| Date | Thu, 21 May 2020 22:05:30 +0200 | From | Thomas Gleixner <> | Subject | [patch V9 17/39] x86/entry: Change exit path of xen_failsafe_callback |
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From: Thomas Gleixner <tglx@linutronix.de>
xen_failsafe_callback is invoked from XEN for two cases:
1. Fault while reloading DS, ES, FS or GS 2. Fault while executing IRET
#1 retries the IRET after XEN has fixed up the segments. #2 injects a #GP which kills the task
For #1 there is no reason to go through the full exception return path because the tasks TIF state is still the same. So just going straight to the IRET path is good enough.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Andy Lutomirski <luto@kernel.org> --- arch/x86/entry/entry_32.S | 2 +- arch/x86/entry/entry_64.S | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
--- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -1352,7 +1352,7 @@ SYM_FUNC_START(xen_failsafe_callback) 5: pushl $-1 /* orig_ax = -1 => not a system call */ SAVE_ALL ENCODE_FRAME_POINTER - jmp ret_from_exception + jmp handle_exception_return .section .fixup, "ax" 6: xorl %eax, %eax --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -1175,7 +1175,7 @@ SYM_CODE_START(xen_failsafe_callback) pushq $-1 /* orig_ax = -1 => not a system call */ PUSH_AND_CLEAR_REGS ENCODE_FRAME_POINTER - jmp error_exit + jmp error_return SYM_CODE_END(xen_failsafe_callback) #endif /* CONFIG_XEN_PV */
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