From 9cc63f8bcd560c760d0b12e15bba8f81c86237cf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 14 Aug 2026 15:43:51 -0700 Subject: Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEAD Changes: Make expedited grace periods expedite normal RCU callbacks Miscellaneous fixes: * Improve diagnostic output with character task states. * Mark accesses to inform KCSAN of concurrency design. * Move from kmalloc() to kmalloc_obj(). * Documentation updates. * Improve handling of RCU deferred quiescent states. * Clean up unused function arguments and structure fields. * Reduce show_rcu_gp_kthreads() stack space. Tasks RCU updates: * Clean up after SRCU re-implementation of Tasks Trace RCU. * Mark accesses to inform KCSAN of concurrency design. * Add ->lazy_timer status to diagnostic output. * Remove an unnecessary memory barrier. * Fix a data race, courtesy of KCSAN. * Documentation updates. * Convert cond_resched_tasks_rcu_qs() from macro to static inline function. SRCU updates: * Add Rust helpers for SRCU. * Avoid losing queued work at cleanup_srcu_struct() time. Torture-test updates: * Preparation work for immediate RCU priority deboosting. * Test RCU readers from real interrupt handlers (as opposed to softirq). * Simplify code through use of cpumask_next_wrap(). * Improve diagnostic output with character task states. * Add rcutorture.nwriters parameter to allow lightweight stall testing, and rcutorture.stall_only to make doing so easier. * Test an RCU Tasks Trace grace period implying an RCU grace period. * Make RCU Tasks Trace torturing track reader batches. * Fix a data race, courtesy of KCSAN. * Plug a shuffle_tmp_mask memory leak on kthread spawn failure. --- lib/extable.c | 118 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 118 insertions(+) create mode 100644 lib/extable.c (limited to 'lib/extable.c') diff --git a/lib/extable.c b/lib/extable.c new file mode 100644 index 000000000..9c9f40bd2 --- /dev/null +++ b/lib/extable.c @@ -0,0 +1,118 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c. + * + * Copyright (C) 2004 Paul Mackerras, IBM Corp. + */ + +#include +#include +#include +#include +#include +#include + +#ifndef ARCH_HAS_RELATIVE_EXTABLE +#define ex_to_insn(x) ((x)->insn) +#else +static inline unsigned long ex_to_insn(const struct exception_table_entry *x) +{ + return (unsigned long)&x->insn + x->insn; +} +#endif + +#ifndef ARCH_HAS_RELATIVE_EXTABLE +#define swap_ex NULL +#else +static void swap_ex(void *a, void *b, int size) +{ + struct exception_table_entry *x = a, *y = b, tmp; + int delta = b - a; + + tmp = *x; + x->insn = y->insn + delta; + y->insn = tmp.insn - delta; + +#ifdef swap_ex_entry_fixup + swap_ex_entry_fixup(x, y, tmp, delta); +#else + x->fixup = y->fixup + delta; + y->fixup = tmp.fixup - delta; +#endif +} +#endif /* ARCH_HAS_RELATIVE_EXTABLE */ + +/* + * The exception table needs to be sorted so that the binary + * search that we use to find entries in it works properly. + * This is used both for the kernel exception table and for + * the exception tables of modules that get loaded. + */ +static int cmp_ex_sort(const void *a, const void *b) +{ + const struct exception_table_entry *x = a, *y = b; + + /* avoid overflow */ + if (ex_to_insn(x) > ex_to_insn(y)) + return 1; + if (ex_to_insn(x) < ex_to_insn(y)) + return -1; + return 0; +} + +void sort_extable(struct exception_table_entry *start, + struct exception_table_entry *finish) +{ + sort(start, finish - start, sizeof(struct exception_table_entry), + cmp_ex_sort, swap_ex); +} + +#ifdef CONFIG_MODULES +/* + * If the exception table is sorted, any referring to the module init + * will be at the beginning or the end. + */ +void trim_init_extable(struct module *m) +{ + /*trim the beginning*/ + while (m->num_exentries && + within_module_init(ex_to_insn(&m->extable[0]), m)) { + m->extable++; + m->num_exentries--; + } + /*trim the end*/ + while (m->num_exentries && + within_module_init(ex_to_insn(&m->extable[m->num_exentries - 1]), + m)) + m->num_exentries--; +} +#endif /* CONFIG_MODULES */ + +static int cmp_ex_search(const void *key, const void *elt) +{ + const struct exception_table_entry *_elt = elt; + unsigned long _key = *(unsigned long *)key; + + /* avoid overflow */ + if (_key > ex_to_insn(_elt)) + return 1; + if (_key < ex_to_insn(_elt)) + return -1; + return 0; +} + +/* + * Search one exception table for an entry corresponding to the + * given instruction address, and return the address of the entry, + * or NULL if none is found. + * We use a binary search, and thus we assume that the table is + * already sorted. + */ +const struct exception_table_entry * +search_extable(const struct exception_table_entry *base, + const size_t num, + unsigned long value) +{ + return bsearch(&value, base, num, + sizeof(struct exception_table_entry), cmp_ex_search); +} -- cgit v1.3.1