4.4-stable review patch. If anyone has any objections, please let me know.
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From: Nicholas Piggin npiggin@gmail.com
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
--- 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: