diff options
Diffstat (limited to 'mm/ptdump.c')
| -rw-r--r-- | mm/ptdump.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/mm/ptdump.c b/mm/ptdump.c new file mode 100644 index 000000000000..973020000096 --- /dev/null +++ b/mm/ptdump.c @@ -0,0 +1,212 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/pagewalk.h> +#include <linux/debugfs.h> +#include <linux/ptdump.h> +#include <linux/kasan.h> +#include "internal.h" + +#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) +/* + * This is an optimization for KASAN=y case. Since all kasan page tables + * eventually point to the kasan_early_shadow_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 int note_kasan_page_table(struct mm_walk *walk, + unsigned long addr) +{ + struct ptdump_state *st = walk->private; + + st->note_page_pte(st, addr, kasan_early_shadow_pte[0]); + + walk->action = ACTION_CONTINUE; + + return 0; +} +#endif + +static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr, + unsigned long next, struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + pgd_t val = pgdp_get(pgd); + +#if CONFIG_PGTABLE_LEVELS > 4 && \ + (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) + if (pgd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_p4d))) + return note_kasan_page_table(walk, addr); +#endif + + if (st->effective_prot_pgd) + st->effective_prot_pgd(st, val); + + if (pgd_leaf(val)) { + st->note_page_pgd(st, addr, val); + walk->action = ACTION_CONTINUE; + } + + return 0; +} + +static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr, + unsigned long next, struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + p4d_t val = p4dp_get(p4d); + +#if CONFIG_PGTABLE_LEVELS > 3 && \ + (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) + if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud))) + return note_kasan_page_table(walk, addr); +#endif + + if (st->effective_prot_p4d) + st->effective_prot_p4d(st, val); + + if (p4d_leaf(val)) { + st->note_page_p4d(st, addr, val); + walk->action = ACTION_CONTINUE; + } + + return 0; +} + +static int ptdump_pud_entry(pud_t *pud, unsigned long addr, + unsigned long next, struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + pud_t val = pudp_get(pud); + +#if CONFIG_PGTABLE_LEVELS > 2 && \ + (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) + if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd))) + return note_kasan_page_table(walk, addr); +#endif + + if (st->effective_prot_pud) + st->effective_prot_pud(st, val); + + if (pud_leaf(val)) { + st->note_page_pud(st, addr, val); + walk->action = ACTION_CONTINUE; + } + + return 0; +} + +static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr, + unsigned long next, struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + pmd_t val = pmdp_get(pmd); + +#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) + if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte))) + return note_kasan_page_table(walk, addr); +#endif + + if (st->effective_prot_pmd) + st->effective_prot_pmd(st, val); + if (pmd_leaf(val)) { + st->note_page_pmd(st, addr, val); + walk->action = ACTION_CONTINUE; + } + + return 0; +} + +static int ptdump_pte_entry(pte_t *pte, unsigned long addr, + unsigned long next, struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + pte_t val = ptep_get(pte); + + if (st->effective_prot_pte) + st->effective_prot_pte(st, val); + + st->note_page_pte(st, addr, val); + + return 0; +} + +static int ptdump_hole(unsigned long addr, unsigned long next, + int depth, struct mm_walk *walk) +{ + struct ptdump_state *st = walk->private; + pte_t pte_zero = {0}; + pmd_t pmd_zero = {0}; + pud_t pud_zero = {0}; + p4d_t p4d_zero = {0}; + pgd_t pgd_zero = {0}; + + switch (depth) { + case 4: + st->note_page_pte(st, addr, pte_zero); + break; + case 3: + st->note_page_pmd(st, addr, pmd_zero); + break; + case 2: + st->note_page_pud(st, addr, pud_zero); + break; + case 1: + st->note_page_p4d(st, addr, p4d_zero); + break; + case 0: + st->note_page_pgd(st, addr, pgd_zero); + break; + default: + break; + } + return 0; +} + +static const struct mm_walk_ops ptdump_ops = { + .pgd_entry = ptdump_pgd_entry, + .p4d_entry = ptdump_p4d_entry, + .pud_entry = ptdump_pud_entry, + .pmd_entry = ptdump_pmd_entry, + .pte_entry = ptdump_pte_entry, + .pte_hole = ptdump_hole, +}; + +void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd) +{ + const struct ptdump_range *range = st->range; + + get_online_mems(); + mmap_write_lock(mm); + while (range->start != range->end) { + walk_page_range_debug(mm, range->start, range->end, + &ptdump_ops, pgd, st); + range++; + } + mmap_write_unlock(mm); + put_online_mems(); + + /* Flush out the last page */ + st->note_page_flush(st); +} + +static int check_wx_show(struct seq_file *m, void *v) +{ + if (ptdump_check_wx()) + seq_puts(m, "SUCCESS\n"); + else + seq_puts(m, "FAILED\n"); + + return 0; +} + +DEFINE_SHOW_ATTRIBUTE(check_wx); + +static int ptdump_debugfs_init(void) +{ + debugfs_create_file("check_wx_pages", 0400, NULL, NULL, &check_wx_fops); + + return 0; +} + +device_initcall(ptdump_debugfs_init); |