From: Nicholas Piggin <npig...@gmail.com>
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 <npig...@gmail.com>
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
[mpe: Backport to 4.4 based on patch from Balbir]
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
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
