From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
LKML <linux-kernel@vger.kernel.org>,
Kees Cook <keescook@chromium.org>,
Dave Hansen <dave.hansen@intel.com>,
Sean Christopherson <seanjc@google.com>
Subject: Re: [PATCH] x86/mm: Do not verify W^X at boot up
Date: Tue, 25 Oct 2022 19:47:50 +0200 [thread overview]
Message-ID: <Y1ghRheOJeAfJvdY@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAHk-=wjwjWAhPD=C7sW7804eOTSQRnpSrrQh44PFYpVjn8SjKg@mail.gmail.com>
On Tue, Oct 25, 2022 at 09:53:27AM -0700, Linus Torvalds wrote:
> On Tue, Oct 25, 2022 at 3:16 AM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > This seems to boot...
>
> This looks much better, thanks.
>
> But this:
>
> > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> > @@ -801,8 +803,9 @@ void __init poking_init(void)
> > spinlock_t *ptl;
> > pte_t *ptep;
> >
> > - poking_mm = copy_init_mm();
> > - BUG_ON(!poking_mm);
> > + __poking_mm = init_mm;
> > + mm_init(&__poking_mm, NULL, __poking_mm.user_ns);
> > + poking_mm = &__poking_mm;
>
> Should probably be just
>
> poking_mm = mm_alloc();
>
> because we shouldn't be messing with 'mm_init()' in places like this,
> and we shouldn't be exporting it either:
mm_alloc() uses allocate_mm() which requires a kmem_cache to be set-up.
Using the static storage and instead calling mm_init() on it avoids
that.
So I think we can have:
static struct mm_struct __poking_mm;
mm_init(&__poking_mm, NULL, init_mm.user_ns);
and leave out the assignment from init_mm.
next prev parent reply other threads:[~2022-10-25 17:48 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-24 15:45 [PATCH] x86/mm: Do not verify W^X at boot up Steven Rostedt
2022-10-24 16:14 ` Dave Hansen
2022-10-24 18:13 ` Steven Rostedt
2022-10-24 19:26 ` Steven Rostedt
2022-10-24 18:19 ` Linus Torvalds
2022-10-24 18:52 ` Steven Rostedt
2022-10-24 19:08 ` Linus Torvalds
2022-10-24 22:04 ` Steven Rostedt
2022-10-25 9:39 ` Peter Zijlstra
2022-10-25 10:16 ` Peter Zijlstra
2022-10-25 16:53 ` Linus Torvalds
2022-10-25 17:47 ` Peter Zijlstra [this message]
2022-10-25 18:14 ` Linus Torvalds
2022-10-25 18:46 ` Peter Zijlstra
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