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  1. 09 12月, 2009 1 次提交
    • F
      hw-breakpoints: Modify breakpoints without unregistering them · 44234adc
      由 Frederic Weisbecker 提交于 
      Currently, when ptrace needs to modify a breakpoint, like disabling
it, changing its address, type or len, it calls
modify_user_hw_breakpoint(). This latter will perform the heavy and
racy task of unregistering the old breakpoint and registering a new
one.

This is racy as someone else might steal the reserved breakpoint
slot under us, which is undesired as the breakpoint is only
supposed to be modified, sometimes in the middle of a debugging
workflow. We don't want our slot to be stolen in the middle.

So instead of unregistering/registering the breakpoint, just
disable it while we modify its breakpoint fields and re-enable it
after if necessary.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
LKML-Reference: <1260347148-5519-1-git-send-regression-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      44234adc
  3. 06 12月, 2009 5 次提交
    • F
      x86: Fixup wrong irq frame link in stacktraces · af2d8289
      由 Frederic Weisbecker 提交于 
      When we enter in irq, two things can happen to preserve the link
to the previous frame pointer:

- If we were in an irq already, we don't switch to the irq stack
  as we are inside. We just need to save the previous frame
  pointer and to link the new one to the previous.

- Otherwise we need another level of indirection. We enter the irq with
  the previous stack. We save the previous bp inside and make bp
  pointing to its saved address. Then we switch to the irq stack and
  push bp another time but to the new stack. This makes two levels to
  dereference instead of one.

In the second case, the current stacktrace code omits the second level
and loses the frame pointer accuracy. The stack that follows will then
be considered as unreliable.

Handling that makes the perf callchain happier.
Before:

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%-- 0x7f630878ce8

After:

    50.00%  [k] _raw_read_lock
            |
            --- _read_lock
               |
               |--98.97%-- send_sigio
               |          __kill_fasync
               |          kill_fasync
               |          evdev_pass_event
               |          evdev_event
               |          input_pass_event
               |          input_handle_event
               |          input_event
               |          |
               |          |--96.88%-- 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
               |          |          |
               |          |          |--39.78%-- __const_udelay
               |          |          |          |
               |          |          |          |--91.89%-- ath5k_hw_register_timeout
               |          |          |          |          ath5k_hw_noise_floor_calibration
               |          |          |          |          ath5k_hw_reset
               |          |          |          |          ath5k_reset
               |          |          |          |          ath5k_config
               |          |          |          |          ieee80211_hw_config
               |          |          |          |          |
               |          |          |          |          |--88.24%-- ieee80211_scan_work
               |          |          |          |          |          worker_thread
               |          |          |          |          |          kthread
               |          |          |          |          |          child_rip
               |          |          |          |          |
               |          |          |          |           --11.76%-- ieee80211_scan_completed
               |          |          |          |                     ieee80211_scan_work
               |          |          |          |                     worker_thread
               |          |          |          |                     kthread
               |          |          |          |                     child_rip
               |          |          |          |
               |          |          |           --8.11%-- ath5k_hw_noise_floor_calibration
               |          |          |                     ath5k_hw_reset
               |          |          |                     ath5k_reset
               |          |          |                     ath5k_config

Note: This does not only affect perf events but also x86-64
stacktraces. They were considered as unreliable once we quit
the irq stack frame.
Signed-off-by: NFrederic 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>
      af2d8289
    • F
      x86: Fixup wrong debug exception frame link in stacktraces · b625b3b3
      由 Frederic Weisbecker 提交于 
      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: NFrederic 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>
      b625b3b3
    • F
      x86/perf: Exclude the debug stack from the callchains · 7f33f9c5
      由 Frederic Weisbecker 提交于 
      Dumping the callchains from breakpoint events with perf gives strange
results:

3.75%             perf  [kernel]           [k] _raw_read_unlock
                       |
                       --- _raw_read_unlock
                           perf_callchain
                           perf_prepare_sample
                           __perf_event_overflow
                           perf_swevent_overflow
                           perf_swevent_add
                           perf_bp_event
                           hw_breakpoint_exceptions_notify
                           notifier_call_chain
                           __atomic_notifier_call_chain
                           atomic_notifier_call_chain
                           notify_die
                           do_debug
                           debug
                           munmap

We are infected with all the debug stack. Like the nmi stack, the debug
stack is undesired as it is part of the profiling path, not helpful for
the user.

Ignore it.
Signed-off-by: NFrederic 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>
      7f33f9c5
    • F
      hw-breakpoints: Use overflow handler instead of the event callback · b326e956
      由 Frederic Weisbecker 提交于 
      struct perf_event::event callback was called when a breakpoint
triggers. But this is a rather opaque callback, pretty
tied-only to the breakpoint API and not really integrated into perf
as it triggers even when we don't overflow.

We prefer to use overflow_handler() as it fits into the perf events
rules, being called only when we overflow.
Reported-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: "K. Prasad" <prasad@linux.vnet.ibm.com>
      b326e956
    • F
      hw-breakpoints: Drop callback and task parameters from modify helper · 2f0993e0
      由 Frederic Weisbecker 提交于 
      Drop the callback and task parameters from modify_user_hw_breakpoint().
For now we have no user that need to modify a breakpoint to the point
of changing its handler or its task context.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: "K. Prasad" <prasad@linux.vnet.ibm.com>
      2f0993e0
  5. 02 12月, 2009 1 次提交
  7. 27 11月, 2009 1 次提交
  9. 26 11月, 2009 3 次提交
  11. 25 11月, 2009 2 次提交
    • T
      x86: Rename global percpu symbol dr7 to cpu_dr7 · 28b4e0d8
      由 Tejun Heo 提交于 
      Percpu symbols now occupy the same namespace as other global
symbols and as such short global symbols without subsystem
prefix tend to collide with local variables.  dr7 percpu
variable used by x86 was hit by this. Rename it to cpu_dr7.

The rename also makes it more consistent with its fellow
cpu_debugreg percpu variable.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <20091125115856.GA17856@elte.hu>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
      28b4e0d8
    • S
      perf_events, x86: Fix validate_event bug · 1261a02a
      由 Stephane Eranian 提交于 
      The validate_event() was failing on valid event combinations. The
function was assuming that if x86_schedule_event() returned 0, it
meant error. But x86_schedule_event() returns the counter index and
0 is a perfectly valid value. An error is returned if the function
returns a negative value.

Furthermore, validate_event() was also failing for event groups
because the event->pmu was not set until after
hw_perf_event_init().
Signed-off-by: NStephane Eranian <eranian@google.com>
Cc: peterz@infradead.org
Cc: paulus@samba.org
Cc: perfmon2-devel@lists.sourceforge.net
Cc: eranian@gmail.com
LKML-Reference: <4b0bdf36.1818d00a.07cc.25ae@mx.google.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
--
 arch/x86/kernel/cpu/perf_event.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
      1261a02a
  13. 24 11月, 2009 2 次提交
  15. 23 11月, 2009 1 次提交
  17. 14 11月, 2009 1 次提交
    • I
      hw-breakpoints, x86: Fix modular KVM build · 68efa37d
      由 Ingo Molnar 提交于 
      This build error:

arch/x86/kvm/x86.c:3655: error: implicit declaration of function 'hw_breakpoint_restore'

Happens because in the CONFIG_KVM=m case there's no 'CONFIG_KVM' define
in the kernel - it's CONFIG_KVM_MODULE in that case.

Make the prototype available unconditionally.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
LKML-Reference: <1258114575-32655-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      68efa37d
  19. 12 11月, 2009 2 次提交
  21. 11 11月, 2009 1 次提交
  23. 10 11月, 2009 3 次提交
  25. 08 11月, 2009 2 次提交
    • J
      x86/PCI: Adjust GFP mask handling for coherent allocations · eb647138
      由 Jan Beulich 提交于 
      Rather than forcing GFP flags and DMA mask to be inconsistent,
GFP flags should be determined even for the fallback device
through dma_alloc_coherent_mask()/dma_alloc_coherent_gfp_flags().

This restores 64-bit behavior as it was prior to commits
8965eb19 and
4a367f3a (not sure why there are
two of them), where GFP_DMA was forced on for 32-bit, but not
for 64-bit, with the slight adjustment that afaict even 32-bit
doesn't need this without CONFIG_ISA.
Signed-off-by: NJan Beulich <jbeulich@novell.com>
Acked-by: NTakashi Iwai <tiwai@suse.de>
LKML-Reference: <4AF18187020000780001D8AA@vpn.id2.novell.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
      eb647138
    • F
      hw-breakpoints: Rewrite the hw-breakpoints layer on top of perf events · 24f1e32c
      由 Frederic Weisbecker 提交于 
      This patch rebase the implementation of the breakpoints API on top of
perf events instances.

Each breakpoints are now perf events that handle the
register scheduling, thread/cpu attachment, etc..

The new layering is now made as follows:

       ptrace       kgdb      ftrace   perf syscall
          \          |          /         /
           \         |         /         /
                                        /
            Core breakpoint API        /
                                      /
                     |               /
                     |              /

              Breakpoints perf events

                     |
                     |

               Breakpoints PMU ---- Debug Register constraints handling
                                    (Part of core breakpoint API)
                     |
                     |

             Hardware debug registers

Reasons of this rewrite:

- Use the centralized/optimized pmu registers scheduling,
  implying an easier arch integration
- More powerful register handling: perf attributes (pinned/flexible
  events, exclusive/non-exclusive, tunable period, etc...)

Impact:

- New perf ABI: the hardware breakpoints counters
- Ptrace breakpoints setting remains tricky and still needs some per
  thread breakpoints references.

Todo (in the order):

- Support breakpoints perf counter events for perf tools (ie: implement
  perf_bpcounter_event())
- Support from perf tools

Changes in v2:

- Follow the perf "event " rename
- The ptrace regression have been fixed (ptrace breakpoint perf events
  weren't released when a task ended)
- Drop the struct hw_breakpoint and store generic fields in
  perf_event_attr.
- Separate core and arch specific headers, drop
  asm-generic/hw_breakpoint.h and create linux/hw_breakpoint.h
- Use new generic len/type for breakpoint
- Handle off case: when breakpoints api is not supported by an arch

Changes in v3:

- Fix broken CONFIG_KVM, we need to propagate the breakpoint api
  changes to kvm when we exit the guest and restore the bp registers
  to the host.

Changes in v4:

- Drop the hw_breakpoint_restore() stub as it is only used by KVM
- EXPORT_SYMBOL_GPL hw_breakpoint_restore() as KVM can be built as a
  module
- Restore the breakpoints unconditionally on kvm guest exit:
  TIF_DEBUG_THREAD doesn't anymore cover every cases of running
  breakpoints and vcpu->arch.switch_db_regs might not always be
  set when the guest used debug registers.
  (Waiting for a reliable optimization)

Changes in v5:

- Split-up the asm-generic/hw-breakpoint.h moving to
  linux/hw_breakpoint.h into a separate patch
- Optimize the breakpoints restoring while switching from kvm guest
  to host. We only want to restore the state if we have active
  breakpoints to the host, otherwise we don't care about messed-up
  address registers.
- Add asm/hw_breakpoint.h to Kbuild
- Fix bad breakpoint type in trace_selftest.c

Changes in v6:

- Fix wrong header inclusion in trace.h (triggered a build
  error with CONFIG_FTRACE_SELFTEST
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jan Kiszka <jan.kiszka@web.de>
Cc: Jiri Slaby <jirislaby@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Paul Mundt <lethal@linux-sh.org>
      24f1e32c
  27. 07 11月, 2009 1 次提交
  29. 04 11月, 2009 2 次提交
    • S
      x86, fs: Fix x86 procfs stack information for threads on 64-bit · 89240ba0
      由 Stefani Seibold 提交于 
      This patch fixes two issues in the procfs stack information on
x86-64 linux.

The 32 bit loader compat_do_execve did not store stack
start. (this was figured out by Alexey Dobriyan).

The stack information on a x64_64 kernel always shows 0 kbyte
stack usage, because of a missing implementation of the KSTK_ESP
macro which always returned -1.

The new implementation now returns the right value.
Signed-off-by: NStefani Seibold <stefani@seibold.net>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <1257240160.4889.24.camel@wall-e>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      89240ba0
    • P
      x86/hw-breakpoints: Actually flush thread breakpoints in flush_thread(). · 41a48d14
      由 Paul Mundt 提交于 
      flush_thread() tries to do a TIF_DEBUG check before calling in to
flush_thread_hw_breakpoint() (which subsequently clears the thread flag),
but for some reason, the x86 code is manually clearing TIF_DEBUG
immediately before the test, so this path will never be taken.

This kills off the erroneous clear_tsk_thread_flag() and lets
flush_thread_hw_breakpoint() actually get invoked.

Presumably folks were getting lucky with testing and the
free_thread_info() -> free_thread_xstate() path was taking care of the
flush there.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>
Acked-by: N"K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alan Stern <stern@rowland.harvard.edu>
LKML-Reference: <20091005102306.GA7889@linux-sh.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
      41a48d14
  31. 02 11月, 2009 2 次提交
  33. 29 10月, 2009 1 次提交
  35. 27 10月, 2009 1 次提交
  37. 26 10月, 2009 1 次提交
    • J
      x86: crash_dump: Fix non-pae kdump kernel memory accesses · 72ed7de7
      由 Jiri Slaby 提交于 
      Non-PAE 32-bit dump kernels may wrap an address around 4G and
poke unwanted space. ptes there are 32-bit long, and since
pfn << PAGE_SIZE may exceed this limit, high pfn bits are
cropped and wrong address mapped by kmap_atomic_pfn in
copy_oldmem_page.

Don't allow this behavior in non-PAE kdump kernels by checking
pfns passed into copy_oldmem_page. In the case of failure,
userspace process gets EFAULT.

[v2]
- fix comments
- move ifdefs inside the function
Signed-off-by: NJiri Slaby <jirislaby@gmail.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Simon Horman <horms@verge.net.au>
Cc: Paul Mundt <lethal@linux-sh.org>
LKML-Reference: <1256551903-30567-1-git-send-email-jirislaby@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      72ed7de7
  39. 16 10月, 2009 6 次提交
  41. 15 10月, 2009 1 次提交