Detailed Stack Information Patch Next Generation

[Stefani Seibold <stefani@seibold.net>]

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);