kernel/include/trace/ftrace.h, branch linux-4.15.y

tracing: Rename trace/ftrace.h to trace/trace_events.h

2015-05-13T18:05:05Z

The name "ftrace" really refers to the function hook infrastructure. It is not about the TRACE_EVENT() macros. The file trace/ftrace.h was originally written to be mostly focused toward the "ftrace" code (that in kernel/trace/) but ended up being generic and used by perf and others. Rename the file to be less confusing about what infrastructure it belongs to. Signed-off-by: Steven Rostedt

tracing: Add TRACE_DEFINE_ENUM() macro to map enums to their values

2015-04-08T13:39:56Z

Several tracepoints use the helper functions __print_symbolic() or __print_flags() and pass in enums that do the mapping between the binary data stored and the value to print. This works well for reading the ASCII trace files, but when the data is read via userspace tools such as perf and trace-cmd, the conversion of the binary value to a human string format is lost if an enum is used, as userspace does not have access to what the ENUM is. For example, the tracepoint trace_tlb_flush() has: __print_symbolic(REC->reason, { TLB_FLUSH_ON_TASK_SWITCH, "flush on task switch" }, { TLB_REMOTE_SHOOTDOWN, "remote shootdown" }, { TLB_LOCAL_SHOOTDOWN, "local shootdown" }, { TLB_LOCAL_MM_SHOOTDOWN, "local mm shootdown" }) Which maps the enum values to the strings they represent. But perf and trace-cmd do no know what value TLB_LOCAL_MM_SHOOTDOWN is, and would not be able to map it. With TRACE_DEFINE_ENUM(), developers can place these in the event header files and ftrace will convert the enums to their values: By adding: TRACE_DEFINE_ENUM(TLB_FLUSH_ON_TASK_SWITCH); TRACE_DEFINE_ENUM(TLB_REMOTE_SHOOTDOWN); TRACE_DEFINE_ENUM(TLB_LOCAL_SHOOTDOWN); TRACE_DEFINE_ENUM(TLB_LOCAL_MM_SHOOTDOWN); $ cat /sys/kernel/debug/tracing/events/tlb/tlb_flush/format [...] __print_symbolic(REC->reason, { 0, "flush on task switch" }, { 1, "remote shootdown" }, { 2, "local shootdown" }, { 3, "local mm shootdown" }) The above is what userspace expects to see, and tools do not need to be modified to parse them. Link: http://lkml.kernel.org/r/20150403013802.220157513@goodmis.org Cc: Guilherme Cox Cc: Tony Luck Cc: Xie XiuQi Acked-by: Namhyung Kim Reviewed-by: Masami Hiramatsu Tested-by: Masami Hiramatsu Signed-off-by: Steven Rostedt

tracing: Give system name a pointer

2015-04-08T13:39:55Z

Normally the compiler will use the same pointer for a string throughout the file. But there's no guarantee of that happening. Later changes will require that all events have the same pointer to the system string. Name the system string and have all events point to it. Testing this, it did not increases the size of the text, except for the notes section, which should not harm the real size any. Link: http://lkml.kernel.org/r/20150403013802.220157513@goodmis.org Reviewed-by: Masami Hiramatsu Tested-by: Masami Hiramatsu Signed-off-by: Steven Rostedt

Merge tag 'trace-v3.20' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2015-02-12T16:37:41Z

Pull tracing updates from Steven Rostedt: "The updates included in this pull request for ftrace are: o Several clean ups to the code One such clean up was to convert to 64 bit time keeping, in the ring buffer benchmark code. o Adding of __print_array() helper macro for TRACE_EVENT() o Updating the sample/trace_events/ to add samples of different ways to make trace events. Lots of features have been added since the sample code was made, and these features are mostly unknown. Developers have been making their own hacks to do things that are already available. o Performance improvements. Most notably, I found a performance bug where a waiter that is waiting for a full page from the ring buffer will see that a full page is not available, and go to sleep. The sched event caused by it going to sleep would cause it to wake up again. It would see that there was still not a full page, and go back to sleep again, and that would wake it up again, until finally it would see a full page. This change has been marked for stable. Other improvements include removing global locks from fast paths" * tag 'trace-v3.20' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: ring-buffer: Do not wake up a splice waiter when page is not full tracing: Fix unmapping loop in tracing_mark_write tracing: Add samples of DECLARE_EVENT_CLASS() and DEFINE_EVENT() tracing: Add TRACE_EVENT_FN example tracing: Add TRACE_EVENT_CONDITION sample tracing: Update the TRACE_EVENT fields available in the sample code tracing: Separate out initializing top level dir from instances tracing: Make tracing_init_dentry_tr() static trace: Use 64-bit timekeeping tracing: Add array printing helper tracing: Remove newline from trace_printk warning banner tracing: Use IS_ERR() check for return value of tracing_init_dentry() tracing: Remove unneeded includes of debugfs.h and fs.h tracing: Remove taking of trace_types_lock in pipe files tracing: Add ref count to tracer for when they are being read by pipe

tracing: Add array printing helper

2015-01-28T15:34:47Z

If a trace event contains an array, there is currently no standard way to format this for text output. Drivers are currently hacking around this by a) local hacks that use the trace_seq functionailty directly, or b) just not printing that information. For fixed size arrays, formatting of the elements can be open-coded, but this gets cumbersome for arrays of non-trivial size. These approaches result in non-standard content of the event format description delivered to userspace, so userland tools needs to be taught to understand and parse each array printing method individually. This patch implements a __print_array() helper that tracepoint implementations can use instead of reinventing it. A simple C-style syntax is used to delimit the array and its elements {like,this}. So that the helpers can be used with large static arrays as well as dynamic arrays, they take a pointer and element count: they can be used with __get_dynamic_array() for use with dynamic arrays. Link: http://lkml.kernel.org/r/1422449335-8289-2-git-send-email-javi.merino@arm.com Cc: Ingo Molnar Signed-off-by: Dave Martin Signed-off-by: Javi Merino Signed-off-by: Steven Rostedt

perf: Avoid horrible stack usage

2015-01-14T14:11:45Z

Both Linus (most recent) and Steve (a while ago) reported that perf related callbacks have massive stack bloat. The problem is that software events need a pt_regs in order to properly report the event location and unwind stack. And because we could not assume one was present we allocated one on stack and filled it with minimal bits required for operation. Now, pt_regs is quite large, so this is undesirable. Furthermore it turns out that most sites actually have a pt_regs pointer available, making this even more onerous, as the stack space is pointless waste. This patch addresses the problem by observing that software events have well defined nesting semantics, therefore we can use static per-cpu storage instead of on-stack. Linus made the further observation that all but the scheduler callers of perf_sw_event() have a pt_regs available, so we change the regular perf_sw_event() to require a valid pt_regs (where it used to be optional) and add perf_sw_event_sched() for the scheduler. We have a scheduler specific call instead of a more generic _noregs() like construct because we can assume non-recursion from the scheduler and thereby simplify the code further (_noregs would have to put the recursion context call inline in order to assertain which __perf_regs element to use). One last note on the implementation of perf_trace_buf_prepare(); we allow .regs = NULL for those cases where we already have a pt_regs pointer available and do not need another. Reported-by: Linus Torvalds Reported-by: Steven Rostedt Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Javi Merino Cc: Linus Torvalds Cc: Mathieu Desnoyers Cc: Oleg Nesterov Cc: Paul Mackerras Cc: Petr Mladek Cc: Steven Rostedt Cc: Tom Zanussi Cc: Vaibhav Nagarnaik Link: http://lkml.kernel.org/r/20141216115041.GW3337@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar

tracing: Fix return value of ftrace_raw_output_prep()

2014-11-19T20:25:48Z

If the trace_seq of ftrace_raw_output_prep() is full this function returns TRACE_TYPE_PARTIAL_LINE, otherwise it returns zero. The problem is that TRACE_TYPE_PARTIAL_LINE happens to be zero! The thing is, the caller of ftrace_raw_output_prep() expects a success to be zero. Change that to expect it to be TRACE_TYPE_HANDLED. Link: http://lkml.kernel.org/r/20141114112522.GA2988@dhcp128.suse.cz Reminded-by: Petr Mladek Signed-off-by: Steven Rostedt

tracing: Add trace_seq_has_overflowed() and trace_handle_return()

2014-11-19T20:25:39Z

Adding a trace_seq_has_overflowed() which returns true if the trace_seq had too much written into it allows us to simplify the code. Instead of checking the return value of every call to trace_seq_printf() and friends, they can all be called normally, and at the end we can return !trace_seq_has_overflowed() instead. Several functions also return TRACE_TYPE_PARTIAL_LINE when the trace_seq overflowed and TRACE_TYPE_HANDLED otherwise. Another helper function was created called trace_handle_return() which takes a trace_seq and returns these enums. Using this helper function also simplifies the code. This change also makes it possible to remove the return values of trace_seq_printf() and friends. They should instead just be void functions. Link: http://lkml.kernel.org/r/20141114011410.365183157@goodmis.org Reviewed-by: Petr Mladek Signed-off-by: Steven Rostedt

tracing: Add __field_struct macro for TRACE_EVENT()

2014-06-21T04:18:42Z

Currently the __field() macro in TRACE_EVENT is only good for primitive values, such as integers and pointers, but it fails on complex data types such as structures or unions. This is because the __field() macro determines if the variable is signed or not with the test of: (((type)(-1)) < (type)1) Unfortunately, that fails when type is a structure. Since trace events should support structures as fields a new macro is created for such a case called __field_struct() which acts exactly the same as __field() does but it does not do the signed type check and just uses a constant false for that answer. Cc: Tony Luck Signed-off-by: Steven Rostedt

tracing: Add __get_dynamic_array_len() macro for trace events

2014-06-04T18:29:33Z

If a trace event uses a dynamic array for something other than a string then there's currently no way the TP_printk() can figure out what size it is. A __get_dynamic_array_len() is required to know the length. This also simplifies the __get_bitmask() macro which required it as well, but instead just hardcoded it. Signed-off-by: Steven Rostedt