only because it is not a scratch register,
so that the address of the exception stack remains in rbp after calling
do_debug(), we can then release the exception stack space without the
need to retrieve its address again.

But we can pick another non-scratch register to do that, so that we
preserve the link to the interrupted stack frame in the stacktraces.

Just randomly choose r12. Every registers are saved just before and
restored just after calling do_debug(). And r12 is not used in the
middle, which makes it a perfect candidate.

Example: perf record -g -a -c 1 -f -e mem:$(tasklist_lock_addr):rw

Before:
    44.18%  [k] _raw_read_lock
            |
            |
            ---  |--6.31%-- waitid
                 |
                 |--4.26%-- writev
                 |
                 |--3.63%-- __select
                 |
                 |--3.15%-- __waitpid
                 |          |
                 |          |--28.57%-- 0x8b52e00000139f
                 |          |
                 |          |--28.57%-- 0x8b52e0000013c6
                 |          |
                 |          |--14.29%-- 0x7fde786dc000
                 |          |
                 |          |--14.29%-- 0x62696c2f7273752f
                 |          |
                 |           --14.29%-- 0x1ea9df800000000
                 |
                 |--3.00%-- __poll

After:

    43.94%  [k] _raw_read_lock
            |
            --- _read_lock
               |
               |--60.53%-- send_sigio
               |          __kill_fasync
               |          kill_fasync
               |          evdev_pass_event
               |          evdev_event
               |          input_pass_event
               |          input_handle_event
               |          input_event
               |          synaptics_process_byte
               |          psmouse_handle_byte
               |          psmouse_interrupt
               |          serio_interrupt
               |          i8042_interrupt
               |          handle_IRQ_event
               |          handle_edge_irq
               |          handle_irq
               |          __irqentry_text_start
               |          ret_from_intr
               |          |
               |          |--30.43%-- __select
               |          |
               |          |--17.39%-- 0x454f15
               |          |
               |          |--13.04%-- __read
               |          |
               |          |--13.04%-- vread_hpet
               |          |
               |          |--13.04%-- _xcb_lock_io
               |          |
               |           --13.04%-- 0x7f630878ce87

Note: it does not only affect perf events but also other stacktraces in
x86-64. They were considered as unreliable once we quit the debug
stack frame.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: "K. Prasad" <prasad@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
2009-12-06 08:27:22 +01:00
..
acpi x86: Document linker script ASSERT() quirk 2009-10-16 07:18:46 +02:00
apic x86, UV: Fix information in __uv_hub_info structure 2009-10-16 08:18:34 +02:00
cpu x86/perf: Exclude the debug stack from the callchains 2009-12-06 08:27:21 +01:00
.gitignore
alternative.c Merge branch 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-14 07:57:32 -07:00
amd_iommu_init.c Merge branches 'amd-iommu/fixes' and 'dma-debug/fixes' into iommu/fixes 2009-11-03 12:05:40 +01:00
amd_iommu.c Merge branches 'amd-iommu/fixes' and 'dma-debug/fixes' into iommu/fixes 2009-11-03 12:05:40 +01:00
aperture_64.c kmemleak: Ignore the aperture memory hole on x86_64 2009-09-01 11:12:32 +01:00
apm_32.c Merge commit 'origin/x86/urgent' into x86/asm 2009-08-25 15:40:29 -07:00
asm-offsets_32.c lguest: optimize by coding restore_flags and irq_enable in assembler. 2009-06-12 22:27:03 +09:30
asm-offsets_64.c tracing: Define NR_syscalls for x86_64 2009-08-26 21:29:58 +02:00
asm-offsets.c
audit_64.c
bios_uv.c x86, UV: system table in bios accessed after unmap 2009-04-03 19:25:57 +02:00
bootflag.c
check.c x86: fix 64k corruption-check 2009-03-15 07:03:15 +01:00
cpuid.c Driver-Core: extend devnode callbacks to provide permissions 2009-09-19 12:50:38 -07:00
crash_dump_32.c x86: crash_dump: Fix non-pae kdump kernel memory accesses 2009-10-26 12:38:59 +01:00
crash_dump_64.c
crash.c x86: disable IOMMUs on kernel crash 2009-06-15 15:20:40 +02:00
doublefault_32.c x86: Use get_desc_base() 2009-07-19 18:27:51 +02:00
ds_selftest.c x86, ds: fix buffer alignment in debug store selftest 2009-04-24 10:18:51 +02:00
ds_selftest.h x86, bts: cleanups 2009-03-13 11:57:22 +01:00
ds.c x86: ds.c fix invalid assignment 2009-06-20 17:53:13 +02:00
dumpstack_32.c headers: utsname.h redux 2009-09-23 18:13:10 -07:00
dumpstack_64.c headers: utsname.h redux 2009-09-23 18:13:10 -07:00
dumpstack.c x86: Remove duplicated #include 2009-07-11 10:17:08 +02:00
dumpstack.h x86: avoid multiple declaration of kstack_depth_to_print 2009-04-14 11:45:33 +02:00
e820.c pci: increase alignment to make more space for hidden code 2009-10-11 14:43:36 -07:00
early_printk.c x86: earlyprintk: Fix regression to handle serial,ttySn as 1 arg 2009-10-01 10:34:16 +02:00
early-quirks.c x86 early quirks: eliminate unused function 2009-04-08 14:16:32 +02:00
efi_32.c
efi_64.c x86: Make 64-bit efi_ioremap use ioremap on MMIO regions 2009-08-03 13:34:25 -07:00
efi_stub_32.S Merge branch 'x86/asm' into x86/mm 2009-02-25 08:27:46 +01:00
efi_stub_64.S x86: efi_stub_32,64 - add missing ENDPROCs 2009-02-24 18:08:40 +01:00
efi.c x86: Make EFI RTC function depend on 32bit again 2009-10-27 12:35:48 +01:00
entry_32.S Merge branch 'perf/core' into perf/probes 2009-10-23 08:23:20 +02:00
entry_64.S x86: Fixup wrong debug exception frame link in stacktraces 2009-12-06 08:27:22 +01:00
ftrace.c tracing: Move syscalls metadata handling from arch to core 2009-10-14 09:53:56 +02:00
geode_32.c
head32.c x86: Add Moorestown early detection 2009-08-31 11:09:40 +02:00
head64.c x86: Add early platform detection 2009-08-31 11:09:40 +02:00
head_32.S Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-26 10:13:35 -07:00
head_64.S Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-26 10:13:35 -07:00
head.c
hpet.c x86: hpet: Mark per cpu interrupts IRQF_TIMER to prevent resume failure 2009-06-14 18:24:29 +02:00
hw_breakpoint.c hw-breakpoints: Use overflow handler instead of the event callback 2009-12-06 08:27:18 +01:00
i386_ksyms_32.c x86: Don't generate cmpxchg8b_emu if CONFIG_X86_CMPXCHG64=y 2009-10-01 08:42:24 +02:00
i387.c x86, math-emu: fix init_fpu for task != current 2009-03-04 20:33:16 +01:00
i8237.c
i8253.c x86: Do not unregister PIT clocksource on PIT oneshot setup/shutdown 2009-08-21 21:13:37 +02:00
i8259.c x86: refactor x86_quirks support 2009-02-23 00:08:11 +01:00
init_task.c Use new __init_task_data macro in arch init_task.c files. 2009-09-21 06:27:08 +02:00
io_delay.c x86: io_delay.c cleanup 2009-03-21 16:57:04 +05:30
ioport.c x86-32: use non-lazy io bitmap context switching 2009-03-02 12:07:48 +01:00
irq_32.c x86: Use printk_once() 2009-08-09 22:28:34 +02:00
irq_64.c
irq.c x86: Tighten conditionals on MCE related statistics 2009-11-23 19:40:06 +01:00
irqinit.c perf: Do the big rename: Performance Counters -> Performance Events 2009-09-21 14:28:04 +02:00
k8.c
kdebugfs.c x86: kdebugfs.c cleanup 2009-03-21 16:55:45 +05:30
kgdb.c Merge branch 'linus' into tracing/hw-breakpoints 2009-06-17 12:56:49 +02:00
kprobes.c Merge branch 'tracing/hw-breakpoints' into perf/core 2009-11-21 14:07:23 +01:00
kvm.c KVM guest: do not batch pte updates from interrupt context 2009-09-10 18:10:50 +03:00
kvmclock.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-18 14:05:47 -07:00
ldt.c cpumask: use mm_cpumask() wrapper: x86 2009-09-24 09:34:52 +09:30
machine_kexec_32.c hw-breakpoints: cleanup HW Breakpoint registers before kexec 2009-06-02 22:47:00 +02:00
machine_kexec_64.c hw-breakpoints: cleanup HW Breakpoint registers before kexec 2009-06-02 22:47:00 +02:00
Makefile Merge commit 'perf/core' into perf/hw-breakpoint 2009-10-18 01:12:33 +02:00
mca_32.c x86: refactor x86_quirks support 2009-02-23 00:08:11 +01:00
mfgpt_32.c x86: geode: Mark mfgpt irq IRQF_TIMER to prevent resume failure 2009-07-24 08:42:52 +02:00
microcode_amd.c x86, amd-ucode: Check UCODE_MAGIC before loading the container file 2009-11-10 05:46:09 +01:00
microcode_core.c mm: replace various uses of num_physpages by totalram_pages 2009-09-22 07:17:38 -07:00
microcode_intel.c x86: microcode: use smp_call_function_single instead of set_cpus_allowed, cleanup of synchronization logic 2009-05-12 10:36:44 +02:00
mmconf-fam10h_64.c x86: move various CPU initialization objects into .cpuinit.rodata 2009-03-12 13:13:07 +01:00
module.c module: cleanup FIXME comments about trimming exception table entries. 2009-06-12 21:47:05 +09:30
mpparse.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-18 14:05:47 -07:00
mrst.c x86: Add Moorestown early detection 2009-08-31 11:09:40 +02:00
msr.c Driver-Core: extend devnode callbacks to provide permissions 2009-09-19 12:50:38 -07:00
olpc.c
paravirt_patch_32.c
paravirt_patch_64.c
paravirt-spinlocks.c
paravirt.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-18 14:05:47 -07:00
pci-calgary_64.c x86: calgary: remove IOMMU_DEBUG 2009-04-14 13:03:36 +02:00
pci-dma.c x86/PCI: Adjust GFP mask handling for coherent allocations 2009-11-08 07:44:30 -08:00
pci-gart_64.c headers: remove sched.h from interrupt.h 2009-10-11 11:20:58 -07:00
pci-nommu.c dma-ops: Remove flush_write_buffers() in dma-mapping-common.h 2009-08-10 09:34:57 +02:00
pci-swiotlb.c Merge git://git.infradead.org/iommu-2.6 2009-09-23 10:06:10 -07:00
pcspeaker.c
pmtimer_64.c
probe_roms_32.c
process_32.c hw-breakpoints: Rewrite the hw-breakpoints layer on top of perf events 2009-11-08 15:34:42 +01:00
process_64.c Merge branch 'tracing/hw-breakpoints' into perf/core 2009-11-21 14:07:23 +01:00
process.c hw-breakpoints: Rewrite the hw-breakpoints layer on top of perf events 2009-11-08 15:34:42 +01:00
ptrace.c hw-breakpoints: Use overflow handler instead of the event callback 2009-12-06 08:27:18 +01:00
pvclock.c x86: Fix warning in pvclock.c 2009-07-14 16:25:05 +02:00
quirks.c x86/PCI: pci quirks, fix pci refcounting 2009-09-09 14:11:02 -07:00
reboot_fixups_32.c
reboot.c x86: Add reboot quirk for 3 series Mac mini 2009-11-02 15:46:17 +01:00
relocate_kernel_32.S x86, kexec: fix kexec x86 coding style 2009-03-10 18:13:25 -07:00
relocate_kernel_64.S x86, kexec: x86_64: add kexec jump support for x86_64 2009-03-10 18:13:25 -07:00
rtc.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-18 14:05:47 -07:00
scx200_32.c
setup_percpu.c x86,percpu: use embedding for 64bit NUMA and page for 32bit NUMA 2009-08-14 15:00:52 +09:00
setup.c Merge branch 'perf/mce' into perf/core 2009-12-03 20:11:06 +01:00
sfi.c SFI: remove unneeded includes 2009-09-15 15:08:40 -04:00
signal.c Merge commit 'perf/core' into perf/hw-breakpoint 2009-10-18 01:12:33 +02:00
smp.c Revert "x86, timers: Check for pending timers after (device) interrupts" 2009-10-09 15:58:20 +02:00
smpboot.c hw-breakpoints: Rewrite the hw-breakpoints layer on top of perf events 2009-11-08 15:34:42 +01:00
stacktrace.c x86: add save_stack_trace_bp() for tracing from a specific stack frame 2009-06-12 23:01:05 +02:00
step.c x86: Use get_desc_base() 2009-07-19 18:27:51 +02:00
sys_i386_32.c
sys_x86_64.c tracing: Convert x86_64 mmap and uname to use DEFINE_SYSCALL 2009-08-11 20:35:29 +02:00
syscall_64.c
syscall_table_32.S perf: Do the big rename: Performance Counters -> Performance Events 2009-09-21 14:28:04 +02:00
tboot.c x86, intel_txt: clean up the impact on generic code, unbreak non-x86 2009-09-01 18:25:07 -07:00
tce_64.c
test_nx.c
test_rodata.c
time.c x86: fix kernel panic on 32 bits when profiling 2009-10-12 11:53:51 -07:00
tlb_uv.c x86, UV: Fix and clean up bau code to use uv_gpa_to_pnode() 2009-10-16 14:51:53 +02:00
tls.c
tls.h
topology.c x86: topology.c cleanup 2009-03-21 16:55:24 +05:30
trampoline_32.S x86: cpuinit-annotate SMP boot trampolines properly 2009-09-20 20:23:37 +02:00
trampoline_64.S x86: Fix Suspend to RAM freeze on Acer Aspire 1511Lmi laptop 2009-10-12 18:06:48 +02:00
trampoline.c x86: Fix Suspend to RAM freeze on Acer Aspire 1511Lmi laptop 2009-10-12 18:06:48 +02:00
traps.c Merge commit 'perf/core' into perf/hw-breakpoint 2009-10-18 01:12:33 +02:00
tsc_sync.c x86: Reduce verbosity of "TSC is reliable" message 2009-09-24 11:35:19 +02:00
tsc.c Merge branch 'linus' into x86/urgent 2009-09-20 20:25:03 +02:00
uv_irq.c x86, apic: remove genapic.h 2009-02-17 17:52:44 +01:00
uv_sysfs.c x86: prevent /sys/firmware/sgi_uv from being created on non-uv systems 2009-04-08 14:58:10 +02:00
uv_time.c uv_time: add parameter to uv_read_rtc() 2009-04-22 17:41:25 +02:00
verify_cpu_64.S
visws_quirks.c x86: Add timer_init to x86_init_ops 2009-08-31 09:35:46 +02:00
vm86_32.c Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-06-10 16:15:14 -07:00
vmi_32.c x86, vmi: Mark VMI deprecated and schedule it for removal 2009-10-08 22:27:55 +02:00
vmiclock_32.c x86: Move tsc_calibration to x86_init_ops 2009-08-31 09:35:47 +02:00
vmlinux.lds.S x86: Document linker script ASSERT() quirk 2009-10-16 07:18:46 +02:00
vsmp_64.c Revert "x86: don't compile vsmp_64 for 32bit" 2009-03-25 21:34:28 +01:00
vsyscall_64.c sysctl: remove "struct file *" argument of ->proc_handler 2009-09-24 07:21:04 -07:00
x86_init.c x86: Move get/set_wallclock to x86_platform_ops 2009-09-16 14:34:50 +02:00
x8664_ksyms_64.c
xsave.c x86-64: fix FPU corruption with signals and preemption 2009-04-20 14:33:00 -07:00