Initial import of qemu-2.4.1HEADmaster

1 files changed, 391 insertions, 0 deletions

diff --git a/trace/simple.c b/trace/simple.c
new file mode 100644
index 00000000..11ad0309
--- /dev/null
+++ b/trace/simple.c
@@ -0,0 +1,391 @@
+/*
+ * 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>
+#ifndef _WIN32
+#include <signal.h>
+#include <pthread.h>
+#endif
+#include "qemu/timer.h"
+#include "trace.h"
+#include "trace/control.h"
+#include "trace/simple.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 3
+
+/** 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 records are written out by a dedicated thread.  The thread waits for
+ * records to become available, writes them out, and then waits again.
+ */
+static CompatGMutex trace_lock;
+static CompatGCond trace_available_cond;
+static CompatGCond trace_empty_cond;
+
+static bool trace_available;
+static bool trace_writeout_enabled;
+
+enum {
+    TRACE_BUF_LEN = 4096 * 64,
+    TRACE_BUF_FLUSH_THRESHOLD = TRACE_BUF_LEN / 4,
+};
+
+uint8_t trace_buf[TRACE_BUF_LEN];
+static volatile gint trace_idx;
+static unsigned int writeout_idx;
+static volatile gint dropped_events;
+static uint32_t trace_pid;
+static FILE *trace_fp;
+static char *trace_file_name;
+
+/* * Trace buffer entry */
+typedef struct {
+    uint64_t event; /*   TraceEventID */
+    uint64_t timestamp_ns;
+    uint32_t length;   /*    in bytes */
+    uint32_t pid;
+    uint64_t arguments[];
+} TraceRecord;
+
+typedef struct {
+    uint64_t header_event_id; /* HEADER_EVENT_ID */
+    uint64_t header_magic;    /* HEADER_MAGIC    */
+    uint64_t header_version;  /* HEADER_VERSION  */
+} TraceLogHeader;
+
+
+static void read_from_buffer(unsigned int idx, void *dataptr, size_t size);
+static unsigned int write_to_buffer(unsigned int idx, void *dataptr, size_t size);
+
+static void clear_buffer_range(unsigned int idx, size_t len)
+{
+    uint32_t num = 0;
+    while (num < len) {
+        if (idx >= TRACE_BUF_LEN) {
+            idx = idx % TRACE_BUF_LEN;
+        }
+        trace_buf[idx++] = 0;
+        num++;
+    }
+}
+/**
+ * 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 **recordptr)
+{
+    uint64_t event_flag = 0;
+    TraceRecord record;
+    /* read the event flag to see if its a valid record */
+    read_from_buffer(idx, &record, sizeof(event_flag));
+
+    if (!(record.event & TRACE_RECORD_VALID)) {
+        return false;
+    }
+
+    smp_rmb(); /* read memory barrier before accessing record */
+    /* read the record header to know record length */
+    read_from_buffer(idx, &record, sizeof(TraceRecord));
+    *recordptr = malloc(record.length); /* dont use g_malloc, can deadlock when traced */
+    /* make a copy of record to avoid being overwritten */
+    read_from_buffer(idx, *recordptr, record.length);
+    smp_rmb(); /* memory barrier before clearing valid flag */
+    (*recordptr)->event &= ~TRACE_RECORD_VALID;
+    /* clear the trace buffer range for consumed record otherwise any byte
+     * with its MSB set may be considered as a valid event id when the writer
+     * thread crosses this range of buffer again.
+     */
+    clear_buffer_range(idx, record.length);
+    return true;
+}
+
+/**
+ * Kick writeout thread
+ *
+ * @wait        Whether to wait for writeout thread to complete
+ */
+static void flush_trace_file(bool wait)
+{
+    g_mutex_lock(&trace_lock);
+    trace_available = true;
+    g_cond_signal(&trace_available_cond);
+
+    if (wait) {
+        g_cond_wait(&trace_empty_cond, &trace_lock);
+    }
+
+    g_mutex_unlock(&trace_lock);
+}
+
+static void wait_for_trace_records_available(void)
+{
+    g_mutex_lock(&trace_lock);
+    while (!(trace_available && trace_writeout_enabled)) {
+        g_cond_signal(&trace_empty_cond);
+        g_cond_wait(&trace_available_cond, &trace_lock);
+    }
+    trace_available = false;
+    g_mutex_unlock(&trace_lock);
+}
+
+static gpointer writeout_thread(gpointer opaque)
+{
+    TraceRecord *recordptr;
+    union {
+        TraceRecord rec;
+        uint8_t bytes[sizeof(TraceRecord) + sizeof(uint64_t)];
+    } dropped;
+    unsigned int idx = 0;
+    int dropped_count;
+    size_t unused __attribute__ ((unused));
+
+    for (;;) {
+        wait_for_trace_records_available();
+
+        if (g_atomic_int_get(&dropped_events)) {
+            dropped.rec.event = DROPPED_EVENT_ID,
+            dropped.rec.timestamp_ns = get_clock();
+            dropped.rec.length = sizeof(TraceRecord) + sizeof(uint64_t),
+            dropped.rec.pid = trace_pid;
+            do {
+                dropped_count = g_atomic_int_get(&dropped_events);
+            } while (!g_atomic_int_compare_and_exchange(&dropped_events,
+                                                        dropped_count, 0));
+            dropped.rec.arguments[0] = dropped_count;
+            unused = fwrite(&dropped.rec, dropped.rec.length, 1, trace_fp);
+        }
+
+        while (get_trace_record(idx, &recordptr)) {
+            unused = fwrite(recordptr, recordptr->length, 1, trace_fp);
+            writeout_idx += recordptr->length;
+            free(recordptr); /* dont use g_free, can deadlock when traced */
+            idx = writeout_idx % TRACE_BUF_LEN;
+        }
+
+        fflush(trace_fp);
+    }
+    return NULL;
+}
+
+void trace_record_write_u64(TraceBufferRecord *rec, uint64_t val)
+{
+    rec->rec_off = write_to_buffer(rec->rec_off, &val, sizeof(uint64_t));
+}
+
+void trace_record_write_str(TraceBufferRecord *rec, const char *s, uint32_t slen)
+{
+    /* Write string length first */
+    rec->rec_off = write_to_buffer(rec->rec_off, &slen, sizeof(slen));
+    /* Write actual string now */
+    rec->rec_off = write_to_buffer(rec->rec_off, (void*)s, slen);
+}
+
+int trace_record_start(TraceBufferRecord *rec, TraceEventID event, size_t datasize)
+{
+    unsigned int idx, rec_off, old_idx, new_idx;
+    uint32_t rec_len = sizeof(TraceRecord) + datasize;
+    uint64_t event_u64 = event;
+    uint64_t timestamp_ns = get_clock();
+
+    do {
+        old_idx = g_atomic_int_get(&trace_idx);
+        smp_rmb();
+        new_idx = old_idx + rec_len;
+
+        if (new_idx - writeout_idx > TRACE_BUF_LEN) {
+            /* Trace Buffer Full, Event dropped ! */
+            g_atomic_int_inc(&dropped_events);
+            return -ENOSPC;
+        }
+    } while (!g_atomic_int_compare_and_exchange(&trace_idx, old_idx, new_idx));
+
+    idx = old_idx % TRACE_BUF_LEN;
+
+    rec_off = idx;
+    rec_off = write_to_buffer(rec_off, &event_u64, sizeof(event_u64));
+    rec_off = write_to_buffer(rec_off, &timestamp_ns, sizeof(timestamp_ns));
+    rec_off = write_to_buffer(rec_off, &rec_len, sizeof(rec_len));
+    rec_off = write_to_buffer(rec_off, &trace_pid, sizeof(trace_pid));
+
+    rec->tbuf_idx = idx;
+    rec->rec_off  = (idx + sizeof(TraceRecord)) % TRACE_BUF_LEN;
+    return 0;
+}
+
+static void read_from_buffer(unsigned int idx, void *dataptr, size_t size)
+{
+    uint8_t *data_ptr = dataptr;
+    uint32_t x = 0;
+    while (x < size) {
+        if (idx >= TRACE_BUF_LEN) {
+            idx = idx % TRACE_BUF_LEN;
+        }
+        data_ptr[x++] = trace_buf[idx++];
+    }
+}
+
+static unsigned int write_to_buffer(unsigned int idx, void *dataptr, size_t size)
+{
+    uint8_t *data_ptr = dataptr;
+    uint32_t x = 0;
+    while (x < size) {
+        if (idx >= TRACE_BUF_LEN) {
+            idx = idx % TRACE_BUF_LEN;
+        }
+        trace_buf[idx++] = data_ptr[x++];
+    }
+    return idx; /* most callers wants to know where to write next */
+}
+
+void trace_record_finish(TraceBufferRecord *rec)
+{
+    TraceRecord record;
+    read_from_buffer(rec->tbuf_idx, &record, sizeof(TraceRecord));
+    smp_wmb(); /* write barrier before marking as valid */
+    record.event |= TRACE_RECORD_VALID;
+    write_to_buffer(rec->tbuf_idx, &record, sizeof(TraceRecord));
+
+    if (((unsigned int)g_atomic_int_get(&trace_idx) - writeout_idx)
+        > TRACE_BUF_FLUSH_THRESHOLD) {
+        flush_trace_file(false);
+    }
+}
+
+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 TraceLogHeader header = {
+            .header_event_id = HEADER_EVENT_ID,
+            .header_magic = HEADER_MAGIC,
+            /* Older log readers will check for version at next location */
+            .header_version = HEADER_VERSION,
+        };
+
+        trace_fp = fopen(trace_file_name, "wb");
+        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);
+
+    g_free(trace_file_name);
+
+    if (!file) {
+        trace_file_name = g_strdup_printf(CONFIG_TRACE_FILE, getpid());
+    } else {
+        trace_file_name = g_strdup_printf("%s", file);
+    }
+
+    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_flush_trace_buffer(void)
+{
+    flush_trace_file(true);
+}
+
+/* Helper function to create a thread with signals blocked.  Use glib's
+ * portable threads since QEMU abstractions cannot be used due to reentrancy in
+ * the tracer.  Also note the signal masking on POSIX hosts so that the thread
+ * does not steal signals when the rest of the program wants them blocked.
+ */
+static GThread *trace_thread_create(GThreadFunc fn)
+{
+    GThread *thread;
+#ifndef _WIN32
+    sigset_t set, oldset;
+
+    sigfillset(&set);
+    pthread_sigmask(SIG_SETMASK, &set, &oldset);
+#endif
+
+    thread = g_thread_new("trace-thread", fn, NULL);
+
+#ifndef _WIN32
+    pthread_sigmask(SIG_SETMASK, &oldset, NULL);
+#endif
+
+    return thread;
+}
+
+bool st_init(const char *file)
+{
+    GThread *thread;
+
+    trace_pid = getpid();
+
+    thread = trace_thread_create(writeout_thread);
+    if (!thread) {
+        fprintf(stderr, "warning: unable to initialize simple trace backend\n");
+        return false;
+    }
+
+    atexit(st_flush_trace_buffer);
+    st_set_trace_file(file);
+    return true;
+}