| Submitter | Anton Blanchard |
|---|---|
| Date | April 5, 2012, 4:24 a.m. |
| Message ID | <20120405142429.7bb7785c@kryten> |
| Download | mbox | patch |
| Permalink | /patch/150857/ |
| State | Accepted |
| Commit | 823df43552da39fd48a2dd74949363a1c8cf62bb |
| Delegated to: | Benjamin Herrenschmidt |
| Headers | show |
Comments
Patch
Index: linux-build/arch/powerpc/kernel/entry_64.S =================================================================== --- linux-build.orig/arch/powerpc/kernel/entry_64.S 2012-03-22 22:47:04.479314599 +1100 +++ linux-build/arch/powerpc/kernel/entry_64.S 2012-03-22 22:47:08.379384827 +1100 @@ -82,6 +82,7 @@ system_call_common: std r11,GPR10(r1) std r11,GPR11(r1) std r11,GPR12(r1) + std r11,_XER(r1) std r9,GPR13(r1) mfcr r9 mflr r10 @@ -89,9 +90,7 @@ system_call_common: std r9,_CCR(r1) std r10,_LINK(r1) std r11,_TRAP(r1) - mfxer r9 mfctr r10 - std r9,_XER(r1) std r10,_CTR(r1) std r3,ORIG_GPR3(r1) ld r2,PACATOC(r13)
The XER is a volatile register so there is no need to save and restore it over a system call - zero it out in the exception stack frame instead. This should fix a 5 cycle stall of the mfxer/std seen on POWER7. Signed-off-by: Anton Blanchard <anton@samba.org> ---