On Mon, 21 Oct 2019 17:34:19 +0100 Mark Rutland <[email protected]> wrote:
> Architectures may need to perform special initialization of ftrace > callsites, and today they do so by special-casing ftrace_make_nop() when > the expected branch address is MCOUNT_ADDR. In some cases (e.g. for > patchable-function-entry), we don't have an mcount-like symbol and don't > want a synthetic MCOUNT_ADDR, but we may need to perform some > initialization of callsites. > > To make it possible to separate initialization from runtime > modification, and to handle cases without an mcount-like symbol, this > patch adds an optional ftrace_init_nop() function that architectures can > implement, which does not pass a branch address. > > Where an architecture does not provide ftrace_init_nop(), we will fall > back to the existing behaviour of calling ftrace_make_nop() with > MCOUNT_ADDR. > > At the same time, ftrace_code_disable() is renamed to > ftrace_code_init_disabled() to make it clearer that it is intended to > intialize a callsite into a disabled state, and is not for disabling a > callsite that has been runtime enabled. To make the name even better, let's just rename it to: ftrace_nop_initialization() I think that may be the best description for it. > > Signed-off-by: Mark Rutland <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Steven Rostedt <[email protected]> > Cc: Torsten Duwe <[email protected]> > --- > kernel/trace/ftrace.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index f296d89be757..afd7e210e595 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -2493,15 +2493,22 @@ struct dyn_ftrace *ftrace_rec_iter_record(struct > ftrace_rec_iter *iter) > return &iter->pg->records[iter->index]; > } > > +#ifndef ftrace_init_nop > +static int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) > +{ > + return ftrace_make_nop(mod, rec, MCOUNT_ADDR); > +} > +#endif Can you place the above in the ftrace.h header. That's where that would belong. #ifndef ftrace_init_nop struct module; static inline int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) { return ftrace_make_nop(mod, rec, MCOUNT_ADDR); } #endif -- Steve > + > static int > -ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec) > +ftrace_code_init_disabled(struct module *mod, struct dyn_ftrace *rec) > { > int ret; > > if (unlikely(ftrace_disabled)) > return 0; > > - ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR); > + ret = ftrace_init_nop(mod, rec); > if (ret) { > ftrace_bug_type = FTRACE_BUG_INIT; > ftrace_bug(ret, rec); > @@ -2943,7 +2950,7 @@ static int ftrace_update_code(struct module *mod, > struct ftrace_page *new_pgs) > * to the NOP instructions. > */ > if (!__is_defined(CC_USING_NOP_MCOUNT) && > - !ftrace_code_disable(mod, p)) > + !ftrace_code_init_disabled(mod, p)) > break; > > update_cnt++;
