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/tsc.c | 142 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 142 insertions(+) create mode 100644 tools/perf/util/tsc.c (limited to 'tools/perf/util/tsc.c') diff --git a/tools/perf/util/tsc.c b/tools/perf/util/tsc.c new file mode 100644 index 000000000..ebf289bf6 --- /dev/null +++ b/tools/perf/util/tsc.c @@ -0,0 +1,142 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include + +#include +#include +#include +#include + +#include + +#include "event.h" +#include "synthetic-events.h" +#include "debug.h" +#include "tsc.h" + +u64 perf_time_to_tsc(u64 ns, struct perf_tsc_conversion *tc) +{ + u64 t, quot, rem; + + t = ns - tc->time_zero; + quot = t / tc->time_mult; + rem = t % tc->time_mult; + return (quot << tc->time_shift) + + (rem << tc->time_shift) / tc->time_mult; +} + +u64 tsc_to_perf_time(u64 cyc, struct perf_tsc_conversion *tc) +{ + u64 quot, rem; + + if (tc->cap_user_time_short) + cyc = tc->time_cycles + + ((cyc - tc->time_cycles) & tc->time_mask); + + quot = cyc >> tc->time_shift; + rem = cyc & (((u64)1 << tc->time_shift) - 1); + return tc->time_zero + quot * tc->time_mult + + ((rem * tc->time_mult) >> tc->time_shift); +} + +int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc, + struct perf_tsc_conversion *tc) +{ + u32 seq; + int i = 0; + + while (1) { + seq = pc->lock; + rmb(); + tc->time_mult = pc->time_mult; + tc->time_shift = pc->time_shift; + tc->time_zero = pc->time_zero; + tc->time_cycles = pc->time_cycles; + tc->time_mask = pc->time_mask; + tc->cap_user_time_zero = pc->cap_user_time_zero; + tc->cap_user_time_short = pc->cap_user_time_short; + rmb(); + if (pc->lock == seq && !(seq & 1)) + break; + if (++i > 10000) { + pr_debug("failed to get perf_event_mmap_page lock\n"); + return -EINVAL; + } + } + + if (!tc->cap_user_time_zero) + return -EOPNOTSUPP; + + return 0; +} + +int perf_event__synth_time_conv(const struct perf_event_mmap_page *pc, + const struct perf_tool *tool, + perf_event__handler_t process, + struct machine *machine) +{ + union perf_event event = { + .time_conv = { + .header = { + .type = PERF_RECORD_TIME_CONV, + .size = sizeof(struct perf_record_time_conv), + }, + }, + }; + struct perf_tsc_conversion tc; + int err; + + if (!pc) + return 0; + err = perf_read_tsc_conversion(pc, &tc); + if (err == -EOPNOTSUPP) + return 0; + if (err) + return err; + + pr_debug2("Synthesizing TSC conversion information\n"); + + event.time_conv.time_mult = tc.time_mult; + event.time_conv.time_shift = tc.time_shift; + event.time_conv.time_zero = tc.time_zero; + event.time_conv.time_cycles = tc.time_cycles; + event.time_conv.time_mask = tc.time_mask; + event.time_conv.cap_user_time_zero = tc.cap_user_time_zero; + event.time_conv.cap_user_time_short = tc.cap_user_time_short; + + return process(tool, &event, NULL, machine); +} + +u64 __weak rdtsc(void) +{ + return 0; +} + +size_t perf_event__fprintf_time_conv(union perf_event *event, FILE *fp) +{ + struct perf_record_time_conv *tc = (struct perf_record_time_conv *)event; + size_t ret; + + ret = fprintf(fp, "\n... Time Shift %" PRI_lu64 "\n", tc->time_shift); + ret += fprintf(fp, "... Time Multiplier %" PRI_lu64 "\n", tc->time_mult); + ret += fprintf(fp, "... Time Zero %" PRI_lu64 "\n", tc->time_zero); + + /* + * The event TIME_CONV was extended for the fields from "time_cycles" + * when supported cap_user_time_short, for backward compatibility, + * prints the extended fields only if they are contained in the event. + */ + if (event_contains(*tc, cap_user_time_short)) { + ret += fprintf(fp, "... Time Cycles %" PRI_lu64 "\n", + tc->time_cycles); + ret += fprintf(fp, "... Time Mask %#" PRI_lx64 "\n", + tc->time_mask); + ret += fprintf(fp, "... Cap Time Zero %" PRId32 "\n", + tc->cap_user_time_zero); + ret += fprintf(fp, "... Cap Time Short %" PRId32 "\n", + tc->cap_user_time_short); + } + + return ret; +} -- cgit v1.3.1