console.c

xen虚拟机源代码安装包

    (void)vsnprintf(buf, sizeof(buf), fmt, args);
    va_end(args);        

    p = buf;

    while ( (q = strchr(p, '\n')) != NULL )
    {
        *q = '\0';
        if ( start_of_line )
            do_print = printk_prefix_check(p, &p);
        if ( do_print )
        {
            if ( start_of_line )
                printk_start_of_line();
            __putstr(p);
            __putstr("\n");
        }
        start_of_line = 1;
        p = q + 1;
    }

    if ( *p != '\0' )
    {
        if ( start_of_line )
            do_print = printk_prefix_check(p, &p);
        if ( do_print )
        {
            if ( start_of_line )
                printk_start_of_line();
            __putstr(p);
        }
        start_of_line = 0;
    }

    spin_unlock_recursive(&console_lock);
    local_irq_restore(flags);
}

void __init init_console(void)
{
    char *p;

    /* Where should console output go? */
    for ( p = opt_console; p != NULL; p = strchr(p, ',') )
    {
        if ( *p == ',' )
            p++;
        if ( strncmp(p, "com", 3) == 0 )
            sercon_handle = serial_parse_handle(p);
        else if ( strncmp(p, "vga", 3) == 0 )
            vga_init();
    }

    serial_set_rx_handler(sercon_handle, serial_rx);

    /* HELLO WORLD --- start-of-day banner text. */
    spin_lock(&console_lock);
    __putstr(xen_banner());
    spin_unlock(&console_lock);
    printk("Xen version %d.%d%s (%s@%s) (%s) %s\n",
           xen_major_version(), xen_minor_version(), xen_extra_version(),
           xen_compile_by(), xen_compile_domain(),
           xen_compiler(), xen_compile_date());
    printk("Latest ChangeSet: %s\n", xen_changeset());

    if ( opt_sync_console )
    {
        serial_start_sync(sercon_handle);
        add_taint(TAINT_SYNC_CONSOLE);
        printk("Console output is synchronous.\n");
    }
}

void __init console_endboot(void)
{
    int i, j;

    printk("Std. Loglevel: %s", loglvl_str(xenlog_lower_thresh));
    if ( xenlog_upper_thresh != xenlog_lower_thresh )
        printk(" (Rate-limited: %s)", loglvl_str(xenlog_upper_thresh));
    printk("\nGuest Loglevel: %s", loglvl_str(xenlog_guest_lower_thresh));
    if ( xenlog_guest_upper_thresh != xenlog_guest_lower_thresh )
        printk(" (Rate-limited: %s)", loglvl_str(xenlog_guest_upper_thresh));
    printk("\n");

    if ( opt_sync_console )
    {
        printk("**********************************************\n");
        printk("******* WARNING: CONSOLE OUTPUT IS SYNCHRONOUS\n");
        printk("******* This option is intended to aid debugging "
               "of Xen by ensuring\n");
        printk("******* that all output is synchronously delivered "
               "on the serial line.\n");
        printk("******* However it can introduce SIGNIFICANT latencies "
               "and affect\n");
        printk("******* timekeeping. It is NOT recommended for "
               "production use!\n");
        printk("**********************************************\n");
        for ( i = 0; i < 3; i++ )
        {
            printk("%d... ", 3-i);
            for ( j = 0; j < 100; j++ )
            {
                process_pending_timers();
                mdelay(10);
            }
        }
        printk("\n");
    }

    vga_endboot();

    /*
     * If user specifies so, we fool the switch routine to redirect input
     * straight back to Xen. I use this convoluted method so we still print
     * a useful 'how to switch' message.
     */
    if ( opt_conswitch[1] == 'x' )
        xen_rx = !xen_rx;

    /* Serial input is directed to DOM0 by default. */
    switch_serial_input();
}

int console_has(const char *device)
{
    char *p;

    for ( p = opt_console; p != NULL; p = strchr(p, ',') )
    {
        if ( *p == ',' )
            p++;
        if ( strncmp(p, device, strlen(device)) == 0 )
            return 1;
    }

    return 0;
}

void console_start_log_everything(void)
{
    serial_start_log_everything(sercon_handle);
    atomic_inc(&print_everything);
}

void console_end_log_everything(void)
{
    serial_end_log_everything(sercon_handle);
    atomic_dec(&print_everything);
}

void console_force_unlock(void)
{
    spin_lock_init(&console_lock);
    serial_force_unlock(sercon_handle);
    console_start_sync();
}

void console_force_lock(void)
{
    spin_lock(&console_lock);
}

void console_start_sync(void)
{
    atomic_inc(&print_everything);
    serial_start_sync(sercon_handle);
}

void console_end_sync(void)
{
    serial_end_sync(sercon_handle);
    atomic_dec(&print_everything);
}

void console_putc(char c)
{
    serial_putc(sercon_handle, c);
}

int console_getc(void)
{
    return serial_getc(sercon_handle);
}

/*
 * printk rate limiting, lifted from Linux.
 *
 * This enforces a rate limit: not more than one kernel message
 * every printk_ratelimit_ms (millisecs).
 */
int __printk_ratelimit(int ratelimit_ms, int ratelimit_burst)
{
    static DEFINE_SPINLOCK(ratelimit_lock);
    static unsigned long toks = 10 * 5 * 1000;
    static unsigned long last_msg;
    static int missed;
    unsigned long flags;
    unsigned long long now = NOW(); /* ns */
    unsigned long ms;

    do_div(now, 1000000);
    ms = (unsigned long)now;

    spin_lock_irqsave(&ratelimit_lock, flags);
    toks += ms - last_msg;
    last_msg = ms;
    if ( toks > (ratelimit_burst * ratelimit_ms))
        toks = ratelimit_burst * ratelimit_ms;
    if ( toks >= ratelimit_ms )
    {
        int lost = missed;
        missed = 0;
        toks -= ratelimit_ms;
        spin_unlock(&ratelimit_lock);
        if ( lost )
        {
            char lost_str[8];
            snprintf(lost_str, sizeof(lost_str), "%d", lost);
            /* console_lock may already be acquired by printk(). */
            spin_lock_recursive(&console_lock);
            printk_start_of_line();
            __putstr("printk: ");
            __putstr(lost_str);
            __putstr(" messages suppressed.\n");
            spin_unlock_recursive(&console_lock);
        }
        local_irq_restore(flags);
        return 1;
    }
    missed++;
    spin_unlock_irqrestore(&ratelimit_lock, flags);
    return 0;
}

/* minimum time in ms between messages */
int printk_ratelimit_ms = 5 * 1000;

/* number of messages we send before ratelimiting */
int printk_ratelimit_burst = 10;

int printk_ratelimit(void)
{
    return __printk_ratelimit(printk_ratelimit_ms, printk_ratelimit_burst);
}

/*
 * **************************************************************
 * *************** Serial console ring buffer *******************
 * **************************************************************
 */

#ifdef DEBUG_TRACE_DUMP

/* Send output direct to console, or buffer it? */
static volatile int debugtrace_send_to_console;

static char        *debugtrace_buf; /* Debug-trace buffer */
static unsigned int debugtrace_prd; /* Producer index     */
static unsigned int debugtrace_kilobytes = 128, debugtrace_bytes;
static unsigned int debugtrace_used;
static DEFINE_SPINLOCK(debugtrace_lock);
integer_param("debugtrace", debugtrace_kilobytes);

static void debugtrace_dump_worker(void)
{
    if ( (debugtrace_bytes == 0) || !debugtrace_used )
        return;

    printk("debugtrace_dump() starting\n");

    /* Print oldest portion of the ring. */
    ASSERT(debugtrace_buf[debugtrace_bytes - 1] == 0);
    sercon_puts(&debugtrace_buf[debugtrace_prd]);

    /* Print youngest portion of the ring. */
    debugtrace_buf[debugtrace_prd] = '\0';
    sercon_puts(&debugtrace_buf[0]);

    memset(debugtrace_buf, '\0', debugtrace_bytes);

    printk("debugtrace_dump() finished\n");
}

static void debugtrace_toggle(void)
{
    unsigned long flags;

    watchdog_disable();
    spin_lock_irqsave(&debugtrace_lock, flags);

    /*
     * Dump the buffer *before* toggling, in case the act of dumping the
     * buffer itself causes more printk() invocations.
     */
    printk("debugtrace_printk now writing to %s.\n",
           !debugtrace_send_to_console ? "console": "buffer");
    if ( !debugtrace_send_to_console )
        debugtrace_dump_worker();

    debugtrace_send_to_console = !debugtrace_send_to_console;

    spin_unlock_irqrestore(&debugtrace_lock, flags);
    watchdog_enable();

}

void debugtrace_dump(void)
{
    unsigned long flags;

    watchdog_disable();
    spin_lock_irqsave(&debugtrace_lock, flags);

    debugtrace_dump_worker();

    spin_unlock_irqrestore(&debugtrace_lock, flags);
    watchdog_enable();
}

void debugtrace_printk(const char *fmt, ...)
{
    static char    buf[1024];
    static u32 count;

    va_list       args;
    char         *p;
    unsigned long flags;

    if ( debugtrace_bytes == 0 )
        return;

    debugtrace_used = 1;

    spin_lock_irqsave(&debugtrace_lock, flags);

    ASSERT(debugtrace_buf[debugtrace_bytes - 1] == 0);

    snprintf(buf, sizeof(buf), "%u ", ++count);

    va_start(args, fmt);
    (void)vsnprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), fmt, args);
    va_end(args);

    if ( debugtrace_send_to_console )
    {
        serial_puts(sercon_handle, buf);
    }
    else
    {
        for ( p = buf; *p != '\0'; p++ )
        {
            debugtrace_buf[debugtrace_prd++] = *p;            
            /* Always leave a nul byte at the end of the buffer. */
            if ( debugtrace_prd == (debugtrace_bytes - 1) )
                debugtrace_prd = 0;
        }
    }

    spin_unlock_irqrestore(&debugtrace_lock, flags);
}

static void debugtrace_key(unsigned char key)
{
    debugtrace_toggle();
}

static int __init debugtrace_init(void)
{
    int order;
    unsigned int kbytes, bytes;

    /* Round size down to next power of two. */
    while ( (kbytes = (debugtrace_kilobytes & (debugtrace_kilobytes-1))) != 0 )
        debugtrace_kilobytes = kbytes;

    bytes = debugtrace_kilobytes << 10;
    if ( bytes == 0 )
        return 0;

    order = get_order_from_bytes(bytes);
    debugtrace_buf = alloc_xenheap_pages(order);
    ASSERT(debugtrace_buf != NULL);

    memset(debugtrace_buf, '\0', bytes);

    debugtrace_bytes = bytes;

    register_keyhandler(
        'T', debugtrace_key, "toggle debugtrace to console/buffer");

    return 0;
}
__initcall(debugtrace_init);

#endif /* !NDEBUG */


/*
 * **************************************************************
 * *************** Debugging/tracing/error-report ***************
 * **************************************************************
 */

void panic(const char *fmt, ...)
{
    va_list args;
    unsigned long flags;
    static DEFINE_SPINLOCK(lock);
    static char buf[128];
    
    debugtrace_dump();

    /* Protects buf[] and ensure multi-line message prints atomically. */
    spin_lock_irqsave(&lock, flags);

    va_start(args, fmt);
    (void)vsnprintf(buf, sizeof(buf), fmt, args);
    va_end(args);

    console_start_sync();
    printk("\n****************************************\n");
    printk("Panic on CPU %d:\n", smp_processor_id());
    printk(buf);
    printk("****************************************\n\n");
    if ( opt_noreboot )
        printk("Manual reset required ('noreboot' specified)\n");
    else
        printk("Reboot in five seconds...\n");

    spin_unlock_irqrestore(&lock, flags);

    debugger_trap_immediate();

    kexec_crash();

    if ( opt_noreboot )
    {
        machine_halt();
    }
    else
    {
        watchdog_disable();
        machine_restart(5000);
    }
}

void __bug(char *file, int line)
{
    console_start_sync();
    printk("Xen BUG at %s:%d\n", file, line);
    dump_execution_state();
    panic("Xen BUG at %s:%d\n", file, line);
    for ( ; ; ) ;
}

void __warn(char *file, int line)
{
    printk("Xen WARN at %s:%d\n", file, line);
    dump_execution_state();
}


/*
 * **************************************************************
 * ****************** Console suspend/resume ********************
 * **************************************************************
 */

static void suspend_steal_fn(const char *str) { }
static int suspend_steal_id;

int console_suspend(void)
{
    suspend_steal_id = console_steal(sercon_handle, suspend_steal_fn);
    serial_suspend();
    return 0;
}

int console_resume(void)
{
    serial_resume();
    console_giveback(suspend_steal_id);
    return 0;
}

/*
 * Local variables:
 * mode: C
 * c-set-style: "BSD"
 * c-basic-offset: 4
 * tab-width: 4
 * indent-tabs-mode: nil
 * End:
 */