efi/libstub: Allocate headspace in efi_get_memory_map()

commit dadb57abc37499f565b23933dbf49b435c3ba8af upstream.

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>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
[bwh: Backported to 3.16:
 - Adjust filenames, context
 - In allocate_new_fdt_and_exit_boot(), only fill memory_map
 - Drop changes to efi_random_alloc()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 8cb09c9d81ef..1431089c54dc 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -117,6 +117,15 @@ typedef struct {
 	u32 imagesize;
 } efi_capsule_header_t;
 
+struct efi_boot_memmap {
+	efi_memory_desc_t	**map;
+	unsigned long		*map_size;
+	unsigned long		*desc_size;
+	u32			*desc_ver;
+	unsigned long		*key_ptr;
+	unsigned long		*buff_size;
+};
+
 /*
  * Allocation types for calls to boottime->allocate_pages.
  */