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 } 140