[Xen-changelog] Simplify the failsafe callback handler in x86/64 linux. It doesn't

[Xen patchbot -unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID 47dda4fa5d11c9bf66c3029fdd9be3cad0099ce9
# Parent  272a0a971ca3ed650fc3a74758f6862b3883bf9b
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@xxxxxxxxxxxxx>

diff -r 272a0a971ca3 -r 47dda4fa5d11 
linux-2.6-xen-sparse/arch/x86_64/kernel/entry-xen.S
--- a/linux-2.6-xen-sparse/arch/x86_64/kernel/entry-xen.S       Tue Mar 28 
08:57:48 2006
+++ b/linux-2.6-xen-sparse/arch/x86_64/kernel/entry-xen.S       Tue Mar 28 
09:01:35 2006
@@ -855,32 +855,12 @@
 # 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"

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog