Commit-ID: 8e05e96ac949c80704d0a38420bf60dcf18c938f Gitweb: http://git.kernel.org/tip/8e05e96ac949c80704d0a38420bf60dcf18c938f Author: Josh Poimboeuf <jpoim...@redhat.com> AuthorDate: Sun, 28 Feb 2016 22:22:38 -0600 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Mon, 29 Feb 2016 08:35:11 +0100
sched: Mark __schedule() stack frame as non-standard objtool reports the following warnings for __schedule(): kernel/sched/core.o: warning: objtool:__schedule()+0x3c0: duplicate frame pointer save kernel/sched/core.o: warning: objtool:__schedule()+0x3fd: sibling call from callable instruction with changed frame pointer kernel/sched/core.o: warning: objtool:__schedule()+0x40a: call without frame pointer save/setup kernel/sched/core.o: warning: objtool:__schedule()+0x7fd: frame pointer state mismatch kernel/sched/core.o: warning: objtool:__schedule()+0x421: frame pointer state mismatch Basically it's confused by two unusual attributes of the switch_to() macro: 1. It saves prev's frame pointer to the old stack and restores next's frame pointer from the new stack. 2. For new tasks it jumps directly to ret_from_fork. Eventually it would probably be a good idea to clean up the ret_from_fork hack so that new tasks are created with a valid initial stack, as suggested by Andy: https://lkml.kernel.org/r/CALCETrWsqCw4L1qKO9j9L5F+4ED4viuLQTFc=n1pkbzffpq...@mail.gmail.com Then __schedule() could return normally into the new code and objtool hopefully wouldn't have a problem anymore. In the meantime, mark its stack frame as non-standard so we can have a baseline with no objtool warnings. The marker also serves as a reminder that this code could be improved a bit. Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Andy Lutomirski <l...@kernel.org> Cc: Arnaldo Carvalho de Melo <a...@kernel.org> Cc: Bernd Petrovitsch <be...@petrovitsch.priv.at> Cc: Borislav Petkov <b...@alien8.de> Cc: Chris J Arges <chris.j.ar...@canonical.com> Cc: Jiri Slaby <jsl...@suse.cz> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Michal Marek <mma...@suse.cz> Cc: Namhyung Kim <namhy...@gmail.com> Cc: Pedro Alves <pal...@redhat.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: live-patch...@vger.kernel.org Link: http://lkml.kernel.org/r/91190e324ebd7fcd01748d508d0dfd4693e84d91.1456719558.git.jpoim...@redhat.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/sched/core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9503d59..641043d 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -74,6 +74,7 @@ #include <linux/binfmts.h> #include <linux/context_tracking.h> #include <linux/compiler.h> +#include <linux/frame.h> #include <asm/switch_to.h> #include <asm/tlb.h> @@ -3288,6 +3289,7 @@ static void __sched notrace __schedule(bool preempt) balance_callback(rq); } +STACK_FRAME_NON_STANDARD(__schedule); /* switch_to() */ static inline void sched_submit_work(struct task_struct *tsk) {
