diff options
| -rw-r--r-- | include/linux/kernel.h | 13 | ||||
| -rw-r--r-- | kernel/trace/trace.c | 184 | ||||
| -rw-r--r-- | kernel/trace/trace.h | 2 | ||||
| -rw-r--r-- | kernel/trace/trace_printk.c | 4 |
4 files changed, 148 insertions, 55 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 645231c373c8..c0d34420a913 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -480,15 +480,16 @@ do { \ #define trace_printk(fmt, args...) \ do { \ + static const char *trace_printk_fmt \ + __attribute__((section("__trace_printk_fmt"))) = \ + __builtin_constant_p(fmt) ? fmt : NULL; \ + \ __trace_printk_check_format(fmt, ##args); \ - if (__builtin_constant_p(fmt)) { \ - static const char *trace_printk_fmt \ - __attribute__((section("__trace_printk_fmt"))) = \ - __builtin_constant_p(fmt) ? fmt : NULL; \ \ + if (__builtin_constant_p(fmt)) \ __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args); \ - } else \ - __trace_printk(_THIS_IP_, fmt, ##args); \ + else \ + __trace_printk(_THIS_IP_, fmt, ##args); \ } while (0) extern __printf(2, 3) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index ed7b5d1e12f4..1ab8e35d069b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1498,25 +1498,119 @@ static void __trace_userstack(struct trace_array *tr, unsigned long flags) #endif /* CONFIG_STACKTRACE */ +/* created for use with alloc_percpu */ +struct trace_buffer_struct { + char buffer[TRACE_BUF_SIZE]; +}; + +static struct trace_buffer_struct *trace_percpu_buffer; +static struct trace_buffer_struct *trace_percpu_sirq_buffer; +static struct trace_buffer_struct *trace_percpu_irq_buffer; +static struct trace_buffer_struct *trace_percpu_nmi_buffer; + +/* + * The buffer used is dependent on the context. There is a per cpu + * buffer for normal context, softirq contex, hard irq context and + * for NMI context. Thise allows for lockless recording. + * + * Note, if the buffers failed to be allocated, then this returns NULL + */ +static char *get_trace_buf(void) +{ + struct trace_buffer_struct *percpu_buffer; + struct trace_buffer_struct *buffer; + + /* + * If we have allocated per cpu buffers, then we do not + * need to do any locking. + */ + if (in_nmi()) + percpu_buffer = trace_percpu_nmi_buffer; + else if (in_irq()) + percpu_buffer = trace_percpu_irq_buffer; + else if (in_softirq()) + percpu_buffer = trace_percpu_sirq_buffer; + else + percpu_buffer = trace_percpu_buffer; + + if (!percpu_buffer) + return NULL; + + buffer = per_cpu_ptr(percpu_buffer, smp_processor_id()); + + return buffer->buffer; +} + +static int alloc_percpu_trace_buffer(void) +{ + struct trace_buffer_struct *buffers; + struct trace_buffer_struct *sirq_buffers; + struct trace_buffer_struct *irq_buffers; + struct trace_buffer_struct *nmi_buffers; + + buffers = alloc_percpu(struct trace_buffer_struct); + if (!buffers) + goto err_warn; + + sirq_buffers = alloc_percpu(struct trace_buffer_struct); + if (!sirq_buffers) + goto err_sirq; + + irq_buffers = alloc_percpu(struct trace_buffer_struct); + if (!irq_buffers) + goto err_irq; + + nmi_buffers = alloc_percpu(struct trace_buffer_struct); + if (!nmi_buffers) + goto err_nmi; + + trace_percpu_buffer = buffers; + trace_percpu_sirq_buffer = sirq_buffers; + trace_percpu_irq_buffer = irq_buffers; + trace_percpu_nmi_buffer = nmi_buffers; + + return 0; + + err_nmi: + free_percpu(irq_buffers); + err_irq: + free_percpu(sirq_buffers); + err_sirq: + free_percpu(buffers); + err_warn: + WARN(1, "Could not allocate percpu trace_printk buffer"); + return -ENOMEM; +} + +void trace_printk_init_buffers(void) +{ + static int buffers_allocated; + + if (buffers_allocated) + return; + + if (alloc_percpu_trace_buffer()) + return; + + pr_info("ftrace: Allocated trace_printk buffers\n"); + + buffers_allocated = 1; +} + /** * trace_vbprintk - write binary msg to tracing buffer * */ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args) { - static arch_spinlock_t trace_buf_lock = - (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; - static u32 trace_buf[TRACE_BUF_SIZE]; - struct ftrace_event_call *call = &event_bprint; struct ring_buffer_event *event; struct ring_buffer *buffer; struct trace_array *tr = &global_trace; - struct trace_array_cpu *data; struct bprint_entry *entry; unsigned long flags; - int disable; - int cpu, len = 0, size, pc; + char *tbuffer; + int len = 0, size, pc; if (unlikely(tracing_selftest_running || tracing_disabled)) return 0; @@ -1526,43 +1620,36 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args) pc = preempt_count(); preempt_disable_notrace(); - cpu = raw_smp_processor_id(); - data = tr->data[cpu]; - disable = atomic_inc_return(&data->disabled); - if (unlikely(disable != 1)) + tbuffer = get_trace_buf(); + if (!tbuffer) { + len = 0; goto out; + } - /* Lockdep uses trace_printk for lock tracing */ - local_irq_save(flags); - arch_spin_lock(&trace_buf_lock); - len = vbin_printf(trace_buf, TRACE_BUF_SIZE, fmt, args); + len = vbin_printf((u32 *)tbuffer, TRACE_BUF_SIZE/sizeof(int), fmt, args); - if (len > TRACE_BUF_SIZE || len < 0) - goto out_unlock; + if (len > TRACE_BUF_SIZE/sizeof(int) || len < 0) + goto out; + local_save_flags(flags); size = sizeof(*entry) + sizeof(u32) * len; buffer = tr->buffer; event = trace_buffer_lock_reserve(buffer, TRACE_BPRINT, size, flags, pc); if (!event) - goto out_unlock; + goto out; entry = ring_buffer_event_data(event); entry->ip = ip; entry->fmt = fmt; - memcpy(entry->buf, trace_buf, sizeof(u32) * len); + memcpy(entry->buf, tbuffer, sizeof(u32) * len); if (!filter_check_discard(call, entry, buffer, event)) { ring_buffer_unlock_commit(buffer, event); ftrace_trace_stack(buffer, flags, 6, pc); } -out_unlock: - arch_spin_unlock(&trace_buf_lock); - local_irq_restore(flags); - out: - atomic_dec_return(&data->disabled); preempt_enable_notrace(); unpause_graph_tracing(); @@ -1588,58 +1675,53 @@ int trace_array_printk(struct trace_array *tr, int trace_array_vprintk(struct trace_array *tr, unsigned long ip, const char *fmt, va_list args) { - static arch_spinlock_t trace_buf_lock = __ARCH_SPIN_LOCK_UNLOCKED; - static char trace_buf[TRACE_BUF_SIZE]; - struct ftrace_event_call *call = &event_print; struct ring_buffer_event *event; struct ring_buffer *buffer; - struct trace_array_cpu *data; - int cpu, len = 0, size, pc; + int len = 0, size, pc; struct print_entry *entry; - unsigned long irq_flags; - int disable; + unsigned long flags; + char *tbuffer; if (tracing_disabled || tracing_selftest_running) return 0; + /* Don't pollute graph traces with trace_vprintk internals */ + pause_graph_tracing(); + pc = preempt_count(); preempt_disable_notrace(); - cpu = raw_smp_processor_id(); - data = tr->data[cpu]; - disable = atomic_inc_return(&data->disabled); - if (unlikely(disable != 1)) + + tbuffer = get_trace_buf(); + if (!tbuffer) { + len = 0; goto out; + } - pause_graph_tracing(); - raw_local_irq_save(irq_flags); - arch_spin_lock(&trace_buf_lock); - len = vsnprintf(trace_buf, TRACE_BUF_SIZE, fmt, args); + len = vsnprintf(tbuffer, TRACE_BUF_SIZE, fmt, args); + if (len > TRACE_BUF_SIZE) + goto out; + local_save_flags(flags); size = sizeof(*entry) + len + 1; buffer = tr->buffer; event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, size, - irq_flags, pc); + flags, pc); if (!event) - goto out_unlock; + goto out; entry = ring_buffer_event_data(event); entry->ip = ip; - memcpy(&entry->buf, trace_buf, len); + memcpy(&entry->buf, tbuffer, len); entry->buf[len] = '\0'; if (!filter_check_discard(call, entry, buffer, event)) { ring_buffer_unlock_commit(buffer, event); - ftrace_trace_stack(buffer, irq_flags, 6, pc); + ftrace_trace_stack(buffer, flags, 6, pc); } - - out_unlock: - arch_spin_unlock(&trace_buf_lock); - raw_local_irq_restore(irq_flags); - unpause_graph_tracing(); out: - atomic_dec_return(&data->disabled); preempt_enable_notrace(); + unpause_graph_tracing(); return len; } @@ -4955,6 +5037,10 @@ __init static int tracer_alloc_buffers(void) if (!alloc_cpumask_var(&tracing_cpumask, GFP_KERNEL)) goto out_free_buffer_mask; + /* Only allocate trace_printk buffers if a trace_printk exists */ + if (__stop___trace_bprintk_fmt != __start___trace_bprintk_fmt) + trace_printk_init_buffers(); + /* To save memory, keep the ring buffer size to its minimum */ if (ring_buffer_expanded) ring_buf_size = trace_buf_size; diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 95059f091a24..f9d85504f04b 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -826,6 +826,8 @@ extern struct list_head ftrace_events; extern const char *__start___trace_bprintk_fmt[]; extern const char *__stop___trace_bprintk_fmt[]; +void trace_printk_init_buffers(void); + #undef FTRACE_ENTRY #define FTRACE_ENTRY(call, struct_name, id, tstruct, print, filter) \ extern struct ftrace_event_call \ diff --git a/kernel/trace/trace_printk.c b/kernel/trace/trace_printk.c index 6fd4ffd042f9..a9077c1b4ad3 100644 --- a/kernel/trace/trace_printk.c +++ b/kernel/trace/trace_printk.c @@ -51,6 +51,10 @@ void hold_module_trace_bprintk_format(const char **start, const char **end) const char **iter; char *fmt; + /* allocate the trace_printk per cpu buffers */ + if (start != end) + trace_printk_init_buffers(); + mutex_lock(&btrace_mutex); for (iter = start; iter < end; iter++) { struct trace_bprintk_fmt *tb_fmt = lookup_format(*iter); |