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authorLinus Torvalds <torvalds@linux-foundation.org>2010-02-28 10:20:25 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2010-02-28 10:20:25 -0800
commit6556a6743549defc32e5f90ee2cb1ecd833a44c3 (patch)
tree622306583d4a3c13235a8bfc012854c125c597f1 /Documentation/trace
parente0d272429a34ff143bfa04ee8e29dd4eed2964c7 (diff)
parent1dd2980d990068e20045b90c424518cc7f3657ff (diff)
downloadlinux-linaro-stable-6556a6743549defc32e5f90ee2cb1ecd833a44c3.tar.gz
Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (172 commits) perf_event, amd: Fix spinlock initialization perf_event: Fix preempt warning in perf_clock() perf tools: Flush maps on COMM events perf_events, x86: Split PMU definitions into separate files perf annotate: Handle samples not at objdump output addr boundaries perf_events, x86: Remove superflous MSR writes perf_events: Simplify code by removing cpu argument to hw_perf_group_sched_in() perf_events, x86: AMD event scheduling perf_events: Add new start/stop PMU callbacks perf_events: Report the MMAP pgoff value in bytes perf annotate: Defer allocating sym_priv->hist array perf symbols: Improve debugging information about symtab origins perf top: Use a macro instead of a constant variable perf symbols: Check the right return variable perf/scripts: Tag syscall_name helper as not yet available perf/scripts: Add perf-trace-python Documentation perf/scripts: Remove unnecessary PyTuple resizes perf/scripts: Add syscall tracing scripts perf/scripts: Add Python scripting engine perf/scripts: Remove check-perf-trace from listed scripts ... Fix trivial conflict in tools/perf/util/probe-event.c
Diffstat (limited to 'Documentation/trace')
-rw-r--r--Documentation/trace/kprobetrace.txt57
1 files changed, 32 insertions, 25 deletions
diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index 47aabeebbdf6..a9100b28eb84 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -24,6 +24,7 @@ Synopsis of kprobe_events
-------------------------
p[:[GRP/]EVENT] SYMBOL[+offs]|MEMADDR [FETCHARGS] : Set a probe
r[:[GRP/]EVENT] SYMBOL[+0] [FETCHARGS] : Set a return probe
+ -:[GRP/]EVENT : Clear a probe
GRP : Group name. If omitted, use "kprobes" for it.
EVENT : Event name. If omitted, the event name is generated
@@ -37,15 +38,12 @@ Synopsis of kprobe_events
@SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symbol)
$stackN : Fetch Nth entry of stack (N >= 0)
$stack : Fetch stack address.
- $argN : Fetch function argument. (N >= 0)(*)
- $retval : Fetch return value.(**)
- +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***)
+ $retval : Fetch return value.(*)
+ +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**)
NAME=FETCHARG: Set NAME as the argument name of FETCHARG.
- (*) aN may not correct on asmlinkaged functions and at the middle of
- function body.
- (**) only for return probe.
- (***) this is useful for fetching a field of data structures.
+ (*) only for return probe.
+ (**) this is useful for fetching a field of data structures.
Per-Probe Event Filtering
@@ -82,13 +80,16 @@ Usage examples
To add a probe as a new event, write a new definition to kprobe_events
as below.
- echo p:myprobe do_sys_open dfd=$arg0 filename=$arg1 flags=$arg2 mode=$arg3 > /sys/kernel/debug/tracing/kprobe_events
+ echo 'p:myprobe do_sys_open dfd=%ax filename=%dx flags=%cx mode=+4($stack)' > /sys/kernel/debug/tracing/kprobe_events
This sets a kprobe on the top of do_sys_open() function with recording
-1st to 4th arguments as "myprobe" event. As this example shows, users can
-choose more familiar names for each arguments.
+1st to 4th arguments as "myprobe" event. Note, which register/stack entry is
+assigned to each function argument depends on arch-specific ABI. If you unsure
+the ABI, please try to use probe subcommand of perf-tools (you can find it
+under tools/perf/).
+As this example shows, users can choose more familiar names for each arguments.
- echo r:myretprobe do_sys_open $retval >> /sys/kernel/debug/tracing/kprobe_events
+ echo 'r:myretprobe do_sys_open $retval' >> /sys/kernel/debug/tracing/kprobe_events
This sets a kretprobe on the return point of do_sys_open() function with
recording return value as "myretprobe" event.
@@ -97,23 +98,24 @@ recording return value as "myretprobe" event.
cat /sys/kernel/debug/tracing/events/kprobes/myprobe/format
name: myprobe
-ID: 75
+ID: 780
format:
- field:unsigned short common_type; offset:0; size:2;
- field:unsigned char common_flags; offset:2; size:1;
- field:unsigned char common_preempt_count; offset:3; size:1;
- field:int common_pid; offset:4; size:4;
- field:int common_tgid; offset:8; size:4;
+ field:unsigned short common_type; offset:0; size:2; signed:0;
+ field:unsigned char common_flags; offset:2; size:1; signed:0;
+ field:unsigned char common_preempt_count; offset:3; size:1;signed:0;
+ field:int common_pid; offset:4; size:4; signed:1;
+ field:int common_lock_depth; offset:8; size:4; signed:1;
- field: unsigned long ip; offset:16;tsize:8;
- field: int nargs; offset:24;tsize:4;
- field: unsigned long dfd; offset:32;tsize:8;
- field: unsigned long filename; offset:40;tsize:8;
- field: unsigned long flags; offset:48;tsize:8;
- field: unsigned long mode; offset:56;tsize:8;
+ field:unsigned long __probe_ip; offset:12; size:4; signed:0;
+ field:int __probe_nargs; offset:16; size:4; signed:1;
+ field:unsigned long dfd; offset:20; size:4; signed:0;
+ field:unsigned long filename; offset:24; size:4; signed:0;
+ field:unsigned long flags; offset:28; size:4; signed:0;
+ field:unsigned long mode; offset:32; size:4; signed:0;
-print fmt: "(%lx) dfd=%lx filename=%lx flags=%lx mode=%lx", REC->ip, REC->dfd, REC->filename, REC->flags, REC->mode
+print fmt: "(%lx) dfd=%lx filename=%lx flags=%lx mode=%lx", REC->__probe_ip,
+REC->dfd, REC->filename, REC->flags, REC->mode
You can see that the event has 4 arguments as in the expressions you specified.
@@ -121,6 +123,12 @@ print fmt: "(%lx) dfd=%lx filename=%lx flags=%lx mode=%lx", REC->ip, REC->dfd, R
This clears all probe points.
+ Or,
+
+ echo -:myprobe >> kprobe_events
+
+ This clears probe points selectively.
+
Right after definition, each event is disabled by default. For tracing these
events, you need to enable it.
@@ -146,4 +154,3 @@ events, you need to enable it.
returns from SYMBOL(e.g. "sys_open+0x1b/0x1d <- do_sys_open" means kernel
returns from do_sys_open to sys_open+0x1b).
-