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authorPeter Zijlstra <peterz@infradead.org>2020-01-31 13:45:37 +0100
committerGeert Uytterhoeven <geert@linux-m68k.org>2020-02-10 10:57:48 +0100
commitef9285f69f0efbc75d01cbb09fe65882effd0a25 (patch)
tree79be6657cea036325005b2be529dac70299383e8 /arch/m68k
parentef22d8abd876e805b604e8f655127de2beee2869 (diff)
m68k: mm: Improve kernel_page_table()
With the PTE-tables now only being 256 bytes, allocating a full page for them is a giant waste. Start by improving the boot time allocator such that init_mm initialization will at least have optimal memory density. Much thanks to Will Deacon in help with debugging and ferreting out lost information on these dusty MMUs. Notes: - _TABLE_MASK is reduced to account for the shorter (256 byte) alignment of pte-tables, per the manual, table entries should only ever have state in the low 4 bits (Used,WrProt,Desc1,Desc0) so it is still longer than strictly required. (Thanks Will!!!) - Also use kernel_page_table() for the 020/030 zero_pgtable case and consequently remove the zero_pgtable init hack (will fix up later). 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/20200131125403.768263973@infradead.org Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Diffstat (limited to 'arch/m68k')
-rw-r--r--arch/m68k/include/asm/motorola_pgtable.h13
-rw-r--r--arch/m68k/mm/init.c5
-rw-r--r--arch/m68k/mm/motorola.c51
3 files changed, 41 insertions, 28 deletions
diff --git a/arch/m68k/include/asm/motorola_pgtable.h b/arch/m68k/include/asm/motorola_pgtable.h
index 4d94e462bb2b..2ad0f4166841 100644
--- a/arch/m68k/include/asm/motorola_pgtable.h
+++ b/arch/m68k/include/asm/motorola_pgtable.h
@@ -23,7 +23,18 @@
#define _DESCTYPE_MASK 0x003
#define _CACHEMASK040 (~0x060)
-#define _TABLE_MASK (0xfffffe00)
+
+/*
+ * Currently set to the minimum alignment of table pointers (256 bytes).
+ * The hardware only uses the low 4 bits for state:
+ *
+ * 3 - Used
+ * 2 - Write Protected
+ * 0,1 - Descriptor Type
+ *
+ * and has the rest of the bits reserved.
+ */
+#define _TABLE_MASK (0xffffff00)
#define _PAGE_TABLE (_PAGE_SHORT)
#define _PAGE_CHG_MASK (PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_NOCACHE)
diff --git a/arch/m68k/mm/init.c b/arch/m68k/mm/init.c
index 27c453f4fffe..a9b6d26cff8a 100644
--- a/arch/m68k/mm/init.c
+++ b/arch/m68k/mm/init.c
@@ -42,7 +42,6 @@ EXPORT_SYMBOL(empty_zero_page);
#if !defined(CONFIG_SUN3) && !defined(CONFIG_COLDFIRE)
extern void init_pointer_table(unsigned long ptable);
-extern pmd_t *zero_pgtable;
#endif
#ifdef CONFIG_MMU
@@ -135,10 +134,6 @@ static inline void init_pointer_tables(void)
if (pud_present(*pud))
init_pointer_table(pgd_page_vaddr(kernel_pg_dir[i]));
}
-
- /* insert also pointer table that we used to unmap the zero page */
- if (zero_pgtable)
- init_pointer_table((unsigned long)zero_pgtable);
#endif
}
diff --git a/arch/m68k/mm/motorola.c b/arch/m68k/mm/motorola.c
index c888ef46da3e..600f9c1d96f8 100644
--- a/arch/m68k/mm/motorola.c
+++ b/arch/m68k/mm/motorola.c
@@ -174,27 +174,35 @@ extern __initdata unsigned long m68k_init_mapped_size;
extern unsigned long availmem;
+static pte_t *last_pte_table __initdata = NULL;
+
static pte_t * __init kernel_page_table(void)
{
- pte_t *ptablep;
+ pte_t *pte_table = last_pte_table;
- ptablep = (pte_t *)memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
- if (!ptablep)
- panic("%s: Failed to allocate %lu bytes align=%lx\n",
- __func__, PAGE_SIZE, PAGE_SIZE);
+ if (((unsigned long)last_pte_table & ~PAGE_MASK) == 0) {
+ pte_table = (pte_t *)memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
+ if (!pte_table) {
+ panic("%s: Failed to allocate %lu bytes align=%lx\n",
+ __func__, PAGE_SIZE, PAGE_SIZE);
+ }
- clear_page(ptablep);
- mmu_page_ctor(ptablep);
+ clear_page(pte_table);
+ mmu_page_ctor(pte_table);
- return ptablep;
+ last_pte_table = pte_table;
+ }
+
+ last_pte_table += PTRS_PER_PTE;
+
+ return pte_table;
}
-static pmd_t *last_pgtable __initdata = NULL;
-pmd_t *zero_pgtable __initdata = NULL;
+static pmd_t *last_pmd_table __initdata = NULL;
static pmd_t * __init kernel_ptr_table(void)
{
- if (!last_pgtable) {
+ if (!last_pmd_table) {
unsigned long pmd, last;
int i;
@@ -213,25 +221,25 @@ static pmd_t * __init kernel_ptr_table(void)
last = pmd;
}
- last_pgtable = (pmd_t *)last;
+ last_pmd_table = (pmd_t *)last;
#ifdef DEBUG
- printk("kernel_ptr_init: %p\n", last_pgtable);
+ printk("kernel_ptr_init: %p\n", last_pmd_table);
#endif
}
- last_pgtable += PTRS_PER_PMD;
- if (((unsigned long)last_pgtable & ~PAGE_MASK) == 0) {
- last_pgtable = (pmd_t *)memblock_alloc_low(PAGE_SIZE,
+ last_pmd_table += PTRS_PER_PMD;
+ if (((unsigned long)last_pmd_table & ~PAGE_MASK) == 0) {
+ last_pmd_table = (pmd_t *)memblock_alloc_low(PAGE_SIZE,
PAGE_SIZE);
- if (!last_pgtable)
+ if (!last_pmd_table)
panic("%s: Failed to allocate %lu bytes align=%lx\n",
__func__, PAGE_SIZE, PAGE_SIZE);
- clear_page(last_pgtable);
- mmu_page_ctor(last_pgtable);
+ clear_page(last_pmd_table);
+ mmu_page_ctor(last_pmd_table);
}
- return last_pgtable;
+ return last_pmd_table;
}
static void __init map_node(int node)
@@ -294,8 +302,7 @@ static void __init map_node(int node)
#ifdef DEBUG
printk ("[zero map]");
#endif
- zero_pgtable = kernel_ptr_table();
- pte_dir = (pte_t *)zero_pgtable;
+ pte_dir = kernel_page_table();
pmd_set(pmd_dir, pte_dir);
pte_val(*pte_dir++) = 0;