From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- arch/arm/mm/dump.c | 479 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 479 insertions(+) create mode 100644 arch/arm/mm/dump.c (limited to 'arch/arm/mm/dump.c') diff --git a/arch/arm/mm/dump.c b/arch/arm/mm/dump.c new file mode 100644 index 000000000..cd032522d --- /dev/null +++ b/arch/arm/mm/dump.c @@ -0,0 +1,479 @@ +// 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. + * + * Derived from x86 implementation: + * (C) Copyright 2008 Intel Corporation + * + * Author: Arjan van de Ven + */ +#include +#include +#include +#include + +#include +#include +#include +#include + +static struct addr_marker address_markers[] = { +#ifdef CONFIG_KASAN + { KASAN_SHADOW_START, "Kasan shadow start"}, + { KASAN_SHADOW_END, "Kasan shadow end"}, +#endif + { MODULES_VADDR, "Modules" }, + { PAGE_OFFSET, "Kernel Mapping" }, + { 0, "vmalloc() Area" }, + { FDT_FIXED_BASE, "FDT Area" }, + { FIXADDR_START, "Fixmap Area" }, + { VECTORS_BASE, "Vectors" }, + { VECTORS_BASE + PAGE_SIZE * 2, "Vectors End" }, + { -1, NULL }, +}; + +#define pt_dump_seq_printf(m, fmt, args...) \ +({ \ + if (m) \ + seq_printf(m, fmt, ##args); \ +}) + +#define pt_dump_seq_puts(m, fmt) \ +({ \ + if (m) \ + seq_printf(m, fmt); \ +}) + +struct pg_state { + struct seq_file *seq; + const struct addr_marker *marker; + unsigned long start_address; + unsigned level; + u64 current_prot; + bool check_wx; + unsigned long wx_pages; + const char *current_domain; +}; + +struct prot_bits { + u64 mask; + u64 val; + const char *set; + const char *clear; + bool ro_bit; + bool nx_bit; +}; + +static const struct prot_bits pte_bits[] = { + { + .mask = L_PTE_USER, + .val = L_PTE_USER, + .set = "USR", + .clear = " ", + }, { + .mask = L_PTE_RDONLY, + .val = L_PTE_RDONLY, + .set = "ro", + .clear = "RW", + .ro_bit = true, + }, { + .mask = L_PTE_XN, + .val = L_PTE_XN, + .set = "NX", + .clear = "x ", + .nx_bit = true, + }, { + .mask = L_PTE_SHARED, + .val = L_PTE_SHARED, + .set = "SHD", + .clear = " ", + }, { + .mask = L_PTE_MT_MASK, + .val = L_PTE_MT_UNCACHED, + .set = "SO/UNCACHED", + }, { + .mask = L_PTE_MT_MASK, + .val = L_PTE_MT_BUFFERABLE, + .set = "MEM/BUFFERABLE/WC", + }, { + .mask = L_PTE_MT_MASK, + .val = L_PTE_MT_WRITETHROUGH, + .set = "MEM/CACHED/WT", + }, { + .mask = L_PTE_MT_MASK, + .val = L_PTE_MT_WRITEBACK, + .set = "MEM/CACHED/WBRA", +#ifndef CONFIG_ARM_LPAE + }, { + .mask = L_PTE_MT_MASK, + .val = L_PTE_MT_MINICACHE, + .set = "MEM/MINICACHE", +#endif + }, { + .mask = L_PTE_MT_MASK, + .val = L_PTE_MT_WRITEALLOC, + .set = "MEM/CACHED/WBWA", + }, { + .mask = L_PTE_MT_MASK, + .val = L_PTE_MT_DEV_SHARED, + .set = "DEV/SHARED", +#ifndef CONFIG_ARM_LPAE + }, { + .mask = L_PTE_MT_MASK, + .val = L_PTE_MT_DEV_NONSHARED, + .set = "DEV/NONSHARED", +#endif + }, { + .mask = L_PTE_MT_MASK, + .val = L_PTE_MT_DEV_WC, + .set = "DEV/WC", + }, { + .mask = L_PTE_MT_MASK, + .val = L_PTE_MT_DEV_CACHED, + .set = "DEV/CACHED", + }, +}; + +static const struct prot_bits section_bits[] = { +#ifdef CONFIG_ARM_LPAE + { + .mask = PMD_SECT_USER, + .val = PMD_SECT_USER, + .set = "USR", + }, { + .mask = L_PMD_SECT_RDONLY | PMD_SECT_AP2, + .val = L_PMD_SECT_RDONLY | PMD_SECT_AP2, + .set = "ro", + .clear = "RW", + .ro_bit = true, +#elif __LINUX_ARM_ARCH__ >= 6 + { + .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, + .val = PMD_SECT_APX | PMD_SECT_AP_WRITE, + .set = " ro", + .ro_bit = true, + }, { + .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, + .val = PMD_SECT_AP_WRITE, + .set = " RW", + }, { + .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, + .val = PMD_SECT_AP_READ, + .set = "USR ro", + }, { + .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, + .val = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, + .set = "USR RW", +#else /* ARMv4/ARMv5 */ + /* These are approximate */ + { + .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, + .val = 0, + .set = " ro", + .ro_bit = true, + }, { + .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, + .val = PMD_SECT_AP_WRITE, + .set = " RW", + }, { + .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, + .val = PMD_SECT_AP_READ, + .set = "USR ro", + }, { + .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, + .val = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, + .set = "USR RW", +#endif + }, { + .mask = PMD_SECT_XN, + .val = PMD_SECT_XN, + .set = "NX", + .clear = "x ", + .nx_bit = true, + }, { + .mask = PMD_SECT_S, + .val = PMD_SECT_S, + .set = "SHD", + .clear = " ", + }, +}; + +struct pg_level { + const char *name; + const struct prot_bits *bits; + size_t num; + u64 mask; + const struct prot_bits *ro_bit; + const struct prot_bits *nx_bit; +}; + +static struct pg_level pg_level[] = { + { + }, { /* pgd */ + }, { /* p4d */ + }, { /* pud */ + }, { /* pmd */ + .name = (CONFIG_PGTABLE_LEVELS > 2) ? "PMD" : "PGD", + .bits = section_bits, + .num = ARRAY_SIZE(section_bits), + }, { /* pte */ + .name = "PTE", + .bits = pte_bits, + .num = ARRAY_SIZE(pte_bits), + }, +}; + +static void dump_prot(struct pg_state *st, const struct prot_bits *bits, size_t num) +{ + unsigned i; + + for (i = 0; i < num; i++, bits++) { + const char *s; + + if ((st->current_prot & bits->mask) == bits->val) + s = bits->set; + else + s = bits->clear; + + if (s) + pt_dump_seq_printf(st->seq, " %s", s); + } +} + +static void note_prot_wx(struct pg_state *st, unsigned long addr) +{ + if (!st->check_wx) + return; + if ((st->current_prot & pg_level[st->level].ro_bit->mask) == + pg_level[st->level].ro_bit->val) + return; + if ((st->current_prot & pg_level[st->level].nx_bit->mask) == + pg_level[st->level].nx_bit->val) + return; + + WARN_ONCE(1, "arm/mm: Found insecure W+X mapping at address %pS\n", + (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, const char *domain) +{ + static const char units[] = "KMGTPE"; + u64 prot = val & pg_level[level].mask; + + if (!st->level) { + st->level = level; + st->current_prot = prot; + st->current_domain = domain; + pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); + } else if (prot != st->current_prot || level != st->level || + domain != st->current_domain || + addr >= st->marker[1].start_address) { + const char *unit = units; + unsigned long delta; + + if (st->current_prot) { + note_prot_wx(st, addr); + pt_dump_seq_printf(st->seq, "0x%08lx-0x%08lx ", + st->start_address, addr); + + delta = (addr - st->start_address) >> 10; + while (!(delta & 1023) && unit[1]) { + delta >>= 10; + unit++; + } + pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit, + pg_level[st->level].name); + if (st->current_domain) + pt_dump_seq_printf(st->seq, " %s", + st->current_domain); + if (pg_level[st->level].bits) + dump_prot(st, pg_level[st->level].bits, pg_level[st->level].num); + pt_dump_seq_printf(st->seq, "\n"); + } + + if (addr >= st->marker[1].start_address) { + st->marker++; + pt_dump_seq_printf(st->seq, "---[ %s ]---\n", + st->marker->name); + } + st->start_address = addr; + st->current_prot = prot; + st->current_domain = domain; + st->level = level; + } +} + +static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start, + const char *domain) +{ + pte_t *pte = pte_offset_kernel(pmd, 0); + unsigned long addr; + unsigned i; + + for (i = 0; i < PTRS_PER_PTE; i++, pte++) { + addr = start + i * PAGE_SIZE; + note_page(st, addr, 5, pte_val(*pte), domain); + } +} + +static const char *get_domain_name(pmd_t *pmd) +{ +#ifndef CONFIG_ARM_LPAE + switch (pmd_val(*pmd) & PMD_DOMAIN_MASK) { + case PMD_DOMAIN(DOMAIN_KERNEL): + return "KERNEL "; + case PMD_DOMAIN(DOMAIN_USER): + return "USER "; + case PMD_DOMAIN(DOMAIN_IO): + return "IO "; + case PMD_DOMAIN(DOMAIN_VECTORS): + return "VECTORS"; + default: + return "unknown"; + } +#endif + return NULL; +} + +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 i; + const char *domain; + + for (i = 0; i < PTRS_PER_PMD; i++, pmd++) { + addr = start + i * PMD_SIZE; + domain = get_domain_name(pmd); + if (pmd_none(*pmd) || pmd_leaf(*pmd) || !pmd_present(*pmd)) + note_page(st, addr, 4, pmd_val(*pmd), domain); + else + walk_pte(st, pmd, addr, domain); + + if (SECTION_SIZE < PMD_SIZE && pmd_leaf(pmd[1])) { + addr += SECTION_SIZE; + pmd++; + domain = get_domain_name(pmd); + note_page(st, addr, 4, pmd_val(*pmd), domain); + } + } +} + +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 i; + + for (i = 0; i < PTRS_PER_PUD; i++, pud++) { + addr = start + i * PUD_SIZE; + if (!pud_none(*pud)) { + walk_pmd(st, pud, addr); + } else { + note_page(st, addr, 3, pud_val(*pud), NULL); + } + } +} + +static void walk_p4d(struct pg_state *st, pgd_t *pgd, unsigned long start) +{ + p4d_t *p4d = p4d_offset(pgd, 0); + unsigned long addr; + unsigned i; + + for (i = 0; i < PTRS_PER_P4D; i++, p4d++) { + addr = start + i * P4D_SIZE; + if (!p4d_none(*p4d)) { + walk_pud(st, p4d, addr); + } else { + note_page(st, addr, 2, p4d_val(*p4d), NULL); + } + } +} + +static void walk_pgd(struct pg_state *st, struct mm_struct *mm, + unsigned long start) +{ + pgd_t *pgd = pgd_offset(mm, 0UL); + unsigned i; + unsigned long addr; + + for (i = 0; i < PTRS_PER_PGD; i++, pgd++) { + addr = start + i * PGDIR_SIZE; + if (!pgd_none(*pgd)) { + walk_p4d(st, pgd, addr); + } else { + note_page(st, addr, 1, pgd_val(*pgd), NULL); + } + } +} + +void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info) +{ + struct pg_state st = { + .seq = m, + .marker = info->markers, + .check_wx = false, + }; + + walk_pgd(&st, info->mm, info->base_addr); + note_page(&st, 0, 0, 0, NULL); +} + +static void __init ptdump_initialize(void) +{ + unsigned i, j; + + for (i = 0; i < ARRAY_SIZE(pg_level); i++) + if (pg_level[i].bits) + for (j = 0; j < pg_level[i].num; j++) { + pg_level[i].mask |= pg_level[i].bits[j].mask; + if (pg_level[i].bits[j].ro_bit) + pg_level[i].ro_bit = &pg_level[i].bits[j]; + if (pg_level[i].bits[j].nx_bit) + pg_level[i].nx_bit = &pg_level[i].bits[j]; + } +#ifdef CONFIG_KASAN + address_markers[4].start_address = VMALLOC_START; +#else + address_markers[2].start_address = VMALLOC_START; +#endif +} + +static struct ptdump_info kernel_ptdump_info = { + .mm = &init_mm, + .markers = address_markers, + .base_addr = 0, +}; + +void ptdump_check_wx(void) +{ + struct pg_state st = { + .seq = NULL, + .marker = (struct addr_marker[]) { + { 0, NULL}, + { -1, NULL}, + }, + .check_wx = true, + }; + + walk_pgd(&st, &init_mm, 0); + note_page(&st, 0, 0, 0, NULL); + 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"); +} + +static int __init ptdump_init(void) +{ + ptdump_initialize(); + ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables"); + return 0; +} +__initcall(ptdump_init); 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