procfs: provide stack information for threads
A patch to give a better overview of the userland application stack usage,
especially for embedded linux.
Currently you are only able to dump the main process/thread stack usage
which is showed in /proc/pid/status by the "VmStk" Value. But you get no
information about the consumed stack memory of the the threads.
There is an enhancement in the /proc/<pid>/{task/*,}/*maps and which marks
the vm mapping where the thread stack pointer reside with "[thread stack
xxxxxxxx]". xxxxxxxx is the maximum size of stack. This is a value
information, because libpthread doesn't set the start of the stack to the
top of the mapped area, depending of the pthread usage.
A sample output of /proc/<pid>/task/<tid>/maps looks like:
08048000-08049000 r-xp 00000000 03:00 8312 /opt/z
08049000-0804a000 rw-p 00001000 03:00 8312 /opt/z
0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
a7d12000-a7d13000 ---p 00000000 00:00 0
a7d13000-a7f13000 rw-p 00000000 00:00 0 [thread stack: 001ff4b4]
a7f13000-a7f14000 ---p 00000000 00:00 0
a7f14000-a7f36000 rw-p 00000000 00:00 0
a7f36000-a8069000 r-xp 00000000 03:00 4222 /lib/libc.so.6
a8069000-a806b000 r--p 00133000 03:00 4222 /lib/libc.so.6
a806b000-a806c000 rw-p 00135000 03:00 4222 /lib/libc.so.6
a806c000-a806f000 rw-p 00000000 00:00 0
a806f000-a8083000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
a8083000-a8084000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
a8084000-a8085000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
a8085000-a8088000 rw-p 00000000 00:00 0
a8088000-a80a4000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
a80a4000-a80a5000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
a80a5000-a80a6000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
afaf5000-afb0a000 rw-p 00000000 00:00 0 [stack]
ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
Also there is a new entry "stack usage" in /proc/<pid>/{task/*,}/status
which will you give the current stack usage in kb.
A sample output of /proc/self/status looks like:
Name: cat
State: R (running)
Tgid: 507
Pid: 507
.
.
.
CapBnd: fffffffffffffeff
voluntary_ctxt_switches: 0
nonvoluntary_ctxt_switches: 0
Stack usage: 12 kB
I also fixed stack base address in /proc/<pid>/{task/*,}/stat to the base
address of the associated thread stack and not the one of the main
process. This makes more sense.
[akpm@linux-foundation.org: fs/proc/array.c now needs walk_page_range()]
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/exec.c b/fs/exec.c
index 69bb9d8..5c833c1 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1357,6 +1357,8 @@
if (retval < 0)
goto out;
+ current->stack_start = current->mm->start_stack;
+
/* execve succeeded */
current->fs->in_exec = 0;
current->in_execve = 0;
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 725a650..0c6bc60 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -82,6 +82,7 @@
#include <linux/pid_namespace.h>
#include <linux/ptrace.h>
#include <linux/tracehook.h>
+#include <linux/swapops.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
@@ -321,6 +322,87 @@
p->nivcsw);
}
+struct stack_stats {
+ struct vm_area_struct *vma;
+ unsigned long startpage;
+ unsigned long usage;
+};
+
+static int stack_usage_pte_range(pmd_t *pmd, unsigned long addr,
+ unsigned long end, struct mm_walk *walk)
+{
+ struct stack_stats *ss = walk->private;
+ struct vm_area_struct *vma = ss->vma;
+ pte_t *pte, ptent;
+ spinlock_t *ptl;
+ int ret = 0;
+
+ pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+ for (; addr != end; pte++, addr += PAGE_SIZE) {
+ ptent = *pte;
+
+#ifdef CONFIG_STACK_GROWSUP
+ if (pte_present(ptent) || is_swap_pte(ptent))
+ ss->usage = addr - ss->startpage + PAGE_SIZE;
+#else
+ if (pte_present(ptent) || is_swap_pte(ptent)) {
+ ss->usage = ss->startpage - addr + PAGE_SIZE;
+ pte++;
+ ret = 1;
+ break;
+ }
+#endif
+ }
+ pte_unmap_unlock(pte - 1, ptl);
+ cond_resched();
+ return ret;
+}
+
+static inline unsigned long get_stack_usage_in_bytes(struct vm_area_struct *vma,
+ struct task_struct *task)
+{
+ struct stack_stats ss;
+ struct mm_walk stack_walk = {
+ .pmd_entry = stack_usage_pte_range,
+ .mm = vma->vm_mm,
+ .private = &ss,
+ };
+
+ if (!vma->vm_mm || is_vm_hugetlb_page(vma))
+ return 0;
+
+ ss.vma = vma;
+ ss.startpage = task->stack_start & PAGE_MASK;
+ ss.usage = 0;
+
+#ifdef CONFIG_STACK_GROWSUP
+ walk_page_range(KSTK_ESP(task) & PAGE_MASK, vma->vm_end,
+ &stack_walk);
+#else
+ walk_page_range(vma->vm_start, (KSTK_ESP(task) & PAGE_MASK) + PAGE_SIZE,
+ &stack_walk);
+#endif
+ return ss.usage;
+}
+
+static inline void task_show_stack_usage(struct seq_file *m,
+ struct task_struct *task)
+{
+ struct vm_area_struct *vma;
+ struct mm_struct *mm = get_task_mm(task);
+
+ if (mm) {
+ down_read(&mm->mmap_sem);
+ vma = find_vma(mm, task->stack_start);
+ if (vma)
+ seq_printf(m, "Stack usage:\t%lu kB\n",
+ get_stack_usage_in_bytes(vma, task) >> 10);
+
+ up_read(&mm->mmap_sem);
+ mmput(mm);
+ }
+}
+
int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
{
@@ -340,6 +422,7 @@
task_show_regs(m, task);
#endif
task_context_switch_counts(m, task);
+ task_show_stack_usage(m, task);
return 0;
}
@@ -481,7 +564,7 @@
rsslim,
mm ? mm->start_code : 0,
mm ? mm->end_code : 0,
- (permitted && mm) ? mm->start_stack : 0,
+ (permitted) ? task->stack_start : 0,
esp,
eip,
/* The signal information here is obsolete.
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 366b101..2a1bef9 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -243,6 +243,25 @@
} else if (vma->vm_start <= mm->start_stack &&
vma->vm_end >= mm->start_stack) {
name = "[stack]";
+ } else {
+ unsigned long stack_start;
+ struct proc_maps_private *pmp;
+
+ pmp = m->private;
+ stack_start = pmp->task->stack_start;
+
+ if (vma->vm_start <= stack_start &&
+ vma->vm_end >= stack_start) {
+ pad_len_spaces(m, len);
+ seq_printf(m,
+ "[threadstack:%08lx]",
+#ifdef CONFIG_STACK_GROWSUP
+ vma->vm_end - stack_start
+#else
+ stack_start - vma->vm_start
+#endif
+ );
+ }
}
} else {
name = "[vdso]";