diff options
| author | Masami Hiramatsu (Google) <mhiramat@kernel.org> | 2023-06-06 21:39:55 +0900 |
|---|---|---|
| committer | Masami Hiramatsu (Google) <mhiramat@kernel.org> | 2023-06-06 21:39:55 +0900 |
| commit | 334e5519c3757019cc591d4539d5aca199bdb114 (patch) | |
| tree | bac0d8e021f510ec70176ad566764528470a11c1 /kernel/trace/trace_probe.h | |
| parent | 30460c21ed40a10bf541c4e93ba5e80bb4aac5da (diff) | |
tracing/probes: Add fprobe events for tracing function entry and exit.
Add fprobe events for tracing function entry and exit instead of kprobe
events. With this change, we can continue to trace function entry/exit
even if the CONFIG_KPROBES_ON_FTRACE is not available. Since
CONFIG_KPROBES_ON_FTRACE requires the CONFIG_DYNAMIC_FTRACE_WITH_REGS,
it is not available if the architecture only supports
CONFIG_DYNAMIC_FTRACE_WITH_ARGS. And that means kprobe events can not
probe function entry/exit effectively on such architecture.
But this can be solved if the dynamic events supports fprobe events.
The fprobe event is a new dynamic events which is only for the function
(symbol) entry and exit. This event accepts non register fetch arguments
so that user can trace the function arguments and return values.
The fprobe events syntax is here;
f[:[GRP/][EVENT]] FUNCTION [FETCHARGS]
f[MAXACTIVE][:[GRP/][EVENT]] FUNCTION%return [FETCHARGS]
E.g.
# echo 'f vfs_read $arg1' >> dynamic_events
# echo 'f vfs_read%return $retval' >> dynamic_events
# cat dynamic_events
f:fprobes/vfs_read__entry vfs_read arg1=$arg1
f:fprobes/vfs_read__exit vfs_read%return arg1=$retval
# echo 1 > events/fprobes/enable
# head -n 20 trace | tail
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
sh-142 [005] ...1. 448.386420: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
sh-142 [005] ..... 448.386436: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1
sh-142 [005] ...1. 448.386451: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
sh-142 [005] ..... 448.386458: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1
sh-142 [005] ...1. 448.386469: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
sh-142 [005] ..... 448.386476: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1
sh-142 [005] ...1. 448.602073: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
sh-142 [005] ..... 448.602089: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1
Link: https://lore.kernel.org/all/168507469754.913472.6112857614708350210.stgit@mhiramat.roam.corp.google.com/
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/all/202302011530.7vm4O8Ro-lkp@intel.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Diffstat (limited to 'kernel/trace/trace_probe.h')
| -rw-r--r-- | kernel/trace/trace_probe.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index 5df59714f9f5..8f4f23e8b234 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -367,6 +367,7 @@ int trace_probe_print_args(struct trace_seq *s, struct probe_arg *args, int nr_a #define TPARG_FL_FENTRY BIT(2) #define TPARG_FL_TPOINT BIT(3) #define TPARG_FL_USER BIT(4) +#define TPARG_FL_FPROBE BIT(5) #define TPARG_FL_MASK GENMASK(4, 0) extern int traceprobe_parse_probe_arg(struct trace_probe *tp, int i, @@ -409,7 +410,7 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call, C(REFCNT_OPEN_BRACE, "Reference counter brace is not closed"), \ C(BAD_REFCNT_SUFFIX, "Reference counter has wrong suffix"), \ C(BAD_UPROBE_OFFS, "Invalid uprobe offset"), \ - C(MAXACT_NO_KPROBE, "Maxactive is not for kprobe"), \ + C(BAD_MAXACT_TYPE, "Maxactive is only for function exit"), \ C(BAD_MAXACT, "Invalid maxactive number"), \ C(MAXACT_TOO_BIG, "Maxactive is too big"), \ C(BAD_PROBE_ADDR, "Invalid probed address or symbol"), \ |