The UEFI spec does not mention or reason about the configured size of
the virtual address space at all, but it does mention that all memory
should be identity mapped using a page size of 4 KiB.
This means that a LPA2 capable system that has any system memory outside
of the 48-bit addressable physical range and follows the spec to the
letter may serve page allocation requests from regions of memory that
the kernel cannot access unless it was built with LPA2 support and
enables it at runtime.
So let's ensure that all page allocations are limited to the 48-bit
range.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
The EFI spec is not very clear about which permissions are being given
when allocating pages of a certain type. However, it is quite obvious
that EFI_LOADER_CODE is more likely to permit execution than
EFI_LOADER_DATA, which becomes relevant once we permit booting the
kernel proper with the firmware's 1:1 mapping still active.
Ostensibly, recent systems such as the Surface Pro X grant executable
permissions to EFI_LOADER_CODE regions but not EFI_LOADER_DATA regions.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Expose the EFI boot time memory map to the kernel via a configuration
table. This is arch agnostic and enables future changes that remove the
dependency on DT on architectures that don't otherwise rely on it.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Currently, struct efi_boot_memmap is a struct that is passed around
between callers of efi_get_memory_map() and the users of the resulting
data, and which carries pointers to various variables whose values are
provided by the EFI GetMemoryMap() boot service.
This is overly complex, and it is much easier to carry these values in
the struct itself. So turn the struct into one that carries these data
items directly, including a flex array for the variable number of EFI
memory descriptors that the boot service may return.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
In allocate_e820(), call the EFI get_memory_map() service directly
instead of indirectly via efi_get_memory_map(). This avoids allocation
of a buffer and return of the full EFI memory map, which is not needed
here and would otherwise need to be freed.
Routine allocate_e820() only needs to know how many EFI memory
descriptors there are in the map to allocate an adequately sized
e820ext buffer, if it's needed. Note that since efi_get_memory_map()
returns a memory map buffer sized with extra headroom, allocate_e820()
now needs to explicitly factor that into the e820ext size calculation.
Signed-off-by: Lenny Szubowicz <lszubowi@redhat.com>
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Move efi_relocate_kernel() into a separate source file, so that it
only gets pulled into builds for architectures that use it. Since
efi_relocate_kernel() is the only user of efi_low_alloc(), let's
move that over as well.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Break out the code to create an aligned page allocation from mem.c
and move it into a function efi_allocate_pages_aligned() in alignedmem.c.
Update efi_allocate_pages() to invoke it unless the minimum alignment
equals the EFI page size (4 KB), in which case the ordinary page
allocator is sufficient. This way, efi_allocate_pages_aligned() will
only be pulled into the build if it is actually being used (which will
be on arm64 only in the immediate future)
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Update the description of of efi_relocate_kernel() to match Sphinx style.
Update parameter references in the description of other memory functions
to use @param style.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20200220065317.9096-1-xypron.glpk@gmx.de
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
The implementation of efi_high_alloc() uses a complicated way of
traversing the memory map to find an available region that is located
as close as possible to the provided upper limit, and calls AllocatePages
subsequently to create the allocation at that exact address.
This is precisely what the EFI_ALLOCATE_MAX_ADDRESS allocation type
argument to AllocatePages() does, and considering that EFI_ALLOC_ALIGN
only exceeds EFI_PAGE_SIZE on arm64, let's use AllocatePages() directly
and implement the alignment using code that the compiler can remove if
it does not exceed EFI_PAGE_SIZE.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Create a new source file mem.c to keep the routines involved in memory
allocation and deallocation and manipulation of the EFI memory map.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
