On Wed, 9 Aug 2023 12:31:00 +0200
Florent Revest <revest@xxxxxxxxxxxx> wrote:
> On Mon, Aug 7, 2023 at 8:49 AM Masami Hiramatsu (Google)
> <mhiramat@xxxxxxxxxx> wrote:
> >
> > From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
> >
> > Allow fprobe events to be enabled with CONFIG_DYNAMIC_FTRACE_WITH_ARGS.
> > With this change, fprobe events mostly use ftrace_regs instead of pt_regs.
> > Note that if the arch doesn't enable HAVE_PT_REGS_COMPAT_FTRACE_REGS,
> > fprobe events will not be able to use from perf.
>
> nit: "to be used from perf" ?
OK.
>
> > --- a/kernel/trace/trace_fprobe.c
> > +++ b/kernel/trace/trace_fprobe.c
> > @@ -132,25 +132,30 @@ static int
> > process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
> > void *base)
> > {
> > - struct pt_regs *regs = rec;
> > - unsigned long val;
> > + struct ftrace_regs *fregs = rec;
> > + unsigned long val, *stackp;
> > int ret;
> >
> > retry:
> > /* 1st stage: get value from context */
> > switch (code->op) {
> > case FETCH_OP_STACK:
> > - val = regs_get_kernel_stack_nth(regs, code->param);
> > + stackp = (unsigned long *)ftrace_regs_get_stack_pointer(fregs);
> > + if (((unsigned long)(stackp + code->param) & ~(THREAD_SIZE - 1)) ==
> > + ((unsigned long)stackp & ~(THREAD_SIZE - 1)))
>
> Maybe it'd be worth extracting a local
> "ftrace_regs_get_kernel_stack_nth_addr" helper function and/or
> "ftrace_regs_within_kernel_stack" ?
Yeah, maybe we can make it a generic inline function in linux/ftrace.h.
Thank you!
--
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
