/* * 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" }, { PAGE_OFFSET, "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_FLAGS_MASK; cur = pgprot_val(st->current_prot) & PTE_FLAGS_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_FLAGS_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_FLAGS_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_FLAGS_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, }; static 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");