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->header, 4,
43 						processor_version);
44 		if (!version || (strncmp(version, altra, sizeof(altra) - 1) &&
45 				 strncmp(version, emag, sizeof(emag) - 1)))
46 			break;
47 
48 		fallthrough;
49 
50 	case 0x0a160001:	// Altra
51 	case 0x0a160002:	// Altra Max
52 		efi_warn("Working around broken SetVirtualAddressMap()\n");
53 		return true;
54 	}
55 
56 	return false;
57 }
58 
59 efi_status_t check_platform_features(void)
60 {
61 	u64 tg;
62 
63 	/*
64 	 * If we have 48 bits of VA space for TTBR0 mappings, we can map the
65 	 * UEFI runtime regions 1:1 and so calling SetVirtualAddressMap() is
66 	 * unnecessary.
67 	 */
68 	if (VA_BITS_MIN >= 48 && !system_needs_vamap())
69 		efi_novamap = true;
70 
71 	/* UEFI mandates support for 4 KB granularity, no need to check */
72 	if (IS_ENABLED(CONFIG_ARM64_4K_PAGES))
73 		return EFI_SUCCESS;
74 
75 	tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_EL1_TGRAN_SHIFT) & 0xf;
76 	if (tg < ID_AA64MMFR0_EL1_TGRAN_SUPPORTED_MIN || tg > ID_AA64MMFR0_EL1_TGRAN_SUPPORTED_MAX) {
77 		if (IS_ENABLED(CONFIG_ARM64_64K_PAGES))
78 			efi_err("This 64 KB granular kernel is not supported by your CPU\n");
79 		else
80 			efi_err("This 16 KB granular kernel is not supported by your CPU\n");
81 		return EFI_UNSUPPORTED;
82 	}
83 	return EFI_SUCCESS;
84 }
85 
86 #ifdef CONFIG_ARM64_WORKAROUND_CLEAN_CACHE
87 #define DCTYPE	"civac"
88 #else
89 #define DCTYPE	"cvau"
90 #endif
91 
92 u32 __weak code_size;
93 
94 void efi_cache_sync_image(unsigned long image_base,
95 			  unsigned long alloc_size)
96 {
97 	u32 ctr = read_cpuid_effective_cachetype();
98 	u64 lsize = 4 << cpuid_feature_extract_unsigned_field(ctr,
99 						CTR_EL0_DminLine_SHIFT);
100 
101 	/* only perform the cache maintenance if needed for I/D coherency */
102 	if (!(ctr & BIT(CTR_EL0_IDC_SHIFT))) {
103 		unsigned long base = image_base;
104 		unsigned long size = code_size;
105 
106 		do {
107 			asm("dc " DCTYPE ", %0" :: "r"(base));
108 			base += lsize;
109 			size -= lsize;
110 		} while (size >= lsize);
111 	}
112 
113 	asm("ic ialluis");
114 	dsb(ish);
115 	isb();
116 
117 	efi_remap_image(image_base, alloc_size, code_size);
118 }
119 
120 unsigned long __weak primary_entry_offset(void)
121 {
122 	/*
123 	 * By default, we can invoke the kernel via the branch instruction in
124 	 * the image header, so offset #0. This will be overridden by the EFI
125 	 * stub build that is linked into the core kernel, as in that case, the
126 	 * image header may not have been loaded into memory, or may be mapped
127 	 * with non-executable permissions.
128 	 */
129        return 0;
130 }
131 
132 void __noreturn efi_enter_kernel(unsigned long entrypoint,
133 				 unsigned long fdt_addr,
134 				 unsigned long fdt_size)
135 {
136 	void (* __noreturn enter_kernel)(u64, u64, u64, u64);
137 
138 	enter_kernel = (void *)entrypoint + primary_entry_offset();
139 	enter_kernel(fdt_addr, 0, 0, 0);
140 }
141