ftrace: Add enable/disable ftrace_ops control interface
Adding a way to temporarily enable/disable ftrace_ops. The change follows the same way as 'global' ftrace_ops are done. Introducing 2 global ftrace_ops - control_ops and ftrace_control_list which take over all ftrace_ops registered with FTRACE_OPS_FL_CONTROL flag. In addition new per cpu flag called 'disabled' is also added to ftrace_ops to provide the control information for each cpu. When ftrace_ops with FTRACE_OPS_FL_CONTROL is registered, it is set as disabled for all cpus. The ftrace_control_list contains all the registered 'control' ftrace_ops. The control_ops provides function which iterates ftrace_control_list and does the check for 'disabled' flag on current cpu. Adding 3 inline functions: ftrace_function_local_disable/ftrace_function_local_enable - enable/disable the ftrace_ops on current cpu ftrace_function_local_disabled - get disabled ftrace_ops::disabled value for current cpu Link: http://lkml.kernel.org/r/1329317514-8131-2-git-send-email-jolsa@redhat.com Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Jiri Olsa
Steven Rostedt
Родитель
5b34926114
Коммит
e248491ac2
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@ -31,16 +31,33 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
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typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip);
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/*
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* FTRACE_OPS_FL_* bits denote the state of ftrace_ops struct and are
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* set in the flags member.
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*
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* ENABLED - set/unset when ftrace_ops is registered/unregistered
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* GLOBAL - set manualy by ftrace_ops user to denote the ftrace_ops
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* is part of the global tracers sharing the same filter
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* via set_ftrace_* debugfs files.
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* DYNAMIC - set when ftrace_ops is registered to denote dynamically
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* allocated ftrace_ops which need special care
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* CONTROL - set manualy by ftrace_ops user to denote the ftrace_ops
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* could be controled by following calls:
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* ftrace_function_local_enable
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* ftrace_function_local_disable
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*/
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enum {
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FTRACE_OPS_FL_ENABLED = 1 << 0,
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FTRACE_OPS_FL_GLOBAL = 1 << 1,
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FTRACE_OPS_FL_DYNAMIC = 1 << 2,
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FTRACE_OPS_FL_CONTROL = 1 << 3,
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};
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struct ftrace_ops {
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ftrace_func_t func;
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struct ftrace_ops *next;
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unsigned long flags;
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int __percpu *disabled;
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#ifdef CONFIG_DYNAMIC_FTRACE
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struct ftrace_hash *notrace_hash;
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struct ftrace_hash *filter_hash;
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@ -97,6 +114,55 @@ int register_ftrace_function(struct ftrace_ops *ops);
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int unregister_ftrace_function(struct ftrace_ops *ops);
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void clear_ftrace_function(void);
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/**
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* ftrace_function_local_enable - enable controlled ftrace_ops on current cpu
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*
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* This function enables tracing on current cpu by decreasing
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* the per cpu control variable.
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* It must be called with preemption disabled and only on ftrace_ops
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* registered with FTRACE_OPS_FL_CONTROL. If called without preemption
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* disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
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*/
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static inline void ftrace_function_local_enable(struct ftrace_ops *ops)
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{
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if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL)))
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return;
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(*this_cpu_ptr(ops->disabled))--;
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}
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/**
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* ftrace_function_local_disable - enable controlled ftrace_ops on current cpu
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*
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* This function enables tracing on current cpu by decreasing
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* the per cpu control variable.
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* It must be called with preemption disabled and only on ftrace_ops
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* registered with FTRACE_OPS_FL_CONTROL. If called without preemption
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* disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
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*/
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static inline void ftrace_function_local_disable(struct ftrace_ops *ops)
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{
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if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL)))
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return;
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(*this_cpu_ptr(ops->disabled))++;
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}
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/**
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* ftrace_function_local_disabled - returns ftrace_ops disabled value
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* on current cpu
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*
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* This function returns value of ftrace_ops::disabled on current cpu.
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* It must be called with preemption disabled and only on ftrace_ops
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* registered with FTRACE_OPS_FL_CONTROL. If called without preemption
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* disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
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*/
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static inline int ftrace_function_local_disabled(struct ftrace_ops *ops)
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{
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WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL));
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return *this_cpu_ptr(ops->disabled);
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}
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extern void ftrace_stub(unsigned long a0, unsigned long a1);
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#else /* !CONFIG_FUNCTION_TRACER */
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@ -62,6 +62,8 @@
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#define FTRACE_HASH_DEFAULT_BITS 10
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#define FTRACE_HASH_MAX_BITS 12
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#define FL_GLOBAL_CONTROL_MASK (FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_CONTROL)
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/* ftrace_enabled is a method to turn ftrace on or off */
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int ftrace_enabled __read_mostly;
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static int last_ftrace_enabled;
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@ -89,12 +91,14 @@ static struct ftrace_ops ftrace_list_end __read_mostly = {
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};
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static struct ftrace_ops *ftrace_global_list __read_mostly = &ftrace_list_end;
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static struct ftrace_ops *ftrace_control_list __read_mostly = &ftrace_list_end;
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static struct ftrace_ops *ftrace_ops_list __read_mostly = &ftrace_list_end;
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ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
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static ftrace_func_t __ftrace_trace_function_delay __read_mostly = ftrace_stub;
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ftrace_func_t __ftrace_trace_function __read_mostly = ftrace_stub;
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ftrace_func_t ftrace_pid_function __read_mostly = ftrace_stub;
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static struct ftrace_ops global_ops;
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static struct ftrace_ops control_ops;
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static void
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ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip);
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@ -168,6 +172,32 @@ static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip)
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}
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#endif
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static void control_ops_disable_all(struct ftrace_ops *ops)
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{
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int cpu;
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for_each_possible_cpu(cpu)
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*per_cpu_ptr(ops->disabled, cpu) = 1;
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}
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static int control_ops_alloc(struct ftrace_ops *ops)
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{
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int __percpu *disabled;
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disabled = alloc_percpu(int);
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if (!disabled)
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return -ENOMEM;
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ops->disabled = disabled;
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control_ops_disable_all(ops);
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return 0;
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}
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static void control_ops_free(struct ftrace_ops *ops)
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{
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free_percpu(ops->disabled);
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}
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static void update_global_ops(void)
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{
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ftrace_func_t func;
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@ -259,6 +289,26 @@ static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
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return 0;
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}
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static void add_ftrace_list_ops(struct ftrace_ops **list,
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struct ftrace_ops *main_ops,
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struct ftrace_ops *ops)
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{
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int first = *list == &ftrace_list_end;
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add_ftrace_ops(list, ops);
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if (first)
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add_ftrace_ops(&ftrace_ops_list, main_ops);
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}
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static int remove_ftrace_list_ops(struct ftrace_ops **list,
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struct ftrace_ops *main_ops,
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struct ftrace_ops *ops)
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{
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int ret = remove_ftrace_ops(list, ops);
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if (!ret && *list == &ftrace_list_end)
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ret = remove_ftrace_ops(&ftrace_ops_list, main_ops);
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return ret;
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}
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static int __register_ftrace_function(struct ftrace_ops *ops)
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{
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if (ftrace_disabled)
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@ -270,15 +320,20 @@ static int __register_ftrace_function(struct ftrace_ops *ops)
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if (WARN_ON(ops->flags & FTRACE_OPS_FL_ENABLED))
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return -EBUSY;
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/* We don't support both control and global flags set. */
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if ((ops->flags & FL_GLOBAL_CONTROL_MASK) == FL_GLOBAL_CONTROL_MASK)
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return -EINVAL;
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if (!core_kernel_data((unsigned long)ops))
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ops->flags |= FTRACE_OPS_FL_DYNAMIC;
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if (ops->flags & FTRACE_OPS_FL_GLOBAL) {
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int first = ftrace_global_list == &ftrace_list_end;
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add_ftrace_ops(&ftrace_global_list, ops);
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add_ftrace_list_ops(&ftrace_global_list, &global_ops, ops);
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ops->flags |= FTRACE_OPS_FL_ENABLED;
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if (first)
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add_ftrace_ops(&ftrace_ops_list, &global_ops);
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} else if (ops->flags & FTRACE_OPS_FL_CONTROL) {
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if (control_ops_alloc(ops))
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return -ENOMEM;
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add_ftrace_list_ops(&ftrace_control_list, &control_ops, ops);
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} else
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add_ftrace_ops(&ftrace_ops_list, ops);
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@ -302,11 +357,23 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
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return -EINVAL;
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if (ops->flags & FTRACE_OPS_FL_GLOBAL) {
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ret = remove_ftrace_ops(&ftrace_global_list, ops);
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if (!ret && ftrace_global_list == &ftrace_list_end)
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ret = remove_ftrace_ops(&ftrace_ops_list, &global_ops);
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ret = remove_ftrace_list_ops(&ftrace_global_list,
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&global_ops, ops);
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if (!ret)
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ops->flags &= ~FTRACE_OPS_FL_ENABLED;
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} else if (ops->flags & FTRACE_OPS_FL_CONTROL) {
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ret = remove_ftrace_list_ops(&ftrace_control_list,
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&control_ops, ops);
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if (!ret) {
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/*
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* The ftrace_ops is now removed from the list,
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* so there'll be no new users. We must ensure
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* all current users are done before we free
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* the control data.
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*/
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synchronize_sched();
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control_ops_free(ops);
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}
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} else
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ret = remove_ftrace_ops(&ftrace_ops_list, ops);
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@ -3873,6 +3940,36 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip)
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#endif /* CONFIG_DYNAMIC_FTRACE */
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static void
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ftrace_ops_control_func(unsigned long ip, unsigned long parent_ip)
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{
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struct ftrace_ops *op;
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if (unlikely(trace_recursion_test(TRACE_CONTROL_BIT)))
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return;
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/*
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* Some of the ops may be dynamically allocated,
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* they must be freed after a synchronize_sched().
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*/
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preempt_disable_notrace();
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trace_recursion_set(TRACE_CONTROL_BIT);
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op = rcu_dereference_raw(ftrace_control_list);
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while (op != &ftrace_list_end) {
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if (!ftrace_function_local_disabled(op) &&
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ftrace_ops_test(op, ip))
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op->func(ip, parent_ip);
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op = rcu_dereference_raw(op->next);
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};
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trace_recursion_clear(TRACE_CONTROL_BIT);
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preempt_enable_notrace();
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}
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static struct ftrace_ops control_ops = {
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.func = ftrace_ops_control_func,
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};
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static void
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ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
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{
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@ -288,6 +288,8 @@ struct tracer {
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/* for function tracing recursion */
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#define TRACE_INTERNAL_BIT (1<<11)
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#define TRACE_GLOBAL_BIT (1<<12)
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#define TRACE_CONTROL_BIT (1<<13)
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/*
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* Abuse of the trace_recursion.
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* As we need a way to maintain state if we are tracing the function
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