Patch "powerpc/tm: do not use r13 for tabort_syscall" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

powerpc/tm: do not use r13 for tabort_syscall

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
powerpc-tm-do-not-use-r13-for-tabort_syscall.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Nicholas Piggin <[email protected]>
Date: Mon, 25 Jul 2016 14:26:51 +1000
Subject: powerpc/tm: do not use r13 for tabort_syscall

From: Nicholas Piggin <[email protected]>

commit cc7786d3ee7e3c979799db834b528db2c0834c2e upstream.

tabort_syscall runs with RI=1, so a nested recoverable machine check will load the paca into r13 and overwrite what we loaded it with, because exceptions returning to privileged mode do not restore r13.

---
 arch/powerpc/kernel/entry_64.S |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

@@ -368,13 +368,13 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 tabort_syscall:
 	/* Firstly we need to enable TM in the kernel */
 	mfmsr	r10
-	li	r13, 1
-	rldimi	r10, r13, MSR_TM_LG, 63-MSR_TM_LG
+	li	r9, 1
+	rldimi	r10, r9, MSR_TM_LG, 63-MSR_TM_LG
 	mtmsrd	r10, 0
 
 	/* tabort, this dooms the transaction, nothing else */
-	li	r13, (TM_CAUSE_SYSCALL|TM_CAUSE_PERSISTENT)
-	TABORT(R13)
+	li	r9, (TM_CAUSE_SYSCALL|TM_CAUSE_PERSISTENT)
+	TABORT(R9)
 
 	/*
 	 * Return directly to userspace. We have corrupted user register state,

@@ -382,8 +382,8 @@ tabort_syscall:
 	 * resume after the tbegin of the aborted transaction with the
 	 * checkpointed register state.
 	 */
-	li	r13, MSR_RI
-	andc	r10, r10, r13
+	li	r9, MSR_RI
+	andc	r10, r10, r9
 	mtmsrd	r10, 1
 	mtspr	SPRN_SRR0, r11
 	mtspr	SPRN_SRR1, r12

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/powerpc-tm-do-not-use-r13-for-tabort_syscall.patch queue-4.7/sched-core-fix-a-race-between-try_to_wake_up-and-a-woken-up-task.patch