From: Nicholas Piggin <npiggin@xxxxxxxxx> commit c7305645eb0c1621351cfc104038831ae87c0053 upstream. In the SLB miss handler we may be returning to user or kernel. We need to add a check early on and save the result in the cr4 register, and then we bifurcate the return path based on that. Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx> [mpe: Backport to 4.4 based on patch from Balbir] Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/powerpc/kernel/exceptions-64s.S | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 591efc03f80d..c7dfd67c14da 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -1511,6 +1511,8 @@ slb_miss_realmode: andi. r10,r12,MSR_RI /* check for unrecoverable exception */ beq- 2f + andi. r10,r12,MSR_PR /* check for user mode (PR != 0) */ + bne 1f .machine push .machine "power4" @@ -1524,7 +1526,23 @@ slb_miss_realmode: ld r11,PACA_EXSLB+EX_R11(r13) ld r12,PACA_EXSLB+EX_R12(r13) ld r13,PACA_EXSLB+EX_R13(r13) - rfid + RFI_TO_KERNEL + b . /* prevent speculative execution */ + +1: +.machine push +.machine "power4" + mtcrf 0x80,r9 + mtcrf 0x01,r9 /* slb_allocate uses cr0 and cr7 */ +.machine pop + + RESTORE_PPR_PACA(PACA_EXSLB, r9) + ld r9,PACA_EXSLB+EX_R9(r13) + ld r10,PACA_EXSLB+EX_R10(r13) + ld r11,PACA_EXSLB+EX_R11(r13) + ld r12,PACA_EXSLB+EX_R12(r13) + ld r13,PACA_EXSLB+EX_R13(r13) + RFI_TO_USER b . /* prevent speculative execution */ 2: mfspr r11,SPRN_SRR0 @@ -1533,7 +1551,7 @@ slb_miss_realmode: mtspr SPRN_SRR0,r10 ld r10,PACAKMSR(r13) mtspr SPRN_SRR1,r10 - rfid + RFI_TO_KERNEL b . unrecov_slb: -- 2.14.1