[PATCH 2/11] oprofile: arch-independent code for stack trace sampling

From: Greg Banks (gnb_at_melbourne.sgi.com)
Date: 11/09/04

  • Next message: Zachariah : "syria"
    To: Andrew Morton <akpm@osdl.org>
    Date:	Tue, 09 Nov 2004 21:37:48 +1100
    
    
    

    -- 
    Greg Banks, R&D Software Engineer, SGI Australian Software Group.
    I don't speak for SGI.
    
    

    oprofile arch-independent updates, including some internal
    API changes and support for stack trace sampling.

    Signed-off-by: John Levon <levon@movementarian.org>
    Signed-off-by: Greg Banks <gnb@melbourne.sgi.com>

    ---
     drivers/oprofile/buffer_sync.c    |   57 ++++++++++++---
     drivers/oprofile/cpu_buffer.c     |  141 ++++++++++++++++++++++++++++++--------
     drivers/oprofile/cpu_buffer.h     |    6 +
     drivers/oprofile/event_buffer.h   |    2 
     drivers/oprofile/oprof.c          |   74 +++++++++++--------
     drivers/oprofile/oprof.h          |    5 +
     drivers/oprofile/oprofile_files.c |   42 +++++++++--
     drivers/oprofile/oprofile_stats.c |    4 +
     drivers/oprofile/oprofile_stats.h |    1 
     drivers/oprofile/timer_int.c      |   19 +----
     include/linux/oprofile.h          |   20 ++++-
     11 files changed, 279 insertions(+), 92 deletions(-)
    Index: linux/drivers/oprofile/oprofile_files.c
    ===================================================================
    --- linux.orig/drivers/oprofile/oprofile_files.c	2004-10-19 07:54:08.%N +1000
    +++ linux/drivers/oprofile/oprofile_files.c	2004-11-07 18:00:02.%N +1100
    @@ -18,6 +18,37 @@ unsigned long fs_buffer_size = 131072;
     unsigned long fs_cpu_buffer_size = 8192;
     unsigned long fs_buffer_watershed = 32768; /* FIXME: tune */
     
    +static ssize_t depth_read(struct file * file, char * buf, size_t count, loff_t * offset)
    +{
    +	return oprofilefs_ulong_to_user(backtrace_depth, buf, count, offset);
    +}
    +
    + 
    +static ssize_t depth_write(struct file * file, char const * buf, size_t count, loff_t * offset)
    +{
    +	unsigned long val;
    +	int retval;
    +
    +	if (*offset)
    +		return -EINVAL;
    +
    +	retval = oprofilefs_ulong_from_user(&val, buf, count);
    +	if (retval)
    +		return retval;
    +  
    +	retval = oprofile_set_backtrace(val);
    +
    +	if (retval)
    +		return retval;
    +	return count;
    +}
    +
    +
    +static struct file_operations depth_fops = {
    +	.read		= depth_read,
    +	.write		= depth_write
    +};
    +
      
     static ssize_t pointer_size_read(struct file * file, char __user * buf, size_t count, loff_t * offset)
     {
    @@ -32,7 +63,7 @@ static struct file_operations pointer_si
     
     static ssize_t cpu_type_read(struct file * file, char __user * buf, size_t count, loff_t * offset)
     {
    -	return oprofilefs_str_to_user(oprofile_ops->cpu_type, buf, count, offset);
    +	return oprofilefs_str_to_user(oprofile_ops.cpu_type, buf, count, offset);
     }
      
      
    @@ -47,7 +78,7 @@ static ssize_t enable_read(struct file *
     }
     
     
    -static ssize_t enable_write(struct file *file, char const __user * buf, size_t count, loff_t * offset)
    +static ssize_t enable_write(struct file * file, char const __user * buf, size_t count, loff_t * offset)
     {
     	unsigned long val;
     	int retval;
    @@ -76,7 +107,7 @@ static struct file_operations enable_fop
     };
     
     
    -static ssize_t dump_write(struct file *file, char const __user * buf, size_t count, loff_t * offset)
    +static ssize_t dump_write(struct file * file, char const __user * buf, size_t count, loff_t * offset)
     {
     	wake_up_buffer_waiter();
     	return count;
    @@ -96,8 +127,9 @@ void oprofile_create_files(struct super_
     	oprofilefs_create_ulong(sb, root, "buffer_watershed", &fs_buffer_watershed);
     	oprofilefs_create_ulong(sb, root, "cpu_buffer_size", &fs_cpu_buffer_size);
     	oprofilefs_create_file(sb, root, "cpu_type", &cpu_type_fops); 
    +	oprofilefs_create_file(sb, root, "backtrace_depth", &depth_fops);
     	oprofilefs_create_file(sb, root, "pointer_size", &pointer_size_fops);
     	oprofile_create_stats_files(sb, root);
    -	if (oprofile_ops->create_files)
    -		oprofile_ops->create_files(sb, root);
    +	if (oprofile_ops.create_files)
    +		oprofile_ops.create_files(sb, root);
     }
    Index: linux/drivers/oprofile/oprofile_stats.h
    ===================================================================
    --- linux.orig/drivers/oprofile/oprofile_stats.h	2004-10-19 07:55:36.%N +1000
    +++ linux/drivers/oprofile/oprofile_stats.h	2004-11-07 18:00:02.%N +1100
    @@ -15,6 +15,7 @@
     struct oprofile_stat_struct {
     	atomic_t sample_lost_no_mm;
     	atomic_t sample_lost_no_mapping;
    +	atomic_t bt_lost_no_mapping;
     	atomic_t event_lost_overflow;
     };
     
    Index: linux/include/linux/oprofile.h
    ===================================================================
    --- linux.orig/include/linux/oprofile.h	2004-10-19 07:54:37.%N +1000
    +++ linux/include/linux/oprofile.h	2004-11-07 18:00:02.%N +1100
    @@ -20,6 +20,7 @@
     struct super_block;
     struct dentry;
     struct file_operations;
    +struct pt_regs;
      
     /* Operations structure to be filled in */
     struct oprofile_operations {
    @@ -34,6 +35,8 @@ struct oprofile_operations {
     	int (*start)(void);
     	/* Stop delivering interrupts. */
     	void (*stop)(void);
    +	/* Initiate a stack backtrace. Optional. */
    +	void (*backtrace)(struct pt_regs * const regs, unsigned int depth);
     	/* CPU identification string. */
     	char * cpu_type;
     };
    @@ -41,11 +44,11 @@ struct oprofile_operations {
     /**
      * One-time initialisation. *ops must be set to a filled-in
      * operations structure. This is called even in timer interrupt
    - * mode.
    + * mode so an arch can set a backtrace callback.
      *
    - * Return 0 on success.
    + * If an error occurs, the fields should be left untouched.
      */
    -int oprofile_arch_init(struct oprofile_operations ** ops);
    +void oprofile_arch_init(struct oprofile_operations * ops);
      
     /**
      * One-time exit/cleanup for the arch.
    @@ -56,8 +59,15 @@ void oprofile_arch_exit(void);
      * Add a sample. This may be called from any context. Pass
      * smp_processor_id() as cpu.
      */
    -extern void oprofile_add_sample(unsigned long eip, unsigned int is_kernel, 
    -	unsigned long event, int cpu);
    +void oprofile_add_sample(struct pt_regs * const regs, unsigned long event);
    +
    +/* Use this instead when the PC value is not from the regs. Doesn't
    + * backtrace. */
    +void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event);
    +
    +/* add a backtrace entry, to be called from the ->backtrace callback */
    +void oprofile_add_trace(unsigned long eip);
    +
     
     /**
      * Create a file of the given name as a child of the given root, with
    Index: linux/drivers/oprofile/cpu_buffer.c
    ===================================================================
    --- linux.orig/drivers/oprofile/cpu_buffer.c	2004-10-19 07:53:06.%N +1000
    +++ linux/drivers/oprofile/cpu_buffer.c	2004-11-07 18:00:02.%N +1100
    @@ -18,9 +18,11 @@
      */
     
     #include <linux/sched.h>
    +#include <linux/oprofile.h>
     #include <linux/vmalloc.h>
     #include <linux/errno.h>
      
    +#include "event_buffer.h" 
     #include "cpu_buffer.h"
     #include "buffer_sync.h"
     #include "oprof.h"
    @@ -58,6 +60,7 @@ int alloc_cpu_buffers(void)
      
     		b->last_task = NULL;
     		b->last_is_kernel = -1;
    +		b->tracing = 0;
     		b->buffer_size = buffer_size;
     		b->tail_pos = 0;
     		b->head_pos = 0;
    @@ -114,6 +117,18 @@ void end_cpu_work(void)
     }
     
     
    +/* Resets the cpu buffer to a sane state. */
    +void cpu_buffer_reset(struct oprofile_cpu_buffer * cpu_buf)
    +{
    +	/* reset these to invalid values; the next sample
    +	 * collected will populate the buffer with proper
    +	 * values to initialize the buffer
    +	 */
    +	cpu_buf->last_is_kernel = -1;
    +	cpu_buf->last_task = NULL;
    +}
    +
    +
     /* compute number of available slots in cpu_buffer queue */
     static unsigned long nr_available_slots(struct oprofile_cpu_buffer const * b)
     {
    @@ -135,74 +150,148 @@ static void increment_head(struct oprofi
     	 * increment is visible */
     	wmb();
     
    -	if (new_head < (b->buffer_size))
    +	if (new_head < b->buffer_size)
     		b->head_pos = new_head;
     	else
     		b->head_pos = 0;
     }
     
     
    +
    +
    +inline static void
    +add_sample(struct oprofile_cpu_buffer * cpu_buf,
    +           unsigned long pc, unsigned long event)
    +{
    +	struct op_sample * entry = &cpu_buf->buffer[cpu_buf->head_pos];
    +	entry->eip = pc;
    +	entry->event = event;
    +	increment_head(cpu_buf);
    +}
    +
    +
    +inline static void
    +add_code(struct oprofile_cpu_buffer * buffer, unsigned long value)
    +{
    +	add_sample(buffer, ESCAPE_CODE, value);
    +}
    +
    +
     /* This must be safe from any context. It's safe writing here
      * because of the head/tail separation of the writer and reader
      * of the CPU buffer.
      *
      * is_kernel is needed because on some architectures you cannot
      * tell if you are in kernel or user space simply by looking at
    - * eip. We tag this in the buffer by generating kernel enter/exit
    + * pc. We tag this in the buffer by generating kernel enter/exit
      * events whenever is_kernel changes
      */
    -void oprofile_add_sample(unsigned long eip, unsigned int is_kernel, 
    -	unsigned long event, int cpu)
    +static int log_sample(struct oprofile_cpu_buffer * cpu_buf, unsigned long pc,
    +		      int is_kernel, unsigned long event)
     {
    -	struct oprofile_cpu_buffer * cpu_buf = &cpu_buffer[cpu];
     	struct task_struct * task;
     
    -	is_kernel = !!is_kernel;
    -
     	cpu_buf->sample_received++;
    - 
     
     	if (nr_available_slots(cpu_buf) < 3) {
     		cpu_buf->sample_lost_overflow++;
    -		return;
    +		return 0;
     	}
     
    +	is_kernel = !!is_kernel;
    +
     	task = current;
     
     	/* notice a switch from user->kernel or vice versa */
     	if (cpu_buf->last_is_kernel != is_kernel) {
     		cpu_buf->last_is_kernel = is_kernel;
    -		cpu_buf->buffer[cpu_buf->head_pos].eip = ~0UL;
    -		cpu_buf->buffer[cpu_buf->head_pos].event = is_kernel;
    -		increment_head(cpu_buf);
    +		add_code(cpu_buf, is_kernel);
     	}
     
     	/* notice a task switch */
     	if (cpu_buf->last_task != task) {
     		cpu_buf->last_task = task;
    -		cpu_buf->buffer[cpu_buf->head_pos].eip = ~0UL;
    -		cpu_buf->buffer[cpu_buf->head_pos].event = (unsigned long)task;
    -		increment_head(cpu_buf);
    +		add_code(cpu_buf, (unsigned long)task);
     	}
      
    -	cpu_buf->buffer[cpu_buf->head_pos].eip = eip;
    -	cpu_buf->buffer[cpu_buf->head_pos].event = event;
    -	increment_head(cpu_buf);
    +	add_sample(cpu_buf, pc, event);
    +	return 1;
     }
     
    +static int oprofile_begin_trace(struct oprofile_cpu_buffer * cpu_buf)
    +{
    +	if (nr_available_slots(cpu_buf) < 4) {
    +		cpu_buf->sample_lost_overflow++;
    +		return 0;
    +	}
     
    -/* Resets the cpu buffer to a sane state. */
    -void cpu_buffer_reset(struct oprofile_cpu_buffer * cpu_buf)
    +	add_code(cpu_buf, CPU_TRACE_BEGIN);
    +	cpu_buf->tracing = 1;
    +	return 1;
    +}
    +
    +
    +static void oprofile_end_trace(struct oprofile_cpu_buffer * cpu_buf)
     {
    -	/* reset these to invalid values; the next sample
    -	 * collected will populate the buffer with proper
    -	 * values to initialize the buffer
    -	 */
    -	cpu_buf->last_is_kernel = -1;
    -	cpu_buf->last_task = NULL;
    +	cpu_buf->tracing = 0;
    +}
    +
    +
    +void oprofile_add_sample(struct pt_regs * const regs, unsigned long event)
    +{
    +	struct oprofile_cpu_buffer * cpu_buf = &cpu_buffer[smp_processor_id()];
    +	unsigned long pc = instruction_pointer(regs);
    +	int is_kernel = !user_mode(regs);
    +
    +	if (!backtrace_depth) {
    +		log_sample(cpu_buf, pc, is_kernel, event);
    +		return;
    +	}
    +
    +	if (!oprofile_begin_trace(cpu_buf))
    +		return;
    +
    +	/* if log_sample() fail we can't backtrace since we lost the source
    +	 * of this event */
    +	if (log_sample(cpu_buf, pc, is_kernel, event))
    +		oprofile_ops.backtrace(regs, backtrace_depth);
    +	oprofile_end_trace(cpu_buf);
    +}
    +
    +
    +void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event)
    +{
    +	struct oprofile_cpu_buffer * cpu_buf = &cpu_buffer[smp_processor_id()];
    +	log_sample(cpu_buf, pc, is_kernel, event);
    +}
    +
    +
    +void oprofile_add_trace(unsigned long pc)
    +{
    +	struct oprofile_cpu_buffer * cpu_buf = &cpu_buffer[smp_processor_id()];
    +
    +	if (!cpu_buf->tracing)
    +		return;
    +
    +	if (nr_available_slots(cpu_buf) < 1) {
    +		cpu_buf->tracing = 0;
    +		cpu_buf->sample_lost_overflow++;
    +		return;
    +	}
    +
    +	/* broken frame can give an eip with the same value as an escape code,
    +	 * abort the trace if we get it */
    +	if (pc == ESCAPE_CODE) {
    +		cpu_buf->tracing = 0;
    +		cpu_buf->backtrace_aborted++;
    +		return;
    +	}
    +
    +	add_sample(cpu_buf, pc, 0);
     }
     
     
    +
     /*
      * This serves to avoid cpu buffer overflow, and makes sure
      * the task mortuary progresses
    Index: linux/drivers/oprofile/oprof.c
    ===================================================================
    --- linux.orig/drivers/oprofile/oprof.c	2004-10-19 07:53:44.%N +1000
    +++ linux/drivers/oprofile/oprof.c	2004-11-07 18:00:02.%N +1100
    @@ -20,8 +20,10 @@
     #include "buffer_sync.h"
     #include "oprofile_stats.h"
      
    -struct oprofile_operations * oprofile_ops;
    +struct oprofile_operations oprofile_ops;
    +
     unsigned long oprofile_started;
    +unsigned long backtrace_depth;
     static unsigned long is_setup;
     static DECLARE_MUTEX(start_sem);
     
    @@ -43,7 +45,7 @@ int oprofile_setup(void)
     	if ((err = alloc_event_buffer()))
     		goto out1;
      
    -	if (oprofile_ops->setup && (err = oprofile_ops->setup()))
    +	if (oprofile_ops.setup && (err = oprofile_ops.setup()))
     		goto out2;
      
     	/* Note even though this starts part of the
    @@ -59,8 +61,8 @@ int oprofile_setup(void)
     	return 0;
      
     out3:
    -	if (oprofile_ops->shutdown)
    -		oprofile_ops->shutdown();
    +	if (oprofile_ops.shutdown)
    +		oprofile_ops.shutdown();
     out2:
     	free_event_buffer();
     out1:
    @@ -88,7 +90,7 @@ int oprofile_start(void)
      
     	oprofile_reset_stats();
     
    -	if ((err = oprofile_ops->start()))
    +	if ((err = oprofile_ops.start()))
     		goto out;
     
     	oprofile_started = 1;
    @@ -104,7 +106,7 @@ void oprofile_stop(void)
     	down(&start_sem);
     	if (!oprofile_started)
     		goto out;
    -	oprofile_ops->stop();
    +	oprofile_ops.stop();
     	oprofile_started = 0;
     	/* wake up the daemon to read what remains */
     	wake_up_buffer_waiter();
    @@ -117,8 +119,8 @@ void oprofile_shutdown(void)
     {
     	down(&start_sem);
     	sync_stop();
    -	if (oprofile_ops->shutdown)
    -		oprofile_ops->shutdown(); 
    +	if (oprofile_ops.shutdown)
    +		oprofile_ops.shutdown(); 
     	is_setup = 0;
     	free_event_buffer();
     	free_cpu_buffers();
    @@ -126,38 +128,50 @@ void oprofile_shutdown(void)
     }
     
     
    -extern void timer_init(struct oprofile_operations ** ops);
    +int oprofile_set_backtrace(unsigned long val)
    +{
    +	int err = 0;
     
    +	down(&start_sem);
     
    -static int __init oprofile_init(void)
    -{
    -	/* Architecture must fill in the interrupt ops and the
    -	 * logical CPU type, or we can fall back to the timer
    -	 * interrupt profiler.
    -	 */
    -	int err = oprofile_arch_init(&oprofile_ops);
    +	if (oprofile_started) {
    +		err = -EBUSY;
    +		goto out;
    +	}
     
    -	if (err == -ENODEV || timer) {
    -		timer_init(&oprofile_ops);
    -		err = 0;
    -	} else if (err) {
    +	if (!oprofile_ops.backtrace) {
    +		err = -EINVAL;
     		goto out;
     	}
     
    -	if (!oprofile_ops->cpu_type) {
    -		printk(KERN_ERR "oprofile: cpu_type not set !\n");
    -		err = -EFAULT;
    +	backtrace_depth = val;
    +
    +out:
    +	up(&start_sem);
    +	return err;
    +}
    +
    +
    +extern void timer_init(struct oprofile_operations * ops);
    +
    +static int __init oprofile_init(void)
    +{
    +	int err = 0;
    +
    +	/* this is our fallback case */
    +	timer_init(&oprofile_ops);
    +
    +	if (timer) {
    +		printk(KERN_INFO "oprofile: using timer interrupt.\n");
     	} else {
    -		err = oprofilefs_register();
    +		oprofile_arch_init(&oprofile_ops);
     	}
    - 
    +
    +	err = oprofilefs_register();
     	if (err)
    -		goto out_exit;
    -out:
    +		oprofile_arch_exit();
    +
     	return err;
    -out_exit:
    -	oprofile_arch_exit();
    -	goto out;
     }
     
     
    Index: linux/drivers/oprofile/cpu_buffer.h
    ===================================================================
    --- linux.orig/drivers/oprofile/cpu_buffer.h	2004-10-19 07:55:27.%N +1000
    +++ linux/drivers/oprofile/cpu_buffer.h	2004-11-07 18:00:02.%N +1100
    @@ -37,9 +37,11 @@ struct oprofile_cpu_buffer {
     	unsigned long buffer_size;
     	struct task_struct * last_task;
     	int last_is_kernel;
    +	int tracing;
     	struct op_sample * buffer;
     	unsigned long sample_received;
     	unsigned long sample_lost_overflow;
    +	unsigned long backtrace_aborted;
     	int cpu;
     	struct work_struct work;
     } ____cacheline_aligned;
    @@ -48,4 +50,8 @@ extern struct oprofile_cpu_buffer cpu_bu
     
     void cpu_buffer_reset(struct oprofile_cpu_buffer * cpu_buf);
     
    +/* transient events for the CPU buffer -> event buffer */
    +#define CPU_IS_KERNEL 1
    +#define CPU_TRACE_BEGIN 2
    +
     #endif /* OPROFILE_CPU_BUFFER_H */
    Index: linux/drivers/oprofile/buffer_sync.c
    ===================================================================
    --- linux.orig/drivers/oprofile/buffer_sync.c	2004-10-19 07:53:45.%N +1000
    +++ linux/drivers/oprofile/buffer_sync.c	2004-11-07 18:00:02.%N +1100
    @@ -296,6 +296,13 @@ static void add_cookie_switch(unsigned l
     }
     
      
    +static void add_trace_begin(void)
    +{
    +	add_event_entry(ESCAPE_CODE);
    +	add_event_entry(TRACE_BEGIN_CODE);
    +}
    +
    +
     static void add_sample_entry(unsigned long offset, unsigned long event)
     {
     	add_event_entry(offset);
    @@ -303,7 +310,7 @@ static void add_sample_entry(unsigned lo
     }
     
     
    -static void add_us_sample(struct mm_struct * mm, struct op_sample * s)
    +static int add_us_sample(struct mm_struct * mm, struct op_sample * s)
     {
     	unsigned long cookie;
     	off_t offset;
    @@ -312,7 +319,7 @@ static void add_us_sample(struct mm_stru
      
     	if (!cookie) {
     		atomic_inc(&oprofile_stats.sample_lost_no_mapping);
    -		return;
    +		return 0;
     	}
     
     	if (cookie != last_cookie) {
    @@ -321,6 +328,8 @@ static void add_us_sample(struct mm_stru
     	}
     
     	add_sample_entry(offset, s->event);
    +
    +	return 1;
     }
     
      
    @@ -328,15 +337,18 @@ static void add_us_sample(struct mm_stru
      * sample is converted into a persistent dentry/offset pair
      * for later lookup from userspace.
      */
    -static void add_sample(struct mm_struct * mm, struct op_sample * s, int in_kernel)
    +static int
    +add_sample(struct mm_struct * mm, struct op_sample * s, int in_kernel)
     {
     	if (in_kernel) {
     		add_sample_entry(s->eip, s->event);
    +		return 1;
     	} else if (mm) {
    -		add_us_sample(mm, s);
    +		return add_us_sample(mm, s);
     	} else {
     		atomic_inc(&oprofile_stats.sample_lost_no_mm);
     	}
    +	return 0;
     }
      
     
    @@ -358,9 +370,9 @@ static struct mm_struct * take_tasks_mm(
     }
     
     
    -static inline int is_ctx_switch(unsigned long val)
    +static inline int is_code(unsigned long val)
     {
    -	return val == ~0UL;
    +	return val == ESCAPE_CODE;
     }
      
     
    @@ -397,7 +409,7 @@ static void increment_tail(struct oprofi
     
     	rmb();
     
    -	if (new_tail < (b->buffer_size))
    +	if (new_tail < b->buffer_size)
     		b->tail_pos = new_tail;
     	else
     		b->tail_pos = 0;
    @@ -454,6 +466,17 @@ static void mark_done(int cpu)
     }
     
     
    +/* FIXME: this is not sufficient if we implement syscall barrier backtrace
    + * traversal, the code switch to sb_sample_start at first kernel enter/exit
    + * switch so we need a fifth state and some special handling in sync_buffer()
    + */
    +typedef enum {
    +	sb_bt_ignore = -2,
    +	sb_buffer_start,
    +	sb_bt_start,
    +	sb_sample_start,
    +} sync_buffer_state;
    +
     /* Sync one of the CPU's buffers into the global event buffer.
      * Here we need to go through each batch of samples punctuated
      * by context switch notes, taking the task's mmap_sem and doing
    @@ -468,6 +491,7 @@ void sync_buffer(int cpu)
     	unsigned long cookie = 0;
     	int in_kernel = 1;
     	unsigned int i;
    +	sync_buffer_state state = sb_buffer_start;
     	unsigned long available;
     
     	down(&buffer_sem);
    @@ -478,14 +502,19 @@ void sync_buffer(int cpu)
     
     	available = get_slots(cpu_buf);
     
    -	for (i=0; i < available; ++i) {
    +	for (i = 0; i < available; ++i) {
     		struct op_sample * s = &cpu_buf->buffer[cpu_buf->tail_pos];
      
    -		if (is_ctx_switch(s->eip)) {
    -			if (s->event <= 1) {
    +		if (is_code(s->eip)) {
    +			if (s->event <= CPU_IS_KERNEL) {
     				/* kernel/userspace switch */
     				in_kernel = s->event;
    +				if (state == sb_buffer_start)
    +					state = sb_sample_start;
     				add_kernel_ctx_switch(s->event);
    +			} else if (s->event == CPU_TRACE_BEGIN) {
    +				state = sb_bt_start;
    +				add_trace_begin();
     			} else {
     				struct mm_struct * oldmm = mm;
     
    @@ -499,7 +528,13 @@ void sync_buffer(int cpu)
     				add_user_ctx_switch(new, cookie);
     			}
     		} else {
    -			add_sample(mm, s, in_kernel);
    +			if (state >= sb_bt_start &&
    +			    !add_sample(mm, s, in_kernel)) {
    +				if (state == sb_bt_start) {
    +					state = sb_bt_ignore;
    +					atomic_inc(&oprofile_stats.bt_lost_no_mapping);
    +				}
    +			}
     		}
     
     		increment_tail(cpu_buf);
    Index: linux/drivers/oprofile/timer_int.c
    ===================================================================
    --- linux.orig/drivers/oprofile/timer_int.c	2004-11-07 17:59:34.%N +1100
    +++ linux/drivers/oprofile/timer_int.c	2004-11-07 18:01:50.%N +1100
    @@ -17,10 +17,7 @@
      
     static int timer_notify(struct pt_regs *regs)
     {
    -	int cpu = smp_processor_id();
    -	unsigned long eip = profile_pc(regs);
    - 
    -	oprofile_add_sample(eip, !user_mode(regs), 0, cpu);
    + 	oprofile_add_sample(regs, 0);
     	return 0;
     }
     
    @@ -36,15 +33,9 @@ static void timer_stop(void)
     }
     
     
    -static struct oprofile_operations timer_ops = {
    -	.start	= timer_start,
    -	.stop	= timer_stop,
    -	.cpu_type = "timer"
    -};
    -
    - 
    -void __init timer_init(struct oprofile_operations ** ops)
    +void __init timer_init(struct oprofile_operations * ops)
     {
    -	*ops = &timer_ops;
    -	printk(KERN_INFO "oprofile: using timer interrupt.\n");
    +	ops->start = timer_start;
    +	ops->stop = timer_stop;
    +	ops->cpu_type = "timer";
     }
    Index: linux/drivers/oprofile/oprofile_stats.c
    ===================================================================
    --- linux.orig/drivers/oprofile/oprofile_stats.c	2004-10-19 07:54:39.%N +1000
    +++ linux/drivers/oprofile/oprofile_stats.c	2004-11-07 18:00:02.%N +1100
    @@ -59,6 +59,8 @@ void oprofile_create_stats_files(struct 
     			&cpu_buf->sample_received);
     		oprofilefs_create_ro_ulong(sb, cpudir, "sample_lost_overflow",
     			&cpu_buf->sample_lost_overflow);
    +		oprofilefs_create_ro_ulong(sb, cpudir, "backtrace_aborted",
    +			&cpu_buf->backtrace_aborted);
     	}
      
     	oprofilefs_create_ro_atomic(sb, dir, "sample_lost_no_mm",
    @@ -67,4 +69,6 @@ void oprofile_create_stats_files(struct 
     		&oprofile_stats.sample_lost_no_mapping);
     	oprofilefs_create_ro_atomic(sb, dir, "event_lost_overflow",
     		&oprofile_stats.event_lost_overflow);
    +	oprofilefs_create_ro_atomic(sb, dir, "bt_lost_no_mapping",
    +		&oprofile_stats.bt_lost_no_mapping);
     }
    Index: linux/drivers/oprofile/event_buffer.h
    ===================================================================
    --- linux.orig/drivers/oprofile/event_buffer.h	2004-10-19 07:53:21.%N +1000
    +++ linux/drivers/oprofile/event_buffer.h	2004-11-07 18:00:02.%N +1100
    @@ -32,6 +32,8 @@ void wake_up_buffer_waiter(void);
     #define KERNEL_EXIT_SWITCH_CODE		5
     #define MODULE_LOADED_CODE		6
     #define CTX_TGID_CODE			7
    +#define TRACE_BEGIN_CODE		8
    +#define TRACE_END_CODE			9
      
     /* add data to the event buffer */
     void add_event_entry(unsigned long data);
    Index: linux/drivers/oprofile/oprof.h
    ===================================================================
    --- linux.orig/drivers/oprofile/oprof.h	2004-10-19 07:53:22.%N +1000
    +++ linux/drivers/oprofile/oprof.h	2004-11-07 18:00:02.%N +1100
    @@ -24,12 +24,15 @@ struct oprofile_operations;
     extern unsigned long fs_buffer_size;
     extern unsigned long fs_cpu_buffer_size;
     extern unsigned long fs_buffer_watershed;
    -extern struct oprofile_operations * oprofile_ops;
    +extern struct oprofile_operations oprofile_ops;
     extern unsigned long oprofile_started;
    +extern unsigned long backtrace_depth;
      
     struct super_block;
     struct dentry;
     
     void oprofile_create_files(struct super_block * sb, struct dentry * root);
    +
    +int oprofile_set_backtrace(unsigned long depth);
      
     #endif /* OPROF_H */
    -
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