From a9c4bdd505630469f93f5efedfc7a9ca254996c8 Mon Sep 17 00:00:00 2001 From: Linyu Yuan Date: Mon, 30 Jan 2023 15:54:09 +0800 Subject: tracing: Acquire buffer from temparary trace sequence there is one dwc3 trace event declare as below, DECLARE_EVENT_CLASS(dwc3_log_event, TP_PROTO(u32 event, struct dwc3 *dwc), TP_ARGS(event, dwc), TP_STRUCT__entry( __field(u32, event) __field(u32, ep0state) __dynamic_array(char, str, DWC3_MSG_MAX) ), TP_fast_assign( __entry->event = event; __entry->ep0state = dwc->ep0state; ), TP_printk("event (%08x): %s", __entry->event, dwc3_decode_event(__get_str(str), DWC3_MSG_MAX, __entry->event, __entry->ep0state)) ); the problem is when trace function called, it will allocate up to DWC3_MSG_MAX bytes from trace event buffer, but never fill the buffer during fast assignment, it only fill the buffer when output function are called, so this means if output function are not called, the buffer will never used. add __get_buf(len) which acquiree buffer from iter->tmp_seq when trace output function called, it allow user write string to acquired buffer. the mentioned dwc3 trace event will changed as below, DECLARE_EVENT_CLASS(dwc3_log_event, TP_PROTO(u32 event, struct dwc3 *dwc), TP_ARGS(event, dwc), TP_STRUCT__entry( __field(u32, event) __field(u32, ep0state) ), TP_fast_assign( __entry->event = event; __entry->ep0state = dwc->ep0state; ), TP_printk("event (%08x): %s", __entry->event, dwc3_decode_event(__get_buf(DWC3_MSG_MAX), DWC3_MSG_MAX, __entry->event, __entry->ep0state)) );. Link: https://lore.kernel.org/linux-trace-kernel/1675065249-23368-1-git-send-email-quic_linyyuan@quicinc.com Cc: Masami Hiramatsu Signed-off-by: Linyu Yuan Signed-off-by: Steven Rostedt (Google) --- include/linux/trace_seq.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux') diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h index 0c4c7587d6c3..6be92bf559fe 100644 --- a/include/linux/trace_seq.h +++ b/include/linux/trace_seq.h @@ -95,6 +95,7 @@ extern void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp, extern int trace_seq_hex_dump(struct trace_seq *s, const char *prefix_str, int prefix_type, int rowsize, int groupsize, const void *buf, size_t len, bool ascii); +char *trace_seq_acquire(struct trace_seq *s, unsigned int len); #else /* CONFIG_TRACING */ static inline __printf(2, 3) @@ -139,6 +140,10 @@ static inline int trace_seq_path(struct trace_seq *s, const struct path *path) { return 0; } +static inline char *trace_seq_acquire(struct trace_seq *s, unsigned int len) +{ + return NULL; +} #endif /* CONFIG_TRACING */ #endif /* _LINUX_TRACE_SEQ_H */ -- cgit v1.2.3 From d503b8f7474fe7ac616518f7fc49773cbab49f36 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Tue, 7 Feb 2023 12:28:52 -0500 Subject: tracing: Add trace_array_puts() to write into instance Add a generic trace_array_puts() that can be used to "trace_puts()" into an allocated trace_array instance. This is just another variant of trace_array_printk(). Link: https://lkml.kernel.org/r/20230207173026.584717290@goodmis.org Cc: Masami Hiramatsu Cc: Andrew Morton Reviewed-by: Ross Zwisler Signed-off-by: Steven Rostedt (Google) --- include/linux/trace.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'include/linux') diff --git a/include/linux/trace.h b/include/linux/trace.h index 80ffda871749..2a70a447184c 100644 --- a/include/linux/trace.h +++ b/include/linux/trace.h @@ -33,6 +33,18 @@ struct trace_array; int register_ftrace_export(struct trace_export *export); int unregister_ftrace_export(struct trace_export *export); +/** + * trace_array_puts - write a constant string into the trace buffer. + * @tr: The trace array to write to + * @str: The constant string to write + */ +#define trace_array_puts(tr, str) \ + ({ \ + str ? __trace_array_puts(tr, _THIS_IP_, str, strlen(str)) : -1; \ + }) +int __trace_array_puts(struct trace_array *tr, unsigned long ip, + const char *str, int size); + void trace_printk_init_buffers(void); __printf(3, 4) int trace_array_printk(struct trace_array *tr, unsigned long ip, -- cgit v1.2.3 From 2455f0e124d317dd08d337a7550a78a224d4ba41 Mon Sep 17 00:00:00 2001 From: Ross Zwisler Date: Wed, 15 Feb 2023 15:33:45 -0700 Subject: tracing: Always use canonical ftrace path The canonical location for the tracefs filesystem is at /sys/kernel/tracing. But, from Documentation/trace/ftrace.rst: Before 4.1, all ftrace tracing control files were within the debugfs file system, which is typically located at /sys/kernel/debug/tracing. For backward compatibility, when mounting the debugfs file system, the tracefs file system will be automatically mounted at: /sys/kernel/debug/tracing Many comments and Kconfig help messages in the tracing code still refer to this older debugfs path, so let's update them to avoid confusion. Link: https://lore.kernel.org/linux-trace-kernel/20230215223350.2658616-2-zwisler@google.com Acked-by: Masami Hiramatsu (Google) Reviewed-by: Mukesh Ojha Signed-off-by: Ross Zwisler Signed-off-by: Steven Rostedt (Google) --- include/linux/kernel.h | 2 +- include/linux/tracepoint.h | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) (limited to 'include/linux') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index fe6efb24d151..40bce7495af8 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -297,7 +297,7 @@ bool mac_pton(const char *s, u8 *mac); * * Use tracing_on/tracing_off when you want to quickly turn on or off * tracing. It simply enables or disables the recording of the trace events. - * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on + * This also corresponds to the user space /sys/kernel/tracing/tracing_on * file, which gives a means for the kernel and userspace to interact. * Place a tracing_off() in the kernel where you want tracing to end. * From user space, examine the trace, and then echo 1 > tracing_on diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 4b33b95eb8be..fa1004fcf810 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -471,7 +471,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) * * This is how the trace record is structured and will * * be saved into the ring buffer. These are the fields * * that will be exposed to user-space in - * * /sys/kernel/debug/tracing/events/<*>/format. + * * /sys/kernel/tracing/events/<*>/format. * * * * The declared 'local variable' is called '__entry' * * @@ -531,7 +531,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) * tracepoint callback (this is used by programmatic plugins and * can also by used by generic instrumentation like SystemTap), and * it is also used to expose a structured trace record in - * /sys/kernel/debug/tracing/events/. + * /sys/kernel/tracing/events/. * * A set of (un)registration functions can be passed to the variant * TRACE_EVENT_FN to perform any (un)registration work. -- cgit v1.2.3