linux-kernel - Re: [RFC] perf: mmap2 not covering VM

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAGXu5jJ7igw995f_pm7C1qh15i3s4dxOjYqSB=JVZ+pJMtP5qw@mail.gmail.com>
Date:	Thu, 3 Oct 2013 08:34:16 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	David Ahern <dsahern@...il.com>, Jiri Olsa <jolsa@...hat.com>,
	Hugh Dickins <hughd@...gle.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC] perf: mmap2 not covering VM_CLONE regions

On Thu, Oct 3, 2013 at 2:13 AM, Stephane Eranian <eranian@...gle.com> wrote:
> On Thu, Oct 3, 2013 at 11:03 AM, Peter Zijlstra <peterz@...radead.org> wrote:
>> On Thu, Oct 03, 2013 at 10:55:28AM +0200, Stephane Eranian wrote:
>>> I don't know the MM code but I assume that that vm_mm struct is
>>> allocated dynamically
>>> and maybe you already grabbing a lock while doing this. Could we
>>> leverage that lock
>>> to increment a global generation number?
>>
>> Sure; something like so.. I just don't like global state nor adding to
>> mm_struct for just this.
>>
> I understand, I don't like global state either. I see you already
> have uprobes state in there. Thus to me, the perf situation is
> not much worse in terms of usefulness (frequency of use).
>
> Thanks.
>
>> ---
>>  include/linux/mm_types.h | 1 +
>>  kernel/fork.c            | 6 ++++++
>>  2 files changed, 7 insertions(+)
>>
>> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
>> index d9851eeb6e1d..3877b1e72a5b 100644
>> --- a/include/linux/mm_types.h
>> +++ b/include/linux/mm_types.h
>> @@ -436,6 +436,7 @@ struct mm_struct {
>>         int first_nid;
>>  #endif
>>         struct uprobes_state uprobes_state;
>> +       u64 mm_id;
>>  };
>>
>>  /* first nid will either be a valid NID or one of these values */
>> diff --git a/kernel/fork.c b/kernel/fork.c
>> index 086fe73ad6bd..b315f6227629 100644
>> --- a/kernel/fork.c
>> +++ b/kernel/fork.c
>> @@ -523,6 +523,8 @@ static void mm_init_aio(struct mm_struct *mm)
>>  #endif
>>  }
>>
>> +static u64 global_mm_id;
>> +
>>  static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
>>  {
>>         atomic_set(&mm->mm_users, 1);
>> @@ -537,6 +539,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
>>         spin_lock_init(&mm->page_table_lock);
>>         mm_init_aio(mm);
>>         mm_init_owner(mm, p);
>> +       mm->mm_id = 0;
>>
>>         if (likely(!mm_alloc_pgd(mm))) {
>>                 mm->def_flags = 0;
>> @@ -1422,6 +1425,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
>>          */
>>         write_lock_irq(&tasklist_lock);
>>
>> +       if (p->mm && !p->mm->mm_id)
>> +               p->mm->mm_id = ++global_mm_id;
>> +
>>         /* CLONE_PARENT re-uses the old parent */
>>         if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
>>                 p->real_parent = current->real_parent;

FWIW, I like this approach.

-Kees

-- 
Kees Cook
Chrome OS Security
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/