| /** |
| * @file buffer_sync.c |
| * |
| * @remark Copyright 2002 OProfile authors |
| * @remark Read the file COPYING |
| * |
| * @author John Levon <levon@movementarian.org> |
| * @author Barry Kasindorf |
| * |
| * This is the core of the buffer management. Each |
| * CPU buffer is processed and entered into the |
| * global event buffer. Such processing is necessary |
| * in several circumstances, mentioned below. |
| * |
| * The processing does the job of converting the |
| * transitory EIP value into a persistent dentry/offset |
| * value that the profiler can record at its leisure. |
| * |
| * See fs/dcookies.c for a description of the dentry/offset |
| * objects. |
| */ |
| |
| #include <linux/mm.h> |
| #include <linux/workqueue.h> |
| #include <linux/notifier.h> |
| #include <linux/dcookies.h> |
| #include <linux/profile.h> |
| #include <linux/module.h> |
| #include <linux/fs.h> |
| #include <linux/oprofile.h> |
| #include <linux/sched.h> |
| |
| #include "oprofile_stats.h" |
| #include "event_buffer.h" |
| #include "cpu_buffer.h" |
| #include "buffer_sync.h" |
| |
| static LIST_HEAD(dying_tasks); |
| static LIST_HEAD(dead_tasks); |
| static cpumask_t marked_cpus = CPU_MASK_NONE; |
| static DEFINE_SPINLOCK(task_mortuary); |
| static void process_task_mortuary(void); |
| |
| /* Take ownership of the task struct and place it on the |
| * list for processing. Only after two full buffer syncs |
| * does the task eventually get freed, because by then |
| * we are sure we will not reference it again. |
| * Can be invoked from softirq via RCU callback due to |
| * call_rcu() of the task struct, hence the _irqsave. |
| */ |
| static int |
| task_free_notify(struct notifier_block *self, unsigned long val, void *data) |
| { |
| unsigned long flags; |
| struct task_struct *task = data; |
| spin_lock_irqsave(&task_mortuary, flags); |
| list_add(&task->tasks, &dying_tasks); |
| spin_unlock_irqrestore(&task_mortuary, flags); |
| return NOTIFY_OK; |
| } |
| |
| |
| /* The task is on its way out. A sync of the buffer means we can catch |
| * any remaining samples for this task. |
| */ |
| static int |
| task_exit_notify(struct notifier_block *self, unsigned long val, void *data) |
| { |
| /* To avoid latency problems, we only process the current CPU, |
| * hoping that most samples for the task are on this CPU |
| */ |
| sync_buffer(raw_smp_processor_id()); |
| return 0; |
| } |
| |
| |
| /* The task is about to try a do_munmap(). We peek at what it's going to |
| * do, and if it's an executable region, process the samples first, so |
| * we don't lose any. This does not have to be exact, it's a QoI issue |
| * only. |
| */ |
| static int |
| munmap_notify(struct notifier_block *self, unsigned long val, void *data) |
| { |
| unsigned long addr = (unsigned long)data; |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *mpnt; |
| |
| down_read(&mm->mmap_sem); |
| |
| mpnt = find_vma(mm, addr); |
| if (mpnt && mpnt->vm_file && (mpnt->vm_flags & VM_EXEC)) { |
| up_read(&mm->mmap_sem); |
| /* To avoid latency problems, we only process the current CPU, |
| * hoping that most samples for the task are on this CPU |
| */ |
| sync_buffer(raw_smp_processor_id()); |
| return 0; |
| } |
| |
| up_read(&mm->mmap_sem); |
| return 0; |
| } |
| |
| |
| /* We need to be told about new modules so we don't attribute to a previously |
| * loaded module, or drop the samples on the floor. |
| */ |
| static int |
| module_load_notify(struct notifier_block *self, unsigned long val, void *data) |
| { |
| #ifdef CONFIG_MODULES |
| if (val != MODULE_STATE_COMING) |
| return 0; |
| |
| /* FIXME: should we process all CPU buffers ? */ |
| mutex_lock(&buffer_mutex); |
| add_event_entry(ESCAPE_CODE); |
| add_event_entry(MODULE_LOADED_CODE); |
| mutex_unlock(&buffer_mutex); |
| #endif |
| return 0; |
| } |
| |
| |
| static struct notifier_block task_free_nb = { |
| .notifier_call = task_free_notify, |
| }; |
| |
| static struct notifier_block task_exit_nb = { |
| .notifier_call = task_exit_notify, |
| }; |
| |
| static struct notifier_block munmap_nb = { |
| .notifier_call = munmap_notify, |
| }; |
| |
| static struct notifier_block module_load_nb = { |
| .notifier_call = module_load_notify, |
| }; |
| |
| |
| static void end_sync(void) |
| { |
| end_cpu_work(); |
| /* make sure we don't leak task structs */ |
| process_task_mortuary(); |
| process_task_mortuary(); |
| } |
| |
| |
| int sync_start(void) |
| { |
| int err; |
| |
| start_cpu_work(); |
| |
| err = task_handoff_register(&task_free_nb); |
| if (err) |
| goto out1; |
| err = profile_event_register(PROFILE_TASK_EXIT, &task_exit_nb); |
| if (err) |
| goto out2; |
| err = profile_event_register(PROFILE_MUNMAP, &munmap_nb); |
| if (err) |
| goto out3; |
| err = register_module_notifier(&module_load_nb); |
| if (err) |
| goto out4; |
| |
| out: |
| return err; |
| out4: |
| profile_event_unregister(PROFILE_MUNMAP, &munmap_nb); |
| out3: |
| profile_event_unregister(PROFILE_TASK_EXIT, &task_exit_nb); |
| out2: |
| task_handoff_unregister(&task_free_nb); |
| out1: |
| end_sync(); |
| goto out; |
| } |
| |
| |
| void sync_stop(void) |
| { |
| unregister_module_notifier(&module_load_nb); |
| profile_event_unregister(PROFILE_MUNMAP, &munmap_nb); |
| profile_event_unregister(PROFILE_TASK_EXIT, &task_exit_nb); |
| task_handoff_unregister(&task_free_nb); |
| end_sync(); |
| } |
| |
| |
| /* Optimisation. We can manage without taking the dcookie sem |
| * because we cannot reach this code without at least one |
| * dcookie user still being registered (namely, the reader |
| * of the event buffer). */ |
| static inline unsigned long fast_get_dcookie(struct path *path) |
| { |
| unsigned long cookie; |
| |
| if (path->dentry->d_cookie) |
| return (unsigned long)path->dentry; |
| get_dcookie(path, &cookie); |
| return cookie; |
| } |
| |
| |
| /* Look up the dcookie for the task's first VM_EXECUTABLE mapping, |
| * which corresponds loosely to "application name". This is |
| * not strictly necessary but allows oprofile to associate |
| * shared-library samples with particular applications |
| */ |
| static unsigned long get_exec_dcookie(struct mm_struct *mm) |
| { |
| unsigned long cookie = NO_COOKIE; |
| struct vm_area_struct *vma; |
| |
| if (!mm) |
| goto out; |
| |
| for (vma = mm->mmap; vma; vma = vma->vm_next) { |
| if (!vma->vm_file) |
| continue; |
| if (!(vma->vm_flags & VM_EXECUTABLE)) |
| continue; |
| cookie = fast_get_dcookie(&vma->vm_file->f_path); |
| break; |
| } |
| |
| out: |
| return cookie; |
| } |
| |
| |
| /* Convert the EIP value of a sample into a persistent dentry/offset |
| * pair that can then be added to the global event buffer. We make |
| * sure to do this lookup before a mm->mmap modification happens so |
| * we don't lose track. |
| */ |
| static unsigned long |
| lookup_dcookie(struct mm_struct *mm, unsigned long addr, off_t *offset) |
| { |
| unsigned long cookie = NO_COOKIE; |
| struct vm_area_struct *vma; |
| |
| for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) { |
| |
| if (addr < vma->vm_start || addr >= vma->vm_end) |
| continue; |
| |
| if (vma->vm_file) { |
| cookie = fast_get_dcookie(&vma->vm_file->f_path); |
| *offset = (vma->vm_pgoff << PAGE_SHIFT) + addr - |
| vma->vm_start; |
| } else { |
| /* must be an anonymous map */ |
| *offset = addr; |
| } |
| |
| break; |
| } |
| |
| if (!vma) |
| cookie = INVALID_COOKIE; |
| |
| return cookie; |
| } |
| |
| static void increment_tail(struct oprofile_cpu_buffer *b) |
| { |
| unsigned long new_tail = b->tail_pos + 1; |
| |
| rmb(); /* be sure fifo pointers are synchromized */ |
| |
| if (new_tail < b->buffer_size) |
| b->tail_pos = new_tail; |
| else |
| b->tail_pos = 0; |
| } |
| |
| static unsigned long last_cookie = INVALID_COOKIE; |
| |
| static void add_cpu_switch(int i) |
| { |
| add_event_entry(ESCAPE_CODE); |
| add_event_entry(CPU_SWITCH_CODE); |
| add_event_entry(i); |
| last_cookie = INVALID_COOKIE; |
| } |
| |
| static void add_kernel_ctx_switch(unsigned int in_kernel) |
| { |
| add_event_entry(ESCAPE_CODE); |
| if (in_kernel) |
| add_event_entry(KERNEL_ENTER_SWITCH_CODE); |
| else |
| add_event_entry(KERNEL_EXIT_SWITCH_CODE); |
| } |
| |
| static void |
| add_user_ctx_switch(struct task_struct const *task, unsigned long cookie) |
| { |
| add_event_entry(ESCAPE_CODE); |
| add_event_entry(CTX_SWITCH_CODE); |
| add_event_entry(task->pid); |
| add_event_entry(cookie); |
| /* Another code for daemon back-compat */ |
| add_event_entry(ESCAPE_CODE); |
| add_event_entry(CTX_TGID_CODE); |
| add_event_entry(task->tgid); |
| } |
| |
| |
| static void add_cookie_switch(unsigned long cookie) |
| { |
| add_event_entry(ESCAPE_CODE); |
| add_event_entry(COOKIE_SWITCH_CODE); |
| add_event_entry(cookie); |
| } |
| |
| |
| static void add_trace_begin(void) |
| { |
| add_event_entry(ESCAPE_CODE); |
| add_event_entry(TRACE_BEGIN_CODE); |
| } |
| |
| #ifdef CONFIG_OPROFILE_IBS |
| |
| #define IBS_FETCH_CODE_SIZE 2 |
| #define IBS_OP_CODE_SIZE 5 |
| #define IBS_EIP(offset) \ |
| (((struct op_sample *)&cpu_buf->buffer[(offset)])->eip) |
| #define IBS_EVENT(offset) \ |
| (((struct op_sample *)&cpu_buf->buffer[(offset)])->event) |
| |
| /* |
| * Add IBS fetch and op entries to event buffer |
| */ |
| static void add_ibs_begin(struct oprofile_cpu_buffer *cpu_buf, int code, |
| int in_kernel, struct mm_struct *mm) |
| { |
| unsigned long rip; |
| int i, count; |
| unsigned long ibs_cookie = 0; |
| off_t offset; |
| |
| increment_tail(cpu_buf); /* move to RIP entry */ |
| |
| rip = IBS_EIP(cpu_buf->tail_pos); |
| |
| #ifdef __LP64__ |
| rip += IBS_EVENT(cpu_buf->tail_pos) << 32; |
| #endif |
| |
| if (mm) { |
| ibs_cookie = lookup_dcookie(mm, rip, &offset); |
| |
| if (ibs_cookie == NO_COOKIE) |
| offset = rip; |
| if (ibs_cookie == INVALID_COOKIE) { |
| atomic_inc(&oprofile_stats.sample_lost_no_mapping); |
| offset = rip; |
| } |
| if (ibs_cookie != last_cookie) { |
| add_cookie_switch(ibs_cookie); |
| last_cookie = ibs_cookie; |
| } |
| } else |
| offset = rip; |
| |
| add_event_entry(ESCAPE_CODE); |
| add_event_entry(code); |
| add_event_entry(offset); /* Offset from Dcookie */ |
| |
| /* we send the Dcookie offset, but send the raw Linear Add also*/ |
| add_event_entry(IBS_EIP(cpu_buf->tail_pos)); |
| add_event_entry(IBS_EVENT(cpu_buf->tail_pos)); |
| |
| if (code == IBS_FETCH_CODE) |
| count = IBS_FETCH_CODE_SIZE; /*IBS FETCH is 2 int64s*/ |
| else |
| count = IBS_OP_CODE_SIZE; /*IBS OP is 5 int64s*/ |
| |
| for (i = 0; i < count; i++) { |
| increment_tail(cpu_buf); |
| add_event_entry(IBS_EIP(cpu_buf->tail_pos)); |
| add_event_entry(IBS_EVENT(cpu_buf->tail_pos)); |
| } |
| } |
| |
| #endif |
| |
| static void add_sample_entry(unsigned long offset, unsigned long event) |
| { |
| add_event_entry(offset); |
| add_event_entry(event); |
| } |
| |
| |
| static int add_us_sample(struct mm_struct *mm, struct op_sample *s) |
| { |
| unsigned long cookie; |
| off_t offset; |
| |
| cookie = lookup_dcookie(mm, s->eip, &offset); |
| |
| if (cookie == INVALID_COOKIE) { |
| atomic_inc(&oprofile_stats.sample_lost_no_mapping); |
| return 0; |
| } |
| |
| if (cookie != last_cookie) { |
| add_cookie_switch(cookie); |
| last_cookie = cookie; |
| } |
| |
| add_sample_entry(offset, s->event); |
| |
| return 1; |
| } |
| |
| |
| /* Add a sample to the global event buffer. If possible the |
| * sample is converted into a persistent dentry/offset pair |
| * for later lookup from userspace. |
| */ |
| 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) { |
| return add_us_sample(mm, s); |
| } else { |
| atomic_inc(&oprofile_stats.sample_lost_no_mm); |
| } |
| return 0; |
| } |
| |
| |
| static void release_mm(struct mm_struct *mm) |
| { |
| if (!mm) |
| return; |
| up_read(&mm->mmap_sem); |
| mmput(mm); |
| } |
| |
| |
| static struct mm_struct *take_tasks_mm(struct task_struct *task) |
| { |
| struct mm_struct *mm = get_task_mm(task); |
| if (mm) |
| down_read(&mm->mmap_sem); |
| return mm; |
| } |
| |
| |
| static inline int is_code(unsigned long val) |
| { |
| return val == ESCAPE_CODE; |
| } |
| |
| |
| /* "acquire" as many cpu buffer slots as we can */ |
| static unsigned long get_slots(struct oprofile_cpu_buffer *b) |
| { |
| unsigned long head = b->head_pos; |
| unsigned long tail = b->tail_pos; |
| |
| /* |
| * Subtle. This resets the persistent last_task |
| * and in_kernel values used for switching notes. |
| * BUT, there is a small window between reading |
| * head_pos, and this call, that means samples |
| * can appear at the new head position, but not |
| * be prefixed with the notes for switching |
| * kernel mode or a task switch. This small hole |
| * can lead to mis-attribution or samples where |
| * we don't know if it's in the kernel or not, |
| * at the start of an event buffer. |
| */ |
| cpu_buffer_reset(b); |
| |
| if (head >= tail) |
| return head - tail; |
| |
| return head + (b->buffer_size - tail); |
| } |
| |
| |
| /* Move tasks along towards death. Any tasks on dead_tasks |
| * will definitely have no remaining references in any |
| * CPU buffers at this point, because we use two lists, |
| * and to have reached the list, it must have gone through |
| * one full sync already. |
| */ |
| static void process_task_mortuary(void) |
| { |
| unsigned long flags; |
| LIST_HEAD(local_dead_tasks); |
| struct task_struct *task; |
| struct task_struct *ttask; |
| |
| spin_lock_irqsave(&task_mortuary, flags); |
| |
| list_splice_init(&dead_tasks, &local_dead_tasks); |
| list_splice_init(&dying_tasks, &dead_tasks); |
| |
| spin_unlock_irqrestore(&task_mortuary, flags); |
| |
| list_for_each_entry_safe(task, ttask, &local_dead_tasks, tasks) { |
| list_del(&task->tasks); |
| free_task(task); |
| } |
| } |
| |
| |
| static void mark_done(int cpu) |
| { |
| int i; |
| |
| cpu_set(cpu, marked_cpus); |
| |
| for_each_online_cpu(i) { |
| if (!cpu_isset(i, marked_cpus)) |
| return; |
| } |
| |
| /* All CPUs have been processed at least once, |
| * we can process the mortuary once |
| */ |
| process_task_mortuary(); |
| |
| cpus_clear(marked_cpus); |
| } |
| |
| |
| /* 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 |
| * lookup in task->mm->mmap to convert EIP into dcookie/offset |
| * value. |
| */ |
| void sync_buffer(int cpu) |
| { |
| struct oprofile_cpu_buffer *cpu_buf = &per_cpu(cpu_buffer, cpu); |
| struct mm_struct *mm = NULL; |
| struct task_struct *new; |
| unsigned long cookie = 0; |
| int in_kernel = 1; |
| unsigned int i; |
| sync_buffer_state state = sb_buffer_start; |
| unsigned long available; |
| |
| mutex_lock(&buffer_mutex); |
| |
| add_cpu_switch(cpu); |
| |
| /* Remember, only we can modify tail_pos */ |
| |
| available = get_slots(cpu_buf); |
| |
| for (i = 0; i < available; ++i) { |
| struct op_sample *s = &cpu_buf->buffer[cpu_buf->tail_pos]; |
| |
| 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(); |
| #ifdef CONFIG_OPROFILE_IBS |
| } else if (s->event == IBS_FETCH_BEGIN) { |
| state = sb_bt_start; |
| add_ibs_begin(cpu_buf, |
| IBS_FETCH_CODE, in_kernel, mm); |
| } else if (s->event == IBS_OP_BEGIN) { |
| state = sb_bt_start; |
| add_ibs_begin(cpu_buf, |
| IBS_OP_CODE, in_kernel, mm); |
| #endif |
| } else { |
| struct mm_struct *oldmm = mm; |
| |
| /* userspace context switch */ |
| new = (struct task_struct *)s->event; |
| |
| release_mm(oldmm); |
| mm = take_tasks_mm(new); |
| if (mm != oldmm) |
| cookie = get_exec_dcookie(mm); |
| add_user_ctx_switch(new, cookie); |
| } |
| } else 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); |
| } |
| release_mm(mm); |
| |
| mark_done(cpu); |
| |
| mutex_unlock(&buffer_mutex); |
| } |