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SubjectRe: [PATCH V2] riscv: Fixup race condition on PG_dcache_clean in flush_icache_pte
On Thu, Jan 26, 2023 at 10:53:06PM -0500, guoren@kernel.org wrote:
> From: Guo Ren <guoren@linux.alibaba.com>
>
> In commit 588a513d3425 ("arm64: Fix race condition on PG_dcache_clean
> in __sync_icache_dcache()"), we found RISC-V has the same issue as the
> previous arm64. The previous implementation didn't guarantee the correct
> sequence of operations, which means flush_icache_all() hasn't been
> called when the PG_dcache_clean was set. That would cause a risk of page
> synchronization.
>
> Fixes: 08f051eda33b ("RISC-V: Flush I$ when making a dirty page executable")
> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> Signed-off-by: Guo Ren <guoren@kernel.org>
> ---
> Changelog:
> V2:
> - Optimize commit log
> - Rebase on riscv for-next (20230127)
>
> V1:
> https://lore.kernel.org/linux-riscv/20221023133205.3493564-2-guoren@kernel.org/
> ---
> arch/riscv/mm/cacheflush.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c
> index 3cc07ed45aeb..fcd6145fbead 100644
> --- a/arch/riscv/mm/cacheflush.c
> +++ b/arch/riscv/mm/cacheflush.c
> @@ -90,8 +90,10 @@ void flush_icache_pte(pte_t pte)
> if (PageHuge(page))
> page = compound_head(page);
>
> - if (!test_and_set_bit(PG_dcache_clean, &page->flags))
> + if (!test_bit(PG_dcache_clean, &page->flags)) {
> flush_icache_all();
> + set_bit(PG_dcache_clean, &page->flags);
> + }
> }
> #endif /* CONFIG_MMU */
>
> --
> 2.36.1
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

Thanks,
drew

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