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/sample.c | 134 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 134 insertions(+) create mode 100644 tools/perf/util/sample.c (limited to 'tools/perf/util/sample.c') diff --git a/tools/perf/util/sample.c b/tools/perf/util/sample.c new file mode 100644 index 000000000..bccc19e2a --- /dev/null +++ b/tools/perf/util/sample.c @@ -0,0 +1,134 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include "sample.h" + +#include +#include + +#include +#include + +#include "../../arch/x86/include/asm/insn.h" +#include "debug.h" +#include "evsel.h" +#include "thread.h" + +#ifndef EM_CSKY +#define EM_CSKY 252 +#endif +#ifndef EM_LOONGARCH +#define EM_LOONGARCH 258 +#endif + +void perf_sample__init(struct perf_sample *sample, bool all) +{ + if (all) { + memset(sample, 0, sizeof(*sample)); + } else { + sample->evsel = NULL; + sample->user_regs = NULL; + sample->intr_regs = NULL; + sample->merged_callchain = false; + sample->callchain = NULL; + } +} + +void perf_sample__exit(struct perf_sample *sample) +{ + evsel__put(sample->evsel); + sample->evsel = NULL; + zfree(&sample->user_regs); + zfree(&sample->intr_regs); + if (sample->merged_callchain) { + zfree(&sample->callchain); + sample->merged_callchain = false; + } +} + +struct regs_dump *perf_sample__user_regs(struct perf_sample *sample) +{ + if (!sample->user_regs) { + sample->user_regs = zalloc(sizeof(*sample->user_regs)); + if (!sample->user_regs) + pr_err("Failure to allocate sample user_regs"); + } + return sample->user_regs; +} + + +struct regs_dump *perf_sample__intr_regs(struct perf_sample *sample) +{ + if (!sample->intr_regs) { + sample->intr_regs = zalloc(sizeof(*sample->intr_regs)); + if (!sample->intr_regs) + pr_err("Failure to allocate sample intr_regs"); + } + return sample->intr_regs; +} + +static int elf_machine_max_instruction_length(uint16_t e_machine) +{ + switch (e_machine) { + /* Fixed 4-byte (32-bit) architectures */ + case EM_AARCH64: + case EM_PPC: + case EM_PPC64: + case EM_MIPS: + case EM_SPARC: + case EM_SPARCV9: + case EM_ALPHA: + case EM_LOONGARCH: + case EM_PARISC: + case EM_SH: + return 4; + + /* Variable length or mixed-mode architectures */ + case EM_ARM: /* Variable due to Thumb/Thumb-2 */ + case EM_RISCV: /* Variable due to Compressed (C) extension */ + case EM_CSKY: /* Variable (16 or 32 bit) */ + case EM_ARC: /* Variable (ARCompact) */ + return 4; + case EM_S390: /* Variable (2, 4, or 6 bytes) */ + return 6; + case EM_68K: + return 10; + case EM_386: + case EM_X86_64: + return 15; + case EM_XTENSA: /* Variable (FLIX) */ + return 16; + default: + return MAX_INSN; + } +} + +void perf_sample__fetch_insn(struct perf_sample *sample, + struct thread *thread, + struct machine *machine) +{ + int ret, len; + bool is64bit = false; + uint16_t e_machine; + + if (!sample->ip || sample->insn_len != 0) + return; + + e_machine = thread__e_machine(thread, machine, /*e_flags=*/NULL); + len = elf_machine_max_instruction_length(e_machine); + len = thread__memcpy(thread, machine, sample->insn, + sample->ip, len, + &is64bit); + if (len <= 0) + return; + + sample->insn_len = len; + + if (e_machine == EM_386 || e_machine == EM_X86_64) { + /* Refine the x86 instruction length with the decoder. */ + struct insn insn; + + ret = insn_decode(&insn, sample->insn, len, + is64bit ? INSN_MODE_64 : INSN_MODE_32); + if (ret >= 0 && insn.length <= len) + sample->insn_len = insn.length; + } +} -- cgit v1.3.1