summaryrefslogtreecommitdiff
path: root/kernel
diff options
context:
space:
mode:
authorSteven Rostedt (Google) <rostedt@goodmis.org>2023-05-02 21:32:33 -0400
committerSteven Rostedt (Google) <rostedt@goodmis.org>2023-05-05 11:09:25 -0400
commit6ce2c04fcbcaa5eb086e5142ab359be306cbc3e1 (patch)
treee404fa564374277c40bff95682f3477de87fbae9 /kernel
parent4f94559f40ad06d627c0fdfc3319cec778a2845b (diff)
downloadlwn-6ce2c04fcbcaa5eb086e5142ab359be306cbc3e1.tar.gz
lwn-6ce2c04fcbcaa5eb086e5142ab359be306cbc3e1.zip
ftrace: Add MODIFIED flag to show if IPMODIFY or direct was attached
If a function had ever had IPMODIFY or DIRECT attached to it, where this is how live kernel patching and BPF overrides work, mark them and display an "M" in the enabled_functions and touched_functions files. This can be used for debugging. If a function had been modified and later there's a bug in the code related to that function, this can be used to know if the cause is possibly from a live kernel patch or a BPF program that changed the behavior of the code. Also update the documentation on the enabled_functions and touched_functions output, as it was missing direct callers and CALL_OPS. And include this new modify attribute. Link: https://lore.kernel.org/linux-trace-kernel/20230502213233.004e3ae4@gandalf.local.home Cc: Mark Rutland <mark.rutland@arm.com> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/ftrace.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index db8532a4d5c8..885845fc851d 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -46,7 +46,8 @@
#include "trace_stat.h"
/* Flags that do not get reset */
-#define FTRACE_NOCLEAR_FLAGS (FTRACE_FL_DISABLED | FTRACE_FL_TOUCHED)
+#define FTRACE_NOCLEAR_FLAGS (FTRACE_FL_DISABLED | FTRACE_FL_TOUCHED | \
+ FTRACE_FL_MODIFIED)
#define FTRACE_INVALID_FUNCTION "__ftrace_invalid_address__"
@@ -2273,6 +2274,10 @@ static int ftrace_check_record(struct dyn_ftrace *rec, bool enable, bool update)
rec->flags &= ~FTRACE_FL_TRAMP_EN;
}
+ /* Keep track of anything that modifies the function */
+ if (rec->flags & (FTRACE_FL_DIRECT | FTRACE_FL_IPMODIFY))
+ rec->flags |= FTRACE_FL_MODIFIED;
+
if (flag & FTRACE_FL_DIRECT) {
/*
* If there's only one user (direct_ops helper)
@@ -3866,12 +3871,13 @@ static int t_show(struct seq_file *m, void *v)
if (iter->flags & (FTRACE_ITER_ENABLED | FTRACE_ITER_TOUCHED)) {
struct ftrace_ops *ops;
- seq_printf(m, " (%ld)%s%s%s%s",
+ seq_printf(m, " (%ld)%s%s%s%s%s",
ftrace_rec_count(rec),
rec->flags & FTRACE_FL_REGS ? " R" : " ",
rec->flags & FTRACE_FL_IPMODIFY ? " I" : " ",
rec->flags & FTRACE_FL_DIRECT ? " D" : " ",
- rec->flags & FTRACE_FL_CALL_OPS ? " O" : " ");
+ rec->flags & FTRACE_FL_CALL_OPS ? " O" : " ",
+ rec->flags & FTRACE_FL_MODIFIED ? " M " : " ");
if (rec->flags & FTRACE_FL_TRAMP_EN) {
ops = ftrace_find_tramp_ops_any(rec);
if (ops) {