linux-kernel - [PATCH v2] microblaze: nommu: Don't clobber R11 on syscalls

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Message-Id: <1260829458-7503-1-git-send-email-steve@digidescorp.com>
Date:	Mon, 14 Dec 2009 16:24:18 -0600
From:	steve@...idescorp.com
To:	microblaze-uclinux@...e.uq.edu.au
Cc:	monstr@...str.eu, linux-kernel@...r.kernel.org,
	"Steven J. Magnani" <steve@...idescorp.com>
Subject: [PATCH v2] microblaze: nommu: Don't clobber R11 on syscalls

The noMMU syscall trap has a bug that causes R11 to be zero on return to 
userland. Remove the extra "save" of R11 responsible for the bug, as well
as an unnecessary extra "load".

Signed-off-by: Steven J. Magnani <steve@...idescorp.com>
---
diff -uprN a/arch/microblaze/kernel/entry-nommu.S b/arch/microblaze/kernel/entry-nommu.S
--- a/arch/microblaze/kernel/entry-nommu.S	2009-12-09 17:05:11.000000000 -0600
+++ b/arch/microblaze/kernel/entry-nommu.S	2009-12-14 11:29:37.000000000 -0600
@@ -208,8 +208,6 @@ ENTRY(_user_exception)
 	lwi	r1, r1, TS_THREAD_INFO		/* get the thread info */
 	/* calculate kernel stack pointer */
 	addik	r1, r1, THREAD_SIZE - PT_SIZE
-	swi	r11, r0, PER_CPU(R11_SAVE)	/* temporarily save r11 */
-	lwi	r11, r0, PER_CPU(KM)		/* load mode indicator */
 2:
 	swi	r11, r1, PT_MODE		/* store the mode */
 	lwi	r11, r0, PER_CPU(R11_SAVE)	/* reload r11 */

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