Messages in this thread | | | Date | Thu, 18 Feb 2021 11:53:14 -0600 | From | Josh Poimboeuf <> | Subject | Re: [PATCH] objtool: Fix stack-swizzle for FRAME_POINTER=y |
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On Thu, Feb 18, 2021 at 05:21:31PM +0100, Peter Zijlstra wrote: > On Wed, Feb 10, 2021 at 08:01:23PM -0000, tip-bot2 for Peter Zijlstra wrote: > > objtool: Support stack-swizzle > > --- > Subject: objtool: Fix stack-swizzle for FRAME_POINTER=y > From: Peter Zijlstra <peterz@infradead.org> > Date: Thu Feb 18 17:14:10 CET 2021 > > When objtool encounters the stack-swizzle: > > mov %rsp, (%[tos]) > mov %[tos], %rsp > ... > pop %rsp > > Inside a FRAME_POINTER=y build, things go a little screwy because > clearly we're not adjusting the cfa->base. This then results in the > pop %rsp not being detected as a restore of cfa->base so it will turn > into a regular POP and offset the stack, resulting in: > > kernel/softirq.o: warning: objtool: do_softirq()+0xdb: return with modified stack frame > > Therefore, have "mov %[tos], %rsp" act like a PUSH (it sorta is > anyway) to balance the things out. We're not too concerned with the > actual stack_size for frame-pointer builds, since we don't generate > ORC data for them anyway. > > Fixes: aafeb14e9da2 ("objtool: Support stack-swizzle") > Reported-by: kernel test robot <lkp@intel.com> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
-- Josh
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