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3a630178fd
Dave Jones reported seeing a bug from one of my TLB tracepoints: http://lkml.kernel.org/r/20140806181801.GA4605@redhat.com I've been running these patches for months and never saw this. But, a big chunk of my testing, especially with all the debugging enabled, was in a vm where intel_idle doesn't work. On the systems where I was using intel_idle, I never had lockdep enabled and this tracepoint on at the same time. This patch ensures that whenever we have lockdep available, we do _some_ RCU activity at the site of the tracepoint, despite whether the tracepoint's condition matches or even if the tracepoint itself is completely disabled. This is a bit of a hack, but it is pretty self-contained. I confirmed that with this patch plus lockdep I get the same splat as Dave Jones did, but without enabling the tracepoint explicitly. Link: http://lkml.kernel.org/p/20140807175204.C257CAC5@viggo.jf.intel.com Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Dave Hansen <dave@sr71.net> Cc: Dave Jones <davej@redhat.com>, Cc: paulmck@linux.vnet.ibm.com Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
473 lines
15 KiB
C
473 lines
15 KiB
C
#ifndef _LINUX_TRACEPOINT_H
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#define _LINUX_TRACEPOINT_H
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/*
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* Kernel Tracepoint API.
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*
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* See Documentation/trace/tracepoints.txt.
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*
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* Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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*
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* Heavily inspired from the Linux Kernel Markers.
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*
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* This file is released under the GPLv2.
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* See the file COPYING for more details.
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*/
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#include <linux/errno.h>
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#include <linux/types.h>
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#include <linux/rcupdate.h>
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#include <linux/static_key.h>
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struct module;
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struct tracepoint;
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struct notifier_block;
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struct tracepoint_func {
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void *func;
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void *data;
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};
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struct tracepoint {
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const char *name; /* Tracepoint name */
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struct static_key key;
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void (*regfunc)(void);
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void (*unregfunc)(void);
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struct tracepoint_func __rcu *funcs;
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};
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extern int
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tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
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extern int
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tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
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extern void
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for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
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void *priv);
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#ifdef CONFIG_MODULES
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struct tp_module {
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struct list_head list;
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struct module *mod;
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};
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bool trace_module_has_bad_taint(struct module *mod);
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extern int register_tracepoint_module_notifier(struct notifier_block *nb);
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extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
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#else
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static inline bool trace_module_has_bad_taint(struct module *mod)
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{
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return false;
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}
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static inline
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int register_tracepoint_module_notifier(struct notifier_block *nb)
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{
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return 0;
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}
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static inline
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int unregister_tracepoint_module_notifier(struct notifier_block *nb)
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{
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return 0;
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}
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#endif /* CONFIG_MODULES */
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/*
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* tracepoint_synchronize_unregister must be called between the last tracepoint
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* probe unregistration and the end of module exit to make sure there is no
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* caller executing a probe when it is freed.
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*/
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static inline void tracepoint_synchronize_unregister(void)
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{
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synchronize_sched();
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}
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#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
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extern void syscall_regfunc(void);
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extern void syscall_unregfunc(void);
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#endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
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#define PARAMS(args...) args
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#endif /* _LINUX_TRACEPOINT_H */
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/*
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* Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
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* file ifdef protection.
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* This is due to the way trace events work. If a file includes two
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* trace event headers under one "CREATE_TRACE_POINTS" the first include
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* will override the TRACE_EVENT and break the second include.
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*/
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#ifndef DECLARE_TRACE
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#define TP_PROTO(args...) args
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#define TP_ARGS(args...) args
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#define TP_CONDITION(args...) args
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#ifdef CONFIG_TRACEPOINTS
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/*
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* it_func[0] is never NULL because there is at least one element in the array
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* when the array itself is non NULL.
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*
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* Note, the proto and args passed in includes "__data" as the first parameter.
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* The reason for this is to handle the "void" prototype. If a tracepoint
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* has a "void" prototype, then it is invalid to declare a function
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* as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
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* "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
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*/
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#define __DO_TRACE(tp, proto, args, cond, prercu, postrcu) \
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do { \
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struct tracepoint_func *it_func_ptr; \
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void *it_func; \
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void *__data; \
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\
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if (!(cond)) \
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return; \
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prercu; \
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rcu_read_lock_sched_notrace(); \
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it_func_ptr = rcu_dereference_sched((tp)->funcs); \
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if (it_func_ptr) { \
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do { \
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it_func = (it_func_ptr)->func; \
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__data = (it_func_ptr)->data; \
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((void(*)(proto))(it_func))(args); \
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} while ((++it_func_ptr)->func); \
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} \
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rcu_read_unlock_sched_notrace(); \
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postrcu; \
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} while (0)
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#ifndef MODULE
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#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
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static inline void trace_##name##_rcuidle(proto) \
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{ \
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if (static_key_false(&__tracepoint_##name.key)) \
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__DO_TRACE(&__tracepoint_##name, \
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TP_PROTO(data_proto), \
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TP_ARGS(data_args), \
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TP_CONDITION(cond), \
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rcu_irq_enter(), \
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rcu_irq_exit()); \
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}
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#else
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#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
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#endif
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/*
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* Make sure the alignment of the structure in the __tracepoints section will
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* not add unwanted padding between the beginning of the section and the
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* structure. Force alignment to the same alignment as the section start.
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*
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* When lockdep is enabled, we make sure to always do the RCU portions of
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* the tracepoint code, regardless of whether tracing is on or we match the
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* condition. This lets us find RCU issues triggered with tracepoints even
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* when this tracepoint is off. This code has no purpose other than poking
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* RCU a bit.
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*/
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#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
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extern struct tracepoint __tracepoint_##name; \
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static inline void trace_##name(proto) \
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{ \
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if (static_key_false(&__tracepoint_##name.key)) \
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__DO_TRACE(&__tracepoint_##name, \
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TP_PROTO(data_proto), \
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TP_ARGS(data_args), \
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TP_CONDITION(cond),,); \
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if (IS_ENABLED(CONFIG_LOCKDEP)) { \
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rcu_read_lock_sched_notrace(); \
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rcu_dereference_sched(__tracepoint_##name.funcs);\
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rcu_read_unlock_sched_notrace(); \
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} \
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} \
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__DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
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PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
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static inline int \
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register_trace_##name(void (*probe)(data_proto), void *data) \
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{ \
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return tracepoint_probe_register(&__tracepoint_##name, \
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(void *)probe, data); \
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} \
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static inline int \
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unregister_trace_##name(void (*probe)(data_proto), void *data) \
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{ \
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return tracepoint_probe_unregister(&__tracepoint_##name,\
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(void *)probe, data); \
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} \
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static inline void \
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check_trace_callback_type_##name(void (*cb)(data_proto)) \
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{ \
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} \
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static inline bool \
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trace_##name##_enabled(void) \
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{ \
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return static_key_false(&__tracepoint_##name.key); \
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}
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/*
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* We have no guarantee that gcc and the linker won't up-align the tracepoint
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* structures, so we create an array of pointers that will be used for iteration
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* on the tracepoints.
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*/
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#define DEFINE_TRACE_FN(name, reg, unreg) \
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static const char __tpstrtab_##name[] \
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__attribute__((section("__tracepoints_strings"))) = #name; \
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struct tracepoint __tracepoint_##name \
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__attribute__((section("__tracepoints"))) = \
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{ __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
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static struct tracepoint * const __tracepoint_ptr_##name __used \
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__attribute__((section("__tracepoints_ptrs"))) = \
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&__tracepoint_##name;
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#define DEFINE_TRACE(name) \
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DEFINE_TRACE_FN(name, NULL, NULL);
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#define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
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EXPORT_SYMBOL_GPL(__tracepoint_##name)
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#define EXPORT_TRACEPOINT_SYMBOL(name) \
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EXPORT_SYMBOL(__tracepoint_##name)
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#else /* !CONFIG_TRACEPOINTS */
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#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
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static inline void trace_##name(proto) \
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{ } \
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static inline void trace_##name##_rcuidle(proto) \
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{ } \
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static inline int \
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register_trace_##name(void (*probe)(data_proto), \
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void *data) \
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{ \
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return -ENOSYS; \
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} \
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static inline int \
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unregister_trace_##name(void (*probe)(data_proto), \
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void *data) \
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{ \
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return -ENOSYS; \
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} \
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static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
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{ \
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} \
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static inline bool \
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trace_##name##_enabled(void) \
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{ \
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return false; \
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}
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#define DEFINE_TRACE_FN(name, reg, unreg)
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#define DEFINE_TRACE(name)
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#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
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#define EXPORT_TRACEPOINT_SYMBOL(name)
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#endif /* CONFIG_TRACEPOINTS */
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#ifdef CONFIG_TRACING
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/**
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* tracepoint_string - register constant persistent string to trace system
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* @str - a constant persistent string that will be referenced in tracepoints
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*
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* If constant strings are being used in tracepoints, it is faster and
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* more efficient to just save the pointer to the string and reference
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* that with a printf "%s" instead of saving the string in the ring buffer
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* and wasting space and time.
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*
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* The problem with the above approach is that userspace tools that read
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* the binary output of the trace buffers do not have access to the string.
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* Instead they just show the address of the string which is not very
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* useful to users.
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*
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* With tracepoint_string(), the string will be registered to the tracing
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* system and exported to userspace via the debugfs/tracing/printk_formats
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* file that maps the string address to the string text. This way userspace
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* tools that read the binary buffers have a way to map the pointers to
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* the ASCII strings they represent.
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*
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* The @str used must be a constant string and persistent as it would not
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* make sense to show a string that no longer exists. But it is still fine
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* to be used with modules, because when modules are unloaded, if they
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* had tracepoints, the ring buffers are cleared too. As long as the string
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* does not change during the life of the module, it is fine to use
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* tracepoint_string() within a module.
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*/
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#define tracepoint_string(str) \
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({ \
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static const char *___tp_str __tracepoint_string = str; \
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___tp_str; \
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})
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#define __tracepoint_string __attribute__((section("__tracepoint_str")))
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#else
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/*
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* tracepoint_string() is used to save the string address for userspace
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* tracing tools. When tracing isn't configured, there's no need to save
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* anything.
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*/
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# define tracepoint_string(str) str
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# define __tracepoint_string
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#endif
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/*
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* The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
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* (void). "void" is a special value in a function prototype and can
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* not be combined with other arguments. Since the DECLARE_TRACE()
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* macro adds a data element at the beginning of the prototype,
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* we need a way to differentiate "(void *data, proto)" from
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* "(void *data, void)". The second prototype is invalid.
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*
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* DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
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* and "void *__data" as the callback prototype.
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*
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* DECLARE_TRACE() passes "proto" as the tracepoint protoype and
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* "void *__data, proto" as the callback prototype.
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*/
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#define DECLARE_TRACE_NOARGS(name) \
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__DECLARE_TRACE(name, void, , 1, void *__data, __data)
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#define DECLARE_TRACE(name, proto, args) \
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__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1, \
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PARAMS(void *__data, proto), \
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PARAMS(__data, args))
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#define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
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__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
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PARAMS(void *__data, proto), \
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PARAMS(__data, args))
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#define TRACE_EVENT_FLAGS(event, flag)
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#define TRACE_EVENT_PERF_PERM(event, expr...)
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#endif /* DECLARE_TRACE */
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#ifndef TRACE_EVENT
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/*
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* For use with the TRACE_EVENT macro:
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*
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* We define a tracepoint, its arguments, its printk format
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* and its 'fast binary record' layout.
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*
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* Firstly, name your tracepoint via TRACE_EVENT(name : the
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* 'subsystem_event' notation is fine.
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*
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* Think about this whole construct as the
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* 'trace_sched_switch() function' from now on.
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*
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*
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* TRACE_EVENT(sched_switch,
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*
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* *
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* * A function has a regular function arguments
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* * prototype, declare it via TP_PROTO():
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* *
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*
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* TP_PROTO(struct rq *rq, struct task_struct *prev,
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* struct task_struct *next),
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*
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* *
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* * Define the call signature of the 'function'.
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* * (Design sidenote: we use this instead of a
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* * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
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* *
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*
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* TP_ARGS(rq, prev, next),
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*
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* *
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* * Fast binary tracing: define the trace record via
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* * TP_STRUCT__entry(). You can think about it like a
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* * regular C structure local variable definition.
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* *
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* * This is how the trace record is structured and will
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* * be saved into the ring buffer. These are the fields
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* * that will be exposed to user-space in
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* * /sys/kernel/debug/tracing/events/<*>/format.
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* *
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* * The declared 'local variable' is called '__entry'
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* *
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* * __field(pid_t, prev_prid) is equivalent to a standard declariton:
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* *
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* * pid_t prev_pid;
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* *
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* * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
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* *
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* * char prev_comm[TASK_COMM_LEN];
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* *
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*
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* TP_STRUCT__entry(
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* __array( char, prev_comm, TASK_COMM_LEN )
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* __field( pid_t, prev_pid )
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* __field( int, prev_prio )
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* __array( char, next_comm, TASK_COMM_LEN )
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* __field( pid_t, next_pid )
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* __field( int, next_prio )
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* ),
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*
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* *
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* * Assign the entry into the trace record, by embedding
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* * a full C statement block into TP_fast_assign(). You
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* * can refer to the trace record as '__entry' -
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* * otherwise you can put arbitrary C code in here.
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* *
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* * Note: this C code will execute every time a trace event
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* * happens, on an active tracepoint.
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* *
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*
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* TP_fast_assign(
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* memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
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* __entry->prev_pid = prev->pid;
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* __entry->prev_prio = prev->prio;
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* memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
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* __entry->next_pid = next->pid;
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* __entry->next_prio = next->prio;
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* ),
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*
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* *
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* * Formatted output of a trace record via TP_printk().
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* * This is how the tracepoint will appear under ftrace
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* * plugins that make use of this tracepoint.
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* *
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* * (raw-binary tracing wont actually perform this step.)
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* *
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*
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* TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
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* __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
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* __entry->next_comm, __entry->next_pid, __entry->next_prio),
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*
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* );
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*
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* This macro construct is thus used for the regular printk format
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* tracing setup, it is used to construct a function pointer based
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* tracepoint callback (this is used by programmatic plugins and
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* can also by used by generic instrumentation like SystemTap), and
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* it is also used to expose a structured trace record in
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* /sys/kernel/debug/tracing/events/.
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*
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* A set of (un)registration functions can be passed to the variant
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* TRACE_EVENT_FN to perform any (un)registration work.
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*/
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#define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
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#define DEFINE_EVENT(template, name, proto, args) \
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DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
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#define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
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DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
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#define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
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DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
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#define DEFINE_EVENT_CONDITION(template, name, proto, \
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args, cond) \
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DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
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PARAMS(args), PARAMS(cond))
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#define TRACE_EVENT(name, proto, args, struct, assign, print) \
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DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
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#define TRACE_EVENT_FN(name, proto, args, struct, \
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assign, print, reg, unreg) \
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DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
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#define TRACE_EVENT_CONDITION(name, proto, args, cond, \
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struct, assign, print) \
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DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
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PARAMS(args), PARAMS(cond))
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#define TRACE_EVENT_FLAGS(event, flag)
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#define TRACE_EVENT_PERF_PERM(event, expr...)
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#endif /* ifdef TRACE_EVENT (see note above) */
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