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remarkable-linux/include/linux/ftrace.h
Frederic Weisbecker 287b6e68ca tracing/function-return-tracer: set a more human readable output 
Impact: feature

This patch sets a C-like output for the function graph tracing.
For this aim, we now call two handler for each function: one on the entry
and one other on return. This way we can draw a well-ordered call stack.

The pid of the previous trace is loosely stored to be compared against
the one of the current trace to see if there were a context switch.

Without this little feature, the call tree would seem broken at
some locations.
We could use the sched_tracer to capture these sched_events but this
way of processing is much more simpler.

2 spaces have been chosen for indentation to fit the screen while deep
calls. The time of execution in nanosecs is printed just after closed
braces, it seems more easy this way to find the corresponding function.
If the time was printed as a first column, it would be not so easy to
find the corresponding function if it is called on a deep depth.

I plan to output the return value but on 32 bits CPU, the return value
can be 32 or 64, and its difficult to guess on which case we are.
I don't know what would be the better solution on X86-32: only print
eax (low-part) or even edx (high-part).

Actually it's thee same problem when a function return a 8 bits value, the
high part of eax could contain junk values...

Here is an example of trace:

sys_read() {
  fget_light() {
  } 526
  vfs_read() {
    rw_verify_area() {
      security_file_permission() {
        cap_file_permission() {
        } 519
      } 1564
    } 2640
    do_sync_read() {
      pipe_read() {
        __might_sleep() {
        } 511
        pipe_wait() {
          prepare_to_wait() {
          } 760
          deactivate_task() {
            dequeue_task() {
              dequeue_task_fair() {
                dequeue_entity() {
                  update_curr() {
                    update_min_vruntime() {
                    } 504
                  } 1587
                  clear_buddies() {
                  } 512
                  add_cfs_task_weight() {
                  } 519
                  update_min_vruntime() {
                  } 511
                } 5602
                dequeue_entity() {
                  update_curr() {
                    update_min_vruntime() {
                    } 496
                  } 1631
                  clear_buddies() {
                  } 496
                  update_min_vruntime() {
                  } 527
                } 4580
                hrtick_update() {
                  hrtick_start_fair() {
                  } 488
                } 1489
              } 13700
            } 14949
          } 16016
          msecs_to_jiffies() {
          } 496
          put_prev_task_fair() {
          } 504
          pick_next_task_fair() {
          } 489
          pick_next_task_rt() {
          } 496
          pick_next_task_fair() {
          } 489
          pick_next_task_idle() {
          } 489

------------8<---------- thread 4 ------------8<----------

finish_task_switch() {
} 1203
do_softirq() {
  __do_softirq() {
    __local_bh_disable() {
    } 669
    rcu_process_callbacks() {
      __rcu_process_callbacks() {
        cpu_quiet() {
          rcu_start_batch() {
          } 503
        } 1647
      } 3128
      __rcu_process_callbacks() {
      } 542
    } 5362
    _local_bh_enable() {
    } 587
  } 8880
} 9986
kthread_should_stop() {
} 669
deactivate_task() {
  dequeue_task() {
    dequeue_task_fair() {
      dequeue_entity() {
        update_curr() {
          calc_delta_mine() {
          } 511
          update_min_vruntime() {
          } 511
        } 2813

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-26 01:59:45 +01:00

359 lines
11 KiB
C
Raw Blame History

#ifndef _LINUX_FTRACE_H
#define _LINUX_FTRACE_H
#include <linux/linkage.h>
#include <linux/fs.h>
#include <linux/ktime.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/kallsyms.h>
#ifdef CONFIG_FUNCTION_TRACER
extern int ftrace_enabled;
extern int
ftrace_enable_sysctl(struct ctl_table *table, int write,
struct file *filp, void __user *buffer, size_t *lenp,
loff_t *ppos);
typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip);
struct ftrace_ops {
ftrace_func_t func;
struct ftrace_ops *next;
};
extern int function_trace_stop;
/*
* Type of the current tracing.
*/
enum ftrace_tracing_type_t {
FTRACE_TYPE_ENTER = 0, /* Hook the call of the function */
FTRACE_TYPE_RETURN, /* Hook the return of the function */
};
/* Current tracing type, default is FTRACE_TYPE_ENTER */
extern enum ftrace_tracing_type_t ftrace_tracing_type;
/**
* ftrace_stop - stop function tracer.
*
* A quick way to stop the function tracer. Note this an on off switch,
* it is not something that is recursive like preempt_disable.
* This does not disable the calling of mcount, it only stops the
* calling of functions from mcount.
*/
static inline void ftrace_stop(void)
{
function_trace_stop = 1;
}
/**
* ftrace_start - start the function tracer.
*
* This function is the inverse of ftrace_stop. This does not enable
* the function tracing if the function tracer is disabled. This only
* sets the function tracer flag to continue calling the functions
* from mcount.
*/
static inline void ftrace_start(void)
{
function_trace_stop = 0;
}
/*
* The ftrace_ops must be a static and should also
* be read_mostly. These functions do modify read_mostly variables
* so use them sparely. Never free an ftrace_op or modify the
* next pointer after it has been registered. Even after unregistering
* it, the next pointer may still be used internally.
*/
int register_ftrace_function(struct ftrace_ops *ops);
int unregister_ftrace_function(struct ftrace_ops *ops);
void clear_ftrace_function(void);
extern void ftrace_stub(unsigned long a0, unsigned long a1);
#else /* !CONFIG_FUNCTION_TRACER */
# define register_ftrace_function(ops) do { } while (0)
# define unregister_ftrace_function(ops) do { } while (0)
# define clear_ftrace_function(ops) do { } while (0)
static inline void ftrace_kill(void) { }
static inline void ftrace_stop(void) { }
static inline void ftrace_start(void) { }
#endif /* CONFIG_FUNCTION_TRACER */
#ifdef CONFIG_DYNAMIC_FTRACE
/* asm/ftrace.h must be defined for archs supporting dynamic ftrace */
#include <asm/ftrace.h>
enum {
FTRACE_FL_FREE = (1 << 0),
FTRACE_FL_FAILED = (1 << 1),
FTRACE_FL_FILTER = (1 << 2),
FTRACE_FL_ENABLED = (1 << 3),
FTRACE_FL_NOTRACE = (1 << 4),
FTRACE_FL_CONVERTED = (1 << 5),
FTRACE_FL_FROZEN = (1 << 6),
};
struct dyn_ftrace {
struct list_head list;
unsigned long ip; /* address of mcount call-site */
unsigned long flags;
struct dyn_arch_ftrace arch;
};
int ftrace_force_update(void);
void ftrace_set_filter(unsigned char *buf, int len, int reset);
/* defined in arch */
extern int ftrace_ip_converted(unsigned long ip);
extern int ftrace_dyn_arch_init(void *data);
extern int ftrace_update_ftrace_func(ftrace_func_t func);
extern void ftrace_caller(void);
extern void ftrace_call(void);
extern void mcount_call(void);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
extern void ftrace_graph_caller(void);
#endif
/**
* ftrace_make_nop - convert code into top
* @mod: module structure if called by module load initialization
* @rec: the mcount call site record
* @addr: the address that the call site should be calling
*
* This is a very sensitive operation and great care needs
* to be taken by the arch. The operation should carefully
* read the location, check to see if what is read is indeed
* what we expect it to be, and then on success of the compare,
* it should write to the location.
*
* The code segment at @rec->ip should be a caller to @addr
*
* Return must be:
* 0 on success
* -EFAULT on error reading the location
* -EINVAL on a failed compare of the contents
* -EPERM on error writing to the location
* Any other value will be considered a failure.
*/
extern int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr);
/**
* ftrace_make_call - convert a nop call site into a call to addr
* @rec: the mcount call site record
* @addr: the address that the call site should call
*
* This is a very sensitive operation and great care needs
* to be taken by the arch. The operation should carefully
* read the location, check to see if what is read is indeed
* what we expect it to be, and then on success of the compare,
* it should write to the location.
*
* The code segment at @rec->ip should be a nop
*
* Return must be:
* 0 on success
* -EFAULT on error reading the location
* -EINVAL on a failed compare of the contents
* -EPERM on error writing to the location
* Any other value will be considered a failure.
*/
extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr);
/* May be defined in arch */
extern int ftrace_arch_read_dyn_info(char *buf, int size);
extern int skip_trace(unsigned long ip);
extern void ftrace_release(void *start, unsigned long size);
extern void ftrace_disable_daemon(void);
extern void ftrace_enable_daemon(void);
#else
# define skip_trace(ip) ({ 0; })
# define ftrace_force_update() ({ 0; })
# define ftrace_set_filter(buf, len, reset) do { } while (0)
# define ftrace_disable_daemon() do { } while (0)
# define ftrace_enable_daemon() do { } while (0)
static inline void ftrace_release(void *start, unsigned long size) { }
#endif /* CONFIG_DYNAMIC_FTRACE */
/* totally disable ftrace - can not re-enable after this */
void ftrace_kill(void);
static inline void tracer_disable(void)
{
#ifdef CONFIG_FUNCTION_TRACER
ftrace_enabled = 0;
#endif
}
/*
* Ftrace disable/restore without lock. Some synchronization mechanism
* must be used to prevent ftrace_enabled to be changed between
* disable/restore.
*/
static inline int __ftrace_enabled_save(void)
{
#ifdef CONFIG_FUNCTION_TRACER
int saved_ftrace_enabled = ftrace_enabled;
ftrace_enabled = 0;
return saved_ftrace_enabled;
#else
return 0;
#endif
}
static inline void __ftrace_enabled_restore(int enabled)
{
#ifdef CONFIG_FUNCTION_TRACER
ftrace_enabled = enabled;
#endif
}
#ifdef CONFIG_FRAME_POINTER
/* TODO: need to fix this for ARM */
# define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
# define CALLER_ADDR1 ((unsigned long)__builtin_return_address(1))
# define CALLER_ADDR2 ((unsigned long)__builtin_return_address(2))
# define CALLER_ADDR3 ((unsigned long)__builtin_return_address(3))
# define CALLER_ADDR4 ((unsigned long)__builtin_return_address(4))
# define CALLER_ADDR5 ((unsigned long)__builtin_return_address(5))
# define CALLER_ADDR6 ((unsigned long)__builtin_return_address(6))
#else
# define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
# define CALLER_ADDR1 0UL
# define CALLER_ADDR2 0UL
# define CALLER_ADDR3 0UL
# define CALLER_ADDR4 0UL
# define CALLER_ADDR5 0UL
# define CALLER_ADDR6 0UL
#endif
#ifdef CONFIG_IRQSOFF_TRACER
extern void time_hardirqs_on(unsigned long a0, unsigned long a1);
extern void time_hardirqs_off(unsigned long a0, unsigned long a1);
#else
# define time_hardirqs_on(a0, a1) do { } while (0)
# define time_hardirqs_off(a0, a1) do { } while (0)
#endif
#ifdef CONFIG_PREEMPT_TRACER
extern void trace_preempt_on(unsigned long a0, unsigned long a1);
extern void trace_preempt_off(unsigned long a0, unsigned long a1);
#else
# define trace_preempt_on(a0, a1) do { } while (0)
# define trace_preempt_off(a0, a1) do { } while (0)
#endif
#ifdef CONFIG_TRACING
extern int ftrace_dump_on_oops;
extern void tracing_start(void);
extern void tracing_stop(void);
extern void ftrace_off_permanent(void);
extern void
ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3);
/**
* ftrace_printk - printf formatting in the ftrace buffer
* @fmt: the printf format for printing
*
* Note: __ftrace_printk is an internal function for ftrace_printk and
* the @ip is passed in via the ftrace_printk macro.
*
* This function allows a kernel developer to debug fast path sections
* that printk is not appropriate for. By scattering in various
* printk like tracing in the code, a developer can quickly see
* where problems are occurring.
*
* This is intended as a debugging tool for the developer only.
* Please refrain from leaving ftrace_printks scattered around in
* your code.
*/
# define ftrace_printk(fmt...) __ftrace_printk(_THIS_IP_, fmt)
extern int
__ftrace_printk(unsigned long ip, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
extern void ftrace_dump(void);
#else
static inline void
ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
static inline int
ftrace_printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 0)));
static inline void tracing_start(void) { }
static inline void tracing_stop(void) { }
static inline void ftrace_off_permanent(void) { }
static inline int
ftrace_printk(const char *fmt, ...)
{
return 0;
}
static inline void ftrace_dump(void) { }
#endif
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
extern void ftrace_init(void);
extern void ftrace_init_module(struct module *mod,
unsigned long *start, unsigned long *end);
#else
static inline void ftrace_init(void) { }
static inline void
ftrace_init_module(struct module *mod,
unsigned long *start, unsigned long *end) { }
#endif
/*
* Structure that defines an entry function trace.
*/
struct ftrace_graph_ent {
unsigned long func; /* Current function */
int depth;
};
/*
* Structure that defines a return function trace.
*/
struct ftrace_graph_ret {
unsigned long func; /* Current function */
unsigned long long calltime;
unsigned long long rettime;
/* Number of functions that overran the depth limit for current task */
unsigned long overrun;
int depth;
};
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
#define FTRACE_RETFUNC_DEPTH 50
#define FTRACE_RETSTACK_ALLOC_SIZE 32
/* Type of the callback handlers for tracing function graph*/
typedef void (*trace_func_graph_ret_t)(struct ftrace_graph_ret *); /* return */
typedef void (*trace_func_graph_ent_t)(struct ftrace_graph_ent *); /* entry */
extern int register_ftrace_graph(trace_func_graph_ret_t retfunc,
trace_func_graph_ent_t entryfunc);
/* The current handlers in use */
extern trace_func_graph_ret_t ftrace_graph_return;
extern trace_func_graph_ent_t ftrace_graph_entry;
extern void unregister_ftrace_graph(void);
extern void ftrace_graph_init_task(struct task_struct *t);
extern void ftrace_graph_exit_task(struct task_struct *t);
#else
static inline void ftrace_graph_init_task(struct task_struct *t) { }
static inline void ftrace_graph_exit_task(struct task_struct *t) { }
#endif
#endif /* _LINUX_FTRACE_H */
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