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..6791b8334bc6
--- /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,
+};
+
+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");