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/* -*- linux-c -*- */
/** @file io.c
* @brief I/O functions
*/
/** Logs data.
* This function is compatible with printk. In fact it currently
* sends all output to vprintk, after sending "STP: ". This allows
* us to easily detect SystemTap output in the log file.
*
* @param fmt A variable number of args.
* @bug Lines are limited in length by printk buffer.
* @todo Needs replaced with something much faster that does not
* use the system log.
*/
void dlog (const char *fmt, ...)
{
va_list args;
printk("STP: ");
va_start(args, fmt);
vprintk(fmt, args);
va_end(args);
}
/** Lookup symbol.
* This simply calls the kernel function kallsyms_lookup().
* That function is not exported, so this workaround is required.
* See the kernel source, kernel/kallsyms.c for more information.
*/
static const char * (*_stp_kallsyms_lookup)(unsigned long addr,
unsigned long *symbolsize,
unsigned long *offset,
char **modname, char *namebuf)=(void *)KALLSYMS_LOOKUP;
#define STP_BUF_LEN 8191
/** Static buffer for printing */
static char _stp_pbuf[STP_BUF_LEN+1];
static int _stp_pbuf_len = STP_BUF_LEN;
/** Print into the print buffer.
* Like printf, except output goes into _stp_pbuf,
* which will contain the null-terminated output.
* Safe because overflowing _stp_pbuf is not allowed.
* Size is limited by length of print buffer.
*
* @param fmt A variable number of args.
* @note Formatting output should never be done within
* a probe. Use at module exit time.
* @sa _stp_print_buf_init
*/
void _stp_print_buf (const char *fmt, ...)
{
int num;
va_list args;
char *buf = _stp_pbuf + STP_BUF_LEN - _stp_pbuf_len;
va_start(args, fmt);
num = vscnprintf(buf, _stp_pbuf_len, fmt, args);
va_end(args);
if (num > 0)
_stp_pbuf_len -= num;
}
/** Clear the print buffer.
* Output from _stp_print_buf() will accumulate in the buffer
* until this is called.
*/
void _stp_print_buf_init (void)
{
_stp_pbuf_len = STP_BUF_LEN;
_stp_pbuf[0] = 0;
}
/** Print addresses symbolically into the print buffer.
* @param fmt A variable number of args.
* @param address The address to lookup.
* @note Formatting output should never be done within
* a probe. Use at module exit time.
*/
void _stp_print_symbol(const char *fmt, unsigned long address)
{
char *modname;
const char *name;
unsigned long offset, size;
char namebuf[KSYM_NAME_LEN+1];
name = _stp_kallsyms_lookup(address, &size, &offset, &modname, namebuf);
if (!name)
_stp_print_buf("0x%lx", address);
else {
if (modname)
_stp_print_buf("%s+%#lx/%#lx [%s]", name, offset,
size, modname);
else
_stp_print_buf("%s+%#lx/%#lx", name, offset, size);
}
}
/** Get the current return address.
* Call from kprobes (not jprobes).
* @param regs The pt_regs saved by the kprobe.
* @return The return address saved in esp or rsp.
* @note i386 and x86_64 only.
*/
unsigned long cur_ret_addr (struct pt_regs *regs)
{
#ifdef __x86_64__
unsigned long *ra = (unsigned long *)regs->rsp;
#else
unsigned long *ra = (unsigned long *)regs->esp;
#endif
if (ra)
return *ra;
else
return 0;
}
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