[patch 2/3] [PATCH] fs, proc: Add start_data, end_data, start_brk members to /proc/$pid/stat v4

Cyrill Gorcunov
2011-12-12T20:17:23Z

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The mm->start_code/end_code, mm->start_data/end_data,
mm->start_brk are involved into calculation of program
text/data segment sizes (which might be seen in
/proc/<pid>/statm) and into brk() call final address.

In a sake of restore we need to know all these values.
While mm->start_code/end_code already present in
/proc/$pid/stat, the rest members are not, so this
patch brings them in.

The restore procedure of these members is addressed
in another patch and uses prctl facility.

v2:
- Kees and Alexey pointed out that "1" hack is unnecessary,
so make it to have plain (mm && permitted) ? mm->member : 0
form.

v3:
- Andrew pointed that documentation update is missed.
Chagelog is updated as well.

v4:
- Update proc.txt to address concerns from Kees and Kame.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Alexey Dobriyan <adobriyan@gmail.com>
---
Documentation/filesystems/proc.txt | 3 +++
fs/proc/array.c | 7 +++++--
2 files changed, 8 insertions(+), 2 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
@@ -305,6 +305,9 @@ Table 1-4: Contents of the stat files (a
blkio_ticks time spent waiting for block IO
gtime guest time of the task in jiffies
cgtime guest time of the task children in jiffies
+ 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 expaned with brk() 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
@@ -464,7 +464,7 @@ static int do_task_stat(struct seq_file

seq_printf(m, "%d (%s) %c %d %d %d %d %d %u %lu \
%lu %lu %lu %lu %lu %ld %ld %ld %ld %d 0 %llu %lu %ld %lu %lu %lu %lu %lu \
-%lu %lu %lu %lu %lu %lu %lu %lu %d %d %u %u %llu %lu %ld\n",
+%lu %lu %lu %lu %lu %lu %lu %lu %d %d %u %u %llu %lu %ld %lu %lu %lu\n",
pid_nr_ns(pid, ns),
tcomm,
state,
@@ -511,7 +511,10 @@ static int do_task_stat(struct seq_file
task->policy,
(unsigned long long)delayacct_blkio_ticks(task),
cputime_to_clock_t(gtime),
- cputime_to_clock_t(cgtime));
+ cputime_to_clock_t(cgtime),
+ (mm && permitted) ? mm->start_data : 0,
+ (mm && permitted) ? mm->end_data : 0,
+ (mm && permitted) ? mm->start_brk : 0);
if (mm)
mmput(mm);
return 0;