00001 /* -*- linux-c -*- */
-00002 /** @file io.c
-00003  * @brief I/O functions
-00004  */
-00005 
-00006 /** Logs data.
-00007  * This function is compatible with printk.  In fact it currently
-00008  * sends all output to vprintk, after sending "STP: ". This allows
-00009  * us to easily detect SystemTap output in the log file.
-00010  *
-00011  * @param fmt A variable number of args.
-00012  * @bug Lines are limited in length by printk buffer.
-00013  * @todo Needs replaced with something much faster that does not
-00014  * use the system log.
-00015  */
-00016 void dlog (const char *fmt, ...)
-00017 {
-00018   va_list args;
-00019   printk("STP: ");
-00020   va_start(args, fmt);
-00021   vprintk(fmt, args);
-00022   va_end(args);
-00023 }
-00024 
-00025 
-00026 /** Lookup symbol.
-00027  * This simply calls the kernel function kallsyms_lookup().
-00028  * That function is not exported, so this workaround is required.
-00029  * See the kernel source, kernel/kallsyms.c for more information.
-00030  */
-00031 static const char * (*_stp_kallsyms_lookup)(unsigned long addr,
-00032                             unsigned long *symbolsize,
-00033                             unsigned long *offset,
-00034                             char **modname, char *namebuf)=(void *)KALLSYMS_LOOKUP;
-00035 
-00036 
-00037 #define STP_BUF_LEN 8191
-00038 
-00039 /** Static buffer for printing */
-00040 static char _stp_pbuf[STP_BUF_LEN+1];
-00041 static int _stp_pbuf_len = STP_BUF_LEN;
-00042 
-00043 /** Print into the print buffer.
-00044  * Like printf, except output goes into  _stp_pbuf,
-00045  * which will contain the null-terminated output.
-00046  * Safe because overflowing _stp_pbuf is not allowed.
-00047  * Size is limited by length of print buffer.
-00048  *
-00049  * @param fmt A variable number of args.
-00050  * @note Formatting output should never be done within
-00051  * a probe. Use at module exit time.
-00052  * @sa _stp_print_buf_init
-00053  */
-00054 
-00055 void _stp_print_buf (const char *fmt, ...)
-00056 {
-00057   int num;
-00058   va_list args;
-00059   char *buf = _stp_pbuf + STP_BUF_LEN - _stp_pbuf_len;
-00060   va_start(args, fmt);
-00061   num = vscnprintf(buf, _stp_pbuf_len, fmt, args);
-00062   va_end(args);
-00063   if (num > 0)
-00064     _stp_pbuf_len -= num;
-00065 }
-00066 
-00067 /** Clear the print buffer.
-00068  * Output from _stp_print_buf() will accumulate in the buffer
-00069  * until this is called.
-00070  */
-00071 
-00072 void _stp_print_buf_init (void)
-00073 {
-00074   _stp_pbuf_len = STP_BUF_LEN;
-00075   _stp_pbuf[0] = 0;
-00076 }
-00077 
-00078 /** Print addresses symbolically into the print buffer.
-00079  * @param fmt A variable number of args.
-00080  * @param address The address to lookup.
-00081  * @note Formatting output should never be done within
-00082  * a probe. Use at module exit time.
-00083  */
-00084 
-00085 void _stp_print_symbol(const char *fmt, unsigned long address)
-00086 {
-00087         char *modname;
-00088         const char *name;
-00089         unsigned long offset, size;
-00090         char namebuf[KSYM_NAME_LEN+1];
-00091 
-00092         name = _stp_kallsyms_lookup(address, &size, &offset, &modname, namebuf);
-00093 
-00094         if (!name)
-00095                 _stp_print_buf("0x%lx", address);
-00096         else {
-00097           if (modname)
-00098             _stp_print_buf("%s+%#lx/%#lx [%s]", name, offset,
-00099                            size, modname);
-00100           else
-00101             _stp_print_buf("%s+%#lx/%#lx", name, offset, size);
-00102         }
-00103 }
-00104 
-00105 /** Get the current return address.
-00106  * Call from kprobes (not jprobes).
-00107  * @param regs The pt_regs saved by the kprobe.
-00108  * @return The return address saved in esp or rsp.
-00109  * @note i386 and x86_64 only.
-00110  */
-00111  
-00112 unsigned long cur_ret_addr (struct pt_regs *regs)
-00113 {
-00114 #ifdef __x86_64__
-00115   unsigned long *ra = (unsigned long *)regs->rsp;
-00116 #else
-00117   unsigned long *ra = (unsigned long *)regs->esp;
-00118 #endif
-00119   if (ra)
-00120     return *ra;
-00121   else
-00122     return 0;
-00123 }
-