lkml.org 
[lkml]   [2022]   [Aug]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[for-linus][PATCH 07/10] tracing/eprobes: Fix reading of string fields
From: "Steven Rostedt (Google)" <rostedt@goodmis.org>

Currently when an event probe (eprobe) hooks to a string field, it does
not display it as a string, but instead as a number. This makes the field
rather useless. Handle the different kinds of strings, dynamic, static,
relational/dynamic etc.

Now when a string field is used, the ":string" type can be used to display
it:

echo "e:sw sched/sched_switch comm=$next_comm:string" > dynamic_events

Cc: stable@vger.kernel.org
Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/trace_eprobe.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
index 550671985fd1..a1d3423ab74f 100644
--- a/kernel/trace/trace_eprobe.c
+++ b/kernel/trace/trace_eprobe.c
@@ -311,6 +311,27 @@ static unsigned long get_event_field(struct fetch_insn *code, void *rec)

addr = rec + field->offset;

+ if (is_string_field(field)) {
+ switch (field->filter_type) {
+ case FILTER_DYN_STRING:
+ val = (unsigned long)(rec + (*(unsigned int *)addr & 0xffff));
+ break;
+ case FILTER_RDYN_STRING:
+ val = (unsigned long)(addr + (*(unsigned int *)addr & 0xffff));
+ break;
+ case FILTER_STATIC_STRING:
+ val = (unsigned long)addr;
+ break;
+ case FILTER_PTR_STRING:
+ val = (unsigned long)(*(char *)addr);
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ return 0;
+ }
+ return val;
+ }
+
switch (field->size) {
case 1:
if (field->is_signed)
--
2.35.1
\
 
 \ /
  Last update: 2022-08-21 02:10    [W:0.071 / U:0.504 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site