[PATCH v2 11/11] m68k/tlb: Fix __p*_free_tlb()

From: Peter Zijlstra <peterz@infradead.org>
To: Will Deacon <will@kernel.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Nick Piggin <npiggin@gmail.com>,
	Peter Zijlstra <peterz@infradead.org>
Cc: linux-arch@vger.kernel.org, linux-sh@vger.kernel.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	Rich Felker <dalias@libc.org>,
	"David S. Miller" <davem@davemloft.net>,
	Helge Deller <deller@gmx.de>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Paul Burton <paulburton@kernel.org>,
	Tony Luck <tony.luck@intel.com>,
	Richard Henderson <rth@twiddle.net>,
	Nick Hu <nickhu@andestech.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
	Christoph Hellwig <hch@lst.de>
Subject: [PATCH v2 11/11] m68k/tlb: Fix __p*_free_tlb()
Date: Fri, 17 Jul 2020 11:10:16 +0000	[thread overview]
Message-ID: <20200717111350.001250805@infradead.org> (raw)
In-Reply-To: 20200717111005.024867618@infradead.org

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.

The Motorola MMU has funny PMD stuff, so use a custom table freeer.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/m68k/Kconfig                        |    1 +
 arch/m68k/include/asm/mcf_pgalloc.h      |   14 ++++++--------
 arch/m68k/include/asm/motorola_pgalloc.h |   10 ++++++----
 arch/m68k/mm/motorola.c                  |   17 +++++++++++++++++
 4 files changed, 30 insertions(+), 12 deletions(-)

--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -32,6 +32,7 @@ config M68K
 	select OLD_SIGSUSPEND3
 	select OLD_SIGACTION
 	select MMU_GATHER_NO_RANGE if MMU
+	select MMU_GATHER_TABLE_FREE if MMU_MOTOROLA
 
 config CPU_BIG_ENDIAN
 	def_bool y
--- a/arch/m68k/include/asm/mcf_pgalloc.h
+++ b/arch/m68k/include/asm/mcf_pgalloc.h
@@ -34,14 +34,12 @@ extern inline pmd_t *pmd_alloc_kernel(pg
 
 #define pmd_pgtable(pmd) pfn_to_virt(pmd_val(pmd) >> PAGE_SHIFT)
 
-static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pgtable,
-				  unsigned long address)
-{
-	struct page *page = virt_to_page(pgtable);
-
-	pgtable_pte_page_dtor(page);
-	__free_page(page);
-}
+#define __pte_free_tlb(tlb, pgtable, addr)		\
+do {							\
+	struct page *page = virt_to_page(pgtable);	\
+	pgtable_pte_page_dtor(page);			\
+	tlb_remove_page((tlb), page);			\
+} while (0)
 
 static inline pgtable_t pte_alloc_one(struct mm_struct *mm)
 {
--- a/arch/m68k/include/asm/motorola_pgalloc.h
+++ b/arch/m68k/include/asm/motorola_pgalloc.h
@@ -14,6 +14,8 @@ enum m68k_table_types {
 	TABLE_PTE = 1,
 };
 
+extern void pgtable_free_tlb(struct mmu_gather *tlb, void *table, int type);
+extern void __tlb_remove_table(void *table);
 extern void init_pointer_table(void *table, int type);
 extern void *get_pointer_table(int type);
 extern int free_pointer_table(void *table, int type);
@@ -47,7 +49,7 @@ static inline void pte_free(struct mm_st
 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pgtable,
 				  unsigned long address)
 {
-	free_pointer_table(pgtable, TABLE_PTE);
+	pgtable_free_tlb(tlb, pgtable, TABLE_PTE);
 }
 
 
@@ -61,10 +63,10 @@ static inline int pmd_free(struct mm_str
 	return free_pointer_table(pmd, TABLE_PMD);
 }
 
-static inline int __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
-				 unsigned long address)
+static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
+				  unsigned long address)
 {
-	return free_pointer_table(pmd, TABLE_PMD);
+	pgtable_free_tlb(tlb, pmd, TABLE_PMD);
 }
 
 
--- a/arch/m68k/mm/motorola.c
+++ b/arch/m68k/mm/motorola.c
@@ -215,6 +215,23 @@ int free_pointer_table(void *table, int
 	return 0;
 }
 
+void pgtable_free_tlb(struct mmu_gather *tlb, void *table, int type)
+{
+	unsigned long ptr = (unsigned long)table;
+	BUG_ON(type > 1);
+	BUG_ON(ptr  & 1);
+	ptr |= type;
+	tlb_remove_table(tlb, (void *)ptr);
+}
+
+void __tlb_remove_table(void *table)
+{
+	int type = (unsigned long)table & 1;
+	table = (void *)((unsigned long)table & ~1);
+
+	free_pointer_table(table, type);
+}
+
 /* size of memory already mapped in head.S */
 extern __initdata unsigned long m68k_init_mapped_size;
 
