[PATCH 5.5 051/150] powerpc/8xx: Fix clearing of bits 20-23 in ITLB miss
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2020-02-27 14:14:47
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From: Christophe Leroy <redacted>
commit a4031afb9d10d97f4d0285844abbc0ab04245304 upstream.
In ITLB miss handled the line supposed to clear bits 20-23 on the L2
ITLB entry is buggy and does indeed nothing, leading to undefined
value which could allow execution when it shouldn't.
Properly do the clearing with the relevant instruction.
Fixes: 74fabcadfd43 ("powerpc/8xx: don't use r12/SPRN_SPRG_SCRATCH2 in TLB Miss handlers")
Cc: stable@vger.kernel.org # v5.0+
Signed-off-by: Christophe Leroy <redacted>
Reviewed-by: Leonardo Bras <redacted>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/4f70c2778163affce8508a210f65d140e84524b4.1581272050.git.christophe.leroy@c-s.fr (local)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/powerpc/kernel/head_8xx.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S@@ -289,7 +289,7 @@ InstructionTLBMiss: * set. All other Linux PTE bits control the behavior * of the MMU. */ - rlwimi r10, r10, 0, 0x0f00 /* Clear bits 20-23 */ + rlwinm r10, r10, 0, ~0x0f00 /* Clear bits 20-23 */ rlwimi r10, r10, 4, 0x0400 /* Copy _PAGE_EXEC into bit 21 */ ori r10, r10, RPN_PATTERN | 0x200 /* Set 22 and 24-27 */ mtspr SPRN_MI_RPN, r10 /* Update TLB entry */