From: "Jan Beulich" <JBeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH 1/3] x86/EFI: don't apply relocations to l{2, 3}_bootmap
Date: Fri, 19 Aug 2016 06:05:50 -0600 [thread overview]
Message-ID: <57B7123E0200007800107622@prv-mh.provo.novell.com> (raw)
In-Reply-To: <8713cae2-512a-cca3-b9ef-43e863fe5b89@citrix.com>
>>> On 19.08.16 at 12:34, <andrew.cooper3@citrix.com> wrote:
> On 19/08/16 08:50, Jan Beulich wrote:
>> Other than claimed in commit 2ce5963727's ("x86: construct the
>> {l2,l3}_bootmap at compile time") the initialization of the two page
>> tables doesn't take care of everything without furher adjustment: The
>> compile time initialization obviously requires base relocations, and
>> those get processed after efi_arch_memory_setup(). Hence without
>> additional care the correctly initialized values may then get wrongly
>> "adjusted" again. Except the two table from being subject to base
>> relocation.
>
> Do you mean Exempt? "Except the two tables" doesn't parse.
Hmm, my dictionary tells me that "except" can be used as a verb,
and it also tells me that I rather don't mean "exempt".
>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>>
>> --- a/xen/arch/x86/efi/efi-boot.h
>> +++ b/xen/arch/x86/efi/efi-boot.h
>> @@ -47,11 +47,23 @@ static void __init efi_arch_relocate_ima
>>
>> for ( base_relocs = __base_relocs_start; base_relocs < __base_relocs_end; )
>> {
>> - unsigned int i, n;
>> + unsigned int i = 0, n;
>>
>> n = (base_relocs->size - sizeof(*base_relocs)) /
>> sizeof(*base_relocs->entries);
>> - for ( i = 0; i < n; ++i )
>> +
>> + /*
>> + * Relevant l{2,3}_bootmap entries get initialized explicitly in
>> + * efi_arch_memory_setup(), so we must not apply relocations there.
>> + * l2_identmap's first slot, otoh, should be handled normally, as
>
> And l3 surely?
Generally yes, but the comment refers to efi_arch_memory_setup(),
which only touches l2_identmap[]. I.e. I'm trying to answer the
reasonably to raise question why it doesn't need special casing here
despite that function touching it.
Jan
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next prev parent reply other threads:[~2016-08-19 12:05 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-19 7:39 [PATCH 0/3] x86/EFI: boot adjustments Jan Beulich
2016-08-19 7:50 ` [PATCH 1/3] x86/EFI: don't apply relocations to l{2, 3}_bootmap Jan Beulich
2016-08-19 10:34 ` Andrew Cooper
2016-08-19 12:05 ` Jan Beulich [this message]
2016-08-19 7:51 ` [PATCH 2/3] x86/EFI: be cautious about being handed control with CR4.PGE enabled Jan Beulich
2016-08-19 12:26 ` Andrew Cooper
2016-08-19 7:52 ` [PATCH 3/3] x86/EFI: don't accept 64-bit base relocations on page tables Jan Beulich
2016-08-19 12:39 ` Andrew Cooper
2016-08-19 12:57 ` Jan Beulich
2016-08-30 16:35 ` Andrew Cooper
2016-08-31 12:28 ` Jan Beulich
2016-08-31 12:32 ` Andrew Cooper
2016-08-31 13:03 ` Jan Beulich
2016-08-30 16:18 ` Ping: " Jan Beulich
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