diff options
| -rw-r--r-- | include/linux/ftrace.h | 66 | ||||
| -rw-r--r-- | kernel/trace/ftrace.c | 111 | ||||
| -rw-r--r-- | kernel/trace/trace.h | 2 |
3 files changed, 172 insertions, 7 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index f33fb3b041c6..64a309d2fbd6 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -31,16 +31,33 @@ ftrace_enable_sysctl(struct ctl_table *table, int write, typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip); +/* + * FTRACE_OPS_FL_* bits denote the state of ftrace_ops struct and are + * set in the flags member. + * + * ENABLED - set/unset when ftrace_ops is registered/unregistered + * GLOBAL - set manualy by ftrace_ops user to denote the ftrace_ops + * is part of the global tracers sharing the same filter + * via set_ftrace_* debugfs files. + * DYNAMIC - set when ftrace_ops is registered to denote dynamically + * allocated ftrace_ops which need special care + * CONTROL - set manualy by ftrace_ops user to denote the ftrace_ops + * could be controled by following calls: + * ftrace_function_local_enable + * ftrace_function_local_disable + */ enum { FTRACE_OPS_FL_ENABLED = 1 << 0, FTRACE_OPS_FL_GLOBAL = 1 << 1, FTRACE_OPS_FL_DYNAMIC = 1 << 2, + FTRACE_OPS_FL_CONTROL = 1 << 3, }; struct ftrace_ops { ftrace_func_t func; struct ftrace_ops *next; unsigned long flags; + int __percpu *disabled; #ifdef CONFIG_DYNAMIC_FTRACE struct ftrace_hash *notrace_hash; struct ftrace_hash *filter_hash; @@ -97,6 +114,55 @@ int register_ftrace_function(struct ftrace_ops *ops); int unregister_ftrace_function(struct ftrace_ops *ops); void clear_ftrace_function(void); +/** + * ftrace_function_local_enable - enable controlled ftrace_ops on current cpu + * + * This function enables tracing on current cpu by decreasing + * the per cpu control variable. + * It must be called with preemption disabled and only on ftrace_ops + * registered with FTRACE_OPS_FL_CONTROL. If called without preemption + * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled. + */ +static inline void ftrace_function_local_enable(struct ftrace_ops *ops) +{ + if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL))) + return; + + (*this_cpu_ptr(ops->disabled))--; +} + +/** + * ftrace_function_local_disable - enable controlled ftrace_ops on current cpu + * + * This function enables tracing on current cpu by decreasing + * the per cpu control variable. + * It must be called with preemption disabled and only on ftrace_ops + * registered with FTRACE_OPS_FL_CONTROL. If called without preemption + * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled. + */ +static inline void ftrace_function_local_disable(struct ftrace_ops *ops) +{ + if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL))) + return; + + (*this_cpu_ptr(ops->disabled))++; +} + +/** + * ftrace_function_local_disabled - returns ftrace_ops disabled value + * on current cpu + * + * This function returns value of ftrace_ops::disabled on current cpu. + * It must be called with preemption disabled and only on ftrace_ops + * registered with FTRACE_OPS_FL_CONTROL. If called without preemption + * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled. + */ +static inline int ftrace_function_local_disabled(struct ftrace_ops *ops) +{ + WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL)); + return *this_cpu_ptr(ops->disabled); +} + extern void ftrace_stub(unsigned long a0, unsigned long a1); #else /* !CONFIG_FUNCTION_TRACER */ diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index d1499e910fe8..f615f974d90e 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -62,6 +62,8 @@ #define FTRACE_HASH_DEFAULT_BITS 10 #define FTRACE_HASH_MAX_BITS 12 +#define FL_GLOBAL_CONTROL_MASK (FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_CONTROL) + /* ftrace_enabled is a method to turn ftrace on or off */ int ftrace_enabled __read_mostly; static int last_ftrace_enabled; @@ -89,12 +91,14 @@ static struct ftrace_ops ftrace_list_end __read_mostly = { }; static struct ftrace_ops *ftrace_global_list __read_mostly = &ftrace_list_end; +static struct ftrace_ops *ftrace_control_list __read_mostly = &ftrace_list_end; static struct ftrace_ops *ftrace_ops_list __read_mostly = &ftrace_list_end; ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub; static ftrace_func_t __ftrace_trace_function_delay __read_mostly = ftrace_stub; ftrace_func_t __ftrace_trace_function __read_mostly = ftrace_stub; ftrace_func_t ftrace_pid_function __read_mostly = ftrace_stub; static struct ftrace_ops global_ops; +static struct ftrace_ops control_ops; static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip); @@ -168,6 +172,32 @@ static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip) } #endif +static void control_ops_disable_all(struct ftrace_ops *ops) +{ + int cpu; + + for_each_possible_cpu(cpu) + *per_cpu_ptr(ops->disabled, cpu) = 1; +} + +static int control_ops_alloc(struct ftrace_ops *ops) +{ + int __percpu *disabled; + + disabled = alloc_percpu(int); + if (!disabled) + return -ENOMEM; + + ops->disabled = disabled; + control_ops_disable_all(ops); + return 0; +} + +static void control_ops_free(struct ftrace_ops *ops) +{ + free_percpu(ops->disabled); +} + static void update_global_ops(void) { ftrace_func_t func; @@ -259,6 +289,26 @@ static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops) return 0; } +static void add_ftrace_list_ops(struct ftrace_ops **list, + struct ftrace_ops *main_ops, + struct ftrace_ops *ops) +{ + int first = *list == &ftrace_list_end; + add_ftrace_ops(list, ops); + if (first) + add_ftrace_ops(&ftrace_ops_list, main_ops); +} + +static int remove_ftrace_list_ops(struct ftrace_ops **list, + struct ftrace_ops *main_ops, + struct ftrace_ops *ops) +{ + int ret = remove_ftrace_ops(list, ops); + if (!ret && *list == &ftrace_list_end) + ret = remove_ftrace_ops(&ftrace_ops_list, main_ops); + return ret; +} + static int __register_ftrace_function(struct ftrace_ops *ops) { if (ftrace_disabled) @@ -270,15 +320,20 @@ static int __register_ftrace_function(struct ftrace_ops *ops) if (WARN_ON(ops->flags & FTRACE_OPS_FL_ENABLED)) return -EBUSY; + /* We don't support both control and global flags set. */ + if ((ops->flags & FL_GLOBAL_CONTROL_MASK) == FL_GLOBAL_CONTROL_MASK) + return -EINVAL; + if (!core_kernel_data((unsigned long)ops)) ops->flags |= FTRACE_OPS_FL_DYNAMIC; if (ops->flags & FTRACE_OPS_FL_GLOBAL) { - int first = ftrace_global_list == &ftrace_list_end; - add_ftrace_ops(&ftrace_global_list, ops); + add_ftrace_list_ops(&ftrace_global_list, &global_ops, ops); ops->flags |= FTRACE_OPS_FL_ENABLED; - if (first) - add_ftrace_ops(&ftrace_ops_list, &global_ops); + } else if (ops->flags & FTRACE_OPS_FL_CONTROL) { + if (control_ops_alloc(ops)) + return -ENOMEM; + add_ftrace_list_ops(&ftrace_control_list, &control_ops, ops); } else add_ftrace_ops(&ftrace_ops_list, ops); @@ -302,11 +357,23 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops) return -EINVAL; if (ops->flags & FTRACE_OPS_FL_GLOBAL) { - ret = remove_ftrace_ops(&ftrace_global_list, ops); - if (!ret && ftrace_global_list == &ftrace_list_end) - ret = remove_ftrace_ops(&ftrace_ops_list, &global_ops); + ret = remove_ftrace_list_ops(&ftrace_global_list, + &global_ops, ops); if (!ret) ops->flags &= ~FTRACE_OPS_FL_ENABLED; + } else if (ops->flags & FTRACE_OPS_FL_CONTROL) { + ret = remove_ftrace_list_ops(&ftrace_control_list, + &control_ops, ops); + if (!ret) { + /* + * The ftrace_ops is now removed from the list, + * so there'll be no new users. We must ensure + * all current users are done before we free + * the control data. + */ + synchronize_sched(); + control_ops_free(ops); + } } else ret = remove_ftrace_ops(&ftrace_ops_list, ops); @@ -3874,6 +3941,36 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip) #endif /* CONFIG_DYNAMIC_FTRACE */ static void +ftrace_ops_control_func(unsigned long ip, unsigned long parent_ip) +{ + struct ftrace_ops *op; + + if (unlikely(trace_recursion_test(TRACE_CONTROL_BIT))) + return; + + /* + * Some of the ops may be dynamically allocated, + * they must be freed after a synchronize_sched(). + */ + preempt_disable_notrace(); + trace_recursion_set(TRACE_CONTROL_BIT); + op = rcu_dereference_raw(ftrace_control_list); + while (op != &ftrace_list_end) { + if (!ftrace_function_local_disabled(op) && + ftrace_ops_test(op, ip)) + op->func(ip, parent_ip); + + op = rcu_dereference_raw(op->next); + }; + trace_recursion_clear(TRACE_CONTROL_BIT); + preempt_enable_notrace(); +} + +static struct ftrace_ops control_ops = { + .func = ftrace_ops_control_func, +}; + +static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip) { struct ftrace_ops *op; diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index b93ecbadad6d..55c6ea00f28a 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -288,6 +288,8 @@ struct tracer { /* for function tracing recursion */ #define TRACE_INTERNAL_BIT (1<<11) #define TRACE_GLOBAL_BIT (1<<12) +#define TRACE_CONTROL_BIT (1<<13) + /* * Abuse of the trace_recursion. * As we need a way to maintain state if we are tracing the function |