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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2015-01-08 17:51:47 +0000
committerMatt Fleming <matt.fleming@intel.com>2015-01-20 22:13:33 +0000
commitd1a8d66b9177105e898e73716f97eb61842c457a (patch)
tree743fa621077ce787e58a98d0b9a9b803df25f2b3 /drivers/firmware/efi
parent86d68a58d00db3770735b5919ef2c6b12d7f06f3 (diff)
efi/libstub: Call get_memory_map() to obtain map and desc sizes
This fixes two minor issues in the implementation of get_memory_map(): - Currently, it assumes that sizeof(efi_memory_desc_t) == desc_size, which is usually true, but not mandated by the spec. (This was added intentionally to allow future additions to the definition of efi_memory_desc_t). The way the loop is implemented currently, the added slack space may be insufficient if desc_size is larger, which in some corner cases could result in the loop never terminating. - It allocates 32 efi_memory_desc_t entries first (again, using the size of the struct instead of desc_size), and frees and reallocates if it turns out to be insufficient. Few implementations of UEFI have such small memory maps, which results in a unnecessary allocate/free pair on each invocation. Fix this by calling the get_memory_map() boot service first with a '0' input value for map size to retrieve the map size and desc size from the firmware and only then perform the allocation, using desc_size rather than sizeof(efi_memory_desc_t). Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Diffstat (limited to 'drivers/firmware/efi')
-rw-r--r--drivers/firmware/efi/libstub/efi-stub-helper.c16
1 files changed, 10 insertions, 6 deletions
diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index 9bd9fbb5bea8..d073e3946383 100644
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -66,25 +66,29 @@ efi_status_t efi_get_memory_map(efi_system_table_t *sys_table_arg,
unsigned long key;
u32 desc_version;
- *map_size = sizeof(*m) * 32;
-again:
+ *map_size = 0;
+ *desc_size = 0;
+ key = 0;
+ status = efi_call_early(get_memory_map, map_size, NULL,
+ &key, desc_size, &desc_version);
+ if (status != EFI_BUFFER_TOO_SMALL)
+ return EFI_LOAD_ERROR;
+
/*
* Add an additional efi_memory_desc_t because we're doing an
* allocation which may be in a new descriptor region.
*/
- *map_size += sizeof(*m);
+ *map_size += *desc_size;
status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
*map_size, (void **)&m);
if (status != EFI_SUCCESS)
goto fail;
- *desc_size = 0;
- key = 0;
status = efi_call_early(get_memory_map, map_size, m,
&key, desc_size, &desc_version);
if (status == EFI_BUFFER_TOO_SMALL) {
efi_call_early(free_pool, m);
- goto again;
+ return EFI_LOAD_ERROR;
}
if (status != EFI_SUCCESS)