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powerpc/64: Convert fast_exception_return to use RFI_TO_USER/KERNEL

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commit a08f828cf4 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@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nicholas Piggin
2018-01-10 03:07:15 +11:00
committed by Greg Kroah-Hartman
parent 7ca8316cb9
commit 9bfecafe84
1 changed files with 16 additions and 2 deletions
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18
arch/powerpc/kernel/entry_64.S
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@@ -891,7 +891,7 @@ BEGIN_FTR_SECTION
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
ACCOUNT_CPU_USER_EXIT(r2, r4)
REST_GPR(13, r1)
1:
mtspr SPRN_SRR1,r3
ld r2,_CCR(r1)
@@ -904,8 +904,22 @@ 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 */