[PATCH 1/2] riscv: Fixup race condition on PG_dcache_clean in flush_icache_pte

[guoren at kernel.org]

From: Guo Ren <guoren at linux.alibaba.com>

RISC-V follows the arm64 flush_icache_pte mechanism and also includes
its bug. The patch ensures that instructions are observable in a new
mapping. For more details, see 588a513d3425 ("arm64: Fix race condition
on PG_dcache_clean in __sync_icache_dcache()").

Signed-off-by: Guo Ren <guoren at linux.alibaba.com>
Signed-off-by: Guo Ren <guoren at kernel.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Will Deacon <will at kernel.org>
Cc: Steven Price <steven.price at arm.com>
---
 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 6cb7d96ad9c7..7c9f97fa3938 100644
--- a/arch/riscv/mm/cacheflush.c
+++ b/arch/riscv/mm/cacheflush.c
@@ -82,7 +82,9 @@ void flush_icache_pte(pte_t pte)
 {
 	struct page *page = pte_page(pte);
 
-	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