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/memory.h>
13 #include <asm/sysreg.h>
14
15 #include "efistub.h"
16
system_needs_vamap(void)17 static bool system_needs_vamap(void)
18 {
19 const u8 *type1_family = efi_get_smbios_string(1, family);
20
21 /*
22 * Ampere eMAG, Altra, and Altra Max machines crash in SetTime() if
23 * SetVirtualAddressMap() has not been called prior.
24 */
25 if (!type1_family || (
26 strcmp(type1_family, "eMAG") &&
27 strcmp(type1_family, "Altra") &&
28 strcmp(type1_family, "Altra Max")))
29 return false;
30
31 efi_warn("Working around broken SetVirtualAddressMap()\n");
32 return true;
33 }
34
check_platform_features(void)35 efi_status_t check_platform_features(void)
36 {
37 u64 tg;
38
39 /*
40 * If we have 48 bits of VA space for TTBR0 mappings, we can map the
41 * UEFI runtime regions 1:1 and so calling SetVirtualAddressMap() is
42 * unnecessary.
43 */
44 if (VA_BITS_MIN >= 48 && !system_needs_vamap())
45 efi_novamap = true;
46
47 /* UEFI mandates support for 4 KB granularity, no need to check */
48 if (IS_ENABLED(CONFIG_ARM64_4K_PAGES))
49 return EFI_SUCCESS;
50
51 tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_EL1_TGRAN_SHIFT) & 0xf;
52 if (tg < ID_AA64MMFR0_EL1_TGRAN_SUPPORTED_MIN || tg > ID_AA64MMFR0_EL1_TGRAN_SUPPORTED_MAX) {
53 if (IS_ENABLED(CONFIG_ARM64_64K_PAGES))
54 efi_err("This 64 KB granular kernel is not supported by your CPU\n");
55 else
56 efi_err("This 16 KB granular kernel is not supported by your CPU\n");
57 return EFI_UNSUPPORTED;
58 }
59 return EFI_SUCCESS;
60 }
61
62 #ifdef CONFIG_ARM64_WORKAROUND_CLEAN_CACHE
63 #define DCTYPE "civac"
64 #else
65 #define DCTYPE "cvau"
66 #endif
67
efi_cache_sync_image(unsigned long image_base,unsigned long alloc_size,unsigned long code_size)68 void efi_cache_sync_image(unsigned long image_base,
69 unsigned long alloc_size,
70 unsigned long code_size)
71 {
72 u32 ctr = read_cpuid_effective_cachetype();
73 u64 lsize = 4 << cpuid_feature_extract_unsigned_field(ctr,
74 CTR_EL0_DminLine_SHIFT);
75
76 /* only perform the cache maintenance if needed for I/D coherency */
77 if (!(ctr & BIT(CTR_EL0_IDC_SHIFT))) {
78 do {
79 asm("dc " DCTYPE ", %0" :: "r"(image_base));
80 image_base += lsize;
81 code_size -= lsize;
82 } while (code_size >= lsize);
83 }
84
85 asm("ic ialluis");
86 dsb(ish);
87 isb();
88 }
89
primary_entry_offset(void)90 unsigned long __weak primary_entry_offset(void)
91 {
92 /*
93 * By default, we can invoke the kernel via the branch instruction in
94 * the image header, so offset #0. This will be overridden by the EFI
95 * stub build that is linked into the core kernel, as in that case, the
96 * image header may not have been loaded into memory, or may be mapped
97 * with non-executable permissions.
98 */
99 return 0;
100 }
101
efi_enter_kernel(unsigned long entrypoint,unsigned long fdt_addr,unsigned long fdt_size)102 void __noreturn efi_enter_kernel(unsigned long entrypoint,
103 unsigned long fdt_addr,
104 unsigned long fdt_size)
105 {
106 void (* __noreturn enter_kernel)(u64, u64, u64, u64);
107
108 enter_kernel = (void *)entrypoint + primary_entry_offset();
109 enter_kernel(fdt_addr, 0, 0, 0);
110 }
111