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 <stable@xxxxxxxxxxxxxxx> know about it. >From a08f828cf47e6c605af21d2cdec68f84e799c318 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin <npiggin@xxxxxxxxx> 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 <npiggin@xxxxxxxxx> 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. Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/powerpc/kernel/entry_64.S | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -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 npiggin@xxxxxxxxx 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