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authorJosh Poimboeuf <jpoimboe@redhat.com>2016-02-28 22:22:38 -0600
committerIngo Molnar <mingo@kernel.org>2016-02-29 08:35:11 +0100
commit8e05e96ac949c80704d0a38420bf60dcf18c938f (patch)
treebd22d6558a43a69f3881b5d7b43c8abcc2859eaf /kernel
parent39853cc0cdcf1b11f00f7f81e2f515a4d68ed209 (diff)
downloadop-kernel-dev-8e05e96ac949c80704d0a38420bf60dcf18c938f.zip
op-kernel-dev-8e05e96ac949c80704d0a38420bf60dcf18c938f.tar.gz
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=n1pKBZfFPQUFg@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 <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/91190e324ebd7fcd01748d508d0dfd4693e84d91.1456719558.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c2
1 files changed, 2 insertions, 0 deletions
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)
{
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