1 files changed, 37 insertions, 141 deletions

diff --git a/drivers/firmware/efi/libstub/arm32-stub.c b/drivers/firmware/efi/libstub/arm32-stub.c
index d08e5d55838c..4b5b2403b3a0 100644
--- a/drivers/firmware/efi/libstub/arm32-stub.c
+++ b/drivers/firmware/efi/libstub/arm32-stub.c
@@ -113,162 +113,58 @@ void free_screen_info(struct screen_info *si)
 	efi_bs_call(free_pool, si);
 }
 
-static efi_status_t reserve_kernel_base(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_bs_call(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(&map);
-	if (status != EFI_SUCCESS) {
-		efi_err("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:
-			/* Skip soft reserved conventional memory */
-			if (efi_soft_reserve_enabled() &&
-			    (desc->attribute & EFI_MEMORY_SP))
-				continue;
-
-			/*
-			 * 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_bs_call(allocate_pages,
-					     EFI_ALLOCATE_ADDRESS,
-					     EFI_LOADER_DATA,
-					     (end - start) / EFI_PAGE_SIZE,
-					     &start);
-			if (status != EFI_SUCCESS) {
-				efi_err("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_bs_call(free_pool, memory_map);
-	return status;
-}
-
 efi_status_t handle_kernel_image(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)
 {
-	unsigned long kernel_base;
+	const int slack = TEXT_OFFSET - 5 * PAGE_SIZE;
+	int alloc_size = MAX_UNCOMP_KERNEL_SIZE + EFI_PHYS_ALIGN;
+	unsigned long alloc_base, kernel_base;
 	efi_status_t status;
 
-	/* use a 16 MiB aligned base for the decompressed kernel */
-	kernel_base = round_up(dram_base, SZ_16M) + TEXT_OFFSET;
-
 	/*
-	 * Note that some platforms (notably, the Raspberry Pi 2) put
-	 * spin-tables and other pieces of firmware at the base of RAM,
-	 * abusing the fact that the window of TEXT_OFFSET bytes at the
-	 * base of the kernel image is only partially used at the moment.
-	 * (Up to 5 pages are used for the swapper page tables)
+	 * Allocate space for the decompressed kernel as low as possible.
+	 * The region should be 16 MiB aligned, but the first 'slack' bytes
+	 * are not used by Linux, so we allow those to be occupied by the
+	 * firmware.
 	 */
-	status = reserve_kernel_base(kernel_base - 5 * PAGE_SIZE, reserve_addr,
-				     reserve_size);
+	status = efi_low_alloc_above(alloc_size, EFI_PAGE_SIZE, &alloc_base, 0x0);
 	if (status != EFI_SUCCESS) {
 		efi_err("Unable to allocate memory for uncompressed kernel.\n");
 		return status;
 	}
 
-	*image_addr = kernel_base;
+	if ((alloc_base % EFI_PHYS_ALIGN) > slack) {
+		/*
+		 * More than 'slack' bytes are already occupied at the base of
+		 * the allocation, so we need to advance to the next 16 MiB block.
+		 */
+		kernel_base = round_up(alloc_base, EFI_PHYS_ALIGN);
+		efi_info("Free memory starts at 0x%lx, setting kernel_base to 0x%lx\n",
+			 alloc_base, kernel_base);
+	} else {
+		kernel_base = round_down(alloc_base, EFI_PHYS_ALIGN);
+	}
+
+	*reserve_addr = kernel_base + slack;
+	*reserve_size = MAX_UNCOMP_KERNEL_SIZE;
+
+	/* now free the parts that we will not use */
+	if (*reserve_addr > alloc_base) {
+		efi_bs_call(free_pages, alloc_base,
+			    (*reserve_addr - alloc_base) / EFI_PAGE_SIZE);
+		alloc_size -= *reserve_addr - alloc_base;
+	}
+	efi_bs_call(free_pages, *reserve_addr + MAX_UNCOMP_KERNEL_SIZE,
+		    (alloc_size - MAX_UNCOMP_KERNEL_SIZE) / EFI_PAGE_SIZE);
+
+	*image_addr = kernel_base + TEXT_OFFSET;
 	*image_size = 0;
+
+	efi_debug("image addr == 0x%lx, reserve_addr == 0x%lx\n",
+		  *image_addr, *reserve_addr);
+
 	return EFI_SUCCESS;
 }