From c0249238feefbbb99d517d06ace4338393901b67 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Thu, 12 Nov 2020 15:42:27 +0100 Subject: [PATCH] efi: arm: reduce minimum alignment of uncompressed kernel Now that we reduced the minimum relative alignment between PHYS_OFFSET and PAGE_OFFSET to 2 MiB, we can take this into account when allocating memory for the decompressed kernel when booting via EFI. This minimizes the amount of unusable memory we may end up with due to the base of DRAM being occupied by firmware. Signed-off-by: Ard Biesheuvel --- arch/arm/include/asm/efi.h | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/arch/arm/include/asm/efi.h b/arch/arm/include/asm/efi.h index e9a06e1..1536805 100644 --- a/arch/arm/include/asm/efi.h +++ b/arch/arm/include/asm/efi.h @@ -66,13 +66,12 @@ static inline void efifb_setup_from_dmi(struct screen_info *si, const char *opt) #define MAX_UNCOMP_KERNEL_SIZE SZ_32M /* - * phys-to-virt patching requires that the physical to virtual offset fits - * into the immediate field of an add/sub instruction, which comes down to the - * 24 least significant bits being zero, and so the offset should be a multiple - * of 16 MB. Since PAGE_OFFSET itself is a multiple of 16 MB, the physical - * base should be aligned to 16 MB as well. + * phys-to-virt patching requires that the physical to virtual offset is a + * multiple of 2 MiB. However, using an alignment smaller than TEXT_OFFSET + * here throws off the memory allocation logic, so let's use the lowest power + * of two greater than 2 MiB and greater than TEXT_OFFSET. */ -#define EFI_PHYS_ALIGN SZ_16M +#define EFI_PHYS_ALIGN max(SZ_2M, roundup_pow_of_two(TEXT_OFFSET)) /* on ARM, the FDT should be located in a lowmem region */ static inline unsigned long efi_get_max_fdt_addr(unsigned long image_addr) @@ -83,7 +82,7 @@ static inline unsigned long efi_get_max_fdt_addr(unsigned long image_addr) /* on ARM, the initrd should be loaded in a lowmem region */ static inline unsigned long efi_get_max_initrd_addr(unsigned long image_addr) { - return round_down(image_addr, EFI_PHYS_ALIGN) + SZ_512M; + return round_down(image_addr, SZ_4M) + SZ_512M; } struct efi_arm_entry_state { -- 2.7.4