In message: [linux-yocto][PATCH] powerpc/603: Fix handling of the DIRTY flag
on 24/09/2019 zhe...@windriver.com wrote:
> From: Christophe Leroy
>
> 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: sta...@vger.kernel.org # v5.1+
> Reported-by: Doug Crawford
> Signed-off-by: Christophe Leroy
> Signed-off-by: Michael Ellerman
> Link:
> https://lore.kernel.org/r/80432f71194d7ee75b2f5043ecf1501cf1cca1f3.1566196646.git.christophe.le...@c-s.fr
> Signed-off-by: He Zhe
> ---
> This is for v5.2/standard/fsl-mpc8315e-rdb. It fixes potential system hang
> without any direct warning or error which has not been observed on qemuppc.
>
> It has not been ported to stable tree.
but at least is has been cc'd to stable. I'll watch for it to show up in my
future 5.2 -stabe updates.
Cheers,
Bruce
>
> arch/powerpc/kernel/head_32.S | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
> index f255e22..534dd27 100644
> --- 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 */
> --
> 2.7.4
>
--
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