drivers/firmware/efi/libstub/arm64.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2013, 2014 Linaro Ltd;  <roy.franz@linaro.org>
   4  *
   5  * This file implements the EFI boot stub for the arm64 kernel.
   6  * Adapted from ARM version by Mark Salter <msalter@redhat.com>
   7  */
   8
   9
  10 #include <linux/efi.h>
  11 #include <asm/efi.h>
  12 #include <asm/image.h>
  13 #include <asm/memory.h>
  14 #include <asm/sysreg.h>
  15
  16 #include "efistub.h"
  17
  18 static bool system_needs_vamap(void)
  19 {
  20         const struct efi_smbios_type4_record *record;
  21         const u32 __aligned(1) *socid;
  22         const u8 *version;
  23
  24         /*
  25          * Ampere eMAG, Altra, and Altra Max machines crash in SetTime() if
  26          * SetVirtualAddressMap() has not been called prior. Most Altra systems
  27          * can be identified by the SMCCC soc ID, which is conveniently exposed
  28          * via the type 4 SMBIOS records. Otherwise, test the processor version
  29          * field. eMAG systems all appear to have the processor version field
  30          * set to "eMAG".
  31          */
  32         record = (struct efi_smbios_type4_record *)efi_get_smbios_record(4);
  33         if (!record)
  34                 return false;
  35
  36         socid = (u32 *)record->processor_id;
  37         switch (*socid & 0xffff000f) {
  38                 static char const altra[] = "Ampere(TM) Altra(TM) Processor";
  39                 static char const emag[] = "eMAG";
  40
  41         default:
  42                 version = efi_get_smbios_string(record, processor_version);
  43                 if (!version || (strncmp(version, altra, sizeof(altra) - 1) &&
  44                                  strncmp(version, emag, sizeof(emag) - 1)))
  45                         break;
  46
  47                 fallthrough;
  48
  49         case 0x0a160001:        // Altra
  50         case 0x0a160002:        // Altra Max
  51                 efi_warn("Working around broken SetVirtualAddressMap()\n");
  52                 return true;
  53         }
  54
  55         return false;
  56 }
  57
  58 efi_status_t check_platform_features(void)
  59 {
  60         u64 tg;
  61
  62         /*
  63          * If we have 48 bits of VA space for TTBR0 mappings, we can map the
  64          * UEFI runtime regions 1:1 and so calling SetVirtualAddressMap() is
  65          * unnecessary.
  66          */
  67         if (VA_BITS_MIN >= 48 && !system_needs_vamap())
  68                 efi_novamap = true;
  69
  70         /* UEFI mandates support for 4 KB granularity, no need to check */
  71         if (IS_ENABLED(CONFIG_ARM64_4K_PAGES))
  72                 return EFI_SUCCESS;
  73
  74         tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_EL1_TGRAN_SHIFT) & 0xf;
  75         if (tg < ID_AA64MMFR0_EL1_TGRAN_SUPPORTED_MIN || tg > ID_AA64MMFR0_EL1_TGRAN_SUPPORTED_MAX) {
  76                 if (IS_ENABLED(CONFIG_ARM64_64K_PAGES))
  77                         efi_err("This 64 KB granular kernel is not supported by your CPU\n");
  78                 else
  79                         efi_err("This 16 KB granular kernel is not supported by your CPU\n");
  80                 return EFI_UNSUPPORTED;
  81         }
  82         return EFI_SUCCESS;
  83 }
  84
  85 #ifdef CONFIG_ARM64_WORKAROUND_CLEAN_CACHE
  86 #define DCTYPE  "civac"
  87 #else
  88 #define DCTYPE  "cvau"
  89 #endif
  90
  91 u32 __weak code_size;
  92
  93 void efi_cache_sync_image(unsigned long image_base,
  94                           unsigned long alloc_size)
  95 {
  96         u32 ctr = read_cpuid_effective_cachetype();
  97         u64 lsize = 4 << cpuid_feature_extract_unsigned_field(ctr,
  98                                                 CTR_EL0_DminLine_SHIFT);
  99
 100         /* only perform the cache maintenance if needed for I/D coherency */
 101         if (!(ctr & BIT(CTR_EL0_IDC_SHIFT))) {
 102                 unsigned long base = image_base;
 103                 unsigned long size = code_size;
 104
 105                 do {
 106                         asm("dc " DCTYPE ", %0" :: "r"(base));
 107                         base += lsize;
 108                         size -= lsize;
 109                 } while (size >= lsize);
 110         }
 111
 112         asm("ic ialluis");
 113         dsb(ish);
 114         isb();
 115
 116         efi_remap_image(image_base, alloc_size, code_size);
 117 }
 118
 119 unsigned long __weak primary_entry_offset(void)
 120 {
 121         /*
 122          * By default, we can invoke the kernel via the branch instruction in
 123          * the image header, so offset #0. This will be overridden by the EFI
 124          * stub build that is linked into the core kernel, as in that case, the
 125          * image header may not have been loaded into memory, or may be mapped
 126          * with non-executable permissions.
 127          */
 128        return 0;
 129 }
 130
 131 void __noreturn efi_enter_kernel(unsigned long entrypoint,
 132                                  unsigned long fdt_addr,
 133                                  unsigned long fdt_size)
 134 {
 135         void (* __noreturn enter_kernel)(u64, u64, u64, u64);
 136
 137         enter_kernel = (void *)entrypoint + primary_entry_offset();
 138         enter_kernel(fdt_addr, 0, 0, 0);
 139 }