Merge tag 'trace-v4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "The biggest change here is the updates to kprobes

  Back in January I posted patches to create function based events.
  These were the events that you suggested I make to allow developers to
  easily create events in code where no trace event exists. After
  posting those changes for review, it was suggested that we implement
  this instead with kprobes.

  The problem with kprobes is that the interface is too complex and
  needs to be simplified. Masami Hiramatsu posted patches in March and
  I've been playing with them a bit. There's been a bit of clean up in
  the kprobe code that was inspired by the function based event patches,
  and a couple of enhancements to the kprobe event interface.

   - If the arch supports it (we added support for x86), you can place a
     kprobe event at the start of a function and use $arg1, $arg2, etc
     to reference the arguments of a function. (Before you needed to
     know what register or where on the stack the argument was).

   - The second is a way to see array of events. For example, if you
     reference a mac address, you can add:

	echo 'p:mac ip_rcv perm_addr=+574($arg2):x8[6]' > kprobe_events

     And this will produce:

	mac: (ip_rcv+0x0/0x140) perm_addr={0x52,0x54,0x0,0xc0,0x76,0xec}

  Other changes include

   - Exporting trace_dump_stack to modules

   - Have the stack tracer trace the entire stack (stop trying to remove
     tracing itself, as we keep removing too much).

   - Added support for SDT in uprobes"

[ SDT - "Statically Defined Tracing" are userspace markers for tracing.
  Let's not use random TLA's in explanations unless they are fairly
  well-established as generic (at least for kernel people) - Linus ]

* tag 'trace-v4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (24 commits)
  tracing: Have stack tracer trace full stack
  tracing: Export trace_dump_stack to modules
  tracing: probeevent: Fix uninitialized used of offset in parse args
  tracing/kprobes: Allow kprobe-events to record module symbol
  tracing/kprobes: Check the probe on unloaded module correctly
  tracing/uprobes: Fix to return -EFAULT if copy_from_user failed
  tracing: probeevent: Add $argN for accessing function args
  x86: ptrace: Add function argument access API
  tracing: probeevent: Add array type support
  tracing: probeevent: Add symbol type
  tracing: probeevent: Unify fetch_insn processing common part
  tracing: probeevent: Append traceprobe_ for exported function
  tracing: probeevent: Return consumed bytes of dynamic area
  tracing: probeevent: Unify fetch type tables
  tracing: probeevent: Introduce new argument fetching code
  tracing: probeevent: Remove NOKPROBE_SYMBOL from print functions
  tracing: probeevent: Cleanup argument field definition
  tracing: probeevent: Cleanup print argument functions
  trace_uprobe: support reference counter in fd-based uprobe
  perf probe: Support SDT markers having reference counter (semaphore)
  ...

1 files changed, 39 insertions, 10 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 5a97f34bc14c..8c490130c4fb 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8376,30 +8376,39 @@ static struct pmu perf_tracepoint = {
  *
  * PERF_PROBE_CONFIG_IS_RETPROBE if set, create kretprobe/uretprobe
  *                               if not set, create kprobe/uprobe
+ *
+ * The following values specify a reference counter (or semaphore in the
+ * terminology of tools like dtrace, systemtap, etc.) Userspace Statically
+ * Defined Tracepoints (USDT). Currently, we use 40 bit for the offset.
+ *
+ * PERF_UPROBE_REF_CTR_OFFSET_BITS	# of bits in config as th offset
+ * PERF_UPROBE_REF_CTR_OFFSET_SHIFT	# of bits to shift left
  */
 enum perf_probe_config {
 	PERF_PROBE_CONFIG_IS_RETPROBE = 1U << 0,  /* [k,u]retprobe */
+	PERF_UPROBE_REF_CTR_OFFSET_BITS = 32,
+	PERF_UPROBE_REF_CTR_OFFSET_SHIFT = 64 - PERF_UPROBE_REF_CTR_OFFSET_BITS,
 };
 
 PMU_FORMAT_ATTR(retprobe, "config:0");
+#endif
 
-static struct attribute *probe_attrs[] = {
+#ifdef CONFIG_KPROBE_EVENTS
+static struct attribute *kprobe_attrs[] = {
 	&format_attr_retprobe.attr,
 	NULL,
 };
 
-static struct attribute_group probe_format_group = {
+static struct attribute_group kprobe_format_group = {
 	.name = "format",
-	.attrs = probe_attrs,
+	.attrs = kprobe_attrs,
 };
 
-static const struct attribute_group *probe_attr_groups[] = {
-	&probe_format_group,
+static const struct attribute_group *kprobe_attr_groups[] = {
+	&kprobe_format_group,
 	NULL,
 };
-#endif
 
-#ifdef CONFIG_KPROBE_EVENTS
 static int perf_kprobe_event_init(struct perf_event *event);
 static struct pmu perf_kprobe = {
 	.task_ctx_nr	= perf_sw_context,
@@ -8409,7 +8418,7 @@ static struct pmu perf_kprobe = {
 	.start		= perf_swevent_start,
 	.stop		= perf_swevent_stop,
 	.read		= perf_swevent_read,
-	.attr_groups	= probe_attr_groups,
+	.attr_groups	= kprobe_attr_groups,
 };
 
 static int perf_kprobe_event_init(struct perf_event *event)
@@ -8441,6 +8450,24 @@ static int perf_kprobe_event_init(struct perf_event *event)
 #endif /* CONFIG_KPROBE_EVENTS */
 
 #ifdef CONFIG_UPROBE_EVENTS
+PMU_FORMAT_ATTR(ref_ctr_offset, "config:32-63");
+
+static struct attribute *uprobe_attrs[] = {
+	&format_attr_retprobe.attr,
+	&format_attr_ref_ctr_offset.attr,
+	NULL,
+};
+
+static struct attribute_group uprobe_format_group = {
+	.name = "format",
+	.attrs = uprobe_attrs,
+};
+
+static const struct attribute_group *uprobe_attr_groups[] = {
+	&uprobe_format_group,
+	NULL,
+};
+
 static int perf_uprobe_event_init(struct perf_event *event);
 static struct pmu perf_uprobe = {
 	.task_ctx_nr	= perf_sw_context,
@@ -8450,12 +8477,13 @@ static struct pmu perf_uprobe = {
 	.start		= perf_swevent_start,
 	.stop		= perf_swevent_stop,
 	.read		= perf_swevent_read,
-	.attr_groups	= probe_attr_groups,
+	.attr_groups	= uprobe_attr_groups,
 };
 
 static int perf_uprobe_event_init(struct perf_event *event)
 {
 	int err;
+	unsigned long ref_ctr_offset;
 	bool is_retprobe;
 
 	if (event->attr.type != perf_uprobe.type)
@@ -8471,7 +8499,8 @@ static int perf_uprobe_event_init(struct perf_event *event)
 		return -EOPNOTSUPP;
 
 	is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;
-	err = perf_uprobe_init(event, is_retprobe);
+	ref_ctr_offset = event->attr.config >> PERF_UPROBE_REF_CTR_OFFSET_SHIFT;
+	err = perf_uprobe_init(event, ref_ctr_offset, is_retprobe);
 	if (err)
 		return err;