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powerpc/64s: Convert slb_miss_common to use RFI_TO_USER/KERNEL 

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@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2018-01-10 03:07:15 +11:00 committed by Michael Ellerman
parent a08f828cf4
commit c7305645eb
1 changed files with 28 additions and 1 deletions
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29
arch/powerpc/kernel/exceptions-64s.S
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@ -598,6 +598,9 @@ EXC_COMMON_BEGIN(slb_miss_common)
stw r9,PACA_EXSLB+EX_CCR(r13) /* save CR in exc. frame */
std r10,PACA_EXSLB+EX_LR(r13) /* save LR */
andi. r9,r11,MSR_PR // Check for exception from userspace
cmpdi cr4,r9,MSR_PR // And save the result in CR4 for later
/*
* Test MSR_RI before calling slb_allocate_realmode, because the
* MSR in r11 gets clobbered. However we still want to allocate
@ -624,9 +627,12 @@ END_MMU_FTR_SECTION_IFCLR(MMU_FTR_TYPE_RADIX)
/* All done -- return from exception. */
bne cr4,1f /* returning to kernel */
.machine push
.machine "power4"
mtcrf 0x80,r9
mtcrf 0x08,r9 /* MSR[PR] indication is in cr4 */
mtcrf 0x04,r9 /* MSR[RI] indication is in cr5 */
mtcrf 0x02,r9 /* I/D indication is in cr6 */
mtcrf 0x01,r9 /* slb_allocate uses cr0 and cr7 */
@ -640,8 +646,29 @@ END_MMU_FTR_SECTION_IFCLR(MMU_FTR_TYPE_RADIX)
ld r11,PACA_EXSLB+EX_R11(r13)
ld r12,PACA_EXSLB+EX_R12(r13)
ld r13,PACA_EXSLB+EX_R13(r13)
rfid
RFI_TO_USER
b . /* prevent speculative execution */
1:
.machine push
.machine "power4"
mtcrf 0x80,r9
mtcrf 0x08,r9 /* MSR[PR] indication is in cr4 */
mtcrf 0x04,r9 /* MSR[RI] indication is in cr5 */
mtcrf 0x02,r9 /* I/D indication is in cr6 */
mtcrf 0x01,r9 /* slb_allocate uses cr0 and cr7 */
.machine pop
RESTORE_CTR(r9, PACA_EXSLB)
RESTORE_PPR_PACA(PACA_EXSLB, r9)
mr r3,r12
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_KERNEL
b . /* prevent speculative execution */
2: std r3,PACA_EXSLB+EX_DAR(r13)
mr r3,r12