[PATCH 04/11] powerpc/64: Convert the syscall exit path to use RFI_TO_USER/KERNEL
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2018-01-08 16:55:48
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
From: Nicholas Piggin <npiggin@gmail.com> 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@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> --- arch/powerpc/kernel/entry_64.S | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 567d8f487f2f..b20c6cb0fa7f 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S@@ -267,13 +267,23 @@ BEGIN_FTR_SECTION END_FTR_SECTION_IFSET(CPU_FTR_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 */ .Lsyscall_error:
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2.14.3