diff options
Diffstat (limited to 'arch/arm/mm/dump.c')
| -rw-r--r-- | arch/arm/mm/dump.c | 468 |
1 files changed, 468 insertions, 0 deletions
diff --git a/arch/arm/mm/dump.c b/arch/arm/mm/dump.c new file mode 100644 index 000000000..9b9023a92 --- /dev/null +++ b/arch/arm/mm/dump.c @@ -0,0 +1,468 @@ +// 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/memory.h> +#include <asm/ptdump.h> + +static struct addr_marker address_markers[] = { + { MODULES_VADDR, "Modules" }, + { PAGE_OFFSET, "Kernel Mapping" }, + { 0, "vmalloc() Area" }, + { VMALLOC_END, "vmalloc() End" }, + { 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 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 */ + .bits = section_bits, + .num = ARRAY_SIZE(section_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) + 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", delta, *unit); + 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 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]; + } + + address_markers[2].start_address = VMALLOC_START; +} + +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 ptdump_init(void) +{ + ptdump_initialize(); + ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables"); + return 0; +} +__initcall(ptdump_init); |