4.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
commit b3ccefaed922529e6a67de7b30af5aa38c76ace9 upstream.
With the following commit:
f09d160992d1 ("x86/entry/64: Get rid of the ALLOC_PT_GPREGS_ON_STACK and SAVE_AND_CLEAR_REGS macros")
... one of my suggested improvements triggered a frame pointer warning:
arch/x86/entry/entry_64.o: warning: objtool: paranoid_entry()+0x11: call without frame pointer save/setup
The warning is correct for the build-time code, but it's actually not
relevant at runtime because of paravirt patching. The paravirt swapgs
call gets replaced with either a SWAPGS instruction or NOPs at runtime.
Go back to the previous behavior by removing the ELF function annotation
for paranoid_entry() and adding an unwind hint, which effectively
silences the warning.
Reported-by: kbuild test robot <fengguang.wu@xxxxxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: kbuild-all@xxxxxx
Cc: tipbuild@xxxxxxxxx
Fixes: f09d160992d1 ("x86/entry/64: Get rid of the ALLOC_PT_GPREGS_ON_STACK and SAVE_AND_CLEAR_REGS macros")
Link: http://lkml.kernel.org/r/20180212174503.5acbymg5z6p32snu@treble
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/entry/entry_64.S | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1128,6 +1128,7 @@ idtentry machine_check do_mce has_err
* 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