linux-kernel - Re: [RFC patch 25/41] mm/kasan: Simplify stacktrace handling

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Date:   Wed, 10 Apr 2019 13:33:29 +0200
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux-MM <linux-mm@...ck.org>
Subject: Re: [RFC patch 25/41] mm/kasan: Simplify stacktrace handling

On Wed, Apr 10, 2019 at 1:06 PM Thomas Gleixner <tglx@...utronix.de> wrote:
>
> Replace the indirection through struct stack_trace by using the storage
> array based interfaces.
>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
> Cc: Alexander Potapenko <glider@...gle.com>
> Cc: Dmitry Vyukov <dvyukov@...gle.com>
> Cc: kasan-dev@...glegroups.com
> Cc: linux-mm@...ck.org
> ---
>  mm/kasan/common.c |   30 ++++++++++++------------------
>  mm/kasan/report.c |    7 ++++---
>  2 files changed, 16 insertions(+), 21 deletions(-)
>
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -48,34 +48,28 @@ static inline int in_irqentry_text(unsig
>                  ptr < (unsigned long)&__softirqentry_text_end);
>  }
>
> -static inline void filter_irq_stacks(struct stack_trace *trace)
> +static inline unsigned int filter_irq_stacks(unsigned long *entries,
> +                                            unsigned int nr_entries)
>  {
> -       int i;
> +       unsigned int i;
>
> -       if (!trace->nr_entries)
> -               return;
> -       for (i = 0; i < trace->nr_entries; i++)
> -               if (in_irqentry_text(trace->entries[i])) {
> +       for (i = 0; i < nr_entries; i++) {
> +               if (in_irqentry_text(entries[i])) {
>                         /* Include the irqentry function into the stack. */
> -                       trace->nr_entries = i + 1;
> -                       break;
> +                       return i + 1;
>                 }
> +       }
> +       return nr_entries;
>  }
>
>  static inline depot_stack_handle_t save_stack(gfp_t flags)
>  {
>         unsigned long entries[KASAN_STACK_DEPTH];
> -       struct stack_trace trace = {
> -               .nr_entries = 0,
> -               .entries = entries,
> -               .max_entries = KASAN_STACK_DEPTH,
> -               .skip = 0
> -       };
> +       unsigned int nent;
>
> -       save_stack_trace(&trace);
> -       filter_irq_stacks(&trace);
> -
> -       return depot_save_stack(&trace, flags);
> +       nent = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
> +       nent = filter_irq_stacks(entries, nent);
> +       return stack_depot_save(entries, nent, flags);
>  }
>
>  static inline void set_track(struct kasan_track *track, gfp_t flags)
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -100,10 +100,11 @@ static void print_track(struct kasan_tra
>  {
>         pr_err("%s by task %u:\n", prefix, track->pid);
>         if (track->stack) {
> -               struct stack_trace trace;
> +               unsigned long *entries;
> +               unsigned int nent;
>
> -               depot_fetch_stack(track->stack, &trace);
> -               print_stack_trace(&trace, 0);
> +               nent = stack_depot_fetch(track->stack, &entries);
> +               stack_trace_print(entries, nent, 0);
>         } else {
>                 pr_err("(stack is not available)\n");
>         }


Acked-by: Dmitry Vyukov <dvyukov@...gle.com>