Re: [PATCH] stop_machine: Mark functions as notrace

[Guo Ren]

On Sat, Oct 31, 2020 at 8:28 AM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> On Fri, 30 Oct 2020 14:47:56 -0700
> Atish Patra <atishp@xxxxxxxxxxxxxx> wrote:
>
> > > Look at arm64, they __kprobes flag and I guess it would also prevent
> > > ftrace call site.
> > >
> >
> > Are you sure about that ? __kprobes puts the code in .kprobes.text section
> > which is under whitelist sections in recordmcount.pl & recordmcount.c.
>
> Correct, ftrace can trace functions marked with __kprobes. That said,
I guess wrong, thx for correct me.

> the instruction you are looking at here, is in a file that is
> blacklisted from recordmcount.
>
>   CFLAGS_REMOVE_insn.o = $(CC_FLAGS_FTRACE)
>
> All ftrace flags are removed from the compiling of insn.c, and every
> function in that file will not be traced.
Yes, arm64 prevents the whole file from ftrace. My patch just use
notrace flag setting on some functions.

@Atish How do think:
CFLAGS_REMOVE_cacheflush.o = $(CC_FLAGS_FTRACE)
CFLAGS_REMOVE_sbi.o = $(CC_FLAGS_FTRACE)

-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/