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  1. 21 7月, 2011 5 次提交
  3. 16 7月, 2011 11 次提交
  5. 15 7月, 2011 5 次提交
    • S
      ftrace: Fix regression where ftrace breaks when modules are loaded · f7bc8b61
      由 Steven Rostedt 提交于 
      Enabling function tracer to trace all functions, then load a module and
then disable function tracing will cause ftrace to fail.

This can also happen by enabling function tracing on the command line:

  ftrace=function

and during boot up, modules are loaded, then you disable function tracing
with 'echo nop > current_tracer' you will trigger a bug in ftrace that
will shut itself down.

The reason is, the new ftrace code keeps ref counts of all ftrace_ops that
are registered for tracing. When one or more ftrace_ops are registered,
all the records that represent the functions that the ftrace_ops will
trace have a ref count incremented. If this ref count is not zero,
when the code modification runs, that function will be enabled for tracing.
If the ref count is zero, that function will be disabled from tracing.

To make sure the accounting was working, FTRACE_WARN_ON()s were added
to updating of the ref counts.

If the ref count hits its max (> 2^30 ftrace_ops added), or if
the ref count goes below zero, a FTRACE_WARN_ON() is triggered which
disables all modification of code.

Since it is common for ftrace_ops to trace all functions in the kernel,
instead of creating > 20,000 hash items for the ftrace_ops, the hash
count is just set to zero, and it represents that the ftrace_ops is
to trace all functions. This is where the issues arrise.

If you enable function tracing to trace all functions, and then add
a module, the modules function records do not get the ref count updated.
When the function tracer is disabled, all function records ref counts
are subtracted. Since the modules never had their ref counts incremented,
they go below zero and the FTRACE_WARN_ON() is triggered.

The solution to this is rather simple. When modules are loaded, and
their functions are added to the the ftrace pool, look to see if any
ftrace_ops are registered that trace all functions. And for those,
update the ref count for the module function records.
Reported-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      f7bc8b61
    • M
      tracing/kprobes: Rename probe_* to trace_probe_* · 7143f168
      由 Masami Hiramatsu 提交于 
      Rename probe_* to trace_probe_* for avoiding namespace
confliction. This also fixes improper names of find_probe_event()
and cleanup_all_probes() to find_trace_probe() and
release_all_trace_probes() respectively.
Signed-off-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20110627072636.6528.60374.stgit@fedora15Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      7143f168
    • C
      perf, x86: P4 PMU - Introduce event alias feature · f9129870
      由 Cyrill Gorcunov 提交于 
      Instead of hw_nmi_watchdog_set_attr() weak function
and appropriate x86_pmu::hw_watchdog_set_attr() call
we introduce even alias mechanism which allow us
to drop this routines completely and isolate quirks
of Netburst architecture inside P4 PMU code only.

The main idea remains the same though -- to allow
nmi-watchdog and perf top run simultaneously.

Note the aliasing mechanism applies to generic
PERF_COUNT_HW_CPU_CYCLES event only because arbitrary
event (say passed as RAW initially) might have some
additional bits set inside ESCR register changing
the behaviour of event and we can't guarantee anymore
that alias event will give the same result.

P.S. Thanks a huge to Don and Steven for for testing
     and early review.
Acked-by: NDon Zickus <dzickus@redhat.com>
Tested-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
CC: Ingo Molnar <mingo@elte.hu>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Stephane Eranian <eranian@google.com>
CC: Lin Ming <ming.m.lin@intel.com>
CC: Arnaldo Carvalho de Melo <acme@redhat.com>
CC: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20110708201712.GS23657@sunSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>
      f9129870
    • S
      tracing: Have dynamic size event stack traces · 4a9bd3f1
      由 Steven Rostedt 提交于 
      Currently the stack trace per event in ftace is only 8 frames.
This can be quite limiting and sometimes useless. Especially when
the "ignore frames" is wrong and we also use up stack frames for
the event processing itself.

Change this to be dynamic by adding a percpu buffer that we can
write a large stack frame into and then copy into the ring buffer.

For interrupts and NMIs that come in while another event is being
process, will only get to use the 8 frame stack. That should be enough
as the task that it interrupted will have the full stack frame anyway.
Requested-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      4a9bd3f1
    • S
      perf: Robustify proc and debugfs file recording · 259032bf
      由 Sonny Rao 提交于 
      While attempting to create a timechart of boot up I found perf didn't
tolerate modules being loaded/unloaded.  This patch fixes this by
reading the file once and then writing the size read at the correct
point in the file.  It also simplifies the code somewhat.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: NSonny Rao <sonnyrao@chromium.org>
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Link: http://lkml.kernel.org/r/10011.1310614483@neuling.orgSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>
      259032bf
  7. 14 7月, 2011 3 次提交
    • S
      ftrace: Fix dynamic selftest failure on some archs · 6331c28c
      由 Steven Rostedt 提交于 
      Archs that do not implement CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST, will
fail the dynamic ftrace selftest.

The function tracer has a quick 'off' variable that will prevent
the call back functions from being called. This variable is called
function_trace_stop. In x86, this is implemented directly in the mcount
assembly, but for other archs, an intermediate function is used called
ftrace_test_stop_func().

In dynamic ftrace, the function pointer variable ftrace_trace_function is
used to update the caller code in the mcount caller. But for archs that
do not have CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST set, it only calls
ftrace_test_stop_func() instead, which in turn calls __ftrace_trace_function.

When more than one ftrace_ops is registered, the function it calls is
ftrace_ops_list_func(), which will iterate over all registered ftrace_ops
and call the callbacks that have their hash matching.

The issue happens when two ftrace_ops are registered for different functions
and one is then unregistered. The __ftrace_trace_function is then pointed
to the remaining ftrace_ops callback function directly. This mean it will
be called for all functions that were registered to trace by both ftrace_ops
that were registered.

This is not an issue for archs with CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST,
because the update of ftrace_trace_function doesn't happen until after all
functions have been updated, and then the mcount caller is updated. But
for those archs that do use the ftrace_test_stop_func(), the update is
immediate.

The dynamic selftest fails because it hits this situation, and the
ftrace_ops that it registers fails to only trace what it was suppose to
and instead traces all other functions.

The solution is to delay the setting of __ftrace_trace_function until
after all the functions have been updated according to the registered
ftrace_ops. Also, function_trace_stop is set during the update to prevent
function tracing from calling code that is caused by the function tracer
itself.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      6331c28c
    • S
      ftrace: Update filter when tracing enabled in set_ftrace_filter() · 072126f4
      由 Steven Rostedt 提交于 
      Currently, if set_ftrace_filter() is called when the ftrace_ops is
active, the function filters will not be updated. They will only be updated
when tracing is disabled and re-enabled.

Update the functions immediately during set_ftrace_filter().
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      072126f4
    • S
      ftrace: Balance records when updating the hash · 41fb61c2
      由 Steven Rostedt 提交于 
      Whenever the hash of the ftrace_ops is updated, the record counts
must be balance. This requires disabling the records that are set
in the original hash, and then enabling the records that are set
in the updated hash.

Moving the update into ftrace_hash_move() removes the bug where the
hash was updated but the records were not, which results in ftrace
triggering a warning and disabling itself because the ftrace_ops filter
is updated while the ftrace_ops was registered, and then the failure
happens when the ftrace_ops is unregistered.

The current code will not trigger this bug, but new code will.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      41fb61c2
  9. 11 7月, 2011 1 次提交
  11. 08 7月, 2011 3 次提交
    • S
      ftrace: Do not disable interrupts for modules in mcount update · 4376cac6
      由 Steven Rostedt 提交于 
      When I mounted an NFS directory, it caused several modules to be loaded. At the
time I was running the preemptirqsoff tracer, and it showed the following
output:

# tracer: preemptirqsoff
#
# preemptirqsoff latency trace v1.1.5 on 2.6.33.9-rt30-mrg-test
# --------------------------------------------------------------------
# latency: 1177 us, #4/4, CPU#3 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:4)
#    -----------------
#    | task: modprobe-19370 (uid:0 nice:0 policy:0 rt_prio:0)
#    -----------------
#  => started at: ftrace_module_notify
#  => ended at:   ftrace_module_notify
#
#
#                  _------=> CPU#
#                 / _-----=> irqs-off
#                | / _----=> need-resched
#                || / _---=> hardirq/softirq
#                ||| / _--=> preempt-depth
#                |||| /_--=> lock-depth
#                |||||/     delay
#  cmd     pid   |||||| time  |   caller
#     \   /      ||||||   \   |   /
modprobe-19370   3d....    0us!: ftrace_process_locs <-ftrace_module_notify
modprobe-19370   3d.... 1176us : ftrace_process_locs <-ftrace_module_notify
modprobe-19370   3d.... 1178us : trace_hardirqs_on <-ftrace_module_notify
modprobe-19370   3d.... 1178us : <stack trace>
 => ftrace_process_locs
 => ftrace_module_notify
 => notifier_call_chain
 => __blocking_notifier_call_chain
 => blocking_notifier_call_chain
 => sys_init_module
 => system_call_fastpath

That's over 1ms that interrupts are disabled on a Real-Time kernel!

Looking at the cause (being the ftrace author helped), I found that the
interrupts are disabled before the code modification of mcounts into nops. The
interrupts only need to be disabled on start up around this code, not when
modules are being loaded.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      4376cac6
    • S
      tracing: Still trace filtered irq functions when irq trace is disabled · e4a3f541
      由 Steven Rostedt 提交于 
      If a function is set to be traced by the set_graph_function, but the
option funcgraph-irqs is zero, and the traced function happens to be
called from a interrupt, it will not be traced.

The point of funcgraph-irqs is to not trace interrupts when we are
preempted by an irq, not to not trace functions we want to trace that
happen to be *in* a irq.

Luckily the current->trace_recursion element is perfect to add a flag
to help us be able to trace functions within an interrupt even when
we are not tracing interrupts that preempt the trace.
Reported-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      e4a3f541
    • S
      tracing, x86/irq: Do not trace arch_local_{*,irq_*}() functions · e08fbb78
      由 Steven Rostedt 提交于 
      I triggered a triple fault with gcc 4.5.1 because it did not
honor the inline annotation to arch_local_save_flags() function
and that function was added to the pool of functions traced by
the function tracer.

When preempt_schedule() called arch_local_save_flags() (called
by irqs_disabled()), it was traced, but the first thing the
function tracer does is disable preemption. When it enables
preemption, the NEED_RESCHED flag will not have been cleared and
the preemption check will trigger the call to preempt_schedule()
again.

Although the dynamic function tracer crashed immediately, the
static version of the function tracer (CONFIG_DYNAMIC_FTRACE is
not set) actually was able to show where the problem was.

 swapper-1       3.N.. 103885us : arch_local_save_flags <-preempt_schedule
 swapper-1       3.N.. 103886us : arch_local_save_flags <-preempt_schedule
 swapper-1       3.N.. 103886us : arch_local_save_flags <-preempt_schedule
 swapper-1       3.N.. 103887us : arch_local_save_flags <-preempt_schedule
 swapper-1       3.N.. 103887us : arch_local_save_flags <-preempt_schedule
 swapper-1       3.N.. 103888us : arch_local_save_flags <-preempt_schedule
 swapper-1       3.N.. 103888us : arch_local_save_flags <-preempt_schedule

It went on for a while before it triple faulted with a corrupted
stack.

The arch_local_save_flags and arch_local_irq_* functions should
not be traced. Even though they are marked as inline, gcc may
still make them a function and enable tracing of them.

The simple solution is to just mark them as notrace. I had to
add the <linux/types.h> for this file to include the notrace
tag.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20110702033852.733414762@goodmis.orgSigned-off-by: NIngo Molnar <mingo@elte.hu>
      e08fbb78
  13. 07 7月, 2011 3 次提交
    • S
      ftrace: Fix regression of :mod:module function enabling · 43dd61c9
      由 Steven Rostedt 提交于 
      The new code that allows different utilities to pick and choose
what functions they trace broke the :mod: hook that allows users
to trace only functions of a particular module.

The reason is that the :mod: hook bypasses the hash that is setup
to allow individual users to trace their own functions and uses
the global hash directly. But if the global hash has not been
set up, it will cause a bug:

echo '*:mod:radeon' > /sys/kernel/debug/set_ftrace_filter

produces:

 [drm:drm_mode_getfb] *ERROR* invalid framebuffer id
 [drm:radeon_crtc_page_flip] *ERROR* failed to reserve new rbo buffer before flip
 BUG: unable to handle kernel paging request at ffffffff8160ec90
 IP: [<ffffffff810d9136>] add_hash_entry+0x66/0xd0
 PGD 1a05067 PUD 1a09063 PMD 80000000016001e1
 Oops: 0003 [#1] SMP Jul  7 04:02:28 phyllis kernel: [55303.858604] CPU 1
 Modules linked in: cryptd aes_x86_64 aes_generic binfmt_misc rfcomm bnep ip6table_filter hid radeon r8169 ahci libahci mii ttm drm_kms_helper drm video i2c_algo_bit intel_agp intel_gtt

 Pid: 10344, comm: bash Tainted: G        WC  3.0.0-rc5 #1 Dell Inc. Inspiron N5010/0YXXJJ
 RIP: 0010:[<ffffffff810d9136>]  [<ffffffff810d9136>] add_hash_entry+0x66/0xd0
 RSP: 0018:ffff88003a96bda8  EFLAGS: 00010246
 RAX: ffff8801301735c0 RBX: ffffffff8160ec80 RCX: 0000000000306ee0
 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880137c92940
 RBP: ffff88003a96bdb8 R08: ffff880137c95680 R09: 0000000000000000
 R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff81c9df78
 R13: ffff8801153d1000 R14: 0000000000000000 R15: 0000000000000000
 FS: 00007f329c18a700(0000) GS:ffff880137c80000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: ffffffff8160ec90 CR3: 000000003002b000 CR4: 00000000000006e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
 Process bash (pid: 10344, threadinfo ffff88003a96a000, task ffff88012fcfc470)
 Stack:
  0000000000000fd0 00000000000000fc ffff88003a96be38 ffffffff810d92f5
  ffff88011c4c4e00 ffff880000000000 000000000b69f4d0 ffffffff8160ec80
  ffff8800300e6f06 0000000081130295 0000000000000282 ffff8800300e6f00
 Call Trace:
  [<ffffffff810d92f5>] match_records+0x155/0x1b0
  [<ffffffff810d940c>] ftrace_mod_callback+0xbc/0x100
  [<ffffffff810dafdf>] ftrace_regex_write+0x16f/0x210
  [<ffffffff810db09f>] ftrace_filter_write+0xf/0x20
  [<ffffffff81166e48>] vfs_write+0xc8/0x190
  [<ffffffff81167001>] sys_write+0x51/0x90
  [<ffffffff815c7e02>] system_call_fastpath+0x16/0x1b
 Code: 48 8b 33 31 d2 48 85 f6 75 33 49 89 d4 4c 03 63 08 49 8b 14 24 48 85 d2 48 89 10 74 04 48 89 42 08 49 89 04 24 4c 89 60 08 31 d2
 RIP [<ffffffff810d9136>] add_hash_entry+0x66/0xd0
  RSP <ffff88003a96bda8>
 CR2: ffffffff8160ec90
 ---[ end trace a5d031828efdd88e ]---
Reported-by: NBrian Marete <marete@toshnix.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      43dd61c9
    • S
      tracing: Have "enable" file use refcounts like the "filter" file · 40ee4dff
      由 Steven Rostedt 提交于 
      The "enable" file for the event system can be removed when a module
is unloaded and the event system only has events from that module.
As the event system nr_events count goes to zero, it may be freed
if its ref_count is also set to zero.

Like the "filter" file, the "enable" file may be opened by a task and
referenced later, after a module has been unloaded and the events for
that event system have been removed.

Although the "filter" file referenced the event system structure,
the "enable" file only references a pointer to the event system
name. Since the name is freed when the event system is removed,
it is possible that an access to the "enable" file may reference
a freed pointer.

Update the "enable" file to use the subsystem_open() routine that
the "filter" file uses, to keep a reference to the event system
structure while the "enable" file is opened.

Cc: <stable@kernel.org>
Reported-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      40ee4dff
    • S
      tracing: Fix bug when reading system filters on module removal · e9dbfae5
      由 Steven Rostedt 提交于 
      The event system is freed when its nr_events is set to zero. This happens
when a module created an event system and then later the module is
removed. Modules may share systems, so the system is allocated when
it is created and freed when the modules are unloaded and all the
events under the system are removed (nr_events set to zero).

The problem arises when a task opened the "filter" file for the
system. If the module is unloaded and it removed the last event for
that system, the system structure is freed. If the task that opened
the filter file accesses the "filter" file after the system has
been freed, the system will access an invalid pointer.

By adding a ref_count, and using it to keep track of what
is using the event system, we can free it after all users
are finished with the event system.

Cc: <stable@kernel.org>
Reported-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      e9dbfae5
  15. 05 7月, 2011 2 次提交
  17. 04 7月, 2011 2 次提交
  19. 03 7月, 2011 5 次提交
    • F
      x86: Don't use frame pointer to save old stack on irq entry · a2bbe750
      由 Frederic Weisbecker 提交于 
      rbp is used in SAVE_ARGS_IRQ to save the old stack pointer
in order to restore it later in ret_from_intr.

It is convenient because we save its value in the irq regs
and it's easily restored using the leave instruction.

However this is a kind of abuse of the frame pointer which
role is to help unwinding the kernel by chaining frames
together, each node following the return address to the
previous frame.

But although we are breaking the frame by changing the stack
pointer, there is no preceding return address before the new
frame. Hence using the frame pointer to link the two stacks
breaks the stack unwinders that find a random value instead of
a return address here.

There is no workaround that can work in every case. We are using
the fixup_bp_irq_link() function to dereference that abused frame
pointer in the case of non nesting interrupt (which means stack
changed).
But that doesn't fix the case of interrupts that don't change the
stack (but we still have the unconditional frame link), which is
the case of hardirq interrupting softirq. We have no way to detect
this transition so the frame irq link is considered as a real frame
pointer and the return address is dereferenced but it is still a
spurious one.

There are two possible results of this: either the spurious return
address, a random stack value, luckily belongs to the kernel text
and then the unwinding can continue and we just have a weird entry
in the stack trace. Or it doesn't belong to the kernel text and
unwinding stops there.

This is the reason why stacktraces (including perf callchains) on
irqs that interrupted softirqs don't work very well.

To solve this, we don't save the old stack pointer on rbp anymore
but we save it to a scratch register that we push on the new
stack and that we pop back later on irq return.

This preserves the whole frame chain without spurious return addresses
in the middle and drops the need for the horrid fixup_bp_irq_link()
workaround.

And finally irqs that interrupt softirq are sanely unwinded.

Before:

    99.81%         perf  [kernel.kallsyms]  [k] perf_pending_event
                   |
                   --- perf_pending_event
                       irq_work_run
                       smp_irq_work_interrupt
                       irq_work_interrupt
                      |
                      |--41.60%-- __read
                      |          |
                      |          |--99.90%-- create_worker
                      |          |          bench_sched_messaging
                      |          |          cmd_bench
                      |          |          run_builtin
                      |          |          main
                      |          |          __libc_start_main
                      |           --0.10%-- [...]

After:

     1.64%  swapper  [kernel.kallsyms]  [k] perf_pending_event
            |
            --- perf_pending_event
                irq_work_run
                smp_irq_work_interrupt
                irq_work_interrupt
               |
               |--95.00%-- arch_irq_work_raise
               |          irq_work_queue
               |          __perf_event_overflow
               |          perf_swevent_overflow
               |          perf_swevent_event
               |          perf_tp_event
               |          perf_trace_softirq
               |          __do_softirq
               |          call_softirq
               |          do_softirq
               |          irq_exit
               |          |
               |          |--73.68%-- smp_apic_timer_interrupt
               |          |          apic_timer_interrupt
               |          |          |
               |          |          |--96.43%-- amd_e400_idle
               |          |          |          cpu_idle
               |          |          |          start_secondary
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jan Beulich <JBeulich@novell.com>
      a2bbe750
    • F
      x86: Remove useless unwinder backlink from irq regs saving · 48ffee7d
      由 Frederic Weisbecker 提交于 
      The unwinder backlink in interrupt entry is very useless.
It's actually not part of the stack frame chain and thus is
never used.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jan Beulich <JBeulich@novell.com>
      48ffee7d
    • F
      x86,64: Separate arg1 from rbp handling in SAVE_REGS_IRQ · 3b99a3ef
      由 Frederic Weisbecker 提交于 
      Just for clarity in the code. Have a first block that handles
the frame pointer and a separate one that handles pt_regs
pointer and its use.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jan Beulich <JBeulich@novell.com>
      3b99a3ef
    • F
      x86,64: Simplify save_regs() · 1871853f
      由 Frederic Weisbecker 提交于 
      The save_regs function that saves the regs on low level
irq entry is complicated because of the fact it changes
its stack in the middle and also because it manipulates
data allocated in the caller frame and accesses there
are directly calculated from callee rsp value with the
return address in the middle of the way.

This complicates the static stack offsets calculation and
require more dynamic ones. It also needs a save/restore
of the function's return address.

To simplify and optimize this, turn save_regs() into a
macro.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jan Beulich <JBeulich@novell.com>
      1871853f
    • F
      x86: Fetch stack from regs when possible in dump_trace() · 47ce11a2
      由 Frederic Weisbecker 提交于 
      When regs are passed to dump_stack(), we fetch the frame
pointer from the regs but the stack pointer is taken from
the current frame.

Thus the frame and stack pointers may not come from the same
context. For example this can result in the unwinder to
think the context is in irq, due to the current value of
the stack, but the frame pointer coming from the regs points
to a frame from another place. It then tries to fix up
the irq link but ends up dereferencing a random frame
pointer that doesn't belong to the irq stack:

[ 9131.706906] ------------[ cut here ]------------
[ 9131.707003] WARNING: at arch/x86/kernel/dumpstack_64.c:129 dump_trace+0x2aa/0x330()
[ 9131.707003] Hardware name: AMD690VM-FMH
[ 9131.707003] Perf: bad frame pointer = 0000000000000005 in callchain
[ 9131.707003] Modules linked in:
[ 9131.707003] Pid: 1050, comm: perf Not tainted 3.0.0-rc3+ #181
[ 9131.707003] Call Trace:
[ 9131.707003]  <IRQ>  [<ffffffff8104bd4a>] warn_slowpath_common+0x7a/0xb0
[ 9131.707003]  [<ffffffff8104be21>] warn_slowpath_fmt+0x41/0x50
[ 9131.707003]  [<ffffffff8178b873>] ? bad_to_user+0x6d/0x10be
[ 9131.707003]  [<ffffffff8100c2da>] dump_trace+0x2aa/0x330
[ 9131.707003]  [<ffffffff810107d3>] ? native_sched_clock+0x13/0x50
[ 9131.707003]  [<ffffffff8101b164>] perf_callchain_kernel+0x54/0x70
[ 9131.707003]  [<ffffffff810d391f>] perf_prepare_sample+0x19f/0x2a0
[ 9131.707003]  [<ffffffff810d546c>] __perf_event_overflow+0x16c/0x290
[ 9131.707003]  [<ffffffff810d5430>] ? __perf_event_overflow+0x130/0x290
[ 9131.707003]  [<ffffffff810107d3>] ? native_sched_clock+0x13/0x50
[ 9131.707003]  [<ffffffff8100fbb9>] ? sched_clock+0x9/0x10
[ 9131.707003]  [<ffffffff810752e5>] ? T.375+0x15/0x90
[ 9131.707003]  [<ffffffff81084da4>] ? trace_hardirqs_on_caller+0x64/0x180
[ 9131.707003]  [<ffffffff810817bd>] ? trace_hardirqs_off+0xd/0x10
[ 9131.707003]  [<ffffffff810d5764>] perf_event_overflow+0x14/0x20
[ 9131.707003]  [<ffffffff810d588c>] perf_swevent_hrtimer+0x11c/0x130
[ 9131.707003]  [<ffffffff817821a1>] ? error_exit+0x51/0xb0
[ 9131.707003]  [<ffffffff81072e93>] __run_hrtimer+0x83/0x1e0
[ 9131.707003]  [<ffffffff810d5770>] ? perf_event_overflow+0x20/0x20
[ 9131.707003]  [<ffffffff81073256>] hrtimer_interrupt+0x106/0x250
[ 9131.707003]  [<ffffffff812a3bfd>] ? trace_hardirqs_off_thunk+0x3a/0x3c
[ 9131.707003]  [<ffffffff81024833>] smp_apic_timer_interrupt+0x53/0x90
[ 9131.707003]  [<ffffffff81789053>] apic_timer_interrupt+0x13/0x20
[ 9131.707003]  <EOI>  [<ffffffff817821a1>] ? error_exit+0x51/0xb0
[ 9131.707003]  [<ffffffff8178219c>] ? error_exit+0x4c/0xb0
[ 9131.707003] ---[ end trace b2560d4876709347 ]---

Fix this by simply taking the stack pointer from regs->sp
when regs are provided.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
      47ce11a2