// 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);	/* To stabilise kernel page tables we must hold the init_mm lock too. */	if (mm != &init_mm)		mmap_write_lock_nested(&init_mm, SINGLE_DEPTH_NESTING); 	while (range->start != range->end) {		walk_page_range_debug(mm, range->start, range->end,				      &ptdump_ops, pgd, st);		range++;	} 	if (mm != &init_mm)		mmap_write_unlock(&init_mm);	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);