Merge branch 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (44 commits)
  vsnprintf: remove duplicate comment of vsnprintf
  softirq: add BLOCK_IOPOLL to softirq_to_name
  oprofile: fix oprofile regression: select RING_BUFFER_ALLOW_SWAP
  tracing: switch function prints from %pf to %ps
  vsprintf: add %ps that is the same as %pS but is like %pf
  tracing: Fix minor bugs for __unregister_ftrace_function_probe
  tracing: remove notrace from __kprobes annotation
  tracing: optimize global_trace_clock cachelines
  MAINTAINERS: Update tracing tree details
  ftrace: document function and function graph implementation
  tracing: make testing syscall events a separate configuration
  tracing: remove some unused macros
  ftrace: add compile-time check on F_printk()
  tracing: fix F_printk() typos
  tracing: have TRACE_EVENT macro use __flags to not shadow parameter
  tracing: add static to generated TRACE_EVENT functions
  ring-buffer: typecast cmpxchg to fix PowerPC warning
  tracing: add filter event logic to special, mmiotrace and boot tracers
  tracing: remove trace_event_types.h
  tracing: use the new trace_entries.h to create format files
  ...

3 files changed, 422 insertions, 1 deletions

diff --git a/Documentation/trace/events.txt b/Documentation/trace/events.txt
index 90e8b3383ba2..78c45a87be57 100644
--- a/Documentation/trace/events.txt
+++ b/Documentation/trace/events.txt
@@ -1,7 +1,7 @@
                              Event Tracing
 
                 Documentation written by Theodore Ts'o
-                        Updated by Li Zefan
+                Updated by Li Zefan and Tom Zanussi
 
 1. Introduction
 ===============
@@ -97,3 +97,185 @@ The format of this boot option is the same as described in section 2.1.
 
 See The example provided in samples/trace_events
 
+4. Event formats
+================
+
+Each trace event has a 'format' file associated with it that contains
+a description of each field in a logged event.  This information can
+be used to parse the binary trace stream, and is also the place to
+find the field names that can be used in event filters (see section 5).
+
+It also displays the format string that will be used to print the
+event in text mode, along with the event name and ID used for
+profiling.
+
+Every event has a set of 'common' fields associated with it; these are
+the fields prefixed with 'common_'.  The other fields vary between
+events and correspond to the fields defined in the TRACE_EVENT
+definition for that event.
+
+Each field in the format has the form:
+
+     field:field-type field-name; offset:N; size:N;
+
+where offset is the offset of the field in the trace record and size
+is the size of the data item, in bytes.
+
+For example, here's the information displayed for the 'sched_wakeup'
+event:
+
+# cat /debug/tracing/events/sched/sched_wakeup/format
+
+name: sched_wakeup
+ID: 60
+format:
+        field:unsigned short common_type;       offset:0;       size:2;
+        field:unsigned char common_flags;       offset:2;       size:1;
+        field:unsigned char common_preempt_count;       offset:3;       size:1;
+        field:int common_pid;   offset:4;       size:4;
+        field:int common_tgid;  offset:8;       size:4;
+
+        field:char comm[TASK_COMM_LEN]; offset:12;      size:16;
+        field:pid_t pid;        offset:28;      size:4;
+        field:int prio; offset:32;      size:4;
+        field:int success;      offset:36;      size:4;
+        field:int cpu;  offset:40;      size:4;
+
+print fmt: "task %s:%d [%d] success=%d [%03d]", REC->comm, REC->pid,
+           REC->prio, REC->success, REC->cpu
+
+This event contains 10 fields, the first 5 common and the remaining 5
+event-specific.  All the fields for this event are numeric, except for
+'comm' which is a string, a distinction important for event filtering.
+
+5. Event filtering
+==================
+
+Trace events can be filtered in the kernel by associating boolean
+'filter expressions' with them.  As soon as an event is logged into
+the trace buffer, its fields are checked against the filter expression
+associated with that event type.  An event with field values that
+'match' the filter will appear in the trace output, and an event whose
+values don't match will be discarded.  An event with no filter
+associated with it matches everything, and is the default when no
+filter has been set for an event.
+
+5.1 Expression syntax
+---------------------
+
+A filter expression consists of one or more 'predicates' that can be
+combined using the logical operators '&&' and '||'.  A predicate is
+simply a clause that compares the value of a field contained within a
+logged event with a constant value and returns either 0 or 1 depending
+on whether the field value matched (1) or didn't match (0):
+
+          field-name relational-operator value
+
+Parentheses can be used to provide arbitrary logical groupings and
+double-quotes can be used to prevent the shell from interpreting
+operators as shell metacharacters.
+
+The field-names available for use in filters can be found in the
+'format' files for trace events (see section 4).
+
+The relational-operators depend on the type of the field being tested:
+
+The operators available for numeric fields are:
+
+==, !=, <, <=, >, >=
+
+And for string fields they are:
+
+==, !=
+
+Currently, only exact string matches are supported.
+
+Currently, the maximum number of predicates in a filter is 16.
+
+5.2 Setting filters
+-------------------
+
+A filter for an individual event is set by writing a filter expression
+to the 'filter' file for the given event.
+
+For example:
+
+# cd /debug/tracing/events/sched/sched_wakeup
+# echo "common_preempt_count > 4" > filter
+
+A slightly more involved example:
+
+# cd /debug/tracing/events/sched/sched_signal_send
+# echo "((sig >= 10 && sig < 15) || sig == 17) && comm != bash" > filter
+
+If there is an error in the expression, you'll get an 'Invalid
+argument' error when setting it, and the erroneous string along with
+an error message can be seen by looking at the filter e.g.:
+
+# cd /debug/tracing/events/sched/sched_signal_send
+# echo "((sig >= 10 && sig < 15) || dsig == 17) && comm != bash" > filter
+-bash: echo: write error: Invalid argument
+# cat filter
+((sig >= 10 && sig < 15) || dsig == 17) && comm != bash
+^
+parse_error: Field not found
+
+Currently the caret ('^') for an error always appears at the beginning of
+the filter string; the error message should still be useful though
+even without more accurate position info.
+
+5.3 Clearing filters
+--------------------
+
+To clear the filter for an event, write a '0' to the event's filter
+file.
+
+To clear the filters for all events in a subsystem, write a '0' to the
+subsystem's filter file.
+
+5.3 Subsystem filters
+---------------------
+
+For convenience, filters for every event in a subsystem can be set or
+cleared as a group by writing a filter expression into the filter file
+at the root of the subsytem.  Note however, that if a filter for any
+event within the subsystem lacks a field specified in the subsystem
+filter, or if the filter can't be applied for any other reason, the
+filter for that event will retain its previous setting.  This can
+result in an unintended mixture of filters which could lead to
+confusing (to the user who might think different filters are in
+effect) trace output.  Only filters that reference just the common
+fields can be guaranteed to propagate successfully to all events.
+
+Here are a few subsystem filter examples that also illustrate the
+above points:
+
+Clear the filters on all events in the sched subsytem:
+
+# cd /sys/kernel/debug/tracing/events/sched
+# echo 0 > filter
+# cat sched_switch/filter
+none
+# cat sched_wakeup/filter
+none
+
+Set a filter using only common fields for all events in the sched
+subsytem (all events end up with the same filter):
+
+# cd /sys/kernel/debug/tracing/events/sched
+# echo common_pid == 0 > filter
+# cat sched_switch/filter
+common_pid == 0
+# cat sched_wakeup/filter
+common_pid == 0
+
+Attempt to set a filter using a non-common field for all events in the
+sched subsytem (all events but those that have a prev_pid field retain
+their old filters):
+
+# cd /sys/kernel/debug/tracing/events/sched
+# echo prev_pid == 0 > filter
+# cat sched_switch/filter
+prev_pid == 0
+# cat sched_wakeup/filter
+common_pid == 0
diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
new file mode 100644
index 000000000000..7003e10f10f5
--- /dev/null
+++ b/Documentation/trace/ftrace-design.txt
@@ -0,0 +1,233 @@
+                function tracer guts
+                ====================
+
+Introduction
+------------
+
+Here we will cover the architecture pieces that the common function tracing
+code relies on for proper functioning.  Things are broken down into increasing
+complexity so that you can start simple and at least get basic functionality.
+
+Note that this focuses on architecture implementation details only.  If you
+want more explanation of a feature in terms of common code, review the common
+ftrace.txt file.
+
+
+Prerequisites
+-------------
+
+Ftrace relies on these features being implemented:
+ STACKTRACE_SUPPORT - implement save_stack_trace()
+ TRACE_IRQFLAGS_SUPPORT - implement include/asm/irqflags.h
+
+
+HAVE_FUNCTION_TRACER
+--------------------
+
+You will need to implement the mcount and the ftrace_stub functions.
+
+The exact mcount symbol name will depend on your toolchain.  Some call it
+"mcount", "_mcount", or even "__mcount".  You can probably figure it out by
+running something like:
+        $ echo 'main(){}' | gcc -x c -S -o - - -pg | grep mcount
+                call    mcount
+We'll make the assumption below that the symbol is "mcount" just to keep things
+nice and simple in the examples.
+
+Keep in mind that the ABI that is in effect inside of the mcount function is
+*highly* architecture/toolchain specific.  We cannot help you in this regard,
+sorry.  Dig up some old documentation and/or find someone more familiar than
+you to bang ideas off of.  Typically, register usage (argument/scratch/etc...)
+is a major issue at this point, especially in relation to the location of the
+mcount call (before/after function prologue).  You might also want to look at
+how glibc has implemented the mcount function for your architecture.  It might
+be (semi-)relevant.
+
+The mcount function should check the function pointer ftrace_trace_function
+to see if it is set to ftrace_stub.  If it is, there is nothing for you to do,
+so return immediately.  If it isn't, then call that function in the same way
+the mcount function normally calls __mcount_internal -- the first argument is
+the "frompc" while the second argument is the "selfpc" (adjusted to remove the
+size of the mcount call that is embedded in the function).
+
+For example, if the function foo() calls bar(), when the bar() function calls
+mcount(), the arguments mcount() will pass to the tracer are:
+        "frompc" - the address bar() will use to return to foo()
+        "selfpc" - the address bar() (with _mcount() size adjustment)
+
+Also keep in mind that this mcount function will be called *a lot*, so
+optimizing for the default case of no tracer will help the smooth running of
+your system when tracing is disabled.  So the start of the mcount function is
+typically the bare min with checking things before returning.  That also means
+the code flow should usually kept linear (i.e. no branching in the nop case).
+This is of course an optimization and not a hard requirement.
+
+Here is some pseudo code that should help (these functions should actually be
+implemented in assembly):
+
+void ftrace_stub(void)
+{
+        return;
+}
+
+void mcount(void)
+{
+        /* save any bare state needed in order to do initial checking */
+
+        extern void (*ftrace_trace_function)(unsigned long, unsigned long);
+        if (ftrace_trace_function != ftrace_stub)
+                goto do_trace;
+
+        /* restore any bare state */
+
+        return;
+
+do_trace:
+
+        /* save all state needed by the ABI (see paragraph above) */
+
+        unsigned long frompc = ...;
+        unsigned long selfpc = <return address> - MCOUNT_INSN_SIZE;
+        ftrace_trace_function(frompc, selfpc);
+
+        /* restore all state needed by the ABI */
+}
+
+Don't forget to export mcount for modules !
+extern void mcount(void);
+EXPORT_SYMBOL(mcount);
+
+
+HAVE_FUNCTION_TRACE_MCOUNT_TEST
+-------------------------------
+
+This is an optional optimization for the normal case when tracing is turned off
+in the system.  If you do not enable this Kconfig option, the common ftrace
+code will take care of doing the checking for you.
+
+To support this feature, you only need to check the function_trace_stop
+variable in the mcount function.  If it is non-zero, there is no tracing to be
+done at all, so you can return.
+
+This additional pseudo code would simply be:
+void mcount(void)
+{
+        /* save any bare state needed in order to do initial checking */
+
++       if (function_trace_stop)
++               return;
+
+        extern void (*ftrace_trace_function)(unsigned long, unsigned long);
+        if (ftrace_trace_function != ftrace_stub)
+...
+
+
+HAVE_FUNCTION_GRAPH_TRACER
+--------------------------
+
+Deep breath ... time to do some real work.  Here you will need to update the
+mcount function to check ftrace graph function pointers, as well as implement
+some functions to save (hijack) and restore the return address.
+
+The mcount function should check the function pointers ftrace_graph_return
+(compare to ftrace_stub) and ftrace_graph_entry (compare to
+ftrace_graph_entry_stub).  If either of those are not set to the relevant stub
+function, call the arch-specific function ftrace_graph_caller which in turn
+calls the arch-specific function prepare_ftrace_return.  Neither of these
+function names are strictly required, but you should use them anyways to stay
+consistent across the architecture ports -- easier to compare & contrast
+things.
+
+The arguments to prepare_ftrace_return are slightly different than what are
+passed to ftrace_trace_function.  The second argument "selfpc" is the same,
+but the first argument should be a pointer to the "frompc".  Typically this is
+located on the stack.  This allows the function to hijack the return address
+temporarily to have it point to the arch-specific function return_to_handler.
+That function will simply call the common ftrace_return_to_handler function and
+that will return the original return address with which, you can return to the
+original call site.
+
+Here is the updated mcount pseudo code:
+void mcount(void)
+{
+...
+        if (ftrace_trace_function != ftrace_stub)
+                goto do_trace;
+
++#ifdef CONFIG_FUNCTION_GRAPH_TRACER
++       extern void (*ftrace_graph_return)(...);
++       extern void (*ftrace_graph_entry)(...);
++       if (ftrace_graph_return != ftrace_stub ||
++           ftrace_graph_entry != ftrace_graph_entry_stub)
++               ftrace_graph_caller();
++#endif
+
+        /* restore any bare state */
+...
+
+Here is the pseudo code for the new ftrace_graph_caller assembly function:
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+void ftrace_graph_caller(void)
+{
+        /* save all state needed by the ABI */
+
+        unsigned long *frompc = &...;
+        unsigned long selfpc = <return address> - MCOUNT_INSN_SIZE;
+        prepare_ftrace_return(frompc, selfpc);
+
+        /* restore all state needed by the ABI */
+}
+#endif
+
+For information on how to implement prepare_ftrace_return(), simply look at
+the x86 version.  The only architecture-specific piece in it is the setup of
+the fault recovery table (the asm(...) code).  The rest should be the same
+across architectures.
+
+Here is the pseudo code for the new return_to_handler assembly function.  Note
+that the ABI that applies here is different from what applies to the mcount
+code.  Since you are returning from a function (after the epilogue), you might
+be able to skimp on things saved/restored (usually just registers used to pass
+return values).
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+void return_to_handler(void)
+{
+        /* save all state needed by the ABI (see paragraph above) */
+
+        void (*original_return_point)(void) = ftrace_return_to_handler();
+
+        /* restore all state needed by the ABI */
+
+        /* this is usually either a return or a jump */
+        original_return_point();
+}
+#endif
+
+
+HAVE_FTRACE_NMI_ENTER
+---------------------
+
+If you can't trace NMI functions, then skip this option.
+
+<details to be filled>
+
+
+HAVE_FTRACE_SYSCALLS
+---------------------
+
+<details to be filled>
+
+
+HAVE_FTRACE_MCOUNT_RECORD
+-------------------------
+
+See scripts/recordmcount.pl for more info.
+
+<details to be filled>
+
+
+HAVE_DYNAMIC_FTRACE
+---------------------
+
+<details to be filled>
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 355d0f1f8c50..1b6292bbdd6d 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -26,6 +26,12 @@ disabled, and more (ftrace allows for tracer plugins, which
 means that the list of tracers can always grow).
 
 
+Implementation Details
+----------------------
+
+See ftrace-design.txt for details for arch porters and such.
+
+
 The File System
 ---------------