| Date | Fri, 25 Feb 2022 00:55:20 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH v2 12/39] x86/ibt,ftrace: Search for __fentry__ location |
| |
Hi Peter,
On Thu, 24 Feb 2022 15:51:50 +0100 Peter Zijlstra <peterz@infradead.org> wrote:
> Have ftrace_location() search the symbol for the __fentry__ location > when it isn't at func+0 and use this for {,un}register_ftrace_direct(). > > This avoids a whole bunch of assumptions about __fentry__ being at > func+0. > > Suggested-by: Steven Rostedt <rostedt@goodmis.org> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > --- > kernel/trace/ftrace.c | 30 ++++++++++++++++++++++++++++-- > 1 file changed, 28 insertions(+), 2 deletions(-) > > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -1578,7 +1578,24 @@ unsigned long ftrace_location_range(unsi > */ > unsigned long ftrace_location(unsigned long ip) > { > - return ftrace_location_range(ip, ip); > + struct dyn_ftrace *rec; > + unsigned long offset; > + unsigned long size; > + > + rec = lookup_rec(ip, ip); > + if (!rec) { > + if (!kallsyms_lookup_size_offset(ip, &size, &offset)) > + goto out; > + > + if (!offset)
Isn't this 'if (offset)' ?
> + rec = lookup_rec(ip - offset, (ip - offset) + size); > + } > + > + if (rec) > + return rec->ip; > + > +out: > + return 0; > }
Thank you,
> > /** > @@ -5110,11 +5127,16 @@ int register_ftrace_direct(unsigned long > struct ftrace_func_entry *entry; > struct ftrace_hash *free_hash = NULL; > struct dyn_ftrace *rec; > - int ret = -EBUSY; > + int ret = -ENODEV; > > mutex_lock(&direct_mutex); > > + ip = ftrace_location(ip); > + if (!ip) > + goto out_unlock; > + > /* See if there's a direct function at @ip already */ > + ret = -EBUSY; > if (ftrace_find_rec_direct(ip)) > goto out_unlock; > > @@ -5222,6 +5244,10 @@ int unregister_ftrace_direct(unsigned lo > > mutex_lock(&direct_mutex); > > + ip = ftrace_location(ip); > + if (!ip) > + goto out_unlock; > + > entry = find_direct_entry(&ip, NULL); > if (!entry) > goto out_unlock; > >
-- Masami Hiramatsu <mhiramat@kernel.org>
|