| /** |
| * @file buffer_sync.c |
| * |
| * @remark Copyright 2002-2009 OProfile authors |
| * @remark Read the file COPYING |
| * |
| * @author John Levon <levon@movementarian.org> |
| * @author Barry Kasindorf |
| * @author Robert Richter <robert.richter@amd.com> |
| * |
| * 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 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); |
| } |
| |
| static void add_data(struct op_entry *entry, struct mm_struct *mm) |
| { |
| unsigned long code, pc, val; |
| unsigned long cookie; |
| off_t offset; |
| |
| if (!op_cpu_buffer_get_data(entry, &code)) |
| return; |
| if (!op_cpu_buffer_get_data(entry, &pc)) |
| return; |
| if (!op_cpu_buffer_get_size(entry)) |
| return; |
| |
| if (mm) { |
| cookie = lookup_dcookie(mm, pc, &offset); |
| |
| if (cookie == NO_COOKIE) |
| offset = pc; |
| if (cookie == INVALID_COOKIE) { |
| atomic_inc(&oprofile_stats.sample_lost_no_mapping); |
| offset = pc; |
| } |
| if (cookie != last_cookie) { |
| add_cookie_switch(cookie); |
| last_cookie = cookie; |
| } |
| } else |
| offset = pc; |
| |
| add_event_entry(ESCAPE_CODE); |
| add_event_entry(code); |
| add_event_entry(offset); /* Offset from Dcookie */ |
| |
| while (op_cpu_buffer_get_data(entry, &val)) |
| add_event_entry(val); |
| } |
| |
| static inline void add_sample_entry(unsigned long offset, unsigned long event) |
| { |
| add_event_entry(offset); |
| add_event_entry(event); |
| } |
| |
| |
| /* |
| * 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. Return 0 on failure. |
| */ |
| static int |
| add_sample(struct mm_struct *mm, struct op_sample *s, int in_kernel) |
| { |
| unsigned long cookie; |
| off_t offset; |
| |
| if (in_kernel) { |
| add_sample_entry(s->eip, s->event); |
| return 1; |
| } |
| |
| /* add userspace sample */ |
| |
| if (!mm) { |
| atomic_inc(&oprofile_stats.sample_lost_no_mm); |
| return 0; |
| } |
| |
| 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; |
| } |
| |
| |
| 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; |
| } |
| |
| |
| /* 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 mm_struct *mm = NULL; |
| struct mm_struct *oldmm; |
| unsigned long val; |
| struct task_struct *new; |
| unsigned long cookie = 0; |
| int in_kernel = 1; |
| sync_buffer_state state = sb_buffer_start; |
| unsigned int i; |
| unsigned long available; |
| unsigned long flags; |
| struct op_entry entry; |
| struct op_sample *sample; |
| |
| mutex_lock(&buffer_mutex); |
| |
| add_cpu_switch(cpu); |
| |
| op_cpu_buffer_reset(cpu); |
| available = op_cpu_buffer_entries(cpu); |
| |
| for (i = 0; i < available; ++i) { |
| sample = op_cpu_buffer_read_entry(&entry, cpu); |
| if (!sample) |
| break; |
| |
| if (is_code(sample->eip)) { |
| flags = sample->event; |
| if (flags & TRACE_BEGIN) { |
| state = sb_bt_start; |
| add_trace_begin(); |
| } |
| if (flags & KERNEL_CTX_SWITCH) { |
| /* kernel/userspace switch */ |
| in_kernel = flags & IS_KERNEL; |
| if (state == sb_buffer_start) |
| state = sb_sample_start; |
| add_kernel_ctx_switch(flags & IS_KERNEL); |
| } |
| if (flags & USER_CTX_SWITCH |
| && op_cpu_buffer_get_data(&entry, &val)) { |
| /* userspace context switch */ |
| new = (struct task_struct *)val; |
| oldmm = mm; |
| release_mm(oldmm); |
| mm = take_tasks_mm(new); |
| if (mm != oldmm) |
| cookie = get_exec_dcookie(mm); |
| add_user_ctx_switch(new, cookie); |
| } |
| if (op_cpu_buffer_get_size(&entry)) |
| add_data(&entry, mm); |
| continue; |
| } |
| |
| if (state < sb_bt_start) |
| /* ignore sample */ |
| continue; |
| |
| if (add_sample(mm, sample, in_kernel)) |
| continue; |
| |
| /* ignore backtraces if failed to add a sample */ |
| if (state == sb_bt_start) { |
| state = sb_bt_ignore; |
| atomic_inc(&oprofile_stats.bt_lost_no_mapping); |
| } |
| } |
| release_mm(mm); |
| |
| mark_done(cpu); |
| |
| mutex_unlock(&buffer_mutex); |
| } |
| |
| /* The function can be used to add a buffer worth of data directly to |
| * the kernel buffer. The buffer is assumed to be a circular buffer. |
| * Take the entries from index start and end at index end, wrapping |
| * at max_entries. |
| */ |
| void oprofile_put_buff(unsigned long *buf, unsigned int start, |
| unsigned int stop, unsigned int max) |
| { |
| int i; |
| |
| i = start; |
| |
| mutex_lock(&buffer_mutex); |
| while (i != stop) { |
| add_event_entry(buf[i++]); |
| |
| if (i >= max) |
| i = 0; |
| } |
| |
| mutex_unlock(&buffer_mutex); |
| } |
| |