On 2025/10/30 08:40, Masami Hiramatsu wrote:
> On Wed, 29 Oct 2025 10:15:14 +0800
> Menglong Dong <[email protected]> wrote:
>
> > For now, we will use ftrace for the fprobe if fp->exit_handler not exists
> > and CONFIG_DYNAMIC_FTRACE_WITH_REGS is enabled.
> >
> > However, CONFIG_DYNAMIC_FTRACE_WITH_REGS is not supported by some arch,
> > such as arm. What we need in the fprobe is the function arguments, so we
> > can use ftrace for fprobe if CONFIG_DYNAMIC_FTRACE_WITH_ARGS is enabled.
> >
> > Therefore, use ftrace if CONFIG_DYNAMIC_FTRACE_WITH_REGS or
> > CONFIG_DYNAMIC_FTRACE_WITH_ARGS enabled.
> >
> > Signed-off-by: Menglong Dong <[email protected]>
> > ---
> > kernel/trace/fprobe.c | 12 ++++++++----
> > 1 file changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
> > index ecd623eef68b..9fad0569f521 100644
> > --- a/kernel/trace/fprobe.c
> > +++ b/kernel/trace/fprobe.c
> > @@ -254,7 +254,11 @@ static inline int __fprobe_kprobe_handler(unsigned
> > long ip, unsigned long parent
> > return ret;
> > }
> >
> > -#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
> > +#if defined(CONFIG_DYNAMIC_FTRACE_WITH_ARGS) ||
> > defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS)
> > +#define FPROBE_USE_FTRACE
> > +#endif
> > +
> > +#ifdef FPROBE_USE_FTRACE
> > /* ftrace_ops callback, this processes fprobes which have only
> > entry_handler. */
> > static void fprobe_ftrace_entry(unsigned long ip, unsigned long parent_ip,
> > struct ftrace_ops *ops, struct ftrace_regs *fregs)
> > @@ -295,7 +299,7 @@ NOKPROBE_SYMBOL(fprobe_ftrace_entry);
> >
> > static struct ftrace_ops fprobe_ftrace_ops = {
> > .func = fprobe_ftrace_entry,
> > - .flags = FTRACE_OPS_FL_SAVE_REGS,
> > + .flags = FTRACE_OPS_FL_SAVE_ARGS,
> > };
> > static int fprobe_ftrace_active;
> >
> > @@ -349,7 +353,7 @@ static bool fprobe_is_ftrace(struct fprobe *fp)
> > {
> > return false;
> > }
> > -#endif
> > +#endif /* !FPROBE_USE_FTRACE */
> >
> > /* fgraph_ops callback, this processes fprobes which have exit_handler. */
> > static int fprobe_fgraph_entry(struct ftrace_graph_ent *trace, struct
> > fgraph_ops *gops,
> > @@ -599,7 +603,7 @@ static int fprobe_module_callback(struct notifier_block
> > *nb,
> > if (alist.index > 0) {
> > ftrace_set_filter_ips(&fprobe_graph_ops.ops,
> > alist.addrs, alist.index, 1, 0);
> > -#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
> > +#ifdef FPROBE_USE_FTRACE
> > ftrace_set_filter_ips(&fprobe_ftrace_ops,
> > alist.addrs, alist.index, 1, 0);
> > #endif
>
> Instead of introducing FPROBE_USE_FTRACE, I think it is better to add another
> wrapper to be called here.
Sounds better! I'll modify it in the next version.
Thanks!
Menglong Dong
>
> #if defined(CONFIG_DYNAMIC_FTRACE_WITH_ARGS) ||
> defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS)
>
> static void fprobe_set_ips(unsigned long *ips, unsigned int cnt, int remove,
> int reset)
> {
> ftrace_set_filter_ips(&fprobe_graph_ops.ops,
> alist.addrs, alist.index, 1, 0);
> ftrace_set_filter_ips(&fprobe_ftrace_ops,
> alist.addrs, alist.index, 1, 0);
> }
> ...
> #else
> static void fprobe_set_ips(unsigned long *ips, unsigned int cnt, int remove,
> int reset)
> {
> ftrace_set_filter_ips(&fprobe_graph_ops.ops,
> alist.addrs, alist.index, 1, 0);
> }
> #endif
>
> Thank you,
>
>
