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/*
* 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.
*
*/
#include <linux/efi.h>
#include <asm/efi.h>
#include <asm/sections.h>
#include "efistub.h"
extern bool __nokaslr;
efi_status_t __init 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
* is a multiple of the minimal segment alignment (SZ_64K)
*/
u32 mask = (MIN_KIMG_ALIGN - 1) & ~(SZ_64K - 1);
u32 offset = !IS_ENABLED(CONFIG_DEBUG_ALIGN_RODATA) ?
(phys_seed >> 32) & mask : TEXT_OFFSET;
/*
* 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;
}
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