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powerpc/8xx: Fix clearing of bits 20-23 in ITLB miss

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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 <christophe.leroy@c-s.fr>
Reviewed-by: Leonardo Bras <leonardo@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/4f70c2778163affce8508a210f65d140e84524b4.1581272050.git.christophe.leroy@c-s.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Christophe Leroy 2020-02-09 18:14:42 +00:00 committed by Greg Kroah-Hartman
parent 2558e71bbf
commit 9e1fab4450
1 changed files with 1 additions and 1 deletions
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2
arch/powerpc/kernel/head_8xx.S
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@ -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 */