diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/Kconfig | 15 | ||||
| -rw-r--r-- | kernel/trace/fgraph.c | 26 | ||||
| -rw-r--r-- | kernel/trace/ftrace.c | 37 | ||||
| -rw-r--r-- | kernel/trace/trace.h | 2 | ||||
| -rw-r--r-- | kernel/trace/trace_boot.c | 8 | ||||
| -rw-r--r-- | kernel/trace/trace_entries.h | 26 | ||||
| -rw-r--r-- | kernel/trace/trace_functions_graph.c | 93 | ||||
| -rw-r--r-- | kernel/trace/trace_osnoise.c | 477 | ||||
| -rw-r--r-- | kernel/trace/trace_output.c | 4 |
9 files changed, 665 insertions, 23 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 8cf97fa4a4b3..abe5c583bd59 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -31,6 +31,9 @@ config HAVE_FUNCTION_GRAPH_TRACER help See Documentation/trace/ftrace-design.rst +config HAVE_FUNCTION_GRAPH_RETVAL + bool + config HAVE_DYNAMIC_FTRACE bool help @@ -227,6 +230,18 @@ config FUNCTION_GRAPH_TRACER the return value. This is done by setting the current return address on the current task structure into a stack of calls. +config FUNCTION_GRAPH_RETVAL + bool "Kernel Function Graph Return Value" + depends on HAVE_FUNCTION_GRAPH_RETVAL + depends on FUNCTION_GRAPH_TRACER + default n + help + Support recording and printing the function return value when + using function graph tracer. It can be helpful to locate functions + that return errors. This feature is off by default, and you can + enable it via the trace option funcgraph-retval. + See Documentation/trace/ftrace.rst + config DYNAMIC_FTRACE bool "enable/disable function tracing dynamically" depends on FUNCTION_TRACER diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index 218cd95bf8e4..cd2c35b1dd8f 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -236,16 +236,23 @@ static struct notifier_block ftrace_suspend_notifier = { .notifier_call = ftrace_suspend_notifier_call, }; +/* fgraph_ret_regs is not defined without CONFIG_FUNCTION_GRAPH_RETVAL */ +struct fgraph_ret_regs; + /* * Send the trace to the ring-buffer. * @return the original return address. */ -unsigned long ftrace_return_to_handler(unsigned long frame_pointer) +static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs, + unsigned long frame_pointer) { struct ftrace_graph_ret trace; unsigned long ret; ftrace_pop_return_trace(&trace, &ret, frame_pointer); +#ifdef CONFIG_FUNCTION_GRAPH_RETVAL + trace.retval = fgraph_ret_regs_return_value(ret_regs); +#endif trace.rettime = trace_clock_local(); ftrace_graph_return(&trace); /* @@ -266,6 +273,23 @@ unsigned long ftrace_return_to_handler(unsigned long frame_pointer) return ret; } +/* + * After all architecures have selected HAVE_FUNCTION_GRAPH_RETVAL, we can + * leave only ftrace_return_to_handler(ret_regs). + */ +#ifdef CONFIG_HAVE_FUNCTION_GRAPH_RETVAL +unsigned long ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs) +{ + return __ftrace_return_to_handler(ret_regs, + fgraph_ret_regs_frame_pointer(ret_regs)); +} +#else +unsigned long ftrace_return_to_handler(unsigned long frame_pointer) +{ + return __ftrace_return_to_handler(NULL, frame_pointer); +} +#endif + /** * ftrace_graph_get_ret_stack - return the entry of the shadow stack * @task: The task to read the shadow stack from diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 6a77edb51f18..3740aca79fe7 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3861,6 +3861,9 @@ static int t_show(struct seq_file *m, void *v) if (!rec) return 0; + if (iter->flags & FTRACE_ITER_ADDRS) + seq_printf(m, "%lx ", rec->ip); + if (print_rec(m, rec->ip)) { /* This should only happen when a rec is disabled */ WARN_ON_ONCE(!(rec->flags & FTRACE_FL_DISABLED)); @@ -3996,6 +3999,30 @@ ftrace_touched_open(struct inode *inode, struct file *file) return 0; } +static int +ftrace_avail_addrs_open(struct inode *inode, struct file *file) +{ + struct ftrace_iterator *iter; + int ret; + + ret = security_locked_down(LOCKDOWN_TRACEFS); + if (ret) + return ret; + + if (unlikely(ftrace_disabled)) + return -ENODEV; + + iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter)); + if (!iter) + return -ENOMEM; + + iter->pg = ftrace_pages_start; + iter->flags = FTRACE_ITER_ADDRS; + iter->ops = &global_ops; + + return 0; +} + /** * ftrace_regex_open - initialize function tracer filter files * @ops: The ftrace_ops that hold the hash filters @@ -5916,6 +5943,13 @@ static const struct file_operations ftrace_touched_fops = { .release = seq_release_private, }; +static const struct file_operations ftrace_avail_addrs_fops = { + .open = ftrace_avail_addrs_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release_private, +}; + static const struct file_operations ftrace_filter_fops = { .open = ftrace_filter_open, .read = seq_read, @@ -6377,6 +6411,9 @@ static __init int ftrace_init_dyn_tracefs(struct dentry *d_tracer) trace_create_file("available_filter_functions", TRACE_MODE_READ, d_tracer, NULL, &ftrace_avail_fops); + trace_create_file("available_filter_functions_addrs", TRACE_MODE_READ, + d_tracer, NULL, &ftrace_avail_addrs_fops); + trace_create_file("enabled_functions", TRACE_MODE_READ, d_tracer, NULL, &ftrace_enabled_fops); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 79bdefe9261b..e6407a27d644 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -832,6 +832,8 @@ static __always_inline bool ftrace_hash_empty(struct ftrace_hash *hash) #define TRACE_GRAPH_PRINT_TAIL 0x100 #define TRACE_GRAPH_SLEEP_TIME 0x200 #define TRACE_GRAPH_GRAPH_TIME 0x400 +#define TRACE_GRAPH_PRINT_RETVAL 0x800 +#define TRACE_GRAPH_PRINT_RETVAL_HEX 0x1000 #define TRACE_GRAPH_PRINT_FILL_SHIFT 28 #define TRACE_GRAPH_PRINT_FILL_MASK (0x3 << TRACE_GRAPH_PRINT_FILL_SHIFT) diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c index 778200dd8ede..5fe525f1b8cc 100644 --- a/kernel/trace/trace_boot.c +++ b/kernel/trace/trace_boot.c @@ -31,7 +31,7 @@ trace_boot_set_instance_options(struct trace_array *tr, struct xbc_node *node) /* Common ftrace options */ xbc_node_for_each_array_value(node, "options", anode, p) { - if (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf)) { + if (strscpy(buf, p, ARRAY_SIZE(buf)) == -E2BIG) { pr_err("String is too long: %s\n", p); continue; } @@ -87,7 +87,7 @@ trace_boot_enable_events(struct trace_array *tr, struct xbc_node *node) const char *p; xbc_node_for_each_array_value(node, "events", anode, p) { - if (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf)) { + if (strscpy(buf, p, ARRAY_SIZE(buf)) == -E2BIG) { pr_err("String is too long: %s\n", p); continue; } @@ -486,7 +486,7 @@ trace_boot_init_one_event(struct trace_array *tr, struct xbc_node *gnode, p = xbc_node_find_value(enode, "filter", NULL); if (p && *p != '\0') { - if (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf)) + if (strscpy(buf, p, ARRAY_SIZE(buf)) == -E2BIG) pr_err("filter string is too long: %s\n", p); else if (apply_event_filter(file, buf) < 0) pr_err("Failed to apply filter: %s\n", buf); @@ -494,7 +494,7 @@ trace_boot_init_one_event(struct trace_array *tr, struct xbc_node *gnode, if (IS_ENABLED(CONFIG_HIST_TRIGGERS)) { xbc_node_for_each_array_value(enode, "actions", anode, p) { - if (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf)) + if (strscpy(buf, p, ARRAY_SIZE(buf)) == -E2BIG) pr_err("action string is too long: %s\n", p); else if (trigger_process_regex(file, buf) < 0) pr_err("Failed to apply an action: %s\n", p); diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h index cd41e863b51c..340b2fa98218 100644 --- a/kernel/trace/trace_entries.h +++ b/kernel/trace/trace_entries.h @@ -86,6 +86,30 @@ FTRACE_ENTRY_PACKED(funcgraph_entry, ftrace_graph_ent_entry, ); /* Function return entry */ +#ifdef CONFIG_FUNCTION_GRAPH_RETVAL + +FTRACE_ENTRY_PACKED(funcgraph_exit, ftrace_graph_ret_entry, + + TRACE_GRAPH_RET, + + F_STRUCT( + __field_struct( struct ftrace_graph_ret, ret ) + __field_packed( unsigned long, ret, func ) + __field_packed( unsigned long, ret, retval ) + __field_packed( int, ret, depth ) + __field_packed( unsigned int, ret, overrun ) + __field_packed( unsigned long long, ret, calltime) + __field_packed( unsigned long long, ret, rettime ) + ), + + F_printk("<-- %ps (%d) (start: %llx end: %llx) over: %d retval: %lx", + (void *)__entry->func, __entry->depth, + __entry->calltime, __entry->rettime, + __entry->depth, __entry->retval) +); + +#else + FTRACE_ENTRY_PACKED(funcgraph_exit, ftrace_graph_ret_entry, TRACE_GRAPH_RET, @@ -105,6 +129,8 @@ FTRACE_ENTRY_PACKED(funcgraph_exit, ftrace_graph_ret_entry, __entry->depth) ); +#endif + /* * Context switch trace entry - which task (and prio) we switched from/to: * diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index 203204cadf92..c35fbaab2a47 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -58,6 +58,12 @@ static struct tracer_opt trace_opts[] = { { TRACER_OPT(funcgraph-irqs, TRACE_GRAPH_PRINT_IRQS) }, /* Display function name after trailing } */ { TRACER_OPT(funcgraph-tail, TRACE_GRAPH_PRINT_TAIL) }, +#ifdef CONFIG_FUNCTION_GRAPH_RETVAL + /* Display function return value ? */ + { TRACER_OPT(funcgraph-retval, TRACE_GRAPH_PRINT_RETVAL) }, + /* Display function return value in hexadecimal format ? */ + { TRACER_OPT(funcgraph-retval-hex, TRACE_GRAPH_PRINT_RETVAL_HEX) }, +#endif /* Include sleep time (scheduled out) between entry and return */ { TRACER_OPT(sleep-time, TRACE_GRAPH_SLEEP_TIME) }, @@ -619,6 +625,56 @@ print_graph_duration(struct trace_array *tr, unsigned long long duration, trace_seq_puts(s, "| "); } +#ifdef CONFIG_FUNCTION_GRAPH_RETVAL + +#define __TRACE_GRAPH_PRINT_RETVAL TRACE_GRAPH_PRINT_RETVAL + +static void print_graph_retval(struct trace_seq *s, unsigned long retval, + bool leaf, void *func, bool hex_format) +{ + unsigned long err_code = 0; + + if (retval == 0 || hex_format) + goto done; + + /* Check if the return value matches the negative format */ + if (IS_ENABLED(CONFIG_64BIT) && (retval & BIT(31)) && + (((u64)retval) >> 32) == 0) { + /* sign extension */ + err_code = (unsigned long)(s32)retval; + } else { + err_code = retval; + } + + if (!IS_ERR_VALUE(err_code)) + err_code = 0; + +done: + if (leaf) { + if (hex_format || (err_code == 0)) + trace_seq_printf(s, "%ps(); /* = 0x%lx */\n", + func, retval); + else + trace_seq_printf(s, "%ps(); /* = %ld */\n", + func, err_code); + } else { + if (hex_format || (err_code == 0)) + trace_seq_printf(s, "} /* %ps = 0x%lx */\n", + func, retval); + else + trace_seq_printf(s, "} /* %ps = %ld */\n", + func, err_code); + } +} + +#else + +#define __TRACE_GRAPH_PRINT_RETVAL 0 + +#define print_graph_retval(_seq, _retval, _leaf, _func, _format) do {} while (0) + +#endif + /* Case of a leaf function on its call entry */ static enum print_line_t print_graph_entry_leaf(struct trace_iterator *iter, @@ -663,7 +719,15 @@ print_graph_entry_leaf(struct trace_iterator *iter, for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) trace_seq_putc(s, ' '); - trace_seq_printf(s, "%ps();\n", (void *)call->func); + /* + * Write out the function return value if the option function-retval is + * enabled. + */ + if (flags & __TRACE_GRAPH_PRINT_RETVAL) + print_graph_retval(s, graph_ret->retval, true, (void *)call->func, + !!(flags & TRACE_GRAPH_PRINT_RETVAL_HEX)); + else + trace_seq_printf(s, "%ps();\n", (void *)call->func); print_graph_irq(iter, graph_ret->func, TRACE_GRAPH_RET, cpu, iter->ent->pid, flags); @@ -942,16 +1006,25 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s, trace_seq_putc(s, ' '); /* - * If the return function does not have a matching entry, - * then the entry was lost. Instead of just printing - * the '}' and letting the user guess what function this - * belongs to, write out the function name. Always do - * that if the funcgraph-tail option is enabled. + * Always write out the function name and its return value if the + * function-retval option is enabled. */ - if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL)) - trace_seq_puts(s, "}\n"); - else - trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func); + if (flags & __TRACE_GRAPH_PRINT_RETVAL) { + print_graph_retval(s, trace->retval, false, (void *)trace->func, + !!(flags & TRACE_GRAPH_PRINT_RETVAL_HEX)); + } else { + /* + * If the return function does not have a matching entry, + * then the entry was lost. Instead of just printing + * the '}' and letting the user guess what function this + * belongs to, write out the function name. Always do + * that if the funcgraph-tail option is enabled. + */ + if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL)) + trace_seq_puts(s, "}\n"); + else + trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func); + } /* Overrun */ if (flags & TRACE_GRAPH_PRINT_OVERRUN) diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index e97e3fa5cbed..bd0d01d00fb9 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -181,6 +181,7 @@ struct osn_irq { #define IRQ_CONTEXT 0 #define THREAD_CONTEXT 1 +#define THREAD_URET 2 /* * sofirq runtime info. */ @@ -238,6 +239,7 @@ struct timerlat_variables { u64 abs_period; bool tracing_thread; u64 count; + bool uthread_migrate; }; static DEFINE_PER_CPU(struct timerlat_variables, per_cpu_timerlat_var); @@ -1181,6 +1183,78 @@ thread_exit(struct osnoise_variables *osn_var, struct task_struct *t) osn_var->thread.arrival_time = 0; } +#ifdef CONFIG_TIMERLAT_TRACER +/* + * osnoise_stop_exception - Stop tracing and the tracer. + */ +static __always_inline void osnoise_stop_exception(char *msg, int cpu) +{ + struct osnoise_instance *inst; + struct trace_array *tr; + + rcu_read_lock(); + list_for_each_entry_rcu(inst, &osnoise_instances, list) { + tr = inst->tr; + trace_array_printk_buf(tr->array_buffer.buffer, _THIS_IP_, + "stop tracing hit on cpu %d due to exception: %s\n", + smp_processor_id(), + msg); + + if (test_bit(OSN_PANIC_ON_STOP, &osnoise_options)) + panic("tracer hit on cpu %d due to exception: %s\n", + smp_processor_id(), + msg); + + tracer_tracing_off(tr); + } + rcu_read_unlock(); +} + +/* + * trace_sched_migrate_callback - sched:sched_migrate_task trace event handler + * + * his function is hooked to the sched:sched_migrate_task trace event, and monitors + * timerlat user-space thread migration. + */ +static void trace_sched_migrate_callback(void *data, struct task_struct *p, int dest_cpu) +{ + struct osnoise_variables *osn_var; + long cpu = task_cpu(p); + + osn_var = per_cpu_ptr(&per_cpu_osnoise_var, cpu); + if (osn_var->pid == p->pid && dest_cpu != cpu) { + per_cpu_ptr(&per_cpu_timerlat_var, cpu)->uthread_migrate = 1; + osnoise_taint("timerlat user-thread migrated\n"); + osnoise_stop_exception("timerlat user-thread migrated", cpu); + } +} + +static int register_migration_monitor(void) +{ + int ret = 0; + + /* + * Timerlat thread migration check is only required when running timerlat in user-space. + * Thus, enable callback only if timerlat is set with no workload. + */ + if (timerlat_enabled() && !test_bit(OSN_WORKLOAD, &osnoise_options)) + ret = register_trace_sched_migrate_task(trace_sched_migrate_callback, NULL); + + return ret; +} + +static void unregister_migration_monitor(void) +{ + if (timerlat_enabled() && !test_bit(OSN_WORKLOAD, &osnoise_options)) + unregister_trace_sched_migrate_task(trace_sched_migrate_callback, NULL); +} +#else +static int register_migration_monitor(void) +{ + return 0; +} +static void unregister_migration_monitor(void) {} +#endif /* * trace_sched_switch - sched:sched_switch trace event handler * @@ -1204,7 +1278,7 @@ trace_sched_switch_callback(void *data, bool preempt, } /* - * hook_thread_events - Hook the insturmentation for thread noise + * hook_thread_events - Hook the instrumentation for thread noise * * Hook the osnoise tracer callbacks to handle the noise from other * threads on the necessary kernel events. @@ -1217,11 +1291,19 @@ static int hook_thread_events(void) if (ret) return -EINVAL; + ret = register_migration_monitor(); + if (ret) + goto out_unreg; + return 0; + +out_unreg: + unregister_trace_sched_switch(trace_sched_switch_callback, NULL); + return -EINVAL; } /* - * unhook_thread_events - *nhook the insturmentation for thread noise + * unhook_thread_events - unhook the instrumentation for thread noise * * Unook the osnoise tracer callbacks to handle the noise from other * threads on the necessary kernel events. @@ -1229,6 +1311,7 @@ static int hook_thread_events(void) static void unhook_thread_events(void) { unregister_trace_sched_switch(trace_sched_switch_callback, NULL); + unregister_migration_monitor(); } /* @@ -1286,6 +1369,22 @@ static __always_inline void osnoise_stop_tracing(void) } /* + * osnoise_has_tracing_on - Check if there is at least one instance on + */ +static __always_inline int osnoise_has_tracing_on(void) +{ + struct osnoise_instance *inst; + int trace_is_on = 0; + + rcu_read_lock(); + list_for_each_entry_rcu(inst, &osnoise_instances, list) + trace_is_on += tracer_tracing_is_on(inst->tr); + rcu_read_unlock(); + + return trace_is_on; +} + +/* * notify_new_max_latency - Notify a new max latency via fsnotify interface. */ static void notify_new_max_latency(u64 latency) @@ -1517,13 +1616,16 @@ static struct cpumask save_cpumask; /* * osnoise_sleep - sleep until the next period */ -static void osnoise_sleep(void) +static void osnoise_sleep(bool skip_period) { u64 interval; ktime_t wake_time; mutex_lock(&interface_lock); - interval = osnoise_data.sample_period - osnoise_data.sample_runtime; + if (skip_period) + interval = osnoise_data.sample_period; + else + interval = osnoise_data.sample_period - osnoise_data.sample_runtime; mutex_unlock(&interface_lock); /* @@ -1546,6 +1648,39 @@ static void osnoise_sleep(void) } /* + * osnoise_migration_pending - checks if the task needs to migrate + * + * osnoise/timerlat threads are per-cpu. If there is a pending request to + * migrate the thread away from the current CPU, something bad has happened. + * Play the good citizen and leave. + * + * Returns 0 if it is safe to continue, 1 otherwise. + */ +static inline int osnoise_migration_pending(void) +{ + if (!current->migration_pending) + return 0; + + /* + * If migration is pending, there is a task waiting for the + * tracer to enable migration. The tracer does not allow migration, + * thus: taint and leave to unblock the blocked thread. + */ + osnoise_taint("migration requested to osnoise threads, leaving."); + + /* + * Unset this thread from the threads managed by the interface. + * The tracers are responsible for cleaning their env before + * exiting. + */ + mutex_lock(&interface_lock); + this_cpu_osn_var()->kthread = NULL; + mutex_unlock(&interface_lock); + + return 1; +} + +/* * osnoise_main - The osnoise detection kernel thread * * Calls run_osnoise() function to measure the osnoise for the configured runtime, @@ -1553,12 +1688,35 @@ static void osnoise_sleep(void) */ static int osnoise_main(void *data) { + unsigned long flags; + + /* + * This thread was created pinned to the CPU using PF_NO_SETAFFINITY. + * The problem is that cgroup does not allow PF_NO_SETAFFINITY thread. + * + * To work around this limitation, disable migration and remove the + * flag. + */ + migrate_disable(); + raw_spin_lock_irqsave(¤t->pi_lock, flags); + current->flags &= ~(PF_NO_SETAFFINITY); + raw_spin_unlock_irqrestore(¤t->pi_lock, flags); while (!kthread_should_stop()) { + if (osnoise_migration_pending()) + break; + + /* skip a period if tracing is off on all instances */ + if (!osnoise_has_tracing_on()) { + osnoise_sleep(true); + continue; + } + run_osnoise(); - osnoise_sleep(); + osnoise_sleep(false); } + migrate_enable(); return 0; } @@ -1706,6 +1864,7 @@ static int timerlat_main(void *data) struct timerlat_variables *tlat = this_cpu_tmr_var(); struct timerlat_sample s; struct sched_param sp; + unsigned long flags; u64 now, diff; /* @@ -1714,6 +1873,18 @@ static int timerlat_main(void *data) sp.sched_priority = DEFAULT_TIMERLAT_PRIO; sched_setscheduler_nocheck(current, SCHED_FIFO, &sp); + /* + * This thread was created pinned to the CPU using PF_NO_SETAFFINITY. + * The problem is that cgroup does not allow PF_NO_SETAFFINITY thread. + * + * To work around this limitation, disable migration and remove the + * flag. + */ + migrate_disable(); + raw_spin_lock_irqsave(¤t->pi_lock, flags); + current->flags &= ~(PF_NO_SETAFFINITY); + raw_spin_unlock_irqrestore(¤t->pi_lock, flags); + tlat->count = 0; tlat->tracing_thread = false; @@ -1731,6 +1902,7 @@ static int timerlat_main(void *data) osn_var->sampling = 1; while (!kthread_should_stop()) { + now = ktime_to_ns(hrtimer_cb_get_time(&tlat->timer)); diff = now - tlat->abs_period; @@ -1749,10 +1921,14 @@ static int timerlat_main(void *data) if (time_to_us(diff) >= osnoise_data.stop_tracing_total) osnoise_stop_tracing(); + if (osnoise_migration_pending()) + break; + wait_next_period(tlat); } hrtimer_cancel(&tlat->timer); + migrate_enable(); return 0; } #else /* CONFIG_TIMERLAT_TRACER */ @@ -1771,10 +1947,24 @@ static void stop_kthread(unsigned int cpu) kthread = per_cpu(per_cpu_osnoise_var, cpu).kthread; if (kthread) { - kthread_stop(kthread); + if (test_bit(OSN_WORKLOAD, &osnoise_options)) { + kthread_stop(kthread); + } else { + /* + * This is a user thread waiting on the timerlat_fd. We need + * to close all users, and the best way to guarantee this is + * by killing the thread. NOTE: this is a purpose specific file. + */ + kill_pid(kthread->thread_pid, SIGKILL, 1); + put_task_struct(kthread); + } per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL; } else { + /* if no workload, just return */ if (!test_bit(OSN_WORKLOAD, &osnoise_options)) { + /* + * This is set in the osnoise tracer case. + */ per_cpu(per_cpu_osnoise_var, cpu).sampling = false; barrier(); return; @@ -1819,7 +2009,6 @@ static int start_kthread(unsigned int cpu) barrier(); return 0; } - snprintf(comm, 24, "osnoise/%d", cpu); } @@ -1848,6 +2037,11 @@ static int start_per_cpu_kthreads(void) int retval = 0; int cpu; + if (!test_bit(OSN_WORKLOAD, &osnoise_options)) { + if (timerlat_enabled()) + return 0; + } + cpus_read_lock(); /* * Run only on online CPUs in which osnoise is allowed to run. @@ -2188,6 +2382,223 @@ err_free: return err; } +#ifdef CONFIG_TIMERLAT_TRACER +static int timerlat_fd_open(struct inode *inode, struct file *file) +{ + struct osnoise_variables *osn_var; + struct timerlat_variables *tlat; + long cpu = (long) inode->i_cdev; + + mutex_lock(&interface_lock); + + /* + * This file is accessible only if timerlat is enabled, and + * NO_OSNOISE_WORKLOAD is set. + */ + if (!timerlat_enabled() || test_bit(OSN_WORKLOAD, &osnoise_options)) { + mutex_unlock(&interface_lock); + return -EINVAL; + } + + migrate_disable(); + + osn_var = this_cpu_osn_var(); + + /* + * The osn_var->pid holds the single access to this file. + */ + if (osn_var->pid) { + mutex_unlock(&interface_lock); + migrate_enable(); + return -EBUSY; + } + + /* + * timerlat tracer is a per-cpu tracer. Check if the user-space too + * is pinned to a single CPU. The tracer laters monitor if the task + * migrates and then disables tracer if it does. However, it is + * worth doing this basic acceptance test to avoid obviusly wrong + * setup. + */ + if (current->nr_cpus_allowed > 1 || cpu != smp_processor_id()) { + mutex_unlock(&interface_lock); + migrate_enable(); + return -EPERM; + } + + /* + * From now on, it is good to go. + */ + file->private_data = inode->i_cdev; + + get_task_struct(current); + + osn_var->kthread = current; + osn_var->pid = current->pid; + + /* + * Setup is done. + */ + mutex_unlock(&interface_lock); + + tlat = this_cpu_tmr_var(); + tlat->count = 0; + + migrate_enable(); + return 0; +}; + +/* + * timerlat_fd_read - Read function for "timerlat_fd" file + * @file: The active open file structure + * @ubuf: The userspace provided buffer to read value into + * @cnt: The maximum number of bytes to read + * @ppos: The current "file" position + * + * Prints 1 on timerlat, the number of interferences on osnoise, -1 on error. + */ +static ssize_t +timerlat_fd_read(struct file *file, char __user *ubuf, size_t count, + loff_t *ppos) +{ + long cpu = (long) file->private_data; + struct osnoise_variables *osn_var; + struct timerlat_variables *tlat; + struct timerlat_sample s; + s64 diff; + u64 now; + + migrate_disable(); + + tlat = this_cpu_tmr_var(); + + /* + * While in user-space, the thread is migratable. There is nothing + * we can do about it. + * So, if the thread is running on another CPU, stop the machinery. + */ + if (cpu == smp_processor_id()) { + if (tlat->uthread_migrate) { + migrate_enable(); + return -EINVAL; + } + } else { + per_cpu_ptr(&per_cpu_timerlat_var, cpu)->uthread_migrate = 1; + osnoise_taint("timerlat user thread migrate\n"); + osnoise_stop_tracing(); + migrate_enable(); + return -EINVAL; + } + + osn_var = this_cpu_osn_var(); + + /* + * The timerlat in user-space runs in a different order: + * the read() starts from the execution of the previous occurrence, + * sleeping for the next occurrence. + * + * So, skip if we are entering on read() before the first wakeup + * from timerlat IRQ: + */ + if (likely(osn_var->sampling)) { + now = ktime_to_ns(hrtimer_cb_get_time(&tlat->timer)); + diff = now - tlat->abs_period; + + /* + * it was not a timer firing, but some other signal? + */ + if (diff < 0) + goto out; + + s.seqnum = tlat->count; + s.timer_latency = diff; + s.context = THREAD_URET; + + trace_timerlat_sample(&s); + + notify_new_max_latency(diff); + + tlat->tracing_thread = false; + if (osnoise_data.stop_tracing_total) + if (time_to_us(diff) >= osnoise_data.stop_tracing_total) + osnoise_stop_tracing(); + } else { + tlat->tracing_thread = false; + tlat->kthread = current; + + hrtimer_init(&tlat->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD); + tlat->timer.function = timerlat_irq; + + /* Annotate now to drift new period */ + tlat->abs_period = hrtimer_cb_get_time(&tlat->timer); + + osn_var->sampling = 1; + } + + /* wait for the next period */ + wait_next_period(tlat); + + /* This is the wakeup from this cycle */ + now = ktime_to_ns(hrtimer_cb_get_time(&tlat->timer)); + diff = now - tlat->abs_period; + + /* + * it was not a timer firing, but some other signal? + */ + if (diff < 0) + goto out; + + s.seqnum = tlat->count; + s.timer_latency = diff; + s.context = THREAD_CONTEXT; + + trace_timerlat_sample(&s); + + if (osnoise_data.stop_tracing_total) { + if (time_to_us(diff) >= osnoise_data.stop_tracing_total) { + timerlat_dump_stack(time_to_us(diff)); + notify_new_max_latency(diff); + osnoise_stop_tracing(); + } + } + +out: + migrate_enable(); + return 0; +} + +static int timerlat_fd_release(struct inode *inode, struct file *file) +{ + struct osnoise_variables *osn_var; + struct timerlat_variables *tlat_var; + long cpu = (long) file->private_data; + + migrate_disable(); + mutex_lock(&interface_lock); + + osn_var = per_cpu_ptr(&per_cpu_osnoise_var, cpu); + tlat_var = per_cpu_ptr(&per_cpu_timerlat_var, cpu); + + hrtimer_cancel(&tlat_var->timer); + memset(tlat_var, 0, sizeof(*tlat_var)); + + osn_var->sampling = 0; + osn_var->pid = 0; + + /* + * We are leaving, not being stopped... see stop_kthread(); + */ + if (osn_var->kthread) { + put_task_struct(osn_var->kthread); + osn_var->kthread = NULL; + } + + mutex_unlock(&interface_lock); + migrate_enable(); + return 0; +} +#endif + /* * osnoise/runtime_us: cannot be greater than the period. */ @@ -2251,6 +2662,13 @@ static struct trace_min_max_param timerlat_period = { .max = &timerlat_max_period, .min = &timerlat_min_period, }; + +static const struct file_operations timerlat_fd_fops = { + .open = timerlat_fd_open, + .read = timerlat_fd_read, + .release = timerlat_fd_release, + .llseek = generic_file_llseek, +}; #endif static const struct file_operations cpus_fops = { @@ -2288,18 +2706,63 @@ static int init_timerlat_stack_tracefs(struct dentry *top_dir) } #endif /* CONFIG_STACKTRACE */ +static int osnoise_create_cpu_timerlat_fd(struct dentry *top_dir) +{ + struct dentry *timerlat_fd; + struct dentry *per_cpu; + struct dentry *cpu_dir; + char cpu_str[30]; /* see trace.c: tracing_init_tracefs_percpu() */ + long cpu; + + /* + * Why not using tracing instance per_cpu/ dir? + * + * Because osnoise/timerlat have a single workload, having + * multiple files like these are wast of memory. + */ + per_cpu = tracefs_create_dir("per_cpu", top_dir); + if (!per_cpu) + return -ENOMEM; + + for_each_possible_cpu(cpu) { + snprintf(cpu_str, 30, "cpu%ld", cpu); + cpu_dir = tracefs_create_dir(cpu_str, per_cpu); + if (!cpu_dir) + goto out_clean; + + timerlat_fd = trace_create_file("timerlat_fd", TRACE_MODE_READ, + cpu_dir, NULL, &timerlat_fd_fops); + if (!timerlat_fd) + goto out_clean; + + /* Record the CPU */ + d_inode(timerlat_fd)->i_cdev = (void *)(cpu); + } + + return 0; + +out_clean: + tracefs_remove(per_cpu); + return -ENOMEM; +} + /* * init_timerlat_tracefs - A function to initialize the timerlat interface files */ static int init_timerlat_tracefs(struct dentry *top_dir) { struct dentry *tmp; + int retval; tmp = tracefs_create_file("timerlat_period_us", TRACE_MODE_WRITE, top_dir, &timerlat_period, &trace_min_max_fops); if (!tmp) return -ENOMEM; + retval = osnoise_create_cpu_timerlat_fd(top_dir); + if (retval) + return retval; + return init_timerlat_stack_tracefs(top_dir); } #else /* CONFIG_TIMERLAT_TRACER */ diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index 1e33f367783e..db575094c498 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -1446,6 +1446,8 @@ static struct trace_event trace_osnoise_event = { }; /* TRACE_TIMERLAT */ + +static char *timerlat_lat_context[] = {"irq", "thread", "user-ret"}; static enum print_line_t trace_timerlat_print(struct trace_iterator *iter, int flags, struct trace_event *event) @@ -1458,7 +1460,7 @@ trace_timerlat_print(struct trace_iterator *iter, int flags, trace_seq_printf(s, "#%-5u context %6s timer_latency %9llu ns\n", field->seqnum, - field->context ? "thread" : "irq", + timerlat_lat_context[field->context], field->timer_latency); return trace_handle_return(s); |