From 87aaff2ae09036cf699fde20dfd52ce7d3c8eabe Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Sun, 28 Feb 2016 22:22:40 -0600 Subject: x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard objtool reports the following warning for kretprobe_trampoline(): arch/x86/kernel/kprobes/core.o: warning: objtool: kretprobe_trampoline()+0x20: call without frame pointer save/setup kretprobes are a special case where the stack is intentionally wrong. The return address isn't known at the beginning of the trampoline, so the stack frame can't be set up properly before it calls trampoline_handler(). Because kretprobe handlers don't sleep, the frame pointer doesn't *have* to be accurate in the trampoline. So it's ok to tell objtool to ignore it. This results in no actual changes to the generated code. Signed-off-by: Josh Poimboeuf Cc: Ananth N Mavinakayanahalli Cc: Andrew Morton Cc: Andy Lutomirski Cc: Anil S Keshavamurthy Cc: Arnaldo Carvalho de Melo Cc: Bernd Petrovitsch Cc: Borislav Petkov Cc: Chris J Arges Cc: David S. Miller Cc: Jiri Slaby Cc: Linus Torvalds Cc: Masami Hiramatsu Cc: Michal Marek Cc: Namhyung Kim Cc: Pedro Alves Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/7eaf37de52456ff822ffc86b928edb5d48a40ef1.1456719558.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/kprobes/core.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch') diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 48acaac35bd2..ae703acb85c1 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -49,6 +49,7 @@ #include #include #include +#include #include #include @@ -703,6 +704,7 @@ asm( ".size kretprobe_trampoline, .-kretprobe_trampoline\n" ); NOKPROBE_SYMBOL(kretprobe_trampoline); +STACK_FRAME_NON_STANDARD(kretprobe_trampoline); /* * Called from kretprobe_trampoline -- cgit v1.2.3