Re: [PATCH 1/2] x86/entry/64: Do not clear %rbx under Xen

On 07/21/2018 03:49 PM, M. Vefa Bicakci wrote:

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index c7449f377a77..96e8ff34129e 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -1129,7 +1129,7 @@ ENTRY(xen_failsafe_callback) addq $0x30, %rsp UNWIND_HINT_IRET_REGS pushq $-1 /* orig_ax = -1 => not a system call */

• PUSH_AND_CLEAR_REGS

• PUSH_AND_CLEAR_REGS clear_rbx=0

Do we need this at all? We are returning from the hypervisor here.

-boris

ENCODE_FRAME_POINTER jmp error_exit END(xen_failsafe_callback)