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powerpc/mm: add exec protection on powerpc 603

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The 603 doesn't have a HASH table, TLB misses are handled by
software. It is then possible to generate page fault when
_PAGE_EXEC is not set like in nohash/32.

There is one "reserved" PTE bit available, this patch uses
it for _PAGE_EXEC.

In order to support it, set_pte_filter() and
set_access_flags_filter() are made common, and the handling
is made dependent on MMU_FTR_HPTE_TABLE

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Christophe Leroy
2018-12-19 18:56:32 +11:00
committed by Michael Ellerman
parent badb9687ce
commit 385e89d5b2
6 changed files with 26 additions and 25 deletions
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arch/powerpc/kernel/head_32.S
+1 -1
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@@ -503,7 +503,7 @@ InstructionTLBMiss:
lis r1,PAGE_OFFSET@h /* check if kernel address */
cmplw 0,r1,r3
mfspr r2,SPRN_SPRG_THREAD
li r1,_PAGE_USER|_PAGE_PRESENT /* low addresses tested as user */
li r1,_PAGE_USER|_PAGE_PRESENT|_PAGE_EXEC /* low addresses tested as user */
lwz r2,PGDIR(r2)
bge- 112f
mfspr r2,SPRN_SRR1 /* and MSR_PR bit from SRR1 */