bf589e3296
This is in preparation for changes in the cpu buffer implementation. Signed-off-by: Robert Richter <robert.richter@amd.com>
118 lines
2.7 KiB
C
118 lines
2.7 KiB
C
/**
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* @file cpu_buffer.h
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*
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* @remark Copyright 2002 OProfile authors
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* @remark Read the file COPYING
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*
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* @author John Levon <levon@movementarian.org>
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*/
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#ifndef OPROFILE_CPU_BUFFER_H
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#define OPROFILE_CPU_BUFFER_H
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#include <linux/types.h>
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#include <linux/spinlock.h>
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#include <linux/workqueue.h>
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#include <linux/cache.h>
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#include <linux/sched.h>
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struct task_struct;
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int alloc_cpu_buffers(void);
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void free_cpu_buffers(void);
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void start_cpu_work(void);
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void end_cpu_work(void);
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/* CPU buffer is composed of such entries (which are
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* also used for context switch notes)
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*/
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struct op_sample {
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unsigned long eip;
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unsigned long event;
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};
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struct oprofile_cpu_buffer {
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volatile unsigned long head_pos;
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volatile unsigned long tail_pos;
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unsigned long buffer_size;
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struct task_struct *last_task;
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int last_is_kernel;
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int tracing;
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struct op_sample *buffer;
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unsigned long sample_received;
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unsigned long sample_lost_overflow;
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unsigned long backtrace_aborted;
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unsigned long sample_invalid_eip;
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int cpu;
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struct delayed_work work;
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};
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DECLARE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);
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void cpu_buffer_reset(struct oprofile_cpu_buffer *cpu_buf);
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static inline
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struct op_sample *cpu_buffer_write_entry(struct oprofile_cpu_buffer *cpu_buf)
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{
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return &cpu_buf->buffer[cpu_buf->head_pos];
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}
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static inline
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void cpu_buffer_write_commit(struct oprofile_cpu_buffer *b)
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{
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unsigned long new_head = b->head_pos + 1;
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/*
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* Ensure anything written to the slot before we increment is
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* visible
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*/
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wmb();
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if (new_head < b->buffer_size)
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b->head_pos = new_head;
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else
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b->head_pos = 0;
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}
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static inline
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struct op_sample *cpu_buffer_read_entry(struct oprofile_cpu_buffer *cpu_buf)
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{
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return &cpu_buf->buffer[cpu_buf->tail_pos];
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}
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/* "acquire" as many cpu buffer slots as we can */
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static inline
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unsigned long cpu_buffer_entries(struct oprofile_cpu_buffer *b)
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{
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unsigned long head = b->head_pos;
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unsigned long tail = b->tail_pos;
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/*
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* Subtle. This resets the persistent last_task
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* and in_kernel values used for switching notes.
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* BUT, there is a small window between reading
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* head_pos, and this call, that means samples
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* can appear at the new head position, but not
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* be prefixed with the notes for switching
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* kernel mode or a task switch. This small hole
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* can lead to mis-attribution or samples where
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* we don't know if it's in the kernel or not,
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* at the start of an event buffer.
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*/
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cpu_buffer_reset(b);
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if (head >= tail)
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return head - tail;
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return head + (b->buffer_size - tail);
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}
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/* transient events for the CPU buffer -> event buffer */
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#define CPU_IS_KERNEL 1
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#define CPU_TRACE_BEGIN 2
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#define IBS_FETCH_BEGIN 3
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#define IBS_OP_BEGIN 4
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#endif /* OPROFILE_CPU_BUFFER_H */
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