linux-kernel - [PATCH 17/17] riscv/tlb: Fix __p*_free

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Message-Id: <20191211122956.629995180@infradead.org>
Date:   Wed, 11 Dec 2019 13:07:30 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Will Deacon <will@...nel.org>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Nick Piggin <npiggin@...il.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     linux-arch@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>,
        "David S. Miller" <davem@...emloft.net>,
        Helge Deller <deller@....de>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Paul Burton <paulburton@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        Richard Henderson <rth@...ddle.net>,
        Nick Hu <nickhu@...estech.com>,
        Paul Walmsley <paul.walmsley@...ive.com>
Subject: [PATCH 17/17] riscv/tlb: Fix __p*_free_tlb()

Just like regular pages, page directories need to observe the
following order:

 1) unhook
 2) TLB invalidate
 3) free

to ensure it is safe against concurrent accesses.

Since RISC-V has page based PMDs, no software walkers and IPI based
TLB invalidation, it can use the simple tlb_remove_page() based
freeer.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/riscv/include/asm/pgalloc.h |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

--- a/arch/riscv/include/asm/pgalloc.h
+++ b/arch/riscv/include/asm/pgalloc.h
@@ -73,14 +73,15 @@ static inline void pmd_free(struct mm_st
 	free_page((unsigned long)pmd);
 }
 
-#define __pmd_free_tlb(tlb, pmd, addr)  pmd_free((tlb)->mm, pmd)
+#define __pmd_free_tlb(tlb, pmd, addr)	\
+	tlb_remove_table((tlb), virt_to_page(pmd))
 
 #endif /* __PAGETABLE_PMD_FOLDED */
 
-#define __pte_free_tlb(tlb, pte, buf)   \
-do {                                    \
-	pgtable_pte_page_dtor(pte);     \
-	tlb_remove_page((tlb), pte);    \
+#define __pte_free_tlb(tlb, pte, buf)	\
+do {					\
+	pgtable_pte_page_dtor(pte);	\
+	tlb_remove_table((tlb), (pte));	\
 } while (0)
 #endif /* CONFIG_MMU */