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
  13 /*
  14  * To prevent the compiler from emitting GOT-indirected (and thus absolute)
  15  * references to the section markers, override their visibility as 'hidden'
  16  */
  17 #pragma GCC visibility push(hidden)
  18 #include <asm/sections.h>
  19 #pragma GCC visibility pop
  20
  21 #include <linux/efi.h>
  22 #include <asm/efi.h>
  23 #include <asm/sysreg.h>
  24
  25 #include "efistub.h"
  26
  27 efi_status_t check_platform_features(efi_system_table_t *sys_table_arg)
  28 {
  29         u64 tg;
  30
  31         /* UEFI mandates support for 4 KB granularity, no need to check */
  32         if (IS_ENABLED(CONFIG_ARM64_4K_PAGES))
  33                 return EFI_SUCCESS;
  34
  35         tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_TGRAN_SHIFT) & 0xf;
  36         if (tg != ID_AA64MMFR0_TGRAN_SUPPORTED) {
  37                 if (IS_ENABLED(CONFIG_ARM64_64K_PAGES))
  38                         pr_efi_err(sys_table_arg, "This 64 KB granular kernel is not supported by your CPU\n");
  39                 else
  40                         pr_efi_err(sys_table_arg, "This 16 KB granular kernel is not supported by your CPU\n");
  41                 return EFI_UNSUPPORTED;
  42         }
  43         return EFI_SUCCESS;
  44 }
  45
  46 efi_status_t handle_kernel_image(efi_system_table_t *sys_table_arg,
  47                                  unsigned long *image_addr,
  48                                  unsigned long *image_size,
  49                                  unsigned long *reserve_addr,
  50                                  unsigned long *reserve_size,
  51                                  unsigned long dram_base,
  52                                  efi_loaded_image_t *image)
  53 {
  54         efi_status_t status;
  55         unsigned long kernel_size, kernel_memsize = 0;
  56         void *old_image_addr = (void *)*image_addr;
  57         unsigned long preferred_offset;
  58         u64 phys_seed = 0;
  59
  60         if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
  61                 if (!nokaslr()) {
  62                         status = efi_get_random_bytes(sys_table_arg,
  63                                                       sizeof(phys_seed),
  64                                                       (u8 *)&phys_seed);
  65                         if (status == EFI_NOT_FOUND) {
  66                                 pr_efi(sys_table_arg, "EFI_RNG_PROTOCOL unavailable, no randomness supplied\n");
  67                         } else if (status != EFI_SUCCESS) {
  68                                 pr_efi_err(sys_table_arg, "efi_get_random_bytes() failed\n");
  69                                 return status;
  70                         }
  71                 } else {
  72                         pr_efi(sys_table_arg, "KASLR disabled on kernel command line\n");
  73                 }
  74         }
  75
  76         /*
  77          * The preferred offset of the kernel Image is TEXT_OFFSET bytes beyond
  78          * a 2 MB aligned base, which itself may be lower than dram_base, as
  79          * long as the resulting offset equals or exceeds it.
  80          */
  81         preferred_offset = round_down(dram_base, MIN_KIMG_ALIGN) + TEXT_OFFSET;
  82         if (preferred_offset < dram_base)
  83                 preferred_offset += MIN_KIMG_ALIGN;
  84
  85         kernel_size = _edata - _text;
  86         kernel_memsize = kernel_size + (_end - _edata);
  87
  88         if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) {
  89                 /*
  90                  * If CONFIG_DEBUG_ALIGN_RODATA is not set, produce a
  91                  * displacement in the interval [0, MIN_KIMG_ALIGN) that
  92                  * is a multiple of the minimal segment alignment (SZ_64K)
  93                  */
  94                 u32 mask = (MIN_KIMG_ALIGN - 1) & ~(SZ_64K - 1);
  95                 u32 offset = !IS_ENABLED(CONFIG_DEBUG_ALIGN_RODATA) ?
  96                              (phys_seed >> 32) & mask : TEXT_OFFSET;
  97
  98                 /*
  99                  * If KASLR is enabled, and we have some randomness available,
 100                  * locate the kernel at a randomized offset in physical memory.
 101                  */
 102                 *reserve_size = kernel_memsize + offset;
 103                 status = efi_random_alloc(sys_table_arg, *reserve_size,
 104                                           MIN_KIMG_ALIGN, reserve_addr,
 105                                           (u32)phys_seed);
 106
 107                 *image_addr = *reserve_addr + offset;
 108         } else {
 109                 /*
 110                  * Else, try a straight allocation at the preferred offset.
 111                  * This will work around the issue where, if dram_base == 0x0,
 112                  * efi_low_alloc() refuses to allocate at 0x0 (to prevent the
 113                  * address of the allocation to be mistaken for a FAIL return
 114                  * value or a NULL pointer). It will also ensure that, on
 115                  * platforms where the [dram_base, dram_base + TEXT_OFFSET)
 116                  * interval is partially occupied by the firmware (like on APM
 117                  * Mustang), we can still place the kernel at the address
 118                  * 'dram_base + TEXT_OFFSET'.
 119                  */
 120                 if (*image_addr == preferred_offset)
 121                         return EFI_SUCCESS;
 122
 123                 *image_addr = *reserve_addr = preferred_offset;
 124                 *reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN);
 125
 126                 status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
 127                                         EFI_LOADER_DATA,
 128                                         *reserve_size / EFI_PAGE_SIZE,
 129                                         (efi_physical_addr_t *)reserve_addr);
 130         }
 131
 132         if (status != EFI_SUCCESS) {
 133                 *reserve_size = kernel_memsize + TEXT_OFFSET;
 134                 status = efi_low_alloc(sys_table_arg, *reserve_size,
 135                                        MIN_KIMG_ALIGN, reserve_addr);
 136
 137                 if (status != EFI_SUCCESS) {
 138                         pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
 139                         *reserve_size = 0;
 140                         return status;
 141                 }
 142                 *image_addr = *reserve_addr + TEXT_OFFSET;
 143         }
 144         memcpy((void *)*image_addr, old_image_addr, kernel_size);
 145
 146         return EFI_SUCCESS;
 147 }