/** * @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/file.h>#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 <linux/gfp.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_var_t marked_cpus;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 inttask_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 inttask_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 intmunmap_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 intmodule_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 free_all_tasks(void){ /* make sure we don't leak task structs */ process_task_mortuary(); process_task_mortuary();} int sync_start(void){ int err; if (!zalloc_cpumask_var(&marked_cpus, GFP_KERNEL)) return -ENOMEM; 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; start_cpu_work(); 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); free_all_tasks();out1: free_cpumask_var(marked_cpus); goto out;} void sync_stop(void){ end_cpu_work(); 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); barrier(); /* do all of the above first */ flush_cpu_work(); free_all_tasks(); free_cpumask_var(marked_cpus);} /* 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_flags & DCACHE_COOKIE) return (unsigned long)path->dentry; get_dcookie(path, &cookie); return cookie;} /* Look up the dcookie for the task's mm->exe_file, * 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 file *exe_file; if (!mm) goto done; exe_file = get_mm_exe_file(mm); if (!exe_file) goto done; cookie = fast_get_dcookie(&exe_file->f_path); fput(exe_file);done: 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. * * The caller must ensure the mm is not nil (ie: not a kernel thread). */static unsigned longlookup_dcookie(struct mm_struct *mm, unsigned long addr, off_t *offset){ unsigned long cookie = NO_COOKIE; struct vm_area_struct *vma; down_read(&mm->mmap_sem); 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; up_read(&mm->mmap_sem); 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 voidadd_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 intadd_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; mmput(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; cpumask_set_cpu(cpu, marked_cpus); for_each_online_cpu(i) { if (!cpumask_test_cpu(i, marked_cpus)) return; } /* All CPUs have been processed at least once, * we can process the mortuary once */ process_task_mortuary(); cpumask_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;Lines 1–500 of 589. 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/** * @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/file.h> #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 <linux/gfp.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_var_t marked_cpus; 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 free_all_tasks(void) { /* make sure we don't leak task structs */ process_task_mortuary(); process_task_mortuary(); } int sync_start(void) { int err; if (!zalloc_cpumask_var(&marked_cpus, GFP_KERNEL)) return -ENOMEM; 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; start_cpu_work(); 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); free_all_tasks(); out1: free_cpumask_var(marked_cpus); goto out; } void sync_stop(void) { end_cpu_work(); 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); barrier(); /* do all of the above first */ flush_cpu_work(); free_all_tasks(); free_cpumask_var(marked_cpus); } /* 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_flags & DCACHE_COOKIE) return (unsigned long)path->dentry; get_dcookie(path, &cookie); return cookie; } /* Look up the dcookie for the task's mm->exe_file, * 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 file *exe_file; if (!mm) goto done; exe_file = get_mm_exe_file(mm); if (!exe_file) goto done; cookie = fast_get_dcookie(&exe_file->f_path); fput(exe_file); done: 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. * * The caller must ensure the mm is not nil (ie: not a kernel thread). */ 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; down_read(&mm->mmap_sem); 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; up_read(&mm->mmap_sem); 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; mmput(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; cpumask_set_cpu(cpu, marked_cpus); for_each_online_cpu(i) { if (!cpumask_test_cpu(i, marked_cpus)) return; } /* All CPUs have been processed at least once, * we can process the mortuary once */ process_task_mortuary(); cpumask_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;