m68k: mm: Extend table allocator for multiple sizes

In addition to the PGD/PMD table size (128*4) add a PTE table size
(64*4) to the table allocator. This completely removes the pte-table
overhead compared to the old code, even for dense tables.

Notes:

 - the allocator gained a list_empty() check to deal with there not
   being any pages at all.

 - the free mask is extended to cover more than the 8 bits required
   for the (512 byte) PGD/PMD tables.

 - NR_PAGETABLE accounting is restored.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Greg Ungerer <gerg@linux-m68k.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Tested-by: Greg Ungerer <gerg@linux-m68k.org>
Link: https://lore.kernel.org/r/20200131125403.882175409@infradead.org
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

diff --git a/arch/m68k/include/asm/motorola_pgalloc.h b/arch/m68k/include/asm/motorola_pgalloc.h
index c15e04277be7fca58752b08978f39960e7265c0d..c66e429179122f7a05b78bb6537c26a8f2700a23 100644 (file)
--- a/arch/m68k/include/asm/motorola_pgalloc.h
+++ b/arch/m68k/include/asm/motorola_pgalloc.h
@@ -8,61 +8,68 @@
 extern void mmu_page_ctor(void *page);
 extern void mmu_page_dtor(void *page);
 
-extern pmd_t *get_pointer_table(void);
-extern int free_pointer_table(pmd_t *);
+enum m68k_table_types {
+       TABLE_PGD = 0,
+       TABLE_PMD = 0, /* same size as PGD */
+       TABLE_PTE = 1,
+};
+
+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);
 
 static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
 {
-       return (pte_t *)get_pointer_table();
+       return get_pointer_table(TABLE_PTE);
 }
 
 static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
 {
-       free_pointer_table((void *)pte);
+       free_pointer_table(pte, TABLE_PTE);
 }
 
 static inline pgtable_t pte_alloc_one(struct mm_struct *mm)
 {
-       return (pte_t *)get_pointer_table();
+       return get_pointer_table(TABLE_PTE);
 }
 
 static inline void pte_free(struct mm_struct *mm, pgtable_t pgtable)
 {
-       free_pointer_table((void *)pgtable);
+       free_pointer_table(pgtable, TABLE_PTE);
 }
 
 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pgtable,
                                  unsigned long address)
 {
-       free_pointer_table((void *)pgtable);
+       free_pointer_table(pgtable, TABLE_PTE);
 }
 
 
 static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
 {
-       return get_pointer_table();
+       return get_pointer_table(TABLE_PMD);
 }
 
 static inline int pmd_free(struct mm_struct *mm, pmd_t *pmd)
 {
-       return free_pointer_table(pmd);
+       return free_pointer_table(pmd, TABLE_PMD);
 }
 
 static inline int __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
                                 unsigned long address)
 {
-       return free_pointer_table(pmd);
+       return free_pointer_table(pmd, TABLE_PMD);
 }
 
 
 static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 {
-       pmd_free(mm, (pmd_t *)pgd);
+       free_pointer_table(pgd, TABLE_PGD);
 }
 
 static inline pgd_t *pgd_alloc(struct mm_struct *mm)
 {
-       return (pgd_t *)get_pointer_table();
+       return get_pointer_table(TABLE_PGD);
 }
 
 

diff --git a/arch/m68k/mm/init.c b/arch/m68k/mm/init.c
index a9b6d26cff8a151865d85aa978a02f95165ff492..3e3a74a5b215bf30619debe872f3db392193c9d5 100644 (file)
--- a/arch/m68k/mm/init.c
+++ b/arch/m68k/mm/init.c
@@ -40,10 +40,6 @@
 void *empty_zero_page;
 EXPORT_SYMBOL(empty_zero_page);
 
-#if !defined(CONFIG_SUN3) && !defined(CONFIG_COLDFIRE)
-extern void init_pointer_table(unsigned long ptable);
-#endif
-
 #ifdef CONFIG_MMU
 
 pg_data_t pg_data_map[MAX_NUMNODES];
@@ -127,12 +123,16 @@ static inline void init_pointer_tables(void)
        int i;
 
        /* insert pointer tables allocated so far into the tablelist */
-       init_pointer_table((unsigned long)kernel_pg_dir);
+       init_pointer_table(kernel_pg_dir, TABLE_PGD);
        for (i = 0; i < PTRS_PER_PGD; i++) {
-               pud_t *pud = (pud_t *)(&kernel_pg_dir[i]);
+               pud_t *pud = (pud_t *)&kernel_pg_dir[i];
+               pmd_t *pmd_dir;
+
+               if (!pud_present(*pud))
+                       continue;
 
-               if (pud_present(*pud))
-                       init_pointer_table(pgd_page_vaddr(kernel_pg_dir[i]));
+               pmd_dir = (pmd_t *)pgd_page_vaddr(kernel_pg_dir[i]);
+               init_pointer_table(pmd_dir, TABLE_PMD);
        }
 #endif
 }

diff --git a/arch/m68k/mm/motorola.c b/arch/m68k/mm/motorola.c
index 600f9c1d96f8492d3edc256e2c1d4efbb4f7557c..fc16190ec2d660225a841b28b0b7278051ea263c 100644 (file)
--- a/arch/m68k/mm/motorola.c
+++ b/arch/m68k/mm/motorola.c
@@ -72,24 +72,35 @@ void mmu_page_dtor(void *page)
    arch/sparc/mm/srmmu.c ... */
 
 typedef struct list_head ptable_desc;
-static LIST_HEAD(ptable_list);
+
+static struct list_head ptable_list[2] = {
+       LIST_HEAD_INIT(ptable_list[0]),
+       LIST_HEAD_INIT(ptable_list[1]),
+};
 
 #define PD_PTABLE(page) ((ptable_desc *)&(virt_to_page(page)->lru))
 #define PD_PAGE(ptable) (list_entry(ptable, struct page, lru))
-#define PD_MARKBITS(dp) (*(unsigned char *)&PD_PAGE(dp)->index)
+#define PD_MARKBITS(dp) (*(unsigned int *)&PD_PAGE(dp)->index)
+
+static const int ptable_shift[2] = {
+       7+2, /* PGD, PMD */
+       6+2, /* PTE */
+};
 
-#define PTABLE_SIZE (PTRS_PER_PMD * sizeof(pmd_t))
+#define ptable_size(type) (1U << ptable_shift[type])
+#define ptable_mask(type) ((1U << (PAGE_SIZE / ptable_size(type))) - 1)
 
-void __init init_pointer_table(unsigned long ptable)
+void __init init_pointer_table(void *table, int type)
 {
        ptable_desc *dp;
+       unsigned long ptable = (unsigned long)table;
        unsigned long page = ptable & PAGE_MASK;
-       unsigned char mask = 1 << ((ptable - page)/PTABLE_SIZE);
+       unsigned int mask = 1U << ((ptable - page)/ptable_size(type));
 
        dp = PD_PTABLE(page);
        if (!(PD_MARKBITS(dp) & mask)) {
-               PD_MARKBITS(dp) = 0xff;
-               list_add(dp, &ptable_list);
+               PD_MARKBITS(dp) = ptable_mask(type);
+               list_add(dp, &ptable_list[type]);
        }
 
        PD_MARKBITS(dp) &= ~mask;
@@ -102,12 +113,11 @@ void __init init_pointer_table(unsigned long ptable)
        return;
 }
 
-pmd_t *get_pointer_table (void)
+void *get_pointer_table(int type)
 {
-       ptable_desc *dp = ptable_list.next;
-       unsigned char mask = PD_MARKBITS (dp);
-       unsigned char tmp;
-       unsigned int off;
+       ptable_desc *dp = ptable_list[type].next;
+       unsigned int mask = list_empty(&ptable_list[type]) ? 0 : PD_MARKBITS(dp);
+       unsigned int tmp, off;
 
        /*
         * For a pointer table for a user process address space, a
@@ -122,30 +132,39 @@ pmd_t *get_pointer_table (void)
                if (!(page = (void *)get_zeroed_page(GFP_KERNEL)))
                        return NULL;
 
+               if (type == TABLE_PTE) {
+                       /*
+                        * m68k doesn't have SPLIT_PTE_PTLOCKS for not having
+                        * SMP.
+                        */
+                       pgtable_pte_page_ctor(virt_to_page(page));
+               }
+
                mmu_page_ctor(page);
 
                new = PD_PTABLE(page);
-               PD_MARKBITS(new) = 0xfe;
+               PD_MARKBITS(new) = ptable_mask(type) - 1;
                list_add_tail(new, dp);
 
                return (pmd_t *)page;
        }
 
-       for (tmp = 1, off = 0; (mask & tmp) == 0; tmp <<= 1, off += PTABLE_SIZE)
+       for (tmp = 1, off = 0; (mask & tmp) == 0; tmp <<= 1, off += ptable_size(type))
                ;
        PD_MARKBITS(dp) = mask & ~tmp;
        if (!PD_MARKBITS(dp)) {
                /* move to end of list */
-               list_move_tail(dp, &ptable_list);
+               list_move_tail(dp, &ptable_list[type]);
        }
-       return (pmd_t *) (page_address(PD_PAGE(dp)) + off);
+       return page_address(PD_PAGE(dp)) + off;
 }
 
-int free_pointer_table (pmd_t *ptable)
+int free_pointer_table(void *table, int type)
 {
        ptable_desc *dp;
-       unsigned long page = (unsigned long)ptable & PAGE_MASK;
-       unsigned char mask = 1 << (((unsigned long)ptable - page)/PTABLE_SIZE);
+       unsigned long ptable = (unsigned long)table;
+       unsigned long page = ptable & PAGE_MASK;
+       unsigned int mask = 1U << ((ptable - page)/ptable_size(type));
 
        dp = PD_PTABLE(page);
        if (PD_MARKBITS (dp) & mask)
@@ -153,18 +172,20 @@ int free_pointer_table (pmd_t *ptable)
 
        PD_MARKBITS (dp) |= mask;
 
-       if (PD_MARKBITS(dp) == 0xff) {
+       if (PD_MARKBITS(dp) == ptable_mask(type)) {
                /* all tables in page are free, free page */
                list_del(dp);
                mmu_page_dtor((void *)page);
+               if (type == TABLE_PTE)
+                       pgtable_pte_page_dtor(virt_to_page(page));
                free_page (page);
                return 1;
-       } else if (ptable_list.next != dp) {
+       } else if (ptable_list[type].next != dp) {
                /*
                 * move this descriptor to the front of the list, since
                 * it has one or more free tables.
                 */
-               list_move(dp, &ptable_list);
+               list_move(dp, &ptable_list[type]);
        }
        return 0;
 }