Hi, On Tue, 20 Aug 2019 11:27:38 +0200 (CEST) Miroslav Benes <mbe...@suse.cz> wrote: > > > Hi, > > On Mon, 19 Aug 2019, Jisheng Zhang wrote: > > > On some arch, the FTRACE_WITH_REGS is implemented with gcc's > > -fpatchable-function-entry (=2), gcc adds 2 NOPs at the beginning > > of each function, so this makes the MCOUNT_ADDR useless. In ftrace > > common framework, MCOUNT_ADDR is mostly used to "init" the nop, so > > let's introcude ftrace_call_init(). > > > > Signed-off-by: Jisheng Zhang <jisheng.zh...@synaptics.com> > > --- > > include/linux/ftrace.h | 1 + > > kernel/trace/ftrace.c | 4 ++++ > > 2 files changed, 5 insertions(+) > > > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > > index 8a8cb3c401b2..8175ffb671f0 100644 > > --- a/include/linux/ftrace.h > > +++ b/include/linux/ftrace.h > > @@ -458,6 +458,7 @@ extern void ftrace_regs_caller(void); > > extern void ftrace_call(void); > > extern void ftrace_regs_call(void); > > extern void mcount_call(void); > > +extern int ftrace_call_init(struct module *mod, struct dyn_ftrace *rec); > > > > void ftrace_modify_all_code(int command); > > > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > > index eca34503f178..9df5a66a6811 100644 > > --- a/kernel/trace/ftrace.c > > +++ b/kernel/trace/ftrace.c > > @@ -2500,7 +2500,11 @@ ftrace_code_disable(struct module *mod, struct > > dyn_ftrace *rec) > > if (unlikely(ftrace_disabled)) > > return 0; > > > > +#ifdef MCOUNT_ADDR > > ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR); > > +#else > > + ret = ftrace_call_init(mod, rec); > > +#endif > > if (ret) { > > ftrace_bug_type = FTRACE_BUG_INIT; > > ftrace_bug(ret, rec); > > I may be missing something, but the patch does not seem to be complete. > There is no ftrace_call_init() implemented. MCOUNT_ADDR is still defined, > so it does not change much. I don't think it is what Mark had in his mind. >
Yes, except arm64, MCOUNT_ADDR is still defined in other arch. If we want to remove MCOUNT_ADDR from all arch, I will cook patches for this purpose. Thanks