Messages in this thread | | | Date | Fri, 6 Nov 2015 15:42:58 +0000 | From | Will Deacon <> | Subject | Re: [PATCH] arm64: remove redundant FRAME_POINTER kconfig option |
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On Fri, Nov 06, 2015 at 12:50:02PM +0000, Mark Rutland wrote: > On Fri, Nov 06, 2015 at 12:30:09PM +0000, Will Deacon wrote: > > On Wed, Nov 04, 2015 at 09:37:51AM -0800, Yang Shi wrote: > > > FRAME_POINTER is defined in lib/Kconfig.debug, it is unnecessary to redefine > > > it in arch/arm64/Kconfig.debug. > > > > It might be worth noting that this adds a dependency on DEBUG_KERNEL > > for building with frame pointers. I'm ok with that (it appears to be > > enabled in defconfig and follows the vast majority of other archs) but > > it is a change in behaviour. > > > > With that: > > > > Acked-by: Will Deacon <will.deacon@arm.com> > > The code in arch/arm64/kernel/stacktrace.c assumes we have frame > pointers regardless of FRAME_POINTER. Depending on what the compiler > decides to use x29 for, we could get some weird fake unwinding and/or > dodgy memory accesses. > > I think we should first audit the uses of frame pointers to ensure that > they are guarded for !FRAME_POINTER.
Good point. The perf callchain code suffers from a similar issue.
Will
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