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From: Peter Zijlstra <peterz@infradead.org>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: linux-m68k@lists.linux-m68k.org, linux-kernel@vger.kernel.org,
	Will Deacon <will@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Michael Schmitz <schmitzmic@gmail.com>,
	Greg Ungerer <gerg@linux-m68k.org>
Subject: [PATCH -v2 07/10] m68k,mm: Use table allocator for pgtables
Date: Fri, 31 Jan 2020 13:45:38 +0100	[thread overview]
Message-ID: <20200131125403.825295149@infradead.org> (raw)
In-Reply-To: 20200131124531.623136425@infradead.org

With the new page-table layout, using full (4k) pages for (256 byte)
pte-tables is immensely wastefull. Move the pte-tables over to the
same allocator already used for the (512 byte) higher level tables
(pgd/pmd).

This reduces the pte-table waste from 15x to 2x.

Due to no longer being bound to 16 consecutive tables, this might
actually already be more efficient than the old code for sparse
tables.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/m68k/include/asm/motorola_pgalloc.h |   44 ++++++-------------------------
 arch/m68k/include/asm/motorola_pgtable.h |    8 ++++-
 arch/m68k/include/asm/page.h             |    5 +++
 3 files changed, 21 insertions(+), 36 deletions(-)

--- a/arch/m68k/include/asm/motorola_pgalloc.h
+++ b/arch/m68k/include/asm/motorola_pgalloc.h
@@ -13,54 +13,28 @@ extern int free_pointer_table(pmd_t *);
 
 static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
 {
-	pte_t *pte;
-
-	pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
-	if (pte)
-		mmu_page_ctor(pte);
-
-	return pte;
+	return (pte_t *)get_pointer_table();
 }
 
 static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
 {
-	mmu_page_dtor(pte);
-	free_page((unsigned long) pte);
+	free_pointer_table((void *)pte);
 }
 
 static inline pgtable_t pte_alloc_one(struct mm_struct *mm)
 {
-	struct page *page;
-
-	page = alloc_pages(GFP_KERNEL|__GFP_ZERO, 0);
-	if(!page)
-		return NULL;
-	if (!pgtable_pte_page_ctor(page)) {
-		__free_page(page);
-		return NULL;
-	}
-
-	mmu_page_ctor(kmap(page));
-	kunmap(page);
-
-	return page;
+	return (pte_t *)get_pointer_table();
 }
 
-static inline void pte_free(struct mm_struct *mm, pgtable_t page)
+static inline void pte_free(struct mm_struct *mm, pgtable_t pgtable)
 {
-	pgtable_pte_page_dtor(page);
-	mmu_page_dtor(kmap(page));
-	kunmap(page);
-	__free_page(page);
+	free_pointer_table((void *)pgtable);
 }
 
-static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t page,
+static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pgtable,
 				  unsigned long address)
 {
-	pgtable_pte_page_dtor(page);
-	mmu_page_dtor(kmap(page));
-	kunmap(page);
-	__free_page(page);
+	free_pointer_table((void *)pgtable);
 }
 
 
@@ -99,9 +73,9 @@ static inline void pmd_populate_kernel(s
 
 static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd, pgtable_t page)
 {
-	pmd_set(pmd, page_address(page));
+	pmd_set(pmd, page);
 }
-#define pmd_pgtable(pmd) pmd_page(pmd)
+#define pmd_pgtable(pmd) ((pgtable_t)__pmd_page(pmd))
 
 static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
 {
--- a/arch/m68k/include/asm/motorola_pgtable.h
+++ b/arch/m68k/include/asm/motorola_pgtable.h
@@ -144,7 +144,13 @@ static inline void pud_set(pud_t *pudp,
 #define pmd_bad(pmd)		((pmd_val(pmd) & _DESCTYPE_MASK) != _PAGE_TABLE)
 #define pmd_present(pmd)	(pmd_val(pmd) & _PAGE_TABLE)
 #define pmd_clear(pmdp)		({ pmd_val(*pmdp) = 0; })
-#define pmd_page(pmd)		virt_to_page(__va(pmd_val(pmd)))
+
+/*
+ * m68k does not have huge pages (020/030 actually could), but generic code
+ * expects pmd_page() to exists, only to then DCE it all. Provide a dummy to
+ * make the compiler happy.
+ */
+#define pmd_page(pmd)		NULL
 
 
 #define pud_none(pud)		(!pud_val(pud))
--- a/arch/m68k/include/asm/page.h
+++ b/arch/m68k/include/asm/page.h
@@ -30,7 +30,12 @@ typedef struct { unsigned long pmd; } pm
 typedef struct { unsigned long pte; } pte_t;
 typedef struct { unsigned long pgd; } pgd_t;
 typedef struct { unsigned long pgprot; } pgprot_t;
+
+#if defined(CONFIG_SUN3) || defined(CONFIG_COLDFIRE)
 typedef struct page *pgtable_t;
+#else
+typedef pte_t *pgtable_t;
+#endif
 
 #define pte_val(x)	((x).pte)
 #define pgd_val(x)	((x).pgd)



  parent reply	other threads:[~2020-01-31 12:56 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-31 12:45 [PATCH -v2 00/10] Rewrite Motorola MMU page-table layout Peter Zijlstra
2020-01-31 12:45 ` [PATCH -v2 01/10] m68k,mm: Remove stray nocache in ColdFire pgalloc Peter Zijlstra
2020-01-31 12:45 ` [PATCH -v2 02/10] m68k,mm: Fix ColdFire pgd_alloc() Peter Zijlstra
2020-01-31 12:45 ` [PATCH -v2 03/10] m68k,mm: Unify Motorola MMU page setup Peter Zijlstra
2020-01-31 12:45 ` [PATCH -v2 04/10] m68k,mm: Move the pointer table allocator to motorola.c Peter Zijlstra
2020-01-31 12:45 ` [PATCH -v2 05/10] m68k,mm: Restructure Motorola MMU page-table layout Peter Zijlstra
2020-01-31 12:45 ` [PATCH -v2 06/10] m68k,mm: Improve kernel_page_table() Peter Zijlstra
2020-01-31 12:45 ` Peter Zijlstra [this message]
2020-01-31 12:45 ` [PATCH -v2 08/10] m68k,mm: Extend table allocator for multiple sizes Peter Zijlstra
2020-02-07 10:56   ` Geert Uytterhoeven
2020-02-07 11:34     ` Peter Zijlstra
2020-02-07 12:11       ` Geert Uytterhoeven
2020-02-07 12:30         ` Checkpatch being daft, Was: " Peter Zijlstra
2020-02-07 12:33           ` Peter Zijlstra
2020-02-09 18:24             ` Joe Perches
2020-02-10 16:38               ` Peter Zijlstra
2020-02-10 17:12                 ` Joe Perches
2020-02-07 12:57           ` Joe Perches
2020-01-31 12:45 ` [PATCH -v2 09/10] m68k,mm: Fully initialize the page-table allocator Peter Zijlstra
2020-02-07 10:58   ` Geert Uytterhoeven
2020-02-07 11:37     ` Peter Zijlstra
2020-01-31 12:45 ` [PATCH -v2 10/10] m68k,mm: Change ColdFire pgtable_t Peter Zijlstra
2020-01-31 13:19 ` [PATCH -v2 00/10] Rewrite Motorola MMU page-table layout Greg Ungerer
2020-02-03  1:20   ` Greg Ungerer
2020-02-01  8:07 ` Michael Schmitz
2020-02-03  9:50 ` Will Deacon
2020-02-10 11:16 ` Geert Uytterhoeven
2020-03-09 10:15   ` Geert Uytterhoeven
2020-03-09 11:46     ` Peter Zijlstra

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