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
18static 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
59efi_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
92u32 __weak code_size;
93
94void 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
120unsigned 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
132void __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