[PATCH] powerpc: set stack limit properly in crit_transfer_to_handler

[Stuart Yoder]

From: Stuart Yoder <stuart.yoder at freescale.com>

without setting the stack limit like this there is the possibility
of stack overflow which corrupts the thread info but
is not detected by stack overflow detection

Signed-off-by: Stuart Yoder <stuart.yoder at freescale.com>
---
 arch/powerpc/kernel/entry_32.S |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 5207d5a..ead5016 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -89,10 +89,14 @@ crit_transfer_to_handler:
 	mfspr	r0,SPRN_SRR1
 	stw	r0,_SRR1(r11)
 
+	/* set the stack limit to the current stack
+	 * and set the limit to protect the thread_info
+	 * struct
+	 */
 	mfspr	r8,SPRN_SPRG_THREAD
 	lwz	r0,KSP_LIMIT(r8)
 	stw	r0,SAVED_KSP_LIMIT(r11)
-	CURRENT_THREAD_INFO(r0, r1)
+	rlwimi	r0,r1,0,0,(31-THREAD_SHIFT)
 	stw	r0,KSP_LIMIT(r8)
 	/* fall through */
 #endif
@@ -109,10 +113,14 @@ crit_transfer_to_handler:
 	mfspr	r0,SPRN_SRR1
 	stw	r0,crit_srr1 at l(0)
 
+	/* set the stack limit to the current stack
+	 * and set the limit to protect the thread_info
+	 * struct
+	 */
 	mfspr	r8,SPRN_SPRG_THREAD
 	lwz	r0,KSP_LIMIT(r8)
 	stw	r0,saved_ksp_limit at l(0)
-	CURRENT_THREAD_INFO(r0, r1)
+	rlwimi	r0,r1,0,0,(31-THREAD_SHIFT)
 	stw	r0,KSP_LIMIT(r8)
 	/* fall through */
 #endif
-- 
1.7.3.4