| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * 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 implementation: |
| * (C) Copyright 2008 Intel Corporation |
| * |
| * Author: Arjan van de Ven <arjan@linux.intel.com> |
| */ |
| #include <linux/debugfs.h> |
| #include <linux/fs.h> |
| #include <linux/mm.h> |
| #include <linux/seq_file.h> |
| |
| #include <asm/domain.h> |
| #include <asm/fixmap.h> |
| #include <asm/page.h> |
| #include <asm/ptdump.h> |
| |
| static struct addr_marker address_markers[] = { |
| #ifdef CONFIG_KASAN |
| { KASAN_SHADOW_START, "Kasan shadow start"}, |
| { KASAN_SHADOW_END, "Kasan shadow end"}, |
| #endif |
| { MODULES_VADDR, "Modules" }, |
| { PAGE_OFFSET, "Kernel Mapping" }, |
| { 0, "vmalloc() Area" }, |
| { FDT_FIXED_BASE, "FDT Area" }, |
| { FIXADDR_START, "Fixmap Area" }, |
| { VECTORS_BASE, "Vectors" }, |
| { VECTORS_BASE + PAGE_SIZE * 2, "Vectors End" }, |
| { -1, NULL }, |
| }; |
| |
| #define pt_dump_seq_printf(m, fmt, args...) \ |
| ({ \ |
| if (m) \ |
| seq_printf(m, fmt, ##args); \ |
| }) |
| |
| #define pt_dump_seq_puts(m, fmt) \ |
| ({ \ |
| if (m) \ |
| seq_printf(m, fmt); \ |
| }) |
| |
| struct pg_state { |
| struct seq_file *seq; |
| const struct addr_marker *marker; |
| unsigned long start_address; |
| unsigned level; |
| u64 current_prot; |
| bool check_wx; |
| unsigned long wx_pages; |
| const char *current_domain; |
| }; |
| |
| struct prot_bits { |
| u64 mask; |
| u64 val; |
| const char *set; |
| const char *clear; |
| bool ro_bit; |
| bool nx_bit; |
| }; |
| |
| static const struct prot_bits pte_bits[] = { |
| { |
| .mask = L_PTE_USER, |
| .val = L_PTE_USER, |
| .set = "USR", |
| .clear = " ", |
| }, { |
| .mask = L_PTE_RDONLY, |
| .val = L_PTE_RDONLY, |
| .set = "ro", |
| .clear = "RW", |
| .ro_bit = true, |
| }, { |
| .mask = L_PTE_XN, |
| .val = L_PTE_XN, |
| .set = "NX", |
| .clear = "x ", |
| .nx_bit = true, |
| }, { |
| .mask = L_PTE_SHARED, |
| .val = L_PTE_SHARED, |
| .set = "SHD", |
| .clear = " ", |
| }, { |
| .mask = L_PTE_MT_MASK, |
| .val = L_PTE_MT_UNCACHED, |
| .set = "SO/UNCACHED", |
| }, { |
| .mask = L_PTE_MT_MASK, |
| .val = L_PTE_MT_BUFFERABLE, |
| .set = "MEM/BUFFERABLE/WC", |
| }, { |
| .mask = L_PTE_MT_MASK, |
| .val = L_PTE_MT_WRITETHROUGH, |
| .set = "MEM/CACHED/WT", |
| }, { |
| .mask = L_PTE_MT_MASK, |
| .val = L_PTE_MT_WRITEBACK, |
| .set = "MEM/CACHED/WBRA", |
| #ifndef CONFIG_ARM_LPAE |
| }, { |
| .mask = L_PTE_MT_MASK, |
| .val = L_PTE_MT_MINICACHE, |
| .set = "MEM/MINICACHE", |
| #endif |
| }, { |
| .mask = L_PTE_MT_MASK, |
| .val = L_PTE_MT_WRITEALLOC, |
| .set = "MEM/CACHED/WBWA", |
| }, { |
| .mask = L_PTE_MT_MASK, |
| .val = L_PTE_MT_DEV_SHARED, |
| .set = "DEV/SHARED", |
| #ifndef CONFIG_ARM_LPAE |
| }, { |
| .mask = L_PTE_MT_MASK, |
| .val = L_PTE_MT_DEV_NONSHARED, |
| .set = "DEV/NONSHARED", |
| #endif |
| }, { |
| .mask = L_PTE_MT_MASK, |
| .val = L_PTE_MT_DEV_WC, |
| .set = "DEV/WC", |
| }, { |
| .mask = L_PTE_MT_MASK, |
| .val = L_PTE_MT_DEV_CACHED, |
| .set = "DEV/CACHED", |
| }, |
| }; |
| |
| static const struct prot_bits section_bits[] = { |
| #ifdef CONFIG_ARM_LPAE |
| { |
| .mask = PMD_SECT_USER, |
| .val = PMD_SECT_USER, |
| .set = "USR", |
| }, { |
| .mask = L_PMD_SECT_RDONLY | PMD_SECT_AP2, |
| .val = L_PMD_SECT_RDONLY | PMD_SECT_AP2, |
| .set = "ro", |
| .clear = "RW", |
| .ro_bit = true, |
| #elif __LINUX_ARM_ARCH__ >= 6 |
| { |
| .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
| .val = PMD_SECT_APX | PMD_SECT_AP_WRITE, |
| .set = " ro", |
| .ro_bit = true, |
| }, { |
| .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
| .val = PMD_SECT_AP_WRITE, |
| .set = " RW", |
| }, { |
| .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
| .val = PMD_SECT_AP_READ, |
| .set = "USR ro", |
| }, { |
| .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
| .val = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
| .set = "USR RW", |
| #else /* ARMv4/ARMv5 */ |
| /* These are approximate */ |
| { |
| .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
| .val = 0, |
| .set = " ro", |
| .ro_bit = true, |
| }, { |
| .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
| .val = PMD_SECT_AP_WRITE, |
| .set = " RW", |
| }, { |
| .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
| .val = PMD_SECT_AP_READ, |
| .set = "USR ro", |
| }, { |
| .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
| .val = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, |
| .set = "USR RW", |
| #endif |
| }, { |
| .mask = PMD_SECT_XN, |
| .val = PMD_SECT_XN, |
| .set = "NX", |
| .clear = "x ", |
| .nx_bit = true, |
| }, { |
| .mask = PMD_SECT_S, |
| .val = PMD_SECT_S, |
| .set = "SHD", |
| .clear = " ", |
| }, |
| }; |
| |
| struct pg_level { |
| const char *name; |
| const struct prot_bits *bits; |
| size_t num; |
| u64 mask; |
| const struct prot_bits *ro_bit; |
| const struct prot_bits *nx_bit; |
| }; |
| |
| static struct pg_level pg_level[] = { |
| { |
| }, { /* pgd */ |
| }, { /* p4d */ |
| }, { /* pud */ |
| }, { /* pmd */ |
| .name = (CONFIG_PGTABLE_LEVELS > 2) ? "PMD" : "PGD", |
| .bits = section_bits, |
| .num = ARRAY_SIZE(section_bits), |
| }, { /* pte */ |
| .name = "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) |
| pt_dump_seq_printf(st->seq, " %s", s); |
| } |
| } |
| |
| static void note_prot_wx(struct pg_state *st, unsigned long addr) |
| { |
| if (!st->check_wx) |
| return; |
| if ((st->current_prot & pg_level[st->level].ro_bit->mask) == |
| pg_level[st->level].ro_bit->val) |
| return; |
| if ((st->current_prot & pg_level[st->level].nx_bit->mask) == |
| pg_level[st->level].nx_bit->val) |
| return; |
| |
| WARN_ONCE(1, "arm/mm: Found insecure W+X mapping at address %pS\n", |
| (void *)st->start_address); |
| |
| st->wx_pages += (addr - st->start_address) / PAGE_SIZE; |
| } |
| |
| static void note_page(struct pg_state *st, unsigned long addr, |
| unsigned int level, u64 val, const char *domain) |
| { |
| static const char units[] = "KMGTPE"; |
| u64 prot = val & pg_level[level].mask; |
| |
| if (!st->level) { |
| st->level = level; |
| st->current_prot = prot; |
| st->current_domain = domain; |
| pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); |
| } else if (prot != st->current_prot || level != st->level || |
| domain != st->current_domain || |
| addr >= st->marker[1].start_address) { |
| const char *unit = units; |
| unsigned long delta; |
| |
| if (st->current_prot) { |
| note_prot_wx(st, addr); |
| pt_dump_seq_printf(st->seq, "0x%08lx-0x%08lx ", |
| st->start_address, addr); |
| |
| delta = (addr - st->start_address) >> 10; |
| while (!(delta & 1023) && unit[1]) { |
| delta >>= 10; |
| unit++; |
| } |
| pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit, |
| pg_level[st->level].name); |
| if (st->current_domain) |
| pt_dump_seq_printf(st->seq, " %s", |
| st->current_domain); |
| if (pg_level[st->level].bits) |
| dump_prot(st, pg_level[st->level].bits, pg_level[st->level].num); |
| pt_dump_seq_printf(st->seq, "\n"); |
| } |
| |
| if (addr >= st->marker[1].start_address) { |
| st->marker++; |
| pt_dump_seq_printf(st->seq, "---[ %s ]---\n", |
| st->marker->name); |
| } |
| st->start_address = addr; |
| st->current_prot = prot; |
| st->current_domain = domain; |
| st->level = level; |
| } |
| } |
| |
| static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start, |
| const char *domain) |
| { |
| 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, 5, pte_val(*pte), domain); |
| } |
| } |
| |
| static const char *get_domain_name(pmd_t *pmd) |
| { |
| #ifndef CONFIG_ARM_LPAE |
| switch (pmd_val(*pmd) & PMD_DOMAIN_MASK) { |
| case PMD_DOMAIN(DOMAIN_KERNEL): |
| return "KERNEL "; |
| case PMD_DOMAIN(DOMAIN_USER): |
| return "USER "; |
| case PMD_DOMAIN(DOMAIN_IO): |
| return "IO "; |
| case PMD_DOMAIN(DOMAIN_VECTORS): |
| return "VECTORS"; |
| default: |
| return "unknown"; |
| } |
| #endif |
| return NULL; |
| } |
| |
| 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; |
| const char *domain; |
| |
| for (i = 0; i < PTRS_PER_PMD; i++, pmd++) { |
| addr = start + i * PMD_SIZE; |
| domain = get_domain_name(pmd); |
| if (pmd_none(*pmd) || pmd_large(*pmd) || !pmd_present(*pmd)) |
| note_page(st, addr, 4, pmd_val(*pmd), domain); |
| else |
| walk_pte(st, pmd, addr, domain); |
| |
| if (SECTION_SIZE < PMD_SIZE && pmd_large(pmd[1])) { |
| addr += SECTION_SIZE; |
| pmd++; |
| domain = get_domain_name(pmd); |
| note_page(st, addr, 4, pmd_val(*pmd), domain); |
| } |
| } |
| } |
| |
| static void walk_pud(struct pg_state *st, p4d_t *p4d, unsigned long start) |
| { |
| pud_t *pud = pud_offset(p4d, 0); |
| unsigned long addr; |
| unsigned i; |
| |
| for (i = 0; i < PTRS_PER_PUD; i++, pud++) { |
| addr = start + i * PUD_SIZE; |
| if (!pud_none(*pud)) { |
| walk_pmd(st, pud, addr); |
| } else { |
| note_page(st, addr, 3, pud_val(*pud), NULL); |
| } |
| } |
| } |
| |
| static void walk_p4d(struct pg_state *st, pgd_t *pgd, unsigned long start) |
| { |
| p4d_t *p4d = p4d_offset(pgd, 0); |
| unsigned long addr; |
| unsigned i; |
| |
| for (i = 0; i < PTRS_PER_P4D; i++, p4d++) { |
| addr = start + i * P4D_SIZE; |
| if (!p4d_none(*p4d)) { |
| walk_pud(st, p4d, addr); |
| } else { |
| note_page(st, addr, 2, p4d_val(*p4d), NULL); |
| } |
| } |
| } |
| |
| static void walk_pgd(struct pg_state *st, struct mm_struct *mm, |
| unsigned long start) |
| { |
| pgd_t *pgd = pgd_offset(mm, 0UL); |
| unsigned i; |
| unsigned long addr; |
| |
| for (i = 0; i < PTRS_PER_PGD; i++, pgd++) { |
| addr = start + i * PGDIR_SIZE; |
| if (!pgd_none(*pgd)) { |
| walk_p4d(st, pgd, addr); |
| } else { |
| note_page(st, addr, 1, pgd_val(*pgd), NULL); |
| } |
| } |
| } |
| |
| void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info) |
| { |
| struct pg_state st = { |
| .seq = m, |
| .marker = info->markers, |
| .check_wx = false, |
| }; |
| |
| walk_pgd(&st, info->mm, info->base_addr); |
| note_page(&st, 0, 0, 0, NULL); |
| } |
| |
| static void __init ptdump_initialize(void) |
| { |
| 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; |
| if (pg_level[i].bits[j].ro_bit) |
| pg_level[i].ro_bit = &pg_level[i].bits[j]; |
| if (pg_level[i].bits[j].nx_bit) |
| pg_level[i].nx_bit = &pg_level[i].bits[j]; |
| } |
| #ifdef CONFIG_KASAN |
| address_markers[4].start_address = VMALLOC_START; |
| #else |
| address_markers[2].start_address = VMALLOC_START; |
| #endif |
| } |
| |
| static struct ptdump_info kernel_ptdump_info = { |
| .mm = &init_mm, |
| .markers = address_markers, |
| .base_addr = 0, |
| }; |
| |
| void ptdump_check_wx(void) |
| { |
| struct pg_state st = { |
| .seq = NULL, |
| .marker = (struct addr_marker[]) { |
| { 0, NULL}, |
| { -1, NULL}, |
| }, |
| .check_wx = true, |
| }; |
| |
| walk_pgd(&st, &init_mm, 0); |
| note_page(&st, 0, 0, 0, NULL); |
| if (st.wx_pages) |
| pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", |
| st.wx_pages); |
| else |
| pr_info("Checked W+X mappings: passed, no W+X pages found\n"); |
| } |
| |
| static int __init ptdump_init(void) |
| { |
| ptdump_initialize(); |
| ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables"); |
| return 0; |
| } |
| __initcall(ptdump_init); |