Currently multiboot2 protocol loads image exactly at address specified in
ELF or multiboot2 header. This solution works quite well on legacy BIOS
platforms. It is possible because memory regions are placed at predictable
addresses (though I was not able to find any spec which says that it is
strong requirement, so, it looks that it is just a goodwill of hardware
designers). However, EFI platforms are more volatile. Even if required
memory regions live at specific addresses then they are sometimes simply
not free (e.g. used by boot/runtime services on Dell PowerEdge R820 and
OVMF). This means that you are not able to just set up final image
destination on build time. You have to provide method to relocate image
contents to real load address which is usually different than load address
specified in ELF and multiboot2 headers.
This patch provides all needed machinery to do self relocation in image code.
First of all GRUB2 reads min_addr (min. load addr), max_addr (max. load addr),
align (required image alignment), preference (it says which memory regions are
preferred by image, e.g. none, low, high) from multiboot_header_tag_relocatable
header tag contained in binary (at this stage load addresses from multiboot2
and/or ELF headers are ignored). Later loader tries to fulfill request (not only
that one) and if it succeeds then it informs image about real load address via
multiboot_tag_load_base_addr tag. At this stage GRUB2 role is finished. Starting
from now executable must cope with relocations itself using whole static and
dynamic knowledge provided by boot loader.
This patch does not provide functionality which could do relocations using
ELF relocation data. However, I was asked by Konrad Rzeszutek Wilk and Vladimir
'phcoder' Serbinenko to investigate that thing. It looks that relevant machinery
could be added to existing code (including this patch) without huge effort.
Additionally, ELF relocation could live in parallel with self relocation provided
by this patch. However, during research I realized that first of all we should
establish the details how ELF relocatable image should look like and how it should
be build. At least to build proper test/example files.
So, this patch just provides support for self relocatable images. If ELF file
with relocs is loaded then GRUB2 complains loudly and ignores it. Support for
such files will be added later.
This patch was tested with Xen image which uses that functionality. However, this Xen
feature is still under development and new patchset will be released in about 2-3 weeks.
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Vladimir Serbinenko <phcoder@gmail.com>
If image requested EFI boot services then skip multiboot2 memory maps.
Main reason for not providing maps is because they will likely be
invalid. We do a few allocations after filling them, e.g. for relocator
needs. Usually we do not care as we would have finished boot services.
If we keep boot services then it is easier/safer to not provide maps.
However, if image needs memory maps and they are not provided by bootloader
then it should get itself just before ExitBootServices() call.
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Vladimir Serbinenko <phcoder@gmail.com>
Add tags used to pass ImageHandle to loaded image if requested.
It is used by at least ExitBootServices() function.
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Vladimir Serbinenko <phcoder@gmail.com>
Add grub_relocator64_efi relocator. It will be used on EFI 64-bit platforms
when multiboot2 compatible image requests MULTIBOOT_TAG_TYPE_EFI_BS. Relocator
will set lower parts of %rax and %rbx accordingly to multiboot2 specification.
On the other hand processor mode, just before jumping into loaded image, will
be set accordingly to Unified Extensible Firmware Interface Specification,
Version 2.4 Errata B, section 2.3.4, x64 Platforms, boot services. This way
loaded image will be able to use EFI boot services without any issues.
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Vladimir Serbinenko <phcoder@gmail.com>
limit_time underflows when current time is less than 90000ms.
This causes packet fragments received during this time, i.e.,
till 90000ms pass since timer init, to be rejected.
Hence, set it to 0 if its less than 90000.
Signed-off-by: Sakar Arora <Sakar.Arora@nxp.com>
LLVM 3.9 now emits short form of jump instructions, but it is still using
32 bit addresses for some movl instructions. Fortunately it was caught early:
clang ... boot/i386/pc/boot.S
clang -cc1as: fatal error: error in backend: invalid .org offset '440' (at offset '441')
Add additional check to catch it during configure run and force -no-integrated-as.
Closes: 49200
More details in
https://lists.gnu.org/archive/html/grub-devel/2015-02/msg00099.htmlhttps://llvm.org/bugs/show_bug.cgi?id=22662
Writing the primary GPT before the backup may lead to a confusing
situation: booting a freshly updated system could consistently fail and
next boot will fall back to the old system if writing the primary works
but writing the backup fails. If the backup is written first and fails
the primary is left in the old state so the next boot will re-try and
possibly fail in the exact same way. Making that repeatable should make
it easier for users to identify the error.
Additionally if the firmware and OS disagree on the disk size, making
the backup inaccessible to GRUB, then just skip writing the backup.
When this happens the automatic call to `coreos-setgoodroot` after boot
will take care of repairing the backup.
The firmware and the OS may disagree on the disk configuration and size.
Although such a setup should be avoided users are unlikely to know about
the problem, assuming everything behaves like the OS. Tolerate this as
best we can and trust the reported on-disk location over the firmware
when looking for the backup GPT. If the location is inaccessible report
the error as best we can and move on.
I personally think this reads easier. Also has the side effect of
directly comparing the primary and backup tables instead of presuming
they are equal if the crc32 matches.
This ensures all code modifying GPT data include the same sanity check
that repair does. If revalidation fails the status flags are left in the
appropriate state.
The header was being relocated without checking the new location is
actually safe. If the BIOS thinks the disk is smaller than the OS then
repair may relocate the header into allocated space, failing the final
validation check. So only move it if the disk has grown.
Additionally, if the backup is valid then we can assume its current
location is good enough and leave it as-is.
Use the new status function which checks *_HEADER_VALID and
*_ENTRIES_VALID bits together. It doesn't make sense for the header and
entries bits to mismatch so don't allow for it.
Portions of the code attempted to handle the fact that GPT entries on
disk may be larger than the currently defined struct while others
assumed the data could be indexed by the struct size directly. This
never came up because no utility uses a size larger than 128 bytes but
for the sake of safety we need to do this by the spec.
GPT_BOTH_VALID is 4 bits so simple a boolean check is not sufficient.
This broken condition allowed gptprio to trust bogus disk locations in
headers that were marked invalid causing arbitrary disk corruption.
We may get more than one response before exiting out of loop in
grub_net_dns_lookup, but buffer was allocated for the first response only,
so storing answers from subsequent replies wrote past allocated size.
We never really use more than the very first address during lookup so there
is little point in collecting all of them. Just quit early if we already have
some reply.
Code needs serious redesign to actually collect multiple answers
and select the best fit according to requested type (IPv4 or IPv6).
Reported and tested by Michael Chang <mchang@suse.com>
