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1bc191051d
- New user_events interface. User space can register an event with the kernel describing the format of the event. Then it will receive a byte in a page mapping that it can check against. A privileged task can then enable that event like any other event, which will change the mapped byte to true, telling the user space application to start writing the event to the tracing buffer. - Add new "ftrace_boot_snapshot" kernel command line parameter. When set, the tracing buffer will be saved in the snapshot buffer at boot up when the kernel hands things over to user space. This will keep the traces that happened at boot up available even if user space boot up has tracing as well. - Have TRACE_EVENT_ENUM() also update trace event field type descriptions. Thus if a static array defines its size with an enum, the user space trace event parsers can still know how to parse that array. - Add new TRACE_CUSTOM_EVENT() macro. This acts the same as the TRACE_EVENT() macro, but will attach to an existing tracepoint. This will make one tracepoint be able to trace different content and not be stuck at only what the original TRACE_EVENT() macro exports. - Fixes to tracing error logging. - Better saving of cmdlines to PIDs when tracing (use the wakeup events for mapping). -----BEGIN PGP SIGNATURE----- iIoEABYIADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCYjiO3RQccm9zdGVkdEBn b29kbWlzLm9yZwAKCRAp5XQQmuv6qhQzAQDtek5p80p/zkMGymm14wSH6qq0NdgN Kv7fTBwEewUa0gD/UCOVLw4Oj+JtHQhCa3sCGZopmRv0BT1+4UQANqosKQY= =Au08 -----END PGP SIGNATURE----- Merge tag 'trace-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: - New user_events interface. User space can register an event with the kernel describing the format of the event. Then it will receive a byte in a page mapping that it can check against. A privileged task can then enable that event like any other event, which will change the mapped byte to true, telling the user space application to start writing the event to the tracing buffer. - Add new "ftrace_boot_snapshot" kernel command line parameter. When set, the tracing buffer will be saved in the snapshot buffer at boot up when the kernel hands things over to user space. This will keep the traces that happened at boot up available even if user space boot up has tracing as well. - Have TRACE_EVENT_ENUM() also update trace event field type descriptions. Thus if a static array defines its size with an enum, the user space trace event parsers can still know how to parse that array. - Add new TRACE_CUSTOM_EVENT() macro. This acts the same as the TRACE_EVENT() macro, but will attach to an existing tracepoint. This will make one tracepoint be able to trace different content and not be stuck at only what the original TRACE_EVENT() macro exports. - Fixes to tracing error logging. - Better saving of cmdlines to PIDs when tracing (use the wakeup events for mapping). * tag 'trace-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (30 commits) tracing: Have type enum modifications copy the strings user_events: Add trace event call as root for low permission cases tracing/user_events: Use alloc_pages instead of kzalloc() for register pages tracing: Add snapshot at end of kernel boot up tracing: Have TRACE_DEFINE_ENUM affect trace event types as well tracing: Fix strncpy warning in trace_events_synth.c user_events: Prevent dyn_event delete racing with ioctl add/delete tracing: Add TRACE_CUSTOM_EVENT() macro tracing: Move the defines to create TRACE_EVENTS into their own files tracing: Add sample code for custom trace events tracing: Allow custom events to be added to the tracefs directory tracing: Fix last_cmd_set() string management in histogram code user_events: Fix potential uninitialized pointer while parsing field tracing: Fix allocation of last_cmd in last_cmd_set() user_events: Add documentation file user_events: Add sample code for typical usage user_events: Add self-test for validator boundaries user_events: Add self-test for perf_event integration user_events: Add self-test for dynamic_events integration user_events: Add self-test for ftrace integration ...
151 lines
3.1 KiB
C
151 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* trace context switch
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*
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* Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
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*
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*/
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#include <linux/module.h>
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#include <linux/kallsyms.h>
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#include <linux/uaccess.h>
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#include <linux/ftrace.h>
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#include <trace/events/sched.h>
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#include "trace.h"
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#define RECORD_CMDLINE 1
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#define RECORD_TGID 2
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static int sched_cmdline_ref;
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static int sched_tgid_ref;
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static DEFINE_MUTEX(sched_register_mutex);
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static void
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probe_sched_switch(void *ignore, bool preempt,
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unsigned int prev_state,
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struct task_struct *prev, struct task_struct *next)
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{
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int flags;
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flags = (RECORD_TGID * !!sched_tgid_ref) +
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(RECORD_CMDLINE * !!sched_cmdline_ref);
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if (!flags)
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return;
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tracing_record_taskinfo_sched_switch(prev, next, flags);
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}
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static void
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probe_sched_wakeup(void *ignore, struct task_struct *wakee)
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{
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int flags;
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flags = (RECORD_TGID * !!sched_tgid_ref) +
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(RECORD_CMDLINE * !!sched_cmdline_ref);
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if (!flags)
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return;
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tracing_record_taskinfo_sched_switch(current, wakee, flags);
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}
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static int tracing_sched_register(void)
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{
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int ret;
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ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
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if (ret) {
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pr_info("wakeup trace: Couldn't activate tracepoint"
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" probe to kernel_sched_wakeup\n");
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return ret;
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}
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ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
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if (ret) {
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pr_info("wakeup trace: Couldn't activate tracepoint"
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" probe to kernel_sched_wakeup_new\n");
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goto fail_deprobe;
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}
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ret = register_trace_sched_switch(probe_sched_switch, NULL);
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if (ret) {
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pr_info("sched trace: Couldn't activate tracepoint"
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" probe to kernel_sched_switch\n");
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goto fail_deprobe_wake_new;
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}
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return ret;
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fail_deprobe_wake_new:
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unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
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fail_deprobe:
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unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
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return ret;
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}
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static void tracing_sched_unregister(void)
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{
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unregister_trace_sched_switch(probe_sched_switch, NULL);
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unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
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unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
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}
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static void tracing_start_sched_switch(int ops)
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{
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bool sched_register;
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mutex_lock(&sched_register_mutex);
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sched_register = (!sched_cmdline_ref && !sched_tgid_ref);
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switch (ops) {
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case RECORD_CMDLINE:
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sched_cmdline_ref++;
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break;
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case RECORD_TGID:
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sched_tgid_ref++;
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break;
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}
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if (sched_register && (sched_cmdline_ref || sched_tgid_ref))
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tracing_sched_register();
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mutex_unlock(&sched_register_mutex);
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}
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static void tracing_stop_sched_switch(int ops)
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{
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mutex_lock(&sched_register_mutex);
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switch (ops) {
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case RECORD_CMDLINE:
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sched_cmdline_ref--;
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break;
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case RECORD_TGID:
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sched_tgid_ref--;
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break;
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}
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if (!sched_cmdline_ref && !sched_tgid_ref)
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tracing_sched_unregister();
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mutex_unlock(&sched_register_mutex);
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}
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void tracing_start_cmdline_record(void)
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{
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tracing_start_sched_switch(RECORD_CMDLINE);
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}
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void tracing_stop_cmdline_record(void)
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{
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tracing_stop_sched_switch(RECORD_CMDLINE);
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}
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void tracing_start_tgid_record(void)
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{
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tracing_start_sched_switch(RECORD_TGID);
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}
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void tracing_stop_tgid_record(void)
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{
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tracing_stop_sched_switch(RECORD_TGID);
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}
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