path: root/runtime/print.c

/* -*- linux-c -*- 
 * Print Functions
 * Copyright (C) 2007-2008 Red Hat Inc.
 *
 * This file is part of systemtap, and is free software.  You can
 * redistribute it and/or modify it under the terms of the GNU General
 * Public License (GPL); either version 2, or (at your option) any
 * later version.
 */

#ifndef _PRINT_C_
#define _PRINT_C_


#include "string.h"
#include "vsprintf.c"
#include "transport/transport.c"

/** @file print.c
 * Printing Functions.
 */

/** @addtogroup print Print Functions
 * The print buffer is for collecting output to send to the user daemon.
 * This is a per-cpu static buffer.  The buffer is sent when
 * _stp_print_flush() is called.
 *
 * The reason to do this is to allow multiple small prints to be combined then
 * timestamped and sent together to staprun. This is more efficient than sending
 * numerous small packets.
 *
 * This function is called automatically when the print buffer is full.
 * It MUST also be called at the end of every probe that prints something.
 * @{
 */

typedef struct __stp_pbuf {
	uint32_t len;			/* bytes used in the buffer */
	char buf[STP_BUFFER_SIZE];
} _stp_pbuf;

static void *Stp_pbuf = NULL;

/** private buffer for _stp_log() */
#define STP_LOG_BUF_LEN 256

typedef char _stp_lbuf[STP_LOG_BUF_LEN];
static void *Stp_lbuf = NULL;

/* create percpu print and io buffers */
static int _stp_print_init (void)
{
	Stp_pbuf = _stp_alloc_percpu(sizeof(_stp_pbuf));
	if (unlikely(Stp_pbuf == 0))
		return -1;

	/* now initialize IO buffer used in io.c */
	Stp_lbuf = _stp_alloc_percpu(sizeof(_stp_lbuf));
	if (unlikely(Stp_lbuf == 0)) {
		_stp_free_percpu(Stp_pbuf);
		return -1;
	}
	return 0;
}

static void _stp_print_cleanup (void)
{
	if (Stp_pbuf)
		_stp_free_percpu(Stp_pbuf);
	if (Stp_lbuf)
		_stp_free_percpu(Stp_lbuf);
}

#define __DEF_EXPORT_FN(fn, postfix) fn ## _ ## postfix
#define DEF_EXPORT_FN(fn, postfix) __DEF_EXPORT_FN(fn, postfix)

#if defined(RELAY_GUEST)
#if defined(RELAY_HOST)
        #error "Cannot specify both RELAY_HOST and RELAY_GUEST"
#endif
#define EXPORT_FN(fn) DEF_EXPORT_FN(fn, RELAY_GUEST)
#elif defined(RELAY_HOST)
#define EXPORT_FN(fn) DEF_EXPORT_FN(fn, RELAY_HOST)
#else /* defined(RELAY_GUEST) || defined(RELAY_HOST) */
#define EXPORT_FN(fn) fn
#endif

#if !defined(RELAY_GUEST)
/* The relayfs API changed between 2.6.15 and 2.6.16. */
/* Use the appropriate print flush function. */

#ifdef STP_OLD_TRANSPORT
#include "print_old.c"
#else
#include "print_new.c"
#endif
#if defined(RELAY_HOST)
EXPORT_SYMBOL_GPL(EXPORT_FN(stp_print_flush));
#endif

#endif /*!RELAY_GUEST*/

#if defined(RELAY_GUEST) || defined(RELAY_HOST)
/* Prohibit irqs to avoid racing on a relayfs */
extern void EXPORT_FN(stp_print_flush) (_stp_pbuf *);
static inline void _stp_print_flush(void)
{
	unsigned long flags;
	local_irq_save(flags);
	EXPORT_FN(stp_print_flush) (per_cpu_ptr(Stp_pbuf, smp_processor_id()));
	local_irq_restore(flags);
}
#else
#define _stp_print_flush() \
	EXPORT_FN(stp_print_flush)(per_cpu_ptr(Stp_pbuf, smp_processor_id()))
#endif

#ifndef STP_MAXBINARYARGS
#define STP_MAXBINARYARGS 127
#endif


/** Reserves space in the output buffer for direct I/O.
 */
static void * _stp_reserve_bytes (int numbytes)
{
	_stp_pbuf *pb = per_cpu_ptr(Stp_pbuf, smp_processor_id());
	int size = STP_BUFFER_SIZE - pb->len;
	void * ret;

	if (unlikely(numbytes == 0 || numbytes > STP_BUFFER_SIZE))
		return NULL;

	if (unlikely(numbytes > size))
		_stp_print_flush();

	ret = pb->buf + pb->len;
	pb->len += numbytes;
	return ret;
}


/** Write 64-bit args directly into the output stream.
 * This function takes a variable number of 64-bit arguments
 * and writes them directly into the output stream.  Marginally faster
 * than doing the same in _stp_vsnprintf().
 * @sa _stp_vsnprintf()
 */
static void _stp_print_binary (int num, ...)
{
	va_list vargs;
	int i;
	int64_t *args;
	
	if (unlikely(num > STP_MAXBINARYARGS))
		num = STP_MAXBINARYARGS;

	args = _stp_reserve_bytes(num * sizeof(int64_t));

	if (likely(args != NULL)) {
		va_start(vargs, num);
		for (i = 0; i < num; i++) {
			args[i] = va_arg(vargs, int64_t);
		}
		va_end(vargs);
	}
}

/** Print into the print buffer.
 * Like C printf.
 *
 * @sa _stp_print_flush()
 */
static void _stp_printf (const char *fmt, ...)
{
	int num;
	va_list args;
	_stp_pbuf *pb = per_cpu_ptr(Stp_pbuf, smp_processor_id());
	char *buf = pb->buf + pb->len;
	int size = STP_BUFFER_SIZE - pb->len;

	va_start(args, fmt);
	num = _stp_vsnprintf(buf, size, fmt, args);
	va_end(args);
	if (unlikely(num >= size)) { 
		/* overflowed the buffer */
		if (pb->len == 0) {
			/* A single print request exceeded the buffer size. */
			/* Should not be possible with Systemtap-generated code. */
			pb->len = STP_BUFFER_SIZE;
			_stp_print_flush();
			num = 0;
		} else {
			/* Need more space. Flush the previous contents */
			_stp_print_flush();
			
			/* try again */
			va_start(args, fmt);
			num = _stp_vsnprintf(pb->buf, STP_BUFFER_SIZE, fmt, args);
			va_end(args);
		}
	}
	pb->len += num;
}

/** Write a string into the print buffer.
 * @param str A C string (char *)
 */

static void _stp_print (const char *str)
{
	_stp_pbuf *pb = per_cpu_ptr(Stp_pbuf, smp_processor_id());
	char *end = pb->buf + STP_BUFFER_SIZE;
	char *ptr = pb->buf + pb->len;
	char *instr = (char *)str;

	while (ptr < end && *instr)
		*ptr++ = *instr++;

	/* Did loop terminate due to lack of buffer space? */
	if (unlikely(*instr)) {
		/* Don't break strings across subbufs. */
		/* Restart after flushing. */
		_stp_print_flush();
		end = pb->buf + STP_BUFFER_SIZE;
		ptr = pb->buf + pb->len;
		instr = (char *)str;
		while (ptr < end && *instr)
			*ptr++ = *instr++;
	}
	pb->len = ptr - pb->buf;
}

static void _stp_print_char (const char c)
{
	char *buf;
	_stp_pbuf *pb = per_cpu_ptr(Stp_pbuf, smp_processor_id());
	int size = STP_BUFFER_SIZE - pb->len;
	if (unlikely(1 >= size))
		_stp_print_flush();
	
	pb->buf[pb->len] = c;
	pb->len ++;
}

/* This function is used when printing maps or stats. */
/* Probably belongs elsewhere, but is here for now. */
/* It takes a format specification like those used for */
/* printing maps and stats. It prints chars until it sees */
/* a special format char (beginning with '%'. Then it */
/* returns a pointer to that. */
static char *next_fmt(char *fmt, int *num)
{
	char *f = fmt;
	int in_fmt = 0;
	*num = 0;
	while (*f) {
		if (in_fmt) {
			if (*f == '%') {
				_stp_print_char('%');
				in_fmt = 0;
			} else if (*f > '0' && *f <= '9') {
				*num = *f - '0';
				f++;
				return f;
			} else
				return f;
		} else if (*f == '%')
			in_fmt = 1;
		else
			_stp_print_char(*f);
		f++;
	}
	return f;
}

static void _stp_print_kernel_info(char *vstr, int ctx, int num_probes)
{
#ifdef DEBUG_MEM
	printk(KERN_DEBUG "%s: systemtap: %s, base: %p, memory: %lu+%lu+%u+%u+%u data+text+ctx+net+alloc, probes: %d\n",
	       THIS_MODULE->name,
	       vstr, 
	       THIS_MODULE->module_core,  
	       (unsigned long) (THIS_MODULE->core_size - THIS_MODULE->core_text_size),
               (unsigned long) THIS_MODULE->core_text_size,
	       ctx,
	       _stp_allocated_net_memory,
	       _stp_allocated_memory - _stp_allocated_net_memory,
		num_probes);
#else
	printk(KERN_DEBUG "%s: systemtap: %s, base: %p, memory: %lu+%lu+%u+%u data+text+ctx+net, probes: %d\n",
	       THIS_MODULE->name,
	       vstr, 
	       THIS_MODULE->module_core,  
	       (unsigned long) (THIS_MODULE->core_size - THIS_MODULE->core_text_size),
               (unsigned long) THIS_MODULE->core_text_size,
	       ctx,
	       _stp_allocated_net_memory,
	       num_probes);
#endif
}

/** @} */
#endif /* _PRINT_C_ */