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-rw-r--r--arch/x86/Kconfig.debug12
-rw-r--r--arch/x86/mm/Makefile1
-rw-r--r--arch/x86/mm/dump_pagetables.c301
3 files changed, 314 insertions, 0 deletions
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 702eb39901ca..cb7002eca887 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -54,6 +54,18 @@ config DEBUG_PER_CPU_MAPS
Say N if unsure.
+config X86_PTDUMP
+ bool "Export kernel pagetable layout to userspace via debugfs"
+ depends on X86_64
+ select DEBUG_FS
+ help
+ Say Y here if you want to show the kernel pagetable layout in a
+ debugfs file. This information is only useful for kernel developers
+ who are working in architecture specific areas of the kernel.
+ It is probably not a good idea to enable this feature in a production
+ kernel.
+ If in doubt, say "N"
+
config DEBUG_RODATA
bool "Write protect kernel read-only data structures"
default y
diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index 8e81660604bc..28632f42ca66 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -12,4 +12,5 @@ else
obj-$(CONFIG_NUMA) += numa_64.o
obj-$(CONFIG_K8_NUMA) += k8topology_64.o
obj-$(CONFIG_ACPI_NUMA) += srat_64.o
+obj-$(CONFIG_X86_PTDUMP) += dump_pagetables.o
endif
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
new file mode 100644
index 000000000000..5e7f6430c27e
--- /dev/null
+++ b/arch/x86/mm/dump_pagetables.c
@@ -0,0 +1,301 @@
+/*
+ * 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/module.h>
+#include <linux/seq_file.h>
+#include <linux/debugfs.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;
+ 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 <arjan@linux.intel.com>");
+MODULE_DESCRIPTION("Kernel debugging helper that dumps pagetables");
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-02 06:15:23 +0000