x86/entry: Change exit path of xen_failsafe_callback

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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20200521202118.423224507@linutronix.de

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 6c6ae3a..6fcdee9 100644 (file)
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -1355,7 +1355,7 @@ 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

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 2e476f4..a526fb5 100644 (file)
--- 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 */