forked from Minki/linux
9c2136be08
Commitfa2c3254d7(sched/tracing: Don't re-read p->state when emitting sched_switch event, 2022-01-20) added a new prev_state argument to the sched_switch tracepoint, before the prev task_struct pointer. This reordering of arguments broke BPF programs that use the raw tracepoint (e.g. tp_btf programs). The type of the second argument has changed and existing programs that assume a task_struct* argument (e.g. for bpf_task_storage access) will now fail to verify. If we instead append the new argument to the end, all existing programs would continue to work and can conditionally extract the prev_state argument on supported kernel versions. Fixes:fa2c3254d7(sched/tracing: Don't re-read p->state when emitting sched_switch event, 2022-01-20) Signed-off-by: Delyan Kratunov <delyank@fb.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> Link: https://lkml.kernel.org/r/c8a6930dfdd58a4a5755fc01732675472979732b.camel@fb.com
151 lines
3.1 KiB
C
151 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* trace context switch
|
|
*
|
|
* Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
|
|
*
|
|
*/
|
|
#include <linux/module.h>
|
|
#include <linux/kallsyms.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/ftrace.h>
|
|
#include <trace/events/sched.h>
|
|
|
|
#include "trace.h"
|
|
|
|
#define RECORD_CMDLINE 1
|
|
#define RECORD_TGID 2
|
|
|
|
static int sched_cmdline_ref;
|
|
static int sched_tgid_ref;
|
|
static DEFINE_MUTEX(sched_register_mutex);
|
|
|
|
static void
|
|
probe_sched_switch(void *ignore, bool preempt,
|
|
struct task_struct *prev, struct task_struct *next,
|
|
unsigned int prev_state)
|
|
{
|
|
int flags;
|
|
|
|
flags = (RECORD_TGID * !!sched_tgid_ref) +
|
|
(RECORD_CMDLINE * !!sched_cmdline_ref);
|
|
|
|
if (!flags)
|
|
return;
|
|
tracing_record_taskinfo_sched_switch(prev, next, flags);
|
|
}
|
|
|
|
static void
|
|
probe_sched_wakeup(void *ignore, struct task_struct *wakee)
|
|
{
|
|
int flags;
|
|
|
|
flags = (RECORD_TGID * !!sched_tgid_ref) +
|
|
(RECORD_CMDLINE * !!sched_cmdline_ref);
|
|
|
|
if (!flags)
|
|
return;
|
|
tracing_record_taskinfo_sched_switch(current, wakee, flags);
|
|
}
|
|
|
|
static int tracing_sched_register(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
|
|
if (ret) {
|
|
pr_info("wakeup trace: Couldn't activate tracepoint"
|
|
" probe to kernel_sched_wakeup\n");
|
|
return ret;
|
|
}
|
|
|
|
ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
|
|
if (ret) {
|
|
pr_info("wakeup trace: Couldn't activate tracepoint"
|
|
" probe to kernel_sched_wakeup_new\n");
|
|
goto fail_deprobe;
|
|
}
|
|
|
|
ret = register_trace_sched_switch(probe_sched_switch, NULL);
|
|
if (ret) {
|
|
pr_info("sched trace: Couldn't activate tracepoint"
|
|
" probe to kernel_sched_switch\n");
|
|
goto fail_deprobe_wake_new;
|
|
}
|
|
|
|
return ret;
|
|
fail_deprobe_wake_new:
|
|
unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
|
|
fail_deprobe:
|
|
unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
|
|
return ret;
|
|
}
|
|
|
|
static void tracing_sched_unregister(void)
|
|
{
|
|
unregister_trace_sched_switch(probe_sched_switch, NULL);
|
|
unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
|
|
unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
|
|
}
|
|
|
|
static void tracing_start_sched_switch(int ops)
|
|
{
|
|
bool sched_register;
|
|
|
|
mutex_lock(&sched_register_mutex);
|
|
sched_register = (!sched_cmdline_ref && !sched_tgid_ref);
|
|
|
|
switch (ops) {
|
|
case RECORD_CMDLINE:
|
|
sched_cmdline_ref++;
|
|
break;
|
|
|
|
case RECORD_TGID:
|
|
sched_tgid_ref++;
|
|
break;
|
|
}
|
|
|
|
if (sched_register && (sched_cmdline_ref || sched_tgid_ref))
|
|
tracing_sched_register();
|
|
mutex_unlock(&sched_register_mutex);
|
|
}
|
|
|
|
static void tracing_stop_sched_switch(int ops)
|
|
{
|
|
mutex_lock(&sched_register_mutex);
|
|
|
|
switch (ops) {
|
|
case RECORD_CMDLINE:
|
|
sched_cmdline_ref--;
|
|
break;
|
|
|
|
case RECORD_TGID:
|
|
sched_tgid_ref--;
|
|
break;
|
|
}
|
|
|
|
if (!sched_cmdline_ref && !sched_tgid_ref)
|
|
tracing_sched_unregister();
|
|
mutex_unlock(&sched_register_mutex);
|
|
}
|
|
|
|
void tracing_start_cmdline_record(void)
|
|
{
|
|
tracing_start_sched_switch(RECORD_CMDLINE);
|
|
}
|
|
|
|
void tracing_stop_cmdline_record(void)
|
|
{
|
|
tracing_stop_sched_switch(RECORD_CMDLINE);
|
|
}
|
|
|
|
void tracing_start_tgid_record(void)
|
|
{
|
|
tracing_start_sched_switch(RECORD_TGID);
|
|
}
|
|
|
|
void tracing_stop_tgid_record(void)
|
|
{
|
|
tracing_stop_sched_switch(RECORD_TGID);
|
|
}
|