diff options
Diffstat (limited to 'drivers/firmware/efi/libstub/arm64-stub.c')
| -rw-r--r-- | drivers/firmware/efi/libstub/arm64-stub.c | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c new file mode 100644 index 000000000..1b4d465cc --- /dev/null +++ b/drivers/firmware/efi/libstub/arm64-stub.c @@ -0,0 +1,159 @@ +/* + * Copyright (C) 2013, 2014 Linaro Ltd; <roy.franz@linaro.org> + * + * This file implements the EFI boot stub for the arm64 kernel. + * Adapted from ARM version by Mark Salter <msalter@redhat.com> + * + * 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. + * + */ + +/* + * To prevent the compiler from emitting GOT-indirected (and thus absolute) + * references to the section markers, override their visibility as 'hidden' + */ +#pragma GCC visibility push(hidden) +#include <asm/sections.h> +#pragma GCC visibility pop + +#include <linux/efi.h> +#include <asm/efi.h> +#include <asm/memory.h> +#include <asm/sysreg.h> + +#include "efistub.h" + +efi_status_t check_platform_features(efi_system_table_t *sys_table_arg) +{ + u64 tg; + + /* UEFI mandates support for 4 KB granularity, no need to check */ + if (IS_ENABLED(CONFIG_ARM64_4K_PAGES)) + return EFI_SUCCESS; + + tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_TGRAN_SHIFT) & 0xf; + if (tg != ID_AA64MMFR0_TGRAN_SUPPORTED) { + if (IS_ENABLED(CONFIG_ARM64_64K_PAGES)) + pr_efi_err(sys_table_arg, "This 64 KB granular kernel is not supported by your CPU\n"); + else + pr_efi_err(sys_table_arg, "This 16 KB granular kernel is not supported by your CPU\n"); + return EFI_UNSUPPORTED; + } + return EFI_SUCCESS; +} + +efi_status_t handle_kernel_image(efi_system_table_t *sys_table_arg, + 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; + unsigned long kernel_size, kernel_memsize = 0; + void *old_image_addr = (void *)*image_addr; + unsigned long preferred_offset; + u64 phys_seed = 0; + + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { + if (!nokaslr()) { + status = efi_get_random_bytes(sys_table_arg, + sizeof(phys_seed), + (u8 *)&phys_seed); + if (status == EFI_NOT_FOUND) { + pr_efi(sys_table_arg, "EFI_RNG_PROTOCOL unavailable, no randomness supplied\n"); + } else if (status != EFI_SUCCESS) { + pr_efi_err(sys_table_arg, "efi_get_random_bytes() failed\n"); + return status; + } + } else { + pr_efi(sys_table_arg, "KASLR disabled on kernel command line\n"); + } + } + + /* + * The preferred offset of the kernel Image is TEXT_OFFSET bytes beyond + * a 2 MB aligned base, which itself may be lower than dram_base, as + * long as the resulting offset equals or exceeds it. + */ + preferred_offset = round_down(dram_base, MIN_KIMG_ALIGN) + TEXT_OFFSET; + if (preferred_offset < dram_base) + preferred_offset += MIN_KIMG_ALIGN; + + kernel_size = _edata - _text; + kernel_memsize = kernel_size + (_end - _edata); + + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) { + /* + * If CONFIG_DEBUG_ALIGN_RODATA is not set, produce a + * displacement in the interval [0, MIN_KIMG_ALIGN) that + * doesn't violate this kernel's de-facto alignment + * constraints. + */ + u32 mask = (MIN_KIMG_ALIGN - 1) & ~(EFI_KIMG_ALIGN - 1); + u32 offset = !IS_ENABLED(CONFIG_DEBUG_ALIGN_RODATA) ? + (phys_seed >> 32) & mask : TEXT_OFFSET; + + /* + * With CONFIG_RANDOMIZE_TEXT_OFFSET=y, TEXT_OFFSET may not + * be a multiple of EFI_KIMG_ALIGN, and we must ensure that + * we preserve the misalignment of 'offset' relative to + * EFI_KIMG_ALIGN so that statically allocated objects whose + * alignment exceeds PAGE_SIZE appear correctly aligned in + * memory. + */ + offset |= TEXT_OFFSET % EFI_KIMG_ALIGN; + + /* + * If KASLR is enabled, and we have some randomness available, + * locate the kernel at a randomized offset in physical memory. + */ + *reserve_size = kernel_memsize + offset; + status = efi_random_alloc(sys_table_arg, *reserve_size, + MIN_KIMG_ALIGN, reserve_addr, + (u32)phys_seed); + + *image_addr = *reserve_addr + offset; + } else { + /* + * Else, try a straight allocation at the preferred offset. + * This will work around the issue where, if dram_base == 0x0, + * efi_low_alloc() refuses to allocate at 0x0 (to prevent the + * address of the allocation to be mistaken for a FAIL return + * value or a NULL pointer). It will also ensure that, on + * platforms where the [dram_base, dram_base + TEXT_OFFSET) + * interval is partially occupied by the firmware (like on APM + * Mustang), we can still place the kernel at the address + * 'dram_base + TEXT_OFFSET'. + */ + if (*image_addr == preferred_offset) + return EFI_SUCCESS; + + *image_addr = *reserve_addr = preferred_offset; + *reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN); + + status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS, + EFI_LOADER_DATA, + *reserve_size / EFI_PAGE_SIZE, + (efi_physical_addr_t *)reserve_addr); + } + + if (status != EFI_SUCCESS) { + *reserve_size = kernel_memsize + TEXT_OFFSET; + status = efi_low_alloc(sys_table_arg, *reserve_size, + MIN_KIMG_ALIGN, reserve_addr); + + if (status != EFI_SUCCESS) { + pr_efi_err(sys_table_arg, "Failed to relocate kernel\n"); + *reserve_size = 0; + return status; + } + *image_addr = *reserve_addr + TEXT_OFFSET; + } + memcpy((void *)*image_addr, old_image_addr, kernel_size); + + return EFI_SUCCESS; +} |