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Diffstat (limited to 'arch/powerpc/kernel/exceptions-64s.S')
-rw-r--r--arch/powerpc/kernel/exceptions-64s.S24
1 files changed, 23 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 48da0f5d2f7f..b82586c53560 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -734,7 +734,29 @@ EXC_REAL(program_check, 0x700, 0x100)
EXC_VIRT(program_check, 0x4700, 0x100, 0x700)
TRAMP_KVM(PACA_EXGEN, 0x700)
EXC_COMMON_BEGIN(program_check_common)
- EXCEPTION_PROLOG_COMMON(0x700, PACA_EXGEN)
+ /*
+ * It's possible to receive a TM Bad Thing type program check with
+ * userspace register values (in particular r1), but with SRR1 reporting
+ * that we came from the kernel. Normally that would confuse the bad
+ * stack logic, and we would report a bad kernel stack pointer. Instead
+ * we switch to the emergency stack if we're taking a TM Bad Thing from
+ * the kernel.
+ */
+ li r10,MSR_PR /* Build a mask of MSR_PR .. */
+ oris r10,r10,0x200000@h /* .. and SRR1_PROGTM */
+ and r10,r10,r12 /* Mask SRR1 with that. */
+ srdi r10,r10,8 /* Shift it so we can compare */
+ cmpldi r10,(0x200000 >> 8) /* .. with an immediate. */
+ bne 1f /* If != go to normal path. */
+
+ /* SRR1 had PR=0 and SRR1_PROGTM=1, so use the emergency stack */
+ andi. r10,r12,MSR_PR; /* Set CR0 correctly for label */
+ /* 3 in EXCEPTION_PROLOG_COMMON */
+ mr r10,r1 /* Save r1 */
+ ld r1,PACAEMERGSP(r13) /* Use emergency stack */
+ subi r1,r1,INT_FRAME_SIZE /* alloc stack frame */
+ b 3f /* Jump into the macro !! */
+1: EXCEPTION_PROLOG_COMMON(0x700, PACA_EXGEN)
bl save_nvgprs
RECONCILE_IRQ_STATE(r10, r11)
addi r3,r1,STACK_FRAME_OVERHEAD