/proc/N/maps 信息是如何生成的？【转】

/proc/N/maps 信息是如何生成的？【转】
转自：https://blog.csdn.net/zhoukangli/article/details/53363275?utm_medium=distribute.pc_relevant_bbs_down.none-task-blog-baidujs-1.nonecase&depth_1-utm_source=distribute.pc_relevant_bbs_down.none-task-blog-baidujs-1.nonecase

以进程1为例，查看proc长什么样子？
1. 127|shell@tiny4412:/proc/1 # ls -l
2. dr-xr-xr-x root root 2014-01-01 12:07 attr
3. -r-------- root root 0 2014-01-01 12:07 auxv
4. -r--r--r-- root root 0 2014-01-01 12:07 cgroup
5. --w------- root root 0 2014-01-01 12:07 clear_refs
6. -r--r--r-- root root 0 2014-01-01 12:00 cmdline
7. -rw-r--r-- root root 0 2014-01-01 12:07 comm
8. -rw-r--r-- root root 0 2014-01-01 12:07 coredump_filter
9. lrwxrwxrwx root root 2014-01-01 12:07 cwd -> /
10. -r-------- root root 0 2014-01-01 12:07 environ
11. lrwxrwxrwx root root 2014-01-01 12:07 exe -> /init
12. dr-x------ root root 2014-01-01 12:07 fd
13. dr-x------ root root 2014-01-01 12:07 fdinfo
14. -r--r--r-- root root 0 2014-01-01 12:07 limits
15. -rw-r--r-- root root 0 2014-01-01 12:07 loginuid
16. -r--r--r-- root root 0 2014-01-01 12:07 maps ----------->比较关心映射关系是如何生成的
17. -rw------- root root 0 2014-01-01 12:07 mem
18. -r--r--r-- root root 0 2014-01-01 12:07 mountinfo
19. -r--r--r-- root root 0 2014-01-01 12:07 mounts
20. -r-------- root root 0 2014-01-01 12:07 mountstats
21. dr-xr-xr-x root root 2014-01-01 12:00 net
22. dr-x--x--x root root 2014-01-01 12:07 ns
23. -rw-r--r-- root root 0 2014-01-01 12:07 oom_adj
24. -r--r--r-- root root 0 2014-01-01 12:07 oom_killed
25. -r--r--r-- root root 0 2014-01-01 12:07 oom_score
26. -rw-r--r-- root root 0 2014-01-01 12:00 oom_score_adj
27. -r--r--r-- root root 0 2014-01-01 12:07 pagemap
28. -r--r--r-- root root 0 2014-01-01 12:07 personality
29. lrwxrwxrwx root root 2014-01-01 12:07 root -> /
30. -rw-r--r-- root root 0 2014-01-01 12:07 sched
31. -r--r--r-- root root 0 2014-01-01 12:07 schedstat
32. -r--r--r-- root root 0 2014-01-01 12:07 sessionid
33. -r--r--r-- root root 0 2014-01-01 12:00 smaps
34. -r--r--r-- root root 0 2014-01-01 12:07 stack
35. -r--r--r-- root root 0 2014-01-01 12:00 stat
36. -r--r--r-- root root 0 2014-01-01 12:07 statm
37. -r--r--r-- root root 0 2014-01-01 12:07 status
38. dr-xr-xr-x root root 2014-01-01 12:00 task
39. -r--r--r-- root root 0 2014-01-01 12:07 wchan
查看详细映射关系：
1. shell@tiny4412:/proc/1 # cat maps
2. 00008000-00049000 r-xp 00000000 00:01 1422 /init
3. 0004a000-0004c000 r--p 00041000 00:01 1422 /init
4. 0004c000-0004f000 rw-p 00043000 00:01 1422 /init
5. 0004f000-00052000 rw-p 00000000 00:00 0 [heap]
6. 40017000-40019000 rw-p 00000000 00:00 0
7. 40072000-40073000 r--p 00000000 00:00 0
8. 40090000-400b0000 rw-s 00000000 00:0c 2056 /dev/__properties__
9. 400b2000-400b3000 rw-p 00000000 00:00 0
10. 40100000-40301000 rw-p 00000000 00:00 0
11. becd2000-becf3000 rw-p 00000000 00:00 0 [stack]
12. ffff0000-ffff1000 r-xp 00000000 00:00 0 [vectors]
14. 根据源码的解析：
15. vm_area_struct
16. unsigned long vm_start; /* Our start address within vm_mm. */
17. unsigned long vm_end; /* The first byte after our end address
18. within vm_mm. */
19. unsigned long vm_flags; /* Flags, see mm.h. */ 分别是读，写，共享/私有
20. /* Information about our backing store: */
21. unsigned long vm_pgoff; /* Offset (within vm_file) in PAGE_SIZE 页偏移
22. units, *not* PAGE_CACHE_SIZE */
24. vma->vm_file->f_path.dentry->d_inode-->i_sb->s_dev; 主设备号，次设备号
1. vma->vm_file->f_path.dentry->d_inode-->i_ino inode 号
2. 最后就是 /*
3. * Print the dentry name for named mappings, and a
4. * special [heap] marker for the heap:
5. */调用文件路径
linux源码位置及主要宏

android/linux-3.0.86/fs/proc/base.c
1. static const struct pid_entry tid_base_stuff[] = {
2. DIR("fd", S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations),
3. DIR("fdinfo", S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations),
4. DIR("ns", S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations),
5. REG("environ", S_IRUSR, proc_environ_operations),
6. INF("auxv", S_IRUSR, proc_pid_auxv),
7. ONE("status", S_IRUGO, proc_pid_status),
8. ONE("personality", S_IRUGO, proc_pid_personality),
9. INF("limits", S_IRUGO, proc_pid_limits),
10. #ifdef CONFIG_SCHED_DEBUG
11. REG("sched", S_IRUGO|S_IWUSR, proc_pid_sched_operations),
12. #endif
13. REG("comm", S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
14. #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
15. INF("syscall", S_IRUGO, proc_pid_syscall),
16. #endif
17. INF("cmdline", S_IRUGO, proc_pid_cmdline),
18. ONE("stat", S_IRUGO, proc_tid_stat),
19. ONE("statm", S_IRUGO, proc_pid_statm),
20. REG("maps", S_IRUGO, proc_maps_operations), -------------------->关注映射
21. #ifdef CONFIG_NUMA
22. REG("numa_maps", S_IRUGO, proc_numa_maps_operations),
23. #endif
24. REG("mem", S_IRUSR|S_IWUSR, proc_mem_operations),
25. LNK("cwd", proc_cwd_link),
26. LNK("root", proc_root_link),
27. LNK("exe", proc_exe_link),
28. REG("mounts", S_IRUGO, proc_mounts_operations),
29. REG("mountinfo", S_IRUGO, proc_mountinfo_operations),
30. #ifdef CONFIG_PROC_PAGE_MONITOR
31. REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
32. REG("smaps", S_IRUGO, proc_smaps_operations),
33. REG("pagemap", S_IRUGO, proc_pagemap_operations),
34. #endif
35. #ifdef CONFIG_SECURITY
36. DIR("attr", S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
37. #endif
38. #ifdef CONFIG_KALLSYMS
39. INF("wchan", S_IRUGO, proc_pid_wchan),
40. #endif
41. #ifdef CONFIG_STACKTRACE
42. ONE("stack", S_IRUGO, proc_pid_stack),
43. #endif
44. #ifdef CONFIG_SCHEDSTATS
45. INF("schedstat", S_IRUGO, proc_pid_schedstat),
46. #endif
47. #ifdef CONFIG_LATENCYTOP
48. REG("latency", S_IRUGO, proc_lstats_operations),
49. #endif
50. #ifdef CONFIG_PROC_PID_CPUSET
51. REG("cpuset", S_IRUGO, proc_cpuset_operations),
52. #endif
53. #ifdef CONFIG_CGROUPS
54. REG("cgroup", S_IRUGO, proc_cgroup_operations),
55. #endif
56. INF("oom_score", S_IRUGO, proc_oom_score),
57. REG("oom_adj", S_IRUGO|S_IWUSR, proc_oom_adjust_operations),
58. REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
59. #ifdef CONFIG_ANDROID
60. REG("oom_killed", S_IRUGO, proc_oom_killed_operations),
61. #endif
62. #ifdef CONFIG_AUDITSYSCALL
63. REG("loginuid", S_IWUSR|S_IRUGO, proc_loginuid_operations),
64. REG("sessionid", S_IRUGO, proc_sessionid_operations),
65. #endif
66. #ifdef CONFIG_FAULT_INJECTION
67. REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
68. #endif
69. #ifdef CONFIG_TASK_IO_ACCOUNTING
70. INF("io", S_IRUSR, proc_tid_io_accounting),
71. #endif
72. #ifdef CONFIG_HARDWALL
73. INF("hardwall", S_IRUGO, proc_pid_hardwall),
74. #endif
75. };
pid_entry 是一个什么样的结构体？

struct pid_entry {
   char *name; -------->这个应该就是proc目录下面对应文件名或者文件夹名称
   int len;
   mode_t mode; --------->权限
   const struct inode_operations *iop; --------------->与inode 对应，我们在操作文件的时候，先找到文件名，然后通过文件名及路径找到inode,再通过inode找到它的操作方法
   const struct file_operations *fop;
   union proc_op op;
};

#define NOD(NAME, MODE, IOP, FOP, OP) {
   .name = (NAME),
   .len = sizeof(NAME) - 1,
   .mode = MODE,
   .iop = IOP,
   .fop = FOP,
   .op   = OP,
}

#define DIR(NAME, MODE, iops, fops)
   NOD(NAME, (S_IFDIR|(MODE)), &iops, &fops, {} ) ----------->对应目录信息的填充宏

例子：    DIR("fd",        S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations)

dr-x------ root     root              2014-01-01 12:07 fd

#define LNK(NAME, get_link)
   NOD(NAME, (S_IFLNK|S_IRWXUGO),
       &proc_pid_link_inode_operations, NULL,       ----->链接文件
       { .proc_get_link = get_link } ) ------------------------>设置的是链接信息

例子：    LNK("cwd",       proc_cwd_link),
   LNK("root",      proc_root_link),
   LNK("exe",       proc_exe_link),
lrwxrwxrwx root     root              2014-01-01 12:07 cwd -> /   ----->当前工作目录

#define REG(NAME, MODE, fops)
   NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {})--------->普通文件,只包含file_operation，因为仅仅是一个文件

REG("maps",      S_IRUGO, proc_maps_operations),

const struct file_operations proc_maps_operations = {
   .open       = maps_open,
   .read       = seq_read,              ------------------>和序列文件有关系
   .llseek       = seq_lseek,
   .release   = seq_release_private,
};

#define INF(NAME, MODE, read)
   NOD(NAME, (S_IFREG|(MODE)),
       NULL, &proc_info_file_operations,

        { .proc_read = read } )

static const struct file_operations proc_info_file_operations = {-------->支持信息读取
   .read       = proc_info_read,
   .llseek       = generic_file_llseek,
};

例子：    INF("cmdline",   S_IRUGO, proc_pid_cmdline),
-r--r--r-- root     root            0 2014-01-01 12:00 cmdline

#define ONE(NAME, MODE, show)               --------->单个文件？什么意思？
   NOD(NAME, (S_IFREG|(MODE)),
       NULL, &proc_single_file_operations,
       { .proc_show = show } )-------->填充的是proc_show，可以看出ONE，INFO，LINK等的其中一个差别就是设置prop_op 不一样，另外一个是file_operation不一样

例子：
#ifdef CONFIG_STACKTRACE
   ONE("stack",      S_IRUGO, proc_pid_stack),
#endif

-r--r--r-- root     root            0 2014-01-01 12:07 stack 只读信息

/* ANDROID is for special files in /proc. */ --------------------------->还冒出来一个android相关的
#define ANDROID(NAME, MODE, OTYPE)
   NOD(NAME, (S_IFREG|(MODE)),
       &proc_##OTYPE##_inode_operations,
       &proc_##OTYPE##_operations, {})

例子：

    ANDROID("oom_adj",S_IRUGO|S_IWUSR, oom_adjust), ----------------->调整优先级，我们的service,activity 相关的进程分前端，后端优先级不一样会动态调整，不知道是不是通过这个调整的？有一个特别的地方是具体有写权限。

-rw-r--r-- root     root            0 2014-01-01 12:07 oom_adj

union proc_op {------------------------------------------------------------->联合体，同时只会存在一种可能。
   int (*proc_get_link)(struct inode *, struct path *);
   int (*proc_read)(struct task_struct *task, char *page);
   int (*proc_show)(struct seq_file *m,
       struct pid_namespace *ns, struct pid *pid,
       struct task_struct *task);
};

下面详细查看maps 相关的实现内容

代码位置：

android/linux-3.0.86/fs/proc/task_mmu.c
1. const struct file_operations proc_maps_operations = {
2. .open = maps_open,
3. .read = seq_read,
4. .llseek = seq_lseek,
5. .release = seq_release_private,
6. };
使用strace 跟踪一下cat maps 的执行情况：
1. 1|shell@tiny4412:/proc/1 # strace cat maps
2. execve("/system/bin/cat", ["cat", "maps"], [/* 24 vars */]) = 0
3. mprotect(0x401db000, 4096, PROT_READ) = 0
4. set_tid_address(0x401dced0) = 10588
5. set_tls(0x401dd10c, 0x401dd10c, 0x401dd10c, 0x401dcedc, 0x401dcec8) = 0
6. mmap2(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40027000
7. madvise(0x40027000, 8192, MADV_MERGEABLE) = -1 EINVAL (Invalid argument)
8. sigaltstack({ss_sp=0x40027000, ss_flags=0, ss_size=8192}, NULL) = 0
9. sigaction(SIGABRT, {0x401cea25, [], SA_RESTART|SA_SIGINFO|SA_ONSTACK}, NULL) = 0
10. sigaction(SIGBUS, {0x401cea25, [], SA_RESTART|SA_SIGINFO|SA_ONSTACK}, NULL) = 0
11. sigaction(SIGFPE, {0x401cea25, [], SA_RESTART|SA_SIGINFO|SA_ONSTACK}, NULL) = 0
12. sigaction(SIGILL, {0x401cea25, [], SA_RESTART|SA_SIGINFO|SA_ONSTACK}, NULL) = 0
13. sigaction(SIGPIPE, {0x401cea25, [], SA_RESTART|SA_SIGINFO|SA_ONSTACK}, NULL) = 0
14. sigaction(SIGSEGV, {0x401cea25, [], SA_RESTART|SA_SIGINFO|SA_ONSTACK}, NULL) = 0
15. sigaction(SIGSTKFLT, {0x401cea25, [], SA_RESTART|SA_SIGINFO|SA_ONSTACK}, NULL) = 0
16. sigaction(SIGTRAP, {0x401cea25, [], SA_RESTART|SA_SIGINFO|SA_ONSTACK}, NULL) = 0
17. mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 0, 0) = 0x4009e000
18. prctl(0x53564d41 /* PR_??? */, 0, 0x4009e000, 0x1000, 0x401d87ca) = -1 EINVAL (Invalid argument)
19. openat(AT_FDCWD, "/vendor/lib/libsigchain.so", O_RDONLY) = -1 ENOENT (No such file or directory)
20. openat(AT_FDCWD, "/system/lib/libsigchain.so", O_RDONLY) = 3
21. fstat64(3, {st_mode=S_IFREG|0644, st_size=5352, ...}) = 0
22. read(3, "177ELF1113(1004"..., 52) = 52
23. mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE, 3, 0) = 0x40100000
24. mmap2(NULL, 12288, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x401de000
25. mmap2(0x401de000, 2953, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED, 3, 0) = 0x401de000
26. mmap2(0x401df000, 4100, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0) = 0x401df000
27. openat(AT_FDCWD, "/vendor/lib/libc.so", O_RDONLY) = -1 ENOENT (No such file or directory)
28. openat(AT_FDCWD, "/system/lib/libc.so", O_RDONLY) = 4
29. fstat64(4, {st_mode=S_IFREG|0644, st_size=608820, ...}) = 0
30. read(4, "177ELF1113(1004"..., 52) = 52
31. mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE, 4, 0) = 0x40067000
32. mmap2(NULL, 483328, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40143000
33. mmap2(0x40143000, 414868, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED, 4, 0) = 0x40143000
34. mmap2(0x401aa000, 21808, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 4, 0x66000) = 0x401aa000
35. mmap2(0x401b0000, 36864, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x401b0000
36. mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 0, 0) = 0x40101000
37. prctl(0x53564d41 /* PR_??? */, 0, 0x40101000, 0x1000, 0x401d87ca) = -1 EINVAL (Invalid argument)
38. mprotect(0x401aa000, 12288, PROT_READ) = 0
39. munmap(0x40067000, 4096) = 0
40. close(4) = 0
41. openat(AT_FDCWD, "/vendor/lib/liblog.so", O_RDONLY) = -1 ENOENT (No such file or directory)
42. openat(AT_FDCWD, "/system/lib/liblog.so", O_RDONLY) = 4
43. fstat64(4, {st_mode=S_IFREG|0644, st_size=21744, ...}) = 0
44. read(4, "177ELF1113(1004"..., 52) = 52
45. mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE, 4, 0) = 0x40042000
46. mmap2(NULL, 28672, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x4006d000
47. mmap2(0x4006d000, 16860, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED, 4, 0) = 0x4006d000
48. mmap2(0x40072000, 4108, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 4, 0x4000) = 0x40072000
49. openat(AT_FDCWD, "/vendor/lib/libm.so", O_RDONLY) = -1 ENOENT (No such file or directory)
50. openat(AT_FDCWD, "/system/lib/libm.so", O_RDONLY) = 5
51. fstat64(5, {st_mode=S_IFREG|0644, st_size=95508, ...}) = 0
52. read(5, "177ELF1113(1004"..., 52) = 52
53. mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE, 5, 0) = 0x40074000
54. mmap2(NULL, 102400, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40122000
55. mmap2(0x40122000, 90404, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED, 5, 0) = 0x40122000
56. mmap2(0x40139000, 4204, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 5, 0x16000) = 0x40139000
57. mprotect(0x40139000, 4096, PROT_READ) = 0
58. munmap(0x40074000, 4096) = 0
59. close(5) = 0
60. openat(AT_FDCWD, "/vendor/lib/libstdc++.so", O_RDONLY) = -1 ENOENT (No such file or directory)
61. openat(AT_FDCWD, "/system/lib/libstdc++.so", O_RDONLY) = 5
62. fstat64(5, {st_mode=S_IFREG|0644, st_size=9396, ...}) = 0
63. read(5, "177ELF1113(1004"..., 52) = 52
64. mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE, 5, 0) = 0x40021000
65. mmap2(NULL, 16384, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40074000
66. mmap2(0x40074000, 5782, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED, 5, 0) = 0x40074000
67. mmap2(0x40076000, 4100, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 5, 0x1000) = 0x40076000
68. mprotect(0x40076000, 4096, PROT_READ) = 0
69. munmap(0x40021000, 4096) = 0
70. close(5) = 0
71. mprotect(0x40072000, 4096, PROT_READ) = 0
72. munmap(0x40042000, 4096) = 0
73. close(4) = 0
74. mprotect(0x401df000, 4096, PROT_READ) = 0
75. munmap(0x40100000, 4096) = 0
76. close(3) = 0
77. openat(AT_FDCWD, "/vendor/lib/libcrypto.so", O_RDONLY) = -1 ENOENT (No such file or directory)
78. openat(AT_FDCWD, "/system/lib/libcrypto.so", O_RDONLY) = 3
79. fstat64(3, {st_mode=S_IFREG|0644, st_size=1052960, ...}) = 0
80. read(3, "177ELF1113(1004"..., 52) = 52
81. mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE, 3, 0) = 0x4003a000
82. mmap2(NULL, 1064960, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x401e1000
83. mmap2(0x401e1000, 966164, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED, 3, 0) = 0x401e1000
84. mmap2(0x402ce000, 84864, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0xec000) = 0x402ce000
85. mmap2(0x402e3000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x402e3000
86. mprotect(0x402ce000, 61440, PROT_READ) = 0
87. munmap(0x4003a000, 4096) = 0
88. close(3) = 0
89. openat(AT_FDCWD, "/vendor/lib/libcutils.so", O_RDONLY) = -1 ENOENT (No such file or directory)
90. openat(AT_FDCWD, "/system/lib/libcutils.so", O_RDONLY) = 3
91. fstat64(3, {st_mode=S_IFREG|0644, st_size=46480, ...}) = 0
92. read(3, "177ELF1113(1004"..., 52) = 52
93. mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE, 3, 0) = 0x40098000
94. mmap2(NULL, 53248, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40102000
95. mmap2(0x40102000, 42896, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED, 3, 0) = 0x40102000
96. mmap2(0x4010d000, 4160, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0xa000) = 0x4010d000
97. mprotect(0x4010d000, 4096, PROT_READ) = 0
98. munmap(0x40098000, 4096) = 0
99. close(3) = 0
100. openat(AT_FDCWD, "/vendor/lib/libselinux.so", O_RDONLY) = -1 ENOENT (No such file or directory)
101. openat(AT_FDCWD, "/system/lib/libselinux.so", O_RDONLY) = 3
102. fstat64(3, {st_mode=S_IFREG|0644, st_size=50564, ...}) = 0
103. read(3, "177ELF1113(1004"..., 52) = 52
104. mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE, 3, 0) = 0x400dc000
105. mmap2(NULL, 57344, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x402e5000
106. mmap2(0x402e5000, 47462, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED, 3, 0) = 0x402e5000
107. mmap2(0x402f1000, 4144, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0xb000) = 0x402f1000
108. mprotect(0x402f1000, 4096, PROT_READ) = 0
109. munmap(0x400dc000, 4096) = 0
110. close(3) = 0
111. mprotect(0x400dd000, 4096, PROT_READ) = 0
112. openat(AT_FDCWD, "/dev/__properties__", O_RDONLY|O_NOFOLLOW) = 3--------------->打开文件
113. fcntl64(3, F_SETFD, FD_CLOEXEC) = 0
114. fstat64(3, {st_mode=S_IFREG|0444, st_size=131072, ...}) = 0
115. mmap2(NULL, 131072, PROT_READ, MAP_SHARED, 3, 0) = 0x402f3000
116. close(3) = 0
117. futex(0x401af5a8, FUTEX_WAKE_PRIVATE, 2147483647) = 0
118. mprotect(0x4009e000, 4096, PROT_READ|PROT_WRITE) = 0
119. mprotect(0x40101000, 4096, PROT_READ|PROT_WRITE) = 0
120. openat(AT_FDCWD, "/vendor/lib/libnetd_client.so", O_RDONLY) = -1 ENOENT (No such file or directory)
121. openat(AT_FDCWD, "/system/lib/libnetd_client.so", O_RDONLY) = 3
122. fstat64(3, {st_mode=S_IFREG|0644, st_size=9428, ...}) = 0
123. read(3, "177ELF1113(1004"..., 52) = 52
124. mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE, 3, 0) = 0x400dc000
125. mmap2(NULL, 16384, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x4010f000
126. mmap2(0x4010f000, 3856, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED, 3, 0) = 0x4010f000
127. mmap2(0x40111000, 4100, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x1000) = 0x40111000
128. mprotect(0x40111000, 4096, PROT_READ) = 0
129. munmap(0x400dc000, 4096) = 0
130. close(3) = 0
131. mprotect(0x4009e000, 4096, PROT_READ) = 0
132. mprotect(0x40101000, 4096, PROT_READ) = 0
133. mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 0, 0) = 0x40046000
134. prctl(0x53564d41 /* PR_??? */, 0, 0x40046000, 0x1000, 0x401d87ca) = -1 EINVAL (Invalid argument)
135. futex(0x401b0dd4, FUTEX_WAKE_PRIVATE, 2147483647) = 0
136. mprotect(0x4009e000, 4096, PROT_READ|PROT_WRITE) = 0
137. mprotect(0x40101000, 4096, PROT_READ|PROT_WRITE) = 0
138. mprotect(0x4009e000, 4096, PROT_READ|PROT_WRITE) = 0
139. mprotect(0x40101000, 4096, PROT_READ|PROT_WRITE) = 0
140. mprotect(0x4009e000, 4096, PROT_READ|PROT_WRITE) = 0
141. mprotect(0x40101000, 4096, PROT_READ|PROT_WRITE) = 0
142. mprotect(0x4009e000, 4096, PROT_READ|PROT_WRITE) = 0
143. mprotect(0x40101000, 4096, PROT_READ|PROT_WRITE) = 0
144. mprotect(0x4009e000, 4096, PROT_READ|PROT_WRITE) = 0
145. mprotect(0x40101000, 4096, PROT_READ|PROT_WRITE) = 0
146. mprotect(0x4009e000, 4096, PROT_READ|PROT_WRITE) = 0
147. mprotect(0x40101000, 4096, PROT_READ|PROT_WRITE) = 0
148. brk(0) = 0x41525000
149. mmap2(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40313000
150. madvise(0x40313000, 1048576, MADV_MERGEABLE) = -1 EINVAL (Invalid argument)
151. prctl(0x53564d41 /* PR_??? */, 0, 0x40313000, 0x100000, 0x401a1685) = -1 EINVAL (Invalid argument)
152. munmap(0x40313000, 1048576) = 0
153. mmap2(NULL, 2093056, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40313000
154. prctl(0x53564d41 /* PR_??? */, 0, 0x40313000, 0x1ff000, 0x401a1685) = -1 EINVAL (Invalid argument)
155. munmap(0x40313000, 970752) = 0
156. munmap(0x40500000, 73728) = 0
157. mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40100000
158. mprotect(0x40100000, 4096, PROT_READ) = 0
159. openat(AT_FDCWD, "/proc/stat", O_RDONLY) = 3 ----------------------->打开文件
160. fstat64(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
161. mmap2(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40500000
162. prctl(0x53564d41 /* PR_??? */, 0, 0x40500000, 0x100000, 0x401a1685) = -1 EINVAL (Invalid argument)
163. mprotect(0x40100000, 4096, PROT_READ|PROT_WRITE) = 0
164. mprotect(0x40100000, 4096, PROT_READ) = 0
165. read(3, "cpu 5457 1230 13251 421214 1598"..., 1024) = 1024
166. read(3, " 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0"..., 1024) = 212
167. read(3, "", 1024) = 0
168. close(3) = 0
169. mprotect(0x4009e000, 4096, PROT_READ|PROT_WRITE) = 0
170. mprotect(0x40101000, 4096, PROT_READ|PROT_WRITE) = 0
171. mprotect(0x4009e000, 4096, PROT_READ|PROT_WRITE) = 0
172. mprotect(0x40101000, 4096, PROT_READ|PROT_WRITE) = 0
173. statfs64("/sys/fs/selinux", 88, {f_type=0xf97cff8c, f_bsize=4096, f_blocks=0, f_bfree=0, f_bavail=0, f_files=0, f_ffree=0, f_fsid={0, 0}, f_namelen=255, f_frsize=4096, f_flags=4128}) = 0
174. mprotect(0x4009e000, 4096, PROT_READ|PROT_WRITE) = 0
175. mprotect(0x40101000, 4096, PROT_READ|PROT_WRITE) = 0
176. rt_sigprocmask(SIG_SETMASK, [HUP INT QUIT ABRT KILL USR1 USR2 PIPE ALRM TERM STKFLT CHLD CONT STOP TSTP TTIN TTOU URG XCPU XFSZ VTALRM PROF WINCH IO PWR SYS RTMIN], [], 8) = 0
177. sigaction(SIGILL, {0x402a3b6d, ~[ILL TRAP BUS FPE SEGV], 0}, {0x401cea25, [], SA_RESTART|SA_SIGINFO|SA_ONSTACK}) = 0
178. rt_sigprocmask(SIG_BLOCK, [], [HUP INT QUIT ABRT USR1 USR2 PIPE ALRM TERM STKFLT CHLD CONT TSTP TTIN TTOU URG XCPU XFSZ VTALRM PROF WINCH IO PWR SYS RTMIN], 8) = 0
179. --- SIGILL {si_signo=SIGILL, si_code=ILL_ILLOPC, si_addr=0x40223908} ---
180. rt_sigprocmask(SIG_SETMASK, [HUP INT QUIT ABRT USR1 USR2 PIPE ALRM TERM STKFLT CHLD CONT TSTP TTIN TTOU URG XCPU XFSZ VTALRM PROF WINCH IO PWR SYS RTMIN], [HUP INT QUIT ILL ABRT USR1 USR2 PIPE ALRM TERM 0
181. sigaction(SIGILL, {0x401cea25, [], SA_RESTART|SA_SIGINFO|SA_ONSTACK}, NULL) = 0
182. rt_sigprocmask(SIG_SETMASK, [], [HUP INT QUIT ABRT USR1 USR2 PIPE ALRM TERM STKFLT CHLD CONT TSTP TTIN TTOU URG XCPU XFSZ VTALRM PROF WINCH IO PWR SYS RTMIN], 8) = 0
183. mprotect(0x4009e000, 4096, PROT_READ|PROT_WRITE) = 0
184. mprotect(0x40101000, 4096, PROT_READ|PROT_WRITE) = 0
185. mprotect(0x4009e000, 4096, PROT_READ) = 0
186. mprotect(0x40101000, 4096, PROT_READ) = 0
187. mprotect(0x40100000, 4096, PROT_READ|PROT_WRITE) = 0
188. mprotect(0x40100000, 4096, PROT_READ) = 0
190. openat(AT_FDCWD, "maps", O_RDONLY) = 3 ----------->打开maps文件
191. ------------------------------------------------------------------------------------------------------------------------>这一块都是输出了
193. fstat64(1, {st_mode=S_IFCHR|0666, st_rdev=makedev(204, 64), ...}) = 0
194. read(3, "00008000-00049000 r-xp 00000000 "..., 4096) = 570
195. write(1, "00008000-00049000 r-xp 00000000 "..., 57000008000-00049000 r-xp 00000000 00:01 1422 /init
196. 0004a000-0004c000 r--p 00041000 00:01 1422 /init
197. 0004c000-0004f000 rw-p 00043000 00:01 1422 /init
198. 0004f000-00052000 rw-p 00000000 00:00 0 [heap]
199. 40017000-40019000 rw-p 00000000 00:00 0
200. 40072000-40073000 r--p 00000000 00:00 0
201. 40090000-400b0000 rw-s 00000000 00:0c 2056 /dev/__properties__
202. 400b2000-400b3000 rw-p 00000000 00:00 0
203. 40100000-40301000 rw-p 00000000 00:00 0
204. becd2000-becf3000 rw-p 00000000 00:00 0 [stack]
205. ffff0000-ffff1000 r-xp 00000000 00:00 0 [vectors]
206. ) = 570
207. read(3, "", 4096) = 0
208. close(3) = 0
209. close(1) = 0
210. mprotect(0x40100000, 4096, PROT_READ|PROT_WRITE) = 0
211. mprotect(0x40100000, 4096, PROT_READ) = 0
212. close(0) = 0
213. close(2) = 0
214. futex(0x401af5a0, FUTEX_WAKE_PRIVATE, 2147483647) = 0
215. mprotect(0x40100000, 4096, PROT_READ|PROT_WRITE) = 0
216. mprotect(0x40100000, 4096, PROT_READ) = 0
217. munmap(0x40100000, 4096) = 0
218. exit_group(0) = ?
219. +++ exited with 0 +++
跟踪源码，先看一下maps_open
1. static int maps_open(struct inode *inode, struct file *file)
2. {
3. return do_maps_open(inode, file, &proc_pid_maps_op); ----------->填充了proc_pid_maps_op的操作，序列文件的op
4. }
1. static const struct seq_operations proc_pid_maps_op = {
2. .start = m_start,
3. .next = m_next,
4. .stop = m_stop,
5. .show = show_map
6. };
1. static int do_maps_open(struct inode *inode, struct file *file,
2. const struct seq_operations *ops)
3. {
4. struct proc_maps_private *priv;
5. int ret = -ENOMEM;
6. priv = kzalloc(sizeof(*priv), GFP_KERNEL);--------->分配memory?
7. if (priv) {
8. priv->pid = proc_pid(inode);-------->通过inode获取pid信息
9. ret = seq_open(file, ops);------------->打开序列文件
10. if (!ret) {
11. struct seq_file *m = file->private_data;
12. m->private = priv;
13. } else {
14. kfree(priv);
15. }
16. }
17. return ret;
18. }
proc_maps_private 为何物？
1. struct proc_maps_private {
2. struct pid *pid;-------------------->仅仅一个pid并不简单，不能跟太深，会迷失...
3. struct task_struct *task;--------->进程相关的信息
4. #ifdef CONFIG_MMU
5. struct vm_area_struct *tail_vma;
6. #endif
7. };
1. static inline struct pid *proc_pid(struct inode *inode)
2. {
3. return PROC_I(inode)->pid;------------->根据inode可以找到对应的进程id
4. }
1. static inline struct proc_inode *PROC_I(const struct inode *inode)
2. {
3. return container_of(inode, struct proc_inode, vfs_inode);
4. }
通过inode 进而找到proc_inode，然后再找到pid
1. struct proc_inode {
2. struct pid *pid;--------------------->找到了....
3. int fd;
4. union proc_op op;
5. struct proc_dir_entry *pde;
6. struct ctl_table_header *sysctl;
7. struct ctl_table *sysctl_entry;
8. void *ns;
9. const struct proc_ns_operations *ns_ops;
10. struct inode vfs_inode;------------------->知道地之后，计算偏移，就可以找到pid了
11. };
序列文件？
1. int seq_open(struct file *file, const struct seq_operations *op)
2. {
3. struct seq_file *p = file->private_data; ---------->难道数据存储在file的private_data，什么时候第一次生成的呢？理论上该是在进程创建的时候。
5. if (!p) {
6. p = kmalloc(sizeof(*p), GFP_KERNEL);---------》如果为空，那么就分配一个，并将地址存放到file的似有空间里面。
7. if (!p)
8. return -ENOMEM;
9. file->private_data = p;
10. }
11. memset(p, 0, sizeof(*p));
12. mutex_init(&p->lock);
13. p->op = op;----------------------------->填充之前传进来的proc_pid_maps_op，即使是空的，也就是至少准备了一个seq_file
15. /*
16. * Wrappers around seq_open(e.g. swaps_open) need to be
17. * aware of this. If they set f_version themselves, they
18. * should call seq_open first and then set f_version.
19. */
20. file->f_version = 0;
22. /*
23. * seq_files support lseek() and pread(). They do not implement
24. * write() at all, but we clear FMODE_PWRITE here for historical
25. * reasons.
26. *
27. * If a client of seq_files a) implements file.write() and b) wishes to
28. * support pwrite() then that client will need to implement its own
29. * file.open() which calls seq_open() and then sets FMODE_PWRITE.
30. */
31. file->f_mode &= ~FMODE_PWRITE;
32. return 0;
33. }
看一下seq_file到底是什么样子？
1. struct seq_file {
2. char *buf;
3. size_t size;
4. size_t from;
5. size_t count;
6. loff_t index;
7. loff_t read_pos;
8. u64 version;
9. struct mutex lock;
10. const struct seq_operations *op;
11. void *private;
12. };
感觉就是一段buffer，然后增加了版本，代写哦啊，偏移位置，锁以及ops等信息

那么接下来应该是读取了？因为理论上应该是先open，然后读取的
1. ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
2. {
3. struct seq_file *m = file->private_data; -------------->不知道这个数据是不是空的啊？现在应该不是空的了，上面已经填充了...
4. size_t copied = 0;
5. loff_t pos;
6. size_t n;
7. void *p;
8. int err = 0;
10. mutex_lock(&m->lock);
12. /* Don't assume *ppos is where we left it */
13. if (unlikely(*ppos != m->read_pos)) {
14. m->read_pos = *ppos;
15. while ((err = traverse(m, *ppos)) == -EAGAIN) ---------------->1. 做什么？
16. ;
17. if (err) {
18. /* With prejudice... */
19. m->read_pos = 0;
20. m->version = 0;
21. m->index = 0;
22. m->count = 0;
23. goto Done;
24. }
25. }
27. /*
28. * seq_file->op->..m_start/m_stop/m_next may do special actions
29. * or optimisations based on the file->f_version, so we want to
30. * pass the file->f_version to those methods.
31. *
32. * seq_file->version is just copy of f_version, and seq_file
33. * methods can treat it simply as file version.
34. * It is copied in first and copied out after all operations.
35. * It is convenient to have it as part of structure to avoid the
36. * need of passing another argument to all the seq_file methods.
37. */
38. m->version = file->f_version;
39. /* grab buffer if we didn't have one */
40. if (!m->buf) {
41. m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
42. if (!m->buf)
43. goto Enomem;
44. }
45. /* if not empty - flush it first */
46. if (m->count) {
47. n = min(m->count, size);
48. err = copy_to_user(buf, m->buf + m->from, n);
49. if (err)
50. goto Efault;
51. m->count -= n;
52. m->from += n;
53. size -= n;
54. buf += n;
55. copied += n;
56. if (!m->count)
57. m->index++;
58. if (!size)
59. goto Done;
60. }
61. /* we need at least one record in buffer */
62. pos = m->index;
63. p = m->op->start(m, &pos);
64. while (1) {
65. err = PTR_ERR(p);
66. if (!p || IS_ERR(p))
67. break;
68. err = m->op->show(m, p); ------------->显示？
69. if (err < 0)
70. break;
71. if (unlikely(err))
72. m->count = 0;
73. if (unlikely(!m->count)) {
74. p = m->op->next(m, p, &pos);
75. m->index = pos;
76. continue;
77. }
78. if (m->count < m->size)
79. goto Fill;
80. m->op->stop(m, p);
81. kfree(m->buf);
82. m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
83. if (!m->buf)
84. goto Enomem;
85. m->count = 0;
86. m->version = 0;
87. pos = m->index;
88. p = m->op->start(m, &pos);
89. }
90. m->op->stop(m, p);
91. m->count = 0;
92. goto Done;
93. Fill:
94. /* they want more? let's try to get some more */
95. while (m->count < size) {
96. size_t offs = m->count;
97. loff_t next = pos;
98. p = m->op->next(m, p, &next);
99. if (!p || IS_ERR(p)) {
100. err = PTR_ERR(p);
101. break;
102. }
103. err = m->op->show(m, p);
104. if (m->count == m->size || err) {
105. m->count = offs;
106. if (likely(err <= 0))
107. break;
108. }
109. pos = next;
110. }
111. m->op->stop(m, p);
112. n = min(m->count, size);
113. err = copy_to_user(buf, m->buf, n);
114. if (err)
115. goto Efault;
116. copied += n;
117. m->count -= n;
118. if (m->count)
119. m->from = n;
120. else
121. pos++;
122. m->index = pos;
123. Done:
124. if (!copied)
125. copied = err;
126. else {
127. *ppos += copied;
128. m->read_pos += copied;
129. }
130. file->f_version = m->version;
131. mutex_unlock(&m->lock);
132. return copied;
133. Enomem:
134. err = -ENOMEM;
135. goto Done;
136. Efault:
137. err = -EFAULT;
138. goto Done;
139. }
140. EXPORT_SYMBOL(seq_read);
traverse 做了什么呢？
1. static int traverse(struct seq_file *m, loff_t offset)
2. {
3. loff_t pos = 0, index;
4. int error = 0;
5. void *p;
7. m->version = 0;
8. index = 0;
9. m->count = m->from = 0;
10. if (!offset) {
11. m->index = index;
12. return 0;
13. }
14. if (!m->buf) { ---------------->这个都不知道是不是空的？
15. m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
16. if (!m->buf)
17. return -ENOMEM;
18. }
19. p = m->op->start(m, &index);-----------调用m_start，是准备什么吗？
20. while (p) {
21. error = PTR_ERR(p);
22. if (IS_ERR(p))
23. break;
24. error = m->op->show(m, p);
25. if (error < 0)
26. break;
27. if (unlikely(error)) {
28. error = 0;
29. m->count = 0;
30. }
31. if (m->count == m->size)
32. goto Eoverflow;
33. if (pos + m->count > offset) {
34. m->from = offset - pos;
35. m->count -= m->from;
36. m->index = index;
37. break;
38. }
39. pos += m->count;
40. m->count = 0;
41. if (pos == offset) {
42. index++;
43. m->index = index;
44. break;
45. }
46. p = m->op->next(m, p, &index);
47. }
48. m->op->stop(m, p);
49. m->index = index;
50. return error;
52. Eoverflow:
53. m->op->stop(m, p);
54. kfree(m->buf);
55. m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
56. return !m->buf ? -ENOMEM : -EAGAIN;
57. }
m_start 做了什么？
1. static void *m_start(struct seq_file *m, loff_t *pos)
2. {
3. struct proc_maps_private *priv = m->private;
4. unsigned long last_addr = m->version;
5. struct mm_struct *mm;
6. struct vm_area_struct *vma, *tail_vma = NULL;
7. loff_t l = *pos;
9. /* Clear the per syscall fields in priv */
10. priv->task = NULL;
11. priv->tail_vma = NULL;
13. /*
14. * We remember last_addr rather than next_addr to hit with
15. * mmap_cache most of the time. We have zero last_addr at
16. * the beginning and also after lseek. We will have -1 last_addr
17. * after the end of the vmas.
18. */
20. if (last_addr == -1UL)
21. return NULL;
23. priv->task = get_pid_task(priv->pid, PIDTYPE_PID); ---------->通过pid 获取到task_struct
24. if (!priv->task)
25. return ERR_PTR(-ESRCH);
27. mm = mm_for_maps(priv->task);------------->这个看着很关键。。。，其实就是进行了权限检测，并得到了mm指针
28. if (!mm || IS_ERR(mm))
29. return mm;
30. down_read(&mm->mmap_sem);
32. tail_vma = get_gate_vma(priv->task->mm); ---------->获取vma的结束位置
33. priv->tail_vma = tail_vma;
35. /* Start with last addr hint */
36. vma = find_vma(mm, last_addr);-------------->从红黑树中得到对应的虚拟地址区域
37. if (last_addr && vma) {
38. vma = vma->vm_next;
39. goto out;
40. }
42. /*
43. * Check the vma index is within the range and do
44. * sequential scan until m_index.
45. */
46. vma = NULL;
47. if ((unsigned long)l < mm->map_count) {
48. vma = mm->mmap;
49. while (l-- && vma)
50. vma = vma->vm_next;
51. goto out;
52. }
54. if (l != mm->map_count)
55. tail_vma = NULL; /* After gate vma */
57. out:
58. if (vma)
59. return vma;
61. /* End of vmas has been reached */
62. m->version = (tail_vma != NULL)? 0: -1UL;
63. up_read(&mm->mmap_sem);
64. mmput(mm); -------------->释放对mm的使用记录
65. return tail_vma;
66. }
1. struct mm_struct *mm_for_maps(struct task_struct *task)
2. {
3. return mm_access(task, PTRACE_MODE_READ);------------>看着像是ptrace实现的额？
4. }
1. static struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
2. {
3. struct mm_struct *mm;
4. int err;
6. err = mutex_lock_killable(&task->signal->cred_guard_mutex);
7. if (err)
8. return ERR_PTR(err);
10. mm = get_task_mm(task); -------------->通过task_struct 获取mm_struct结构，并且增加对mm_struct 使用的计数
11. if (mm && mm != current->mm &&
12. !ptrace_may_access(task, mode) && --------------->对进程进行跟踪，这里会进行严格的权限检测
13. !capable(CAP_SYS_RESOURCE)) {
14. mmput(mm);
15. mm = ERR_PTR(-EACCES);
16. }
17. mutex_unlock(&task->signal->cred_guard_mutex);
19. return mm;
20. }
总结m_start 所做的事情，也就是说traverse找到了对应的vm_area_struct

pid-->task_struct->mm_struct->vm_area_struct

接下来就要调用show_map
1. static int show_map(struct seq_file *m, void *v)
2. {
3. struct vm_area_struct *vma = v;
4. struct proc_maps_private *priv = m->private;
5. struct task_struct *task = priv->task;
7. show_map_vma(m, vma);-------->显示vma 区域
9. if (m->count < m->size) /* vma is copied successfully */
10. m->version = (vma != get_gate_vma(task->mm))
11. ? vma->vm_start : 0;
12. return 0;
13. }
1. static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
2. {
3. struct mm_struct *mm = vma->vm_mm;
4. struct file *file = vma->vm_file;
5. vm_flags_t flags = vma->vm_flags;
6. unsigned long ino = 0;
7. unsigned long long pgoff = 0;
8. unsigned long start, end;
9. dev_t dev = 0;
10. int len;
12. if (file) {
13. struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
14. dev = inode->i_sb->s_dev;
15. ino = inode->i_ino;
16. pgoff = ((loff_t)vma->vm_pgoff) << PAGE_SHIFT;
17. }
19. /* We don't show the stack guard page in /proc/maps */
20. start = vma->vm_start;
21. if (stack_guard_page_start(vma, start)) -------->可以查看到该区域的增长是向下，还是向上的...
22. start += PAGE_SIZE;
23. end = vma->vm_end;
24. if (stack_guard_page_end(vma, end))
25. end -= PAGE_SIZE;
27. seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
28. start,
29. end,
30. flags & VM_READ ? 'r' : '-',
31. flags & VM_WRITE ? 'w' : '-',
32. flags & VM_EXEC ? 'x' : '-',
33. flags & VM_MAYSHARE ? 's' : 'p',
34. pgoff,
35. MAJOR(dev), MINOR(dev), ino, &len);------------>关键的一句输出
38. /*
39. * Print the dentry name for named mappings, and a
40. * special [heap] marker for the heap:
41. */
42. if (file) {
43. pad_len_spaces(m, len);
44. seq_path(m, &file->f_path, " ");
45. } else {
46. const char *name = arch_vma_name(vma);
47. if (!name) {
48. if (mm) {
49. if (vma->vm_start <= mm->brk &&
50. vma->vm_end >= mm->start_brk) { ------------>堆的区域
51. name = "[heap]";
52. } else if (vma->vm_start <= mm->start_stack &&
53. vma->vm_end >= mm->start_stack) {------------->栈的区域
54. name = "[stack]";
55. }
56. } else {
57. name = "[vdso]";
58. }
59. }
60. if (name) {
61. pad_len_spaces(m, len);
62. seq_puts(m, name);
63. }
64. }
65. seq_putc(m, ' ');
66. }
详细看一下mm_struct的几个成员：
1. unsigned long total_vm, locked_vm, shared_vm, exec_vm;
2. unsigned long stack_vm, reserved_vm, def_flags, nr_ptes;
3. unsigned long start_code, end_code, start_data, end_data;
4. unsigned long start_brk, brk, start_stack;
5. unsigned long arg_start, arg_end, env_start, env_end;
7. unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */
9. /*
10. * Special counters, in some configurations protected by the
11. * page_table_lock, in other configurations by being atomic.
12. */
13. struct mm_rss_stat rss_stat;
图片源自http://blog.csdn.net/dyllove98/article/details/8917197

参考：http://blog.csdn.net/dyllove98/article/details/8917197
【作者】张昺华

【出处】http://www.cnblogs.com/sky-heaven/

【博客园】 http://www.cnblogs.com/sky-heaven/

【知乎】 http://www.zhihu.com/people/zhang-bing-hua

【我的作品---旋转倒立摆】 http://v.youku.com/v_show/id_XODM5NDAzNjQw.html?spm=a2hzp.8253869.0.0&from=y1.7-2

【我的作品---自平衡自动循迹车】 http://v.youku.com/v_show/id_XODM5MzYyNTIw.html?spm=a2hzp.8253869.0.0&from=y1.7-2

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本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利.
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原文地址：https://www.cnblogs.com/sky-heaven/p/13686390.html

/proc/N/maps 信息是如何生成的？【转】

以进程1为例，查看proc长什么样子？

linux源码位置及主要宏

下面详细查看maps 相关的实现内容