m68k: mm: Restructure Motorola MMU page-table layout

The Motorola 68xxx MMUs, 040 (and later) have a fixed 7,7,{5,6}
page-table setup, where the last depends on the page-size selected (8k
vs 4k resp.), and head.S selects 4K pages. For 030 (and earlier) we
explicitly program 7,7,6 and 4K pages in %tc.

However, the current code implements this mightily weird. What it does
is group 16 of those (6 bit) pte tables into one 4k page to not waste
space. The down-side is that that forces pmd_t to be a 16-tuple
pointing to consecutive pte tables.

This breaks the generic code which assumes READ_ONCE(*pmd) will be
word sized.

Therefore implement a straight forward 7,7,6 3 level page-table setup,
with the addition (for 020/030) of (partial) large-page support. For
now this increases the memory footprint for pte-tables 15 fold.

Tested with ARAnyM/68040 emulation.

Suggested-by: Will Deacon <will@kernel.org>
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/20200131125403.711478295@infradead.org
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

diff --git a/arch/m68k/include/asm/motorola_pgtable.h b/arch/m68k/include/asm/motorola_pgtable.h
index 62bedc61f110f073830a6ab9561becb3ceea0b72..4d94e462bb2b9c039ad691a7c78b22495744c358 100644 (file)
--- a/arch/m68k/include/asm/motorola_pgtable.h
+++ b/arch/m68k/include/asm/motorola_pgtable.h
@@ -108,13 +108,7 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 
 static inline void pmd_set(pmd_t *pmdp, pte_t *ptep)
 {
-       unsigned long ptbl = virt_to_phys(ptep) | _PAGE_TABLE | _PAGE_ACCESSED;
-       unsigned long *ptr = pmdp->pmd;
-       short i = 16;
-       while (--i >= 0) {
-               *ptr++ = ptbl;
-               ptbl += (sizeof(pte_t)*PTRS_PER_PTE/16);
-       }
+       pmd_val(*pmdp) = virt_to_phys(ptep) | _PAGE_TABLE | _PAGE_ACCESSED;
 }
 
 static inline void pud_set(pud_t *pudp, pmd_t *pmdp)
@@ -138,12 +132,7 @@ static inline void pud_set(pud_t *pudp, pmd_t *pmdp)
 #define pmd_none(pmd)          (!pmd_val(pmd))
 #define pmd_bad(pmd)           ((pmd_val(pmd) & _DESCTYPE_MASK) != _PAGE_TABLE)
 #define pmd_present(pmd)       (pmd_val(pmd) & _PAGE_TABLE)
-#define pmd_clear(pmdp) ({                     \
-       unsigned long *__ptr = pmdp->pmd;       \
-       short __i = 16;                         \
-       while (--__i >= 0)                      \
-               *__ptr++ = 0;                   \
-})
+#define pmd_clear(pmdp)                ({ pmd_val(*pmdp) = 0; })
 #define pmd_page(pmd)          virt_to_page(__va(pmd_val(pmd)))
 
 

diff --git a/arch/m68k/include/asm/page.h b/arch/m68k/include/asm/page.h
index 05e1e1e77a9a76e4c1771e8a7bb60fb57d7317cc..c02326b56ae29b89c4b5fa98173a8be56faeb995 100644 (file)
--- a/arch/m68k/include/asm/page.h
+++ b/arch/m68k/include/asm/page.h
@@ -22,9 +22,9 @@
  * These are used to make use of C type-checking..
  */
 #if !defined(CONFIG_MMU) || CONFIG_PGTABLE_LEVELS == 3
-typedef struct { unsigned long pmd[16]; } pmd_t;
-#define pmd_val(x)     ((&x)->pmd[0])
-#define __pmd(x)       ((pmd_t) { { (x) }, })
+typedef struct { unsigned long pmd; } pmd_t;
+#define pmd_val(x)     ((&x)->pmd)
+#define __pmd(x)       ((pmd_t) { (x) } )
 #endif
 
 typedef struct { unsigned long pte; } pte_t;

diff --git a/arch/m68k/include/asm/pgtable_mm.h b/arch/m68k/include/asm/pgtable_mm.h
index 2bf5c3501e7870c99c4c2bd5066baed63fc72245..f0e5167de834a5a7e7291aba3c3c5f2cbb56484e 100644 (file)
--- a/arch/m68k/include/asm/pgtable_mm.h
+++ b/arch/m68k/include/asm/pgtable_mm.h
@@ -36,7 +36,7 @@
 
 /* PMD_SHIFT determines the size of the area a second-level page table can map */
 #if CONFIG_PGTABLE_LEVELS == 3
-#define PMD_SHIFT      22
+#define PMD_SHIFT      18
 #endif
 #define PMD_SIZE       (1UL << PMD_SHIFT)
 #define PMD_MASK       (~(PMD_SIZE-1))
@@ -67,8 +67,8 @@
 #define PTRS_PER_PMD   1
 #define PTRS_PER_PGD   1024
 #else
-#define PTRS_PER_PTE   1024
-#define PTRS_PER_PMD   8
+#define PTRS_PER_PTE   64
+#define PTRS_PER_PMD   128
 #define PTRS_PER_PGD   128
 #endif
 #define USER_PTRS_PER_PGD      (TASK_SIZE/PGDIR_SIZE)
@@ -76,8 +76,8 @@
 
 /* Virtual address region for use by kernel_map() */
 #ifdef CONFIG_SUN3
-#define KMAP_START     0x0DC00000
-#define KMAP_END       0x0E000000
+#define KMAP_START     0x0dc00000
+#define KMAP_END       0x0e000000
 #elif defined(CONFIG_COLDFIRE)
 #define KMAP_START     0xe0000000
 #define KMAP_END       0xf0000000

diff --git a/arch/m68k/mm/kmap.c b/arch/m68k/mm/kmap.c
index 120030ad8dc49f70975f9109f91c009a4c7909e5..14d31d216cefe7f77cf3094a2a5102dd83440515 100644 (file)
--- a/arch/m68k/mm/kmap.c
+++ b/arch/m68k/mm/kmap.c
@@ -24,8 +24,6 @@
 
 #undef DEBUG
 
-#define PTRTREESIZE    (256*1024)
-
 /*
  * For 040/060 we can use the virtual memory area like other architectures,
  * but for 020/030 we want to use early termination page descriptors and we
@@ -50,7 +48,7 @@ static inline void free_io_area(void *addr)
 
 #else
 
-#define IO_SIZE                (256*1024)
+#define IO_SIZE                PMD_SIZE
 
 static struct vm_struct *iolist;
 
@@ -81,14 +79,13 @@ static void __free_io_area(void *addr, unsigned long size)
 
 #if CONFIG_PGTABLE_LEVELS == 3
                if (CPU_IS_020_OR_030) {
-                       int pmd_off = (virtaddr/PTRTREESIZE) & 15;
-                       int pmd_type = pmd_dir->pmd[pmd_off] & _DESCTYPE_MASK;
+                       int pmd_type = pmd_val(*pmd_dir) & _DESCTYPE_MASK;
 
                        if (pmd_type == _PAGE_PRESENT) {
-                               pmd_dir->pmd[pmd_off] = 0;
-                               virtaddr += PTRTREESIZE;
-                               size -= PTRTREESIZE;
-                               continue;
+                               pmd_clear(pmd_dir);
+                               virtaddr += PMD_SIZE;
+                               size -= PMD_SIZE;
+
                        } else if (pmd_type == 0)
                                continue;
                }
@@ -249,7 +246,7 @@ void __iomem *__ioremap(unsigned long physaddr, unsigned long size, int cachefla
 
        while ((long)size > 0) {
 #ifdef DEBUG
-               if (!(virtaddr & (PTRTREESIZE-1)))
+               if (!(virtaddr & (PMD_SIZE-1)))
                        printk ("\npa=%#lx va=%#lx ", physaddr, virtaddr);
 #endif
                pgd_dir = pgd_offset_k(virtaddr);
@@ -263,10 +260,10 @@ void __iomem *__ioremap(unsigned long physaddr, unsigned long size, int cachefla
 
 #if CONFIG_PGTABLE_LEVELS == 3
                if (CPU_IS_020_OR_030) {
-                       pmd_dir->pmd[(virtaddr/PTRTREESIZE) & 15] = physaddr;
-                       physaddr += PTRTREESIZE;
-                       virtaddr += PTRTREESIZE;
-                       size -= PTRTREESIZE;
+                       pmd_val(*pmd_dir) = physaddr;
+                       physaddr += PMD_SIZE;
+                       virtaddr += PMD_SIZE;
+                       size -= PMD_SIZE;
                } else
 #endif
                {
@@ -367,13 +364,12 @@ void kernel_set_cachemode(void *addr, unsigned long size, int cmode)
 
 #if CONFIG_PGTABLE_LEVELS == 3
                if (CPU_IS_020_OR_030) {
-                       int pmd_off = (virtaddr/PTRTREESIZE) & 15;
+                       unsigned long pmd = pmd_val(*pmd_dir);
 
-                       if ((pmd_dir->pmd[pmd_off] & _DESCTYPE_MASK) == _PAGE_PRESENT) {
-                               pmd_dir->pmd[pmd_off] = (pmd_dir->pmd[pmd_off] &
-                                                        _CACHEMASK040) | cmode;
-                               virtaddr += PTRTREESIZE;
-                               size -= PTRTREESIZE;
+                       if ((pmd & _DESCTYPE_MASK) == _PAGE_PRESENT) {
+                               *pmd_dir = __pmd((pmd & _CACHEMASK040) | cmode);
+                               virtaddr += PMD_SIZE;
+                               size -= PMD_SIZE;
                                continue;
                        }
                }

diff --git a/arch/m68k/mm/motorola.c b/arch/m68k/mm/motorola.c
index 2102f9397c94365b0da6deb4c633adb0143e8de2..c888ef46da3e14d799f883edebcd8b892ef33378 100644 (file)
--- a/arch/m68k/mm/motorola.c
+++ b/arch/m68k/mm/motorola.c
@@ -236,8 +236,6 @@ static pmd_t * __init kernel_ptr_table(void)
 
 static void __init map_node(int node)
 {
-#define PTRTREESIZE (256*1024)
-#define ROOTTREESIZE (32*1024*1024)
        unsigned long physaddr, virtaddr, size;
        pgd_t *pgd_dir;
        p4d_t *p4d_dir;
@@ -255,21 +253,21 @@ static void __init map_node(int node)
 
        while (size > 0) {
 #ifdef DEBUG
-               if (!(virtaddr & (PTRTREESIZE-1)))
+               if (!(virtaddr & (PMD_SIZE-1)))
                        printk ("\npa=%#lx va=%#lx ", physaddr & PAGE_MASK,
                                virtaddr);
 #endif
                pgd_dir = pgd_offset_k(virtaddr);
                if (virtaddr && CPU_IS_020_OR_030) {
-                       if (!(virtaddr & (ROOTTREESIZE-1)) &&
-                           size >= ROOTTREESIZE) {
+                       if (!(virtaddr & (PGDIR_SIZE-1)) &&
+                           size >= PGDIR_SIZE) {
 #ifdef DEBUG
                                printk ("[very early term]");
 #endif
                                pgd_val(*pgd_dir) = physaddr;
-                               size -= ROOTTREESIZE;
-                               virtaddr += ROOTTREESIZE;
-                               physaddr += ROOTTREESIZE;
+                               size -= PGDIR_SIZE;
+                               virtaddr += PGDIR_SIZE;
+                               physaddr += PGDIR_SIZE;
                                continue;
                        }
                }
@@ -289,8 +287,8 @@ static void __init map_node(int node)
 #ifdef DEBUG
                                printk ("[early term]");
 #endif
-                               pmd_dir->pmd[(virtaddr/PTRTREESIZE) & 15] = physaddr;
-                               physaddr += PTRTREESIZE;
+                               pmd_val(*pmd_dir) = physaddr;
+                               physaddr += PMD_SIZE;
                        } else {
                                int i;
 #ifdef DEBUG
@@ -298,15 +296,15 @@ static void __init map_node(int node)
 #endif
                                zero_pgtable = kernel_ptr_table();
                                pte_dir = (pte_t *)zero_pgtable;
-                               pmd_dir->pmd[0] = virt_to_phys(pte_dir) |
-                                       _PAGE_TABLE | _PAGE_ACCESSED;
+                               pmd_set(pmd_dir, pte_dir);
+
                                pte_val(*pte_dir++) = 0;
                                physaddr += PAGE_SIZE;
-                               for (i = 1; i < 64; physaddr += PAGE_SIZE, i++)
+                               for (i = 1; i < PTRS_PER_PTE; physaddr += PAGE_SIZE, i++)
                                        pte_val(*pte_dir++) = physaddr;
                        }
-                       size -= PTRTREESIZE;
-                       virtaddr += PTRTREESIZE;
+                       size -= PMD_SIZE;
+                       virtaddr += PMD_SIZE;
                } else {
                        if (!pmd_present(*pmd_dir)) {
 #ifdef DEBUG