ftrace_event.h

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#ifndef _LINUX_FTRACE_EVENT_H
#define _LINUX_FTRACE_EVENT_H

#include <linux/ring_buffer.h>
#include <linux/trace_seq.h>
#include <linux/percpu.h>
#include <linux/hardirq.h>
#include <linux/perf_event.h>

struct trace_array;
struct tracer;
struct dentry;

struct trace_print_flags {
    unsigned long       mask;
    const char      *name;
};

struct trace_print_flags_u64 {
    unsigned long long  mask;
    const char      *name;
};

const char *ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
                   unsigned long flags,
                   const struct trace_print_flags *flag_array);

const char *ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
                     const struct trace_print_flags *symbol_array);

#if BITS_PER_LONG == 32
const char *ftrace_print_symbols_seq_u64(struct trace_seq *p,
                     unsigned long long val,
                     const struct trace_print_flags_u64
                                 *symbol_array);
#endif

const char *ftrace_print_hex_seq(struct trace_seq *p,
                 const unsigned char *buf, int len);

/*
 * The trace entry - the most basic unit of tracing. This is what
 * is printed in the end as a single line in the trace output, such as:
 *
 *     bash-15816 [01]   235.197585: idle_cpu <- irq_enter
 */
struct trace_entry {
    unsigned short      type;
    unsigned char       flags;
    unsigned char       preempt_count;
    int         pid;
    int         padding;
};

#define FTRACE_MAX_EVENT                        \
    ((1 << (sizeof(((struct trace_entry *)0)->type) * 8)) - 1)

/*
 * Trace iterator - used by printout routines who present trace
 * results to users and which routines might sleep, etc:
 */
struct trace_iterator {
    struct trace_array  *tr;
    struct tracer       *trace;
    void            *private;
    int         cpu_file;
    struct mutex        mutex;
    struct ring_buffer_iter **buffer_iter;
    unsigned long       iter_flags;

    /* trace_seq for __print_flags() and __print_symbolic() etc. */
    struct trace_seq    tmp_seq;

    /* The below is zeroed out in pipe_read */
    struct trace_seq    seq;
    struct trace_entry  *ent;
    unsigned long       lost_events;
    int         leftover;
    int         ent_size;
    int         cpu;
    u64         ts;

    loff_t          pos;
    long            idx;

    cpumask_var_t       started;
};


struct trace_event;

typedef enum print_line_t (*trace_print_func)(struct trace_iterator *iter,
                      int flags, struct trace_event *event);

struct trace_event_functions {
    trace_print_func    trace;
    trace_print_func    raw;
    trace_print_func    hex;
    trace_print_func    binary;
};

struct trace_event {
    struct hlist_node       node;
    struct list_head        list;
    int             type;
    struct trace_event_functions    *funcs;
};

extern int register_ftrace_event(struct trace_event *event);
extern int unregister_ftrace_event(struct trace_event *event);

/* Return values for print_line callback */
enum print_line_t {
    TRACE_TYPE_PARTIAL_LINE = 0,    /* Retry after flushing the seq */
    TRACE_TYPE_HANDLED  = 1,
    TRACE_TYPE_UNHANDLED    = 2,    /* Relay to other output functions */
    TRACE_TYPE_NO_CONSUME   = 3 /* Handled but ask to not consume */
};

void tracing_generic_entry_update(struct trace_entry *entry,
                  unsigned long flags,
                  int pc);
struct ring_buffer_event *
trace_current_buffer_lock_reserve(struct ring_buffer **current_buffer,
                  int type, unsigned long len,
                  unsigned long flags, int pc);
void trace_current_buffer_unlock_commit(struct ring_buffer *buffer,
                    struct ring_buffer_event *event,
                    unsigned long flags, int pc);
void trace_nowake_buffer_unlock_commit(struct ring_buffer *buffer,
                       struct ring_buffer_event *event,
                    unsigned long flags, int pc);
void trace_nowake_buffer_unlock_commit_regs(struct ring_buffer *buffer,
                        struct ring_buffer_event *event,
                        unsigned long flags, int pc,
                        struct pt_regs *regs);
void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
                     struct ring_buffer_event *event);

void tracing_record_cmdline(struct task_struct *tsk);

struct event_filter;

enum trace_reg {
    TRACE_REG_REGISTER,
    TRACE_REG_UNREGISTER,
#ifdef CONFIG_PERF_EVENTS
    TRACE_REG_PERF_REGISTER,
    TRACE_REG_PERF_UNREGISTER,
    TRACE_REG_PERF_OPEN,
    TRACE_REG_PERF_CLOSE,
    TRACE_REG_PERF_ADD,
    TRACE_REG_PERF_DEL,
#endif
};

struct ftrace_event_call;

struct ftrace_event_class {
    char            *system;
    void            *probe;
#ifdef CONFIG_PERF_EVENTS
    void            *perf_probe;
#endif
    int         (*reg)(struct ftrace_event_call *event,
                       enum trace_reg type, void *data);
    int         (*define_fields)(struct ftrace_event_call *);
    struct list_head    *(*get_fields)(struct ftrace_event_call *);
    struct list_head    fields;
    int         (*raw_init)(struct ftrace_event_call *);
};

extern int ftrace_event_reg(struct ftrace_event_call *event,
                enum trace_reg type, void *data);

enum {
    TRACE_EVENT_FL_ENABLED_BIT,
    TRACE_EVENT_FL_FILTERED_BIT,
    TRACE_EVENT_FL_RECORDED_CMD_BIT,
    TRACE_EVENT_FL_CAP_ANY_BIT,
    TRACE_EVENT_FL_NO_SET_FILTER_BIT,
    TRACE_EVENT_FL_IGNORE_ENABLE_BIT,
};

enum {
    TRACE_EVENT_FL_ENABLED      = (1 << TRACE_EVENT_FL_ENABLED_BIT),
    TRACE_EVENT_FL_FILTERED     = (1 << TRACE_EVENT_FL_FILTERED_BIT),
    TRACE_EVENT_FL_RECORDED_CMD = (1 << TRACE_EVENT_FL_RECORDED_CMD_BIT),
    TRACE_EVENT_FL_CAP_ANY      = (1 << TRACE_EVENT_FL_CAP_ANY_BIT),
    TRACE_EVENT_FL_NO_SET_FILTER    = (1 << TRACE_EVENT_FL_NO_SET_FILTER_BIT),
    TRACE_EVENT_FL_IGNORE_ENABLE    = (1 << TRACE_EVENT_FL_IGNORE_ENABLE_BIT),
};

struct ftrace_event_call {
    struct list_head    list;
    struct ftrace_event_class *class;
    char            *name;
    struct dentry       *dir;
    struct trace_event  event;
    const char      *print_fmt;
    struct event_filter *filter;
    void            *mod;
    void            *data;

    /*
     * 32 bit flags:
     *   bit 1:     enabled
     *   bit 2:     filter_active
     *   bit 3:     enabled cmd record
     *   bit 4:     allow trace by non root (cap any)
     *   bit 5:     failed to apply filter
     *   bit 6:     ftrace internal event (do not enable)
     *
     * Changes to flags must hold the event_mutex.
     *
     * Note: Reads of flags do not hold the event_mutex since
     * they occur in critical sections. But the way flags
     * is currently used, these changes do no affect the code
     * except that when a change is made, it may have a slight
     * delay in propagating the changes to other CPUs due to
     * caching and such.
     */
    unsigned int        flags;

#ifdef CONFIG_PERF_EVENTS
    int             perf_refcount;
    struct hlist_head __percpu  *perf_events;
#endif
};

#define __TRACE_EVENT_FLAGS(name, value)                \
    static int __init trace_init_flags_##name(void)         \
    {                               \
        event_##name.flags = value;             \
        return 0;                       \
    }                               \
    early_initcall(trace_init_flags_##name);

#define PERF_MAX_TRACE_SIZE 2048

#define MAX_FILTER_STR_VAL  256 /* Should handle KSYM_SYMBOL_LEN */

extern void destroy_preds(struct ftrace_event_call *call);
extern int filter_match_preds(struct event_filter *filter, void *rec);
extern int filter_current_check_discard(struct ring_buffer *buffer,
                    struct ftrace_event_call *call,
                    void *rec,
                    struct ring_buffer_event *event);

enum {
    FILTER_OTHER = 0,
    FILTER_STATIC_STRING,
    FILTER_DYN_STRING,
    FILTER_PTR_STRING,
    FILTER_TRACE_FN,
};

#define EVENT_STORAGE_SIZE 128
extern struct mutex event_storage_mutex;
extern char event_storage[EVENT_STORAGE_SIZE];

extern int trace_event_raw_init(struct ftrace_event_call *call);
extern int trace_define_field(struct ftrace_event_call *call, const char *type,
                  const char *name, int offset, int size,
                  int is_signed, int filter_type);
extern int trace_add_event_call(struct ftrace_event_call *call);
extern void trace_remove_event_call(struct ftrace_event_call *call);

#define is_signed_type(type)    (((type)(-1)) < 0)

int trace_set_clr_event(const char *system, const char *event, int set);

/*
 * The double __builtin_constant_p is because gcc will give us an error
 * if we try to allocate the static variable to fmt if it is not a
 * constant. Even with the outer if statement optimizing out.
 */
#define event_trace_printk(ip, fmt, args...)                \
do {                                    \
    __trace_printk_check_format(fmt, ##args);           \
    tracing_record_cmdline(current);                \
    if (__builtin_constant_p(fmt)) {                \
        static const char *trace_printk_fmt         \
          __attribute__((section("__trace_printk_fmt"))) =  \
            __builtin_constant_p(fmt) ? fmt : NULL;     \
                                    \
        __trace_bprintk(ip, trace_printk_fmt, ##args);      \
    } else                              \
        __trace_printk(ip, fmt, ##args);            \
} while (0)

#ifdef CONFIG_PERF_EVENTS
struct perf_event;

DECLARE_PER_CPU(struct pt_regs, perf_trace_regs);

extern int  perf_trace_init(struct perf_event *event);
extern void perf_trace_destroy(struct perf_event *event);
extern int  perf_trace_add(struct perf_event *event, int flags);
extern void perf_trace_del(struct perf_event *event, int flags);
extern int  ftrace_profile_set_filter(struct perf_event *event, int event_id,
                     char *filter_str);
extern void ftrace_profile_free_filter(struct perf_event *event);
extern void *perf_trace_buf_prepare(int size, unsigned short type,
                    struct pt_regs *regs, int *rctxp);

static inline void
perf_trace_buf_submit(void *raw_data, int size, int rctx, u64 addr,
               u64 count, struct pt_regs *regs, void *head,
               struct task_struct *task)
{
    perf_tp_event(addr, count, raw_data, size, regs, head, rctx, task);
}
#endif

#endif /* _LINUX_FTRACE_EVENT_H */