trace: move backend-specific code into the trace/ directory

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>

1 files changed, 355 insertions, 0 deletions

diff --git a/trace/simple.c b/trace/simple.c
new file mode 100644
index 0000000000..de355e9675
--- /dev/null
+++ b/trace/simple.c
@@ -0,0 +1,355 @@
+/*
+ * Simple trace backend
+ *
+ * Copyright IBM, Corp. 2010
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <time.h>
+#include <signal.h>
+#include <pthread.h>
+#include "qemu-timer.h"
+#include "trace.h"
+
+/** Trace file header event ID */
+#define HEADER_EVENT_ID (~(uint64_t)0) /* avoids conflicting with TraceEventIDs */
+
+/** Trace file magic number */
+#define HEADER_MAGIC 0xf2b177cb0aa429b4ULL
+
+/** Trace file version number, bump if format changes */
+#define HEADER_VERSION 0
+
+/** Records were dropped event ID */
+#define DROPPED_EVENT_ID (~(uint64_t)0 - 1)
+
+/** Trace record is valid */
+#define TRACE_RECORD_VALID ((uint64_t)1 << 63)
+
+/** Trace buffer entry */
+typedef struct {
+    uint64_t event;
+    uint64_t timestamp_ns;
+    uint64_t x1;
+    uint64_t x2;
+    uint64_t x3;
+    uint64_t x4;
+    uint64_t x5;
+    uint64_t x6;
+} TraceRecord;
+
+enum {
+    TRACE_BUF_LEN = 4096,
+    TRACE_BUF_FLUSH_THRESHOLD = TRACE_BUF_LEN / 4,
+};
+
+/*
+ * Trace records are written out by a dedicated thread.  The thread waits for
+ * records to become available, writes them out, and then waits again.
+ */
+static pthread_mutex_t trace_lock = PTHREAD_MUTEX_INITIALIZER;
+static pthread_cond_t trace_available_cond = PTHREAD_COND_INITIALIZER;
+static pthread_cond_t trace_empty_cond = PTHREAD_COND_INITIALIZER;
+static bool trace_available;
+static bool trace_writeout_enabled;
+
+static TraceRecord trace_buf[TRACE_BUF_LEN];
+static unsigned int trace_idx;
+static FILE *trace_fp;
+static char *trace_file_name = NULL;
+
+/**
+ * Read a trace record from the trace buffer
+ *
+ * @idx         Trace buffer index
+ * @record      Trace record to fill
+ *
+ * Returns false if the record is not valid.
+ */
+static bool get_trace_record(unsigned int idx, TraceRecord *record)
+{
+    if (!(trace_buf[idx].event & TRACE_RECORD_VALID)) {
+        return false;
+    }
+
+    __sync_synchronize(); /* read memory barrier before accessing record */
+
+    *record = trace_buf[idx];
+    record->event &= ~TRACE_RECORD_VALID;
+    return true;
+}
+
+/**
+ * Kick writeout thread
+ *
+ * @wait        Whether to wait for writeout thread to complete
+ */
+static void flush_trace_file(bool wait)
+{
+    pthread_mutex_lock(&trace_lock);
+    trace_available = true;
+    pthread_cond_signal(&trace_available_cond);
+
+    if (wait) {
+        pthread_cond_wait(&trace_empty_cond, &trace_lock);
+    }
+
+    pthread_mutex_unlock(&trace_lock);
+}
+
+static void wait_for_trace_records_available(void)
+{
+    pthread_mutex_lock(&trace_lock);
+    while (!(trace_available && trace_writeout_enabled)) {
+        pthread_cond_signal(&trace_empty_cond);
+        pthread_cond_wait(&trace_available_cond, &trace_lock);
+    }
+    trace_available = false;
+    pthread_mutex_unlock(&trace_lock);
+}
+
+static void *writeout_thread(void *opaque)
+{
+    TraceRecord record;
+    unsigned int writeout_idx = 0;
+    unsigned int num_available, idx;
+    size_t unused __attribute__ ((unused));
+
+    for (;;) {
+        wait_for_trace_records_available();
+
+        num_available = trace_idx - writeout_idx;
+        if (num_available > TRACE_BUF_LEN) {
+            record = (TraceRecord){
+                .event = DROPPED_EVENT_ID,
+                .x1 = num_available,
+            };
+            unused = fwrite(&record, sizeof(record), 1, trace_fp);
+            writeout_idx += num_available;
+        }
+
+        idx = writeout_idx % TRACE_BUF_LEN;
+        while (get_trace_record(idx, &record)) {
+            trace_buf[idx].event = 0; /* clear valid bit */
+            unused = fwrite(&record, sizeof(record), 1, trace_fp);
+            idx = ++writeout_idx % TRACE_BUF_LEN;
+        }
+
+        fflush(trace_fp);
+    }
+    return NULL;
+}
+
+static void trace(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3,
+                  uint64_t x4, uint64_t x5, uint64_t x6)
+{
+    unsigned int idx;
+    uint64_t timestamp;
+
+    if (!trace_list[event].state) {
+        return;
+    }
+
+    timestamp = get_clock();
+
+    idx = __sync_fetch_and_add(&trace_idx, 1) % TRACE_BUF_LEN;
+    trace_buf[idx] = (TraceRecord){
+        .event = event,
+        .timestamp_ns = timestamp,
+        .x1 = x1,
+        .x2 = x2,
+        .x3 = x3,
+        .x4 = x4,
+        .x5 = x5,
+        .x6 = x6,
+    };
+    __sync_synchronize(); /* write barrier before marking as valid */
+    trace_buf[idx].event |= TRACE_RECORD_VALID;
+
+    if ((idx + 1) % TRACE_BUF_FLUSH_THRESHOLD == 0) {
+        flush_trace_file(false);
+    }
+}
+
+void trace0(TraceEventID event)
+{
+    trace(event, 0, 0, 0, 0, 0, 0);
+}
+
+void trace1(TraceEventID event, uint64_t x1)
+{
+    trace(event, x1, 0, 0, 0, 0, 0);
+}
+
+void trace2(TraceEventID event, uint64_t x1, uint64_t x2)
+{
+    trace(event, x1, x2, 0, 0, 0, 0);
+}
+
+void trace3(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3)
+{
+    trace(event, x1, x2, x3, 0, 0, 0);
+}
+
+void trace4(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4)
+{
+    trace(event, x1, x2, x3, x4, 0, 0);
+}
+
+void trace5(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5)
+{
+    trace(event, x1, x2, x3, x4, x5, 0);
+}
+
+void trace6(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5, uint64_t x6)
+{
+    trace(event, x1, x2, x3, x4, x5, x6);
+}
+
+void st_set_trace_file_enabled(bool enable)
+{
+    if (enable == !!trace_fp) {
+        return; /* no change */
+    }
+
+    /* Halt trace writeout */
+    flush_trace_file(true);
+    trace_writeout_enabled = false;
+    flush_trace_file(true);
+
+    if (enable) {
+        static const TraceRecord header = {
+            .event = HEADER_EVENT_ID,
+            .timestamp_ns = HEADER_MAGIC,
+            .x1 = HEADER_VERSION,
+        };
+
+        trace_fp = fopen(trace_file_name, "w");
+        if (!trace_fp) {
+            return;
+        }
+
+        if (fwrite(&header, sizeof header, 1, trace_fp) != 1) {
+            fclose(trace_fp);
+            trace_fp = NULL;
+            return;
+        }
+
+        /* Resume trace writeout */
+        trace_writeout_enabled = true;
+        flush_trace_file(false);
+    } else {
+        fclose(trace_fp);
+        trace_fp = NULL;
+    }
+}
+
+/**
+ * Set the name of a trace file
+ *
+ * @file        The trace file name or NULL for the default name-<pid> set at
+ *              config time
+ */
+bool st_set_trace_file(const char *file)
+{
+    st_set_trace_file_enabled(false);
+
+    free(trace_file_name);
+
+    if (!file) {
+        if (asprintf(&trace_file_name, CONFIG_TRACE_FILE, getpid()) < 0) {
+            trace_file_name = NULL;
+            return false;
+        }
+    } else {
+        if (asprintf(&trace_file_name, "%s", file) < 0) {
+            trace_file_name = NULL;
+            return false;
+        }
+    }
+
+    st_set_trace_file_enabled(true);
+    return true;
+}
+
+void st_print_trace_file_status(FILE *stream, int (*stream_printf)(FILE *stream, const char *fmt, ...))
+{
+    stream_printf(stream, "Trace file \"%s\" %s.\n",
+                  trace_file_name, trace_fp ? "on" : "off");
+}
+
+void st_print_trace(FILE *stream, int (*stream_printf)(FILE *stream, const char *fmt, ...))
+{
+    unsigned int i;
+
+    for (i = 0; i < TRACE_BUF_LEN; i++) {
+        TraceRecord record;
+
+        if (!get_trace_record(i, &record)) {
+            continue;
+        }
+        stream_printf(stream, "Event %" PRIu64 " : %" PRIx64 " %" PRIx64
+                      " %" PRIx64 " %" PRIx64 " %" PRIx64 " %" PRIx64 "\n",
+                      record.event, record.x1, record.x2,
+                      record.x3, record.x4, record.x5,
+                      record.x6);
+    }
+}
+
+void st_print_trace_events(FILE *stream, int (*stream_printf)(FILE *stream, const char *fmt, ...))
+{
+    unsigned int i;
+
+    for (i = 0; i < NR_TRACE_EVENTS; i++) {
+        stream_printf(stream, "%s [Event ID %u] : state %u\n",
+                      trace_list[i].tp_name, i, trace_list[i].state);
+    }
+}
+
+bool st_change_trace_event_state(const char *name, bool enabled)
+{
+    unsigned int i;
+
+    for (i = 0; i < NR_TRACE_EVENTS; i++) {
+        if (!strcmp(trace_list[i].tp_name, name)) {
+            trace_list[i].state = enabled;
+            return true;
+        }
+    }
+    return false;
+}
+
+void st_flush_trace_buffer(void)
+{
+    flush_trace_file(true);
+}
+
+bool st_init(const char *file)
+{
+    pthread_t thread;
+    pthread_attr_t attr;
+    sigset_t set, oldset;
+    int ret;
+
+    pthread_attr_init(&attr);
+    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+
+    sigfillset(&set);
+    pthread_sigmask(SIG_SETMASK, &set, &oldset);
+    ret = pthread_create(&thread, &attr, writeout_thread, NULL);
+    pthread_sigmask(SIG_SETMASK, &oldset, NULL);
+
+    if (ret != 0) {
+        return false;
+    }
+
+    atexit(st_flush_trace_buffer);
+    st_set_trace_file(file);
+    return true;
+}