/* * 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 /* * 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; 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; }; /* indices for address_markers; keep sync'd w/ address_markers below */ enum address_markers_idx { USER_SPACE_NR = 0, #ifdef CONFIG_X86_64 KERNEL_SPACE_NR, LOW_KERNEL_NR, VMALLOC_START_NR, VMEMMAP_START_NR, #ifdef CONFIG_KASAN KASAN_SHADOW_START_NR, KASAN_SHADOW_END_NR, #endif # ifdef CONFIG_X86_ESPFIX64 ESPFIX_START_NR, # endif HIGH_KERNEL_NR, MODULES_VADDR_NR, MODULES_END_NR, #else KERNEL_SPACE_NR, VMALLOC_START_NR, VMALLOC_END_NR, # ifdef CONFIG_HIGHMEM PKMAP_BASE_NR, # endif FIXADDR_START_NR, #endif }; /* Address space markers hints */ static struct addr_marker address_markers[] = { { 0, "User Space" }, #ifdef CONFIG_X86_64 { 0x8000000000000000UL, "Kernel Space" }, { 0/* PAGE_OFFSET */, "Low Kernel Mapping" }, { 0/* VMALLOC_START */, "vmalloc() Area" }, { 0/* VMEMMAP_START */, "Vmemmap" }, #ifdef CONFIG_KASAN { KASAN_SHADOW_START, "KASAN shadow" }, { KASAN_SHADOW_END, "KASAN shadow end" }, #endif # ifdef CONFIG_X86_ESPFIX64 { ESPFIX_BASE_ADDR, "ESPfix Area", 16 }, # endif # ifdef CONFIG_EFI { EFI_VA_END, "EFI Runtime Services" }, # endif { __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*/, "Persistent 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 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 (!pgprot_val(prot)) { /* 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, int level) { pgprotval_t prot, cur; 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); if (!st->level) { /* First entry */ st->current_prot = new_prot; 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 || level != st->level || st->current_address >= st->marker[1].start_address) { const char *unit = units; unsigned long delta; int width = sizeof(unsigned long) * 2; pgprotval_t pr = pgprot_val(st->current_prot); if (st->check_wx && (pr & _PAGE_RW) && !(pr & _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->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; pgprotval_t prot; start = (pte_t *)pmd_page_vaddr(addr); for (i = 0; i < PTRS_PER_PTE; i++) { prot = pte_flags(*start); st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT); note_page(m, st, __pgprot(prot), 5); 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; pgprotval_t prot; 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)) { if (pmd_large(*start) || !pmd_present(*start)) { prot = pmd_flags(*start); note_page(m, st, __pgprot(prot), 4); } else { walk_pte_level(m, st, *start, P + i * PMD_LEVEL_MULT); } } else note_page(m, st, __pgprot(0), 4); 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 /* * This is an optimization for CONFIG_DEBUG_WX=y + CONFIG_KASAN=y * KASAN fills page tables with the same values. Since there is no * point in checking page table more than once we just skip repeated * entries. This saves us dozens of seconds during boot. */ static bool pud_already_checked(pud_t *prev_pud, pud_t *pud, bool checkwx) { return checkwx && prev_pud && (pud_val(*prev_pud) == pud_val(*pud)); } static void walk_pud_level(struct seq_file *m, struct pg_state *st, p4d_t addr, unsigned long P) { int i; pud_t *start; pgprotval_t prot; pud_t *prev_pud = NULL; 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) && !pud_already_checked(prev_pud, start, st->check_wx)) { if (pud_large(*start) || !pud_present(*start)) { prot = pud_flags(*start); note_page(m, st, __pgprot(prot), 3); } else { walk_pmd_level(m, st, *start, P + i * PUD_LEVEL_MULT); } } else note_page(m, st, __pgprot(0), 3); prev_pud = start; start++; } } #else #define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(p4d_val(a)),p) #define p4d_large(a) pud_large(__pud(p4d_val(a))) #define p4d_none(a) pud_none(__pud(p4d_val(a))) #endif #if PTRS_PER_P4D > 1 static void walk_p4d_level(struct seq_file *m, struct pg_state *st, pgd_t addr, unsigned long P) { int i; p4d_t *start; pgprotval_t prot; 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)) { if (p4d_large(*start) || !p4d_present(*start)) { prot = p4d_flags(*start); note_page(m, st, __pgprot(prot), 2); } else { walk_pud_level(m, st, *start, P + i * P4D_LEVEL_MULT); } } else note_page(m, st, __pgprot(0), 2); start++; } } #else #define walk_p4d_level(m,s,a,p) walk_pud_level(m,s,__p4d(pgd_val(a)),p) #define pgd_large(a) p4d_large(__p4d(pgd_val(a))) #define pgd_none(a) p4d_none(__p4d(pgd_val(a))) #endif 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) { #ifdef CONFIG_X86_64 pgd_t *start = (pgd_t *) &init_top_pgt; #else pgd_t *start = swapper_pg_dir; #endif pgprotval_t prot; int i; struct pg_state st = {}; if (pgd) { start = pgd; st.to_dmesg = true; } 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)) { if (pgd_large(*start) || !pgd_present(*start)) { prot = pgd_flags(*start); note_page(m, &st, __pgprot(prot), 1); } else { walk_p4d_level(m, &st, *start, i * PGD_LEVEL_MULT); } } else note_page(m, &st, __pgprot(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); 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); } EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level); void ptdump_walk_pgd_level_checkwx(void) { ptdump_walk_pgd_level_core(NULL, NULL, true); } 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; #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; #endif return 0; } __initcall(pt_dump_init);