/* * 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 * * 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 #include #include #include #include #include #include #include /* * 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; pgprotval_t effective_prot; unsigned long start_address; unsigned long current_address; const struct addr_marker *marker; unsigned long lines; bool to_dmesg; bool check_wx; unsigned long wx_pages; }; struct addr_marker { unsigned long start_address; const char *name; unsigned long max_lines; }; /* Address space markers hints */ #ifdef CONFIG_X86_64 enum address_markers_idx { USER_SPACE_NR = 0, KERNEL_SPACE_NR, LOW_KERNEL_NR, #if defined(CONFIG_MODIFY_LDT_SYSCALL) && defined(CONFIG_X86_5LEVEL) LDT_NR, #endif VMALLOC_START_NR, VMEMMAP_START_NR, #ifdef CONFIG_KASAN KASAN_SHADOW_START_NR, KASAN_SHADOW_END_NR, #endif CPU_ENTRY_AREA_NR, #if defined(CONFIG_MODIFY_LDT_SYSCALL) && !defined(CONFIG_X86_5LEVEL) LDT_NR, #endif #ifdef CONFIG_X86_ESPFIX64 ESPFIX_START_NR, #endif #ifdef CONFIG_EFI EFI_END_NR, #endif HIGH_KERNEL_NR, MODULES_VADDR_NR, MODULES_END_NR, FIXADDR_START_NR, END_OF_SPACE_NR, }; static struct addr_marker address_markers[] = { [USER_SPACE_NR] = { 0, "User Space" }, [KERNEL_SPACE_NR] = { (1UL << 63), "Kernel Space" }, [LOW_KERNEL_NR] = { 0UL, "Low Kernel Mapping" }, [VMALLOC_START_NR] = { 0UL, "vmalloc() Area" }, [VMEMMAP_START_NR] = { 0UL, "Vmemmap" }, #ifdef CONFIG_KASAN /* * These fields get initialized with the (dynamic) * KASAN_SHADOW_{START,END} values in pt_dump_init(). */ [KASAN_SHADOW_START_NR] = { 0UL, "KASAN shadow" }, [KASAN_SHADOW_END_NR] = { 0UL, "KASAN shadow end" }, #endif #ifdef CONFIG_MODIFY_LDT_SYSCALL [LDT_NR] = { 0UL, "LDT remap" }, #endif [CPU_ENTRY_AREA_NR] = { CPU_ENTRY_AREA_BASE,"CPU entry Area" }, #ifdef CONFIG_X86_ESPFIX64 [ESPFIX_START_NR] = { ESPFIX_BASE_ADDR, "ESPfix Area", 16 }, #endif #ifdef CONFIG_EFI [EFI_END_NR] = { EFI_VA_END, "EFI Runtime Services" }, #endif [HIGH_KERNEL_NR] = { __START_KERNEL_map, "High Kernel Mapping" }, [MODULES_VADDR_NR] = { MODULES_VADDR, "Modules" }, [MODULES_END_NR] = { MODULES_END, "End Modules" }, [FIXADDR_START_NR] = { FIXADDR_START, "Fixmap Area" }, [END_OF_SPACE_NR] = { -1, NULL } }; #else /* CONFIG_X86_64 */ enum address_markers_idx { USER_SPACE_NR = 0, KERNEL_SPACE_NR, VMALLOC_START_NR, VMALLOC_END_NR, #ifdef CONFIG_HIGHMEM PKMAP_BASE_NR, #endif CPU_ENTRY_AREA_NR, FIXADDR_START_NR, END_OF_SPACE_NR, }; static struct addr_marker address_markers[] = { [USER_SPACE_NR] = { 0, "User Space" }, [KERNEL_SPACE_NR] = { PAGE_OFFSET, "Kernel Mapping" }, [VMALLOC_START_NR] = { 0UL, "vmalloc() Area" }, [VMALLOC_END_NR] = { 0UL, "vmalloc() End" }, #ifdef CONFIG_HIGHMEM [PKMAP_BASE_NR] = { 0UL, "Persistent kmap() Area" }, #endif [CPU_ENTRY_AREA_NR] = { 0UL, "CPU entry area" }, [FIXADDR_START_NR] = { 0UL, "Fixmap area" }, [END_OF_SPACE_NR] = { -1, NULL } }; #endif /* !CONFIG_X86_64 */ /* 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 P4D_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT) #define PGD_LEVEL_MULT (PTRS_PER_P4D * P4D_LEVEL_MULT) #define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \ ({ \ if (to_dmesg) \ printk(KERN_INFO fmt, ##args); \ else \ if (m) \ seq_printf(m, fmt, ##args); \ }) #define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \ ({ \ if (to_dmesg) \ printk(KERN_CONT fmt, ##args); \ else \ if (m) \ seq_printf(m, fmt, ##args); \ }) /* * 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, bool dmsg) { pgprotval_t pr = pgprot_val(prot); static const char * const level_name[] = { "cr3", "pgd", "p4d", "pud", "pmd", "pte" }; if (!(pr & _PAGE_PRESENT)) { /* Not present */ pt_dump_cont_printf(m, dmsg, " "); } else { if (pr & _PAGE_USER) pt_dump_cont_printf(m, dmsg, "USR "); else pt_dump_cont_printf(m, dmsg, " "); if (pr & _PAGE_RW) pt_dump_cont_printf(m, dmsg, "RW "); else pt_dump_cont_printf(m, dmsg, "ro "); if (pr & _PAGE_PWT) pt_dump_cont_printf(m, dmsg, "PWT "); else pt_dump_cont_printf(m, dmsg, " "); if (pr & _PAGE_PCD) pt_dump_cont_printf(m, dmsg, "PCD "); else pt_dump_cont_printf(m, dmsg, " "); /* Bit 7 has a different meaning on level 3 vs 4 */ if (level <= 4 && pr & _PAGE_PSE) pt_dump_cont_printf(m, dmsg, "PSE "); else pt_dump_cont_printf(m, dmsg, " "); if ((level == 5 && pr & _PAGE_PAT) || ((level == 4 || level == 3) && pr & _PAGE_PAT_LARGE)) pt_dump_cont_printf(m, dmsg, "PAT "); else pt_dump_cont_printf(m, dmsg, " "); if (pr & _PAGE_GLOBAL) pt_dump_cont_printf(m, dmsg, "GLB "); else pt_dump_cont_printf(m, dmsg, " "); if (pr & _PAGE_NX) pt_dump_cont_printf(m, dmsg, "NX "); else pt_dump_cont_printf(m, dmsg, "x "); } pt_dump_cont_printf(m, dmsg, "%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) { int shift; if (!IS_ENABLED(CONFIG_X86_64)) return u; shift = 64 - (__VIRTUAL_MASK_SHIFT + 1); return (signed long)(u << shift) >> shift; } /* * 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, pgprotval_t new_eff, int level) { pgprotval_t prot, cur, eff; static const char units[] = "BKMGTPE"; /* * 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); cur = pgprot_val(st->current_prot); eff = st->effective_prot; if (!st->level) { /* First entry */ st->current_prot = new_prot; st->effective_prot = new_eff; st->level = level; st->marker = address_markers; st->lines = 0; pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n", st->marker->name); } else if (prot != cur || new_eff != eff || level != st->level || st->current_address >= st->marker[1].start_address) { const char *unit = units; unsigned long delta; int width = sizeof(unsigned long) * 2; if (st->check_wx && (eff & _PAGE_RW) && !(eff & _PAGE_NX)) { WARN_ONCE(1, "x86/mm: Found insecure W+X mapping at address %p/%pS\n", (void *)st->start_address, (void *)st->start_address); st->wx_pages += (st->current_address - st->start_address) / PAGE_SIZE; } /* * Now print the actual finished series */ if (!st->marker->max_lines || st->lines < st->marker->max_lines) { pt_dump_seq_printf(m, st->to_dmesg, "0x%0*lx-0x%0*lx ", width, st->start_address, width, st->current_address); delta = st->current_address - st->start_address; while (!(delta & 1023) && unit[1]) { delta >>= 10; unit++; } pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ", delta, *unit); printk_prot(m, st->current_prot, st->level, st->to_dmesg); } st->lines++; /* * 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) { if (st->marker->max_lines && st->lines > st->marker->max_lines) { unsigned long nskip = st->lines - st->marker->max_lines; pt_dump_seq_printf(m, st->to_dmesg, "... %lu entr%s skipped ... \n", nskip, nskip == 1 ? "y" : "ies"); } st->marker++; st->lines = 0; pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n", st->marker->name); } st->start_address = st->current_address; st->current_prot = new_prot; st->effective_prot = new_eff; st->level = level; } } static inline pgprotval_t effective_prot(pgprotval_t prot1, pgprotval_t prot2) { return (prot1 & prot2 & (_PAGE_USER | _PAGE_RW)) | ((prot1 | prot2) & _PAGE_NX); } static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr, pgprotval_t eff_in, unsigned long P) { int i; pte_t *pte; pgprotval_t prot, eff; for (i = 0; i < PTRS_PER_PTE; i++) { st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT); pte = pte_offset_map(&addr, st->current_address); prot = pte_flags(*pte); eff = effective_prot(eff_in, prot); note_page(m, st, __pgprot(prot), eff, 5); pte_unmap(pte); } } #ifdef CONFIG_KASAN /* * This is an optimization for KASAN=y case. Since all kasan page tables * eventually point to the kasan_zero_page we could call note_page() * right away without walking through lower level page tables. This saves * us dozens of seconds (minutes for 5-level config) while checking for * W+X mapping or reading kernel_page_tables debugfs file. */ static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st, void *pt) { if (__pa(pt) == __pa(kasan_zero_pmd) || (pgtable_l5_enabled() && __pa(pt) == __pa(kasan_zero_p4d)) || __pa(pt) == __pa(kasan_zero_pud)) { pgprotval_t prot = pte_flags(kasan_zero_pte[0]); note_page(m, st, __pgprot(prot), 0, 5); return true; } return false; } #else static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st, void *pt) { return false; } #endif #if PTRS_PER_PMD > 1 static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr, pgprotval_t eff_in, unsigned long P) { int i; pmd_t *start, *pmd_start; pgprotval_t prot, eff; pmd_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)) { prot = pmd_flags(*start); eff = effective_prot(eff_in, prot); if (pmd_large(*start) || !pmd_present(*start)) { note_page(m, st, __pgprot(prot), eff, 4); } else if (!kasan_page_table(m, st, pmd_start)) { walk_pte_level(m, st, *start, eff, P + i * PMD_LEVEL_MULT); } } else note_page(m, st, __pgprot(0), 0, 4); start++; } } #else #define walk_pmd_level(m,s,a,e,p) walk_pte_level(m,s,__pmd(pud_val(a)),e,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, p4d_t addr, pgprotval_t eff_in, unsigned long P) { int i; pud_t *start, *pud_start; pgprotval_t prot, eff; pud_t *prev_pud = NULL; pud_start = start = (pud_t *)p4d_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)) { prot = pud_flags(*start); eff = effective_prot(eff_in, prot); if (pud_large(*start) || !pud_present(*start)) { note_page(m, st, __pgprot(prot), eff, 3); } else if (!kasan_page_table(m, st, pud_start)) { walk_pmd_level(m, st, *start, eff, P + i * PUD_LEVEL_MULT); } } else note_page(m, st, __pgprot(0), 0, 3); prev_pud = start; start++; } } #else #define walk_pud_level(m,s,a,e,p) walk_pmd_level(m,s,__pud(p4d_val(a)),e,p) #define p4d_large(a) pud_large(__pud(p4d_val(a))) #define p4d_none(a) pud_none(__pud(p4d_val(a))) #endif static void walk_p4d_level(struct seq_file *m, struct pg_state *st, pgd_t addr, pgprotval_t eff_in, unsigned long P) { int i; p4d_t *start, *p4d_start; pgprotval_t prot, eff; if (PTRS_PER_P4D == 1) return walk_pud_level(m, st, __p4d(pgd_val(addr)), eff_in, P); p4d_start = start = (p4d_t *)pgd_page_vaddr(addr); for (i = 0; i < PTRS_PER_P4D; i++) { st->current_address = normalize_addr(P + i * P4D_LEVEL_MULT); if (!p4d_none(*start)) { prot = p4d_flags(*start); eff = effective_prot(eff_in, prot); if (p4d_large(*start) || !p4d_present(*start)) { note_page(m, st, __pgprot(prot), eff, 2); } else if (!kasan_page_table(m, st, p4d_start)) { walk_pud_level(m, st, *start, eff, P + i * P4D_LEVEL_MULT); } } else note_page(m, st, __pgprot(0), 0, 2); start++; } } #define pgd_large(a) (pgtable_l5_enabled() ? pgd_large(a) : p4d_large(__p4d(pgd_val(a)))) #define pgd_none(a) (pgtable_l5_enabled() ? pgd_none(a) : p4d_none(__p4d(pgd_val(a)))) static inline bool is_hypervisor_range(int idx) { #ifdef CONFIG_X86_64 /* * ffff800000000000 - ffff87ffffffffff is reserved for * the hypervisor. */ return (idx >= pgd_index(__PAGE_OFFSET) - 16) && (idx < pgd_index(__PAGE_OFFSET)); #else return false; #endif } static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd, bool checkwx, bool dmesg) { #ifdef CONFIG_X86_64 pgd_t *start = (pgd_t *) &init_top_pgt; #else pgd_t *start = swapper_pg_dir; #endif pgprotval_t prot, eff; int i; struct pg_state st = {}; if (pgd) { start = pgd; st.to_dmesg = dmesg; } st.check_wx = checkwx; if (checkwx) st.wx_pages = 0; for (i = 0; i < PTRS_PER_PGD; i++) { st.current_address = normalize_addr(i * PGD_LEVEL_MULT); if (!pgd_none(*start) && !is_hypervisor_range(i)) { prot = pgd_flags(*start); #ifdef CONFIG_X86_PAE eff = _PAGE_USER | _PAGE_RW; #else eff = prot; #endif if (pgd_large(*start) || !pgd_present(*start)) { note_page(m, &st, __pgprot(prot), eff, 1); } else { walk_p4d_level(m, &st, *start, eff, i * PGD_LEVEL_MULT); } } else note_page(m, &st, __pgprot(0), 0, 1); cond_resched(); start++; } /* Flush out the last page */ st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT); note_page(m, &st, __pgprot(0), 0, 0); if (!checkwx) return; if (st.wx_pages) pr_info("x86/mm: Checked W+X mappings: FAILED, %lu W+X pages found.\n", st.wx_pages); else pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n"); } void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd) { ptdump_walk_pgd_level_core(m, pgd, false, true); } void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user) { #ifdef CONFIG_PAGE_TABLE_ISOLATION if (user && static_cpu_has(X86_FEATURE_PTI)) pgd = kernel_to_user_pgdp(pgd); #endif ptdump_walk_pgd_level_core(m, pgd, false, false); } EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs); static void ptdump_walk_user_pgd_level_checkwx(void) { #ifdef CONFIG_PAGE_TABLE_ISOLATION pgd_t *pgd = (pgd_t *) &init_top_pgt; if (!static_cpu_has(X86_FEATURE_PTI)) return; pr_info("x86/mm: Checking user space page tables\n"); pgd = kernel_to_user_pgdp(pgd); ptdump_walk_pgd_level_core(NULL, pgd, true, false); #endif } void ptdump_walk_pgd_level_checkwx(void) { ptdump_walk_pgd_level_core(NULL, NULL, true, false); ptdump_walk_user_pgd_level_checkwx(); } static int __init pt_dump_init(void) { /* * Various markers are not compile-time constants, so assign them * here. */ #ifdef CONFIG_X86_64 address_markers[LOW_KERNEL_NR].start_address = PAGE_OFFSET; address_markers[VMALLOC_START_NR].start_address = VMALLOC_START; address_markers[VMEMMAP_START_NR].start_address = VMEMMAP_START; #ifdef CONFIG_MODIFY_LDT_SYSCALL address_markers[LDT_NR].start_address = LDT_BASE_ADDR; #endif #ifdef CONFIG_KASAN address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START; address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END; #endif #endif #ifdef CONFIG_X86_32 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START; address_markers[VMALLOC_END_NR].start_address = VMALLOC_END; # ifdef CONFIG_HIGHMEM address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE; # endif address_markers[FIXADDR_START_NR].start_address = FIXADDR_START; address_markers[CPU_ENTRY_AREA_NR].start_address = CPU_ENTRY_AREA_BASE; #endif return 0; } __initcall(pt_dump_init);