diff options
authorNicholas Piggin <>2019-06-22 08:55:54 +1000
committerMichael Ellerman <>2019-06-25 21:04:27 +1000
commite13e7cd4c0c1cc9984d9b6a8663e10d76b53f2aa (patch)
parent50087112592016a3fc10b394a55f1f1a1bde6908 (diff)
powerpc/64s/exception: Fix machine check early corrupting AMR
The early machine check runs in real mode, so locking is unnecessary. Worse, the windup does not restore AMR, so this can result in a false KUAP fault after a recoverable machine check hits inside a user copy operation. Fix this similarly to HMI by just avoiding the kuap lock in the early machine check handler (it will be set by the late handler that runs in virtual mode if that runs). If the virtual mode handler is reached, it will lock and restore the AMR. Fixes: 890274c2dc4c0 ("powerpc/64s: Implement KUAP for Radix MMU") Cc: Russell Currey <> Signed-off-by: Nicholas Piggin <> Signed-off-by: Michael Ellerman <>
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 6b86055e5251..73ba246ca11d 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -315,7 +315,7 @@ TRAMP_REAL_BEGIN(machine_check_common_early)
mfspr r11,SPRN_DSISR /* Save DSISR */
std r11,_DSISR(r1)
std r9,_CCR(r1) /* Save CR in stackframe */
- kuap_save_amr_and_lock r9, r10, cr1
+ /* We don't touch AMR here, we never go to virtual mode */
/* Save r9 through r13 from EXMC save area to stack frame. */
mfmsr r11 /* get MSR value */