diff options
| author | Steven Rostedt (Google) <rostedt@goodmis.org> | 2023-01-24 09:56:53 -0500 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2023-03-21 14:00:10 -0400 |
| commit | e11b521a7b69c2621bb2e5920bb96f6d2facdc7e (patch) | |
| tree | 9c56b9fb5c5536911e206cf8466d4afac640b77f /include/linux/ftrace.h | |
| parent | 8328e36da9cd8cb051394630e910cbb461f7e3ec (diff) | |
ftrace: Show a list of all functions that have ever been enabled
When debugging a crash that appears to be related to ftrace, but not for
sure, it is useful to know if a function was ever enabled by ftrace or
not. It could be that a BPF program was attached to it, or possibly a live
patch.
We are having crashes in the field where this information is not always
known. But having ftrace set a flag if a function has ever been attached
since boot up helps tremendously in trying to know if a crash had to do
with something using ftrace.
For analyzing crashes, the use of a kdump image can have access to the
flags. When looking at issues where the kernel did not panic, the
touched_functions file can simply be used.
Link: https://lore.kernel.org/linux-trace-kernel/20230124095653.6fd1640e@gandalf.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Chris Li <chriscli@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'include/linux/ftrace.h')
| -rw-r--r-- | include/linux/ftrace.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 931f3d904529..327046f1278d 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -548,6 +548,7 @@ bool is_ftrace_trampoline(unsigned long addr); * DIRECT - there is a direct function to call * CALL_OPS - the record can use callsite-specific ops * CALL_OPS_EN - the function is set up to use callsite-specific ops + * TOUCHED - A callback was added since boot up * * When a new ftrace_ops is registered and wants a function to save * pt_regs, the rec->flags REGS is set. When the function has been @@ -567,9 +568,10 @@ enum { FTRACE_FL_DIRECT_EN = (1UL << 23), FTRACE_FL_CALL_OPS = (1UL << 22), FTRACE_FL_CALL_OPS_EN = (1UL << 21), + FTRACE_FL_TOUCHED = (1UL << 20), }; -#define FTRACE_REF_MAX_SHIFT 21 +#define FTRACE_REF_MAX_SHIFT 20 #define FTRACE_REF_MAX ((1UL << FTRACE_REF_MAX_SHIFT) - 1) #define ftrace_rec_count(rec) ((rec)->flags & FTRACE_REF_MAX) @@ -628,6 +630,7 @@ enum { FTRACE_ITER_PROBE = (1 << 4), FTRACE_ITER_MOD = (1 << 5), FTRACE_ITER_ENABLED = (1 << 6), + FTRACE_ITER_TOUCHED = (1 << 7), }; void arch_ftrace_update_code(int command); |