linux/tools/perf/util/trace-event.h
Frederic Weisbecker 4653881802 perf sched: Fix bad event alignment
perf sched raises the following error when it meets a sched
switch event:

perf: builtin-sched.c:286: register_pid: Assertion `!(pid >= 65536)' failed.
Abandon

Currently in x86-64, the sched switch events have a hole in the
middle of the structure:

	u16 common_type;
	u8 common_flags;
	u8 common_preempt_count;
	u32 common_pid;
	u32 common_tgid;

	char prev_comm[16];
	u32 prev_pid;
	u32 prev_prio;
			<--- there
	u64 prev_state;
	char next_comm[16];
	u32 next_pid;
	u32 next_prio;

Gcc inserts a 4 bytes hole there for prev_state to be u64
aligned. And the events are exported to userspace with this
hole.

But in userspace, from perf sched, we fetch it using a
structure that has a new field in the beginning: u32 size. This
is because our trace is exported with its size as a field. But
now that we have this new field, the hole in the middle
disappears because it makes prev_state becoming well aligned.

And since we are using a pointer to the raw trace using this
struct, instead of reading prev_state, we are reading the hole.

We could fix it by keeping the size seperate from the struct
but actually there a lot of other potential problems: some
fields may be saved as long in a 64 bits system and later read
as long in a 32 bits system. Also this direct cast doesn't care
about the endianness differences between the host traced
machine and the machine in which we do the post processing.

So instead of using such dangerous direct casts, fetch the
values using the trace parsing API that already takes care of
all these problems.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-13 10:22:41 +02:00

245 lines
4.7 KiB
C

#ifndef _TRACE_EVENTS_H
#define _TRACE_EVENTS_H
#include "parse-events.h"
#define __unused __attribute__((unused))
#ifndef PAGE_MASK
#define PAGE_MASK (page_size - 1)
#endif
enum {
RINGBUF_TYPE_PADDING = 29,
RINGBUF_TYPE_TIME_EXTEND = 30,
RINGBUF_TYPE_TIME_STAMP = 31,
};
#ifndef TS_SHIFT
#define TS_SHIFT 27
#endif
#define NSECS_PER_SEC 1000000000ULL
#define NSECS_PER_USEC 1000ULL
enum format_flags {
FIELD_IS_ARRAY = 1,
FIELD_IS_POINTER = 2,
};
struct format_field {
struct format_field *next;
char *type;
char *name;
int offset;
int size;
unsigned long flags;
};
struct format {
int nr_common;
int nr_fields;
struct format_field *common_fields;
struct format_field *fields;
};
struct print_arg_atom {
char *atom;
};
struct print_arg_string {
char *string;
int offset;
};
struct print_arg_field {
char *name;
struct format_field *field;
};
struct print_flag_sym {
struct print_flag_sym *next;
char *value;
char *str;
};
struct print_arg_typecast {
char *type;
struct print_arg *item;
};
struct print_arg_flags {
struct print_arg *field;
char *delim;
struct print_flag_sym *flags;
};
struct print_arg_symbol {
struct print_arg *field;
struct print_flag_sym *symbols;
};
struct print_arg;
struct print_arg_op {
char *op;
int prio;
struct print_arg *left;
struct print_arg *right;
};
struct print_arg_func {
char *name;
struct print_arg *args;
};
enum print_arg_type {
PRINT_NULL,
PRINT_ATOM,
PRINT_FIELD,
PRINT_FLAGS,
PRINT_SYMBOL,
PRINT_TYPE,
PRINT_STRING,
PRINT_OP,
};
struct print_arg {
struct print_arg *next;
enum print_arg_type type;
union {
struct print_arg_atom atom;
struct print_arg_field field;
struct print_arg_typecast typecast;
struct print_arg_flags flags;
struct print_arg_symbol symbol;
struct print_arg_func func;
struct print_arg_string string;
struct print_arg_op op;
};
};
struct print_fmt {
char *format;
struct print_arg *args;
};
struct event {
struct event *next;
char *name;
int id;
int flags;
struct format format;
struct print_fmt print_fmt;
};
enum {
EVENT_FL_ISFTRACE = 1,
EVENT_FL_ISPRINT = 2,
EVENT_FL_ISBPRINT = 4,
EVENT_FL_ISFUNC = 8,
EVENT_FL_ISFUNCENT = 16,
EVENT_FL_ISFUNCRET = 32,
};
struct record {
unsigned long long ts;
int size;
void *data;
};
struct record *trace_peek_data(int cpu);
struct record *trace_read_data(int cpu);
void parse_set_info(int nr_cpus, int long_sz);
void trace_report(void);
void *malloc_or_die(unsigned int size);
void parse_cmdlines(char *file, int size);
void parse_proc_kallsyms(char *file, unsigned int size);
void parse_ftrace_printk(char *file, unsigned int size);
void print_funcs(void);
void print_printk(void);
int parse_ftrace_file(char *buf, unsigned long size);
int parse_event_file(char *buf, unsigned long size, char *system);
void print_event(int cpu, void *data, int size, unsigned long long nsecs,
char *comm);
extern int file_bigendian;
extern int host_bigendian;
int bigendian(void);
static inline unsigned short __data2host2(unsigned short data)
{
unsigned short swap;
if (host_bigendian == file_bigendian)
return data;
swap = ((data & 0xffULL) << 8) |
((data & (0xffULL << 8)) >> 8);
return swap;
}
static inline unsigned int __data2host4(unsigned int data)
{
unsigned int swap;
if (host_bigendian == file_bigendian)
return data;
swap = ((data & 0xffULL) << 24) |
((data & (0xffULL << 8)) << 8) |
((data & (0xffULL << 16)) >> 8) |
((data & (0xffULL << 24)) >> 24);
return swap;
}
static inline unsigned long long __data2host8(unsigned long long data)
{
unsigned long long swap;
if (host_bigendian == file_bigendian)
return data;
swap = ((data & 0xffULL) << 56) |
((data & (0xffULL << 8)) << 40) |
((data & (0xffULL << 16)) << 24) |
((data & (0xffULL << 24)) << 8) |
((data & (0xffULL << 32)) >> 8) |
((data & (0xffULL << 40)) >> 24) |
((data & (0xffULL << 48)) >> 40) |
((data & (0xffULL << 56)) >> 56);
return swap;
}
#define data2host2(ptr) __data2host2(*(unsigned short *)ptr)
#define data2host4(ptr) __data2host4(*(unsigned int *)ptr)
#define data2host8(ptr) __data2host8(*(unsigned long long *)ptr)
extern int header_page_ts_offset;
extern int header_page_ts_size;
extern int header_page_size_offset;
extern int header_page_size_size;
extern int header_page_data_offset;
extern int header_page_data_size;
int parse_header_page(char *buf, unsigned long size);
int trace_parse_common_type(void *data);
struct event *trace_find_event(int id);
unsigned long long
raw_field_value(struct event *event, const char *name, void *data);
void *raw_field_ptr(struct event *event, const char *name, void *data);
void read_tracing_data(struct perf_counter_attr *pattrs, int nb_counters);
#endif /* _TRACE_EVENTS_H */