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powerpc/603: Fix handling of the DIRTY flag 

If a page is already mapped RW without the DIRTY flag, the DIRTY
flag is never set and a TLB store miss exception is taken forever.

This is easily reproduced with the following app:

void main(void)
{
	volatile char *ptr = mmap(0, 4096, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);

	*ptr = *ptr;
}

When DIRTY flag is not set, bail out of TLB miss handler and take
a minor page fault which will set the DIRTY flag.

Fixes: f8b58c64ea ("powerpc/603: let's handle PAGE_DIRTY directly")
Cc: stable@vger.kernel.org # v5.1+
Reported-by: Doug Crawford <doug.crawford@intelight-its.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/80432f71194d7ee75b2f5043ecf1501cf1cca1f3.1566196646.git.christophe.leroy@c-s.fr
This commit is contained in:
Christophe Leroy 2019-08-19 06:40:25 +00:00 committed by Michael Ellerman
parent 6bb25170d7
commit 415480dce2
1 changed files with 2 additions and 2 deletions
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4
arch/powerpc/kernel/head_32.S
View File

@ -557,9 +557,9 @@ DataStoreTLBMiss:
cmplw 0,r1,r3 cmplw 0,r1,r3
mfspr r2, SPRN_SPRG_PGDIR mfspr r2, SPRN_SPRG_PGDIR
#ifdef CONFIG_SWAP #ifdef CONFIG_SWAP
li r1, _PAGE_RW | _PAGE_PRESENT | _PAGE_ACCESSED li r1, _PAGE_RW | _PAGE_DIRTY | _PAGE_PRESENT | _PAGE_ACCESSED
#else #else
li r1, _PAGE_RW | _PAGE_PRESENT li r1, _PAGE_RW | _PAGE_DIRTY | _PAGE_PRESENT
#endif #endif
bge- 112f bge- 112f
lis r2, (swapper_pg_dir - PAGE_OFFSET)@ha /* if kernel address, use */ lis r2, (swapper_pg_dir - PAGE_OFFSET)@ha /* if kernel address, use */