This is a note to let you know that I've just added the patch titled
tracing: Handle old buffer mappings for event strings and functions
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tracing-handle-old-buffer-mappings-for-event-strings.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 691cb0f3ccc423996a2230d9535f9d9e821d8b7c
Author: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Date: Wed Jun 12 19:19:45 2024 -0400
tracing: Handle old buffer mappings for event strings and functions
[ Upstream commit 07714b4bb3f9800261c8b4b2f47e9010ed60979d ]
Use the saved text_delta and data_delta of a persistent memory mapped ring
buffer that was saved from a previous boot, and use the delta in the trace
event print output so that strings and functions show up normally.
That is, for an event like trace_kmalloc() that prints the callsite via
"%pS", if it used the address saved in the ring buffer it will not match
the function that was saved in the previous boot if the kernel remaps
itself between boots.
For RCU events that point to saved static strings where only the address
of the string is saved in the ring buffer, it too will be adjusted to
point to where the string is on the current boot.
Link: https://lkml.kernel.org/r/20240612232026.821020753@xxxxxxxxxxx
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Vincent Donnefort <vdonnefort@xxxxxxxxxx>
Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vineeth Pillai <vineeth@xxxxxxxxxxxxxxx>
Cc: Youssef Esmat <youssefesmat@xxxxxxxxxx>
Cc: Beau Belgrave <beaub@xxxxxxxxxxxxxxxxxxx>
Cc: Alexander Graf <graf@xxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: Ross Zwisler <zwisler@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Stable-dep-of: afd2627f727b ("tracing: Check "%s" dereference via the field and not the TP_printk format")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d9406a1f8795..2a45efc4e417 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3858,8 +3858,11 @@ static void test_can_verify(void)
void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
va_list ap)
{
+ long text_delta = iter->tr->text_delta;
+ long data_delta = iter->tr->data_delta;
const char *p = fmt;
const char *str;
+ bool good;
int i, j;
if (WARN_ON_ONCE(!fmt))
@@ -3878,7 +3881,10 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
j = 0;
- /* We only care about %s and variants */
+ /*
+ * We only care about %s and variants
+ * as well as %p[sS] if delta is non-zero
+ */
for (i = 0; p[i]; i++) {
if (i + 1 >= iter->fmt_size) {
/*
@@ -3907,6 +3913,11 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
}
if (p[i+j] == 's')
break;
+
+ if (text_delta && p[i+1] == 'p' &&
+ ((p[i+2] == 's' || p[i+2] == 'S')))
+ break;
+
star = false;
}
j = 0;
@@ -3920,6 +3931,24 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
iter->fmt[i] = '\0';
trace_seq_vprintf(&iter->seq, iter->fmt, ap);
+ /* Add delta to %pS pointers */
+ if (p[i+1] == 'p') {
+ unsigned long addr;
+ char fmt[4];
+
+ fmt[0] = '%';
+ fmt[1] = 'p';
+ fmt[2] = p[i+2]; /* Either %ps or %pS */
+ fmt[3] = '\0';
+
+ addr = va_arg(ap, unsigned long);
+ addr += text_delta;
+ trace_seq_printf(&iter->seq, fmt, (void *)addr);
+
+ p += i + 3;
+ continue;
+ }
+
/*
* If iter->seq is full, the above call no longer guarantees
* that ap is in sync with fmt processing, and further calls
@@ -3938,6 +3967,14 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
/* The ap now points to the string data of the %s */
str = va_arg(ap, const char *);
+ good = trace_safe_str(iter, str, star, len);
+
+ /* Could be from the last boot */
+ if (data_delta && !good) {
+ str += data_delta;
+ good = trace_safe_str(iter, str, star, len);
+ }
+
/*
* If you hit this warning, it is likely that the
* trace event in question used %s on a string that
@@ -3947,8 +3984,7 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt,
* instead. See samples/trace_events/trace-events-sample.h
* for reference.
*/
- if (WARN_ONCE(!trace_safe_str(iter, str, star, len),
- "fmt: '%s' current_buffer: '%s'",
+ if (WARN_ONCE(!good, "fmt: '%s' current_buffer: '%s'",
fmt, seq_buf_str(&iter->seq.seq))) {
int ret;
