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Filename : ucontext-symbols.stp
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// User context symbols tapset
// Copyright (C) 2009-2016 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.

// <tapsetdescription>
// User context symbol functions provide additional information about
// addresses from an application. These functions can provide
// information about the user space map (library) that the event occurred or
// the function symbol of an address.
// </tapsetdescription>

@__private30 function __ustack_raw:long (n:long) %{ /* pragma:unwind */ /* pure */
         /* myproc-unprivileged */ /* pragma:uprobes */
         /* basic sanity check for bounds: */
         if (unlikely(STAP_ARG_n < 0 || STAP_ARG_n >= MAXBACKTRACE))
                  STAP_RETVALUE = 0;
         else
                  STAP_RETVALUE = _stp_stack_user_get (CONTEXT, (unsigned)STAP_ARG_n);
%}

/**
 *  sfunction ustack - Return address at given depth of user stack backtrace
 *  @n: number of levels to descend in the stack.
 *
 *  Description: Performs a simple (user space) backtrace, and returns the
 *  element at the specified position. The results of the backtrace itself
 *  are cached, so that the backtrace computation is performed at most once
 *  no matter how many times ustack() is called, or in what order.
 */
function ustack:long (n:long) {
         __r = __ustack_raw(n);
         if (__r != 0) return __r

         /* fallback: parse backtrace() to go deeper in the stack */
         __b = ubacktrace (); __orig_n = n;
         __sym = tokenize (__b, " ");
         if (__sym == "") @__context_unwind_error(__orig_n);
         while (n > 0) {
               __sym = tokenize ("", " ");
               if (__sym == "") @__context_unwind_error(__orig_n);
               n--;
         }
         return strtol(__sym, 16)
}

/**
 * sfunction usymname - Return the symbol of an address in the current task.
 * @addr: The address to translate.
 *
 * Description: Returns the (function) symbol name associated with the
 * given address if known. If not known it will return the hex string
 * representation of addr.
 */
function usymname:string (addr: long) %{
/* pure */ /* myproc-unprivileged */ /* pragma:vma */ /* pragma:symbols */
	 _stp_snprint_addr(STAP_RETVALUE, MAXSTRINGLEN, STAP_ARG_addr,
			   _STP_SYM_SYMBOL, current);
%}

/**
 * sfunction usymdata - Return the symbol and module offset of an address.
 * @addr: The address to translate.
 *
 * Description: Returns the (function) symbol name associated with the
 * given address in the current task if known, the offset from the
 * start and the size of the symbol, plus the module name (between
 * brackets).  If symbol is unknown, but module is known, the offset
 * inside the module, plus the size of the module is added.  If any
 * element is not known it will be omitted and if the symbol name is
 * unknown it will return the hex string for the given address.
 */
function usymdata:string (addr: long) %{
/* pure */ /* myproc-unprivileged */ /* pragma:vma */ /* pragma:symbols */
	 _stp_snprint_addr(STAP_RETVALUE, MAXSTRINGLEN, STAP_ARG_addr,
			   _STP_SYM_DATA, current);
%}

/**
 * sfunction print_ustack - Print out stack for the current task from string.
 * @stk: String with list of hexadecimal addresses for the current task.
 *
 *  Perform a symbolic lookup of the addresses in the given string,
 *  which is assumed to be the result of a prior call to 
 *  ubacktrace() for the current task.
 * 
 *  Print one line per address, including the address, the
 *  name  of the function containing the address, and an estimate of
 *  its position within that function.  Return nothing.
 *
 * NOTE: it is recommended to use print_usyms() instead of this function.
 */
function print_ustack(stk:string) { print_usyms(stk) }

/**
 * sfunction print_usyms - Print out user stack from string
 * @callers: String with list of hexadecimal (user) addresses
 *
 *  Description: This function performs a symbolic lookup of the addresses
 *  in the given string,
 *  which are assumed to be the result of prior calls to ustack(),
 *  ucallers(), and similar functions.
 * 
 *  Prints one line per address, including the address, the
 *  name of the function containing the address, and an estimate of
 *  its position within that function, as obtained by usymdata().
 *  Returns nothing.
 */
function print_usyms (callers:string) {
         __sym = tokenize (callers, " ");
         while (__sym != "") {
               printf (" %s : %s\n", __sym, usymdata (strtol(__sym,16)));
               __sym = tokenize ("", " ");
         }
}

/**
 * sfunction sprint_ustack - Return stack for the current task from string.
 * @stk: String with list of hexadecimal addresses for the current task.
 *
 * Perform a symbolic lookup of the addresses in the given string,
 * which is assumed to be the result of a prior call to
 * ubacktrace() for the current task.
 *
 * Returns a simple backtrace from the given hex string. One line per
 * address. Includes the symbol name (or hex address if symbol
 * couldn't be resolved) and module name (if found). Includes the
 * offset from the start of the function if found, otherwise the
 * offset will be added to the module (if found, between
 * brackets). Returns the backtrace as string (each line terminated by
 * a newline character).  Note that the returned stack will be
 * truncated to MAXSTRINGLEN, to print fuller and richer stacks use
 * print_ustack.
 *
 * NOTE: it is recommended to use sprint_usyms() instead of this function.
 */
function sprint_ustack:string(stk:string) { sprint_usyms(stk) }

/**
 * sfunction sprint_usyms - Return stack for user addresses from string
 *
 * @callers: String with list of hexadecimal (user) addresses
 *
 * Perform a symbolic lookup of the addresses in the given string,
 * which are assumed to be the result of a prior calls to ustack(),
 * ucallers(), and similar functions.
 *
 * Returns a simple backtrace from the given hex string. One line per
 * address. Includes the symbol name (or hex address if symbol
 * couldn't be resolved) and module name (if found), as obtained from
 * usymdata(). Includes the offset from the start of the function if
 * found, otherwise the offset will be added to the module (if found, between
 * brackets). Returns the backtrace as string (each line terminated by
 * a newline character).  Note that the returned stack will be
 * truncated to MAXSTRINGLEN, to print fuller and richer stacks use
 * print_usyms().
 */
function sprint_usyms (callers:string) {
         __sym = tokenize (callers, " ");
         __foo = ""; __l = 0
         while (__sym != "") {
               // cleanly handle overflow instead of printing partial line:
               __line = sprintf (" %s : %s\n", __sym,
                usymdata (strtol(__sym,16)));
               __l += strlen(__line)
               if (__l > @MAXSTRINGLEN) break
               __foo .= __line
               __sym = tokenize ("", " ")
         }
         return __foo
}

/**
 * sfunction usymfileline - Return the file name and line number of an address.
 * @addr: The address to translate.
 *
 * Description: Returns the file name and the (approximate) line number of the
 * given address, if known. If the file name or the line number cannot be
 * found, the hex string representation of the address will be returned.
 */
function usymfileline:string (addr:long) %{
/* pure */ /* myproc-unprivileged */ /* pragma:symbols */ /* pragma:vma */ /* pragma:lines */
  _stp_snprint_addr(STAP_RETVALUE, MAXSTRINGLEN, STAP_ARG_addr,
                    _STP_SYM_LINENUMBER + _STP_SYM_FILENAME, current);
%}

/**
 * sfunction usymfile - Return the file name of a given address.
 * @addr: The address to translate.
 *
 * Description: Returns the file name of the  given address, if known. If the
 * file name cannot be found, the hex string representation of the address
 * will be returned.
 */
function usymfile:string (addr:long) %{
/* pure */ /* myproc-unprivileged */ /* pragma:symbols */ /* pragma:vma */ /* pragma:lines */
  _stp_snprint_addr(STAP_RETVALUE, MAXSTRINGLEN, STAP_ARG_addr,
                    _STP_SYM_FILENAME, current);
%}

/**
 * sfunction usymline - Return the line number of an address.
 * @addr: The address to translate.
 *
 * Description: Returns the (approximate) line number of the given address, if
 * known. If the line number cannot be found, the hex string representation of
 * the address will be returned.
 */
function usymline:string (addr:long) %{
/* pure */ /* myproc-unprivileged */ /* pragma:symbols */ /* pragma:vma */ /* pragma:lines */
  _stp_snprint_addr(STAP_RETVALUE, MAXSTRINGLEN, STAP_ARG_addr,
                    _STP_SYM_LINENUMBER, current);
%}