Patch "powerpc/64: Convert fast_exception_return to use RFI_TO_USER/KERNEL" has been added to the 4.9-stable tree

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

powerpc/64: Convert fast_exception_return to use RFI_TO_USER/KERNEL

to the 4.9-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-64-convert-fast_exception_return-to-use-rfi_to_user-kernel.patch
and it can be found in the queue-4.9 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: Wed, 10 Jan 2018 03:07:15 +1100
Subject: powerpc/64: Convert fast_exception_return to use RFI_TO_USER/KERNEL

From: Nicholas Piggin <[email protected]>

commit a08f828cf47e6c605af21d2cdec68f84e799c318 upstream.

Similar to the syscall return path, in fast_exception_return we may be returning to user or kernel context. We already have a test for that, because we conditionally restore r13. So use that existing test and branch, and bifurcate the return based on that.

---
 arch/powerpc/kernel/entry_64.S |   18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

@@ -859,7 +859,7 @@ BEGIN_FTR_SECTION
 END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 	ACCOUNT_CPU_USER_EXIT(r13, r2, r4)
 	REST_GPR(13, r1)
-1:
+
 	mtspr	SPRN_SRR1,r3
 
 	ld	r2,_CCR(r1)

@@ -872,8 +872,22 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 	ld	r3,GPR3(r1)
 	ld	r4,GPR4(r1)
 	ld	r1,GPR1(r1)
+	RFI_TO_USER
+	b	.	/* prevent speculative execution */
 
-	rfid
+1:	mtspr	SPRN_SRR1,r3
+
+	ld	r2,_CCR(r1)
+	mtcrf	0xFF,r2
+	ld	r2,_NIP(r1)
+	mtspr	SPRN_SRR0,r2
+
+	ld	r0,GPR0(r1)
+	ld	r2,GPR2(r1)
+	ld	r3,GPR3(r1)
+	ld	r4,GPR4(r1)
+	ld	r1,GPR1(r1)
+	RFI_TO_KERNEL
 	b	.	/* prevent speculative execution */
 
 #endif /* CONFIG_PPC_BOOK3E */

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

queue-4.9/powerpc-64-add-macros-for-annotating-the-destination-of-rfid-hrfid.patch queue-4.9/powerpc-64s-allow-control-of-rfi-flush-via-debugfs.patch queue-4.9/powerpc-64s-convert-slb_miss_common-to-use-rfi_to_user-kernel.patch queue-4.9/powerpc-64-convert-the-syscall-exit-path-to-use-rfi_to_user-kernel.patch queue-4.9/powerpc-64s-add-support-for-rfi-flush-of-l1-d-cache.patch queue-4.9/powerpc-64-convert-fast_exception_return-to-use-rfi_to_user-kernel.patch