1 files changed, 240 insertions, 153 deletions

diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c
index 01d38e78cde1..2e03b6d796d3 100644
--- a/drivers/oprofile/cpu_buffer.c
+++ b/drivers/oprofile/cpu_buffer.c
@@ -1,11 +1,12 @@
 /**
  * @file cpu_buffer.c
  *
- * @remark Copyright 2002 OProfile authors
+ * @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.
@@ -28,6 +29,25 @@
 #include "buffer_sync.h"
 #include "oprof.h"
 
+#define OP_BUFFER_FLAGS 0
+
+/*
+ * Read and write access is using spin locking. Thus, writing to the
+ * buffer by NMI handler (x86) could occur also during critical
+ * sections when reading the buffer. To avoid this, there are 2
+ * buffers for independent read and write access. Read access is in
+ * process context only, write access only in the NMI handler. If the
+ * read buffer runs empty, both buffers are swapped atomically. There
+ * is potentially a small window during swapping where the buffers are
+ * disabled and samples could be lost.
+ *
+ * Using 2 buffers is a little bit overhead, but the solution is clear
+ * and does not require changes in the ring buffer implementation. It
+ * can be changed to a single buffer solution when the ring buffer
+ * access is implemented as non-locking atomic code.
+ */
+static struct ring_buffer *op_ring_buffer_read;
+static struct ring_buffer *op_ring_buffer_write;
 DEFINE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);
 
 static void wq_sync_buffer(struct work_struct *work);
@@ -35,19 +55,9 @@ static void wq_sync_buffer(struct work_struct *work);
 #define DEFAULT_TIMER_EXPIRE (HZ / 10)
 static int work_enabled;
 
-void free_cpu_buffers(void)
-{
-        int i;
-
-        for_each_possible_cpu(i) {
-                vfree(per_cpu(cpu_buffer, i).buffer);
-                per_cpu(cpu_buffer, i).buffer = NULL;
-        }
-}
-
 unsigned long oprofile_get_cpu_buffer_size(void)
 {
-        return fs_cpu_buffer_size;
+        return oprofile_cpu_buffer_size;
 }
 
 void oprofile_cpu_buffer_inc_smpl_lost(void)
@@ -58,26 +68,36 @@ void oprofile_cpu_buffer_inc_smpl_lost(void)
         cpu_buf->sample_lost_overflow++;
 }
 
+void free_cpu_buffers(void)
+{
+        if (op_ring_buffer_read)
+                ring_buffer_free(op_ring_buffer_read);
+        op_ring_buffer_read = NULL;
+        if (op_ring_buffer_write)
+                ring_buffer_free(op_ring_buffer_write);
+        op_ring_buffer_write = NULL;
+}
+
 int alloc_cpu_buffers(void)
 {
         int i;
 
-        unsigned long buffer_size = fs_cpu_buffer_size;
+        unsigned long buffer_size = oprofile_cpu_buffer_size;
+
+        op_ring_buffer_read = ring_buffer_alloc(buffer_size, OP_BUFFER_FLAGS);
+        if (!op_ring_buffer_read)
+                goto fail;
+        op_ring_buffer_write = ring_buffer_alloc(buffer_size, OP_BUFFER_FLAGS);
+        if (!op_ring_buffer_write)
+                goto fail;
 
         for_each_possible_cpu(i) {
                 struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);
 
-                b->buffer = vmalloc_node(sizeof(struct op_sample) * buffer_size,
-                        cpu_to_node(i));
-                if (!b->buffer)
-                        goto fail;
-
                 b->last_task = NULL;
                 b->last_is_kernel = -1;
                 b->tracing = 0;
                 b->buffer_size = buffer_size;
-                b->tail_pos = 0;
-                b->head_pos = 0;
                 b->sample_received = 0;
                 b->sample_lost_overflow = 0;
                 b->backtrace_aborted = 0;
@@ -124,73 +144,156 @@ void end_cpu_work(void)
         flush_scheduled_work();
 }
 
-/* Resets the cpu buffer to a sane state. */
-void cpu_buffer_reset(struct oprofile_cpu_buffer *cpu_buf)
+/*
+ * 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)
 {
-        /* reset these to invalid values; the next sample
-         * collected will populate the buffer with proper
-         * values to initialize the buffer
-         */
-        cpu_buf->last_is_kernel = -1;
-        cpu_buf->last_task = NULL;
+        entry->event = ring_buffer_lock_reserve
+                (op_ring_buffer_write, sizeof(struct op_sample) +
+                 size * sizeof(entry->sample->data[0]), &entry->irq_flags);
+        if (entry->event)
+                entry->sample = ring_buffer_event_data(entry->event);
+        else
+                entry->sample = NULL;
+
+        if (!entry->sample)
+                return NULL;
+
+        entry->size = size;
+        entry->data = entry->sample->data;
+
+        return entry->sample;
 }
 
-/* compute number of available slots in cpu_buffer queue */
-static unsigned long nr_available_slots(struct oprofile_cpu_buffer const *b)
+int op_cpu_buffer_write_commit(struct op_entry *entry)
 {
-        unsigned long head = b->head_pos;
-        unsigned long tail = b->tail_pos;
+        return ring_buffer_unlock_commit(op_ring_buffer_write, entry->event,
+                                         entry->irq_flags);
+}
 
-        if (tail > head)
-                return (tail - head) - 1;
+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_read, cpu, NULL);
+        if (e)
+                goto event;
+        if (ring_buffer_swap_cpu(op_ring_buffer_read,
+                                 op_ring_buffer_write,
+                                 cpu))
+                return NULL;
+        e = ring_buffer_consume(op_ring_buffer_read, cpu, NULL);
+        if (e)
+                goto event;
+        return NULL;
+
+event:
+        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;
+}
 
-        return tail + (b->buffer_size - head) - 1;
+unsigned long op_cpu_buffer_entries(int cpu)
+{
+        return ring_buffer_entries_cpu(op_ring_buffer_read, cpu)
+                + ring_buffer_entries_cpu(op_ring_buffer_write, cpu);
 }
 
-static void increment_head(struct oprofile_cpu_buffer *b)
+static int
+op_add_code(struct oprofile_cpu_buffer *cpu_buf, unsigned long backtrace,
+            int is_kernel, struct task_struct *task)
 {
-        unsigned long new_head = b->head_pos + 1;
+        struct op_entry entry;
+        struct op_sample *sample;
+        unsigned long flags;
+        int size;
+
+        flags = 0;
 
-        /* Ensure anything written to the slot before we
-         * increment is visible */
-        wmb();
+        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 (new_head < b->buffer_size)
-                b->head_pos = new_head;
+        if (flags & USER_CTX_SWITCH)
+                size = 1;
         else
-                b->head_pos = 0;
-}
+                size = 0;
 
-static inline void
-add_sample(struct oprofile_cpu_buffer *cpu_buf,
-           unsigned long pc, unsigned long event)
-{
-        struct op_sample *entry = &cpu_buf->buffer[cpu_buf->head_pos];
-        entry->eip = pc;
-        entry->event = event;
-        increment_head(cpu_buf);
+        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 void
-add_code(struct oprofile_cpu_buffer *buffer, unsigned long value)
+static inline int
+op_add_sample(struct oprofile_cpu_buffer *cpu_buf,
+              unsigned long pc, unsigned long event)
 {
-        add_sample(buffer, ESCAPE_CODE, value);
+        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. It's safe writing here
- * because of the head/tail separation of the writer and reader
- * of the CPU buffer.
+/*
+ * 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,
-                      int is_kernel, unsigned long event)
+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;
-
         cpu_buf->sample_received++;
 
         if (pc == ESCAPE_CODE) {
@@ -198,131 +301,115 @@ static int log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc,
                 return 0;
         }
 
-        if (nr_available_slots(cpu_buf) < 3) {
-                cpu_buf->sample_lost_overflow++;
-                return 0;
-        }
-
-        is_kernel = !!is_kernel;
+        if (op_add_code(cpu_buf, backtrace, is_kernel, current))
+                goto fail;
 
-        task = current;
+        if (op_add_sample(cpu_buf, pc, event))
+                goto fail;
 
-        /* notice a switch from user->kernel or vice versa */
-        if (cpu_buf->last_is_kernel != is_kernel) {
-                cpu_buf->last_is_kernel = is_kernel;
-                add_code(cpu_buf, is_kernel);
-        }
-
-        /* notice a task switch */
-        if (cpu_buf->last_task != task) {
-                cpu_buf->last_task = task;
-                add_code(cpu_buf, (unsigned long)task);
-        }
-
-        add_sample(cpu_buf, pc, event);
         return 1;
+
+fail:
+        cpu_buf->sample_lost_overflow++;
+        return 0;
 }
 
-static int oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf)
+static inline void oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf)
 {
-        if (nr_available_slots(cpu_buf) < 4) {
-                cpu_buf->sample_lost_overflow++;
-                return 0;
-        }
-
-        add_code(cpu_buf, CPU_TRACE_BEGIN);
         cpu_buf->tracing = 1;
-        return 1;
 }
 
-static void oprofile_end_trace(struct oprofile_cpu_buffer *cpu_buf)
+static inline void oprofile_end_trace(struct oprofile_cpu_buffer *cpu_buf)
 {
         cpu_buf->tracing = 0;
 }
 
-void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
-                                unsigned long event, int is_kernel)
+static inline void
+__oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
+                          unsigned long event, int is_kernel)
 {
         struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
+        unsigned long backtrace = oprofile_backtrace_depth;
 
-        if (!backtrace_depth) {
-                log_sample(cpu_buf, pc, is_kernel, event);
+        /*
+         * 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))
+                /* failed */
                 return;
-        }
 
-        if (!oprofile_begin_trace(cpu_buf))
+        if (!backtrace)
                 return;
 
-        /* if log_sample() fail we can't backtrace since we lost the source
-         * of this event */
-        if (log_sample(cpu_buf, pc, is_kernel, event))
-                oprofile_ops.backtrace(regs, backtrace_depth);
+        oprofile_begin_trace(cpu_buf);
+        oprofile_ops.backtrace(regs, backtrace);
         oprofile_end_trace(cpu_buf);
 }
 
+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);
+}
+
 void oprofile_add_sample(struct pt_regs * const regs, unsigned long event)
 {
         int is_kernel = !user_mode(regs);
         unsigned long pc = profile_pc(regs);
 
-        oprofile_add_ext_sample(pc, regs, event, is_kernel);
+        __oprofile_add_ext_sample(pc, regs, event, is_kernel);
 }
 
-#ifdef CONFIG_OPROFILE_IBS
-
-#define MAX_IBS_SAMPLE_SIZE 14
-
-void oprofile_add_ibs_sample(struct pt_regs *const regs,
-                             unsigned int *const ibs_sample, int ibs_code)
+/*
+ * 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 = &__get_cpu_var(cpu_buffer);
-        struct task_struct *task;
 
         cpu_buf->sample_received++;
 
-        if (nr_available_slots(cpu_buf) < MAX_IBS_SAMPLE_SIZE) {
-                /* we can't backtrace since we lost the source of this event */
-                cpu_buf->sample_lost_overflow++;
-                return;
-        }
+        /* no backtraces for samples with data */
+        if (op_add_code(cpu_buf, 0, is_kernel, current))
+                goto fail;
 
-        /* notice a switch from user->kernel or vice versa */
-        if (cpu_buf->last_is_kernel != is_kernel) {
-                cpu_buf->last_is_kernel = is_kernel;
-                add_code(cpu_buf, is_kernel);
-        }
+        sample = op_cpu_buffer_write_reserve(entry, size + 2);
+        if (!sample)
+                goto fail;
+        sample->eip = ESCAPE_CODE;
+        sample->event = 0;              /* no flags */
 
-        /* notice a task switch */
-        if (!is_kernel) {
-                task = current;
-                if (cpu_buf->last_task != task) {
-                        cpu_buf->last_task = task;
-                        add_code(cpu_buf, (unsigned long)task);
-                }
-        }
+        op_cpu_buffer_add_data(entry, code);
+        op_cpu_buffer_add_data(entry, pc);
 
-        add_code(cpu_buf, ibs_code);
-        add_sample(cpu_buf, ibs_sample[0], ibs_sample[1]);
-        add_sample(cpu_buf, ibs_sample[2], ibs_sample[3]);
-        add_sample(cpu_buf, ibs_sample[4], ibs_sample[5]);
+        return;
 
-        if (ibs_code == IBS_OP_BEGIN) {
-                add_sample(cpu_buf, ibs_sample[6], ibs_sample[7]);
-                add_sample(cpu_buf, ibs_sample[8], ibs_sample[9]);
-                add_sample(cpu_buf, ibs_sample[10], ibs_sample[11]);
-        }
+fail:
+        cpu_buf->sample_lost_overflow++;
+}
 
-        if (backtrace_depth)
-                oprofile_ops.backtrace(regs, backtrace_depth);
+int oprofile_add_data(struct op_entry *entry, unsigned long val)
+{
+        return op_cpu_buffer_add_data(entry, val);
 }
 
-#endif
+int oprofile_write_commit(struct op_entry *entry)
+{
+        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 = &__get_cpu_var(cpu_buffer);
-        log_sample(cpu_buf, pc, is_kernel, event);
+        log_sample(cpu_buf, pc, 0, is_kernel, event);
 }
 
 void oprofile_add_trace(unsigned long pc)
@@ -332,21 +419,21 @@ void oprofile_add_trace(unsigned long pc)
         if (!cpu_buf->tracing)
                 return;
 
-        if (nr_available_slots(cpu_buf) < 1) {
-                cpu_buf->tracing = 0;
-                cpu_buf->sample_lost_overflow++;
-                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;
 
-        /* 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) {
-                cpu_buf->tracing = 0;
-                cpu_buf->backtrace_aborted++;
-                return;
-        }
+        if (op_add_sample(cpu_buf, pc, 0))
+                goto fail;
 
-        add_sample(cpu_buf, pc, 0);
+        return;
+fail:
+        cpu_buf->tracing = 0;
+        cpu_buf->backtrace_aborted++;
+        return;
 }
 
 /*