[patch 3/4] c/r: procfs: add arg_start/end, env_start/end and exit_code members to /proc/$pid/stat

[Cyrill Gorcunov <gorcunov@openvz.org>]

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We would like to have an ability to restore command line
arguments and program environment pointers but first we
need to obtain them somehow. Thus we put these values into
/proc/$pid/stat. The exit_code is needed to restore zombie
tasks.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Vagin <avagin@openvz.org>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
---
 Documentation/filesystems/proc.txt |    5 +++++
 fs/proc/array.c                    |   20 +++++++++++++++++---
 2 files changed, 22 insertions(+), 3 deletions(-)

Index: linux-2.6.git/Documentation/filesystems/proc.txt
===================================================================
--- linux-2.6.git.orig/Documentation/filesystems/proc.txt
+++ linux-2.6.git/Documentation/filesystems/proc.txt
@@ -311,6 +311,11 @@ Table 1-4: Contents of the stat files (a
   start_data    address above which program data+bss is placed
   end_data      address below which program data+bss is placed
   start_brk     address above which program heap can be expanded with brk()
+  arg_start     address above which program command line is placed
+  arg_end       address below which program command line is placed
+  env_start     address above which program environment is placed
+  env_end       address below which program environment is placed
+  exit_code     the thread's exit_code in the form reported by the waitpid system call
 ..............................................................................
 
 The /proc/PID/maps file containing the currently mapped memory regions and
Index: linux-2.6.git/fs/proc/array.c
===================================================================
--- linux-2.6.git.orig/fs/proc/array.c
+++ linux-2.6.git/fs/proc/array.c
@@ -508,9 +508,23 @@ static int do_task_stat(struct seq_file
 	seq_put_decimal_ull(m, ' ', delayacct_blkio_ticks(task));
 	seq_put_decimal_ull(m, ' ', cputime_to_clock_t(gtime));
 	seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cgtime));
-	seq_put_decimal_ull(m, ' ', (mm && permitted) ? mm->start_data : 0);
-	seq_put_decimal_ull(m, ' ', (mm && permitted) ? mm->end_data : 0);
-	seq_put_decimal_ull(m, ' ', (mm && permitted) ? mm->start_brk : 0);
+
+	if (mm && permitted) {
+		seq_put_decimal_ull(m, ' ', mm->start_data);
+		seq_put_decimal_ull(m, ' ', mm->end_data);
+		seq_put_decimal_ull(m, ' ', mm->start_brk);
+		seq_put_decimal_ull(m, ' ', mm->arg_start);
+		seq_put_decimal_ull(m, ' ', mm->arg_end);
+		seq_put_decimal_ull(m, ' ', mm->env_start);
+		seq_put_decimal_ull(m, ' ', mm->env_end);
+	} else
+		seq_printf(m, " 0 0 0 0 0 0 0");
+
+	if (permitted)
+		seq_put_decimal_ll(m, ' ', task->exit_code);
+	else
+		seq_put_decimal_ll(m, ' ', 0);
+
 	seq_putc(m, '\n');
 	if (mm)
 		mmput(mm);