tracing/probe: Add immediate string parameter support

Browse source

Add immediate string parameter (\"string") support to
probe events. This allows you to specify an immediate
(or dummy) parameter instead of fetching a string from
memory.

This feature looks odd, but imagine that you put a probe
on a code to trace some string data. If the code is
compiled into 2 instructions and 1 instruction has a
string on memory but other has no string since it is
optimized out. In that case, you can not fold those into
one event, even if ftrace supported multiple probes on
one event. With this feature, you can set a dummy string
like foo=\"(optimized)":string instead of something
like foo=+0(+0(%bp)):string.

Link: http://lkml.kernel.org/r/156095691687.28024.13372712423865047991.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

...

This commit is contained in:

Masami Hiramatsu 2019-06-20 00:08:37 +09:00 • committed by Steven Rostedt (VMware)

parent 6218bf9f4d

commit a42e3c4de9

5 changed files with 51 additions and 15 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

2

kernel/trace/trace.c

View file

3

kernel/trace/trace_kprobe.c

View file

56

kernel/trace/trace_probe.c

View file

2

kernel/trace/trace_probe.h

View file

3

kernel/trace/trace_uprobe.c

View file