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Diffstat (limited to 'arch/x86/mm/dump_pagetables.c')
-rw-r--r-- | arch/x86/mm/dump_pagetables.c | 354 |
1 files changed, 354 insertions, 0 deletions
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c new file mode 100644 index 0000000..6791b83 --- /dev/null +++ b/arch/x86/mm/dump_pagetables.c @@ -0,0 +1,354 @@ +/* + * Debug helper to dump the current kernel pagetables of the system + * so that we can see what the various memory ranges are set to. + * + * (C) Copyright 2008 Intel Corporation + * + * Author: Arjan van de Ven <arjan@linux.intel.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; version 2 + * of the License. + */ + +#include <linux/debugfs.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/seq_file.h> + +#include <asm/pgtable.h> + +/* + * The dumper groups pagetable entries of the same type into one, and for + * that it needs to keep some state when walking, and flush this state + * when a "break" in the continuity is found. + */ +struct pg_state { + int level; + pgprot_t current_prot; + unsigned long start_address; + unsigned long current_address; + const struct addr_marker *marker; +}; + +struct addr_marker { + unsigned long start_address; + const char *name; +}; + +/* Address space markers hints */ +static struct addr_marker address_markers[] = { + { 0, "User Space" }, +#ifdef CONFIG_X86_64 + { 0x8000000000000000UL, "Kernel Space" }, + { 0xffff810000000000UL, "Low Kernel Mapping" }, + { VMALLOC_START, "vmalloc() Area" }, + { VMEMMAP_START, "Vmemmap" }, + { __START_KERNEL_map, "High Kernel Mapping" }, + { MODULES_VADDR, "Modules" }, + { MODULES_END, "End Modules" }, +#else + { PAGE_OFFSET, "Kernel Mapping" }, + { 0/* VMALLOC_START */, "vmalloc() Area" }, + { 0/*VMALLOC_END*/, "vmalloc() End" }, +# ifdef CONFIG_HIGHMEM + { 0/*PKMAP_BASE*/, "Persisent kmap() Area" }, +# endif + { 0/*FIXADDR_START*/, "Fixmap Area" }, +#endif + { -1, NULL } /* End of list */ +}; + +/* Multipliers for offsets within the PTEs */ +#define PTE_LEVEL_MULT (PAGE_SIZE) +#define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT) +#define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT) +#define PGD_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT) + +/* + * Print a readable form of a pgprot_t to the seq_file + */ +static void printk_prot(struct seq_file *m, pgprot_t prot, int level) +{ + pgprotval_t pr = pgprot_val(prot); + static const char * const level_name[] = + { "cr3", "pgd", "pud", "pmd", "pte" }; + + if (!pgprot_val(prot)) { + /* Not present */ + seq_printf(m, " "); + } else { + if (pr & _PAGE_USER) + seq_printf(m, "USR "); + else + seq_printf(m, " "); + if (pr & _PAGE_RW) + seq_printf(m, "RW "); + else + seq_printf(m, "ro "); + if (pr & _PAGE_PWT) + seq_printf(m, "PWT "); + else + seq_printf(m, " "); + if (pr & _PAGE_PCD) + seq_printf(m, "PCD "); + else + seq_printf(m, " "); + + /* Bit 9 has a different meaning on level 3 vs 4 */ + if (level <= 3) { + if (pr & _PAGE_PSE) + seq_printf(m, "PSE "); + else + seq_printf(m, " "); + } else { + if (pr & _PAGE_PAT) + seq_printf(m, "pat "); + else + seq_printf(m, " "); + } + if (pr & _PAGE_GLOBAL) + seq_printf(m, "GLB "); + else + seq_printf(m, " "); + if (pr & _PAGE_NX) + seq_printf(m, "NX "); + else + seq_printf(m, "x "); + } + seq_printf(m, "%s\n", level_name[level]); +} + +/* + * On 64 bits, sign-extend the 48 bit address to 64 bit + */ +static unsigned long normalize_addr(unsigned long u) +{ +#ifdef CONFIG_X86_64 + return (signed long)(u << 16) >> 16; +#else + return u; +#endif +} + +/* + * This function gets called on a break in a continuous series + * of PTE entries; the next one is different so we need to + * print what we collected so far. + */ +static void note_page(struct seq_file *m, struct pg_state *st, + pgprot_t new_prot, int level) +{ + pgprotval_t prot, cur; + static const char units[] = "KMGTPE"; + + /* + * If we have a "break" in the series, we need to flush the state that + * we have now. "break" is either changing perms, levels or + * address space marker. + */ + prot = pgprot_val(new_prot) & ~(PTE_MASK); + cur = pgprot_val(st->current_prot) & ~(PTE_MASK); + + if (!st->level) { + /* First entry */ + st->current_prot = new_prot; + st->level = level; + st->marker = address_markers; + seq_printf(m, "---[ %s ]---\n", st->marker->name); + } else if (prot != cur || level != st->level || + st->current_address >= st->marker[1].start_address) { + const char *unit = units; + unsigned long delta; + + /* + * Now print the actual finished series + */ + seq_printf(m, "0x%p-0x%p ", + (void *)st->start_address, + (void *)st->current_address); + + delta = (st->current_address - st->start_address) >> 10; + while (!(delta & 1023) && unit[1]) { + delta >>= 10; + unit++; + } + seq_printf(m, "%9lu%c ", delta, *unit); + printk_prot(m, st->current_prot, st->level); + + /* + * We print markers for special areas of address space, + * such as the start of vmalloc space etc. + * This helps in the interpretation. + */ + if (st->current_address >= st->marker[1].start_address) { + st->marker++; + seq_printf(m, "---[ %s ]---\n", st->marker->name); + } + + st->start_address = st->current_address; + st->current_prot = new_prot; + st->level = level; + } +} + +static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr, + unsigned long P) +{ + int i; + pte_t *start; + + start = (pte_t *) pmd_page_vaddr(addr); + for (i = 0; i < PTRS_PER_PTE; i++) { + pgprot_t prot = pte_pgprot(*start); + + st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT); + note_page(m, st, prot, 4); + start++; + } +} + +#if PTRS_PER_PMD > 1 + +static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr, + unsigned long P) +{ + int i; + pmd_t *start; + + start = (pmd_t *) pud_page_vaddr(addr); + for (i = 0; i < PTRS_PER_PMD; i++) { + st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT); + if (!pmd_none(*start)) { + pgprotval_t prot = pmd_val(*start) & ~PTE_MASK; + + if (pmd_large(*start) || !pmd_present(*start)) + note_page(m, st, __pgprot(prot), 3); + else + walk_pte_level(m, st, *start, + P + i * PMD_LEVEL_MULT); + } else + note_page(m, st, __pgprot(0), 3); + start++; + } +} + +#else +#define walk_pmd_level(m,s,a,p) walk_pte_level(m,s,__pmd(pud_val(a)),p) +#define pud_large(a) pmd_large(__pmd(pud_val(a))) +#define pud_none(a) pmd_none(__pmd(pud_val(a))) +#endif + +#if PTRS_PER_PUD > 1 + +static void walk_pud_level(struct seq_file *m, struct pg_state *st, pgd_t addr, + unsigned long P) +{ + int i; + pud_t *start; + + start = (pud_t *) pgd_page_vaddr(addr); + + for (i = 0; i < PTRS_PER_PUD; i++) { + st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT); + if (!pud_none(*start)) { + pgprotval_t prot = pud_val(*start) & ~PTE_MASK; + + if (pud_large(*start) || !pud_present(*start)) + note_page(m, st, __pgprot(prot), 2); + else + walk_pmd_level(m, st, *start, + P + i * PUD_LEVEL_MULT); + } else + note_page(m, st, __pgprot(0), 2); + + start++; + } +} + +#else +#define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(pgd_val(a)),p) +#define pgd_large(a) pud_large(__pud(pgd_val(a))) +#define pgd_none(a) pud_none(__pud(pgd_val(a))) +#endif + +static void walk_pgd_level(struct seq_file *m) +{ +#ifdef CONFIG_X86_64 + pgd_t *start = (pgd_t *) &init_level4_pgt; +#else + pgd_t *start = swapper_pg_dir; +#endif + int i; + struct pg_state st; + + memset(&st, 0, sizeof(st)); + + for (i = 0; i < PTRS_PER_PGD; i++) { + st.current_address = normalize_addr(i * PGD_LEVEL_MULT); + if (!pgd_none(*start)) { + pgprotval_t prot = pgd_val(*start) & ~PTE_MASK; + + if (pgd_large(*start) || !pgd_present(*start)) + note_page(m, &st, __pgprot(prot), 1); + else + walk_pud_level(m, &st, *start, + i * PGD_LEVEL_MULT); + } else + note_page(m, &st, __pgprot(0), 1); + + start++; + } + + /* Flush out the last page */ + st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT); + note_page(m, &st, __pgprot(0), 0); +} + +static int ptdump_show(struct seq_file *m, void *v) +{ + walk_pgd_level(m); + return 0; +} + +static int ptdump_open(struct inode *inode, struct file *filp) +{ + return single_open(filp, ptdump_show, NULL); +} + +static const struct file_operations ptdump_fops = { + .open = ptdump_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +int pt_dump_init(void) +{ + struct dentry *pe; + +#ifdef CONFIG_X86_32 + /* Not a compile-time constant on x86-32 */ + address_markers[2].start_address = VMALLOC_START; + address_markers[3].start_address = VMALLOC_END; +# ifdef CONFIG_HIGHMEM + address_markers[4].start_address = PKMAP_BASE; + address_markers[5].start_address = FIXADDR_START; +# else + address_markers[4].start_address = FIXADDR_START; +# endif +#endif + + pe = debugfs_create_file("kernel_page_tables", 0600, NULL, NULL, + &ptdump_fops); + if (!pe) + return -ENOMEM; + + return 0; +} + +__initcall(pt_dump_init); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>"); +MODULE_DESCRIPTION("Kernel debugging helper that dumps pagetables"); |