On Thu, 29 Feb 2024 16:13:20 +0900
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> wrote:
> On Thu, 29 Feb 2024 15:38:55 +0900
> Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> wrote:
>
> > Hmm, this seems arch_rethook_trampoline caused the issue.
> >
> > And curiously, it depends on the number of stored data.
> >
> > OK:
> > /sys/kernel/tracing # echo 'f vfs_read%return $arg1 $arg2 $arg3' >> dynamic_events
> > /sys/kernel/tracing # echo 1 > events/fprobes/enable
> >
> > NG:
> > /sys/kernel/tracing # echo 'f vfs_read%return $arg1 $arg2 $arg3 $arg4' >> dynamic_events
> > /sys/kernel/tracing # echo 1 > events/fprobes/enable
> >
> > I also confirmed that on 'vfs_write' caused the same result. 3 arguments(24 bytes) is OK,
> > but 4 arguments (32bytes) is NG.
>
> And this may be the fprobe bug. kretprobe events doesn't show this issue.
>
> OK:
> /sys/kernel/tracing # echo 'r vfs_read $arg*' >> kprobe_events
> /sys/kernel/tracing # echo 1 > events/kprobes/enable
>
> But this is strange because both uses same rethook...
Lol, I haven't allocate the entry data size when initialize rethook.
That's a bug.
Please try below.
diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index 6cd2a4e3afb8..9ff018245840 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -189,9 +189,6 @@ static int fprobe_init_rethook(struct fprobe *fp, int num)
{
int size;
- if (num <= 0)
- return -EINVAL;
-
if (!fp->exit_handler) {
fp->rethook = NULL;
return 0;
@@ -199,15 +196,16 @@ static int fprobe_init_rethook(struct fprobe *fp, int num)
/* Initialize rethook if needed */
if (fp->nr_maxactive)
- size = fp->nr_maxactive;
+ num = fp->nr_maxactive;
else
- size = num * num_possible_cpus() * 2;
- if (size <= 0)
+ num *= num_possible_cpus() * 2;
+ if (num <= 0)
return -EINVAL;
+ size = sizeof(struct fprobe_rethook_node) + fp->entry_data_size;
+
/* Initialize rethook */
- fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler,
- sizeof(struct fprobe_rethook_node), size);
+ fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler, size, num);
if (IS_ERR(fp->rethook))
return PTR_ERR(fp->rethook);
--
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
