From: Ard Biesheuvel <ardb@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Jörg Otte" <jrg.otte@gmail.com>,
linux-efi <linux-efi@vger.kernel.org>,
"Arvind Sankar" <nivedita@alum.mit.edu>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: Kernel V5.7-rc1 doesn't boot (EFI?)
Date: Tue, 14 Apr 2020 20:32:32 +0200 [thread overview]
Message-ID: <CAMj1kXE9046X9EDd636Bw1A9npv0QKAuLcTAzMXAn=JVZeCN0Q@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wi-s0mmLAVg-aSmNU55=cE8ES7mC=Mc3Wn62P8W9VjY-A@mail.gmail.com>
On Tue, 14 Apr 2020 at 20:27, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Tue, Apr 14, 2020 at 3:50 AM Ard Biesheuvel <ardb@kernel.org> wrote:
> >
> > [*] GRUB on x86 turns out not to zero initialize BSS when it invokes
> > the EFI stub as a PE/COFF executable
>
> The fix seems to be to put all globals in the .data section, even if
> they don't have initializers.
>
> That seems very fragile. Very easy to forget to not declare some
> static variable with __efistub_global.
>
> Could we not make the EFI stub code zero out the BSS itself? Perhaps
> setting a warning flag (for a later printout) if it wasn't already
> zero, so that people could point fingers are buggy loaders..
>
That is the quick fix, but Arvind is working on getting rid of
__efistub_global entirely, and use the right linker foo to put .bss in
.data. This gives a tiny bit of bloat, but we are talking about a
handful of bools here.
next prev parent reply other threads:[~2020-04-14 18:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-14 10:40 Kernel V5.7-rc1 doesn't boot (EFI?) Jörg Otte
2020-04-14 10:50 ` Ard Biesheuvel
2020-04-14 16:32 ` Jörg Otte
2020-04-14 16:35 ` Ard Biesheuvel
2020-04-15 7:45 ` Ingo Molnar
2020-04-15 8:35 ` Jörg Otte
2020-04-15 9:58 ` Ard Biesheuvel
2020-04-14 18:27 ` Linus Torvalds
2020-04-14 18:32 ` Ard Biesheuvel [this message]
2020-04-14 18:44 ` Linus Torvalds
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