diff options
| author | Masami Hiramatsu | 2009-10-07 18:27:40 -0400 |
|---|---|---|
| committer | Frederic Weisbecker | 2009-10-12 19:21:35 +0200 |
| commit | 405b2651e4bedf8d3932b64cad649b4d26b067f5 (patch) | |
| tree | 2d0612b11756a450f31157693fd15858e98d66a2 /Documentation/trace | |
| parent | 88f70d7590538e427c8405a2e02ac2624847386c (diff) | |
tracing/kprobes: Add $ prefix to special variables
Add $ prefix to the special variables(e.g. sa, rv) of kprobe-tracer.
This resolves consistency issues between kprobe_events and perf-kprobe.
The main goal is to avoid conflicts between local variable names of
probed functions, used by perf probe, and special variables used
in the kprobe event creation interface (stack values, etc...) and
also available from perf probe.
ie: we don't want rv (return value) to conflict with a local variable
named rv in a probed function.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
LKML-Reference: <20091007222740.1684.91170.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Diffstat (limited to 'Documentation/trace')
| -rw-r--r-- | Documentation/trace/kprobetrace.txt | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt index 9b8f7c6040a7..33f531858c56 100644 --- a/Documentation/trace/kprobetrace.txt +++ b/Documentation/trace/kprobetrace.txt @@ -36,13 +36,13 @@ Synopsis of kprobe_events FETCHARGS : Arguments. Each probe can have up to 128 args. %REG : Fetch register REG - sN : Fetch Nth entry of stack (N >= 0) - sa : Fetch stack address. @ADDR : Fetch memory at ADDR (ADDR should be in kernel) @SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symbol) - aN : Fetch function argument. (N >= 0)(*) - rv : Fetch return value.(**) - ra : Fetch return address.(**) + $sN : Fetch Nth entry of stack (N >= 0) + $sa : Fetch stack address. + $aN : Fetch function argument. (N >= 0)(*) + $rv : Fetch return value.(**) + $ra : Fetch return address.(**) +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***) NAME=FETCHARG: Set NAME as the argument name of FETCHARG. @@ -85,13 +85,13 @@ Usage examples To add a probe as a new event, write a new definition to kprobe_events as below. - echo p:myprobe do_sys_open dfd=a0 filename=a1 flags=a2 mode=a3 > /sys/kernel/debug/tracing/kprobe_events + echo p:myprobe do_sys_open dfd=$a0 filename=$a1 flags=$a2 mode=$a3 > /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. - echo r:myretprobe do_sys_open rv ra >> /sys/kernel/debug/tracing/kprobe_events + echo r:myretprobe do_sys_open $rv $ra >> /sys/kernel/debug/tracing/kprobe_events This sets a kretprobe on the return point of do_sys_open() function with recording return value and return address as "myretprobe" event. @@ -138,11 +138,11 @@ events, you need to enable it. # TASK-PID CPU# TIMESTAMP FUNCTION # | | | | | <...>-1447 [001] 1038282.286875: myprobe: (do_sys_open+0x0/0xd6) dfd=3 filename=7fffd1ec4440 flags=8000 mode=0 - <...>-1447 [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) rv=fffffffffffffffe ra=ffffffff81367a3a + <...>-1447 [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) $rv=fffffffffffffffe $ra=ffffffff81367a3a <...>-1447 [001] 1038282.286885: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=40413c flags=8000 mode=1b6 - <...>-1447 [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) rv=3 ra=ffffffff81367a3a + <...>-1447 [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3 $ra=ffffffff81367a3a <...>-1447 [001] 1038282.286969: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=4041c6 flags=98800 mode=10 - <...>-1447 [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) rv=3 ra=ffffffff81367a3a + <...>-1447 [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3 $ra=ffffffff81367a3a Each line shows when the kernel hits an event, and <- SYMBOL means kernel |