// context tapset
// Copyright (C) 2005-2009 Red Hat Inc.
// Copyright (C) 2006 Intel Corporation.
//
// 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>
// Context functions provide additional information about where an event occurred. These functions can
//provide information such as a backtrace to where the event occurred and the current register values for the
//processor.
// </tapsetdescription>

%{
#include <asm/processor.h>

#if defined(__powerpc__)
#if !defined(task_pt_regs)
#define task_pt_regs(tsk)       ((struct pt_regs *)(tsk)->thread.regs)
#endif
#endif
%}

/**
 * sfunction print_regs - Print a register dump.
 */
function print_regs () %{
	if (CONTEXT->regs) {
		_stp_print_regs (CONTEXT->regs);
	}
%}

/**
 * sfunction execname - Returns the execname of a target process (or group of processes).
 */
function execname:string () %{ /* pure */ /* unprivileged */
	strlcpy (THIS->__retvalue, current->comm, MAXSTRINGLEN);
%}

/**
 * sfunction pid - Returns the ID of a target process.
 */
function pid:long () %{ /* pure */ /* unprivileged */
	THIS->__retvalue = current->tgid;
%}

/**
 * sfunction tid - Returns the thread ID of a target process.
 */
function tid:long () %{ /* pure */ /* unprivileged */
	THIS->__retvalue = current->pid;
%}

/**
 * sfunction ppid - Returns the process ID of a target process's parent process.
 */
function ppid:long () %{ /* pure */ /* unprivileged */
#if defined(STAPCONF_REAL_PARENT)
	THIS->__retvalue = current->real_parent->tgid;
#else
	THIS->__retvalue = current->parent->tgid;
#endif
%}

/**
 * sfunction pgrp - Returns the process group ID of the current process.
 */
function pgrp:long () %{ /* pure */ /* unprivileged */
#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 24)
	struct signal_struct *ss = kread( &(current->signal) );
	THIS->__retvalue = kread ( &(ss->pgrp) );
	CATCH_DEREF_FAULT();
#else
	THIS->__retvalue = task_pgrp_nr_ns(current, &init_pid_ns);
#endif
%}

/**
 * sfunction sid - Returns the session ID of the current process.
 *
 * The session ID of a process is the process group ID of the session
 * leader. Session ID is stored in the signal_struct since Kernel 2.6.0.
 */
function sid:long () %{ /* pure */ /* unprivileged */
#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 24)
	struct signal_struct *ss = kread( &(current->signal) );
	THIS->__retvalue = kread ( &(ss->session) );
	CATCH_DEREF_FAULT();
#else
	THIS->__retvalue = task_session_nr_ns(current, &init_pid_ns);
#endif
%}

/**
 * sfunction pexecname - Returns the execname of a target process's parent process.
 */
function pexecname:string () %{ /* pure */ /* unprivileged */
#if defined(STAPCONF_REAL_PARENT)
	strlcpy (THIS->__retvalue, current->real_parent->comm, MAXSTRINGLEN);
#else
	strlcpy (THIS->__retvalue, current->parent->comm, MAXSTRINGLEN);
#endif
%}

/**
 * sfunction gid - Returns the group ID of a target process.
 */
function gid:long () %{ /* pure */ /* unprivileged */
#ifdef STAPCONF_TASK_UID
	THIS->__retvalue = current->gid;
#else
	THIS->__retvalue = current_gid();
#endif
%}

/**
 * sfunction egid - Returns the effective gid of a target process.
 */
function egid:long () %{ /* pure */ /* unprivileged */
#ifdef STAPCONF_TASK_UID
	THIS->__retvalue = current->egid;
#else
	THIS->__retvalue = current_egid();
#endif
%}

/**
 * sfunction uid - Returns the user ID of a target process.
 */
function uid:long () %{ /* pure */ /* unprivileged */
#ifdef STAPCONF_TASK_UID
	THIS->__retvalue = current->uid;
#else
	THIS->__retvalue = current_uid();
#endif
%}

/**
 * sfunction euid - Return the effective uid of a target process.
 */
function euid:long () %{ /* pure */ /* unprivileged */
#ifdef STAPCONF_TASK_UID
	THIS->__retvalue = current->euid;
#else
	THIS->__retvalue = current_euid();
#endif
%}


/**
 * sfunction is_myproc - Determines if the current probe point has occurred in the user's own process.
 *
 *  Return 1 if the current probe point has occurred in the user's own process.
 */
function is_myproc:long () %{ /* pure */ /* unprivileged */
        THIS->__retvalue = is_myproc();
%}



// cpuid() is not documented
function cpuid:long () %{ /* pure */
	THIS->__retvalue = smp_processor_id();
%}

/**
 * sfunction cpu - Returns the current cpu number.
 */
function cpu:long () %{ /* pure */ /* unprivileged */
	THIS->__retvalue = smp_processor_id();
%}

/**
 * sfunction pp - Return the probe point associated with the currently running probe handler,
 * including alias and wildcard expansion effects
 * Context:
 * The current probe point.
 */
function pp:string () %{ /* pure */ /* unprivileged */
	strlcpy (THIS->__retvalue, CONTEXT->probe_point, MAXSTRINGLEN);
%}

/**
 * sfunction registers_valid - Determines validity of register() and u_register() in current context.
 *
 *  Return 1 if register() and u_register() can be used
 *  in the current context, or 0 otherwise.
 *  For example, registers_valid() returns 0
 *  when called from a begin or end probe.
 */
function registers_valid:long () %{ /* pure */ /* unprivileged */
	THIS->__retvalue = (CONTEXT->regs != NULL);
%}

/**
 * sfunction user_mode - Determines if probe point occurs in user-mode.
 *
 * Return 1 if the probe point occurred in user-mode.
 */
function user_mode:long () %{ /* pure */ /* unprivileged */
  if (CONTEXT->regs) {
#if defined(__i386__) || defined(__x86_64__)
     THIS->__retvalue = (uint64_t) user_mode_vm (CONTEXT->regs);
#else
    THIS->__retvalue = (uint64_t) user_mode (CONTEXT->regs);
#endif
  } else {
    THIS->__retvalue = 0;
  }
%}

/**
 * sfunction is_return - Whether the current probe context is a return probe.
 *
 * Description: Returns 1 if the current probe context is a return probe,
 * returns 0 otherwise.
 */
function is_return:long () %{ /* pure */
	if (CONTEXT->pi)
		THIS->__retvalue = 1;
	else
		THIS->__retvalue = 0;
%}

/**
 * sfunction target - Return the process ID of the target process.
 */
function target:long () %{ /* pure */ /* unprivileged */
        THIS->__retvalue = _stp_target;
%}

/**
 * sfunction module_name - The module name of the current script.
 *
 * Returns the name of the stap module. Either generated randomly
 * (stap_[0-9a-f]+_[0-9a-f]+) or set by stap -m <module_name>.
 */
function module_name:string () %{ /* pure */ /* unprivileged */
	strlcpy(THIS->__retvalue, THIS_MODULE->name, MAXSTRINGLEN);
%}

/**
 * sfunction stp_pid - The process id of the stapio process.
 *
 * Returns the process id of the stapio process that launched
 * this script.
 */
function stp_pid:long () %{ /* pure */
        THIS->__retvalue = _stp_pid;
%}

/**
 * sfunction stack_size - Return the size of the kernel stack.
 */
function stack_size:long () %{ /* pure */
        THIS->__retvalue = THREAD_SIZE;
%}

/**
 * sfunction stack_used - Returns the amount of kernel stack used.
 *
 * Determines how many bytes are currently used in the kernel stack.
 */
function stack_used:long () %{ /* pure */
	char a;
        THIS->__retvalue = THREAD_SIZE - ((long)&a & (THREAD_SIZE-1));
%}

/**
 * sfunction stack_unused - Returns the amount of kernel stack currently available.
 *
 * Determines how many bytes are currently available in the kernel stack.
 */
function stack_unused:long () %{ /* pure */
	char a;
        THIS->__retvalue = (long)&a & (THREAD_SIZE-1);
%}

/**
 * sfunction uaddr - User space address of current running task. EXPERIMENTAL.
 *
 * Description: Returns the address in userspace that the current
 * task was at when the probe occurred. When the current running task
 * isn't a user space thread, or the address cannot be found, zero
 * is returned. Can be used to see where the current task is combined
 * with usymname() or symdata(). Often the task will be in the VDSO
 * where it entered the kernel. FIXME - need VDSO tracking support #10080.
 */
function uaddr:long () %{ /* pure */ /* unprivileged */
  int64_t addr = 0;
  assert_is_myproc();
  if (current->mm)
    {
      struct pt_regs *uregs;
      uregs = task_pt_regs(current);
      if (uregs)
        addr = (int64_t) REG_IP(uregs);
    }
  THIS->__retvalue = addr;
%}

/**
 * sfunction cmdline_args - Fetch command line arguments from current process
 *
 * @n: First argument to get (zero is the command itself)
 * @m: Last argument to get (or minus one for all arguments after n)
 * @delim: String to use to delimit arguments when more than one.
 *
 * Description: Returns arguments from the current process starting
 * with argument number n, up to argument m. If there are less than n
 * arguments, or the arguments cannot be retrieved from the current
 * process, the empty string is returned. If m is smaller than n then
 * all arguments starting from argument n are returned. Argument zero
 * is traditionally the command itself.
 */
function cmdline_args:string(n:long, m:long, delim:string)
{
  args = "";
  mm = @cast(task_current(), "task_struct", "kernel<linux/sched.h>")->mm;
  if (mm)
    {
      arg_start = @cast(mm, "mm_struct", "kernel<linux/sched.h>")->arg_start;
      arg_end = @cast(mm, "mm_struct", "kernel<linux/sched.h>")->arg_end;
      if (arg_start != 0 && arg_end != 0)
        {
          nr = 0;
          len = arg_end - arg_start;
          arg = user_string2(arg_start, "");
          while (arg != "" && len > 0)
            {
              if (nr == n)
                args = arg;
              else if (nr > n)
                args .= delim . arg;

              arg_len = strlen(arg);
              arg_start += arg_len + 1;
              len -= arg_len + 1;
              if (len > 0 && nr != m)
                arg = user_string2(arg_start, "");
              else
                arg = "";
              nr++;
            }
        }
    }
  return args;
}

/**
 * sfunction cmdline_arg - Fetch a command line argument.
 *
 * @n: Argument to get (zero is the command itself)
 *
 * Description: Returns argument the requested argument from the
 * current process or the empty string when there are not that many
 * arguments or there is a problem retrieving the argument. Argument
 * zero is traditionally the command itself.
 */
function cmdline_arg:string(n:long)
{
  return cmdline_args(n, n, "");
}

/**
 * sfunction cmdline_str - Fetch all command line arguments from current process
 *
 * Description: Returns all arguments from the current process
 * delimited by spaces. Returns the empty string when the arguments
 * cannot be retrieved.
 */
function cmdline_str:string()
{
  return cmdline_args(0, -1, " ");
}