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Commit f8effd1a authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'tracing-fixes-for-linus' of... 

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

* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  doc: mmiotrace.txt, buffer size control change
  trace: mmiotrace to the tracer menu in Kconfig
  mmiotrace: count events lost due to not recording
parents 35010334 f9aa28ad

Documentation/tracers/mmiotrace.txt

+2 −4
Original line number Diff line number Diff line
@@ -78,12 +78,10 @@ to view your kernel log and look for "mmiotrace has lost events" warning. If 
events were lost, the trace is incomplete. You should enlarge the buffers and

try again. Buffers are enlarged by first seeing how large the current buffers

are:

$ cat /debug/tracing/trace_entries

$ cat /debug/tracing/buffer_size_kb

gives you a number. Approximately double this number and write it back, for

instance:

$ echo 0 > /debug/tracing/tracing_enabled

$ echo 128000 > /debug/tracing/trace_entries

$ echo 1 > /debug/tracing/tracing_enabled

$ echo 128000 > /debug/tracing/buffer_size_kb

Then start again from the top.



If you are doing a trace for a driver project, e.g. Nouveau, you should also

arch/x86/Kconfig.debug

+2 −22
Original line number Diff line number Diff line
@@ -174,28 +174,8 @@ config IOMMU_LEAK 
	  Add a simple leak tracer to the IOMMU code. This is useful when you

	  are debugging a buggy device driver that leaks IOMMU mappings.



config MMIOTRACE

	bool "Memory mapped IO tracing"

	depends on DEBUG_KERNEL && PCI

	select TRACING

	help

	  Mmiotrace traces Memory Mapped I/O access and is meant for

	  debugging and reverse engineering. It is called from the ioremap

	  implementation and works via page faults. Tracing is disabled by

	  default and can be enabled at run-time.



	  See Documentation/tracers/mmiotrace.txt.

	  If you are not helping to develop drivers, say N.



config MMIOTRACE_TEST

	tristate "Test module for mmiotrace"

	depends on MMIOTRACE && m

	help

	  This is a dumb module for testing mmiotrace. It is very dangerous

	  as it will write garbage to IO memory starting at a given address.

	  However, it should be safe to use on e.g. unused portion of VRAM.



	  Say N, unless you absolutely know what you are doing.

config HAVE_MMIOTRACE_SUPPORT

	def_bool y



#

# IO delay types:

kernel/trace/Kconfig

+23 −0
Original line number Diff line number Diff line
@@ -302,4 +302,27 @@ config FTRACE_STARTUP_TEST 
	  functioning properly. It will do tests on all the configured

	  tracers of ftrace.



config MMIOTRACE

	bool "Memory mapped IO tracing"

	depends on HAVE_MMIOTRACE_SUPPORT && DEBUG_KERNEL && PCI

	select TRACING

	help

	  Mmiotrace traces Memory Mapped I/O access and is meant for

	  debugging and reverse engineering. It is called from the ioremap

	  implementation and works via page faults. Tracing is disabled by

	  default and can be enabled at run-time.



	  See Documentation/tracers/mmiotrace.txt.

	  If you are not helping to develop drivers, say N.



config MMIOTRACE_TEST

	tristate "Test module for mmiotrace"

	depends on MMIOTRACE && m

	help

	  This is a dumb module for testing mmiotrace. It is very dangerous

	  as it will write garbage to IO memory starting at a given address.

	  However, it should be safe to use on e.g. unused portion of VRAM.



	  Say N, unless you absolutely know what you are doing.



endmenu

kernel/trace/trace_mmiotrace.c

+10 −4
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
#include <linux/kernel.h>

#include <linux/mmiotrace.h>

#include <linux/pci.h>

#include <asm/atomic.h>



#include "trace.h"
@@ -19,6 +20,7 @@ struct header_iter { 
static struct trace_array *mmio_trace_array;

static bool overrun_detected;

static unsigned long prev_overruns;

static atomic_t dropped_count;



static void mmio_reset_data(struct trace_array *tr)

{
@@ -121,11 +123,11 @@ static void mmio_close(struct trace_iterator *iter) 


static unsigned long count_overruns(struct trace_iterator *iter)

{

	unsigned long cnt = 0;

	unsigned long cnt = atomic_xchg(&dropped_count, 0);

	unsigned long over = ring_buffer_overruns(iter->tr->buffer);



	if (over > prev_overruns)

		cnt = over - prev_overruns;

		cnt += over - prev_overruns;

	prev_overruns = over;

	return cnt;

}
@@ -310,8 +312,10 @@ static void __trace_mmiotrace_rw(struct trace_array *tr, 


	event	= ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),

					   &irq_flags);

	if (!event)

	if (!event) {

		atomic_inc(&dropped_count);

		return;

	}

	entry	= ring_buffer_event_data(event);

	tracing_generic_entry_update(&entry->ent, 0, preempt_count());

	entry->ent.type			= TRACE_MMIO_RW;
@@ -338,8 +342,10 @@ static void __trace_mmiotrace_map(struct trace_array *tr, 


	event	= ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),

					   &irq_flags);

	if (!event)

	if (!event) {

		atomic_inc(&dropped_count);

		return;

	}

	entry	= ring_buffer_event_data(event);

	tracing_generic_entry_update(&entry->ent, 0, preempt_count());

	entry->ent.type			= TRACE_MMIO_MAP;