x86/kvm: Add stack frame dependency to fastop() inline asm

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The kbuild test robot reported this objtool warning [1]:

  arch/x86/kvm/emulate.o: warning: objtool: fastop()+0x69: call without frame pointer save/setup

The issue seems to be caused by CONFIG_PROFILE_ALL_BRANCHES.  With that
option, for some reason gcc decides not to create a stack frame in
fastop() before doing the inline asm call, which can result in a bad
stack trace.

Force a stack frame to be created if CONFIG_FRAME_POINTER is enabled by
listing the stack pointer as an output operand for the inline asm
statement.

This change has no effect for !CONFIG_PROFILE_ALL_BRANCHES.

[1] https://lists.01.org/pipermail/kbuild-all/2016-March/018249.html

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

...

This commit is contained in:

Josh Poimboeuf 2016-03-09 12:59:50 -06:00 • committed by Paolo Bonzini

parent 5e1b59abef

commit 4548f63e65

1 changed files with 5 additions and 1 deletions

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arch/x86/kvm/emulate.c

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