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SubjectRe: [tip:x86/pti 19/20] arch/x86/entry/entry_64.o: warning: objtool: paranoid_entry()+0x11: call without frame pointer save/setup
On Mon, Feb 12, 2018 at 07:33:27PM +0800, kbuild test robot wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/pti
> head: 5a10e729bc0aa9420a23a70b169eadd229c27bc1
> commit: f09d160992d129b6d8fada7543761d40f5b33596 [19/20] x86/entry/64: Get rid of the ALLOC_PT_GPREGS_ON_STACK and SAVE_AND_CLEAR_REGS macros
> config: x86_64-randconfig-s0-02121550 (attached as .config)
> compiler: gcc-6 (Debian 6.4.0-9) 6.4.0 20171026
> reproduce:
> git checkout f09d160992d129b6d8fada7543761d40f5b33596
> # save the attached .config to linux build tree
> make ARCH=x86_64
>
> All warnings (new ones prefixed by >>):
>
> >> arch/x86/entry/entry_64.o: warning: objtool: paranoid_entry()+0x11: call without frame pointer save/setup
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all Intel Corporation

Oops, looks like one of my suggested unwind hint changes wasn't so good
for the frame pointer case. The below should fix it. I'll submit a
proper patch in a little bit after running it through 0-day.

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index cfbf43366731..1c54204207d8 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1128,6 +1128,7 @@ idtentry machine_check do_mce has_error_code=0 paranoid=1
* Return: ebx=0: need swapgs on exit, ebx=1: otherwise
*/
ENTRY(paranoid_entry)
+ UNWIND_HINT_FUNC
cld
movl $1, %ebx
movl $MSR_GS_BASE, %ecx
@@ -1141,7 +1142,7 @@ ENTRY(paranoid_entry)
SAVE_AND_SWITCH_TO_KERNEL_CR3 scratch_reg=%rax save_reg=%r14

ret
-ENDPROC(paranoid_entry)
+END(paranoid_entry)

/*
* "Paranoid" exit path from exception stack. This is invoked
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