Detailed Stack Information Patch Next Generation

Stefani Seibold
2009-06-03T21:12:24Z

Hi everybody,

kernel 2.6.30 is near so i think it is time for the next try.

This is the new version of the "detailed stack info" patch which give
you 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 start address of the stack.

Also there is a new entry "stack usage" in /proc/<pid>/{task/*,}/status
which will you give the current stack usage in 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.

Changes since last posting:

- Redesigned everything what was suggested by Ingo
- the thread watch monitor is gone
- the /proc/stackmon entry is also gone
- slime done

The patch is against 2.6.30-rc7 and tested with on intel and ppc
architectures.

I think it is now ready for inclusion in the main kernel. Ingo what do
you think?

Greetings,
Stefani

fs/exec.c | 2 +
fs/proc/array.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++-
fs/proc/task_mmu.c | 14 ++++++++++
include/linux/sched.h | 1
kernel/fork.c | 3 ++
5 files changed, 88 insertions(+), 1 deletion(-)

-patch begins here--------------------------------------------------------------

diff -u -N -r linux-2.6.30.orig/fs/exec.c linux-2.6.30/fs/exec.c
--- linux-2.6.30.orig/fs/exec.c 2009-06-03 17:36:41.000000000 +0200
+++ linux-2.6.30/fs/exec.c 2009-06-03 17:30:47.000000000 +0200
@@ -1328,6 +1328,8 @@
if (retval < 0)
goto out;

+ current->stack_start = current->mm->start_stack;
+
/* execve succeeded */
current->fs->in_exec = 0;
current->in_execve = 0;
diff -u -N -r linux-2.6.30.orig/fs/proc/array.c linux-2.6.30/fs/proc/array.c
--- linux-2.6.30.orig/fs/proc/array.c 2009-06-03 17:36:41.000000000 +0200
+++ linux-2.6.30/fs/proc/array.c 2009-06-03 17:32:53.000000000 +0200
@@ -82,6 +82,7 @@
#include <linux/pid_namespace.h>
#include <linux/ptrace.h>
#include <linux/tracehook.h>
+#include <linux/pfn.h>

#include <asm/pgtable.h>
#include <asm/processor.h>
@@ -321,6 +322,71 @@
p->nivcsw);
}

+#ifdef CONFIG_STACK_GROWSUP
+static inline unsigned long get_stack_pages(struct vm_area_struct *vma,
+ struct task_struct *p)
+{
+ unsigned long i;
+ struct page *page;
+ unsigned long stack_usage;
+ unsigned long esp;
+
+ esp = KSTK_ESP(p);
+
+ stack_usage = (PFN_ALIGN(esp)-PFN_ALIGN(p->stack_start));
+
+ for (i = vma->vm_end; i-PAGE_SIZE > esp; i -= PAGE_SIZE) {
+
+ page = follow_page(vma, i-PAGE_SIZE, 0);
+
+ if ((!IS_ERR(page) == 0) || (page))
+ break;
+ }
+ return ((i - esp + stack_usage) >> (PAGE_SHIFT)) + 1;
+}
+#else
+static inline unsigned long get_stack_pages(struct vm_area_struct *vma,
+ struct task_struct *p)
+{
+ unsigned long i;
+ struct page *page;
+ unsigned long stack_usage;
+ unsigned long esp;
+
+ esp = KSTK_ESP(p);
+
+ stack_usage = (PFN_ALIGN(p->stack_start) - PFN_ALIGN(esp));
+
+ for (i = vma->vm_start; i+PAGE_SIZE <= esp; i += PAGE_SIZE) {
+
+ page = follow_page(vma, i, 0);
+
+ if ((!IS_ERR(page) == 0) || (page))
+ break;
+ }
+ return ((esp - i + stack_usage) >> (PAGE_SHIFT)) + 1;
+}
+#endif
+
+static inline void task_show_stack_usage(struct seq_file *m,
+ struct task_struct *p)
+{
+ struct vm_area_struct *vma;
+ struct mm_struct *mm;
+
+ mm = get_task_mm(p);
+
+ if (mm) {
+ vma = find_vma(mm, p->stack_start);
+
+ if (vma)
+ seq_printf(m, "Stack usage:\t%lu kB\n",
+ get_stack_pages(vma, p) << (PAGE_SHIFT - 10));
+
+ mmput(mm);
+ }
+}
+
int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
{
@@ -340,6 +406,7 @@
task_show_regs(m, task);
#endif
task_context_switch_counts(m, task);
+ task_show_stack_usage(m, task);
return 0;
}

@@ -481,7 +548,7 @@
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 -u -N -r linux-2.6.30.orig/fs/proc/task_mmu.c linux-2.6.30/fs/proc/task_mmu.c
--- linux-2.6.30.orig/fs/proc/task_mmu.c 2009-06-03 17:36:41.000000000 +0200
+++ linux-2.6.30/fs/proc/task_mmu.c 2009-06-03 17:30:47.000000000 +0200
@@ -242,6 +242,20 @@
} else if (vma->vm_start <= mm->start_stack &&
vma->vm_end >= mm->start_stack) {
name = "[stack]";
+ } else {
+ unsigned long stack_start;
+
+ stack_start =
+ ((struct proc_maps_private *)
+ m->private)->task->stack_start;
+
+ if (vma->vm_start <= stack_start &&
+ vma->vm_end >= stack_start) {
+ pad_len_spaces(m, len);
+ seq_printf(m,
+ "[thread stack: %08lx]",
+ stack_start);
+ }
}
} else {
name = "[vdso]";
diff -u -N -r linux-2.6.30.orig/include/linux/sched.h linux-2.6.30/include/linux/sched.h
--- linux-2.6.30.orig/include/linux/sched.h 2009-06-03 17:36:41.000000000 +0200
+++ linux-2.6.30/include/linux/sched.h 2009-06-03 17:30:47.000000000 +0200
@@ -1429,6 +1429,7 @@
/* state flags for use by tracers */
unsigned long trace;
#endif
+ unsigned long stack_start;
};

/* Future-safe accessor for struct task_struct's cpus_allowed. */
diff -u -N -r linux-2.6.30.orig/kernel/fork.c linux-2.6.30/kernel/fork.c
--- linux-2.6.30.orig/kernel/fork.c 2009-06-03 17:36:42.000000000 +0200
+++ linux-2.6.30/kernel/fork.c 2009-06-03 17:30:47.000000000 +0200
@@ -1092,6 +1092,9 @@
if (unlikely(current->ptrace))
ptrace_fork(p, clone_flags);

+ p->stack_start = (stack_start == KSTK_ESP(current)) ?
+ current->stack_start : stack_start;
+
/* Perform scheduler related setup. Assign this task to a CPU. */
sched_fork(p, clone_flags);