| Message ID | 1472544450-9915-2-git-send-email-zhang.chunyan@linaro.org |
|---|---|
| State | New |
| Headers | show |
On 30 August 2016 at 22:30, Steven Rostedt <rostedt@goodmis.org> wrote: > On Tue, 30 Aug 2016 16:07:28 +0800 > Chunyan Zhang <zhang.chunyan@linaro.org> wrote: > >> Currently Function traces can be only exported to ring buffer, this >> patch added trace_export concept which can process traces and export >> them to a registered destination as an addition to the current only >> output of Ftrace - i.e. ring buffer. >> >> In this way, if we want Function traces to be sent to other destination >> rather than ring buffer only, we just need to register a new >> trace_export and implement its own .commit() callback or just use >> 'trace_generic_commit()' which this patch also added and hooks up its >> own .write() function for writing traces to the storage. >> >> With this patch, only Function trace (trace type is TRACE_FN) >> is supported. >> >> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org> >> --- >> include/linux/trace.h | 35 ++++++++++++ >> kernel/trace/trace.c | 155 +++++++++++++++++++++++++++++++++++++++++++++++++- >> kernel/trace/trace.h | 1 + >> 3 files changed, 190 insertions(+), 1 deletion(-) >> create mode 100644 include/linux/trace.h >> >> diff --git a/include/linux/trace.h b/include/linux/trace.h >> new file mode 100644 >> index 0000000..30ded92 >> --- /dev/null >> +++ b/include/linux/trace.h >> @@ -0,0 +1,35 @@ >> +#ifndef _LINUX_TRACE_H >> +#define _LINUX_TRACE_H >> + >> +#include <linux/ring_buffer.h> >> +struct trace_array; >> + >> +#ifdef CONFIG_TRACING >> +/* >> + * The trace export - an export of Ftrace. The trace_export can process >> + * traces and export them to a registered destination as an addition to >> + * the current only output of Ftrace - i.e. ring buffer. >> + * >> + * If you want traces to be sent to some other place rather than >> + * ring buffer only, just need to register a new trace_export and >> + * implement its own .commit() callback or just directly use >> + * 'trace_generic_commit()' and hooks up its own .write() function >> + * for writing traces to the storage. >> + * >> + * next - pointer to the next trace_export >> + * commit - commit the traces to the destination >> + * write - copy traces which have been delt with ->commit() to >> + * the destination >> + */ >> +struct trace_export { >> + struct trace_export __rcu *next; >> + void (*commit)(struct trace_array *, struct ring_buffer_event *); >> + void (*write)(const char *, unsigned int); >> +}; >> + >> +int register_ftrace_export(struct trace_export *export); >> +int unregister_ftrace_export(struct trace_export *export); >> + >> +#endif /* CONFIG_TRACING */ >> + >> +#endif /* _LINUX_TRACE_H */ >> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c >> index dade4c9..3163fa6 100644 >> --- a/kernel/trace/trace.c >> +++ b/kernel/trace/trace.c >> @@ -40,6 +40,7 @@ >> #include <linux/poll.h> >> #include <linux/nmi.h> >> #include <linux/fs.h> >> +#include <linux/trace.h> >> #include <linux/sched/rt.h> >> >> #include "trace.h" >> @@ -2128,6 +2129,155 @@ void trace_buffer_unlock_commit_regs(struct trace_array *tr, >> ftrace_trace_userstack(buffer, flags, pc); >> } >> >> +static DEFINE_STATIC_KEY_FALSE(ftrace_exports_enabled); >> + >> +static void ftrace_exports_enable(void) >> +{ >> + static_branch_enable(&ftrace_exports_enabled); >> +} >> + >> +static void ftrace_exports_disable(void) >> +{ >> + static_branch_disable(&ftrace_exports_enabled); >> +} >> + >> +static size_t trace_size[] = { >> + [TRACE_FN] = sizeof(struct ftrace_entry), >> + [TRACE_CTX] = sizeof(struct ctx_switch_entry), >> + [TRACE_WAKE] = sizeof(struct ctx_switch_entry), >> + [TRACE_STACK] = sizeof(struct stack_entry), >> + [TRACE_PRINT] = sizeof(struct print_entry), >> + [TRACE_BPRINT] = sizeof(struct bprint_entry), >> + [TRACE_MMIO_RW] = sizeof(struct trace_mmiotrace_rw), >> + [TRACE_MMIO_MAP] = sizeof(struct trace_mmiotrace_map), >> + [TRACE_BRANCH] = sizeof(struct trace_branch), >> + [TRACE_GRAPH_RET] = sizeof(struct ftrace_graph_ret_entry), >> + [TRACE_GRAPH_ENT] = sizeof(struct ftrace_graph_ent_entry), >> + [TRACE_USER_STACK] = sizeof(struct userstack_entry), >> + [TRACE_BPUTS] = sizeof(struct bputs_entry), >> +}; >> + >> +static void >> +trace_generic_commit(struct trace_array *tr, >> + struct ring_buffer_event *event) >> +{ >> + struct trace_entry *entry; >> + struct trace_export *export = tr->export; > > Why not just pass in the export directly? > >> + unsigned int size = 0; >> + >> + entry = ring_buffer_event_data(event); >> + >> + size = trace_size[entry->type]; > > BTW, it would make much more sense if you just did: > > size = ring_buffer_event_length(event); > > and get rid of that silly array, as that is prone to bugs if you add a > new type. > >> + if (!size) >> + return; >> + >> + if (export && export->write) >> + export->write((char *)entry, size); >> +} >> + >> +static DEFINE_MUTEX(ftrace_export_lock); >> + >> +static struct trace_export __rcu *ftrace_exports_list __read_mostly; >> + >> +static inline void >> +ftrace_exports(struct trace_array *tr, struct ring_buffer_event *event) >> +{ >> + struct trace_export *export; >> + >> + preempt_disable_notrace(); >> + >> + for (export = rcu_dereference_raw_notrace(ftrace_exports_list); >> + export && export->commit; >> + export = rcu_dereference_raw_notrace(export->next)) { >> + tr->export = export; >> + export->commit(tr, event); > > Um, what's the commit for? > > Why not just call the trace_generic_commit() above. Nothing has The original thought was that allow other export (maybe added in the future) to implement its own .commit(). But I accept your suggestion since there's no other trace_export so far rather than stm_ftrace only, the modification should be kept as simple as it can be. Thanks for your review, Chunyan > anything different. But change that name. Maybe call it > "process_export()" or something. And pass the export directly and get > rid of the tr->export. > >> + } >> + >> + preempt_enable_notrace(); >> +} >> + >> +static inline void >> +add_trace_export(struct trace_export **list, struct trace_export *export) >> +{ >> + rcu_assign_pointer(export->next, *list); >> + /* >> + * We are entering export into the list but another >> + * CPU might be walking that list. We need to make sure >> + * the export->next pointer is valid before another CPU sees >> + * the export pointer included into the list. >> + */ >> + rcu_assign_pointer(*list, export); >> +} >> + >> +static inline int >> +rm_trace_export(struct trace_export **list, struct trace_export *export) >> +{ >> + struct trace_export **p; >> + >> + for (p = list; *p != NULL; p = &(*p)->next) >> + if (*p == export) >> + break; >> + >> + if (*p != export) >> + return -1; >> + >> + rcu_assign_pointer(*p, (*p)->next); >> + >> + return 0; >> +} >> + >> +static inline void >> +add_ftrace_export(struct trace_export **list, struct trace_export *export) >> +{ >> + if (*list == NULL) >> + ftrace_exports_enable(); >> + >> + add_trace_export(list, export); >> +} >> + >> +static inline int >> +rm_ftrace_export(struct trace_export **list, struct trace_export *export) >> +{ >> + int ret; >> + >> + ret = rm_trace_export(list, export); >> + if (*list == NULL) >> + ftrace_exports_disable(); >> + >> + return ret; >> +} >> + >> +int register_ftrace_export(struct trace_export *export) >> +{ >> + if (WARN_ON_ONCE(!export->write)) >> + return -1; >> + >> + mutex_lock(&ftrace_export_lock); >> + >> + export->commit = trace_generic_commit; >> + >> + add_ftrace_export(&ftrace_exports_list, export); >> + >> + mutex_unlock(&ftrace_export_lock); >> + >> + return 0; >> +} >> +EXPORT_SYMBOL_GPL(register_ftrace_export); >> + >> +int unregister_ftrace_export(struct trace_export *export) >> +{ >> + int ret; >> + >> + mutex_lock(&ftrace_export_lock); >> + >> + ret = rm_ftrace_export(&ftrace_exports_list, export); >> + >> + mutex_unlock(&ftrace_export_lock); >> + >> + return ret; >> +} >> +EXPORT_SYMBOL_GPL(unregister_ftrace_export); >> + >> void >> trace_function(struct trace_array *tr, >> unsigned long ip, unsigned long parent_ip, unsigned long flags, >> @@ -2146,8 +2296,11 @@ trace_function(struct trace_array *tr, >> entry->ip = ip; >> entry->parent_ip = parent_ip; >> >> - if (!call_filter_check_discard(call, entry, buffer, event)) >> + if (!call_filter_check_discard(call, entry, buffer, event)) { >> + if (static_branch_unlikely(&ftrace_exports_enabled)) >> + ftrace_exports(tr, event); >> __buffer_unlock_commit(buffer, event); > > We do the generic commit here. > > -- Steve > >> + } >> } >> >> #ifdef CONFIG_STACKTRACE >> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h >> index f783df4..26a3088 100644 >> --- a/kernel/trace/trace.h >> +++ b/kernel/trace/trace.h >> @@ -260,6 +260,7 @@ struct trace_array { >> /* function tracing enabled */ >> int function_enabled; >> #endif >> + struct trace_export *export; >> }; >> >> enum { >
diff --git a/include/linux/trace.h b/include/linux/trace.h new file mode 100644 index 0000000..30ded92 --- /dev/null +++ b/include/linux/trace.h @@ -0,0 +1,35 @@ +#ifndef _LINUX_TRACE_H +#define _LINUX_TRACE_H + +#include <linux/ring_buffer.h> +struct trace_array; + +#ifdef CONFIG_TRACING +/* + * The trace export - an export of Ftrace. The trace_export can process + * traces and export them to a registered destination as an addition to + * the current only output of Ftrace - i.e. ring buffer. + * + * If you want traces to be sent to some other place rather than + * ring buffer only, just need to register a new trace_export and + * implement its own .commit() callback or just directly use + * 'trace_generic_commit()' and hooks up its own .write() function + * for writing traces to the storage. + * + * next - pointer to the next trace_export + * commit - commit the traces to the destination + * write - copy traces which have been delt with ->commit() to + * the destination + */ +struct trace_export { + struct trace_export __rcu *next; + void (*commit)(struct trace_array *, struct ring_buffer_event *); + void (*write)(const char *, unsigned int); +}; + +int register_ftrace_export(struct trace_export *export); +int unregister_ftrace_export(struct trace_export *export); + +#endif /* CONFIG_TRACING */ + +#endif /* _LINUX_TRACE_H */ diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index dade4c9..3163fa6 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -40,6 +40,7 @@ #include <linux/poll.h> #include <linux/nmi.h> #include <linux/fs.h> +#include <linux/trace.h> #include <linux/sched/rt.h> #include "trace.h" @@ -2128,6 +2129,155 @@ void trace_buffer_unlock_commit_regs(struct trace_array *tr, ftrace_trace_userstack(buffer, flags, pc); } +static DEFINE_STATIC_KEY_FALSE(ftrace_exports_enabled); + +static void ftrace_exports_enable(void) +{ + static_branch_enable(&ftrace_exports_enabled); +} + +static void ftrace_exports_disable(void) +{ + static_branch_disable(&ftrace_exports_enabled); +} + +static size_t trace_size[] = { + [TRACE_FN] = sizeof(struct ftrace_entry), + [TRACE_CTX] = sizeof(struct ctx_switch_entry), + [TRACE_WAKE] = sizeof(struct ctx_switch_entry), + [TRACE_STACK] = sizeof(struct stack_entry), + [TRACE_PRINT] = sizeof(struct print_entry), + [TRACE_BPRINT] = sizeof(struct bprint_entry), + [TRACE_MMIO_RW] = sizeof(struct trace_mmiotrace_rw), + [TRACE_MMIO_MAP] = sizeof(struct trace_mmiotrace_map), + [TRACE_BRANCH] = sizeof(struct trace_branch), + [TRACE_GRAPH_RET] = sizeof(struct ftrace_graph_ret_entry), + [TRACE_GRAPH_ENT] = sizeof(struct ftrace_graph_ent_entry), + [TRACE_USER_STACK] = sizeof(struct userstack_entry), + [TRACE_BPUTS] = sizeof(struct bputs_entry), +}; + +static void +trace_generic_commit(struct trace_array *tr, + struct ring_buffer_event *event) +{ + struct trace_entry *entry; + struct trace_export *export = tr->export; + unsigned int size = 0; + + entry = ring_buffer_event_data(event); + + size = trace_size[entry->type]; + if (!size) + return; + + if (export && export->write) + export->write((char *)entry, size); +} + +static DEFINE_MUTEX(ftrace_export_lock); + +static struct trace_export __rcu *ftrace_exports_list __read_mostly; + +static inline void +ftrace_exports(struct trace_array *tr, struct ring_buffer_event *event) +{ + struct trace_export *export; + + preempt_disable_notrace(); + + for (export = rcu_dereference_raw_notrace(ftrace_exports_list); + export && export->commit; + export = rcu_dereference_raw_notrace(export->next)) { + tr->export = export; + export->commit(tr, event); + } + + preempt_enable_notrace(); +} + +static inline void +add_trace_export(struct trace_export **list, struct trace_export *export) +{ + rcu_assign_pointer(export->next, *list); + /* + * We are entering export into the list but another + * CPU might be walking that list. We need to make sure + * the export->next pointer is valid before another CPU sees + * the export pointer included into the list. + */ + rcu_assign_pointer(*list, export); +} + +static inline int +rm_trace_export(struct trace_export **list, struct trace_export *export) +{ + struct trace_export **p; + + for (p = list; *p != NULL; p = &(*p)->next) + if (*p == export) + break; + + if (*p != export) + return -1; + + rcu_assign_pointer(*p, (*p)->next); + + return 0; +} + +static inline void +add_ftrace_export(struct trace_export **list, struct trace_export *export) +{ + if (*list == NULL) + ftrace_exports_enable(); + + add_trace_export(list, export); +} + +static inline int +rm_ftrace_export(struct trace_export **list, struct trace_export *export) +{ + int ret; + + ret = rm_trace_export(list, export); + if (*list == NULL) + ftrace_exports_disable(); + + return ret; +} + +int register_ftrace_export(struct trace_export *export) +{ + if (WARN_ON_ONCE(!export->write)) + return -1; + + mutex_lock(&ftrace_export_lock); + + export->commit = trace_generic_commit; + + add_ftrace_export(&ftrace_exports_list, export); + + mutex_unlock(&ftrace_export_lock); + + return 0; +} +EXPORT_SYMBOL_GPL(register_ftrace_export); + +int unregister_ftrace_export(struct trace_export *export) +{ + int ret; + + mutex_lock(&ftrace_export_lock); + + ret = rm_ftrace_export(&ftrace_exports_list, export); + + mutex_unlock(&ftrace_export_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(unregister_ftrace_export); + void trace_function(struct trace_array *tr, unsigned long ip, unsigned long parent_ip, unsigned long flags, @@ -2146,8 +2296,11 @@ trace_function(struct trace_array *tr, entry->ip = ip; entry->parent_ip = parent_ip; - if (!call_filter_check_discard(call, entry, buffer, event)) + if (!call_filter_check_discard(call, entry, buffer, event)) { + if (static_branch_unlikely(&ftrace_exports_enabled)) + ftrace_exports(tr, event); __buffer_unlock_commit(buffer, event); + } } #ifdef CONFIG_STACKTRACE diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index f783df4..26a3088 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -260,6 +260,7 @@ struct trace_array { /* function tracing enabled */ int function_enabled; #endif + struct trace_export *export; }; enum {
Currently Function traces can be only exported to ring buffer, this patch added trace_export concept which can process traces and export them to a registered destination as an addition to the current only output of Ftrace - i.e. ring buffer. In this way, if we want Function traces to be sent to other destination rather than ring buffer only, we just need to register a new trace_export and implement its own .commit() callback or just use 'trace_generic_commit()' which this patch also added and hooks up its own .write() function for writing traces to the storage. With this patch, only Function trace (trace type is TRACE_FN) is supported. Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org> --- include/linux/trace.h | 35 ++++++++++++ kernel/trace/trace.c | 155 +++++++++++++++++++++++++++++++++++++++++++++++++- kernel/trace/trace.h | 1 + 3 files changed, 190 insertions(+), 1 deletion(-) create mode 100644 include/linux/trace.h -- 2.7.4