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 --- tools/perf/util/lock-contention.c | 143 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 143 insertions(+) create mode 100644 tools/perf/util/lock-contention.c (limited to 'tools/perf/util/lock-contention.c') diff --git a/tools/perf/util/lock-contention.c b/tools/perf/util/lock-contention.c new file mode 100644 index 000000000..119a7206f --- /dev/null +++ b/tools/perf/util/lock-contention.c @@ -0,0 +1,143 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "debug.h" +#include "env.h" +#include "lock-contention.h" +#include "machine.h" +#include "symbol.h" + +#include +#include + +#include +#include + +#define __lockhashfn(key) hash_long((unsigned long)key, LOCKHASH_BITS) +#define lockhashentry(key) (lockhash_table + __lockhashfn((key))) + +struct callstack_filter { + struct list_head list; + char name[]; +}; + +static LIST_HEAD(callstack_filters); +struct hlist_head *lockhash_table; + +int parse_call_stack(const struct option *opt __maybe_unused, const char *str, + int unset __maybe_unused) +{ + char *s, *tmp, *tok; + int ret = 0; + + s = strdup(str); + if (s == NULL) + return -1; + + for (tok = strtok_r(s, ", ", &tmp); tok; tok = strtok_r(NULL, ", ", &tmp)) { + struct callstack_filter *entry; + + entry = malloc(sizeof(*entry) + strlen(tok) + 1); + if (entry == NULL) { + pr_err("Memory allocation failure\n"); + free(s); + return -1; + } + + strcpy(entry->name, tok); + list_add_tail(&entry->list, &callstack_filters); + } + + free(s); + return ret; +} + +bool needs_callstack(void) +{ + return !list_empty(&callstack_filters); +} + +struct lock_stat *lock_stat_find(u64 addr) +{ + struct hlist_head *entry = lockhashentry(addr); + struct lock_stat *ret; + + hlist_for_each_entry(ret, entry, hash_entry) { + if (ret->addr == addr) + return ret; + } + return NULL; +} + +struct lock_stat *lock_stat_findnew(u64 addr, const char *name, int flags) +{ + struct hlist_head *entry = lockhashentry(addr); + struct lock_stat *ret, *new; + + hlist_for_each_entry(ret, entry, hash_entry) { + if (ret->addr == addr) + return ret; + } + + new = zalloc(sizeof(struct lock_stat)); + if (!new) + goto alloc_failed; + + new->addr = addr; + new->name = strdup(name); + if (!new->name) { + free(new); + goto alloc_failed; + } + + new->flags = flags; + new->wait_time_min = ULLONG_MAX; + + hlist_add_head(&new->hash_entry, entry); + return new; + +alloc_failed: + pr_err("memory allocation failed\n"); + return NULL; +} + +bool match_callstack_filter(struct machine *machine, u64 *callstack, int max_stack_depth) +{ + struct map *kmap; + struct symbol *sym; + u64 ip; + uint16_t e_machine = perf_env__e_machine(machine->env, /*e_flags=*/NULL); + bool is_powerpc = e_machine == EM_PPC64 || e_machine == EM_PPC; + + if (list_empty(&callstack_filters)) + return true; + + for (int i = 0; i < max_stack_depth; i++) { + struct callstack_filter *filter; + + /* + * In powerpc, the callchain saved by kernel always includes + * first three entries as the NIP (next instruction pointer), + * LR (link register), and the contents of LR save area in the + * second stack frame. In certain scenarios its possible to have + * invalid kernel instruction addresses in either LR or the second + * stack frame's LR. In that case, kernel will store that address as + * zero. + * + * The below check will continue to look into callstack, + * incase first or second callstack index entry has 0 + * address for powerpc. + */ + if (!callstack || (!callstack[i] && (!is_powerpc || (i != 1 && i != 2)))) + break; + + ip = callstack[i]; + sym = machine__find_kernel_symbol(machine, ip, &kmap); + if (sym == NULL) + continue; + + list_for_each_entry(filter, &callstack_filters, list) { + if (strstr(sym->name, filter->name)) + return true; + } + } + return false; +} -- cgit v1.3.1