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linux/kernel/trace/trace_probe.h
Steven Rostedt (Google) b61edd5774 eprobes: Remove redundant event type information 
Currently, the event probes save the type of the event they are attached
to when recording the event. For example:

  # echo 'e:switch sched/sched_switch prev_state=$prev_state prev_prio=$prev_prio next_pid=$next_pid next_prio=$next_prio' > dynamic_events
  # cat events/eprobes/switch/format

 name: switch
 ID: 1717
 format:
        field:unsigned short common_type;       offset:0;       size:2; signed:0;
        field:unsigned char common_flags;       offset:2;       size:1; signed:0;
        field:unsigned char common_preempt_count;       offset:3;       size:1; signed:0;
        field:int common_pid;   offset:4;       size:4; signed:1;

        field:unsigned int __probe_type;        offset:8;       size:4; signed:0;
        field:u64 prev_state;   offset:12;      size:8; signed:0;
        field:u64 prev_prio;    offset:20;      size:8; signed:0;
        field:u64 next_pid;     offset:28;      size:8; signed:0;
        field:u64 next_prio;    offset:36;      size:8; signed:0;

 print fmt: "(%u) prev_state=0x%Lx prev_prio=0x%Lx next_pid=0x%Lx next_prio=0x%Lx", REC->__probe_type, REC->prev_state, REC->prev_prio, REC->next_pid, REC->next_prio

The __probe_type adds 4 bytes to every event.

One of the reasons for creating eprobes is to limit what is traced in an
event to be able to limit what is written into the ring buffer. Having
this redundant 4 bytes to every event takes away from this.

The event that is recorded can be retrieved from the event probe itself,
that is available when the trace is happening. For user space tools, it
could simply read the dynamic_event file to find the event they are for.
So there is really no reason to write this information into the ring
buffer for every event.

Link: https://lkml.kernel.org/r/20220218190057.2f5a19a8@gandalf.local.home

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-02-25 12:07:01 -05:00

469 lines
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C
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// SPDX-License-Identifier: GPL-2.0
/*
* Common header file for probe-based Dynamic events.
*
* This code was copied from kernel/trace/trace_kprobe.h written by
* Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
*
* Updates to make this generic:
* Copyright (C) IBM Corporation, 2010-2011
* Author: Srikar Dronamraju
*/
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/tracefs.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/ptrace.h>
#include <linux/perf_event.h>
#include <linux/kprobes.h>
#include <linux/stringify.h>
#include <linux/limits.h>
#include <linux/uaccess.h>
#include <linux/bitops.h>
#include <asm/bitsperlong.h>
#include "trace.h"
#include "trace_output.h"
#define MAX_TRACE_ARGS 128
#define MAX_ARGSTR_LEN 63
#define MAX_ARRAY_LEN 64
#define MAX_ARG_NAME_LEN 32
#define MAX_STRING_SIZE PATH_MAX
/* Reserved field names */
#define FIELD_STRING_IP "__probe_ip"
#define FIELD_STRING_RETIP "__probe_ret_ip"
#define FIELD_STRING_FUNC "__probe_func"
#undef DEFINE_FIELD
#define DEFINE_FIELD(type, item, name, is_signed) \
do { \
ret = trace_define_field(event_call, #type, name, \
offsetof(typeof(field), item), \
sizeof(field.item), is_signed, \
FILTER_OTHER); \
if (ret) \
return ret; \
} while (0)
/* Flags for trace_probe */
#define TP_FLAG_TRACE 1
#define TP_FLAG_PROFILE 2
/* data_loc: data location, compatible with u32 */
#define make_data_loc(len, offs) \
(((u32)(len) << 16) | ((u32)(offs) & 0xffff))
#define get_loc_len(dl) ((u32)(dl) >> 16)
#define get_loc_offs(dl) ((u32)(dl) & 0xffff)
static nokprobe_inline void *get_loc_data(u32 *dl, void *ent)
{
return (u8 *)ent + get_loc_offs(*dl);
}
static nokprobe_inline u32 update_data_loc(u32 loc, int consumed)
{
u32 maxlen = get_loc_len(loc);
u32 offset = get_loc_offs(loc);
return make_data_loc(maxlen - consumed, offset + consumed);
}
/* Printing function type */
typedef int (*print_type_func_t)(struct trace_seq *, void *, void *);
enum fetch_op {
FETCH_OP_NOP = 0,
// Stage 1 (load) ops
FETCH_OP_REG, /* Register : .param = offset */
FETCH_OP_STACK, /* Stack : .param = index */
FETCH_OP_STACKP, /* Stack pointer */
FETCH_OP_RETVAL, /* Return value */
FETCH_OP_IMM, /* Immediate : .immediate */
FETCH_OP_COMM, /* Current comm */
FETCH_OP_ARG, /* Function argument : .param */
FETCH_OP_FOFFS, /* File offset: .immediate */
FETCH_OP_DATA, /* Allocated data: .data */
// Stage 2 (dereference) op
FETCH_OP_DEREF, /* Dereference: .offset */
FETCH_OP_UDEREF, /* User-space Dereference: .offset */
// Stage 3 (store) ops
FETCH_OP_ST_RAW, /* Raw: .size */
FETCH_OP_ST_MEM, /* Mem: .offset, .size */
FETCH_OP_ST_UMEM, /* Mem: .offset, .size */
FETCH_OP_ST_STRING, /* String: .offset, .size */
FETCH_OP_ST_USTRING, /* User String: .offset, .size */
// Stage 4 (modify) op
FETCH_OP_MOD_BF, /* Bitfield: .basesize, .lshift, .rshift */
// Stage 5 (loop) op
FETCH_OP_LP_ARRAY, /* Array: .param = loop count */
FETCH_OP_TP_ARG, /* Trace Point argument */
FETCH_OP_END,
FETCH_NOP_SYMBOL, /* Unresolved Symbol holder */
};
struct fetch_insn {
enum fetch_op op;
union {
unsigned int param;
struct {
unsigned int size;
int offset;
};
struct {
unsigned char basesize;
unsigned char lshift;
unsigned char rshift;
};
unsigned long immediate;
void *data;
};
};
/* fetch + deref*N + store + mod + end <= 16, this allows N=12, enough */
#define FETCH_INSN_MAX 16
#define FETCH_TOKEN_COMM (-ECOMM)
/* Fetch type information table */
struct fetch_type {
const char *name; /* Name of type */
size_t size; /* Byte size of type */
int is_signed; /* Signed flag */
print_type_func_t print; /* Print functions */
const char *fmt; /* Format string */
const char *fmttype; /* Name in format file */
};
/* For defining macros, define string/string_size types */
typedef u32 string;
typedef u32 string_size;
#define PRINT_TYPE_FUNC_NAME(type) print_type_##type
#define PRINT_TYPE_FMT_NAME(type) print_type_format_##type
/* Printing in basic type function template */
#define DECLARE_BASIC_PRINT_TYPE_FUNC(type) \
int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s, void *data, void *ent);\
extern const char PRINT_TYPE_FMT_NAME(type)[]
DECLARE_BASIC_PRINT_TYPE_FUNC(u8);
DECLARE_BASIC_PRINT_TYPE_FUNC(u16);
DECLARE_BASIC_PRINT_TYPE_FUNC(u32);
DECLARE_BASIC_PRINT_TYPE_FUNC(u64);
DECLARE_BASIC_PRINT_TYPE_FUNC(s8);
DECLARE_BASIC_PRINT_TYPE_FUNC(s16);
DECLARE_BASIC_PRINT_TYPE_FUNC(s32);
DECLARE_BASIC_PRINT_TYPE_FUNC(s64);
DECLARE_BASIC_PRINT_TYPE_FUNC(x8);
DECLARE_BASIC_PRINT_TYPE_FUNC(x16);
DECLARE_BASIC_PRINT_TYPE_FUNC(x32);
DECLARE_BASIC_PRINT_TYPE_FUNC(x64);
DECLARE_BASIC_PRINT_TYPE_FUNC(string);
DECLARE_BASIC_PRINT_TYPE_FUNC(symbol);
/* Default (unsigned long) fetch type */
#define __DEFAULT_FETCH_TYPE(t) x##t
#define _DEFAULT_FETCH_TYPE(t) __DEFAULT_FETCH_TYPE(t)
#define DEFAULT_FETCH_TYPE _DEFAULT_FETCH_TYPE(BITS_PER_LONG)
#define DEFAULT_FETCH_TYPE_STR __stringify(DEFAULT_FETCH_TYPE)
#define __ADDR_FETCH_TYPE(t) u##t
#define _ADDR_FETCH_TYPE(t) __ADDR_FETCH_TYPE(t)
#define ADDR_FETCH_TYPE _ADDR_FETCH_TYPE(BITS_PER_LONG)
#define __ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, _fmttype) \
{.name = _name, \
.size = _size, \
.is_signed = sign, \
.print = PRINT_TYPE_FUNC_NAME(ptype), \
.fmt = PRINT_TYPE_FMT_NAME(ptype), \
.fmttype = _fmttype, \
}
#define _ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, _fmttype) \
__ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, #_fmttype)
#define ASSIGN_FETCH_TYPE(ptype, ftype, sign) \
_ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, ptype)
/* If ptype is an alias of atype, use this macro (show atype in format) */
#define ASSIGN_FETCH_TYPE_ALIAS(ptype, atype, ftype, sign) \
_ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, atype)
#define ASSIGN_FETCH_TYPE_END {}
#define MAX_ARRAY_LEN 64
#ifdef CONFIG_KPROBE_EVENTS
bool trace_kprobe_on_func_entry(struct trace_event_call *call);
bool trace_kprobe_error_injectable(struct trace_event_call *call);
#else
static inline bool trace_kprobe_on_func_entry(struct trace_event_call *call)
{
return false;
}
static inline bool trace_kprobe_error_injectable(struct trace_event_call *call)
{
return false;
}
#endif /* CONFIG_KPROBE_EVENTS */
struct probe_arg {
struct fetch_insn *code;
bool dynamic;/* Dynamic array (string) is used */
unsigned int offset; /* Offset from argument entry */
unsigned int count; /* Array count */
const char *name; /* Name of this argument */
const char *comm; /* Command of this argument */
char *fmt; /* Format string if needed */
const struct fetch_type *type; /* Type of this argument */
};
struct trace_uprobe_filter {
rwlock_t rwlock;
int nr_systemwide;
struct list_head perf_events;
};
/* Event call and class holder */
struct trace_probe_event {
unsigned int flags; /* For TP_FLAG_* */
struct trace_event_class class;
struct trace_event_call call;
struct list_head files;
struct list_head probes;
struct trace_uprobe_filter filter[];
};
struct trace_probe {
struct list_head list;
struct trace_probe_event *event;
ssize_t size; /* trace entry size */
unsigned int nr_args;
struct probe_arg args[];
};
struct event_file_link {
struct trace_event_file *file;
struct list_head list;
};
static inline bool trace_probe_test_flag(struct trace_probe *tp,
unsigned int flag)
{
return !!(tp->event->flags & flag);
}
static inline void trace_probe_set_flag(struct trace_probe *tp,
unsigned int flag)
{
tp->event->flags |= flag;
}
static inline void trace_probe_clear_flag(struct trace_probe *tp,
unsigned int flag)
{
tp->event->flags &= ~flag;
}
static inline bool trace_probe_is_enabled(struct trace_probe *tp)
{
return trace_probe_test_flag(tp, TP_FLAG_TRACE | TP_FLAG_PROFILE);
}
static inline const char *trace_probe_name(struct trace_probe *tp)
{
return trace_event_name(&tp->event->call);
}
static inline const char *trace_probe_group_name(struct trace_probe *tp)
{
return tp->event->call.class->system;
}
static inline struct trace_event_call *
trace_probe_event_call(struct trace_probe *tp)
{
return &tp->event->call;
}
static inline struct trace_probe_event *
trace_probe_event_from_call(struct trace_event_call *event_call)
{
return container_of(event_call, struct trace_probe_event, call);
}
static inline struct trace_probe *
trace_probe_primary_from_call(struct trace_event_call *call)
{
struct trace_probe_event *tpe = trace_probe_event_from_call(call);
return list_first_entry(&tpe->probes, struct trace_probe, list);
}
static inline struct list_head *trace_probe_probe_list(struct trace_probe *tp)
{
return &tp->event->probes;
}
static inline bool trace_probe_has_sibling(struct trace_probe *tp)
{
struct list_head *list = trace_probe_probe_list(tp);
return !list_empty(list) && !list_is_singular(list);
}
static inline int trace_probe_unregister_event_call(struct trace_probe *tp)
{
/* tp->event is unregistered in trace_remove_event_call() */
return trace_remove_event_call(&tp->event->call);
}
static inline bool trace_probe_has_single_file(struct trace_probe *tp)
{
return !!list_is_singular(&tp->event->files);
}
int trace_probe_init(struct trace_probe *tp, const char *event,
const char *group, bool alloc_filter);
void trace_probe_cleanup(struct trace_probe *tp);
int trace_probe_append(struct trace_probe *tp, struct trace_probe *to);
void trace_probe_unlink(struct trace_probe *tp);
int trace_probe_register_event_call(struct trace_probe *tp);
int trace_probe_add_file(struct trace_probe *tp, struct trace_event_file *file);
int trace_probe_remove_file(struct trace_probe *tp,
struct trace_event_file *file);
struct event_file_link *trace_probe_get_file_link(struct trace_probe *tp,
struct trace_event_file *file);
int trace_probe_compare_arg_type(struct trace_probe *a, struct trace_probe *b);
bool trace_probe_match_command_args(struct trace_probe *tp,
int argc, const char **argv);
int trace_probe_create(const char *raw_command, int (*createfn)(int, const char **));
#define trace_probe_for_each_link(pos, tp) \
list_for_each_entry(pos, &(tp)->event->files, list)
#define trace_probe_for_each_link_rcu(pos, tp) \
list_for_each_entry_rcu(pos, &(tp)->event->files, list)
#define TPARG_FL_RETURN BIT(0)
#define TPARG_FL_KERNEL BIT(1)
#define TPARG_FL_FENTRY BIT(2)
#define TPARG_FL_TPOINT BIT(3)
#define TPARG_FL_MASK GENMASK(3, 0)
extern int traceprobe_parse_probe_arg(struct trace_probe *tp, int i,
const char *argv, unsigned int flags);
extern int traceprobe_update_arg(struct probe_arg *arg);
extern void traceprobe_free_probe_arg(struct probe_arg *arg);
extern int traceprobe_split_symbol_offset(char *symbol, long *offset);
int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
char *buf, int offset);
enum probe_print_type {
PROBE_PRINT_NORMAL,
PROBE_PRINT_RETURN,
PROBE_PRINT_EVENT,
};
extern int traceprobe_set_print_fmt(struct trace_probe *tp, enum probe_print_type ptype);
#ifdef CONFIG_PERF_EVENTS
extern struct trace_event_call *
create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
bool is_return);
extern void destroy_local_trace_kprobe(struct trace_event_call *event_call);
extern struct trace_event_call *
create_local_trace_uprobe(char *name, unsigned long offs,
unsigned long ref_ctr_offset, bool is_return);
extern void destroy_local_trace_uprobe(struct trace_event_call *event_call);
#endif
extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
size_t offset, struct trace_probe *tp);
#undef ERRORS
#define ERRORS \
C(FILE_NOT_FOUND, "Failed to find the given file"), \
C(NO_REGULAR_FILE, "Not a regular file"), \
C(BAD_REFCNT, "Invalid reference counter offset"), \
C(REFCNT_OPEN_BRACE, "Reference counter brace is not closed"), \
C(BAD_REFCNT_SUFFIX, "Reference counter has wrong suffix"), \
C(BAD_UPROBE_OFFS, "Invalid uprobe offset"), \
C(MAXACT_NO_KPROBE, "Maxactive is not for kprobe"), \
C(BAD_MAXACT, "Invalid maxactive number"), \
C(MAXACT_TOO_BIG, "Maxactive is too big"), \
C(BAD_PROBE_ADDR, "Invalid probed address or symbol"), \
C(BAD_RETPROBE, "Retprobe address must be an function entry"), \
C(BAD_ADDR_SUFFIX, "Invalid probed address suffix"), \
C(NO_GROUP_NAME, "Group name is not specified"), \
C(GROUP_TOO_LONG, "Group name is too long"), \
C(BAD_GROUP_NAME, "Group name must follow the same rules as C identifiers"), \
C(NO_EVENT_NAME, "Event name is not specified"), \
C(EVENT_TOO_LONG, "Event name is too long"), \
C(BAD_EVENT_NAME, "Event name must follow the same rules as C identifiers"), \
C(EVENT_EXIST, "Given group/event name is already used by another event"), \
C(RETVAL_ON_PROBE, "$retval is not available on probe"), \
C(BAD_STACK_NUM, "Invalid stack number"), \
C(BAD_ARG_NUM, "Invalid argument number"), \
C(BAD_VAR, "Invalid $-valiable specified"), \
C(BAD_REG_NAME, "Invalid register name"), \
C(BAD_MEM_ADDR, "Invalid memory address"), \
C(BAD_IMM, "Invalid immediate value"), \
C(IMMSTR_NO_CLOSE, "String is not closed with '\"'"), \
C(FILE_ON_KPROBE, "File offset is not available with kprobe"), \
C(BAD_FILE_OFFS, "Invalid file offset value"), \
C(SYM_ON_UPROBE, "Symbol is not available with uprobe"), \
C(TOO_MANY_OPS, "Dereference is too much nested"), \
C(DEREF_NEED_BRACE, "Dereference needs a brace"), \
C(BAD_DEREF_OFFS, "Invalid dereference offset"), \
C(DEREF_OPEN_BRACE, "Dereference brace is not closed"), \
C(COMM_CANT_DEREF, "$comm can not be dereferenced"), \
C(BAD_FETCH_ARG, "Invalid fetch argument"), \
C(ARRAY_NO_CLOSE, "Array is not closed"), \
C(BAD_ARRAY_SUFFIX, "Array has wrong suffix"), \
C(BAD_ARRAY_NUM, "Invalid array size"), \
C(ARRAY_TOO_BIG, "Array number is too big"), \
C(BAD_TYPE, "Unknown type is specified"), \
C(BAD_STRING, "String accepts only memory argument"), \
C(BAD_BITFIELD, "Invalid bitfield"), \
C(ARG_NAME_TOO_LONG, "Argument name is too long"), \
C(NO_ARG_NAME, "Argument name is not specified"), \
C(BAD_ARG_NAME, "Argument name must follow the same rules as C identifiers"), \
C(USED_ARG_NAME, "This argument name is already used"), \
C(ARG_TOO_LONG, "Argument expression is too long"), \
C(NO_ARG_BODY, "No argument expression"), \
C(BAD_INSN_BNDRY, "Probe point is not an instruction boundary"),\
C(FAIL_REG_PROBE, "Failed to register probe event"),\
C(DIFF_PROBE_TYPE, "Probe type is different from existing probe"),\
C(DIFF_ARG_TYPE, "Argument type or name is different from existing probe"),\
C(SAME_PROBE, "There is already the exact same probe event"),
#undef C
#define C(a, b) TP_ERR_##a
/* Define TP_ERR_ */
enum { ERRORS };
/* Error text is defined in trace_probe.c */
struct trace_probe_log {
const char *subsystem;
const char **argv;
int argc;
int index;
};
void trace_probe_log_init(const char *subsystem, int argc, const char **argv);
void trace_probe_log_set_index(int index);
void trace_probe_log_clear(void);
void __trace_probe_log_err(int offset, int err);
#define trace_probe_log_err(offs, err) \
__trace_probe_log_err(offs, TP_ERR_##err)
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