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Diffstat (limited to '')
| -rw-r--r-- | arch/powerpc/mm/ptdump/ptdump.c | 472 |
1 files changed, 472 insertions, 0 deletions
diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c new file mode 100644 index 000000000..aca354fb6 --- /dev/null +++ b/arch/powerpc/mm/ptdump/ptdump.c @@ -0,0 +1,472 @@ +// 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 <linux/const.h> +#include <asm/page.h> +#include <asm/hugetlb.h> + +#include <mm/mmu_decl.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" }, +#ifdef MODULES_VADDR + { 0, "modules start" }, + { 0, "modules end" }, +#endif + { 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); \ +}) + +void pt_dump_size(struct seq_file *m, unsigned long size) +{ + static const char units[] = "KMGTPE"; + const char *unit = units; + + /* Work out what appropriate unit to use */ + while (!(size & 1023) && unit[1]) { + size >>= 10; + unit++; + } + pt_dump_seq_printf(m, "%9lu%c ", size, *unit); +} + +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) +{ + 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; + } + pt_dump_size(st->seq, delta); +} + +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_update_state(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; + + st->level = level; + st->current_flags = flag; + st->start_address = addr; + st->start_pa = pa; + st->page_size = page_size; + + while (addr >= st->marker[1].start_address) { + st->marker++; + pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); + } +} + +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) { + pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); + note_page_update_state(st, addr, level, val, page_size); + /* + * 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 + */ + note_page_update_state(st, addr, level, val, page_size); + } + 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_hugepd(struct pg_state *st, hugepd_t *phpd, unsigned long start, + int pdshift, int level) +{ +#ifdef CONFIG_ARCH_HAS_HUGEPD + unsigned int i; + int shift = hugepd_shift(*phpd); + int ptrs_per_hpd = pdshift - shift > 0 ? 1 << (pdshift - shift) : 1; + + if (start & ((1 << shift) - 1)) + return; + + for (i = 0; i < ptrs_per_hpd; i++) { + unsigned long addr = start + (i << shift); + pte_t *pte = hugepte_offset(*phpd, addr, pdshift); + + note_page(st, addr, level + 1, pte_val(*pte), 1 << shift); + } +#endif +} + +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, p4d_t *p4d, unsigned long start) +{ + pud_t *pud = pud_offset(p4d, 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) { + p4d_t *p4d = p4d_offset(pgd, 0); + + if (p4d_none(*p4d) || p4d_is_leaf(*p4d)) + note_page(st, addr, 1, p4d_val(*p4d), PGDIR_SIZE); + else if (is_hugepd(__hugepd(p4d_val(*p4d)))) + walk_hugepd(st, (hugepd_t *)p4d, addr, PGDIR_SHIFT, 1); + else + /* p4d exists */ + walk_pud(st, p4d, addr); + } +} + +static void populate_markers(void) +{ + int i = 0; + +#ifdef CONFIG_PPC64 + address_markers[i++].start_address = PAGE_OFFSET; +#else + address_markers[i++].start_address = TASK_SIZE; +#endif +#ifdef MODULES_VADDR + address_markers[i++].start_address = MODULES_VADDR; + address_markers[i++].start_address = MODULES_END; +#endif + 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 = IS_ENABLED(CONFIG_PPC64) ? PAGE_OFFSET : TASK_SIZE, + }; + +#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 = IS_ENABLED(CONFIG_PPC64) ? PAGE_OFFSET : TASK_SIZE, + }; + +#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) +{ + populate_markers(); + build_pgtable_complete_mask(); + debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, + &ptdump_fops); + return 0; +} +device_initcall(ptdump_init); |