sh: Definitions for 3-level page table layout
If using 64-bit PTEs and 4K pages then each page table has 512 entries
(as opposed to 1024 entries with 32-bit PTEs). Unlike MIPS, SH follows
the convention that all structures in the page table (pgd_t, pmd_t,
pgprot_t, etc) must be the same size. Therefore, 64-bit PTEs require
64-bit PGD entries, etc. Using 2-levels of page tables and 64-bit PTEs
it is only possible to map 1GB of virtual address space.
In order to map all 4GB of virtual address space we need to adopt a
3-level page table layout. This actually works out better for
CONFIG_SUPERH32 because we only waste 2 PGD entries on the P1 and P2
areas (which are untranslated) instead of 256.
Signed-off-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/include/asm/pgalloc.h b/arch/sh/include/asm/pgalloc.h
index fe9f037..4ea2785 100644
--- a/arch/sh/include/asm/pgalloc.h
+++ b/arch/sh/include/asm/pgalloc.h
@@ -6,7 +6,11 @@
#define QUICK_PT 1 /* Other page table pages that are zero on free */
+#ifdef CONFIG_PGTABLE_LEVELS_3
+#include <asm/pgalloc_pmd.h>
+#else
#include <asm/pgalloc_nopmd.h>
+#endif
static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
pte_t *pte)
diff --git a/arch/sh/include/asm/pgalloc_pmd.h b/arch/sh/include/asm/pgalloc_pmd.h
new file mode 100644
index 0000000..20f75cc
--- /dev/null
+++ b/arch/sh/include/asm/pgalloc_pmd.h
@@ -0,0 +1,41 @@
+#ifndef __ASM_SH_PGALLOC_PMD_H
+#define __ASM_SH_PGALLOC_PMD_H
+
+static inline pgd_t *pgd_alloc(struct mm_struct *mm)
+{
+ pgd_t *pgd;
+ int i;
+
+ pgd = kzalloc(sizeof(*pgd) * PTRS_PER_PGD, GFP_KERNEL | __GFP_REPEAT);
+
+ for (i = USER_PTRS_PER_PGD; i < PTRS_PER_PGD; i++)
+ pgd[i] = swapper_pg_dir[i];
+
+ return pgd;
+}
+
+static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
+{
+ kfree(pgd);
+}
+
+static inline void __check_pgt_cache(void)
+{
+}
+
+static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
+{
+ set_pud(pud, __pud((unsigned long)pmd));
+}
+
+static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
+{
+ return quicklist_alloc(QUICK_PT, GFP_KERNEL | __GFP_REPEAT, NULL);
+}
+
+static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
+{
+ quicklist_free(QUICK_PT, NULL, pmd);
+}
+
+#endif /* __ASM_SH_PGALLOC_PMD_H */
diff --git a/arch/sh/include/asm/pgtable.h b/arch/sh/include/asm/pgtable.h
index 9a0f66c..9effcc3 100644
--- a/arch/sh/include/asm/pgtable.h
+++ b/arch/sh/include/asm/pgtable.h
@@ -12,7 +12,11 @@
#ifndef __ASM_SH_PGTABLE_H
#define __ASM_SH_PGTABLE_H
+#ifdef CONFIG_PGTABLE_LEVELS_3
+#include <asm/pgtable_pmd.h>
+#else
#include <asm/pgtable_nopmd.h>
+#endif
#include <asm/page.h>
#ifndef __ASSEMBLY__
diff --git a/arch/sh/include/asm/pgtable_pmd.h b/arch/sh/include/asm/pgtable_pmd.h
new file mode 100644
index 0000000..78dc36e
--- /dev/null
+++ b/arch/sh/include/asm/pgtable_pmd.h
@@ -0,0 +1,55 @@
+#ifndef __ASM_SH_PGTABLE_PMD_H
+#define __ASM_SH_PGTABLE_PMD_H
+
+#include <asm-generic/pgtable-nopud.h>
+
+/*
+ * Some cores need a 3-level page table layout, for example when using
+ * 64-bit PTEs and 4K pages.
+ */
+
+#define PTE_MAGNITUDE 3 /* 64-bit PTEs on extended mode SH-X2 TLB */
+
+/* PGD bits */
+#define PGDIR_SHIFT 30
+
+#define PTRS_PER_PGD 4
+#define USER_PTRS_PER_PGD 2
+
+/* PMD bits */
+#define PMD_SHIFT (PAGE_SHIFT + (PAGE_SHIFT - 3))
+#define PMD_SIZE (1UL << PMD_SHIFT)
+#define PMD_MASK (~(PMD_SIZE-1))
+
+#define PTRS_PER_PMD (PAGE_SIZE / sizeof(pmd_t))
+
+#define pmd_ERROR(e) \
+ printk("%s:%d: bad pmd %016llx.\n", __FILE__, __LINE__, pmd_val(e))
+
+typedef struct { unsigned long long pmd; } pmd_t;
+#define pmd_val(x) ((x).pmd)
+#define __pmd(x) ((pmd_t) { (x) } )
+
+static inline unsigned long pud_page_vaddr(pud_t pud)
+{
+ return pud_val(pud);
+}
+
+#define pmd_index(address) (((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
+static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
+{
+ return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(address);
+}
+
+#define pud_none(x) (!pud_val(x))
+#define pud_present(x) (pud_val(x))
+#define pud_clear(xp) do { set_pud(xp, __pud(0)); } while (0)
+#define pud_bad(x) (pud_val(x) & ~PAGE_MASK)
+
+/*
+ * (puds are folded into pgds so this doesn't get actually called,
+ * but the define is needed for a generic inline function.)
+ */
+#define set_pud(pudptr, pudval) do { *(pudptr) = (pudval); } while(0)
+
+#endif /* __ASM_SH_PGTABLE_PMD_H */
diff --git a/arch/sh/mm/Kconfig b/arch/sh/mm/Kconfig
index 0e7ba8e8..b3f6c1a 100644
--- a/arch/sh/mm/Kconfig
+++ b/arch/sh/mm/Kconfig
@@ -190,19 +190,37 @@
depends on MEMORY_HOTPLUG
choice
+ prompt "Page table layout"
+ default PGTABLE_LEVELS_3 if X2TLB
+ default PGTABLE_LEVELS_2
+
+config PGTABLE_LEVELS_2
+ bool "2 Levels"
+ help
+ This is the default page table layout for all SuperH CPUs.
+
+config PGTABLE_LEVELS_3
+ bool "3 Levels"
+ depends on X2TLB
+ help
+ This enables a 3 level page table structure.
+
+endchoice
+
+choice
prompt "Kernel page size"
default PAGE_SIZE_8KB if X2TLB
default PAGE_SIZE_4KB
config PAGE_SIZE_4KB
bool "4kB"
- depends on !MMU || !X2TLB
+ depends on !MMU || !X2TLB || PGTABLE_LEVELS_3
help
This is the default page size used by all SuperH CPUs.
config PAGE_SIZE_8KB
bool "8kB"
- depends on !MMU || X2TLB
+ depends on !MMU || X2TLB && !PGTABLE_LEVELS_3
help
This enables 8kB pages as supported by SH-X2 and later MMUs.
@@ -214,7 +232,7 @@
config PAGE_SIZE_64KB
bool "64kB"
- depends on !MMU || CPU_SH4 || CPU_SH5
+ depends on !MMU || CPU_SH4 && !PGTABLE_LEVELS_3 || CPU_SH5
help
This enables support for 64kB pages, possible on all SH-4
CPUs and later.
diff --git a/arch/sh/mm/fault_32.c b/arch/sh/mm/fault_32.c
index 4753010..28e2283 100644
--- a/arch/sh/mm/fault_32.c
+++ b/arch/sh/mm/fault_32.c
@@ -53,6 +53,9 @@
if (!pud_present(*pud_k))
return NULL;
+ if (!pud_present(*pud))
+ set_pud(pud, *pud_k);
+
pmd = pmd_offset(pud, address);
pmd_k = pmd_offset(pud_k, address);
if (!pmd_present(*pmd_k))
diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
index 432acd0..761910d 100644
--- a/arch/sh/mm/init.c
+++ b/arch/sh/mm/init.c
@@ -120,7 +120,13 @@
for ( ; (i < PTRS_PER_PGD) && (vaddr != end); pgd++, i++) {
pud = (pud_t *)pgd;
for ( ; (j < PTRS_PER_PUD) && (vaddr != end); pud++, j++) {
+#ifdef __PAGETABLE_PMD_FOLDED
pmd = (pmd_t *)pud;
+#else
+ pmd = (pmd_t *)alloc_bootmem_low_pages(PAGE_SIZE);
+ pud_populate(&init_mm, pud, pmd);
+ pmd += k;
+#endif
for (; (k < PTRS_PER_PMD) && (vaddr != end); pmd++, k++) {
if (pmd_none(*pmd)) {
pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
