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| author |   Masami Hiramatsu <mhiramat@kernel.org> | 2018-04-25 21:21:26 +0900 |
|---|---|---|
| committer |   Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-10-10 22:19:11 -0400 |
| commit | a1303af5d79eb13a658633a9fb0ce3aed0f7decf (patch) | |
| tree | 06ab7627ff3bec7afcba894432a5798babd3e0bc /Documentation/trace | |
| parent | x86: ptrace: Add function argument access API (diff) | |
| download | linux-dev-a1303af5d79eb13a658633a9fb0ce3aed0f7decf.tar.xz linux-dev-a1303af5d79eb13a658633a9fb0ce3aed0f7decf.zip | |
tracing: probeevent: Add $argN for accessing function args
Add $argN special fetch variable for accessing function
arguments. This allows user to trace the Nth argument easily
at the function entry.
Note that this returns most probably assignment of registers
and stacks. In some case, it may not work well. If you need
to access correct registers or stacks you should use perf-probe.
Link: http://lkml.kernel.org/r/152465888632.26224.3412465701570253696.stgit@devbox
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'Documentation/trace')
| -rw-r--r-- | Documentation/trace/kprobetrace.rst | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst index 2dfed7a1ea6f..47e765c2f2c3 100644 --- a/Documentation/trace/kprobetrace.rst +++ b/Documentation/trace/kprobetrace.rst @@ -45,16 +45,18 @@ 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. - $retval : Fetch return value.(*) + $argN : Fetch the Nth function argument. (N >= 1) (\*1) + $retval : Fetch return value.(\*2) $comm : Fetch current task comm. - +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**) + +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(\*3) NAME=FETCHARG : Set NAME as the argument name of FETCHARG. FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types (u8/u16/u32/u64/s8/s16/s32/s64), hexadecimal types (x8/x16/x32/x64), "string" and bitfield are supported. - (*) only for return probe. - (**) this is useful for fetching a field of data structures. + (\*1) only for the probe on function entry (offs == 0). + (\*2) only for return probe. + (\*3) this is useful for fetching a field of data structures. Types ----- |