// Process memory query and utility functions.
// Copyright (C) 2009 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>
// Process memory query and utility functions provide information about
// the memory usage of the current application. These functions provide
// information about the full size, resident, shared, code and data used
// by the current process. And provide utility functions to query the
// page size of the current architecture and create human readable string
// representations of bytes and pages used.
// </tapsetdescription>

%{
/* PF_BORROWED_MM got renamed to PF_KTHREAD with same semantics somewhere. */
#ifdef PF_BORROWED_MM
#define _STP_PF_KTHREAD PF_BORROWED_MM
#else
#define _STP_PF_KTHREAD PF_KTHREAD
#endif
  /* Returns the mm for the current proc. Slightly paranoid. Only returns
     if the task isn't starting, exiting or (coopted by) a kernel thread. */
  static struct mm_struct *_stp_proc_mm(void)
  {
    if (current->flags & (_STP_PF_KTHREAD | PF_EXITING | PF_STARTING))
      return NULL;
    return current->mm;
  }
%}

/**
 * sfunction proc_mem_size - Total program virtual memory size in pages.
 *
 * Description: Returns the total virtual memory size in pages of the
 * current process, or zero when there is no current process or the
 * number of pages couldn't be retrieved.
 */
function proc_mem_size:long ()
%{ /* pure */ /* unprivileged */
   struct mm_struct *mm = _stp_proc_mm ();
   if (mm)
     THIS->__retvalue = mm->total_vm;
   else
     THIS->__retvalue = 0;
%}

/**
 * sfunction proc_mem_rss - Program resident set size in pages.
 *
 * Description: Returns the resident set size in pages of the current
 * process, or zero when there is no current process or the number of
 * pages couldn't be retrieved.
 */
function proc_mem_rss:long ()
%{ /* pure */ /* unprivileged */
   struct mm_struct *mm = _stp_proc_mm ();
   if (mm)
     THIS->__retvalue = (get_mm_counter(mm, file_rss)
                         + get_mm_counter(mm, anon_rss));
   else
     THIS->__retvalue = 0;
%}

/**
 * sfunction proc_mem_shr - Program shared pages (from shared mappings).
 *
 * Description: Returns the shared pages (from shared mappings) of the
 * current process, or zero when there is no current process or the
 * number of pages couldn't be retrieved.
 */
function proc_mem_shr:long ()
%{ /* pure */ /* unprivileged */
   struct mm_struct *mm = _stp_proc_mm ();
   if (mm)
     THIS->__retvalue = get_mm_counter(mm, file_rss);
   else
     THIS->__retvalue = 0;
%}

/**
 * sfunction proc_mem_txt - Program text (code) size in pages.
 *
 * Description: Returns the current process text (code) size in pages,
 * or zero when there is no current process or the number of pages
 * couldn't be retrieved.
 */
function proc_mem_txt:long ()
%{ /* pure */ /* unprivileged */
   struct mm_struct *mm = _stp_proc_mm ();
   if (mm)
     THIS->__retvalue = (PAGE_ALIGN(mm->end_code)
                         - (mm->start_code & PAGE_MASK)) >> PAGE_SHIFT;
   else
     THIS->__retvalue = 0;
%}

/**
 * sfunction proc_mem_data - Program data size (data + stack) in pages.
 *
 * Description: Returns the current process data size (data + stack)
 * in pages, or zero when there is no current process or the number of
 * pages couldn't be retrieved.
 */
function proc_mem_data:long ()
%{ /* pure */ /* unprivileged */
   struct mm_struct *mm = _stp_proc_mm ();
   if (mm)
     THIS->__retvalue = mm->total_vm - mm->shared_vm;
   else
     THIS->__retvalue = 0;
%}

/**
 * sfunction mem_page_size - Number of bytes in a page for this architecture.
 */
function mem_page_size:long ()
%{ /* pure */ /* unprivileged */
   THIS->__retvalue = PAGE_SIZE;
%}

// Return a 5 character wide string " x.yyp", " xx.yp", " xxxp", "xxxxp".
function _stp_number_to_string_postfix:string (x:long, y:long, p:string)
{
  if (x < 10)
    return sprintf("%d.%.2d%s", x, y * 100 / 1024, p);
  if (x < 100)
    return sprintf("%2d.%d%s", x, y * 10 / 1024, p);
  return sprintf("%4d%s", x, p);
}

/**
 * sfunction bytes_to_string - Human readable string for given bytes.
 * @bytes: Number of bytes to translate.
 *
 * Description: Returns a string representing the number of bytes (up
 * to 1024 bytes), the number of kilobytes (when less than 1024K)
 * postfixed by 'K', the number of megabytes (when less than 1024M)
 * postfixed by 'M' or the number of gigabytes postfixed by 'G'. If
 * representing K, M or G, and the number is amount is less than 100,
 * it includes a '.' plus the remainer. The returned string will be 5
 * characters wide (padding with whitespace at the front) unless
 * negative or representing more than 9999G bytes.
 */
function bytes_to_string:string (bytes:long)
{
  if (bytes < 1024)
    return sprintf("%5d", bytes);

  remain = bytes % 1024;
  bytes = bytes / 1024;
  if (bytes < 1024)
    return _stp_number_to_string_postfix(bytes, remain, "K");

  remain = bytes % 1024;
  bytes = bytes / 1024;
  if (bytes < 1024)
    return _stp_number_to_string_postfix(bytes, remain, "M");

  remain = bytes % 1024;
  bytes = bytes / 1024;
    return _stp_number_to_string_postfix(bytes, remain, "G");
}

/**
 * sfunction pages_to_string - Turns pages into a human readable string.
 * @pages: Number of pages to translate.
 *
 * Description: Multiplies pages by page_size() to get the number of
 * bytes and returns the result of bytes_to_string().
 */
function pages_to_string:string (pages:long)
{
  bytes = pages * mem_page_size();
  return bytes_to_string (bytes);
}

/**
 * sfunction proc_mem_string - Human readable string of current proc memory usage.
 *
 * Description: Returns a human readable string showing the size, rss,
 * shr, txt and data of the memory used by the current process.
 * For example "size: 301m, rss: 11m, shr: 8m, txt: 52k, data: 2248k".
 */
function proc_mem_string:string ()
{
  return sprintf ("size: %s, rss: %s, shr: %s, txt: %s, data: %s",
                  pages_to_string(proc_mem_size()),
                  pages_to_string(proc_mem_rss()),
                  pages_to_string(proc_mem_shr()),
                  pages_to_string(proc_mem_txt()),
                  pages_to_string(proc_mem_data()));
}