[PATCH 4.14 16/67] powerpc/64s: Fix i-side SLB miss bad address handler saving nonvolatile GPRs

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

--

From: Nicholas Piggin 

commit 52396500f97c53860164debc7d4f759077853423 upstream.

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: f0f558b131db ("powerpc/mm: Preserve CFAR value on SLB miss caused by 
access to bogus address")
Cc: sta...@vger.kernel.org # v4.9+
Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman 

---
 arch/powerpc/kernel/exceptions-64s.S |2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -704,7 +704,7 @@ 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
addir3, r1, STACK_FRAME_OVERHEAD

[PATCH 4.14 16/67] powerpc/64s: Fix i-side SLB miss bad address handler saving nonvolatile GPRs

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

--

From: Nicholas Piggin 

commit 52396500f97c53860164debc7d4f759077853423 upstream.

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: f0f558b131db ("powerpc/mm: Preserve CFAR value on SLB miss caused by 
access to bogus address")
Cc: sta...@vger.kernel.org # v4.9+
Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman 

---
 arch/powerpc/kernel/exceptions-64s.S |2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -704,7 +704,7 @@ 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
addir3, r1, STACK_FRAME_OVERHEAD