This is a note to let you know that I've just added the patch titled
powerpc/64: Convert the syscall exit path to use RFI_TO_USER/KERNEL
to the 4.4-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-the-syscall-exit-path-to-use-rfi_to_user-kernel.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b8e90cb7bc04a509e821e82ab6ed7a8ef11ba333 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 the syscall exit path to use RFI_TO_USER/KERNEL
From: Nicholas Piggin <npiggin@xxxxxxxxx>
commit b8e90cb7bc04a509e821e82ab6ed7a8ef11ba333 upstream.
In the syscall exit path 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 | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -230,13 +230,23 @@ END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECK
ACCOUNT_CPU_USER_EXIT(r11, r12)
HMT_MEDIUM_LOW_HAS_PPR
ld r13,GPR13(r1) /* only restore r13 if returning to usermode */
+ ld r2,GPR2(r1)
+ ld r1,GPR1(r1)
+ mtlr r4
+ mtcr r5
+ mtspr SPRN_SRR0,r7
+ mtspr SPRN_SRR1,r8
+ RFI_TO_USER
+ b . /* prevent speculative execution */
+
+ /* exit to kernel */
1: ld r2,GPR2(r1)
ld r1,GPR1(r1)
mtlr r4
mtcr r5
mtspr SPRN_SRR0,r7
mtspr SPRN_SRR1,r8
- RFI
+ RFI_TO_KERNEL
b . /* prevent speculative execution */
syscall_error:
Patches currently in stable-queue which might be from npiggin@xxxxxxxxx are
queue-4.4/powerpc-64s-simple-rfi-macro-conversions.patch
queue-4.4/powerpc-64-add-macros-for-annotating-the-destination-of-rfid-hrfid.patch
queue-4.4/powerpc-64s-allow-control-of-rfi-flush-via-debugfs.patch
queue-4.4/powerpc-64s-convert-slb_miss_common-to-use-rfi_to_user-kernel.patch
queue-4.4/powerpc-64-convert-the-syscall-exit-path-to-use-rfi_to_user-kernel.patch
queue-4.4/powerpc-64s-add-support-for-rfi-flush-of-l1-d-cache.patch
queue-4.4/powerpc-64-convert-fast_exception_return-to-use-rfi_to_user-kernel.patch