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    Subject[patch] procfs: provide stack information for threads
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    Hi everybody,

    This is the latest version of the formaly named "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 Andrew
    - slime done

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

    Greetings,
    Stefani

    fs/exec.c | 2 +
    fs/proc/array.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++-
    fs/proc/task_mmu.c | 14 +++++++++++++
    include/linux/sched.h | 1
    kernel/fork.c | 2 +
    5 files changed, 70 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 2009-06-04 09:29:47.000000000 +0200
    +++ linux-2.6.30/fs/exec.c 2009-06-04 09:32:35.000000000 +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 2009-06-04 09:29:47.000000000 +0200
    +++ linux-2.6.30/fs/proc/array.c 2009-06-04 10:37:53.000000000 +0200
    @@ -321,6 +321,55 @@
    p->nivcsw);
    }

    +static inline unsigned long get_stack_usage_in_bytes(struct vm_area_struct *vma,
    + struct task_struct *p)
    +{
    + unsigned long i;
    + struct page *page;
    + unsigned long stkpage;
    +
    + stkpage = KSTK_ESP(p) & PAGE_MASK;
    +
    +#ifdef CONFIG_STACK_GROWSUP
    + for (i = vma->vm_end; i-PAGE_SIZE > stkpage; i -= PAGE_SIZE) {
    +
    + page = follow_page(vma, i-PAGE_SIZE, 0);
    +
    + if (!IS_ERR(page) && page)
    + break;
    + }
    + return i - (p->stack_start & PAGE_MASK);
    +#else
    + for (i = vma->vm_start; i+PAGE_SIZE <= stkpage; i += PAGE_SIZE) {
    +
    + page = follow_page(vma, i, 0);
    +
    + if (!IS_ERR(page) && page)
    + break;
    + }
    + return (p->stack_start & PAGE_MASK) - i + PAGE_SIZE;
    +#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_usage_in_bytes(vma, p) >> 10);
    +
    + mmput(mm);
    + }
    +}
    +
    int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
    struct pid *pid, struct task_struct *task)
    {
    @@ -340,6 +389,7 @@
    task_show_regs(m, task);
    #endif
    task_context_switch_counts(m, task);
    + task_show_stack_usage(m, task);
    return 0;
    }

    @@ -481,7 +531,7 @@
    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 2009-06-04 09:29:47.000000000 +0200
    +++ linux-2.6.30/fs/proc/task_mmu.c 2009-06-04 09:32:35.000000000 +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 2009-06-04 09:29:47.000000000 +0200
    +++ linux-2.6.30/include/linux/sched.h 2009-06-04 09:32:35.000000000 +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 2009-06-04 09:29:47.000000000 +0200
    +++ linux-2.6.30/kernel/fork.c 2009-06-04 13:15:35.000000000 +0200
    @@ -1092,6 +1092,8 @@
    if (unlikely(current->ptrace))
    ptrace_fork(p, clone_flags);

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

    Signed-off-by: Stefani Seibold <stefani@seibold.net>



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