1 /*
2 * Copyright (c) 2000-2020 Apple Inc. All rights reserved.
3 */
4 /*
5 * Copyright (C) 1990, NeXT, Inc.
6 *
7 * File: next/kern_machdep.c
8 * Author: John Seamons
9 *
10 * Machine-specific kernel routines.
11 */
12
13 #include <sys/types.h>
14 #include <mach/machine.h>
15 #include <kern/cpu_number.h>
16 #include <libkern/libkern.h>
17 #include <machine/exec.h>
18 #include <pexpert/arm64/board_config.h>
19
20 #if __arm64__
21 static cpu_subtype_t cpu_subtype32(void);
22 #endif /* __arm64__ */
23
24 #if __arm64__
25 /*
26 * When an arm64 CPU is executing an arm32 binary, we need to map from the
27 * host's 64-bit subtype to the appropriate 32-bit subtype.
28 */
29 static cpu_subtype_t
cpu_subtype32()30 cpu_subtype32()
31 {
32 switch (cpu_subtype()) {
33 case CPU_SUBTYPE_ARM64_V8:
34 return CPU_SUBTYPE_ARM_V8;
35 default:
36 return 0;
37 }
38 }
39
40 static int
grade_arm64e_binary(cpu_subtype_t execfeatures)41 grade_arm64e_binary(cpu_subtype_t execfeatures)
42 {
43 #if XNU_TARGET_OS_IOS
44 /*
45 * iOS 13 toolchains produced unversioned arm64e slices which are not
46 * ABI compatible with this release.
47 */
48 if ((execfeatures & CPU_SUBTYPE_PTRAUTH_ABI) == 0) {
49 #if DEBUG || DEVELOPMENT
50 printf("%s: arm64e prerelease ABI cannot be used with this kernel\n", __func__);
51 #endif /* DEBUG || DEVELOPMENT */
52 return 0;
53 }
54 #endif /* XNU_TARGET_OS_IOS */
55
56 /* The current ABI version is preferred over arm64 */
57 if (CPU_SUBTYPE_ARM64_PTR_AUTH_VERSION(execfeatures) ==
58 CPU_SUBTYPE_ARM64_PTR_AUTH_CURRENT_VERSION) {
59 return 12;
60 }
61
62 /* Future ABIs are allowed, but exec_mach_imgact will treat it like an arm64 slice */
63 return 11;
64 }
65 #endif /* __arm64__ */
66
67 /**********************************************************************
68 * Routine: grade_binary()
69 *
70 * Function: Return a relative preference for exectypes and
71 * execsubtypes in fat executable files. The higher the
72 * grade, the higher the preference. A grade of 0 means
73 * not acceptable.
74 **********************************************************************/
75 int
grade_binary(cpu_type_t exectype,cpu_subtype_t execsubtype,cpu_subtype_t execfeatures __unused,bool allow_simulator_binary __unused)76 grade_binary(cpu_type_t exectype, cpu_subtype_t execsubtype, cpu_subtype_t execfeatures __unused, bool allow_simulator_binary __unused)
77 {
78 #if __arm64__
79 cpu_subtype_t hostsubtype =
80 (exectype & CPU_ARCH_ABI64) ? cpu_subtype() : cpu_subtype32();
81 #else
82 cpu_subtype_t hostsubtype = cpu_subtype();
83 #endif /* __arm64__ */
84
85 switch (exectype) {
86 #if __arm64__
87 case CPU_TYPE_ARM64:
88 switch (hostsubtype) {
89 case CPU_SUBTYPE_ARM64_V8:
90 switch (execsubtype) {
91 case CPU_SUBTYPE_ARM64_V8:
92 return 10;
93 case CPU_SUBTYPE_ARM64_ALL:
94 return 9;
95 }
96 break;
97
98 case CPU_SUBTYPE_ARM64E:
99 switch (execsubtype) {
100 case CPU_SUBTYPE_ARM64E:
101 return grade_arm64e_binary(execfeatures);
102 case CPU_SUBTYPE_ARM64_V8:
103 return 10;
104 case CPU_SUBTYPE_ARM64_ALL:
105 return 9;
106 }
107 } /* switch (hostsubtype) */
108 break;
109
110 #else /* __arm64__ */
111
112 case CPU_TYPE_ARM:
113 switch (hostsubtype) {
114 /*
115 * For 32-bit ARMv8, try the ARMv8 slice before falling back to Swift.
116 */
117 case CPU_SUBTYPE_ARM_V8:
118 switch (execsubtype) {
119 case CPU_SUBTYPE_ARM_V8:
120 return 7;
121 }
122 goto v7s;
123
124 /*
125 * For Swift and later, we prefer to run a swift slice, but fall back
126 * to v7 as Cortex A9 errata should not apply
127 */
128 v7s:
129 case CPU_SUBTYPE_ARM_V7S:
130 switch (execsubtype) {
131 case CPU_SUBTYPE_ARM_V7S:
132 return 6;
133 }
134 goto v7;
135
136 /*
137 * For Cortex A7, accept v7k only due to differing ABI
138 */
139 case CPU_SUBTYPE_ARM_V7K:
140 switch (execsubtype) {
141 case CPU_SUBTYPE_ARM_V7K:
142 return 6;
143 }
144 break;
145
146 /*
147 * For Cortex A9, we prefer the A9 slice, but will run v7 albeit
148 * under the risk of hitting the NEON load/store errata
149 */
150 case CPU_SUBTYPE_ARM_V7F:
151 switch (execsubtype) {
152 case CPU_SUBTYPE_ARM_V7F:
153 return 6;
154 }
155 goto v7;
156
157 v7:
158 case CPU_SUBTYPE_ARM_V7:
159 switch (execsubtype) {
160 case CPU_SUBTYPE_ARM_V7:
161 return 5;
162 }
163 // fall through...
164
165 case CPU_SUBTYPE_ARM_V6:
166 switch (execsubtype) {
167 case CPU_SUBTYPE_ARM_V6:
168 return 4;
169 }
170 // fall through...
171
172 case CPU_SUBTYPE_ARM_V5TEJ:
173 switch (execsubtype) {
174 case CPU_SUBTYPE_ARM_V5TEJ:
175 return 3;
176 }
177 // fall through
178
179 case CPU_SUBTYPE_ARM_V4T:
180 switch (execsubtype) {
181 case CPU_SUBTYPE_ARM_V4T:
182 return 2;
183 case CPU_SUBTYPE_ARM_ALL:
184 return 1;
185 }
186 break;
187
188 case CPU_SUBTYPE_ARM_XSCALE:
189 switch (execsubtype) {
190 case CPU_SUBTYPE_ARM_XSCALE:
191 return 4;
192 case CPU_SUBTYPE_ARM_V5TEJ:
193 return 3;
194 case CPU_SUBTYPE_ARM_V4T:
195 return 2;
196 case CPU_SUBTYPE_ARM_ALL:
197 return 1;
198 }
199 break;
200 }
201 #endif /* __arm64__ */
202 }
203
204 return 0;
205 }
206