On Mon, 19 Aug 2019 19:16:22 +0800 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 we want to remove MCOUNT_ADDR from all arch, I could cook patches for this.
