linux-kernel - [PATCH 16/17] nds32/tlb: Fix __p*_free

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Message-Id: <20191211122956.572325873@infradead.org>
Date:   Wed, 11 Dec 2019 13:07:29 +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 16/17] nds32/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.

Even though NDS32 is UP only, we still need to observe this order
because mmu_gather is preemptible.

NDS32 does not in fact have PMDs.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/nds32/include/asm/tlb.h |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/arch/nds32/include/asm/tlb.h
+++ b/arch/nds32/include/asm/tlb.h
@@ -6,7 +6,12 @@
 
 #include <asm-generic/tlb.h>
 
-#define __pte_free_tlb(tlb, pte, addr)	pte_free((tlb)->mm, pte)
+#define __pte_free_tlb(tlb, pte, address)	\
+do {						\
+	pgtable_pte_page_dtor(pte);		\
+	tlb_remove_table((tlb), (pte));		\
+} while (0)
+
 #define __pmd_free_tlb(tlb, pmd, addr)	pmd_free((tln)->mm, pmd)
 
 #endif