Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 1239 insertions, 0 deletions

diff --git a/tools/perf/util/thread-stack.c b/tools/perf/util/thread-stack.c
new file mode 100644
index 000000000..1360f4442
--- /dev/null
+++ b/tools/perf/util/thread-stack.c
@@ -0,0 +1,1239 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * thread-stack.c: Synthesize a thread's stack using call / return events
+ * Copyright (c) 2014, Intel Corporation.
+ */
+
+#include <linux/rbtree.h>
+#include <linux/list.h>
+#include <linux/log2.h>
+#include <linux/zalloc.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include "thread.h"
+#include "event.h"
+#include "machine.h"
+#include "env.h"
+#include "debug.h"
+#include "symbol.h"
+#include "comm.h"
+#include "call-path.h"
+#include "thread-stack.h"
+
+#define STACK_GROWTH 2048
+
+/*
+ * State of retpoline detection.
+ *
+ * RETPOLINE_NONE: no retpoline detection
+ * X86_RETPOLINE_POSSIBLE: x86 retpoline possible
+ * X86_RETPOLINE_DETECTED: x86 retpoline detected
+ */
+enum retpoline_state_t {
+	RETPOLINE_NONE,
+	X86_RETPOLINE_POSSIBLE,
+	X86_RETPOLINE_DETECTED,
+};
+
+/**
+ * struct thread_stack_entry - thread stack entry.
+ * @ret_addr: return address
+ * @timestamp: timestamp (if known)
+ * @ref: external reference (e.g. db_id of sample)
+ * @branch_count: the branch count when the entry was created
+ * @insn_count: the instruction count when the entry was created
+ * @cyc_count the cycle count when the entry was created
+ * @db_id: id used for db-export
+ * @cp: call path
+ * @no_call: a 'call' was not seen
+ * @trace_end: a 'call' but trace ended
+ * @non_call: a branch but not a 'call' to the start of a different symbol
+ */
+struct thread_stack_entry {
+	u64 ret_addr;
+	u64 timestamp;
+	u64 ref;
+	u64 branch_count;
+	u64 insn_count;
+	u64 cyc_count;
+	u64 db_id;
+	struct call_path *cp;
+	bool no_call;
+	bool trace_end;
+	bool non_call;
+};
+
+/**
+ * struct thread_stack - thread stack constructed from 'call' and 'return'
+ *                       branch samples.
+ * @stack: array that holds the stack
+ * @cnt: number of entries in the stack
+ * @sz: current maximum stack size
+ * @trace_nr: current trace number
+ * @branch_count: running branch count
+ * @insn_count: running  instruction count
+ * @cyc_count running  cycle count
+ * @kernel_start: kernel start address
+ * @last_time: last timestamp
+ * @crp: call/return processor
+ * @comm: current comm
+ * @arr_sz: size of array if this is the first element of an array
+ * @rstate: used to detect retpolines
+ * @br_stack_rb: branch stack (ring buffer)
+ * @br_stack_sz: maximum branch stack size
+ * @br_stack_pos: current position in @br_stack_rb
+ * @mispred_all: mark all branches as mispredicted
+ */
+struct thread_stack {
+	struct thread_stack_entry *stack;
+	size_t cnt;
+	size_t sz;
+	u64 trace_nr;
+	u64 branch_count;
+	u64 insn_count;
+	u64 cyc_count;
+	u64 kernel_start;
+	u64 last_time;
+	struct call_return_processor *crp;
+	struct comm *comm;
+	unsigned int arr_sz;
+	enum retpoline_state_t rstate;
+	struct branch_stack *br_stack_rb;
+	unsigned int br_stack_sz;
+	unsigned int br_stack_pos;
+	bool mispred_all;
+};
+
+/*
+ * Assume pid == tid == 0 identifies the idle task as defined by
+ * perf_session__register_idle_thread(). The idle task is really 1 task per cpu,
+ * and therefore requires a stack for each cpu.
+ */
+static inline bool thread_stack__per_cpu(struct thread *thread)
+{
+	return !(thread__tid(thread) || thread__pid(thread));
+}
+
+static int thread_stack__grow(struct thread_stack *ts)
+{
+	struct thread_stack_entry *new_stack;
+	size_t sz, new_sz;
+
+	new_sz = ts->sz + STACK_GROWTH;
+	sz = new_sz * sizeof(struct thread_stack_entry);
+
+	new_stack = realloc(ts->stack, sz);
+	if (!new_stack)
+		return -ENOMEM;
+
+	ts->stack = new_stack;
+	ts->sz = new_sz;
+
+	return 0;
+}
+
+static int thread_stack__init(struct thread_stack *ts, struct thread *thread,
+			      struct call_return_processor *crp,
+			      bool callstack, unsigned int br_stack_sz)
+{
+	int err;
+
+	if (callstack) {
+		err = thread_stack__grow(ts);
+		if (err)
+			return err;
+	}
+
+	if (br_stack_sz) {
+		size_t sz = sizeof(struct branch_stack);
+
+		sz += br_stack_sz * sizeof(struct branch_entry);
+		ts->br_stack_rb = zalloc(sz);
+		if (!ts->br_stack_rb)
+			return -ENOMEM;
+		ts->br_stack_sz = br_stack_sz;
+	}
+
+	if (thread__maps(thread) && maps__machine(thread__maps(thread))) {
+		struct machine *machine = maps__machine(thread__maps(thread));
+		uint16_t e_machine = thread__e_machine(thread, machine, /*e_flags=*/NULL);
+
+		ts->kernel_start = machine__kernel_start(machine);
+		if (e_machine == EM_X86_64 || e_machine == EM_386)
+			ts->rstate = X86_RETPOLINE_POSSIBLE;
+	} else {
+		ts->kernel_start = 1ULL << 63;
+	}
+	ts->crp = crp;
+
+	return 0;
+}
+
+static struct thread_stack *thread_stack__new(struct thread *thread, int cpu,
+					      struct call_return_processor *crp,
+					      bool callstack,
+					      unsigned int br_stack_sz)
+{
+	struct thread_stack *ts = thread__ts(thread), *new_ts;
+	unsigned int old_sz = ts ? ts->arr_sz : 0;
+	unsigned int new_sz = 1;
+
+	if (thread_stack__per_cpu(thread) && cpu > 0)
+		new_sz = roundup_pow_of_two(cpu + 1);
+
+	if (!ts || new_sz > old_sz) {
+		new_ts = calloc(new_sz, sizeof(*ts));
+		if (!new_ts)
+			return NULL;
+		if (ts)
+			memcpy(new_ts, ts, old_sz * sizeof(*ts));
+		new_ts->arr_sz = new_sz;
+		free(thread__ts(thread));
+		thread__set_ts(thread, new_ts);
+		ts = new_ts;
+	}
+
+	if (thread_stack__per_cpu(thread) && cpu > 0 &&
+	    (unsigned int)cpu < ts->arr_sz)
+		ts += cpu;
+
+	if (!ts->stack &&
+	    thread_stack__init(ts, thread, crp, callstack, br_stack_sz))
+		return NULL;
+
+	return ts;
+}
+
+static struct thread_stack *thread__cpu_stack(struct thread *thread, int cpu)
+{
+	struct thread_stack *ts = thread__ts(thread);
+
+	if (cpu < 0)
+		cpu = 0;
+
+	if (!ts || (unsigned int)cpu >= ts->arr_sz)
+		return NULL;
+
+	ts += cpu;
+
+	if (!ts->stack)
+		return NULL;
+
+	return ts;
+}
+
+static inline struct thread_stack *thread__stack(struct thread *thread,
+						    int cpu)
+{
+	if (!thread)
+		return NULL;
+
+	if (thread_stack__per_cpu(thread))
+		return thread__cpu_stack(thread, cpu);
+
+	return thread__ts(thread);
+}
+
+static int thread_stack__push(struct thread_stack *ts, u64 ret_addr,
+			      bool trace_end)
+{
+	int err = 0;
+
+	if (ts->cnt == ts->sz) {
+		err = thread_stack__grow(ts);
+		if (err) {
+			pr_warning("Out of memory: discarding thread stack\n");
+			ts->cnt = 0;
+		}
+	}
+
+	ts->stack[ts->cnt].trace_end = trace_end;
+	ts->stack[ts->cnt++].ret_addr = ret_addr;
+
+	return err;
+}
+
+static void thread_stack__pop(struct thread_stack *ts, u64 ret_addr)
+{
+	size_t i;
+
+	/*
+	 * In some cases there may be functions which are not seen to return.
+	 * For example when setjmp / longjmp has been used.  Or the perf context
+	 * switch in the kernel which doesn't stop and start tracing in exactly
+	 * the same code path.  When that happens the return address will be
+	 * further down the stack.  If the return address is not found at all,
+	 * we assume the opposite (i.e. this is a return for a call that wasn't
+	 * seen for some reason) and leave the stack alone.
+	 */
+	for (i = ts->cnt; i; ) {
+		if (ts->stack[--i].ret_addr == ret_addr) {
+			ts->cnt = i;
+			return;
+		}
+	}
+}
+
+static void thread_stack__pop_trace_end(struct thread_stack *ts)
+{
+	size_t i;
+
+	for (i = ts->cnt; i; ) {
+		if (ts->stack[--i].trace_end)
+			ts->cnt = i;
+		else
+			return;
+	}
+}
+
+static bool thread_stack__in_kernel(struct thread_stack *ts)
+{
+	if (!ts->cnt)
+		return false;
+
+	return ts->stack[ts->cnt - 1].cp->in_kernel;
+}
+
+static int thread_stack__call_return(struct thread *thread,
+				     struct thread_stack *ts, size_t idx,
+				     u64 timestamp, u64 ref, bool no_return)
+{
+	struct call_return_processor *crp = ts->crp;
+	struct thread_stack_entry *tse;
+	struct call_return cr = {
+		.thread = thread,
+		.comm = ts->comm,
+		.db_id = 0,
+	};
+	u64 *parent_db_id;
+
+	tse = &ts->stack[idx];
+	cr.cp = tse->cp;
+	cr.call_time = tse->timestamp;
+	cr.return_time = timestamp;
+	cr.branch_count = ts->branch_count - tse->branch_count;
+	cr.insn_count = ts->insn_count - tse->insn_count;
+	cr.cyc_count = ts->cyc_count - tse->cyc_count;
+	cr.db_id = tse->db_id;
+	cr.call_ref = tse->ref;
+	cr.return_ref = ref;
+	if (tse->no_call)
+		cr.flags |= CALL_RETURN_NO_CALL;
+	if (no_return)
+		cr.flags |= CALL_RETURN_NO_RETURN;
+	if (tse->non_call)
+		cr.flags |= CALL_RETURN_NON_CALL;
+
+	/*
+	 * The parent db_id must be assigned before exporting the child. Note
+	 * it is not possible to export the parent first because its information
+	 * is not yet complete because its 'return' has not yet been processed.
+	 */
+	parent_db_id = idx ? &(tse - 1)->db_id : NULL;
+
+	return crp->process(&cr, parent_db_id, crp->data);
+}
+
+static int __thread_stack__flush(struct thread *thread, struct thread_stack *ts)
+{
+	struct call_return_processor *crp = ts->crp;
+	int err;
+
+	if (!crp) {
+		ts->cnt = 0;
+		ts->br_stack_pos = 0;
+		if (ts->br_stack_rb)
+			ts->br_stack_rb->nr = 0;
+		return 0;
+	}
+
+	while (ts->cnt) {
+		err = thread_stack__call_return(thread, ts, --ts->cnt,
+						ts->last_time, 0, true);
+		if (err) {
+			pr_err("Error flushing thread stack!\n");
+			ts->cnt = 0;
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+int thread_stack__flush(struct thread *thread)
+{
+	struct thread_stack *ts = thread__ts(thread);
+	unsigned int pos;
+	int err = 0;
+
+	if (ts) {
+		for (pos = 0; pos < ts->arr_sz; pos++) {
+			int ret = __thread_stack__flush(thread, ts + pos);
+
+			if (ret)
+				err = ret;
+		}
+	}
+
+	return err;
+}
+
+static void thread_stack__update_br_stack(struct thread_stack *ts, u32 flags,
+					  u64 from_ip, u64 to_ip)
+{
+	struct branch_stack *bs = ts->br_stack_rb;
+	struct branch_entry *be;
+
+	if (!ts->br_stack_pos)
+		ts->br_stack_pos = ts->br_stack_sz;
+
+	ts->br_stack_pos -= 1;
+
+	be              = &bs->entries[ts->br_stack_pos];
+	be->from        = from_ip;
+	be->to          = to_ip;
+	be->flags.value = 0;
+	be->flags.abort = !!(flags & PERF_IP_FLAG_TX_ABORT);
+	be->flags.in_tx = !!(flags & PERF_IP_FLAG_IN_TX);
+	/* No support for mispredict */
+	be->flags.mispred = ts->mispred_all;
+
+	if (bs->nr < ts->br_stack_sz)
+		bs->nr += 1;
+}
+
+int thread_stack__event(struct thread *thread, int cpu, u32 flags, u64 from_ip,
+			u64 to_ip, u16 insn_len, u64 trace_nr, bool callstack,
+			unsigned int br_stack_sz, bool mispred_all)
+{
+	struct thread_stack *ts = thread__stack(thread, cpu);
+
+	if (!thread)
+		return -EINVAL;
+
+	if (!ts) {
+		ts = thread_stack__new(thread, cpu, NULL, callstack, br_stack_sz);
+		if (!ts) {
+			pr_warning("Out of memory: no thread stack\n");
+			return -ENOMEM;
+		}
+		ts->trace_nr = trace_nr;
+		ts->mispred_all = mispred_all;
+	}
+
+	/*
+	 * When the trace is discontinuous, the trace_nr changes.  In that case
+	 * the stack might be completely invalid.  Better to report nothing than
+	 * to report something misleading, so flush the stack.
+	 */
+	if (trace_nr != ts->trace_nr) {
+		if (ts->trace_nr)
+			__thread_stack__flush(thread, ts);
+		ts->trace_nr = trace_nr;
+	}
+
+	if (br_stack_sz)
+		thread_stack__update_br_stack(ts, flags, from_ip, to_ip);
+
+	/*
+	 * Stop here if thread_stack__process() is in use, or not recording call
+	 * stack.
+	 */
+	if (ts->crp || !callstack)
+		return 0;
+
+	if (flags & PERF_IP_FLAG_CALL) {
+		u64 ret_addr;
+
+		if (!to_ip)
+			return 0;
+		ret_addr = from_ip + insn_len;
+		if (ret_addr == to_ip)
+			return 0; /* Zero-length calls are excluded */
+		return thread_stack__push(ts, ret_addr,
+					  flags & PERF_IP_FLAG_TRACE_END);
+	} else if (flags & PERF_IP_FLAG_TRACE_BEGIN) {
+		/*
+		 * If the caller did not change the trace number (which would
+		 * have flushed the stack) then try to make sense of the stack.
+		 * Possibly, tracing began after returning to the current
+		 * address, so try to pop that. Also, do not expect a call made
+		 * when the trace ended, to return, so pop that.
+		 */
+		thread_stack__pop(ts, to_ip);
+		thread_stack__pop_trace_end(ts);
+	} else if ((flags & PERF_IP_FLAG_RETURN) && from_ip) {
+		thread_stack__pop(ts, to_ip);
+	}
+
+	return 0;
+}
+
+void thread_stack__set_trace_nr(struct thread *thread, int cpu, u64 trace_nr)
+{
+	struct thread_stack *ts = thread__stack(thread, cpu);
+
+	if (!ts)
+		return;
+
+	if (trace_nr != ts->trace_nr) {
+		if (ts->trace_nr)
+			__thread_stack__flush(thread, ts);
+		ts->trace_nr = trace_nr;
+	}
+}
+
+static void __thread_stack__free(struct thread *thread, struct thread_stack *ts)
+{
+	__thread_stack__flush(thread, ts);
+	zfree(&ts->stack);
+	zfree(&ts->br_stack_rb);
+}
+
+static void thread_stack__reset(struct thread *thread, struct thread_stack *ts)
+{
+	unsigned int arr_sz = ts->arr_sz;
+
+	__thread_stack__free(thread, ts);
+	memset(ts, 0, sizeof(*ts));
+	ts->arr_sz = arr_sz;
+}
+
+void thread_stack__free(struct thread *thread)
+{
+	struct thread_stack *ts = thread__ts(thread);
+	unsigned int pos;
+
+	if (ts) {
+		for (pos = 0; pos < ts->arr_sz; pos++)
+			__thread_stack__free(thread, ts + pos);
+		free(thread__ts(thread));
+		thread__set_ts(thread, NULL);
+	}
+}
+
+static inline u64 callchain_context(u64 ip, u64 kernel_start)
+{
+	return ip < kernel_start ? PERF_CONTEXT_USER : PERF_CONTEXT_KERNEL;
+}
+
+void thread_stack__sample(struct thread *thread, int cpu,
+			  struct ip_callchain *chain,
+			  size_t sz, u64 ip, u64 kernel_start)
+{
+	struct thread_stack *ts = thread__stack(thread, cpu);
+	u64 context = callchain_context(ip, kernel_start);
+	u64 last_context;
+	size_t i, j;
+
+	if (sz < 2) {
+		chain->nr = 0;
+		return;
+	}
+
+	chain->ips[0] = context;
+	chain->ips[1] = ip;
+
+	if (!ts) {
+		chain->nr = 2;
+		return;
+	}
+
+	last_context = context;
+
+	for (i = 2, j = 1; i < sz && j <= ts->cnt; i++, j++) {
+		ip = ts->stack[ts->cnt - j].ret_addr;
+		context = callchain_context(ip, kernel_start);
+		if (context != last_context) {
+			if (i >= sz - 1)
+				break;
+			chain->ips[i++] = context;
+			last_context = context;
+		}
+		chain->ips[i] = ip;
+	}
+
+	chain->nr = i;
+}
+
+/*
+ * Hardware sample records, created some time after the event occurred, need to
+ * have subsequent addresses removed from the call chain.
+ */
+void thread_stack__sample_late(struct thread *thread, int cpu,
+			       struct ip_callchain *chain, size_t sz,
+			       u64 sample_ip, u64 kernel_start)
+{
+	struct thread_stack *ts = thread__stack(thread, cpu);
+	u64 sample_context = callchain_context(sample_ip, kernel_start);
+	u64 last_context, context, ip;
+	size_t nr = 0, j;
+
+	if (sz < 2) {
+		chain->nr = 0;
+		return;
+	}
+
+	if (!ts)
+		goto out;
+
+	/*
+	 * When tracing kernel space, kernel addresses occur at the top of the
+	 * call chain after the event occurred but before tracing stopped.
+	 * Skip them.
+	 */
+	for (j = 1; j <= ts->cnt; j++) {
+		ip = ts->stack[ts->cnt - j].ret_addr;
+		context = callchain_context(ip, kernel_start);
+		if (context == PERF_CONTEXT_USER ||
+		    (context == sample_context && ip == sample_ip))
+			break;
+	}
+
+	last_context = sample_ip; /* Use sample_ip as an invalid context */
+
+	for (; nr < sz && j <= ts->cnt; nr++, j++) {
+		ip = ts->stack[ts->cnt - j].ret_addr;
+		context = callchain_context(ip, kernel_start);
+		if (context != last_context) {
+			if (nr >= sz - 1)
+				break;
+			chain->ips[nr++] = context;
+			last_context = context;
+		}
+		chain->ips[nr] = ip;
+	}
+out:
+	if (nr) {
+		chain->nr = nr;
+	} else {
+		chain->ips[0] = sample_context;
+		chain->ips[1] = sample_ip;
+		chain->nr = 2;
+	}
+}
+
+void thread_stack__br_sample(struct thread *thread, int cpu,
+			     struct branch_stack *dst, unsigned int sz)
+{
+	struct thread_stack *ts = thread__stack(thread, cpu);
+	const size_t bsz = sizeof(struct branch_entry);
+	struct branch_stack *src;
+	struct branch_entry *be;
+	unsigned int nr;
+
+	dst->nr = 0;
+
+	if (!ts)
+		return;
+
+	src = ts->br_stack_rb;
+	if (!src->nr)
+		return;
+
+	dst->nr = min((unsigned int)src->nr, sz);
+
+	be = &dst->entries[0];
+	nr = min(ts->br_stack_sz - ts->br_stack_pos, (unsigned int)dst->nr);
+	memcpy(be, &src->entries[ts->br_stack_pos], bsz * nr);
+
+	if (src->nr >= ts->br_stack_sz) {
+		sz -= nr;
+		be = &dst->entries[nr];
+		nr = min(ts->br_stack_pos, sz);
+		memcpy(be, &src->entries[0], bsz * nr);
+	}
+}
+
+/* Start of user space branch entries */
+static bool us_start(struct branch_entry *be, u64 kernel_start, bool *start)
+{
+	if (!*start)
+		*start = be->to && be->to < kernel_start;
+
+	return *start;
+}
+
+/*
+ * Start of branch entries after the ip fell in between 2 branches, or user
+ * space branch entries.
+ */
+static bool ks_start(struct branch_entry *be, u64 sample_ip, u64 kernel_start,
+		     bool *start, struct branch_entry *nb)
+{
+	if (!*start) {
+		*start = (nb && sample_ip >= be->to && sample_ip <= nb->from) ||
+			 be->from < kernel_start ||
+			 (be->to && be->to < kernel_start);
+	}
+
+	return *start;
+}
+
+/*
+ * Hardware sample records, created some time after the event occurred, need to
+ * have subsequent addresses removed from the branch stack.
+ */
+void thread_stack__br_sample_late(struct thread *thread, int cpu,
+				  struct branch_stack *dst, unsigned int sz,
+				  u64 ip, u64 kernel_start)
+{
+	struct thread_stack *ts = thread__stack(thread, cpu);
+	struct branch_entry *d, *s, *spos, *ssz;
+	struct branch_stack *src;
+	unsigned int nr = 0;
+	bool start = false;
+
+	dst->nr = 0;
+
+	if (!ts)
+		return;
+
+	src = ts->br_stack_rb;
+	if (!src->nr)
+		return;
+
+	spos = &src->entries[ts->br_stack_pos];
+	ssz  = &src->entries[ts->br_stack_sz];
+
+	d = &dst->entries[0];
+	s = spos;
+
+	if (ip < kernel_start) {
+		/*
+		 * User space sample: start copying branch entries when the
+		 * branch is in user space.
+		 */
+		for (s = spos; s < ssz && nr < sz; s++) {
+			if (us_start(s, kernel_start, &start)) {
+				*d++ = *s;
+				nr += 1;
+			}
+		}
+
+		if (src->nr >= ts->br_stack_sz) {
+			for (s = &src->entries[0]; s < spos && nr < sz; s++) {
+				if (us_start(s, kernel_start, &start)) {
+					*d++ = *s;
+					nr += 1;
+				}
+			}
+		}
+	} else {
+		struct branch_entry *nb = NULL;
+
+		/*
+		 * Kernel space sample: start copying branch entries when the ip
+		 * falls in between 2 branches (or the branch is in user space
+		 * because then the start must have been missed).
+		 */
+		for (s = spos; s < ssz && nr < sz; s++) {
+			if (ks_start(s, ip, kernel_start, &start, nb)) {
+				*d++ = *s;
+				nr += 1;
+			}
+			nb = s;
+		}
+
+		if (src->nr >= ts->br_stack_sz) {
+			for (s = &src->entries[0]; s < spos && nr < sz; s++) {
+				if (ks_start(s, ip, kernel_start, &start, nb)) {
+					*d++ = *s;
+					nr += 1;
+				}
+				nb = s;
+			}
+		}
+	}
+
+	dst->nr = nr;
+}
+
+struct call_return_processor *
+call_return_processor__new(int (*process)(struct call_return *cr, u64 *parent_db_id, void *data),
+			   void *data)
+{
+	struct call_return_processor *crp;
+
+	crp = zalloc(sizeof(struct call_return_processor));
+	if (!crp)
+		return NULL;
+	crp->cpr = call_path_root__new();
+	if (!crp->cpr)
+		goto out_free;
+	crp->process = process;
+	crp->data = data;
+	return crp;
+
+out_free:
+	free(crp);
+	return NULL;
+}
+
+void call_return_processor__free(struct call_return_processor *crp)
+{
+	if (crp) {
+		call_path_root__free(crp->cpr);
+		free(crp);
+	}
+}
+
+static int thread_stack__push_cp(struct thread_stack *ts, u64 ret_addr,
+				 u64 timestamp, u64 ref, struct call_path *cp,
+				 bool no_call, bool trace_end)
+{
+	struct thread_stack_entry *tse;
+	int err;
+
+	if (!cp)
+		return -ENOMEM;
+
+	if (ts->cnt == ts->sz) {
+		err = thread_stack__grow(ts);
+		if (err)
+			return err;
+	}
+
+	tse = &ts->stack[ts->cnt++];
+	tse->ret_addr = ret_addr;
+	tse->timestamp = timestamp;
+	tse->ref = ref;
+	tse->branch_count = ts->branch_count;
+	tse->insn_count = ts->insn_count;
+	tse->cyc_count = ts->cyc_count;
+	tse->cp = cp;
+	tse->no_call = no_call;
+	tse->trace_end = trace_end;
+	tse->non_call = false;
+	tse->db_id = 0;
+
+	return 0;
+}
+
+static int thread_stack__pop_cp(struct thread *thread, struct thread_stack *ts,
+				u64 ret_addr, u64 timestamp, u64 ref,
+				struct symbol *sym)
+{
+	int err;
+
+	if (!ts->cnt)
+		return 1;
+
+	if (ts->cnt == 1) {
+		struct thread_stack_entry *tse = &ts->stack[0];
+
+		if (tse->cp->sym == sym)
+			return thread_stack__call_return(thread, ts, --ts->cnt,
+							 timestamp, ref, false);
+	}
+
+	if (ts->stack[ts->cnt - 1].ret_addr == ret_addr &&
+	    !ts->stack[ts->cnt - 1].non_call) {
+		return thread_stack__call_return(thread, ts, --ts->cnt,
+						 timestamp, ref, false);
+	} else {
+		size_t i = ts->cnt - 1;
+
+		while (i--) {
+			if (ts->stack[i].ret_addr != ret_addr ||
+			    ts->stack[i].non_call)
+				continue;
+			i += 1;
+			while (ts->cnt > i) {
+				err = thread_stack__call_return(thread, ts,
+								--ts->cnt,
+								timestamp, ref,
+								true);
+				if (err)
+					return err;
+			}
+			return thread_stack__call_return(thread, ts, --ts->cnt,
+							 timestamp, ref, false);
+		}
+	}
+
+	return 1;
+}
+
+static int thread_stack__bottom(struct thread_stack *ts,
+				struct perf_sample *sample,
+				struct addr_location *from_al,
+				struct addr_location *to_al, u64 ref)
+{
+	struct call_path_root *cpr = ts->crp->cpr;
+	struct call_path *cp;
+	struct symbol *sym;
+	u64 ip;
+
+	if (sample->ip) {
+		ip = sample->ip;
+		sym = from_al->sym;
+	} else if (sample->addr) {
+		ip = sample->addr;
+		sym = to_al->sym;
+	} else {
+		return 0;
+	}
+
+	cp = call_path__findnew(cpr, &cpr->call_path, sym, ip,
+				ts->kernel_start);
+
+	return thread_stack__push_cp(ts, ip, sample->time, ref, cp,
+				     true, false);
+}
+
+static int thread_stack__pop_ks(struct thread *thread, struct thread_stack *ts,
+				struct perf_sample *sample, u64 ref)
+{
+	u64 tm = sample->time;
+	int err;
+
+	/* Return to userspace, so pop all kernel addresses */
+	while (thread_stack__in_kernel(ts)) {
+		err = thread_stack__call_return(thread, ts, --ts->cnt,
+						tm, ref, true);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int thread_stack__no_call_return(struct thread *thread,
+					struct thread_stack *ts,
+					struct perf_sample *sample,
+					struct addr_location *from_al,
+					struct addr_location *to_al, u64 ref)
+{
+	struct call_path_root *cpr = ts->crp->cpr;
+	struct call_path *root = &cpr->call_path;
+	struct symbol *fsym = from_al->sym;
+	struct symbol *tsym = to_al->sym;
+	struct call_path *cp, *parent;
+	u64 ks = ts->kernel_start;
+	u64 addr = sample->addr;
+	u64 tm = sample->time;
+	u64 ip = sample->ip;
+	int err;
+
+	if (ip >= ks && addr < ks) {
+		/* Return to userspace, so pop all kernel addresses */
+		err = thread_stack__pop_ks(thread, ts, sample, ref);
+		if (err)
+			return err;
+
+		/* If the stack is empty, push the userspace address */
+		if (!ts->cnt) {
+			cp = call_path__findnew(cpr, root, tsym, addr, ks);
+			return thread_stack__push_cp(ts, 0, tm, ref, cp, true,
+						     false);
+		}
+	} else if (thread_stack__in_kernel(ts) && ip < ks) {
+		/* Return to userspace, so pop all kernel addresses */
+		err = thread_stack__pop_ks(thread, ts, sample, ref);
+		if (err)
+			return err;
+	}
+
+	if (ts->cnt)
+		parent = ts->stack[ts->cnt - 1].cp;
+	else
+		parent = root;
+
+	if (parent->sym == from_al->sym) {
+		/*
+		 * At the bottom of the stack, assume the missing 'call' was
+		 * before the trace started. So, pop the current symbol and push
+		 * the 'to' symbol.
+		 */
+		if (ts->cnt == 1) {
+			err = thread_stack__call_return(thread, ts, --ts->cnt,
+							tm, ref, false);
+			if (err)
+				return err;
+		}
+
+		if (!ts->cnt) {
+			cp = call_path__findnew(cpr, root, tsym, addr, ks);
+
+			return thread_stack__push_cp(ts, addr, tm, ref, cp,
+						     true, false);
+		}
+
+		/*
+		 * Otherwise assume the 'return' is being used as a jump (e.g.
+		 * retpoline) and just push the 'to' symbol.
+		 */
+		cp = call_path__findnew(cpr, parent, tsym, addr, ks);
+
+		err = thread_stack__push_cp(ts, 0, tm, ref, cp, true, false);
+		if (!err)
+			ts->stack[ts->cnt - 1].non_call = true;
+
+		return err;
+	}
+
+	/*
+	 * Assume 'parent' has not yet returned, so push 'to', and then push and
+	 * pop 'from'.
+	 */
+
+	cp = call_path__findnew(cpr, parent, tsym, addr, ks);
+
+	err = thread_stack__push_cp(ts, addr, tm, ref, cp, true, false);
+	if (err)
+		return err;
+
+	cp = call_path__findnew(cpr, cp, fsym, ip, ks);
+
+	err = thread_stack__push_cp(ts, ip, tm, ref, cp, true, false);
+	if (err)
+		return err;
+
+	return thread_stack__call_return(thread, ts, --ts->cnt, tm, ref, false);
+}
+
+static int thread_stack__trace_begin(struct thread *thread,
+				     struct thread_stack *ts, u64 timestamp,
+				     u64 ref)
+{
+	struct thread_stack_entry *tse;
+	int err;
+
+	if (!ts->cnt)
+		return 0;
+
+	/* Pop trace end */
+	tse = &ts->stack[ts->cnt - 1];
+	if (tse->trace_end) {
+		err = thread_stack__call_return(thread, ts, --ts->cnt,
+						timestamp, ref, false);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int thread_stack__trace_end(struct thread_stack *ts,
+				   struct perf_sample *sample, u64 ref)
+{
+	struct call_path_root *cpr = ts->crp->cpr;
+	struct call_path *cp;
+	u64 ret_addr;
+
+	/* No point having 'trace end' on the bottom of the stack */
+	if (!ts->cnt || (ts->cnt == 1 && ts->stack[0].ref == ref))
+		return 0;
+
+	cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp, NULL, 0,
+				ts->kernel_start);
+
+	ret_addr = sample->ip + sample->insn_len;
+
+	return thread_stack__push_cp(ts, ret_addr, sample->time, ref, cp,
+				     false, true);
+}
+
+static bool is_x86_retpoline(const char *name)
+{
+	return strstr(name, "__x86_indirect_thunk_") == name;
+}
+
+/*
+ * x86 retpoline functions pollute the call graph. This function removes them.
+ * This does not handle function return thunks, nor is there any improvement
+ * for the handling of inline thunks or extern thunks.
+ */
+static int thread_stack__x86_retpoline(struct thread_stack *ts,
+				       struct perf_sample *sample,
+				       struct addr_location *to_al)
+{
+	struct thread_stack_entry *tse = &ts->stack[ts->cnt - 1];
+	struct call_path_root *cpr = ts->crp->cpr;
+	struct symbol *sym = tse->cp->sym;
+	struct symbol *tsym = to_al->sym;
+	struct call_path *cp;
+
+	if (sym && is_x86_retpoline(sym->name)) {
+		/*
+		 * This is a x86 retpoline fn. It pollutes the call graph by
+		 * showing up everywhere there is an indirect branch, but does
+		 * not itself mean anything. Here the top-of-stack is removed,
+		 * by decrementing the stack count, and then further down, the
+		 * resulting top-of-stack is replaced with the actual target.
+		 * The result is that the retpoline functions will no longer
+		 * appear in the call graph. Note this only affects the call
+		 * graph, since all the original branches are left unchanged.
+		 */
+		ts->cnt -= 1;
+		sym = ts->stack[ts->cnt - 2].cp->sym;
+		if (sym && sym == tsym && to_al->addr != tsym->start) {
+			/*
+			 * Target is back to the middle of the symbol we came
+			 * from so assume it is an indirect jmp and forget it
+			 * altogether.
+			 */
+			ts->cnt -= 1;
+			return 0;
+		}
+	} else if (sym && sym == tsym) {
+		/*
+		 * Target is back to the symbol we came from so assume it is an
+		 * indirect jmp and forget it altogether.
+		 */
+		ts->cnt -= 1;
+		return 0;
+	}
+
+	cp = call_path__findnew(cpr, ts->stack[ts->cnt - 2].cp, tsym,
+				sample->addr, ts->kernel_start);
+	if (!cp)
+		return -ENOMEM;
+
+	/* Replace the top-of-stack with the actual target */
+	ts->stack[ts->cnt - 1].cp = cp;
+
+	return 0;
+}
+
+int thread_stack__process(struct thread *thread, struct comm *comm,
+			  struct perf_sample *sample,
+			  struct addr_location *from_al,
+			  struct addr_location *to_al, u64 ref,
+			  struct call_return_processor *crp)
+{
+	struct thread_stack *ts = thread__stack(thread, sample->cpu);
+	enum retpoline_state_t rstate;
+	int err = 0;
+
+	if (ts && !ts->crp) {
+		/* Supersede thread_stack__event() */
+		thread_stack__reset(thread, ts);
+		ts = NULL;
+	}
+
+	if (!ts) {
+		ts = thread_stack__new(thread, sample->cpu, crp, true, 0);
+		if (!ts)
+			return -ENOMEM;
+		ts->comm = comm;
+	}
+
+	rstate = ts->rstate;
+	if (rstate == X86_RETPOLINE_DETECTED)
+		ts->rstate = X86_RETPOLINE_POSSIBLE;
+
+	/* Flush stack on exec */
+	if (ts->comm != comm && thread__pid(thread) == thread__tid(thread)) {
+		err = __thread_stack__flush(thread, ts);
+		if (err)
+			return err;
+		ts->comm = comm;
+	}
+
+	/* If the stack is empty, put the current symbol on the stack */
+	if (!ts->cnt) {
+		err = thread_stack__bottom(ts, sample, from_al, to_al, ref);
+		if (err)
+			return err;
+	}
+
+	ts->branch_count += 1;
+	ts->insn_count += sample->insn_cnt;
+	ts->cyc_count += sample->cyc_cnt;
+	ts->last_time = sample->time;
+
+	if (sample->flags & PERF_IP_FLAG_CALL) {
+		bool trace_end = sample->flags & PERF_IP_FLAG_TRACE_END;
+		struct call_path_root *cpr = ts->crp->cpr;
+		struct call_path *cp;
+		u64 ret_addr;
+
+		if (!sample->ip || !sample->addr)
+			return 0;
+
+		ret_addr = sample->ip + sample->insn_len;
+		if (ret_addr == sample->addr)
+			return 0; /* Zero-length calls are excluded */
+
+		cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp,
+					to_al->sym, sample->addr,
+					ts->kernel_start);
+		err = thread_stack__push_cp(ts, ret_addr, sample->time, ref,
+					    cp, false, trace_end);
+
+		/*
+		 * A call to the same symbol but not the start of the symbol,
+		 * may be the start of a x86 retpoline.
+		 */
+		if (!err && rstate == X86_RETPOLINE_POSSIBLE && to_al->sym &&
+		    from_al->sym == to_al->sym &&
+		    to_al->addr != to_al->sym->start)
+			ts->rstate = X86_RETPOLINE_DETECTED;
+
+	} else if (sample->flags & PERF_IP_FLAG_RETURN) {
+		if (!sample->addr) {
+			u32 return_from_kernel = PERF_IP_FLAG_SYSCALLRET |
+						 PERF_IP_FLAG_INTERRUPT;
+
+			if (!(sample->flags & return_from_kernel))
+				return 0;
+
+			/* Pop kernel stack */
+			return thread_stack__pop_ks(thread, ts, sample, ref);
+		}
+
+		if (!sample->ip)
+			return 0;
+
+		/* x86 retpoline 'return' doesn't match the stack */
+		if (rstate == X86_RETPOLINE_DETECTED && ts->cnt > 2 &&
+		    ts->stack[ts->cnt - 1].ret_addr != sample->addr)
+			return thread_stack__x86_retpoline(ts, sample, to_al);
+
+		err = thread_stack__pop_cp(thread, ts, sample->addr,
+					   sample->time, ref, from_al->sym);
+		if (err) {
+			if (err < 0)
+				return err;
+			err = thread_stack__no_call_return(thread, ts, sample,
+							   from_al, to_al, ref);
+		}
+	} else if (sample->flags & PERF_IP_FLAG_TRACE_BEGIN) {
+		err = thread_stack__trace_begin(thread, ts, sample->time, ref);
+	} else if (sample->flags & PERF_IP_FLAG_TRACE_END) {
+		err = thread_stack__trace_end(ts, sample, ref);
+	} else if (sample->flags & PERF_IP_FLAG_BRANCH &&
+		   from_al->sym != to_al->sym && to_al->sym &&
+		   to_al->addr == to_al->sym->start) {
+		struct call_path_root *cpr = ts->crp->cpr;
+		struct call_path *cp;
+
+		/*
+		 * The compiler might optimize a call/ret combination by making
+		 * it a jmp. Make that visible by recording on the stack a
+		 * branch to the start of a different symbol. Note, that means
+		 * when a ret pops the stack, all jmps must be popped off first.
+		 */
+		cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp,
+					to_al->sym, sample->addr,
+					ts->kernel_start);
+		err = thread_stack__push_cp(ts, 0, sample->time, ref, cp, false,
+					    false);
+		if (!err)
+			ts->stack[ts->cnt - 1].non_call = true;
+	}
+
+	return err;
+}
+
+size_t thread_stack__depth(struct thread *thread, int cpu)
+{
+	struct thread_stack *ts = thread__stack(thread, cpu);
+
+	if (!ts)
+		return 0;
+	return ts->cnt;
+}