📄 fork.c
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<!doctype html public "-//W3C//DTD HTML 3.2//EN"><html><head><title>Linux/kernel/fork.c</title><meta http-equiv=Content-Type content="text/html; charset=gb2312"><base href="http://oldlinux.org/lxr/http/"></head><body bgcolor=white><div align=center> [<b><i>源代码浏览</i></b>] [<a href="diff/kernel/fork.c">区别标定</a>] [<a href="ident">标识符搜索</a>] [<a href="search">文本搜索</a>] [<a href="find">文件搜索</a>]</div><h1 align=center> <a href="http:/"> OldLinux</a> <a href="http:blurb.html"> 交叉引用</a><br> <a href="source/">Linux</a>/<a href="source/kernel/">kernel</a>/<a href="source/kernel/fork.c">fork.c</a></h1><div align=center> <b>版本:</b> [<a href="source/kernel/fork.c?v=1.0">1.0</a>] [<a href="source/kernel/fork.c?v=0.99.11">0.99.11</a>] [<a href="source/kernel/fork.c?v=0.99">0.99</a>] [<a href="source/kernel/fork.c?v=0.97">0.97</a>] [<a href="source/kernel/fork.c?v=0.96a">0.96a</a>] [<a href="source/kernel/fork.c?v=0.95">0.95</a>] [<a href="source/kernel/fork.c?v=0.12">0.12</a>] [<b><i>0.11</i></b>] [<a href="source/kernel/fork.c?v=0.01">0.01</a>] <br> <b>体系结构:</b> [<b><i>i386</i></b>] <br></div><hr><pre> <a name=L1 href="source/kernel/fork.c#L1">1</a> <b><i>/*</i></b> <a name=L2 href="source/kernel/fork.c#L2">2</a> <b><i> * linux/kernel/fork.c</i></b> <a name=L3 href="source/kernel/fork.c#L3">3</a> <b><i> *</i></b> <a name=L4 href="source/kernel/fork.c#L4">4</a> <b><i> * (C) 1991 Linus Torvalds</i></b> <a name=L5 href="source/kernel/fork.c#L5">5</a> <b><i> */</i></b> <a name=L6 href="source/kernel/fork.c#L6">6</a> <a name=L7 href="source/kernel/fork.c#L7">7</a> <b><i>/*</i></b> <a name=L8 href="source/kernel/fork.c#L8">8</a> <b><i> * 'fork.c' contains the help-routines for the 'fork' system call</i></b> <a name=L9 href="source/kernel/fork.c#L9">9</a> <b><i> * (see also system_call.s), and some misc functions ('verify_area').</i></b> <a name=L10 href="source/kernel/fork.c#L10">10</a> <b><i> * Fork is rather simple, once you get the hang of it, but the memory</i></b> <a name=L11 href="source/kernel/fork.c#L11">11</a> <b><i> * management can be a bitch. See 'mm/mm.c': 'copy_page_tables()'</i></b> <a name=L12 href="source/kernel/fork.c#L12">12</a> <b><i> */</i></b> <a name=L13 href="source/kernel/fork.c#L13">13</a> #include <errno.h> <a name=L14 href="source/kernel/fork.c#L14">14</a> <a name=L15 href="source/kernel/fork.c#L15">15</a> #include <linux/sched.h> <a name=L16 href="source/kernel/fork.c#L16">16</a> #include <linux/kernel.h> <a name=L17 href="source/kernel/fork.c#L17">17</a> #include <asm/segment.h> <a name=L18 href="source/kernel/fork.c#L18">18</a> #include <asm/system.h> <a name=L19 href="source/kernel/fork.c#L19">19</a> <a name=L20 href="source/kernel/fork.c#L20">20</a> extern void <a href="ident?i=write_verify">write_verify</a>(unsigned long address); <a name=L21 href="source/kernel/fork.c#L21">21</a> <a name=L22 href="source/kernel/fork.c#L22">22</a> long <a href="ident?i=last_pid">last_pid</a>=0; <a name=L23 href="source/kernel/fork.c#L23">23</a> <a name=L24 href="source/kernel/fork.c#L24">24</a> void <a href="ident?i=verify_area">verify_area</a>(void * addr,int size) <a name=L25 href="source/kernel/fork.c#L25">25</a> { <a name=L26 href="source/kernel/fork.c#L26">26</a> unsigned long start; <a name=L27 href="source/kernel/fork.c#L27">27</a> <a name=L28 href="source/kernel/fork.c#L28">28</a> start = (unsigned long) addr; <a name=L29 href="source/kernel/fork.c#L29">29</a> size += start & 0xfff; <a name=L30 href="source/kernel/fork.c#L30">30</a> start &= 0xfffff000; <a name=L31 href="source/kernel/fork.c#L31">31</a> start += <a href="ident?i=get_base">get_base</a>(<a href="ident?i=current">current</a>->ldt[2]); <a name=L32 href="source/kernel/fork.c#L32">32</a> while (size>0) { <a name=L33 href="source/kernel/fork.c#L33">33</a> size -= 4096; <a name=L34 href="source/kernel/fork.c#L34">34</a> <a href="ident?i=write_verify">write_verify</a>(start); <a name=L35 href="source/kernel/fork.c#L35">35</a> start += 4096; <a name=L36 href="source/kernel/fork.c#L36">36</a> } <a name=L37 href="source/kernel/fork.c#L37">37</a> } <a name=L38 href="source/kernel/fork.c#L38">38</a> <a name=L39 href="source/kernel/fork.c#L39">39</a> int <a href="ident?i=copy_mem">copy_mem</a>(int nr,struct <a href="ident?i=task_struct">task_struct</a> * p) <a name=L40 href="source/kernel/fork.c#L40">40</a> { <a name=L41 href="source/kernel/fork.c#L41">41</a> unsigned long old_data_base,new_data_base,data_limit; <a name=L42 href="source/kernel/fork.c#L42">42</a> unsigned long old_code_base,new_code_base,code_limit; <a name=L43 href="source/kernel/fork.c#L43">43</a> <a name=L44 href="source/kernel/fork.c#L44">44</a> code_limit=<a href="ident?i=get_limit">get_limit</a>(0x0f); <a name=L45 href="source/kernel/fork.c#L45">45</a> data_limit=<a href="ident?i=get_limit">get_limit</a>(0x17); <a name=L46 href="source/kernel/fork.c#L46">46</a> old_code_base = <a href="ident?i=get_base">get_base</a>(<a href="ident?i=current">current</a>->ldt[1]); <a name=L47 href="source/kernel/fork.c#L47">47</a> old_data_base = <a href="ident?i=get_base">get_base</a>(<a href="ident?i=current">current</a>->ldt[2]); <a name=L48 href="source/kernel/fork.c#L48">48</a> if (old_data_base != old_code_base) <a name=L49 href="source/kernel/fork.c#L49">49</a> <a href="ident?i=panic">panic</a>(<i>"We don't support separate I&D"</i>); <a name=L50 href="source/kernel/fork.c#L50">50</a> if (data_limit < code_limit) <a name=L51 href="source/kernel/fork.c#L51">51</a> <a href="ident?i=panic">panic</a>(<i>"Bad data_limit"</i>); <a name=L52 href="source/kernel/fork.c#L52">52</a> new_data_base = new_code_base = nr * 0x4000000; <a name=L53 href="source/kernel/fork.c#L53">53</a> p->start_code = new_code_base; <a name=L54 href="source/kernel/fork.c#L54">54</a> <a href="ident?i=set_base">set_base</a>(p->ldt[1],new_code_base); <a name=L55 href="source/kernel/fork.c#L55">55</a> <a href="ident?i=set_base">set_base</a>(p->ldt[2],new_data_base); <a name=L56 href="source/kernel/fork.c#L56">56</a> if (<a href="ident?i=copy_page_tables">copy_page_tables</a>(old_data_base,new_data_base,data_limit)) { <a name=L57 href="source/kernel/fork.c#L57">57</a> <a href="ident?i=free_page_tables">free_page_tables</a>(new_data_base,data_limit); <a name=L58 href="source/kernel/fork.c#L58">58</a> return -<a href="ident?i=ENOMEM">ENOMEM</a>; <a name=L59 href="source/kernel/fork.c#L59">59</a> } <a name=L60 href="source/kernel/fork.c#L60">60</a> return 0; <a name=L61 href="source/kernel/fork.c#L61">61</a> } <a name=L62 href="source/kernel/fork.c#L62">62</a> <a name=L63 href="source/kernel/fork.c#L63">63</a> <b><i>/*</i></b> <a name=L64 href="source/kernel/fork.c#L64">64</a> <b><i> * Ok, this is the main fork-routine. It copies the system process</i></b>⌨️ 快捷键说明
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