Custom fields set for each type by prepending field argument with type.
For file with multiple event types (e.g., trace and S/W) display of an
event type suppressed by setting output fields to "".

e.g.,
perf record -ga -e sched:sched_switch -e cpu-clock -c 10000000 -R -- sleep 1
perf script

openssl 11496 [000]  9711.807107: cpu-clock-msecs:
        ffffffff810c22dc arch_local_irq_restore ([kernel.kallsyms])
        ffffffff810c518c __alloc_pages_nodemask ([kernel.kallsyms])
        ffffffff810297b2 pte_alloc_one ([kernel.kallsyms])
        ffffffff810d8b98 __pte_alloc ([kernel.kallsyms])
        ffffffff810daf07 handle_mm_fault ([kernel.kallsyms])
        ffffffff8138763a do_page_fault ([kernel.kallsyms])
        ffffffff81384a65 page_fault ([kernel.kallsyms])
            7f6130507d70 asn1_check_tlen (/lib64/libcrypto.so.1.0.0c)
                       0  ()

         openssl 11496 [000]  9711.808042: sched_switch: prev_comm=openssl ...
     kworker/0:0     4 [000]  9711.808067: sched_switch: prev_comm=kworker/...
         swapper     0 [001]  9711.808090: sched_switch: prev_comm=kworker/...
            sshd 11451 [001]  9711.808185: sched_switch: prev_comm=sshd pre...
swapper     0 [001]  9711.816155: cpu-clock-msecs:
        ffffffff81023609 native_safe_halt ([kernel.kallsyms])
        ffffffff8100132a cpu_idle ([kernel.kallsyms])
        ffffffff8137cf9b start_secondary ([kernel.kallsyms])

openssl 11496 [000]  9711.817104: cpu-clock-msecs:
            7f61304ad723 AES_cbc_encrypt (/lib64/libcrypto.so.1.0.0c)
            7fff3402f950  ()
        12f0debc9a785634  ()

swapper     0 [001]  9711.826155: cpu-clock-msecs:
        ffffffff81023609 native_safe_halt ([kernel.kallsyms])
        ffffffff8100132a cpu_idle ([kernel.kallsyms])
        ffffffff8137cf9b start_secondary ([kernel.kallsyms])

To suppress trace events within the file and use default output for S/W events:
perf script -f trace:

or to suppress S/W events and do default display for trace events:
perf script -f sw:

Custom field selections:
perf script -f sw:comm,tid,time -f trace:time,trace

         openssl 11496  9711.797162:
         swapper     0  9711.807071:
         openssl 11496  9711.807107:
 9711.808042: prev_comm=openssl prev_pid=11496 prev_prio=120 prev_state=R ...
 9711.808067: prev_comm=kworker/0:0 prev_pid=4 prev_prio=120 prev_state=S ...
 9711.808090: prev_comm=kworker/0:0 prev_pid=0 prev_prio=120 prev_state=R ...
 9711.808185: prev_comm=sshd prev_pid=11451 prev_prio=120 prev_state=S ==>...
         swapper     0  9711.816155:
         openssl 11496  9711.817104:
         swapper     0  9711.826155:
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <1299734608-5223-7-git-send-email-daahern@cisco.com>
Signed-off-by: David Ahern <daahern@cisco.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Add option to dump symbols found in events.

e.g., perf script -f comm,pid,tid,time,trace,sym

swapper     0/0       537.037184: prev_comm=swapper prev_pid=0 prev_prio=120...
        ffffffff81030350 perf_trace_sched_switch ([kernel.kallsyms])
        ffffffff81382ac5 schedule ([kernel.kallsyms])
        ffffffff8100134a cpu_idle ([kernel.kallsyms])
        ffffffff81370b39 rest_init ([kernel.kallsyms])
        ffffffff81696c23 start_kernel ([kernel.kallsyms].init.text)
        ffffffff816962af x86_64_start_reservations ([kernel.kallsyms].init.text)
        ffffffff816963b9 x86_64_start_kernel ([kernel.kallsyms].init.text)

sshd  1675/1675    537.037309: prev_comm=sshd prev_pid=1675 prev_prio=120...
        ffffffff81030350 perf_trace_sched_switch ([kernel.kallsyms])
        ffffffff81382ac5 schedule ([kernel.kallsyms])
        ffffffff813837aa schedule_hrtimeout_range_clock ([kernel.kallsyms])
        ffffffff81383886 schedule_hrtimeout_range ([kernel.kallsyms])
        ffffffff8110c4f9 poll_schedule_timeout ([kernel.kallsyms])
        ffffffff8110cd20 do_select ([kernel.kallsyms])
        ffffffff8110ced8 core_sys_select ([kernel.kallsyms])
        ffffffff8110d00d sys_select ([kernel.kallsyms])
        ffffffff81002bc2 system_call ([kernel.kallsyms])
            7f1647e56e93 __GI_select (/lib64/libc-2.12.90.so)

netstat  1692/1692    537.038664: prev_comm=netstat prev_pid=1692 prev_prio=...
        ffffffff81030350 perf_trace_sched_switch ([kernel.kallsyms])
        ffffffff81382ac5 schedule ([kernel.kallsyms])
        ffffffff81002c3a sysret_careful ([kernel.kallsyms])
            7f7a6cd1b210 __GI___libc_read (/lib64/libc-2.12.90.so)
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <1299734608-5223-6-git-send-email-daahern@cisco.com>
Signed-off-by: David Ahern <daahern@cisco.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Allow a user to select which fields to print to stdout for event data.
Options include comm (command name), tid (thread id), pid (process id),
time (perf timestamp), cpu, event (for event name), and trace (for
trace data).

Default is set to maintain compatibility with current output; this
feature does alter output format slightly -- no '-' between command
and pid/tid.

Thanks to Frederic Weisbecker for detailed suggestions on this approach.

Examples (output compressed)

1. trace, default format

perf record -ga -e sched:sched_switch
perf script

swapper    0 [000] 537.037184: sched_switch: prev_comm=swapper prev_pid=0...
   sshd 1675 [000] 537.037309: sched_switch: prev_comm=sshd prev_pid=1675...
netstat 1692 [001] 537.038664: sched_switch: prev_comm=netstat prev_pid=1692...

2. trace, custom format

perf record -ga -e sched:sched_switch
perf script -f comm,pid,time,trace     <--- omitting cpu and event name

swapper    0 537.037184: prev_comm=swapper prev_pid=0 prev_prio=120 ...
   sshd 1675 537.037309: prev_comm=sshd prev_pid=1675 prev_prio=120 ...
netstat 1692 537.038664: prev_comm=netstat prev_pid=1692 prev_prio=120 ...
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <1299734608-5223-5-git-send-email-daahern@cisco.com>
Signed-off-by: David Ahern <daahern@cisco.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

This change does impact output: latency data is trace specific and is
now printed after the common data - comm, tid, cpu, time and event name.
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <1299734608-5223-4-git-send-email-daahern@cisco.com>
Signed-off-by: David Ahern <daahern@cisco.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Next patch moves printing of 'common' data into perf-script which
removes the need for these functions.
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <1299734608-5223-3-git-send-email-daahern@cisco.com>
Signed-off-by: David Ahern <daahern@cisco.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Prepare for handling of samples for any event type.
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <1299734608-5223-2-git-send-email-daahern@cisco.com>
Signed-off-by: David Ahern <daahern@cisco.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Now the --filter option is usable with perf stat too.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
LKML-Reference: <1300117230-8404-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

While going thru each of the sym_entry fields looking to reduce it to
the set of entries needed when in an active symbols list, 'skip' should
really be in symbol, as we set it when loading the symtab.

And the space used by the basic symbol allocation remains the same as
we had 5 bytes of padding.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

And the DSO__ORIG_ enum to SYMTAB__, to clarify that this is about from
where the symtab was obtained.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

We can get it from syme->map->dso->kernel (that should be renamed to
origin, but leave this for another patch).

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

We can get that counter index from perf_top->sym_evsel->idx instead.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Merge branch 'perf/core' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux-2.6 into perf/core

If the kernel command line declares a tracer "ftrace=sometracer" and
that tracer is either not defined or is enabled after irqsoff,
then the irqs off selftest will fail with the following error:

Testing tracer irqsoff:
------------[ cut here ]------------
WARNING: at /home/rostedt/work/autotest/nobackup/linux-test.git/kernel/trace/tra
ce.c:713 update_max_tr_single+0xfa/0x11b()
Hardware name:
Modules linked in:
Pid: 1, comm: swapper Not tainted 2.6.38-rc8-test #1
Call Trace:
 [<c0441d9d>] ? warn_slowpath_common+0x65/0x7a
 [<c049adb2>] ? update_max_tr_single+0xfa/0x11b
 [<c0441dc1>] ? warn_slowpath_null+0xf/0x13
 [<c049adb2>] ? update_max_tr_single+0xfa/0x11b
 [<c049e454>] ? stop_critical_timing+0x154/0x204
 [<c049b54b>] ? trace_selftest_startup_irqsoff+0x5b/0xc1
 [<c049b54b>] ? trace_selftest_startup_irqsoff+0x5b/0xc1
 [<c049b54b>] ? trace_selftest_startup_irqsoff+0x5b/0xc1
 [<c049e529>] ? time_hardirqs_on+0x25/0x28
 [<c0468bca>] ? trace_hardirqs_on_caller+0x18/0x12f
 [<c0468cec>] ? trace_hardirqs_on+0xb/0xd
 [<c049b54b>] ? trace_selftest_startup_irqsoff+0x5b/0xc1
 [<c049b6b8>] ? register_tracer+0xf8/0x1a3
 [<c14e93fe>] ? init_irqsoff_tracer+0xd/0x11
 [<c040115e>] ? do_one_initcall+0x71/0x121
 [<c14e93f1>] ? init_irqsoff_tracer+0x0/0x11
 [<c14ce3a9>] ? kernel_init+0x13a/0x1b6
 [<c14ce26f>] ? kernel_init+0x0/0x1b6
 [<c0403842>] ? kernel_thread_helper+0x6/0x10
---[ end trace e93713a9d40cd06c ]---
.. no entries found ..FAILED!

What happens is the "ftrace=..." will expand the ring buffer to its
default size (from its minimum size) but it will not expand the
max ring buffer (the ring buffer to store maximum latencies).
When the irqsoff test runs, it will call the ring buffer swap routine
that checks if the max ring buffer is the same size as the normal
ring buffer, and will fail if it is not. This causes the test to fail.

The solution is to expand the max ring buffer before running the self
test if the max ring buffer is used by that tracer and the normal ring
buffer is expanded. The max ring buffer should be shrunk again after
the test is done to save space.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Move elements in struct tracer for better alignment.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Trace events belonging to a module only exists when the module is
loaded. Well, we can use trace_set_clr_event funtion to enable some
trace event at the module init routine, so that we will not miss
something while loading then module.

So, Export the trace_set_clr_event function so that module can use it.
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
LKML-Reference: <1289196312-25323-1-git-send-email-yuanhan.liu@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

The "Delta way too big" warning might appear on a system with a
unstable shed clock right after the system is resumed and tracing
was enabled at time of suspend.

Since it's not realy a bug, and the unstable sched clock is working
fast and reliable otherwise, Steven suggested to keep using the
sched clock in any case and just to make note in the warning itself.

v2 changes:
- added #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
LKML-Reference: <20110218145219.GD2604@jolsa.brq.redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Currently the index to the ret_stack is updated and the real return address
is saved in the ret_stack. Then we call the trace function. The trace
function could decide that it doesn't want to trace this function
(ex. set_graph_function does not match) and it will return 0 which means
not to trace this call.

The normal function graph tracer has this code:

	if (!(trace->depth || ftrace_graph_addr(trace->func)) ||
	      ftrace_graph_ignore_irqs())
		return 0;

What this states is, if the trace depth (which is curr_ret_stack)
is zero (top of nested functions) then test if we want to trace this
function. If this function is not to be traced, then return  0 and
the rest of the function graph tracer logic will not trace this function.

The problem arises when an interrupt comes in after we updated the
curr_ret_stack. The next function that gets called will have a trace->depth
of 1. Which fools this trace code into thinking that we are in a nested
function, and that we should trace. This causes interrupts to be traced
when they should not be.

The solution is to trace the function first and then update the ret_stack.
Reported-by: zhiping zhong <xzhong86@163.com>
Reported-by: wu zhangjin <wuzhangjin@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

The section .ref.text will not go away unexpectedly and is
safe to trace. Add it to the safe list of sections to allow
tracing.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Formatting change only to improve code readability. No code changes except to
introduce intermediate variables.
Signed-off-by: David Sharp <dhsharp@google.com>
LKML-Reference: <1291421609-14665-13-git-send-email-dhsharp@google.com>

[ Keep variable declarations and assignment separate ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David Sharp <dhsharp@google.com>
LKML-Reference: <1291421609-14665-10-git-send-email-dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Signed-off-by: David Sharp <dhsharp@google.com>
LKML-Reference: <1291421609-14665-9-git-send-email-dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Acked-by: Avi Kivity <avi@redhat.com>
Signed-off-by: David Sharp <dhsharp@google.com>
LKML-Reference: <1291421609-14665-8-git-send-email-dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: David Sharp <dhsharp@google.com>
LKML-Reference: <1291421609-14665-7-git-send-email-dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Signed-off-by: David Sharp <dhsharp@google.com>
LKML-Reference: <1291421609-14665-6-git-send-email-dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

The lock_depth field in the event headers was added as a temporary
data point for help in removing the BKL. Now that the BKL is pretty
much been removed, we can remove this field.

This in turn changes the header from 12 bytes to 8 bytes,
removing the 4 byte buffer that gcc would insert if the first field
in the data load was 8 bytes in size.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Stop using this python/OOP convention, doesn't really helps. Will do
more from time to time till we get it cleaned up in all of tools/perf.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <new-submission>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

So that we can reuse things like the id to attr lookup routine
(perf_evlist__id2evsel) that uses a hash table instead of the linear
lookup done in the older perf_header_attr routines, etc.

Also to make evsels/evlist more pervasive an API, simplyfing using the
emerging perf lib.

cc: Arun Sharma <arun@sharma-home.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Passing multiple events might force out information about pid/tid/cpu.
Attached patch leaves 30 characters for this info at the expense of the
events' names.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Han Pingtian <phan@redhat.com>
LKML-Reference: <1299528821-17521-3-git-send-email-jolsa@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

The snprintf function returns number of printed characters even if it
cross the size parameter. So passing enough events via '-e' parameter
will cause segmentation fault.

It's reproduced by following command:

perf top -e `perf list | grep Tracepoint | awk -F'[' '\
{gsub(/[[:space:]]+/,"",$1);array[FNR]=$1}END{outputs=array[1];\
for (i=2;i<=FNR;i++){ outputs=outputs "," array[i];};print outputs}'`

Attached patch is adding SNPRINTF macro that provides the overflow check
and returns actuall number of printed characters.
Reported-by: Han Pingtian <phan@redhat.com>
Cc: Han Pingtian <phan@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1299528821-17521-2-git-send-email-jolsa@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Signed-off-by: David Sharp <dhsharp@google.com>
LKML-Reference: <1291421609-14665-3-git-send-email-dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Add an "overwrite" trace_option for ftrace to control whether the buffer should
be overwritten on overflow or not. The default remains to overwrite old events
when the buffer is full. This patch adds the option to instead discard newest
events when the buffer is full. This is useful to get a snapshot of traces just
after enabling traces. Dropping the current event is also a simpler code path.
Signed-off-by: David Sharp <dhsharp@google.com>
LKML-Reference: <1291844807-15481-1-git-send-email-dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

You can crash the kernel (with root/admin privileges) using kprobe tracer by running:

 echo "p system_call_after_swapgs" > ./kprobe_events
 echo 1 > ./events/kprobes/enable

The reason is that at the system_call_after_swapgs label, the
kernel stack is not set up. If optimized kprobes are enabled,
the user space stack is being used in this case (see optimized
kprobe template) and this might result in a crash.

There are several places like this over the entry code
(entry_$BIT). As it seems there's no any reasonable/maintainable
way to disable only those places where the stack is not ready, I
switched off the whole entry code from kprobe optimizing.
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: acme@redhat.com
Cc: fweisbec@gmail.com
Cc: ananth@in.ibm.com
Cc: davem@davemloft.net
Cc: a.p.zijlstra@chello.nl
Cc: eric.dumazet@gmail.com
Cc: 2nddept-manager@sdl.hitachi.co.jp
LKML-Reference: <1298298313-5980-3-git-send-email-jolsa@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Put x86 entry code into a separate link section: .entry.text.

Separating the entry text section seems to have performance
benefits - caused by more efficient instruction cache usage.

Running hackbench with perf stat --repeat showed that the change
compresses the icache footprint. The icache load miss rate went
down by about 15%:

 before patch:
         19417627  L1-icache-load-misses      ( +-   0.147% )

 after patch:
         16490788  L1-icache-load-misses      ( +-   0.180% )

The motivation of the patch was to fix a particular kprobes
bug that relates to the entry text section, the performance
advantage was discovered accidentally.

Whole perf output follows:

 - results for current tip tree:

  Performance counter stats for './hackbench/hackbench 10' (500 runs):

         19417627  L1-icache-load-misses      ( +-   0.147% )
       2676914223  instructions             #      0.497 IPC     ( +- 0.079% )
       5389516026  cycles                     ( +-   0.144% )

      0.206267711  seconds time elapsed   ( +-   0.138% )

 - results for current tip tree with the patch applied:

  Performance counter stats for './hackbench/hackbench 10' (500 runs):

         16490788  L1-icache-load-misses      ( +-   0.180% )
       2717734941  instructions             #      0.502 IPC     ( +- 0.079% )
       5414756975  cycles                     ( +-   0.148% )

      0.206747566  seconds time elapsed   ( +-   0.137% )
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: masami.hiramatsu.pt@hitachi.com
Cc: ananth@in.ibm.com
Cc: davem@davemloft.net
Cc: 2nddept-manager@sdl.hitachi.co.jp
LKML-Reference: <20110307181039.GB15197@jolsa.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Merge reason: Merge latest fixes.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Merge branch 's5p-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/kgene/linux-samsung

* 's5p-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/kgene/linux-samsung:
  ARM: S3C64XX: Update regulator names for debugfs compatiblity on SMDK6410
  ARM: S3C64XX: Fix build with WM1190 disabled and WM1192 enabled on SMDK6410
  ARM: S3C64XX: Reduce output of s3c64xx_dma_init1()
  ARM: S3C64XX: Tone down SDHCI debugging
  ARM: S3C64XX: Add clock for i2c1
  ARM: S3C64XX: Staticise non-exported GPIO to interrupt functions
  ARM: SAMSUNG: Include devs.h in dev-uart.c to prototype devices
  ARM: S3C64XX: Fix keypad setup to configure correct number of rows
  ARM: S3C2440: Fix usage gpio bank j pin definitions on GTA02
  ARM: S5P64X0: Fix number of GPIO lines in Bank F
  ARM: S3C2440: Select missing S3C_DEV_USB_HOST on GTA02

* 'fixes' of master.kernel.org:/home/rmk/linux-2.6-arm:
  davinci: cpufreq: fix section mismatch warning
  DaVinci: fix compilation warnings in <mach/clkdev.h>
  davinci: tnetv107x: fix register indexing for GPIOs numbers > 31
  davinci: da8xx/omap-l1x: add platform device for davinci-pcm-audio
  ARM: pxa/tosa: register wm9712 codec device
  ARM: pxa: enable pxa-pcm-audio on pxa210/pxa25x platform
  ARM: pxa/colibri: don't register pxa2xx-pcmcia nodes on non-colibri platforms
  ARM: pxa/tosa: drop setting LED trigger name, as it's unsupported now
  ARM: 6762/1: Update number of VIC for S5P6442 and S5PC100
  ARM: 6761/1: Update number of VIC for S5PV210
  ARM: 6768/1: hw_breakpoint: ensure debug logic is powered up on v7 cores
  ARM: 6767/1: ptrace: fix register indexing in GETHBPREGS request
  ARM: 6765/1: remove obsolete comment from asm/mach/arch.h
  ARM: 6757/1: fix tlb.h induced linux/swap.h build failure

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/cjb/mmc:
  mmc: sdio: Allow sdio operations in other threads during sdio_add_func()

* 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6:
  drm: index i shadowed in 2nd loop
  drm/nv50-nvc0: prevent multiple vm/bar flushes occuring simultanenously
  drm/nouveau: fix regression causing ttm to not be able to evict vram
  drm/i915: Rebind the buffer if its alignment constraints changes with tiling
  drm/i915: Disable GPU semaphores by default
  drm/i915: Do not overflow the MMADDR write FIFO
  Revert "drm/i915: fix corruptions on i8xx due to relaxed fencing"

Index i was already used in thhe first loop
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>