Patchwork [4/4] powerpc: No need to preserve count register across system call

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Submitter Anton Blanchard
Date April 5, 2012, 4:26 a.m.
Message ID <20120405142639.237dde63@kryten>
Download mbox | patch
Permalink /patch/150859/
State Accepted, archived
Delegated to: Benjamin Herrenschmidt
Headers show

Comments

Anton Blanchard - April 5, 2012, 4:26 a.m.
The count register is volatile so we don't need to preserve it.
Store zero to the entry in the exception frame.

Signed-off-by: Anton Blanchard <anton@samba.org>
---

Patch

Index: linux-build/arch/powerpc/kernel/entry_64.S
===================================================================
--- linux-build.orig/arch/powerpc/kernel/entry_64.S	2012-03-22 22:47:15.023504471 +1100
+++ linux-build/arch/powerpc/kernel/entry_64.S	2012-03-22 22:47:17.899556262 +1100
@@ -77,6 +77,7 @@  system_call_common:
 	std	r11,GPR11(r1)
 	std	r11,GPR12(r1)
 	std	r11,_XER(r1)
+	std	r11,_CTR(r1)
 	std	r9,GPR13(r1)
 	mflr	r10
 	li	r11,0xc01
@@ -87,8 +88,6 @@  system_call_common:
 	rlwinm	r2,r2,0,4,2
 	std	r10,_LINK(r1)
 	std	r11,_TRAP(r1)
-	mfctr	r10
-	std	r10,_CTR(r1)
 	std	r3,ORIG_GPR3(r1)
 	std	r2,_CCR(r1)
 	ld	r2,PACATOC(r13)