Commit 52396500 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman

powerpc/64s: Fix i-side SLB miss bad address handler saving nonvolatile GPRs

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: f0f558b1 ("powerpc/mm: Preserve CFAR value on SLB miss caused by access to bogus address")
Cc: stable@vger.kernel.org # v4.9+
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent a5d4b589
...@@ -706,7 +706,7 @@ EXC_COMMON_BEGIN(bad_addr_slb) ...@@ -706,7 +706,7 @@ EXC_COMMON_BEGIN(bad_addr_slb)
ld r3, PACA_EXSLB+EX_DAR(r13) ld r3, PACA_EXSLB+EX_DAR(r13)
std r3, _DAR(r1) std r3, _DAR(r1)
beq cr6, 2f 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) std r10, _TRAP(r1)
2: bl save_nvgprs 2: bl save_nvgprs
addi r3, r1, STACK_FRAME_OVERHEAD addi r3, r1, STACK_FRAME_OVERHEAD
......
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