1 files changed, 249 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/arm32-stub.c b/drivers/firmware/efi/libstub/arm32-stub.c
new file mode 100644
index 000000000..becbda445
--- /dev/null
+++ b/drivers/firmware/efi/libstub/arm32-stub.c
@@ -0,0 +1,249 @@
+/*
+ * Copyright (C) 2013 Linaro Ltd;  <roy.franz@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 <asm/efi.h>
+
+#include "efistub.h"
+
+efi_status_t check_platform_features(efi_system_table_t *sys_table_arg)
+{
+	int block;
+
+	/* non-LPAE kernels can run anywhere */
+	if (!IS_ENABLED(CONFIG_ARM_LPAE))
+		return EFI_SUCCESS;
+
+	/* LPAE kernels need compatible hardware */
+	block = cpuid_feature_extract(CPUID_EXT_MMFR0, 0);
+	if (block < 5) {
+		pr_efi_err(sys_table_arg, "This LPAE kernel is not supported by your CPU\n");
+		return EFI_UNSUPPORTED;
+	}
+	return EFI_SUCCESS;
+}
+
+static efi_guid_t screen_info_guid = LINUX_EFI_ARM_SCREEN_INFO_TABLE_GUID;
+
+struct screen_info *alloc_screen_info(efi_system_table_t *sys_table_arg)
+{
+	struct screen_info *si;
+	efi_status_t status;
+
+	/*
+	 * Unlike on arm64, where we can directly fill out the screen_info
+	 * structure from the stub, we need to allocate a buffer to hold
+	 * its contents while we hand over to the kernel proper from the
+	 * decompressor.
+	 */
+	status = efi_call_early(allocate_pool, EFI_RUNTIME_SERVICES_DATA,
+				sizeof(*si), (void **)&si);
+
+	if (status != EFI_SUCCESS)
+		return NULL;
+
+	status = efi_call_early(install_configuration_table,
+				&screen_info_guid, si);
+	if (status == EFI_SUCCESS)
+		return si;
+
+	efi_call_early(free_pool, si);
+	return NULL;
+}
+
+void free_screen_info(efi_system_table_t *sys_table_arg, struct screen_info *si)
+{
+	if (!si)
+		return;
+
+	efi_call_early(install_configuration_table, &screen_info_guid, NULL);
+	efi_call_early(free_pool, si);
+}
+
+static efi_status_t reserve_kernel_base(efi_system_table_t *sys_table_arg,
+					unsigned long dram_base,
+					unsigned long *reserve_addr,
+					unsigned long *reserve_size)
+{
+	efi_physical_addr_t alloc_addr;
+	efi_memory_desc_t *memory_map;
+	unsigned long nr_pages, map_size, desc_size, buff_size;
+	efi_status_t status;
+	unsigned long l;
+
+	struct efi_boot_memmap map = {
+		.map		= &memory_map,
+		.map_size	= &map_size,
+		.desc_size	= &desc_size,
+		.desc_ver	= NULL,
+		.key_ptr	= NULL,
+		.buff_size	= &buff_size,
+	};
+
+	/*
+	 * Reserve memory for the uncompressed kernel image. This is
+	 * all that prevents any future allocations from conflicting
+	 * with the kernel. Since we can't tell from the compressed
+	 * image how much DRAM the kernel actually uses (due to BSS
+	 * size uncertainty) we allocate the maximum possible size.
+	 * Do this very early, as prints can cause memory allocations
+	 * that may conflict with this.
+	 */
+	alloc_addr = dram_base + MAX_UNCOMP_KERNEL_SIZE;
+	nr_pages = MAX_UNCOMP_KERNEL_SIZE / EFI_PAGE_SIZE;
+	status = efi_call_early(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,
+				EFI_BOOT_SERVICES_DATA, nr_pages, &alloc_addr);
+	if (status == EFI_SUCCESS) {
+		if (alloc_addr == dram_base) {
+			*reserve_addr = alloc_addr;
+			*reserve_size = MAX_UNCOMP_KERNEL_SIZE;
+			return EFI_SUCCESS;
+		}
+		/*
+		 * If we end up here, the allocation succeeded but starts below
+		 * dram_base. This can only occur if the real base of DRAM is
+		 * not a multiple of 128 MB, in which case dram_base will have
+		 * been rounded up. Since this implies that a part of the region
+		 * was already occupied, we need to fall through to the code
+		 * below to ensure that the existing allocations don't conflict.
+		 * For this reason, we use EFI_BOOT_SERVICES_DATA above and not
+		 * EFI_LOADER_DATA, which we wouldn't able to distinguish from
+		 * allocations that we want to disallow.
+		 */
+	}
+
+	/*
+	 * If the allocation above failed, we may still be able to proceed:
+	 * if the only allocations in the region are of types that will be
+	 * released to the OS after ExitBootServices(), the decompressor can
+	 * safely overwrite them.
+	 */
+	status = efi_get_memory_map(sys_table_arg, &map);
+	if (status != EFI_SUCCESS) {
+		pr_efi_err(sys_table_arg,
+			   "reserve_kernel_base(): Unable to retrieve memory map.\n");
+		return status;
+	}
+
+	for (l = 0; l < map_size; l += desc_size) {
+		efi_memory_desc_t *desc;
+		u64 start, end;
+
+		desc = (void *)memory_map + l;
+		start = desc->phys_addr;
+		end = start + desc->num_pages * EFI_PAGE_SIZE;
+
+		/* Skip if entry does not intersect with region */
+		if (start >= dram_base + MAX_UNCOMP_KERNEL_SIZE ||
+		    end <= dram_base)
+			continue;
+
+		switch (desc->type) {
+		case EFI_BOOT_SERVICES_CODE:
+		case EFI_BOOT_SERVICES_DATA:
+			/* Ignore types that are released to the OS anyway */
+			continue;
+
+		case EFI_CONVENTIONAL_MEMORY:
+			/*
+			 * Reserve the intersection between this entry and the
+			 * region.
+			 */
+			start = max(start, (u64)dram_base);
+			end = min(end, (u64)dram_base + MAX_UNCOMP_KERNEL_SIZE);
+
+			status = efi_call_early(allocate_pages,
+						EFI_ALLOCATE_ADDRESS,
+						EFI_LOADER_DATA,
+						(end - start) / EFI_PAGE_SIZE,
+						&start);
+			if (status != EFI_SUCCESS) {
+				pr_efi_err(sys_table_arg,
+					"reserve_kernel_base(): alloc failed.\n");
+				goto out;
+			}
+			break;
+
+		case EFI_LOADER_CODE:
+		case EFI_LOADER_DATA:
+			/*
+			 * These regions may be released and reallocated for
+			 * another purpose (including EFI_RUNTIME_SERVICE_DATA)
+			 * at any time during the execution of the OS loader,
+			 * so we cannot consider them as safe.
+			 */
+		default:
+			/*
+			 * Treat any other allocation in the region as unsafe */
+			status = EFI_OUT_OF_RESOURCES;
+			goto out;
+		}
+	}
+
+	status = EFI_SUCCESS;
+out:
+	efi_call_early(free_pool, memory_map);
+	return status;
+}
+
+efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
+				 unsigned long *image_addr,
+				 unsigned long *image_size,
+				 unsigned long *reserve_addr,
+				 unsigned long *reserve_size,
+				 unsigned long dram_base,
+				 efi_loaded_image_t *image)
+{
+	efi_status_t status;
+
+	/*
+	 * Verify that the DRAM base address is compatible with the ARM
+	 * boot protocol, which determines the base of DRAM by masking
+	 * off the low 27 bits of the address at which the zImage is
+	 * loaded. These assumptions are made by the decompressor,
+	 * before any memory map is available.
+	 */
+	dram_base = round_up(dram_base, SZ_128M);
+
+	status = reserve_kernel_base(sys_table, dram_base, reserve_addr,
+				     reserve_size);
+	if (status != EFI_SUCCESS) {
+		pr_efi_err(sys_table, "Unable to allocate memory for uncompressed kernel.\n");
+		return status;
+	}
+
+	/*
+	 * Relocate the zImage, so that it appears in the lowest 128 MB
+	 * memory window.
+	 */
+	*image_size = image->image_size;
+	status = efi_relocate_kernel(sys_table, image_addr, *image_size,
+				     *image_size,
+				     dram_base + MAX_UNCOMP_KERNEL_SIZE, 0);
+	if (status != EFI_SUCCESS) {
+		pr_efi_err(sys_table, "Failed to relocate kernel.\n");
+		efi_free(sys_table, *reserve_size, *reserve_addr);
+		*reserve_size = 0;
+		return status;
+	}
+
+	/*
+	 * Check to see if we were able to allocate memory low enough
+	 * in memory. The kernel determines the base of DRAM from the
+	 * address at which the zImage is loaded.
+	 */
+	if (*image_addr + *image_size > dram_base + ZIMAGE_OFFSET_LIMIT) {
+		pr_efi_err(sys_table, "Failed to relocate kernel, no low memory available.\n");
+		efi_free(sys_table, *reserve_size, *reserve_addr);
+		*reserve_size = 0;
+		efi_free(sys_table, *image_size, *image_addr);
+		*image_size = 0;
+		return EFI_LOAD_ERROR;
+	}
+	return EFI_SUCCESS;
+}