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