1 files changed, 465 insertions, 0 deletions
diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c
new file mode 100644
index 000000000..9210a95cb
--- /dev/null
+++ b/drivers/oprofile/cpu_buffer.c
@@ -0,0 +1,465 @@
+/**
+ * @file cpu_buffer.c
+ *
+ * @remark Copyright 2002-2009 OProfile authors
+ * @remark Read the file COPYING
+ *
+ * @author John Levon <levon@movementarian.org>
+ * @author Barry Kasindorf <barry.kasindorf@amd.com>
+ * @author Robert Richter <robert.richter@amd.com>
+ *
+ * Each CPU has a local buffer that stores PC value/event
+ * pairs. We also log context switches when we notice them.
+ * Eventually each CPU's buffer is processed into the global
+ * event buffer by sync_buffer().
+ *
+ * We use a local buffer for two reasons: an NMI or similar
+ * interrupt cannot synchronise, and high sampling rates
+ * would lead to catastrophic global synchronisation if
+ * a global buffer was used.
+ */
+
+#include <linux/sched.h>
+#include <linux/oprofile.h>
+#include <linux/errno.h>
+
+#include <asm/ptrace.h>
+
+#include "event_buffer.h"
+#include "cpu_buffer.h"
+#include "buffer_sync.h"
+#include "oprof.h"
+
+#define OP_BUFFER_FLAGS	0
+
+static struct trace_buffer *op_ring_buffer;
+DEFINE_PER_CPU(struct oprofile_cpu_buffer, op_cpu_buffer);
+
+static void wq_sync_buffer(struct work_struct *work);
+
+#define DEFAULT_TIMER_EXPIRE (HZ / 10)
+static int work_enabled;
+
+unsigned long oprofile_get_cpu_buffer_size(void)
+{
+	return oprofile_cpu_buffer_size;
+}
+
+void oprofile_cpu_buffer_inc_smpl_lost(void)
+{
+	struct oprofile_cpu_buffer *cpu_buf = this_cpu_ptr(&op_cpu_buffer);
+
+	cpu_buf->sample_lost_overflow++;
+}
+
+void free_cpu_buffers(void)
+{
+	if (op_ring_buffer)
+		ring_buffer_free(op_ring_buffer);
+	op_ring_buffer = NULL;
+}
+
+#define RB_EVENT_HDR_SIZE 4
+
+int alloc_cpu_buffers(void)
+{
+	int i;
+
+	unsigned long buffer_size = oprofile_cpu_buffer_size;
+	unsigned long byte_size = buffer_size * (sizeof(struct op_sample) +
+						 RB_EVENT_HDR_SIZE);
+
+	op_ring_buffer = ring_buffer_alloc(byte_size, OP_BUFFER_FLAGS);
+	if (!op_ring_buffer)
+		goto fail;
+
+	for_each_possible_cpu(i) {
+		struct oprofile_cpu_buffer *b = &per_cpu(op_cpu_buffer, i);
+
+		b->last_task = NULL;
+		b->last_is_kernel = -1;
+		b->tracing = 0;
+		b->buffer_size = buffer_size;
+		b->sample_received = 0;
+		b->sample_lost_overflow = 0;
+		b->backtrace_aborted = 0;
+		b->sample_invalid_eip = 0;
+		b->cpu = i;
+		INIT_DELAYED_WORK(&b->work, wq_sync_buffer);
+	}
+	return 0;
+
+fail:
+	free_cpu_buffers();
+	return -ENOMEM;
+}
+
+void start_cpu_work(void)
+{
+	int i;
+
+	work_enabled = 1;
+
+	for_each_online_cpu(i) {
+		struct oprofile_cpu_buffer *b = &per_cpu(op_cpu_buffer, i);
+
+		/*
+		 * Spread the work by 1 jiffy per cpu so they dont all
+		 * fire at once.
+		 */
+		schedule_delayed_work_on(i, &b->work, DEFAULT_TIMER_EXPIRE + i);
+	}
+}
+
+void end_cpu_work(void)
+{
+	work_enabled = 0;
+}
+
+void flush_cpu_work(void)
+{
+	int i;
+
+	for_each_online_cpu(i) {
+		struct oprofile_cpu_buffer *b = &per_cpu(op_cpu_buffer, i);
+
+		/* these works are per-cpu, no need for flush_sync */
+		flush_delayed_work(&b->work);
+	}
+}
+
+/*
+ * This function prepares the cpu buffer to write a sample.
+ *
+ * Struct op_entry is used during operations on the ring buffer while
+ * struct op_sample contains the data that is stored in the ring
+ * buffer. Struct entry can be uninitialized. The function reserves a
+ * data array that is specified by size. Use
+ * op_cpu_buffer_write_commit() after preparing the sample. In case of
+ * errors a null pointer is returned, otherwise the pointer to the
+ * sample.
+ *
+ */
+struct op_sample
+*op_cpu_buffer_write_reserve(struct op_entry *entry, unsigned long size)
+{
+	entry->event = ring_buffer_lock_reserve
+		(op_ring_buffer, sizeof(struct op_sample) +
+		 size * sizeof(entry->sample->data[0]));
+	if (!entry->event)
+		return NULL;
+	entry->sample = ring_buffer_event_data(entry->event);
+	entry->size = size;
+	entry->data = entry->sample->data;
+
+	return entry->sample;
+}
+
+int op_cpu_buffer_write_commit(struct op_entry *entry)
+{
+	return ring_buffer_unlock_commit(op_ring_buffer, entry->event);
+}
+
+struct op_sample *op_cpu_buffer_read_entry(struct op_entry *entry, int cpu)
+{
+	struct ring_buffer_event *e;
+	e = ring_buffer_consume(op_ring_buffer, cpu, NULL, NULL);
+	if (!e)
+		return NULL;
+
+	entry->event = e;
+	entry->sample = ring_buffer_event_data(e);
+	entry->size = (ring_buffer_event_length(e) - sizeof(struct op_sample))
+		/ sizeof(entry->sample->data[0]);
+	entry->data = entry->sample->data;
+	return entry->sample;
+}
+
+unsigned long op_cpu_buffer_entries(int cpu)
+{
+	return ring_buffer_entries_cpu(op_ring_buffer, cpu);
+}
+
+static int
+op_add_code(struct oprofile_cpu_buffer *cpu_buf, unsigned long backtrace,
+	    int is_kernel, struct task_struct *task)
+{
+	struct op_entry entry;
+	struct op_sample *sample;
+	unsigned long flags;
+	int size;
+
+	flags = 0;
+
+	if (backtrace)
+		flags |= TRACE_BEGIN;
+
+	/* notice a switch from user->kernel or vice versa */
+	is_kernel = !!is_kernel;
+	if (cpu_buf->last_is_kernel != is_kernel) {
+		cpu_buf->last_is_kernel = is_kernel;
+		flags |= KERNEL_CTX_SWITCH;
+		if (is_kernel)
+			flags |= IS_KERNEL;
+	}
+
+	/* notice a task switch */
+	if (cpu_buf->last_task != task) {
+		cpu_buf->last_task = task;
+		flags |= USER_CTX_SWITCH;
+	}
+
+	if (!flags)
+		/* nothing to do */
+		return 0;
+
+	if (flags & USER_CTX_SWITCH)
+		size = 1;
+	else
+		size = 0;
+
+	sample = op_cpu_buffer_write_reserve(&entry, size);
+	if (!sample)
+		return -ENOMEM;
+
+	sample->eip = ESCAPE_CODE;
+	sample->event = flags;
+
+	if (size)
+		op_cpu_buffer_add_data(&entry, (unsigned long)task);
+
+	op_cpu_buffer_write_commit(&entry);
+
+	return 0;
+}
+
+static inline int
+op_add_sample(struct oprofile_cpu_buffer *cpu_buf,
+	      unsigned long pc, unsigned long event)
+{
+	struct op_entry entry;
+	struct op_sample *sample;
+
+	sample = op_cpu_buffer_write_reserve(&entry, 0);
+	if (!sample)
+		return -ENOMEM;
+
+	sample->eip = pc;
+	sample->event = event;
+
+	return op_cpu_buffer_write_commit(&entry);
+}
+
+/*
+ * This must be safe from any context.
+ *
+ * is_kernel is needed because on some architectures you cannot
+ * tell if you are in kernel or user space simply by looking at
+ * pc. We tag this in the buffer by generating kernel enter/exit
+ * events whenever is_kernel changes
+ */
+static int
+log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc,
+	   unsigned long backtrace, int is_kernel, unsigned long event,
+	   struct task_struct *task)
+{
+	struct task_struct *tsk = task ? task : current;
+	cpu_buf->sample_received++;
+
+	if (pc == ESCAPE_CODE) {
+		cpu_buf->sample_invalid_eip++;
+		return 0;
+	}
+
+	if (op_add_code(cpu_buf, backtrace, is_kernel, tsk))
+		goto fail;
+
+	if (op_add_sample(cpu_buf, pc, event))
+		goto fail;
+
+	return 1;
+
+fail:
+	cpu_buf->sample_lost_overflow++;
+	return 0;
+}
+
+static inline void oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf)
+{
+	cpu_buf->tracing = 1;
+}
+
+static inline void oprofile_end_trace(struct oprofile_cpu_buffer *cpu_buf)
+{
+	cpu_buf->tracing = 0;
+}
+
+static inline void
+__oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
+			  unsigned long event, int is_kernel,
+			  struct task_struct *task)
+{
+	struct oprofile_cpu_buffer *cpu_buf = this_cpu_ptr(&op_cpu_buffer);
+	unsigned long backtrace = oprofile_backtrace_depth;
+
+	/*
+	 * if log_sample() fail we can't backtrace since we lost the
+	 * source of this event
+	 */
+	if (!log_sample(cpu_buf, pc, backtrace, is_kernel, event, task))
+		/* failed */
+		return;
+
+	if (!backtrace)
+		return;
+
+	oprofile_begin_trace(cpu_buf);
+	oprofile_ops.backtrace(regs, backtrace);
+	oprofile_end_trace(cpu_buf);
+}
+
+void oprofile_add_ext_hw_sample(unsigned long pc, struct pt_regs * const regs,
+				unsigned long event, int is_kernel,
+				struct task_struct *task)
+{
+	__oprofile_add_ext_sample(pc, regs, event, is_kernel, task);
+}
+
+void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
+			     unsigned long event, int is_kernel)
+{
+	__oprofile_add_ext_sample(pc, regs, event, is_kernel, NULL);
+}
+
+void oprofile_add_sample(struct pt_regs * const regs, unsigned long event)
+{
+	int is_kernel;
+	unsigned long pc;
+
+	if (likely(regs)) {
+		is_kernel = !user_mode(regs);
+		pc = profile_pc(regs);
+	} else {
+		is_kernel = 0;    /* This value will not be used */
+		pc = ESCAPE_CODE; /* as this causes an early return. */
+	}
+
+	__oprofile_add_ext_sample(pc, regs, event, is_kernel, NULL);
+}
+
+/*
+ * Add samples with data to the ring buffer.
+ *
+ * Use oprofile_add_data(&entry, val) to add data and
+ * oprofile_write_commit(&entry) to commit the sample.
+ */
+void
+oprofile_write_reserve(struct op_entry *entry, struct pt_regs * const regs,
+		       unsigned long pc, int code, int size)
+{
+	struct op_sample *sample;
+	int is_kernel = !user_mode(regs);
+	struct oprofile_cpu_buffer *cpu_buf = this_cpu_ptr(&op_cpu_buffer);
+
+	cpu_buf->sample_received++;
+
+	/* no backtraces for samples with data */
+	if (op_add_code(cpu_buf, 0, is_kernel, current))
+		goto fail;
+
+	sample = op_cpu_buffer_write_reserve(entry, size + 2);
+	if (!sample)
+		goto fail;
+	sample->eip = ESCAPE_CODE;
+	sample->event = 0;		/* no flags */
+
+	op_cpu_buffer_add_data(entry, code);
+	op_cpu_buffer_add_data(entry, pc);
+
+	return;
+
+fail:
+	entry->event = NULL;
+	cpu_buf->sample_lost_overflow++;
+}
+
+int oprofile_add_data(struct op_entry *entry, unsigned long val)
+{
+	if (!entry->event)
+		return 0;
+	return op_cpu_buffer_add_data(entry, val);
+}
+
+int oprofile_add_data64(struct op_entry *entry, u64 val)
+{
+	if (!entry->event)
+		return 0;
+	if (op_cpu_buffer_get_size(entry) < 2)
+		/*
+		 * the function returns 0 to indicate a too small
+		 * buffer, even if there is some space left
+		 */
+		return 0;
+	if (!op_cpu_buffer_add_data(entry, (u32)val))
+		return 0;
+	return op_cpu_buffer_add_data(entry, (u32)(val >> 32));
+}
+
+int oprofile_write_commit(struct op_entry *entry)
+{
+	if (!entry->event)
+		return -EINVAL;
+	return op_cpu_buffer_write_commit(entry);
+}
+
+void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event)
+{
+	struct oprofile_cpu_buffer *cpu_buf = this_cpu_ptr(&op_cpu_buffer);
+	log_sample(cpu_buf, pc, 0, is_kernel, event, NULL);
+}
+
+void oprofile_add_trace(unsigned long pc)
+{
+	struct oprofile_cpu_buffer *cpu_buf = this_cpu_ptr(&op_cpu_buffer);
+
+	if (!cpu_buf->tracing)
+		return;
+
+	/*
+	 * broken frame can give an eip with the same value as an
+	 * escape code, abort the trace if we get it
+	 */
+	if (pc == ESCAPE_CODE)
+		goto fail;
+
+	if (op_add_sample(cpu_buf, pc, 0))
+		goto fail;
+
+	return;
+fail:
+	cpu_buf->tracing = 0;
+	cpu_buf->backtrace_aborted++;
+	return;
+}
+
+/*
+ * This serves to avoid cpu buffer overflow, and makes sure
+ * the task mortuary progresses
+ *
+ * By using schedule_delayed_work_on and then schedule_delayed_work
+ * we guarantee this will stay on the correct cpu
+ */
+static void wq_sync_buffer(struct work_struct *work)
+{
+	struct oprofile_cpu_buffer *b =
+		container_of(work, struct oprofile_cpu_buffer, work.work);
+	if (b->cpu != smp_processor_id() && !cpu_online(b->cpu)) {
+		cancel_delayed_work(&b->work);
+		return;
+	}
+	sync_buffer(b->cpu);
+
+	/* don't re-add the work if we're shutting down */
+	if (work_enabled)
+		schedule_delayed_work(&b->work, DEFAULT_TIMER_EXPIRE);
+}