Commit 00e40620 authored Jan 10, 2018 by Nicholas Piggin Committed by Greg Kroah-Hartman Feb 13, 2018

powerpc/64: Convert the syscall exit path to use RFI_TO_USER/KERNEL



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@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 9d914324

arch/powerpc/kernel/entry_64.S

+11 −1

Original line number	Diff line number	Diff line
		@@ -251,13 +251,23 @@ 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 */

		syscall_error: