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/pgd.c | 209 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 209 insertions(+) create mode 100644 arch/arm/mm/pgd.c (limited to 'arch/arm/mm/pgd.c') diff --git a/arch/arm/mm/pgd.c b/arch/arm/mm/pgd.c new file mode 100644 index 000000000..447945836 --- /dev/null +++ b/arch/arm/mm/pgd.c @@ -0,0 +1,209 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/arch/arm/mm/pgd.c + * + * Copyright (C) 1998-2005 Russell King + */ +#include +#include +#include +#include + +#include +#include +#include +#include + +#include "mm.h" + +#ifdef CONFIG_ARM_LPAE +#define _pgd_alloc(mm) kmalloc_objs(pgd_t, PTRS_PER_PGD, GFP_KERNEL | __GFP_ZERO) +#define _pgd_free(mm, pgd) kfree(pgd) +#else +#define _pgd_alloc(mm) __pgd_alloc(mm, 2) +#define _pgd_free(mm, pgd) __pgd_free(mm, pgd) +#endif + +/* + * need to get a 16k page for level 1 + */ +pgd_t *pgd_alloc(struct mm_struct *mm) +{ + pgd_t *new_pgd, *init_pgd; + p4d_t *new_p4d, *init_p4d; + pud_t *new_pud, *init_pud; + pmd_t *new_pmd, *init_pmd; + pte_t *new_pte, *init_pte; + + new_pgd = _pgd_alloc(mm); + if (!new_pgd) + goto no_pgd; + + /* + * Copy over the kernel and IO PGD entries + */ + init_pgd = pgd_offset_k(0); + memcpy(new_pgd + USER_PTRS_PER_PGD, init_pgd + USER_PTRS_PER_PGD, + (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t)); + + clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t)); + +#ifdef CONFIG_ARM_LPAE + /* + * Allocate PMD table for modules and pkmap mappings. + */ + new_p4d = p4d_alloc(mm, new_pgd + pgd_index(MODULES_VADDR), + MODULES_VADDR); + if (!new_p4d) + goto no_p4d; + + new_pud = pud_alloc(mm, new_p4d, MODULES_VADDR); + if (!new_pud) + goto no_pud; + + new_pmd = pmd_alloc(mm, new_pud, 0); + if (!new_pmd) + goto no_pmd; +#ifdef CONFIG_KASAN + /* + * Copy PMD table for KASAN shadow mappings. + */ + init_pgd = pgd_offset_k(TASK_SIZE); + init_p4d = p4d_offset(init_pgd, TASK_SIZE); + init_pud = pud_offset(init_p4d, TASK_SIZE); + init_pmd = pmd_offset(init_pud, TASK_SIZE); + new_pmd = pmd_offset(new_pud, TASK_SIZE); + memcpy(new_pmd, init_pmd, + (pmd_index(MODULES_VADDR) - pmd_index(TASK_SIZE)) + * sizeof(pmd_t)); + clean_dcache_area(new_pmd, PTRS_PER_PMD * sizeof(pmd_t)); +#endif /* CONFIG_KASAN */ +#endif /* CONFIG_LPAE */ + + if (!vectors_high()) { + /* + * On ARM, first page must always be allocated since it + * contains the machine vectors. The vectors are always high + * with LPAE. + */ + new_p4d = p4d_alloc(mm, new_pgd, 0); + if (!new_p4d) + goto no_p4d; + + new_pud = pud_alloc(mm, new_p4d, 0); + if (!new_pud) + goto no_pud; + + new_pmd = pmd_alloc(mm, new_pud, 0); + if (!new_pmd) + goto no_pmd; + + new_pte = pte_alloc_map(mm, new_pmd, 0); + if (!new_pte) + goto no_pte; + +#ifndef CONFIG_ARM_LPAE + /* + * Modify the PTE pointer to have the correct domain. This + * needs to be the vectors domain to avoid the low vectors + * being unmapped. + */ + pmd_val(*new_pmd) &= ~PMD_DOMAIN_MASK; + pmd_val(*new_pmd) |= PMD_DOMAIN(DOMAIN_VECTORS); +#endif + + init_p4d = p4d_offset(init_pgd, 0); + init_pud = pud_offset(init_p4d, 0); + init_pmd = pmd_offset(init_pud, 0); + init_pte = pte_offset_map(init_pmd, 0); + set_pte_ext(new_pte + 0, init_pte[0], 0); + set_pte_ext(new_pte + 1, init_pte[1], 0); + pte_unmap(init_pte); + pte_unmap(new_pte); + } + + return new_pgd; + +no_pte: + pmd_free(mm, new_pmd); + mm_dec_nr_pmds(mm); +no_pmd: + pud_free(mm, new_pud); +no_pud: + p4d_free(mm, new_p4d); +no_p4d: + _pgd_free(mm, new_pgd); +no_pgd: + return NULL; +} + +void pgd_free(struct mm_struct *mm, pgd_t *pgd_base) +{ + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + pmd_t *pmd; + pgtable_t pte; + + if (!pgd_base) + return; + + pgd = pgd_base + pgd_index(0); + if (pgd_none_or_clear_bad(pgd)) + goto no_pgd; + + p4d = p4d_offset(pgd, 0); + if (p4d_none_or_clear_bad(p4d)) + goto no_p4d; + + pud = pud_offset(p4d, 0); + if (pud_none_or_clear_bad(pud)) + goto no_pud; + + pmd = pmd_offset(pud, 0); + if (pmd_none_or_clear_bad(pmd)) + goto no_pmd; + + pte = pmd_pgtable(*pmd); + pmd_clear(pmd); + pte_free(mm, pte); + mm_dec_nr_ptes(mm); +no_pmd: + pud_clear(pud); + pmd_free(mm, pmd); + mm_dec_nr_pmds(mm); +no_pud: + p4d_clear(p4d); + pud_free(mm, pud); +no_p4d: + pgd_clear(pgd); + p4d_free(mm, p4d); +no_pgd: +#ifdef CONFIG_ARM_LPAE + /* + * Free modules/pkmap or identity pmd tables. + */ + for (pgd = pgd_base; pgd < pgd_base + PTRS_PER_PGD; pgd++) { + if (pgd_none_or_clear_bad(pgd)) + continue; + if (pgd_val(*pgd) & L_PGD_SWAPPER) + continue; + p4d = p4d_offset(pgd, 0); + if (p4d_none_or_clear_bad(p4d)) + continue; + pud = pud_offset(p4d, 0); + if (pud_none_or_clear_bad(pud)) + continue; + pmd = pmd_offset(pud, 0); + pud_clear(pud); + pmd_free(mm, pmd); + mm_dec_nr_pmds(mm); + p4d_clear(p4d); + pud_free(mm, pud); + mm_dec_nr_puds(mm); + pgd_clear(pgd); + p4d_free(mm, p4d); + } +#endif + _pgd_free(mm, pgd_base); +} -- cgit v1.3.1