[PATCH AUTOSEL 4.14 134/170] powerpc/mm: Fix reporting of kernel execute faults on the 8xx

[Sasha Levin <sashal@kernel.org>]

From: Christophe Leroy <christophe.leroy@c-s.fr>

[ Upstream commit ffca395b11c4a5a6df6d6345f794b0e3d578e2d0 ]

On the 8xx, no-execute is set via PPP bits in the PTE. Therefore
a no-exec fault generates DSISR_PROTFAULT error bits,
not DSISR_NOEXEC_OR_G.

This patch adds DSISR_PROTFAULT in the test mask.

Fixes: d3ca587404b3 ("powerpc/mm: Fix reporting of kernel execute faults")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/powerpc/mm/fault.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 6e1e39035380..52863deed65d 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -215,7 +215,9 @@ static int mm_fault_error(struct pt_regs *regs, unsigned long addr, int fault)
 static bool bad_kernel_fault(bool is_exec, unsigned long error_code,
 			     unsigned long address)
 {
-	if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT))) {
+	/* NX faults set DSISR_PROTFAULT on the 8xx, DSISR_NOEXEC_OR_G on others */
+	if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT |
+				      DSISR_PROTFAULT))) {
 		printk_ratelimited(KERN_CRIT "kernel tried to execute"
 				   " exec-protected page (%lx) -"
 				   "exploit attempt? (uid: %d)\n",
-- 
2.19.1