drivers/firmware/efi/libstub/arm64-stub.c

   1 /*
   2  * Copyright (C) 2013, 2014 Linaro Ltd;  <roy.franz@linaro.org>
   3  *
   4  * This file implements the EFI boot stub for the arm64 kernel.
   5  * Adapted from ARM version by Mark Salter <msalter@redhat.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  */
  12 #include <linux/efi.h>
  13 #include <asm/efi.h>
  14 #include <asm/sections.h>
  15 #include <asm/sysreg.h>
  16
  17 #include "efistub.h"
  18
  19 efi_status_t check_platform_features(efi_system_table_t *sys_table_arg)
  20 {
  21         u64 tg;
  22
  23         /* UEFI mandates support for 4 KB granularity, no need to check */
  24         if (IS_ENABLED(CONFIG_ARM64_4K_PAGES))
  25                 return EFI_SUCCESS;
  26
  27         tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_TGRAN_SHIFT) & 0xf;
  28         if (tg != ID_AA64MMFR0_TGRAN_SUPPORTED) {
  29                 if (IS_ENABLED(CONFIG_ARM64_64K_PAGES))
  30                         pr_efi_err(sys_table_arg, "This 64 KB granular kernel is not supported by your CPU\n");
  31                 else
  32                         pr_efi_err(sys_table_arg, "This 16 KB granular kernel is not supported by your CPU\n");
  33                 return EFI_UNSUPPORTED;
  34         }
  35         return EFI_SUCCESS;
  36 }
  37
  38 efi_status_t handle_kernel_image(efi_system_table_t *sys_table_arg,
  39                                  unsigned long *image_addr,
  40                                  unsigned long *image_size,
  41                                  unsigned long *reserve_addr,
  42                                  unsigned long *reserve_size,
  43                                  unsigned long dram_base,
  44                                  efi_loaded_image_t *image)
  45 {
  46         efi_status_t status;
  47         unsigned long kernel_size, kernel_memsize = 0;
  48         void *old_image_addr = (void *)*image_addr;
  49         unsigned long preferred_offset;
  50         u64 phys_seed = 0;
  51
  52         if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
  53                 if (!nokaslr()) {
  54                         status = efi_get_random_bytes(sys_table_arg,
  55                                                       sizeof(phys_seed),
  56                                                       (u8 *)&phys_seed);
  57                         if (status == EFI_NOT_FOUND) {
  58                                 pr_efi(sys_table_arg, "EFI_RNG_PROTOCOL unavailable, no randomness supplied\n");
  59                         } else if (status != EFI_SUCCESS) {
  60                                 pr_efi_err(sys_table_arg, "efi_get_random_bytes() failed\n");
  61                                 return status;
  62                         }
  63                 } else {
  64                         pr_efi(sys_table_arg, "KASLR disabled on kernel command line\n");
  65                 }
  66         }
  67
  68         /*
  69          * The preferred offset of the kernel Image is TEXT_OFFSET bytes beyond
  70          * a 2 MB aligned base, which itself may be lower than dram_base, as
  71          * long as the resulting offset equals or exceeds it.
  72          */
  73         preferred_offset = round_down(dram_base, MIN_KIMG_ALIGN) + TEXT_OFFSET;
  74         if (preferred_offset < dram_base)
  75                 preferred_offset += MIN_KIMG_ALIGN;
  76
  77         kernel_size = _edata - _text;
  78         kernel_memsize = kernel_size + (_end - _edata);
  79
  80         if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) {
  81                 /*
  82                  * If CONFIG_DEBUG_ALIGN_RODATA is not set, produce a
  83                  * displacement in the interval [0, MIN_KIMG_ALIGN) that
  84                  * is a multiple of the minimal segment alignment (SZ_64K)
  85                  */
  86                 u32 mask = (MIN_KIMG_ALIGN - 1) & ~(SZ_64K - 1);
  87                 u32 offset = !IS_ENABLED(CONFIG_DEBUG_ALIGN_RODATA) ?
  88                              (phys_seed >> 32) & mask : TEXT_OFFSET;
  89
  90                 /*
  91                  * If KASLR is enabled, and we have some randomness available,
  92                  * locate the kernel at a randomized offset in physical memory.
  93                  */
  94                 *reserve_size = kernel_memsize + offset;
  95                 status = efi_random_alloc(sys_table_arg, *reserve_size,
  96                                           MIN_KIMG_ALIGN, reserve_addr,
  97                                           (u32)phys_seed);
  98
  99                 *image_addr = *reserve_addr + offset;
 100         } else {
 101                 /*
 102                  * Else, try a straight allocation at the preferred offset.
 103                  * This will work around the issue where, if dram_base == 0x0,
 104                  * efi_low_alloc() refuses to allocate at 0x0 (to prevent the
 105                  * address of the allocation to be mistaken for a FAIL return
 106                  * value or a NULL pointer). It will also ensure that, on
 107                  * platforms where the [dram_base, dram_base + TEXT_OFFSET)
 108                  * interval is partially occupied by the firmware (like on APM
 109                  * Mustang), we can still place the kernel at the address
 110                  * 'dram_base + TEXT_OFFSET'.
 111                  */
 112                 if (*image_addr == preferred_offset)
 113                         return EFI_SUCCESS;
 114
 115                 *image_addr = *reserve_addr = preferred_offset;
 116                 *reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN);
 117
 118                 status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
 119                                         EFI_LOADER_DATA,
 120                                         *reserve_size / EFI_PAGE_SIZE,
 121                                         (efi_physical_addr_t *)reserve_addr);
 122         }
 123
 124         if (status != EFI_SUCCESS) {
 125                 *reserve_size = kernel_memsize + TEXT_OFFSET;
 126                 status = efi_low_alloc(sys_table_arg, *reserve_size,
 127                                        MIN_KIMG_ALIGN, reserve_addr);
 128
 129                 if (status != EFI_SUCCESS) {
 130                         pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
 131                         *reserve_size = 0;
 132                         return status;
 133                 }
 134                 *image_addr = *reserve_addr + TEXT_OFFSET;
 135         }
 136         memcpy((void *)*image_addr, old_image_addr, kernel_size);
 137
 138         return EFI_SUCCESS;
 139 }