14a866c567
Impact: new ftrace_graph_stop function While developing more features of function graph, I hit a bug that caused the WARN_ON to trigger in the prepare_ftrace_return function. Well, it was hard for me to find out that was happening because the bug would not print, it would just cause a hard lockup or reboot. The reason is that it is not safe to call printk from this function. Looking further, I also found that it calls unregister_ftrace_graph, which grabs a mutex and calls kstop machine. This would definitely lock the box up if it were to trigger. This patch adds a fast and safe ftrace_graph_stop() which will stop the function tracer. Then it is safe to call the WARN ON. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
394 lines
12 KiB
C
394 lines
12 KiB
C
#ifndef _LINUX_FTRACE_H
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#define _LINUX_FTRACE_H
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#include <linux/linkage.h>
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#include <linux/fs.h>
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#include <linux/ktime.h>
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#include <linux/init.h>
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#include <linux/types.h>
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#include <linux/kallsyms.h>
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#ifdef CONFIG_FUNCTION_TRACER
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extern int ftrace_enabled;
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extern int
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ftrace_enable_sysctl(struct ctl_table *table, int write,
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struct file *filp, void __user *buffer, size_t *lenp,
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loff_t *ppos);
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typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip);
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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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};
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extern int function_trace_stop;
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/*
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* Type of the current tracing.
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*/
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enum ftrace_tracing_type_t {
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FTRACE_TYPE_ENTER = 0, /* Hook the call of the function */
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FTRACE_TYPE_RETURN, /* Hook the return of the function */
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};
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/* Current tracing type, default is FTRACE_TYPE_ENTER */
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extern enum ftrace_tracing_type_t ftrace_tracing_type;
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/**
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* ftrace_stop - stop function tracer.
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*
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* A quick way to stop the function tracer. Note this an on off switch,
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* it is not something that is recursive like preempt_disable.
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* This does not disable the calling of mcount, it only stops the
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* calling of functions from mcount.
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*/
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static inline void ftrace_stop(void)
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{
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function_trace_stop = 1;
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}
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/**
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* ftrace_start - start the function tracer.
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*
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* This function is the inverse of ftrace_stop. This does not enable
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* the function tracing if the function tracer is disabled. This only
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* sets the function tracer flag to continue calling the functions
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* from mcount.
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*/
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static inline void ftrace_start(void)
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{
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function_trace_stop = 0;
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}
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/*
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* The ftrace_ops must be a static and should also
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* be read_mostly. These functions do modify read_mostly variables
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* so use them sparely. Never free an ftrace_op or modify the
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* next pointer after it has been registered. Even after unregistering
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* it, the next pointer may still be used internally.
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*/
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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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extern void ftrace_stub(unsigned long a0, unsigned long a1);
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#else /* !CONFIG_FUNCTION_TRACER */
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# define register_ftrace_function(ops) do { } while (0)
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# define unregister_ftrace_function(ops) do { } while (0)
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# define clear_ftrace_function(ops) do { } while (0)
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static inline void ftrace_kill(void) { }
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static inline void ftrace_stop(void) { }
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static inline void ftrace_start(void) { }
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#endif /* CONFIG_FUNCTION_TRACER */
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#ifdef CONFIG_DYNAMIC_FTRACE
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/* asm/ftrace.h must be defined for archs supporting dynamic ftrace */
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#include <asm/ftrace.h>
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enum {
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FTRACE_FL_FREE = (1 << 0),
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FTRACE_FL_FAILED = (1 << 1),
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FTRACE_FL_FILTER = (1 << 2),
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FTRACE_FL_ENABLED = (1 << 3),
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FTRACE_FL_NOTRACE = (1 << 4),
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FTRACE_FL_CONVERTED = (1 << 5),
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FTRACE_FL_FROZEN = (1 << 6),
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};
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struct dyn_ftrace {
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struct list_head list;
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unsigned long ip; /* address of mcount call-site */
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unsigned long flags;
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struct dyn_arch_ftrace arch;
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};
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int ftrace_force_update(void);
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void ftrace_set_filter(unsigned char *buf, int len, int reset);
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/* defined in arch */
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extern int ftrace_ip_converted(unsigned long ip);
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extern int ftrace_dyn_arch_init(void *data);
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extern int ftrace_update_ftrace_func(ftrace_func_t func);
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extern void ftrace_caller(void);
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extern void ftrace_call(void);
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extern void mcount_call(void);
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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extern void ftrace_graph_caller(void);
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extern int ftrace_enable_ftrace_graph_caller(void);
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extern int ftrace_disable_ftrace_graph_caller(void);
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#else
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static inline int ftrace_enable_ftrace_graph_caller(void) { return 0; }
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static inline int ftrace_disable_ftrace_graph_caller(void) { return 0; }
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#endif
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/**
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* ftrace_make_nop - convert code into top
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* @mod: module structure if called by module load initialization
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* @rec: the mcount call site record
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* @addr: the address that the call site should be calling
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*
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* This is a very sensitive operation and great care needs
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* to be taken by the arch. The operation should carefully
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* read the location, check to see if what is read is indeed
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* what we expect it to be, and then on success of the compare,
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* it should write to the location.
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*
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* The code segment at @rec->ip should be a caller to @addr
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*
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* Return must be:
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* 0 on success
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* -EFAULT on error reading the location
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* -EINVAL on a failed compare of the contents
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* -EPERM on error writing to the location
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* Any other value will be considered a failure.
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*/
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extern int ftrace_make_nop(struct module *mod,
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struct dyn_ftrace *rec, unsigned long addr);
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/**
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* ftrace_make_call - convert a nop call site into a call to addr
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* @rec: the mcount call site record
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* @addr: the address that the call site should call
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*
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* This is a very sensitive operation and great care needs
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* to be taken by the arch. The operation should carefully
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* read the location, check to see if what is read is indeed
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* what we expect it to be, and then on success of the compare,
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* it should write to the location.
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*
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* The code segment at @rec->ip should be a nop
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*
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* Return must be:
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* 0 on success
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* -EFAULT on error reading the location
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* -EINVAL on a failed compare of the contents
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* -EPERM on error writing to the location
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* Any other value will be considered a failure.
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*/
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extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr);
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/* May be defined in arch */
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extern int ftrace_arch_read_dyn_info(char *buf, int size);
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extern int skip_trace(unsigned long ip);
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extern void ftrace_release(void *start, unsigned long size);
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extern void ftrace_disable_daemon(void);
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extern void ftrace_enable_daemon(void);
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#else
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# define skip_trace(ip) ({ 0; })
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# define ftrace_force_update() ({ 0; })
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# define ftrace_set_filter(buf, len, reset) do { } while (0)
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# define ftrace_disable_daemon() do { } while (0)
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# define ftrace_enable_daemon() do { } while (0)
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static inline void ftrace_release(void *start, unsigned long size) { }
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#endif /* CONFIG_DYNAMIC_FTRACE */
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/* totally disable ftrace - can not re-enable after this */
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void ftrace_kill(void);
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static inline void tracer_disable(void)
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{
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#ifdef CONFIG_FUNCTION_TRACER
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ftrace_enabled = 0;
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#endif
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}
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/*
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* Ftrace disable/restore without lock. Some synchronization mechanism
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* must be used to prevent ftrace_enabled to be changed between
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* disable/restore.
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*/
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static inline int __ftrace_enabled_save(void)
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{
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#ifdef CONFIG_FUNCTION_TRACER
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int saved_ftrace_enabled = ftrace_enabled;
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ftrace_enabled = 0;
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return saved_ftrace_enabled;
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#else
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return 0;
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#endif
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}
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static inline void __ftrace_enabled_restore(int enabled)
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{
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#ifdef CONFIG_FUNCTION_TRACER
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ftrace_enabled = enabled;
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#endif
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}
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#ifdef CONFIG_FRAME_POINTER
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/* TODO: need to fix this for ARM */
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# define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
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# define CALLER_ADDR1 ((unsigned long)__builtin_return_address(1))
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# define CALLER_ADDR2 ((unsigned long)__builtin_return_address(2))
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# define CALLER_ADDR3 ((unsigned long)__builtin_return_address(3))
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# define CALLER_ADDR4 ((unsigned long)__builtin_return_address(4))
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# define CALLER_ADDR5 ((unsigned long)__builtin_return_address(5))
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# define CALLER_ADDR6 ((unsigned long)__builtin_return_address(6))
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#else
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# define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
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# define CALLER_ADDR1 0UL
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# define CALLER_ADDR2 0UL
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# define CALLER_ADDR3 0UL
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# define CALLER_ADDR4 0UL
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# define CALLER_ADDR5 0UL
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# define CALLER_ADDR6 0UL
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#endif
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#ifdef CONFIG_IRQSOFF_TRACER
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extern void time_hardirqs_on(unsigned long a0, unsigned long a1);
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extern void time_hardirqs_off(unsigned long a0, unsigned long a1);
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#else
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# define time_hardirqs_on(a0, a1) do { } while (0)
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# define time_hardirqs_off(a0, a1) do { } while (0)
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#endif
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#ifdef CONFIG_PREEMPT_TRACER
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extern void trace_preempt_on(unsigned long a0, unsigned long a1);
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extern void trace_preempt_off(unsigned long a0, unsigned long a1);
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#else
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# define trace_preempt_on(a0, a1) do { } while (0)
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# define trace_preempt_off(a0, a1) do { } while (0)
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#endif
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#ifdef CONFIG_TRACING
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extern int ftrace_dump_on_oops;
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extern void tracing_start(void);
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extern void tracing_stop(void);
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extern void ftrace_off_permanent(void);
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extern void
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ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3);
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/**
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* ftrace_printk - printf formatting in the ftrace buffer
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* @fmt: the printf format for printing
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*
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* Note: __ftrace_printk is an internal function for ftrace_printk and
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* the @ip is passed in via the ftrace_printk macro.
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*
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* This function allows a kernel developer to debug fast path sections
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* that printk is not appropriate for. By scattering in various
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* printk like tracing in the code, a developer can quickly see
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* where problems are occurring.
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*
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* This is intended as a debugging tool for the developer only.
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* Please refrain from leaving ftrace_printks scattered around in
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* your code.
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*/
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# define ftrace_printk(fmt...) __ftrace_printk(_THIS_IP_, fmt)
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extern int
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__ftrace_printk(unsigned long ip, const char *fmt, ...)
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__attribute__ ((format (printf, 2, 3)));
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extern void ftrace_dump(void);
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#else
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static inline void
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ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
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static inline int
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ftrace_printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 0)));
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static inline void tracing_start(void) { }
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static inline void tracing_stop(void) { }
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static inline void ftrace_off_permanent(void) { }
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static inline int
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ftrace_printk(const char *fmt, ...)
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{
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return 0;
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}
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static inline void ftrace_dump(void) { }
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#endif
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#ifdef CONFIG_FTRACE_MCOUNT_RECORD
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extern void ftrace_init(void);
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extern void ftrace_init_module(struct module *mod,
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unsigned long *start, unsigned long *end);
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#else
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static inline void ftrace_init(void) { }
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static inline void
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ftrace_init_module(struct module *mod,
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unsigned long *start, unsigned long *end) { }
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#endif
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enum {
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POWER_NONE = 0,
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POWER_CSTATE = 1,
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POWER_PSTATE = 2,
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};
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struct power_trace {
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#ifdef CONFIG_POWER_TRACER
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ktime_t stamp;
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ktime_t end;
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int type;
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int state;
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#endif
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};
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#ifdef CONFIG_POWER_TRACER
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extern void trace_power_start(struct power_trace *it, unsigned int type,
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unsigned int state);
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extern void trace_power_mark(struct power_trace *it, unsigned int type,
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unsigned int state);
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extern void trace_power_end(struct power_trace *it);
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#else
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static inline void trace_power_start(struct power_trace *it, unsigned int type,
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unsigned int state) { }
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static inline void trace_power_mark(struct power_trace *it, unsigned int type,
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unsigned int state) { }
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static inline void trace_power_end(struct power_trace *it) { }
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#endif
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/*
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* Structure that defines an entry function trace.
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*/
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struct ftrace_graph_ent {
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unsigned long func; /* Current function */
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int depth;
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};
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/*
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* Structure that defines a return function trace.
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*/
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struct ftrace_graph_ret {
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unsigned long func; /* Current function */
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unsigned long long calltime;
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unsigned long long rettime;
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/* Number of functions that overran the depth limit for current task */
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unsigned long overrun;
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int depth;
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};
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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#define FTRACE_RETFUNC_DEPTH 50
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#define FTRACE_RETSTACK_ALLOC_SIZE 32
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/* Type of the callback handlers for tracing function graph*/
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typedef void (*trace_func_graph_ret_t)(struct ftrace_graph_ret *); /* return */
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typedef void (*trace_func_graph_ent_t)(struct ftrace_graph_ent *); /* entry */
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extern int register_ftrace_graph(trace_func_graph_ret_t retfunc,
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trace_func_graph_ent_t entryfunc);
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extern void ftrace_graph_stop(void);
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/* The current handlers in use */
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extern trace_func_graph_ret_t ftrace_graph_return;
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extern trace_func_graph_ent_t ftrace_graph_entry;
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extern void unregister_ftrace_graph(void);
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extern void ftrace_graph_init_task(struct task_struct *t);
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extern void ftrace_graph_exit_task(struct task_struct *t);
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#else
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static inline void ftrace_graph_init_task(struct task_struct *t) { }
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static inline void ftrace_graph_exit_task(struct task_struct *t) { }
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#endif
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#endif /* _LINUX_FTRACE_H */
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