Simplify the failsafe callback handler in x86/64 linux. It doesn't

need to try reloading segment selectors (unlike i386 linux).

Signed-off-by: Keir Fraser <keir@xensource.com>

diff --git a/linux-2.6-xen-sparse/arch/x86_64/kernel/entry-xen.S b/linux-2.6-xen-sparse/arch/x86_64/kernel/entry-xen.S
index 6f797e457df0bd0f8c6f9c1a8b293ea74d400591..08b5f53f6af7808e793fa449f7edfedbb0086f14 100644 (file)
--- a/linux-2.6-xen-sparse/arch/x86_64/kernel/entry-xen.S
+++ b/linux-2.6-xen-sparse/arch/x86_64/kernel/entry-xen.S
@@ -855,32 +855,12 @@ ecrit:  /**** END OF CRITICAL REGION ****/
 # i.e. it just resumes from the next instruction interrupted with the same context. 
        
 # Hypervisor uses this for application faults while it executes.
+# Unlike i386 there is no need to reload the saved segment selectors:
+# Xen already reloaded all valid ones and zeroed the others.
 ENTRY(failsafe_callback)
-       addq $0x10,%rsp /* skip rcx and r11 */  
-1:     mov  (%rsp),%ds
-2:     mov  8(%rsp),%es
-3:     mov  16(%rsp),%fs
-4:     mov  24(%rsp),%gs
-       addq $0x20,%rsp /* skip the above selectors */          
+       addq $0x30,%rsp /* skip %rcx,%r11,%ds,%es,%fs,%gs */
        SAVE_ALL
        jmp  error_exit
-.section .fixup,"ax";  \
-6:     movq $0,(%rsp); \
-       jmp 1b;         \
-7:     movq $0,8(%rsp);        \
-       jmp 2b;         \
-8:     movq $0,16(%rsp);       \
-       jmp 3b;         \
-9:     movq $0,24(%rsp);       \
-       jmp 4b;         \
-.previous;             \
-.section __ex_table,"a";\
-       .align 16;      \
-       .quad 1b,6b;    \
-       .quad 2b,7b;    \
-       .quad 3b,8b;    \
-       .quad 4b,9b;    \
-.previous
  
 #if 0        
         .section __ex_table,"a"