// 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. * * (C) Copyright 2008 Intel Corporation * * Author: Arjan van de Ven */ #include #include #include #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 { struct ptdump_state ptdump; int level; pgprotval_t current_prot; pgprotval_t effective_prot; pgprotval_t prot_levels[5]; unsigned long start_address; const struct addr_marker *marker; unsigned long lines; bool to_dmesg; bool check_wx; unsigned long wx_pages; struct seq_file *seq; }; 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, #ifdef CONFIG_MODIFY_LDT_SYSCALL LDT_NR, #endif LOW_KERNEL_NR, VMALLOC_START_NR, VMEMMAP_START_NR, #ifdef CONFIG_KASAN KASAN_SHADOW_START_NR, KASAN_SHADOW_END_NR, #endif CPU_ENTRY_AREA_NR, #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 } }; #define INIT_PGD ((pgd_t *) &init_top_pgt) #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 #ifdef CONFIG_MODIFY_LDT_SYSCALL LDT_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 #ifdef CONFIG_MODIFY_LDT_SYSCALL [LDT_NR] = { 0UL, "LDT remap" }, #endif [CPU_ENTRY_AREA_NR] = { 0UL, "CPU entry area" }, [FIXADDR_START_NR] = { 0UL, "Fixmap area" }, [END_OF_SPACE_NR] = { -1, NULL } }; #define INIT_PGD (swapper_pg_dir) #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, pgprotval_t pr, int level, bool dmsg) { static const char * const level_name[] = { "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 <= 3 && pr & _PAGE_PSE) pt_dump_cont_printf(m, dmsg, "PSE "); else pt_dump_cont_printf(m, dmsg, " "); if ((level == 4 && pr & _PAGE_PAT) || ((level == 3 || level == 2) && 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]); } static void note_wx(struct pg_state *st, unsigned long addr) { unsigned long npages; npages = (addr - st->start_address) / PAGE_SIZE; #ifdef CONFIG_PCI_BIOS /* * If PCI BIOS is enabled, the PCI BIOS area is forced to WX. * Inform about it, but avoid the warning. */ if (pcibios_enabled && st->start_address >= PAGE_OFFSET + BIOS_BEGIN && addr <= PAGE_OFFSET + BIOS_END) { pr_warn_once("x86/mm: PCI BIOS W+X mapping %lu pages\n", npages); return; } #endif /* Account the WX pages */ st->wx_pages += npages; WARN_ONCE(__supported_pte_mask & _PAGE_NX, "x86/mm: Found insecure W+X mapping at address %pS\n", (void *)st->start_address); } static inline pgprotval_t effective_prot(pgprotval_t prot1, pgprotval_t prot2) { return (prot1 & prot2 & (_PAGE_USER | _PAGE_RW)) | ((prot1 | prot2) & _PAGE_NX); } /* * 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 ptdump_state *pt_st, unsigned long addr, int level, unsigned long val) { struct pg_state *st = container_of(pt_st, struct pg_state, ptdump); pgprotval_t new_prot, new_eff; pgprotval_t cur, eff; static const char units[] = "BKMGTPE"; struct seq_file *m = st->seq; new_prot = val & PTE_FLAGS_MASK; if (level > 0) { new_eff = effective_prot(st->prot_levels[level - 1], new_prot); } else { new_eff = new_prot; } if (level >= 0) st->prot_levels[level] = new_eff; /* * 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. */ cur = st->current_prot; eff = st->effective_prot; if (st->level == -1) { /* 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 (new_prot != cur || new_eff != eff || level != st->level || addr >= 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)) note_wx(st, addr); /* * 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, addr); delta = addr - 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 (addr >= 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 = addr; st->current_prot = new_prot; st->effective_prot = new_eff; st->level = level; } } static void ptdump_walk_pgd_level_core(struct seq_file *m, struct mm_struct *mm, pgd_t *pgd, bool checkwx, bool dmesg) { const struct ptdump_range ptdump_ranges[] = { #ifdef CONFIG_X86_64 {0, PTRS_PER_PGD * PGD_LEVEL_MULT / 2}, {GUARD_HOLE_END_ADDR, ~0UL}, #else {0, ~0UL}, #endif {0, 0} }; struct pg_state st = { .ptdump = { .note_page = note_page, .range = ptdump_ranges }, .level = -1, .to_dmesg = dmesg, .check_wx = checkwx, .seq = m }; ptdump_walk_pgd(&st.ptdump, mm, pgd); 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, struct mm_struct *mm) { ptdump_walk_pgd_level_core(m, mm, mm->pgd, false, true); } void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm, bool user) { pgd_t *pgd = mm->pgd; #ifdef CONFIG_PAGE_TABLE_ISOLATION if (user && boot_cpu_has(X86_FEATURE_PTI)) pgd = kernel_to_user_pgdp(pgd); #endif ptdump_walk_pgd_level_core(m, mm, pgd, false, false); } EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs); void ptdump_walk_user_pgd_level_checkwx(void) { #ifdef CONFIG_PAGE_TABLE_ISOLATION pgd_t *pgd = INIT_PGD; if (!(__supported_pte_mask & _PAGE_NX) || !boot_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, &init_mm, pgd, true, false); #endif } void ptdump_walk_pgd_level_checkwx(void) { ptdump_walk_pgd_level_core(NULL, &init_mm, INIT_PGD, true, false); } 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; # ifdef CONFIG_MODIFY_LDT_SYSCALL address_markers[LDT_NR].start_address = LDT_BASE_ADDR; # endif #endif return 0; } __initcall(pt_dump_init);