The SLB bad address handler's trap number fixup does not preserve the
low bit that indicates nonvolatile GPRs have not been saved. This
leads save_nvgprs to skip saving them, and subsequent functions and
return from interrupt will think they are saved.
This causes kernel branch-to-garbage debugging to not have correct
registers, can also cause userspace to have its registers clobbered
after a segfault.
Fixes: f0f558b131 ("powerpc/mm: Preserve CFAR value on SLB miss caused by
access to bogus address")
Cc: Paul Mackerras <pau...@ozlabs.org>
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/kernel/exceptions-64s.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S
b/arch/powerpc/kernel/exceptions-64s.S
index 3ac87e53b3da..1ecfd8ffb098 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -706,7 +706,7 @@ EXC_COMMON_BEGIN(bad_addr_slb)
ld r3, PACA_EXSLB+EX_DAR(r13)
std r3, _DAR(r1)
beq cr6, 2f
- li r10, 0x480 /* fix trap number for I-SLB miss */
+ li r10, 0x481 /* fix trap number for I-SLB miss */
std r10, _TRAP(r1)
2: bl save_nvgprs
addi r3, r1, STACK_FRAME_OVERHEAD
--
2.16.1
