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Date: Thu, 10 Oct 2019 10:34:45 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
Doug Crawford <doug.crawford@...elight-its.com>,
Christophe Leroy <christophe.leroy@....fr>,
Michael Ellerman <mpe@...erman.id.au>
Subject: [PATCH 5.3 024/148] powerpc/603: Fix handling of the DIRTY flag
From: Christophe Leroy <christophe.leroy@....fr>
commit 415480dce2ef03bb8335deebd2f402f475443ce0 upstream.
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: f8b58c64eaef ("powerpc/603: let's handle PAGE_DIRTY directly")
Cc: stable@...r.kernel.org # v5.1+
Reported-by: Doug Crawford <doug.crawford@...elight-its.com>
Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Link: https://lore.kernel.org/r/80432f71194d7ee75b2f5043ecf1501cf1cca1f3.1566196646.git.christophe.leroy@c-s.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
arch/powerpc/kernel/head_32.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -557,9 +557,9 @@ DataStoreTLBMiss:
cmplw 0,r1,r3
mfspr r2, SPRN_SPRG_PGDIR
#ifdef CONFIG_SWAP
- li r1, _PAGE_RW | _PAGE_PRESENT | _PAGE_ACCESSED
+ li r1, _PAGE_RW | _PAGE_DIRTY | _PAGE_PRESENT | _PAGE_ACCESSED
#else
- li r1, _PAGE_RW | _PAGE_PRESENT
+ li r1, _PAGE_RW | _PAGE_DIRTY | _PAGE_PRESENT
#endif
bge- 112f
lis r2, (swapper_pg_dir - PAGE_OFFSET)@ha /* if kernel address, use */
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