efi/libstub/x86: Avoid EFI map buffer alloc in allocate_e820()

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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>

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Lenny Szubowicz 2020-05-07 14:33:32 -04:00 • committed by Ard Biesheuvel

parent 8f592ada59

commit fd62619598

3 changed files with 22 additions and 17 deletions

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13

drivers/firmware/efi/libstub/efistub.h

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2

drivers/firmware/efi/libstub/mem.c

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24

drivers/firmware/efi/libstub/x86-stub.c

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