These fields must reflect the ROM-BIOS's geometry for CHS-based
loaders to correctly load their next stage. Most loaders do not
query the ROM-BIOS (Int13.08), relying on the BPB fields to hold
the correct values already.
Tested with lDebug booted in qemu via grub2's
FreeDOS direct loading support, refer to
https://bitbucket.org/ecm/ldosboot + https://bitbucket.org/ecm/ldebug
(For this test, lDebug's iniload.asm must be assembled with
-D_QUERY_GEOMETRY=0 to leave the BPB values provided by grub.)
Signed-off-by: C. Masloch <pushbx@38.de>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Rename GRUB_LINUX_MAGIC_SIGNATURE GRUB_LINUX_I386_MAGIC_SIGNATURE,
to be usable in code that supports more than one image type.
Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The definition of bpb's num_total_sectors_16 and num_total_sectors_32
is that either the 16-bit field is non-zero and is used (in which case
eg mkfs.fat sets the 32-bit field to zero), or it is zero and the
32-bit field is used. Therefore, a BPB is invalid only if *both*
fields are zero; having one field as zero and the other as non-zero is
the case to be expected. (Indeed, according to Microsoft's specification
one of the fields *must* be zero, and the other non-zero.)
This affects all users of grub_chainloader_patch_bpb which are in
chainloader.c, freedos.c, and ntldr.c
Some descriptions of the semantics of these two fields:
https://www.win.tue.nl/~aeb/linux/fs/fat/fat-1.html
The old 2-byte fields "total number of sectors" and "number of
sectors per FAT" are now zero; this information is now found in
the new 4-byte fields.
(Here given in the FAT32 EBPB section but the total sectors 16/32 bit
fields semantic is true of FAT12 and FAT16 too.)
https://wiki.osdev.org/FAT#BPB_.28BIOS_Parameter_Block.29
19 | 2 | The total sectors in the logical volume. If this value is 0,
it means there are more than 65535 sectors in the volume, and the actual
count is stored in "Large Sectors (bytes 32-35).
32 | 4 | Large amount of sector on media. This field is set if there
are more than 65535 sectors in the volume.
(Doesn't specify what the "large" field is set to when unused, but as
mentioned mkfs.fat sets it to zero then.)
https://technet.microsoft.com/en-us/library/cc976796.aspx
0x13 | WORD | 0x0000 |
Small Sectors . The number of sectors on the volume represented in 16
bits (< 65,536). For volumes larger than 65,536 sectors, this field
has a value of zero and the Large Sectors field is used instead.
0x20 | DWORD | 0x01F03E00 |
Large Sectors . If the value of the Small Sectors field is zero, this
field contains the total number of sectors in the FAT16 volume. If the
value of the Small Sectors field is not zero, the value of this field
is zero.
https://staff.washington.edu/dittrich/misc/fatgen103.pdf page 10
BPB_TotSec16 | 19 | 2 |
This field is the old 16-bit total count of sectors on the volume.
This count includes the count of all sectors in all four regions of the
volume. This field can be 0; if it is 0, then BPB_TotSec32 must be
non-zero. For FAT32 volumes, this field must be 0. For FAT12 and
FAT16 volumes, this field contains the sector count, and
BPB_TotSec32 is 0 if the total sector count “fits” (is less than
0x10000).
BPB_TotSec32 | 32 | 4 |
This field is the new 32-bit total count of sectors on the volume.
This count includes the count of all sectors in all four regions of the
volume. This field can be 0; if it is 0, then BPB_TotSec16 must be
non-zero. For FAT32 volumes, this field must be non-zero. For
FAT12/FAT16 volumes, this field contains the sector count if
BPB_TotSec16 is 0 (count is greater than or equal to 0x10000).
(This specifies that an unused BPB_TotSec32 field is set to zero.)
By the way fix offsets in include/grub/fat.h.
Tested with lDebug booted in qemu via grub2's
FreeDOS direct loading support, refer to
https://bitbucket.org/ecm/ldosboot + https://bitbucket.org/ecm/ldebug
Signed-off-by: C. Masloch <pushbx@38.de>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Previously we had multiboot and multiboot2 declaring the same symbols.
This can potentially lead to aliasing and strange behaviours when e.g.
module instead of module2 is used with multiboot2.
Bug: #51137
In util/getroot and efidisk slightly modify exitsing comment to mostly
retain it but still make GCC7 compliant with respect to fall through
annotation.
In grub-core/lib/xzembed/xz_dec_lzma2.c it adds same comments as
upstream.
In grub-core/tests/setjmp_tets.c declare functions as "noreturn" to
suppress GCC7 warning.
In grub-core/gnulib/regexec.c use new __attribute__, because existing
annotation is not recognized by GCC7 parser (which requires that comment
immediately precedes case statement).
Otherwise add FALLTHROUGH comment.
Closes: 50598
In case of GRUB we put remapper after domain pages and not at 0x0.
In this case we use max_addr to put remapper. Unfortunately we increment
max_addr as well in this case resulting in virt mapping mapping page
at old max_addr and trying to boot using new max_addr.
Closes 46014.
Modern pvops linux kernels support a p2m list not covered by the
kernel mapping. This capability is flagged by an elf-note specifying
the virtual address the kernel is expecting the p2m list to be mapped
to.
In case the elf-note is set by the kernel don't place the p2m list
into the kernel mapping, but map it to the given address. This will
allow to support domains with larger memory, as the kernel mapping is
limited to 2GB and a domain with huge memory in the TB range will have
a p2m list larger than this.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Modify the page table construction to allow multiple virtual regions
to be mapped. This is done as preparation for removing the p2m list
from the initial kernel mapping in order to support huge pv domains.
This allows a cleaner approach for mapping the relocator page by
using this capability.
The interface to the assembler level of the relocator has to be changed
in order to be able to process multiple page table areas.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Modern pvops linux kernels support an initrd not covered by the initial
mapping. This capability is flagged by an elf-note.
In case the elf-note is set by the kernel don't place the initrd into
the initial mapping. This will allow to load larger initrds and/or
support domains with larger memory, as the initial mapping is limited
to 2GB and it is containing the p2m list.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Do the allocation of page tables in a separate function. This will
allow to do the allocation at different times of the boot preparations
depending on the features the kernel is supporting.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Do the allocation of special pages (start info, console and xenbus
ring buffers) in a separate function. This will allow to do the
allocation at different times of the boot preparations depending on
the features the kernel is supporting.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Do the p2m list allocation of the to be loaded kernel in a separate
function. This will allow doing the p2m list allocation at different
times of the boot preparations depending on the features the kernel
is supporting.
While at this remove superfluous setting of first_p2m_pfn and
nr_p2m_frames as those are needed only in case of the p2m list not
being mapped by the initial kernel mapping.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Various features and parameters of a pv-kernel are specified via
elf notes in the kernel image. Those notes are part of the interface
between the Xen hypervisor and the kernel.
Instead of using num,bers in the code when interpreting the elf notes
make use of the header supplied by Xen for that purpose.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The loader for xen paravirtualized environment is using lots of global
variables. Reduce the number by making them either local or by putting
them into a single state structure.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
When loading a Xen pv-kernel avoid memory leaks in case of errors.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The loader for xen paravirtualized environment isn't callable multiple
times as it won't free any memory in case of failure.
Call grub_relocator_unload() as other modules do it before allocating
a new relocator or when unloading the module.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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>
struct ... foo = { 0, } is valid initializer, but older GCC emits
warning which is fatal error due to -Werror=missing-field-initializer.
So simply use full initializer to avoid these errors. This was fixed
probably in GCC 4.7.
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=36750
Currently, if "linux" fails, the "goto fail;" in grub_cmd_initrd sends us
into grub_initrd_close() without grub_initrd_init() being called, and thus
it never clears initrd_ctx->components. grub_initrd_close() then frees that
address, which is stale data from the stack. If the stack happens to have a
stale *address* there that matches a recent allocation, then you'll get a
double free later.
So initialize the memory up front.
Signed-off-by: Peter Jones <pjones@redhat.com>
