| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * Copyright 2016, Rashmica Gupta, IBM Corp. |
| * |
| * This traverses the kernel pagetables and dumps the |
| * information about the used sections of memory to |
| * /sys/kernel/debug/kernel_pagetables. |
| * |
| * Derived from the arm64 implementation: |
| * Copyright (c) 2014, The Linux Foundation, Laura Abbott. |
| * (C) Copyright 2008 Intel Corporation, Arjan van de Ven. |
| */ |
| #include <linux/debugfs.h> |
| #include <linux/fs.h> |
| #include <linux/hugetlb.h> |
| #include <linux/io.h> |
| #include <linux/mm.h> |
| #include <linux/highmem.h> |
| #include <linux/sched.h> |
| #include <linux/seq_file.h> |
| #include <asm/fixmap.h> |
| #include <asm/pgtable.h> |
| #include <linux/const.h> |
| #include <asm/page.h> |
| #include <asm/pgalloc.h> |
| |
| #include "ptdump.h" |
| |
| /* |
| * To visualise what is happening, |
| * |
| * - PTRS_PER_P** = how many entries there are in the corresponding P** |
| * - P**_SHIFT = how many bits of the address we use to index into the |
| * corresponding P** |
| * - P**_SIZE is how much memory we can access through the table - not the |
| * size of the table itself. |
| * P**={PGD, PUD, PMD, PTE} |
| * |
| * |
| * Each entry of the PGD points to a PUD. Each entry of a PUD points to a |
| * PMD. Each entry of a PMD points to a PTE. And every PTE entry points to |
| * a page. |
| * |
| * In the case where there are only 3 levels, the PUD is folded into the |
| * PGD: every PUD has only one entry which points to the PMD. |
| * |
| * The page dumper groups page table entries of the same type into a single |
| * description. It uses pg_state to track the range information while |
| * iterating over the PTE entries. When the continuity is broken it then |
| * dumps out a description of the range - ie PTEs that are virtually contiguous |
| * with the same PTE flags are chunked together. This is to make it clear how |
| * different areas of the kernel virtual memory are used. |
| * |
| */ |
| struct pg_state { |
| struct seq_file *seq; |
| const struct addr_marker *marker; |
| unsigned long start_address; |
| unsigned long start_pa; |
| unsigned long last_pa; |
| unsigned long page_size; |
| unsigned int level; |
| u64 current_flags; |
| bool check_wx; |
| unsigned long wx_pages; |
| }; |
| |
| struct addr_marker { |
| unsigned long start_address; |
| const char *name; |
| }; |
| |
| static struct addr_marker address_markers[] = { |
| { 0, "Start of kernel VM" }, |
| { 0, "vmalloc() Area" }, |
| { 0, "vmalloc() End" }, |
| #ifdef CONFIG_PPC64 |
| { 0, "isa I/O start" }, |
| { 0, "isa I/O end" }, |
| { 0, "phb I/O start" }, |
| { 0, "phb I/O end" }, |
| { 0, "I/O remap start" }, |
| { 0, "I/O remap end" }, |
| { 0, "vmemmap start" }, |
| #else |
| { 0, "Early I/O remap start" }, |
| { 0, "Early I/O remap end" }, |
| #ifdef CONFIG_HIGHMEM |
| { 0, "Highmem PTEs start" }, |
| { 0, "Highmem PTEs end" }, |
| #endif |
| { 0, "Fixmap start" }, |
| { 0, "Fixmap end" }, |
| #endif |
| #ifdef CONFIG_KASAN |
| { 0, "kasan shadow mem start" }, |
| { 0, "kasan shadow mem end" }, |
| #endif |
| { -1, NULL }, |
| }; |
| |
| #define pt_dump_seq_printf(m, fmt, args...) \ |
| ({ \ |
| if (m) \ |
| seq_printf(m, fmt, ##args); \ |
| }) |
| |
| #define pt_dump_seq_putc(m, c) \ |
| ({ \ |
| if (m) \ |
| seq_putc(m, c); \ |
| }) |
| |
| static void dump_flag_info(struct pg_state *st, const struct flag_info |
| *flag, u64 pte, int num) |
| { |
| unsigned int i; |
| |
| for (i = 0; i < num; i++, flag++) { |
| const char *s = NULL; |
| u64 val; |
| |
| /* flag not defined so don't check it */ |
| if (flag->mask == 0) |
| continue; |
| /* Some 'flags' are actually values */ |
| if (flag->is_val) { |
| val = pte & flag->val; |
| if (flag->shift) |
| val = val >> flag->shift; |
| pt_dump_seq_printf(st->seq, " %s:%llx", flag->set, val); |
| } else { |
| if ((pte & flag->mask) == flag->val) |
| s = flag->set; |
| else |
| s = flag->clear; |
| if (s) |
| pt_dump_seq_printf(st->seq, " %s", s); |
| } |
| st->current_flags &= ~flag->mask; |
| } |
| if (st->current_flags != 0) |
| pt_dump_seq_printf(st->seq, " unknown flags:%llx", st->current_flags); |
| } |
| |
| static void dump_addr(struct pg_state *st, unsigned long addr) |
| { |
| static const char units[] = "KMGTPE"; |
| const char *unit = units; |
| unsigned long delta; |
| |
| #ifdef CONFIG_PPC64 |
| #define REG "0x%016lx" |
| #else |
| #define REG "0x%08lx" |
| #endif |
| |
| pt_dump_seq_printf(st->seq, REG "-" REG " ", st->start_address, addr - 1); |
| if (st->start_pa == st->last_pa && st->start_address + st->page_size != addr) { |
| pt_dump_seq_printf(st->seq, "[" REG "]", st->start_pa); |
| delta = st->page_size >> 10; |
| } else { |
| pt_dump_seq_printf(st->seq, " " REG " ", st->start_pa); |
| delta = (addr - st->start_address) >> 10; |
| } |
| /* Work out what appropriate unit to use */ |
| while (!(delta & 1023) && unit[1]) { |
| delta >>= 10; |
| unit++; |
| } |
| pt_dump_seq_printf(st->seq, "%9lu%c", delta, *unit); |
| |
| } |
| |
| static void note_prot_wx(struct pg_state *st, unsigned long addr) |
| { |
| pte_t pte = __pte(st->current_flags); |
| |
| if (!IS_ENABLED(CONFIG_PPC_DEBUG_WX) || !st->check_wx) |
| return; |
| |
| if (!pte_write(pte) || !pte_exec(pte)) |
| return; |
| |
| WARN_ONCE(1, "powerpc/mm: Found insecure W+X mapping at address %p/%pS\n", |
| (void *)st->start_address, (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, unsigned long page_size) |
| { |
| u64 flag = val & pg_level[level].mask; |
| u64 pa = val & PTE_RPN_MASK; |
| |
| /* At first no level is set */ |
| if (!st->level) { |
| st->level = level; |
| st->current_flags = flag; |
| st->start_address = addr; |
| st->start_pa = pa; |
| st->last_pa = pa; |
| st->page_size = page_size; |
| pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); |
| /* |
| * Dump the section of virtual memory when: |
| * - the PTE flags from one entry to the next differs. |
| * - we change levels in the tree. |
| * - the address is in a different section of memory and is thus |
| * used for a different purpose, regardless of the flags. |
| * - the pa of this page is not adjacent to the last inspected page |
| */ |
| } else if (flag != st->current_flags || level != st->level || |
| addr >= st->marker[1].start_address || |
| (pa != st->last_pa + st->page_size && |
| (pa != st->start_pa || st->start_pa != st->last_pa))) { |
| |
| /* Check the PTE flags */ |
| if (st->current_flags) { |
| note_prot_wx(st, addr); |
| dump_addr(st, addr); |
| |
| /* Dump all the flags */ |
| if (pg_level[st->level].flag) |
| dump_flag_info(st, pg_level[st->level].flag, |
| st->current_flags, |
| pg_level[st->level].num); |
| |
| pt_dump_seq_putc(st->seq, '\n'); |
| } |
| |
| /* |
| * Address indicates we have passed the end of the |
| * current section of virtual memory |
| */ |
| while (addr >= st->marker[1].start_address) { |
| st->marker++; |
| pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); |
| } |
| st->start_address = addr; |
| st->start_pa = pa; |
| st->last_pa = pa; |
| st->page_size = page_size; |
| st->current_flags = flag; |
| st->level = level; |
| } else { |
| st->last_pa = pa; |
| } |
| } |
| |
| static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start) |
| { |
| pte_t *pte = pte_offset_kernel(pmd, 0); |
| unsigned long addr; |
| unsigned int i; |
| |
| for (i = 0; i < PTRS_PER_PTE; i++, pte++) { |
| addr = start + i * PAGE_SIZE; |
| note_page(st, addr, 4, pte_val(*pte), PAGE_SIZE); |
| |
| } |
| } |
| |
| 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 int i; |
| |
| for (i = 0; i < PTRS_PER_PMD; i++, pmd++) { |
| addr = start + i * PMD_SIZE; |
| if (!pmd_none(*pmd) && !pmd_is_leaf(*pmd)) |
| /* pmd exists */ |
| walk_pte(st, pmd, addr); |
| else |
| note_page(st, addr, 3, pmd_val(*pmd), PMD_SIZE); |
| } |
| } |
| |
| static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start) |
| { |
| pud_t *pud = pud_offset(pgd, 0); |
| unsigned long addr; |
| unsigned int i; |
| |
| for (i = 0; i < PTRS_PER_PUD; i++, pud++) { |
| addr = start + i * PUD_SIZE; |
| if (!pud_none(*pud) && !pud_is_leaf(*pud)) |
| /* pud exists */ |
| walk_pmd(st, pud, addr); |
| else |
| note_page(st, addr, 2, pud_val(*pud), PUD_SIZE); |
| } |
| } |
| |
| static void walk_pagetables(struct pg_state *st) |
| { |
| unsigned int i; |
| unsigned long addr = st->start_address & PGDIR_MASK; |
| pgd_t *pgd = pgd_offset_k(addr); |
| |
| /* |
| * Traverse the linux pagetable structure and dump pages that are in |
| * the hash pagetable. |
| */ |
| for (i = pgd_index(addr); i < PTRS_PER_PGD; i++, pgd++, addr += PGDIR_SIZE) { |
| if (!pgd_none(*pgd) && !pgd_is_leaf(*pgd)) |
| /* pgd exists */ |
| walk_pud(st, pgd, addr); |
| else |
| note_page(st, addr, 1, pgd_val(*pgd), PGDIR_SIZE); |
| } |
| } |
| |
| static void populate_markers(void) |
| { |
| int i = 0; |
| |
| address_markers[i++].start_address = PAGE_OFFSET; |
| address_markers[i++].start_address = VMALLOC_START; |
| address_markers[i++].start_address = VMALLOC_END; |
| #ifdef CONFIG_PPC64 |
| address_markers[i++].start_address = ISA_IO_BASE; |
| address_markers[i++].start_address = ISA_IO_END; |
| address_markers[i++].start_address = PHB_IO_BASE; |
| address_markers[i++].start_address = PHB_IO_END; |
| address_markers[i++].start_address = IOREMAP_BASE; |
| address_markers[i++].start_address = IOREMAP_END; |
| /* What is the ifdef about? */ |
| #ifdef CONFIG_PPC_BOOK3S_64 |
| address_markers[i++].start_address = H_VMEMMAP_START; |
| #else |
| address_markers[i++].start_address = VMEMMAP_BASE; |
| #endif |
| #else /* !CONFIG_PPC64 */ |
| address_markers[i++].start_address = ioremap_bot; |
| address_markers[i++].start_address = IOREMAP_TOP; |
| #ifdef CONFIG_HIGHMEM |
| address_markers[i++].start_address = PKMAP_BASE; |
| address_markers[i++].start_address = PKMAP_ADDR(LAST_PKMAP); |
| #endif |
| address_markers[i++].start_address = FIXADDR_START; |
| address_markers[i++].start_address = FIXADDR_TOP; |
| #ifdef CONFIG_KASAN |
| address_markers[i++].start_address = KASAN_SHADOW_START; |
| address_markers[i++].start_address = KASAN_SHADOW_END; |
| #endif |
| #endif /* CONFIG_PPC64 */ |
| } |
| |
| static int ptdump_show(struct seq_file *m, void *v) |
| { |
| struct pg_state st = { |
| .seq = m, |
| .marker = address_markers, |
| .start_address = PAGE_OFFSET, |
| }; |
| |
| #ifdef CONFIG_PPC64 |
| if (!radix_enabled()) |
| st.start_address = KERN_VIRT_START; |
| #endif |
| |
| /* Traverse kernel page tables */ |
| walk_pagetables(&st); |
| note_page(&st, 0, 0, 0, 0); |
| return 0; |
| } |
| |
| |
| static int ptdump_open(struct inode *inode, struct file *file) |
| { |
| return single_open(file, ptdump_show, NULL); |
| } |
| |
| static const struct file_operations ptdump_fops = { |
| .open = ptdump_open, |
| .read = seq_read, |
| .llseek = seq_lseek, |
| .release = single_release, |
| }; |
| |
| static void build_pgtable_complete_mask(void) |
| { |
| unsigned int i, j; |
| |
| for (i = 0; i < ARRAY_SIZE(pg_level); i++) |
| if (pg_level[i].flag) |
| for (j = 0; j < pg_level[i].num; j++) |
| pg_level[i].mask |= pg_level[i].flag[j].mask; |
| } |
| |
| #ifdef CONFIG_PPC_DEBUG_WX |
| void ptdump_check_wx(void) |
| { |
| struct pg_state st = { |
| .seq = NULL, |
| .marker = address_markers, |
| .check_wx = true, |
| .start_address = PAGE_OFFSET, |
| }; |
| |
| #ifdef CONFIG_PPC64 |
| if (!radix_enabled()) |
| st.start_address = KERN_VIRT_START; |
| #endif |
| |
| walk_pagetables(&st); |
| |
| 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"); |
| } |
| #endif |
| |
| static int ptdump_init(void) |
| { |
| struct dentry *debugfs_file; |
| |
| populate_markers(); |
| build_pgtable_complete_mask(); |
| debugfs_file = debugfs_create_file("kernel_page_tables", 0400, NULL, |
| NULL, &ptdump_fops); |
| return debugfs_file ? 0 : -ENOMEM; |
| } |
| device_initcall(ptdump_init); |