/* * 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 * * 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 #include #include #include /* * 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; int printed_vmalloc; int printed_modules; int printed_vmemmap; int printed_highmap; }; /* Multipliers for offsets within the PTEs */ #define LEVEL_4_MULT (PAGE_SIZE) #define LEVEL_3_MULT (512UL * LEVEL_4_MULT) #define LEVEL_2_MULT (512UL * LEVEL_3_MULT) #define LEVEL_1_MULT (512UL * LEVEL_2_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) { unsigned long pr = pgprot_val(prot); 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 "); } /* * Sign-extend the 48 bit address to 64 bit */ static unsigned long sign_extend(unsigned long u) { if (u>>47) u = u | (0xffffUL << 48); return u; } /* * 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) { unsigned long prot, cur; /* * If we have a "break" in the series, we need to flush the state that * we have now. "break" is either changing perms or a different level. */ prot = pgprot_val(new_prot) & ~(PTE_MASK); cur = pgprot_val(st->current_prot) & ~(PTE_MASK); if ((prot != cur || level != st->level) && st->current_address != st->start_address) { char unit = 'K'; unsigned long delta; /* * We print markers for special areas of address space, * such as the start of vmalloc space etc. * This helps in the interpretation. */ if (!st->printed_vmalloc && st->start_address >= VMALLOC_START) { seq_printf(m, "---[ VMALLOC SPACE ]---\n"); st->printed_vmalloc = 1; } if (!st->printed_modules && st->start_address >= MODULES_VADDR) { seq_printf(m, "---[ MODULES SPACE ]---\n"); st->printed_modules = 1; } if (st->printed_modules < 2 && st->start_address >= MODULES_END) { seq_printf(m, "---[ END MODULES SPACE ]---\n"); st->printed_modules = 2; } if (!st->printed_vmemmap && st->start_address >= VMEMMAP_START) { seq_printf(m, "---[ VMMEMMAP SPACE ]---\n"); st->printed_vmemmap = 1; } if (!st->printed_highmap && st->start_address >= __START_KERNEL_map) { seq_printf(m, "---[ HIGH KERNEL MAPPING ]---\n"); st->printed_highmap = 1; } /* * Now print the actual finished series */ seq_printf(m, "[ %016lx - %016lx ", st->start_address, st->current_address); delta = (st->current_address - st->start_address) >> 10; if ((delta & 1023) == 0) { delta = delta >> 10; unit = 'M'; } if (pgprot_val(st->current_prot)) { seq_printf(m, "Size %9lu%cb ", delta, unit); printk_prot(m, st->current_prot, st->level); seq_printf(m, "L%i]\n", st->level); } else { /* don't print protections on non-present memory */ seq_printf(m, "%14lu%cb", delta, unit); seq_printf(m, " L%i]\n", st->level); } st->start_address = st->current_address; st->current_prot = new_prot; st->level = level; }; } static void walk_level_4(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 = sign_extend(P + i * LEVEL_4_MULT); note_page(m, st, prot, 4); start++; } } static void walk_level_3(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 = sign_extend(P + i * LEVEL_3_MULT); if (!pmd_none(*start)) { unsigned long prot; prot = pmd_val(*start) & ~(PTE_MASK); /* Deal with 2Mb pages */ if (pmd_large(*start)) note_page(m, st, __pgprot(prot), 3); else walk_level_4(m, st, *start, P + i * LEVEL_3_MULT); } else note_page(m, st, __pgprot(0), 3); start++; } } static void walk_level_2(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++) { if (!pud_none(*start)) { unsigned long prot; prot = pud_val(*start) & ~(PTE_MASK); /* Deal with 1Gb pages */ if (pud_large(*start)) note_page(m, st, __pgprot(prot), 2); else walk_level_3(m, st, *start, P + i * LEVEL_2_MULT); } else note_page(m, st, __pgprot(0), 2); start++; } } static void walk_level_1(struct seq_file *m) { pgd_t *start = (pgd_t *) &init_level4_pgt; int i; struct pg_state st; memset(&st, 0, sizeof(st)); st.level = 1; for (i = 0; i < PTRS_PER_PGD; i++) { if (!pgd_none(*start)) walk_level_2(m, &st, *start, i * LEVEL_1_MULT); else note_page(m, &st, __pgprot(0), 1); start++; } } static int ptdump_show(struct seq_file *m, void *v) { seq_puts(m, "Kernel pagetable dump\n"); walk_level_1(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; 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 "); MODULE_DESCRIPTION("Kernel debugging helper that dumps pagetables");