/* * 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 #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; const struct addr_marker *marker; unsigned long lines; bool to_dmesg; }; struct addr_marker { unsigned long start_address; const char *name; unsigned long max_lines; }; /* indices for address_markers; keep sync'd w/ address_markers below */ enum address_markers_idx { USER_SPACE_NR = 0, #ifdef CONFIG_X86_64 KERNEL_SPACE_NR, LOW_KERNEL_NR, VMALLOC_START_NR, VMEMMAP_START_NR, # ifdef CONFIG_X86_ESPFIX64 ESPFIX_START_NR, # endif HIGH_KERNEL_NR, MODULES_VADDR_NR, MODULES_END_NR, #else KERNEL_SPACE_NR, VMALLOC_START_NR, VMALLOC_END_NR, # ifdef CONFIG_HIGHMEM PKMAP_BASE_NR, # endif FIXADDR_START_NR, #endif }; /* 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" }, # ifdef CONFIG_X86_ESPFIX64 { ESPFIX_BASE_ADDR, "ESPfix Area", 16 }, # endif # ifdef CONFIG_EFI { EFI_VA_END, "EFI Runtime Services" }, # endif { __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) #define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \ ({ \ if (to_dmesg) \ printk(KERN_INFO fmt, ##args); \ else \ if (m) \ seq_printf(m, fmt, ##args); \ }) #define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \ ({ \ if (to_dmesg) \ printk(KERN_CONT fmt, ##args); \ else \ if (m) \ seq_printf(m, fmt, ##args); \ }) /* * 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, bool dmsg) { pgprotval_t pr = pgprot_val(prot); static const char * const level_name[] = { "cr3", "pgd", "pud", "pmd", "pte" }; if (!pgprot_val(prot)) { /* Not present */ pt_dump_cont_printf(m, dmsg, " "); } else { if (pr & _PAGE_USER) pt_dump_cont_printf(m, dmsg, "USR "); else pt_dump_cont_printf(m, dmsg, " "); if (pr & _PAGE_RW) pt_dump_cont_printf(m, dmsg, "RW "); else pt_dump_cont_printf(m, dmsg, "ro "); if (pr & _PAGE_PWT) pt_dump_cont_printf(m, dmsg, "PWT "); else pt_dump_cont_printf(m, dmsg, " "); if (pr & _PAGE_PCD) pt_dump_cont_printf(m, dmsg, "PCD "); else pt_dump_cont_printf(m, dmsg, " "); /* Bit 7 has a different meaning on level 3 vs 4 */ if (level <= 3 && pr & _PAGE_PSE) pt_dump_cont_printf(m, dmsg, "PSE "); else pt_dump_cont_printf(m, dmsg, " "); if ((level == 4 && pr & _PAGE_PAT) || ((level == 3 || level == 2) && pr & _PAGE_PAT_LARGE)) pt_dump_cont_printf(m, dmsg, "pat "); else pt_dump_cont_printf(m, dmsg, " "); if (pr & _PAGE_GLOBAL) pt_dump_cont_printf(m, dmsg, "GLB "); else pt_dump_cont_printf(m, dmsg, " "); if (pr & _PAGE_NX) pt_dump_cont_printf(m, dmsg, "NX "); else pt_dump_cont_printf(m, dmsg, "x "); } pt_dump_cont_printf(m, dmsg, "%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[] = "BKMGTPE"; /* * 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; st->lines = 0; pt_dump_seq_printf(m, st->to_dmesg, "---[ %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; int width = sizeof(unsigned long) * 2; /* * Now print the actual finished series */ if (!st->marker->max_lines || st->lines < st->marker->max_lines) { pt_dump_seq_printf(m, st->to_dmesg, "0x%0*lx-0x%0*lx ", width, st->start_address, width, st->current_address); delta = st->current_address - st->start_address; while (!(delta & 1023) && unit[1]) { delta >>= 10; unit++; } pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ", delta, *unit); printk_prot(m, st->current_prot, st->level, st->to_dmesg); } st->lines++; /* * 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) { if (st->marker->max_lines && st->lines > st->marker->max_lines) { unsigned long nskip = st->lines - st->marker->max_lines; pt_dump_seq_printf(m, st->to_dmesg, "... %lu entr%s skipped ... \n", nskip, nskip == 1 ? "y" : "ies"); } st->marker++; st->lines = 0; pt_dump_seq_printf(m, st->to_dmesg, "---[ %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 void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd) { #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 = {}; if (pgd) { start = pgd; st.to_dmesg = true; } 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) { ptdump_walk_pgd_level(m, NULL); 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[VMALLOC_START_NR].start_address = VMALLOC_START; address_markers[VMALLOC_END_NR].start_address = VMALLOC_END; # ifdef CONFIG_HIGHMEM address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE; # endif address_markers[FIXADDR_START_NR].start_address = FIXADDR_START; #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 "); MODULE_DESCRIPTION("Kernel debugging helper that dumps pagetables");