v4.19.13 snapshot.
diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c
new file mode 100644
index 0000000..e0e603a
--- /dev/null
+++ b/drivers/firmware/efi/libstub/random.c
@@ -0,0 +1,192 @@
+/*
+ * Copyright (C) 2016 Linaro Ltd; <ard.biesheuvel@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/efi.h>
+#include <linux/log2.h>
+#include <asm/efi.h>
+
+#include "efistub.h"
+
+struct efi_rng_protocol {
+ efi_status_t (*get_info)(struct efi_rng_protocol *,
+ unsigned long *, efi_guid_t *);
+ efi_status_t (*get_rng)(struct efi_rng_protocol *,
+ efi_guid_t *, unsigned long, u8 *out);
+};
+
+efi_status_t efi_get_random_bytes(efi_system_table_t *sys_table_arg,
+ unsigned long size, u8 *out)
+{
+ efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
+ efi_status_t status;
+ struct efi_rng_protocol *rng;
+
+ status = efi_call_early(locate_protocol, &rng_proto, NULL,
+ (void **)&rng);
+ if (status != EFI_SUCCESS)
+ return status;
+
+ return rng->get_rng(rng, NULL, size, out);
+}
+
+/*
+ * Return the number of slots covered by this entry, i.e., the number of
+ * addresses it covers that are suitably aligned and supply enough room
+ * for the allocation.
+ */
+static unsigned long get_entry_num_slots(efi_memory_desc_t *md,
+ unsigned long size,
+ unsigned long align_shift)
+{
+ unsigned long align = 1UL << align_shift;
+ u64 first_slot, last_slot, region_end;
+
+ if (md->type != EFI_CONVENTIONAL_MEMORY)
+ return 0;
+
+ region_end = min((u64)ULONG_MAX, md->phys_addr + md->num_pages*EFI_PAGE_SIZE - 1);
+
+ first_slot = round_up(md->phys_addr, align);
+ last_slot = round_down(region_end - size + 1, align);
+
+ if (first_slot > last_slot)
+ return 0;
+
+ return ((unsigned long)(last_slot - first_slot) >> align_shift) + 1;
+}
+
+/*
+ * The UEFI memory descriptors have a virtual address field that is only used
+ * when installing the virtual mapping using SetVirtualAddressMap(). Since it
+ * is unused here, we can reuse it to keep track of each descriptor's slot
+ * count.
+ */
+#define MD_NUM_SLOTS(md) ((md)->virt_addr)
+
+efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg,
+ unsigned long size,
+ unsigned long align,
+ unsigned long *addr,
+ 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;
+
+ 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;
+
+ if (align < EFI_ALLOC_ALIGN)
+ align = EFI_ALLOC_ALIGN;
+
+ /* count the suitable slots in each memory map entry */
+ for (map_offset = 0; map_offset < map_size; map_offset += desc_size) {
+ efi_memory_desc_t *md = (void *)memory_map + map_offset;
+ unsigned long slots;
+
+ slots = get_entry_num_slots(md, size, ilog2(align));
+ MD_NUM_SLOTS(md) = slots;
+ total_slots += slots;
+ }
+
+ /* find a random number between 0 and total_slots */
+ target_slot = (total_slots * (u16)random_seed) >> 16;
+
+ /*
+ * target_slot is now a value in the range [0, total_slots), and so
+ * it corresponds with exactly one of the suitable slots we recorded
+ * when iterating over the memory map the first time around.
+ *
+ * So iterate over the memory map again, subtracting the number of
+ * slots of each entry at each iteration, until we have found the entry
+ * that covers our chosen slot. Use the residual value of target_slot
+ * to calculate the randomly chosen address, and allocate it directly
+ * using EFI_ALLOCATE_ADDRESS.
+ */
+ for (map_offset = 0; map_offset < map_size; map_offset += desc_size) {
+ efi_memory_desc_t *md = (void *)memory_map + map_offset;
+ efi_physical_addr_t target;
+ unsigned long pages;
+
+ if (target_slot >= MD_NUM_SLOTS(md)) {
+ target_slot -= MD_NUM_SLOTS(md);
+ continue;
+ }
+
+ target = round_up(md->phys_addr, align) + target_slot * align;
+ pages = round_up(size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE;
+
+ status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
+ EFI_LOADER_DATA, pages, &target);
+ if (status == EFI_SUCCESS)
+ *addr = target;
+ break;
+ }
+
+ efi_call_early(free_pool, memory_map);
+
+ return status;
+}
+
+efi_status_t efi_random_get_seed(efi_system_table_t *sys_table_arg)
+{
+ efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
+ efi_guid_t rng_algo_raw = EFI_RNG_ALGORITHM_RAW;
+ efi_guid_t rng_table_guid = LINUX_EFI_RANDOM_SEED_TABLE_GUID;
+ struct efi_rng_protocol *rng;
+ struct linux_efi_random_seed *seed;
+ efi_status_t status;
+
+ status = efi_call_early(locate_protocol, &rng_proto, NULL,
+ (void **)&rng);
+ if (status != EFI_SUCCESS)
+ return status;
+
+ status = efi_call_early(allocate_pool, EFI_RUNTIME_SERVICES_DATA,
+ sizeof(*seed) + EFI_RANDOM_SEED_SIZE,
+ (void **)&seed);
+ if (status != EFI_SUCCESS)
+ return status;
+
+ status = rng->get_rng(rng, &rng_algo_raw, EFI_RANDOM_SEED_SIZE,
+ seed->bits);
+ if (status == EFI_UNSUPPORTED)
+ /*
+ * Use whatever algorithm we have available if the raw algorithm
+ * is not implemented.
+ */
+ status = rng->get_rng(rng, NULL, EFI_RANDOM_SEED_SIZE,
+ seed->bits);
+
+ if (status != EFI_SUCCESS)
+ goto err_freepool;
+
+ seed->size = EFI_RANDOM_SEED_SIZE;
+ status = efi_call_early(install_configuration_table, &rng_table_guid,
+ seed);
+ if (status != EFI_SUCCESS)
+ goto err_freepool;
+
+ return EFI_SUCCESS;
+
+err_freepool:
+ efi_call_early(free_pool, seed);
+ return status;
+}