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Date: Thu, 25 Apr 2013 15:53:08 -0700
Message-ID: <CANN689EH-VyDefawtKdY=cVQNdZP1xN7cV4bDgXvYeniSCkvqA@mail.gmail.com>
Subject: Re: [GIT PULL] x86 fixes for 3.9
From: Michel Lespinasse <walken@google.com>
To: Matthew Garrett <matthew.garrett@nebula.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        "H. Peter Anvin" <hpa@linux.intel.com>, Borislav Petkov <bp@suse.de>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@elte.hu>,
        Josh Boyer <jwboyer@redhat.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Matt Fleming <matt.fleming@intel.com>, Paul Bolle <pebolle@tiscali.nl>,
        Thomas Gleixner <tglx@linutronix.de>
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On Thu, Apr 25, 2013 at 3:23 PM, Matthew Garrett
<matthew.garrett@nebula.com> wrote:
> On Thu, 2013-04-25 at 15:20 -0700, Linus Torvalds wrote:
>> On Thu, Apr 25, 2013 at 2:44 PM, H. Peter Anvin <hpa@linux.intel.com> wrote:
>> >
>> > -       if (!sys_table->runtime->query_variable_info)
>> > +       if (sys_table->runtime->hdr.revision < EFI_2_00_SYSTEM_TABLE_REVISION)
>> >                 return EFI_UNSUPPORTED;
>>
>> Is a EFI 2.00 system table *guaranteed* to have that
>> "query_variable_info" function? The above adds the version check, but
>> removes the check for a NULL pointer.
>
> As far as the spec's concerned, yes. As far as reality's concerned - if
> anything doesn't provide it, we're already crashing when
> efi_virt_query_variable_info() gets called. Nobody's complained so far.

Well, I don't know if this is related, but commit e971318bbed6 broke
the google EFI SMI driver with
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff814a7245>] variable_is_present+0x55/0x170
Call Trace:
[<ffffffff814a9936>] register_efivars+0x106/0x370
[<ffffffff818ff430>] ? firmware_map_add_early+0xb1/0xb1
[<ffffffff818ff6dd>] gsmi_init+0x2ad/0x3da
[<ffffffff8100020f>] do_one_initcall+0x3f/0x170
...

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.
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