arm64: add support to dump the kernel page tables

In a similar manner to arm, it's useful to be able to dump the page
tables to verify permissions and memory types. Add a debugfs file
to check the page tables.

Acked-by: Steve Capper <steve.capper@linaro.org>
Tested-by: Steve Capper <steve.capper@linaro.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
[will: s/BUFFERABLE/NORMAL-NC/]
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 332 insertions, 0 deletions

diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
new file mode 100644
index 000000000000..bf69601be546
--- /dev/null
+++ b/arch/arm64/mm/dump.c
@@ -0,0 +1,332 @@
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ * Debug helper to dump the current kernel pagetables of the system
+ * so that we can see what the various memory ranges are set to.
+ *
+ * Derived from x86 and arm implementation:
+ * (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/fs.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/seq_file.h>
+
+#include <asm/fixmap.h>
+#include <asm/pgtable.h>
+
+#define LOWEST_ADDR     (UL(0xffffffffffffffff) << VA_BITS)
+
+struct addr_marker {
+        unsigned long start_address;
+        const char *name;
+};
+
+enum address_markers_idx {
+        VMALLOC_START_NR = 0,
+        VMALLOC_END_NR,
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+        VMEMMAP_START_NR,
+        VMEMMAP_END_NR,
+#endif
+        PCI_START_NR,
+        PCI_END_NR,
+        FIXADDR_START_NR,
+        FIXADDR_END_NR,
+        MODULES_START_NR,
+        MODUELS_END_NR,
+        KERNEL_SPACE_NR,
+};
+
+static struct addr_marker address_markers[] = {
+        { VMALLOC_START,        "vmalloc() Area" },
+        { VMALLOC_END,          "vmalloc() End" },
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+        { 0,                    "vmemmap start" },
+        { 0,                    "vmemmap end" },
+#endif
+        { (unsigned long) PCI_IOBASE,           "PCI I/O start" },
+        { (unsigned long) PCI_IOBASE + SZ_16M,  "PCI I/O end" },
+        { FIXADDR_START,        "Fixmap start" },
+        { FIXADDR_TOP,          "Fixmap end" },
+        { MODULES_VADDR,        "Modules start" },
+        { MODULES_END,          "Modules end" },
+        { PAGE_OFFSET,          "Kernel Mapping" },
+        { -1,                   NULL },
+};
+
+struct pg_state {
+        struct seq_file *seq;
+        const struct addr_marker *marker;
+        unsigned long start_address;
+        unsigned level;
+        u64 current_prot;
+};
+
+struct prot_bits {
+        u64             mask;
+        u64             val;
+        const char      *set;
+        const char      *clear;
+};
+
+static const struct prot_bits pte_bits[] = {
+        {
+                .mask   = PTE_USER,
+                .val    = PTE_USER,
+                .set    = "USR",
+                .clear  = "   ",
+        }, {
+                .mask   = PTE_RDONLY,
+                .val    = PTE_RDONLY,
+                .set    = "ro",
+                .clear  = "RW",
+        }, {
+                .mask   = PTE_PXN,
+                .val    = PTE_PXN,
+                .set    = "NX",
+                .clear  = "x ",
+        }, {
+                .mask   = PTE_SHARED,
+                .val    = PTE_SHARED,
+                .set    = "SHD",
+                .clear  = "   ",
+        }, {
+                .mask   = PTE_AF,
+                .val    = PTE_AF,
+                .set    = "AF",
+                .clear  = "  ",
+        }, {
+                .mask   = PTE_NG,
+                .val    = PTE_NG,
+                .set    = "NG",
+                .clear  = "  ",
+        }, {
+                .mask   = PTE_UXN,
+                .val    = PTE_UXN,
+                .set    = "UXN",
+        }, {
+                .mask   = PTE_ATTRINDX_MASK,
+                .val    = PTE_ATTRINDX(MT_DEVICE_nGnRnE),
+                .set    = "DEVICE/nGnRnE",
+        }, {
+                .mask   = PTE_ATTRINDX_MASK,
+                .val    = PTE_ATTRINDX(MT_DEVICE_nGnRE),
+                .set    = "DEVICE/nGnRE",
+        }, {
+                .mask   = PTE_ATTRINDX_MASK,
+                .val    = PTE_ATTRINDX(MT_DEVICE_GRE),
+                .set    = "DEVICE/GRE",
+        }, {
+                .mask   = PTE_ATTRINDX_MASK,
+                .val    = PTE_ATTRINDX(MT_NORMAL_NC),
+                .set    = "MEM/NORMAL-NC",
+        }, {
+                .mask   = PTE_ATTRINDX_MASK,
+                .val    = PTE_ATTRINDX(MT_NORMAL),
+                .set    = "MEM/NORMAL",
+        }
+};
+
+struct pg_level {
+        const struct prot_bits *bits;
+        size_t num;
+        u64 mask;
+};
+
+static struct pg_level pg_level[] = {
+        {
+        }, { /* pgd */
+                .bits   = pte_bits,
+                .num    = ARRAY_SIZE(pte_bits),
+        }, { /* pud */
+                .bits   = pte_bits,
+                .num    = ARRAY_SIZE(pte_bits),
+        }, { /* pmd */
+                .bits   = pte_bits,
+                .num    = ARRAY_SIZE(pte_bits),
+        }, { /* pte */
+                .bits   = pte_bits,
+                .num    = ARRAY_SIZE(pte_bits),
+        },
+};
+
+static void dump_prot(struct pg_state *st, const struct prot_bits *bits,
+                        size_t num)
+{
+        unsigned i;
+
+        for (i = 0; i < num; i++, bits++) {
+                const char *s;
+
+                if ((st->current_prot & bits->mask) == bits->val)
+                        s = bits->set;
+                else
+                        s = bits->clear;
+
+                if (s)
+                        seq_printf(st->seq, " %s", s);
+        }
+}
+
+static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
+                                u64 val)
+{
+        static const char units[] = "KMGTPE";
+        u64 prot = val & pg_level[level].mask;
+
+        if (addr < LOWEST_ADDR)
+                return;
+
+        if (!st->level) {
+                st->level = level;
+                st->current_prot = prot;
+                st->start_address = addr;
+                seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
+        } else if (prot != st->current_prot || level != st->level ||
+                   addr >= st->marker[1].start_address) {
+                const char *unit = units;
+                unsigned long delta;
+
+                if (st->current_prot) {
+                        seq_printf(st->seq, "0x%16lx-0x%16lx   ",
+                                   st->start_address, addr);
+
+                        delta = (addr - st->start_address) >> 10;
+                        while (!(delta & 1023) && unit[1]) {
+                                delta >>= 10;
+                                unit++;
+                        }
+                        seq_printf(st->seq, "%9lu%c", delta, *unit);
+                        if (pg_level[st->level].bits)
+                                dump_prot(st, pg_level[st->level].bits,
+                                          pg_level[st->level].num);
+                        seq_puts(st->seq, "\n");
+                }
+
+                if (addr >= st->marker[1].start_address) {
+                        st->marker++;
+                        seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
+                }
+
+                st->start_address = addr;
+                st->current_prot = prot;
+                st->level = level;
+        }
+
+        if (addr >= st->marker[1].start_address) {
+                st->marker++;
+                seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
+        }
+
+}
+
+static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start)
+{
+        pte_t *pte = pte_offset_kernel(pmd, 0);
+        unsigned long addr;
+        unsigned i;
+
+        for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
+                addr = start + i * PAGE_SIZE;
+                note_page(st, addr, 4, pte_val(*pte));
+        }
+}
+
+static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
+{
+        pmd_t *pmd = pmd_offset(pud, 0);
+        unsigned long addr;
+        unsigned i;
+
+        for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
+                addr = start + i * PMD_SIZE;
+                if (pmd_none(*pmd) || pmd_sect(*pmd) || pmd_bad(*pmd))
+                        note_page(st, addr, 3, pmd_val(*pmd));
+                else
+                        walk_pte(st, pmd, addr);
+        }
+}
+
+static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
+{
+        pud_t *pud = pud_offset(pgd, 0);
+        unsigned long addr;
+        unsigned i;
+
+        for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
+                addr = start + i * PUD_SIZE;
+                if (pud_none(*pud) || pud_sect(*pud) || pud_bad(*pud))
+                        note_page(st, addr, 2, pud_val(*pud));
+                else
+                        walk_pmd(st, pud, addr);
+        }
+}
+
+static void walk_pgd(struct pg_state *st, struct mm_struct *mm, unsigned long start)
+{
+        pgd_t *pgd = pgd_offset(mm, 0);
+        unsigned i;
+        unsigned long addr;
+
+        for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
+                addr = start + i * PGDIR_SIZE;
+                if (pgd_none(*pgd) || pgd_bad(*pgd))
+                        note_page(st, addr, 1, pgd_val(*pgd));
+                else
+                        walk_pud(st, pgd, addr);
+        }
+}
+
+static int ptdump_show(struct seq_file *m, void *v)
+{
+        struct pg_state st = {
+                .seq = m,
+                .marker = address_markers,
+        };
+
+        walk_pgd(&st, &init_mm, LOWEST_ADDR);
+
+        note_page(&st, 0, 0, 0);
+        return 0;
+}
+
+static int ptdump_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, ptdump_show, NULL);
+}
+
+static const struct file_operations ptdump_fops = {
+        .open           = ptdump_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+};
+
+static int ptdump_init(void)
+{
+        struct dentry *pe;
+        unsigned i, j;
+
+        for (i = 0; i < ARRAY_SIZE(pg_level); i++)
+                if (pg_level[i].bits)
+                        for (j = 0; j < pg_level[i].num; j++)
+                                pg_level[i].mask |= pg_level[i].bits[j].mask;
+
+        address_markers[VMEMMAP_START_NR].start_address =
+                                (unsigned long)virt_to_page(PAGE_OFFSET);
+        address_markers[VMEMMAP_END_NR].start_address =
+                                (unsigned long)virt_to_page(high_memory);
+
+        pe = debugfs_create_file("kernel_page_tables", 0400, NULL, NULL,
+                                 &ptdump_fops);
+        return pe ? 0 : -ENOMEM;
+}
+device_initcall(ptdump_init);