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-rw-r--r--arch/x86/mm/dump_pagetables.c354
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 000000000000..2c24bea92c66
--- /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,
+};
+
+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");
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-25 08:39:38 +0100