linux-toradex.git/include/linux/trace_events.h, branch v4.14-rc7

bpf: one perf event close won't free bpf program attached by another perf event

2017-09-20T21:10:29+00:00

This patch fixes a bug exhibited by the following scenario:
  1. fd1 = perf_event_open with attr.config = ID1
  2. attach bpf program prog1 to fd1
  3. fd2 = perf_event_open with attr.config = ID1
     
  4. user program closes fd2 and prog1 is detached from the tracepoint.
  5. user program with fd1 does not work properly as tracepoint
     no output any more.

The issue happens at step 4. Multiple perf_event_open can be called
successfully, but only one bpf prog pointer in the tp_event. In the
current logic, any fd release for the same tp_event will free
the tp_event->prog.

The fix is to free tp_event->prog only when the closing fd
corresponds to the one which registered the program.

Signed-off-by: Yonghong Song 
Signed-off-by: David S. Miller

Merge tag 'trace-v4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2017-09-08T22:08:14+00:00

Pull tracing updates from Steven Rostedt:
 "Nothing new in development for this release. These are mostly fixes
  that were found during development of changes for the next merge
  window and fixes that were sent to me late in the last cycle"

* tag 'trace-v4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Apply trace_clock changes to instance max buffer
  tracing: Fix clear of RECORDED_TGID flag when disabling trace event
  tracing: Add barrier to trace_printk() buffer nesting modification
  ftrace: Fix memleak when unregistering dynamic ops when tracing disabled
  ftrace: Fix selftest goto location on error
  ftrace: Zero out ftrace hashes when a module is removed
  tracing: Only have rmmod clear buffers that its events were active in
  ftrace: Fix debug preempt config name in stack_tracer_{en,dis}able

tracing: Only have rmmod clear buffers that its events were active in

2017-08-31T21:47:38+00:00

Currently, when a module event is enabled, when that module is removed, it
clears all ring buffers. This is to prevent another module from being loaded
and having one of its trace event IDs from reusing a trace event ID of the
removed module. This could cause undesirable effects as the trace event of
the new module would be using its own processing algorithms to process raw
data of another event. To prevent this, when a module is loaded, if any of
its events have been used (signified by the WAS_ENABLED event call flag,
which is never cleared), all ring buffers are cleared, just in case any one
of them contains event data of the removed event.

The problem is, there's no reason to clear all ring buffers if only one (or
less than all of them) uses one of the events. Instead, only clear the ring
buffers that recorded the events of a module that is being removed.

To do this, instead of keeping the WAS_ENABLED flag with the trace event
call, move it to the per instance (per ring buffer) event file descriptor.
The event file descriptor maps each event to a separate ring buffer
instance. Then when the module is removed, only the ring buffers that
activated one of the module's events get cleared. The rest are not touched.

Signed-off-by: Steven Rostedt (VMware)

perf/ftrace: Fix double traces of perf on ftrace:function

2017-08-29T11:29:29+00:00

When running perf on the ftrace:function tracepoint, there is a bug
which can be reproduced by:

  perf record -e ftrace:function -a sleep 20 &
  perf record -e ftrace:function ls
  perf script

              ls 10304 [005]   171.853235: ftrace:function:
  perf_output_begin
              ls 10304 [005]   171.853237: ftrace:function:
  perf_output_begin
              ls 10304 [005]   171.853239: ftrace:function:
  task_tgid_nr_ns
              ls 10304 [005]   171.853240: ftrace:function:
  task_tgid_nr_ns
              ls 10304 [005]   171.853242: ftrace:function:
  __task_pid_nr_ns
              ls 10304 [005]   171.853244: ftrace:function:
  __task_pid_nr_ns

We can see that all the function traces are doubled.

The problem is caused by the inconsistency of the register
function perf_ftrace_event_register() with the probe function
perf_ftrace_function_call(). The former registers one probe
for every perf_event. And the latter handles all perf_events
on the current cpu. So when two perf_events on the current cpu,
the traces of them will be doubled.

So this patch adds an extra parameter "event" for perf_tp_event,
only send sample data to this event when it's not NULL.

Signed-off-by: Zhou Chengming 
Reviewed-by: Jiri Olsa 
Acked-by: Steven Rostedt (VMware) 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: acme@kernel.org
Cc: alexander.shishkin@linux.intel.com
Cc: huawei.libin@huawei.com
Link: http://lkml.kernel.org/r/1503668977-12526-1-git-send-email-zhouchengming1@huawei.com
Signed-off-by: Ingo Molnar

trace: fix the errors caused by incompatible type of RCU variables

2017-07-20T13:27:29+00:00

The variables which are processed by RCU functions should be annotated
as RCU, otherwise sparse will report the errors like below:

"error: incompatible types in comparison expression (different
address spaces)"

Link: http://lkml.kernel.org/r/1496823171-7758-1-git-send-email-zhang.chunyan@linaro.org

Signed-off-by: Chunyan Zhang 
[ Updated to not be 100% 80 column strict ]
Signed-off-by: Steven Rostedt (VMware)

tracing: Add support for recording tgid of tasks

2017-06-27T17:30:28+00:00

Inorder to support recording of tgid, the following changes are made:

* Introduce a new API (tracing_record_taskinfo) to additionally record the tgid
  along with the task's comm at the same time. This has has the benefit of not
  setting trace_cmdline_save before all the information for a task is saved.
* Add a new API tracing_record_taskinfo_sched_switch to record task information
  for 2 tasks at a time (previous and next) and use it from sched_switch probe.
* Preserve the old API (tracing_record_cmdline) and create it as a wrapper
  around the new one so that existing callers aren't affected.
* Reuse the existing sched_switch and sched_wakeup probes to record tgid
  information and add a new option 'record-tgid' to enable recording of tgid

When record-tgid option isn't enabled to being with, we take care to make sure
that there's isn't memory or runtime overhead.

Link: http://lkml.kernel.org/r/20170627020155.5139-1-joelaf@google.com

Cc: kernel-team@android.com
Cc: Ingo Molnar 
Tested-by: Michael Sartain 
Signed-off-by: Joel Fernandes 
Signed-off-by: Steven Rostedt (VMware)

tracing: Move trace_handle_return() out of line

2017-03-25T00:51:50+00:00

Currently trace_handle_return() looks like this:

 static inline enum print_line_t trace_handle_return(struct trace_seq *s)
 {
        return trace_seq_has_overflowed(s) ?
                TRACE_TYPE_PARTIAL_LINE : TRACE_TYPE_HANDLED;
 }

Where trace_seq_overflowed(s) is:

 static inline bool trace_seq_has_overflowed(struct trace_seq *s)
 {
	return s->full || seq_buf_has_overflowed(&s->seq);
 }

And seq_buf_has_overflowed(&s->seq) is:

 static inline bool
 seq_buf_has_overflowed(struct seq_buf *s)
 {
	return s->len > s->size;
 }

Making trace_handle_return() into:

 return (s->full || (s->seq->len > s->seq->size)) ?
           TRACE_TYPE_PARTIAL_LINE :
           TRACE_TYPE_HANDLED;

One would think this is not an issue to keep as an inline. But because this
is used in the TRACE_EVENT() macro, it is extended for every tracepoint in
the system. Taking a look at a single tracepoint x86_irq_vector (was the
first one I randomly chosen). As trace_handle_return is used in the
TRACE_EVENT() macro of trace_raw_output_##call() we disassemble
trace_raw_output_x86_irq_vector and do a diff:

- is the original
+ is the out-of-line code

I removed identical lines that were different just due to different
addresses.

--- /tmp/irq-vec-orig	2017-03-16 09:12:48.569384851 -0400
+++ /tmp/irq-vec-ool	2017-03-16 09:13:39.378153385 -0400
@@ -6,27 +6,23 @@
        53                      push   %rbx
        48 89 fb                mov    %rdi,%rbx
        4c 8b a7 c0 20 00 00    mov    0x20c0(%rdi),%r12
        e8 f7 72 13 00          callq  ffffffff81155c80 
        83 f8 01                cmp    $0x1,%eax
        74 05                   je     ffffffff8101e993 
        5b                      pop    %rbx
        41 5c                   pop    %r12
        5d                      pop    %rbp
        c3                      retq
        41 8b 54 24 08          mov    0x8(%r12),%edx
-       48 8d bb 98 10 00 00    lea    0x1098(%rbx),%rdi
+       48 81 c3 98 10 00 00    add    $0x1098,%rbx
-       48 c7 c6 7b 8a a0 81    mov    $0xffffffff81a08a7b,%rsi
+       48 c7 c6 ab 8a a0 81    mov    $0xffffffff81a08aab,%rsi
-       e8 c5 85 13 00          callq  ffffffff81156f70 

 === here's the start of the main difference ===

+       48 89 df                mov    %rbx,%rdi
+       e8 62 7e 13 00          callq  ffffffff81156810 
-       8b 93 b8 20 00 00       mov    0x20b8(%rbx),%edx
-       31 c0                   xor    %eax,%eax
-       85 d2                   test   %edx,%edx
-       75 11                   jne    ffffffff8101e9c8 
-       48 8b 83 a8 20 00 00    mov    0x20a8(%rbx),%rax
-       48 39 83 a0 20 00 00    cmp    %rax,0x20a0(%rbx)
-       0f 93 c0                setae  %al
+       48 89 df                mov    %rbx,%rdi
+       e8 4a c5 12 00          callq  ffffffff8114af00 
        5b                      pop    %rbx
-       0f b6 c0                movzbl %al,%eax

 === end ===

        41 5c                   pop    %r12
        5d                      pop    %rbp
        c3                      retq

If you notice, the original has 22 bytes of text more than the out of line
version. As this is for every TRACE_EVENT() defined in the system, this can
become quite large.

   text	   data	    bss	    dec	    hex	filename
8690305	5450490	1298432	15439227	 eb957b	vmlinux-orig
8681725	5450490	1298432	15430647	 eb73f7	vmlinux-handle

This change has a total of 8580 bytes in savings.

 $ objdump -dr /tmp/vmlinux-orig | grep '^[0-9a-f]* 
Signed-off-by: Steven Rostedt (VMware)

tracing: add __print_flags_u64()

2017-02-23T00:41:26+00:00

Patch series "DAX tracepoints, mm argument simplification", v4.

This contains both my DAX tracepoint code and Dave Jiang's MM argument
simplifications.  Dave's code was written with my tracepoint code as a
baseline, so it seemed simplest to keep them together in a single series.

This patch (of 7):

Add __print_flags_u64() and the helper trace_print_flags_seq_u64() in the
same spirit as __print_symbolic_u64() and trace_print_symbols_seq_u64().
These functions allow us to print symbols associated with flags that are
64 bits wide even on 32 bit machines.

These will be used by the DAX code so that we can print the flags set in a
pfn_t such as PFN_SG_CHAIN, PFN_SG_LAST, PFN_DEV and PFN_MAP.

Without this new function I was getting errors like the following when
compiling for i386:

  include/linux/pfn_t.h:13:22: warning: large integer implicitly truncated to unsigned type [-Woverflow]
   #define PFN_SG_CHAIN (1ULL << (BITS_PER_LONG_LONG - 1))
    ^

Link: http://lkml.kernel.org/r/1484085142-2297-2-git-send-email-ross.zwisler@linux.intel.com
Signed-off-by: Ross Zwisler 
Reviewed-by: Steven Rostedt 
Cc: Dave Chinner 
Cc: Dave Jiang 
Cc: Jan Kara 
Cc: Matthew Wilcox 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

trace: rename trace_print_hex_seq arg and add kdoc

2017-02-03T20:50:18+00:00

Steven suggested to improve trace_print_hex_seq() a bit after commit
2acae0d5b0f7 ("trace: add variant without spacing in trace_print_hex_seq")
in two ways: i) by adding a kdoc comment for the helper function
itself and ii) by renaming 'spacing' argument into 'concatenate'
to better denote that we don't add spaces between each hex bytes.

Suggested-by: Steven Rostedt 
Signed-off-by: Daniel Borkmann 
Signed-off-by: David S. Miller

trace: add variant without spacing in trace_print_hex_seq

2017-01-25T18:17:47+00:00

For upcoming tracepoint support for BPF, we want to dump the program's
tag. Format should be similar to __print_hex(), but without spacing.
Add a __print_hex_str() variant for exactly that purpose that reuses
trace_print_hex_seq().

Signed-off-by: Daniel Borkmann 
Cc: Steven Rostedt 
Cc: Arnaldo Carvalho de Melo 
Signed-off-by: David S. Miller