mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-11 17:36:49 +07:00
6eaaa5d57e
Impact: api and pipe waiting change Currently, the waiting used in tracing_read_pipe() is done through a 100 msecs schedule_timeout() loop which periodically check if there are traces on the buffer. This can cause small latencies for programs which are reading the incoming events. This patch makes the reader waiting for the trace_wait waitqueue except for few tracers such as the sched and functions tracers which might be already hold the runqueue lock while waking up the reader. This is performed through a new callback wait_pipe() on struct tracer. If none is implemented on a specific tracer, the default waiting for trace_wait queue is attached. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
405 lines
8.2 KiB
C
405 lines
8.2 KiB
C
/*
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* ring buffer based function tracer
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*
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
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*
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* Based on code from the latency_tracer, that is:
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*
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* Copyright (C) 2004-2006 Ingo Molnar
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* Copyright (C) 2004 William Lee Irwin III
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*/
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#include <linux/ring_buffer.h>
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#include <linux/debugfs.h>
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#include <linux/uaccess.h>
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#include <linux/ftrace.h>
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#include <linux/fs.h>
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#include "trace.h"
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/* function tracing enabled */
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static int ftrace_function_enabled;
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static struct trace_array *func_trace;
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static void tracing_start_function_trace(void);
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static void tracing_stop_function_trace(void);
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static int function_trace_init(struct trace_array *tr)
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{
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func_trace = tr;
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tr->cpu = get_cpu();
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put_cpu();
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tracing_start_cmdline_record();
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tracing_start_function_trace();
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return 0;
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}
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static void function_trace_reset(struct trace_array *tr)
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{
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tracing_stop_function_trace();
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tracing_stop_cmdline_record();
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}
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static void function_trace_start(struct trace_array *tr)
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{
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tracing_reset_online_cpus(tr);
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}
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static void
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function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
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{
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struct trace_array *tr = func_trace;
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struct trace_array_cpu *data;
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unsigned long flags;
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long disabled;
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int cpu, resched;
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int pc;
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if (unlikely(!ftrace_function_enabled))
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return;
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pc = preempt_count();
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resched = ftrace_preempt_disable();
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local_save_flags(flags);
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cpu = raw_smp_processor_id();
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data = tr->data[cpu];
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disabled = atomic_inc_return(&data->disabled);
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if (likely(disabled == 1))
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trace_function(tr, ip, parent_ip, flags, pc);
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atomic_dec(&data->disabled);
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ftrace_preempt_enable(resched);
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}
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static void
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function_trace_call(unsigned long ip, unsigned long parent_ip)
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{
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struct trace_array *tr = func_trace;
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struct trace_array_cpu *data;
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unsigned long flags;
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long disabled;
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int cpu;
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int pc;
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if (unlikely(!ftrace_function_enabled))
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return;
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/*
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* Need to use raw, since this must be called before the
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* recursive protection is performed.
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*/
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local_irq_save(flags);
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cpu = raw_smp_processor_id();
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data = tr->data[cpu];
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disabled = atomic_inc_return(&data->disabled);
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if (likely(disabled == 1)) {
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pc = preempt_count();
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trace_function(tr, ip, parent_ip, flags, pc);
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}
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atomic_dec(&data->disabled);
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local_irq_restore(flags);
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}
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static void
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function_stack_trace_call(unsigned long ip, unsigned long parent_ip)
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{
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struct trace_array *tr = func_trace;
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struct trace_array_cpu *data;
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unsigned long flags;
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long disabled;
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int cpu;
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int pc;
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if (unlikely(!ftrace_function_enabled))
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return;
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/*
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* Need to use raw, since this must be called before the
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* recursive protection is performed.
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*/
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local_irq_save(flags);
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cpu = raw_smp_processor_id();
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data = tr->data[cpu];
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disabled = atomic_inc_return(&data->disabled);
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if (likely(disabled == 1)) {
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pc = preempt_count();
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trace_function(tr, ip, parent_ip, flags, pc);
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/*
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* skip over 5 funcs:
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* __ftrace_trace_stack,
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* __trace_stack,
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* function_stack_trace_call
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* ftrace_list_func
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* ftrace_call
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*/
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__trace_stack(tr, flags, 5, pc);
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}
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atomic_dec(&data->disabled);
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local_irq_restore(flags);
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}
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static struct ftrace_ops trace_ops __read_mostly =
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{
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.func = function_trace_call,
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};
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static struct ftrace_ops trace_stack_ops __read_mostly =
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{
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.func = function_stack_trace_call,
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};
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/* Our two options */
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enum {
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TRACE_FUNC_OPT_STACK = 0x1,
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};
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static struct tracer_opt func_opts[] = {
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#ifdef CONFIG_STACKTRACE
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{ TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
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#endif
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{ } /* Always set a last empty entry */
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};
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static struct tracer_flags func_flags = {
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.val = 0, /* By default: all flags disabled */
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.opts = func_opts
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};
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static void tracing_start_function_trace(void)
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{
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ftrace_function_enabled = 0;
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if (trace_flags & TRACE_ITER_PREEMPTONLY)
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trace_ops.func = function_trace_call_preempt_only;
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else
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trace_ops.func = function_trace_call;
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if (func_flags.val & TRACE_FUNC_OPT_STACK)
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register_ftrace_function(&trace_stack_ops);
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else
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register_ftrace_function(&trace_ops);
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ftrace_function_enabled = 1;
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}
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static void tracing_stop_function_trace(void)
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{
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ftrace_function_enabled = 0;
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/* OK if they are not registered */
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unregister_ftrace_function(&trace_stack_ops);
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unregister_ftrace_function(&trace_ops);
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}
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static int func_set_flag(u32 old_flags, u32 bit, int set)
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{
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if (bit == TRACE_FUNC_OPT_STACK) {
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/* do nothing if already set */
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if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
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return 0;
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if (set) {
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unregister_ftrace_function(&trace_ops);
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register_ftrace_function(&trace_stack_ops);
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} else {
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unregister_ftrace_function(&trace_stack_ops);
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register_ftrace_function(&trace_ops);
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}
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return 0;
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}
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return -EINVAL;
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}
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static struct tracer function_trace __read_mostly =
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{
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.name = "function",
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.init = function_trace_init,
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.reset = function_trace_reset,
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.start = function_trace_start,
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.wait_pipe = poll_wait_pipe,
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.flags = &func_flags,
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.set_flag = func_set_flag,
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#ifdef CONFIG_FTRACE_SELFTEST
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.selftest = trace_selftest_startup_function,
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#endif
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};
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#ifdef CONFIG_DYNAMIC_FTRACE
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static void
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ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
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{
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long *count = (long *)data;
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if (tracing_is_on())
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return;
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if (!*count)
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return;
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if (*count != -1)
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(*count)--;
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tracing_on();
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}
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static void
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ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
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{
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long *count = (long *)data;
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if (!tracing_is_on())
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return;
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if (!*count)
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return;
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if (*count != -1)
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(*count)--;
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tracing_off();
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}
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static int
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ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
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struct ftrace_probe_ops *ops, void *data);
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static struct ftrace_probe_ops traceon_probe_ops = {
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.func = ftrace_traceon,
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.print = ftrace_trace_onoff_print,
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};
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static struct ftrace_probe_ops traceoff_probe_ops = {
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.func = ftrace_traceoff,
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.print = ftrace_trace_onoff_print,
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};
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static int
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ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
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struct ftrace_probe_ops *ops, void *data)
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{
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char str[KSYM_SYMBOL_LEN];
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long count = (long)data;
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kallsyms_lookup(ip, NULL, NULL, NULL, str);
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seq_printf(m, "%s:", str);
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if (ops == &traceon_probe_ops)
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seq_printf(m, "traceon");
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else
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seq_printf(m, "traceoff");
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if (count == -1)
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seq_printf(m, ":unlimited\n");
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else
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seq_printf(m, ":count=%ld", count);
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seq_putc(m, '\n');
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return 0;
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}
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static int
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ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
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{
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struct ftrace_probe_ops *ops;
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/* we register both traceon and traceoff to this callback */
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if (strcmp(cmd, "traceon") == 0)
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ops = &traceon_probe_ops;
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else
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ops = &traceoff_probe_ops;
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unregister_ftrace_function_probe_func(glob, ops);
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return 0;
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}
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static int
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ftrace_trace_onoff_callback(char *glob, char *cmd, char *param, int enable)
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{
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struct ftrace_probe_ops *ops;
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void *count = (void *)-1;
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char *number;
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int ret;
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/* hash funcs only work with set_ftrace_filter */
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if (!enable)
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return -EINVAL;
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if (glob[0] == '!')
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return ftrace_trace_onoff_unreg(glob+1, cmd, param);
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/* we register both traceon and traceoff to this callback */
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if (strcmp(cmd, "traceon") == 0)
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ops = &traceon_probe_ops;
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else
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ops = &traceoff_probe_ops;
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if (!param)
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goto out_reg;
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number = strsep(¶m, ":");
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if (!strlen(number))
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goto out_reg;
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/*
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* We use the callback data field (which is a pointer)
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* as our counter.
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*/
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ret = strict_strtoul(number, 0, (unsigned long *)&count);
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if (ret)
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return ret;
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out_reg:
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ret = register_ftrace_function_probe(glob, ops, count);
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return ret;
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}
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static struct ftrace_func_command ftrace_traceon_cmd = {
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.name = "traceon",
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.func = ftrace_trace_onoff_callback,
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};
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static struct ftrace_func_command ftrace_traceoff_cmd = {
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.name = "traceoff",
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.func = ftrace_trace_onoff_callback,
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};
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static int __init init_func_cmd_traceon(void)
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{
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int ret;
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ret = register_ftrace_command(&ftrace_traceoff_cmd);
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if (ret)
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return ret;
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ret = register_ftrace_command(&ftrace_traceon_cmd);
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if (ret)
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unregister_ftrace_command(&ftrace_traceoff_cmd);
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return ret;
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}
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#else
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static inline int init_func_cmd_traceon(void)
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{
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return 0;
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}
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#endif /* CONFIG_DYNAMIC_FTRACE */
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static __init int init_function_trace(void)
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{
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init_func_cmd_traceon();
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return register_tracer(&function_trace);
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}
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device_initcall(init_function_trace);
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