linux-kernel - [PATCH 10/17] sparc32/tlb: Fix __p*_free

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Message-Id: <20191211122956.227316370@infradead.org>
Date:   Wed, 11 Dec 2019 13:07:23 +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 10/17] sparc32/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.

Because Sparc32 has non-page based page directories, use a custom
table freeer.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/sparc/Kconfig                  |    1 +
 arch/sparc/include/asm/pgalloc_32.h |    7 +++++--
 arch/sparc/mm/srmmu.c               |   28 ++++++++++++++++++++++++++++
 3 files changed, 34 insertions(+), 2 deletions(-)

--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -57,6 +57,7 @@ config SPARC32
 	select CLZ_TAB
 	select HAVE_UID16
 	select OLD_SIGACTION
+	select MMU_GATHER_TABLE_FREE
 
 config SPARC64
 	def_bool 64BIT
--- a/arch/sparc/include/asm/pgalloc_32.h
+++ b/arch/sparc/include/asm/pgalloc_32.h
@@ -12,6 +12,9 @@
 
 struct page;
 
+extern void pgtable_free_tlb(struct mmu_gather *tlb, void *table, int idx);
+extern void __tlb_remove_table(void *table);
+
 void *srmmu_get_nocache(int size, int align);
 void srmmu_free_nocache(void *addr, int size);
 
@@ -48,7 +51,7 @@ static inline void free_pmd_fast(pmd_t *
 }
 
 #define pmd_free(mm, pmd)		free_pmd_fast(pmd)
-#define __pmd_free_tlb(tlb, pmd, addr)	pmd_free((tlb)->mm, pmd)
+#define __pmd_free_tlb(tlb, pmd, addr)	pgtable_free_tlb((tlb), (pmd), 1)
 
 void pmd_populate(struct mm_struct *mm, pmd_t *pmdp, struct page *ptep);
 #define pmd_pgtable(pmd) pmd_page(pmd)
@@ -72,6 +75,6 @@ static inline void free_pte_fast(pte_t *
 #define pte_free_kernel(mm, pte)	free_pte_fast(pte)
 
 void pte_free(struct mm_struct * mm, pgtable_t pte);
-#define __pte_free_tlb(tlb, pte, addr)	pte_free((tlb)->mm, pte)
+#define __pte_free_tlb(tlb, pte, addr)	pgtable_free_tlb((tlb), (pte), 0)
 
 #endif /* _SPARC_PGALLOC_H */
--- a/arch/sparc/mm/srmmu.c
+++ b/arch/sparc/mm/srmmu.c
@@ -38,6 +38,7 @@
 #include <asm/page.h>
 #include <asm/asi.h>
 #include <asm/smp.h>
+#include <asm/tlb.h>
 #include <asm/io.h>
 
 /* Now the cpu specific definitions. */
@@ -1849,3 +1850,30 @@ void __init load_mmu(void)
 		sun4m_init_smp();
 #endif
 }
+
+#define TLB_IDX_MASK	1UL
+
+void __tlb_remove_table(void *table)
+{
+	void *dir = (void *)((unsigned long)table & ~TLB_IDX_MASK);
+	int idx = (unsigned long)table & TLB_IDX_MASK;
+
+	switch (idx) {
+	case 1: /* PMD */
+		pmd_free(NULL, dir);
+		break;
+	case 0: /* PTE */
+		pte_free(NULL, dir);
+		break;
+	}
+}
+
+void pgtable_free_tlb(struct mmu_gather *tlb, void *table, int idx)
+{
+	unsigned long pgf = (unsigned long)table;
+	BUG_ON(idx > TLB_IDX_MASK);
+	BUG_ON(pgf & TLB_IDX_MASK);
+	pgf |= idx;
+	tlb_remove_table(tlb, (void *)pgf);
+}
+