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// SPDX-License-Identifier: GPL-2.0
/*
* 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>
*/
#include <linux/efi.h>
#include <asm/efi.h>
#include <asm/memory.h>
#include <asm/sections.h>
#include "efistub.h"
/*
* Distro versions of GRUB may ignore the BSS allocation entirely (i.e., fail
* to provide space, and fail to zero it). Check for this condition by double
* checking that the first and the last byte of the image are covered by the
* same EFI memory map entry.
*/
static bool check_image_region(u64 base, u64 size)
{
struct efi_boot_memmap *map;
efi_status_t status;
bool ret = false;
int map_offset;
status = efi_get_memory_map(&map, false);
if (status != EFI_SUCCESS)
return false;
for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) {
efi_memory_desc_t *md = (void *)map->map + map_offset;
u64 end = md->phys_addr + md->num_pages * EFI_PAGE_SIZE;
/*
* Find the region that covers base, and return whether
* it covers base+size bytes.
*/
if (base >= md->phys_addr && base < end) {
ret = (base + size) <= end;
break;
}
}
efi_bs_call(free_pool, map);
return ret;
}
efi_status_t handle_kernel_image(unsigned long *image_addr,
unsigned long *image_size,
unsigned long *reserve_addr,
unsigned long *reserve_size,
efi_loaded_image_t *image,
efi_handle_t image_handle)
{
efi_status_t status;
unsigned long kernel_size, kernel_codesize, kernel_memsize;
u32 phys_seed = 0;
u64 min_kimg_align = efi_get_kimg_min_align();
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
efi_guid_t li_fixed_proto = LINUX_EFI_LOADED_IMAGE_FIXED_GUID;
void *p;
if (efi_nokaslr) {
efi_info("KASLR disabled on kernel command line\n");
} else if (efi_bs_call(handle_protocol, image_handle,
&li_fixed_proto, &p) == EFI_SUCCESS) {
efi_info("Image placement fixed by loader\n");
} else {
status = efi_get_random_bytes(sizeof(phys_seed),
(u8 *)&phys_seed);
if (status == EFI_NOT_FOUND) {
efi_info("EFI_RNG_PROTOCOL unavailable\n");
efi_nokaslr = true;
} else if (status != EFI_SUCCESS) {
efi_err("efi_get_random_bytes() failed (0x%lx)\n",
status);
efi_nokaslr = true;
}
}
}
if (image->image_base != _text) {
efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n");
image->image_base = _text;
}
if (!IS_ALIGNED((u64)_text, SEGMENT_ALIGN))
efi_err("FIRMWARE BUG: kernel image not aligned on %dk boundary\n",
SEGMENT_ALIGN >> 10);
kernel_size = _edata - _text;
kernel_codesize = __inittext_end - _text;
kernel_memsize = kernel_size + (_end - _edata);
*reserve_size = kernel_memsize;
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) {
/*
* If KASLR is enabled, and we have some randomness available,
* locate the kernel at a randomized offset in physical memory.
*/
status = efi_random_alloc(*reserve_size, min_kimg_align,
reserve_addr, phys_seed,
EFI_LOADER_CODE);
if (status != EFI_SUCCESS)
efi_warn("efi_random_alloc() failed: 0x%lx\n", status);
} else {
status = EFI_OUT_OF_RESOURCES;
}
if (status != EFI_SUCCESS) {
if (!check_image_region((u64)_text, kernel_memsize)) {
efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n");
} else if (IS_ALIGNED((u64)_text, min_kimg_align) &&
(u64)_end < EFI_ALLOC_LIMIT) {
/*
* Just execute from wherever we were loaded by the
* UEFI PE/COFF loader if the placement is suitable.
*/
*image_addr = (u64)_text;
*reserve_size = 0;
return EFI_SUCCESS;
}
status = efi_allocate_pages_aligned(*reserve_size, reserve_addr,
ULONG_MAX, min_kimg_align,
EFI_LOADER_CODE);
if (status != EFI_SUCCESS) {
efi_err("Failed to relocate kernel\n");
*reserve_size = 0;
return status;
}
}
*image_addr = *reserve_addr;
memcpy((void *)*image_addr, _text, kernel_size);
caches_clean_inval_pou(*image_addr, *image_addr + kernel_codesize);
efi_remap_image(*image_addr, *reserve_size, kernel_codesize);
return EFI_SUCCESS;
}
asmlinkage void primary_entry(void);
unsigned long primary_entry_offset(void)
{
/*
* When built as part of the kernel, the EFI stub cannot branch to the
* kernel proper via the image header, as the PE/COFF header is
* strictly not part of the in-memory presentation of the image, only
* of the file representation. So instead, we need to jump to the
* actual entrypoint in the .text region of the image.
*/
return (char *)primary_entry - _text;
}
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