Patch "powerpc/64: Convert the syscall exit path to use RFI_TO_USER/KERNEL" has been added to the 4.4-stable tree
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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 <[email protected]> know about it.
Quoted 1 line
From
b8e90cb7bc04a509e821e82ab6ed7a8ef11ba333Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <[email protected]>
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 <[email protected]>
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.
--- arch/powerpc/kernel/entry_64.S | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
arch/powerpc/kernel/entry_64.S +11 -1
@@ -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 [email protected] 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