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efi/libstub: Allocate headspace in efi_get_memory_map()

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efi_get_memory_map() allocates a buffer to store the memory map that it
retrieves.  This buffer may need to be reused by the client after
ExitBootServices() is called, at which point allocations are not longer
permitted.  To support this usecase, provide the allocated buffer size back
to the client, and allocate some additional headroom to account for any
reasonable growth in the map that is likely to happen between the call to
efi_get_memory_map() and the client reusing the buffer.

Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
This commit is contained in:
Jeffrey Hugo
2016-08-29 14:38:51 -06:00
committed by Matt Fleming
parent 4af9ed578a
commit dadb57abc3
5 changed files with 110 additions and 48 deletions
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12
drivers/firmware/efi/libstub/random.c
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@@ -73,12 +73,20 @@ efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg,
unsigned long random_seed)
{
unsigned long map_size, desc_size, total_slots = 0, target_slot;
unsigned long buff_size;
efi_status_t status;
efi_memory_desc_t *memory_map;
int map_offset;
struct efi_boot_memmap map;
status = efi_get_memory_map(sys_table_arg, &memory_map, &map_size,
&desc_size, NULL, NULL);
map.map = &memory_map;
map.map_size = &map_size;
map.desc_size = &desc_size;
map.desc_ver = NULL;
map.key_ptr = NULL;
map.buff_size = &buff_size;
status = efi_get_memory_map(sys_table_arg, &map);
if (status != EFI_SUCCESS)
return status;