From d1a8d66b9177105e898e73716f97eb61842c457a Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Thu, 8 Jan 2015 17:51:47 +0000 Subject: 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 Signed-off-by: Matt Fleming --- drivers/firmware/efi/libstub/efi-stub-helper.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) (limited to 'drivers/firmware') 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) -- cgit v1.2.3