diff options
| -rw-r--r-- | include/linux/ftrace.h | 1 | ||||
| -rw-r--r-- | kernel/trace/ftrace.c | 33 | ||||
| -rw-r--r-- | kernel/trace/trace.h | 22 | ||||
| -rw-r--r-- | kernel/trace/trace_functions_graph.c | 56 |
4 files changed, 109 insertions, 3 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 9f15c0064c50..ec85d48619e1 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -721,6 +721,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth, extern char __irqentry_text_start[]; extern char __irqentry_text_end[]; +#define FTRACE_NOTRACE_DEPTH 65536 #define FTRACE_RETFUNC_DEPTH 50 #define FTRACE_RETSTACK_ALLOC_SIZE 32 extern int register_ftrace_graph(trace_func_graph_ret_t retfunc, diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 26a229ab0c19..44e826a79665 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3776,7 +3776,9 @@ static const struct file_operations ftrace_notrace_fops = { static DEFINE_MUTEX(graph_lock); int ftrace_graph_count; +int ftrace_graph_notrace_count; unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly; +unsigned long ftrace_graph_notrace_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly; struct ftrace_graph_data { unsigned long *table; @@ -3891,6 +3893,26 @@ ftrace_graph_open(struct inode *inode, struct file *file) } static int +ftrace_graph_notrace_open(struct inode *inode, struct file *file) +{ + struct ftrace_graph_data *fgd; + + if (unlikely(ftrace_disabled)) + return -ENODEV; + + fgd = kmalloc(sizeof(*fgd), GFP_KERNEL); + if (fgd == NULL) + return -ENOMEM; + + fgd->table = ftrace_graph_notrace_funcs; + fgd->size = FTRACE_GRAPH_MAX_FUNCS; + fgd->count = &ftrace_graph_notrace_count; + fgd->seq_ops = &ftrace_graph_seq_ops; + + return __ftrace_graph_open(inode, file, fgd); +} + +static int ftrace_graph_release(struct inode *inode, struct file *file) { if (file->f_mode & FMODE_READ) { @@ -4011,6 +4033,14 @@ static const struct file_operations ftrace_graph_fops = { .llseek = ftrace_filter_lseek, .release = ftrace_graph_release, }; + +static const struct file_operations ftrace_graph_notrace_fops = { + .open = ftrace_graph_notrace_open, + .read = seq_read, + .write = ftrace_graph_write, + .llseek = ftrace_filter_lseek, + .release = ftrace_graph_release, +}; #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer) @@ -4032,6 +4062,9 @@ static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer) trace_create_file("set_graph_function", 0444, d_tracer, NULL, &ftrace_graph_fops); + trace_create_file("set_graph_notrace", 0444, d_tracer, + NULL, + &ftrace_graph_notrace_fops); #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ return 0; diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 40211cef2796..d1cf5159bec0 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -732,6 +732,8 @@ extern void __trace_graph_return(struct trace_array *tr, #define FTRACE_GRAPH_MAX_FUNCS 32 extern int ftrace_graph_count; extern unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS]; +extern int ftrace_graph_notrace_count; +extern unsigned long ftrace_graph_notrace_funcs[FTRACE_GRAPH_MAX_FUNCS]; static inline int ftrace_graph_addr(unsigned long addr) { @@ -757,11 +759,31 @@ static inline int ftrace_graph_addr(unsigned long addr) return 0; } + +static inline int ftrace_graph_notrace_addr(unsigned long addr) +{ + int i; + + if (!ftrace_graph_notrace_count) + return 0; + + for (i = 0; i < ftrace_graph_notrace_count; i++) { + if (addr == ftrace_graph_notrace_funcs[i]) + return 1; + } + + return 0; +} #else static inline int ftrace_graph_addr(unsigned long addr) { return 1; } + +static inline int ftrace_graph_notrace_addr(unsigned long addr) +{ + return 0; +} #endif /* CONFIG_DYNAMIC_FTRACE */ #else /* CONFIG_FUNCTION_GRAPH_TRACER */ static inline enum print_line_t diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index b5c09242683d..e08c030b8f38 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -114,16 +114,37 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth, return -EBUSY; } + /* + * The curr_ret_stack is an index to ftrace return stack of + * current task. Its value should be in [0, FTRACE_RETFUNC_ + * DEPTH) when the function graph tracer is used. To support + * filtering out specific functions, it makes the index + * negative by subtracting huge value (FTRACE_NOTRACE_DEPTH) + * so when it sees a negative index the ftrace will ignore + * the record. And the index gets recovered when returning + * from the filtered function by adding the FTRACE_NOTRACE_ + * DEPTH and then it'll continue to record functions normally. + * + * The curr_ret_stack is initialized to -1 and get increased + * in this function. So it can be less than -1 only if it was + * filtered out via ftrace_graph_notrace_addr() which can be + * set from set_graph_notrace file in debugfs by user. + */ + if (current->curr_ret_stack < -1) + return -EBUSY; + calltime = trace_clock_local(); index = ++current->curr_ret_stack; + if (ftrace_graph_notrace_addr(func)) + current->curr_ret_stack -= FTRACE_NOTRACE_DEPTH; barrier(); current->ret_stack[index].ret = ret; current->ret_stack[index].func = func; current->ret_stack[index].calltime = calltime; current->ret_stack[index].subtime = 0; current->ret_stack[index].fp = frame_pointer; - *depth = index; + *depth = current->curr_ret_stack; return 0; } @@ -137,7 +158,17 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret, index = current->curr_ret_stack; - if (unlikely(index < 0)) { + /* + * A negative index here means that it's just returned from a + * notrace'd function. Recover index to get an original + * return address. See ftrace_push_return_trace(). + * + * TODO: Need to check whether the stack gets corrupted. + */ + if (index < 0) + index += FTRACE_NOTRACE_DEPTH; + + if (unlikely(index < 0 || index >= FTRACE_RETFUNC_DEPTH)) { ftrace_graph_stop(); WARN_ON(1); /* Might as well panic, otherwise we have no where to go */ @@ -193,6 +224,15 @@ unsigned long ftrace_return_to_handler(unsigned long frame_pointer) trace.rettime = trace_clock_local(); barrier(); current->curr_ret_stack--; + /* + * The curr_ret_stack can be less than -1 only if it was + * filtered out and it's about to return from the function. + * Recover the index and continue to trace normal functions. + */ + if (current->curr_ret_stack < -1) { + current->curr_ret_stack += FTRACE_NOTRACE_DEPTH; + return ret; + } /* * The trace should run after decrementing the ret counter @@ -259,10 +299,20 @@ int trace_graph_entry(struct ftrace_graph_ent *trace) /* trace it when it is-nested-in or is a function enabled. */ if ((!(trace->depth || ftrace_graph_addr(trace->func)) || - ftrace_graph_ignore_irqs()) || + ftrace_graph_ignore_irqs()) || (trace->depth < 0) || (max_depth && trace->depth >= max_depth)) return 0; + /* + * Do not trace a function if it's filtered by set_graph_notrace. + * Make the index of ret stack negative to indicate that it should + * ignore further functions. But it needs its own ret stack entry + * to recover the original index in order to continue tracing after + * returning from the function. + */ + if (ftrace_graph_notrace_addr(trace->func)) + return 1; + local_irq_save(flags); cpu = raw_smp_processor_id(); data = per_cpu_ptr(tr->trace_buffer.data, cpu); |