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authorMasami Hiramatsu <mhiramat@redhat.com>2009-10-07 18:27:59 -0400
committerFrederic Weisbecker <fweisbec@gmail.com>2009-10-12 23:30:29 +0200
commit2e06ff6389aedafc4a3a374344ac70672252f9b5 (patch)
treeec7c36f2da4e0a341da4ec79ac9aecfcb5a902af /Documentation/trace
parent99329c44f28a1b7ac83beebfb4319e612042e319 (diff)
tracing/kprobes: Make special variable names more self-explainable
Rename special variables to more self-explainable names as below: - $rv to $retval - $sa to $stack - $aN to $argN - $sN to $stackN 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: <20091007222759.1684.3319.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.txt22
1 files changed, 11 insertions, 11 deletions
diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index 4208253b5a5..15415243a9a 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -35,13 +35,13 @@ Synopsis of kprobe_events
MEMADDR : Address where the probe is inserted.
FETCHARGS : Arguments. Each probe can have up to 128 args.
- %REG : Fetch register REG
- @ADDR : Fetch memory at ADDR (ADDR should be in kernel)
+ %REG : Fetch register REG
+ @ADDR : Fetch memory at ADDR (ADDR should be in kernel)
@SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symbol)
- $sN : Fetch Nth entry of stack (N >= 0)
- $sa : Fetch stack address.
- $aN : Fetch function argument. (N >= 0)(*)
- $rv : Fetch return value.(**)
+ $stackN : Fetch Nth entry of stack (N >= 0)
+ $stack : Fetch stack address.
+ $argN : Fetch function argument. (N >= 0)(*)
+ $retval : Fetch return value.(**)
+|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***)
NAME=FETCHARG: Set NAME as the argument name of FETCHARG.
@@ -84,13 +84,13 @@ Usage examples
To add a probe as a new event, write a new definition to kprobe_events
as below.
- echo p:myprobe do_sys_open dfd=$a0 filename=$a1 flags=$a2 mode=$a3 > /sys/kernel/debug/tracing/kprobe_events
+ echo p:myprobe do_sys_open dfd=$arg0 filename=$arg1 flags=$arg2 mode=$arg3 > /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 >> /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.
@@ -137,11 +137,11 @@ 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
+ <...>-1447 [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) $retval=fffffffffffffffe
<...>-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
+ <...>-1447 [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $retval=3
<...>-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
+ <...>-1447 [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $retval=3
Each line shows when the kernel hits an event, and <- SYMBOL means kernel