1 // SPDX-License-Identifier: GPL-2.0 1 // SPDX-License-Identifier: GPL-2.0
2 2
3 //! The custom target specification file gener 3 //! The custom target specification file generator for `rustc`.
4 //! 4 //!
5 //! To configure a target from scratch, a JSON 5 //! To configure a target from scratch, a JSON-encoded file has to be passed
6 //! to `rustc` (introduced in [RFC 131]). Thes 6 //! to `rustc` (introduced in [RFC 131]). These options and the file itself are
7 //! unstable. Eventually, `rustc` should provi 7 //! unstable. Eventually, `rustc` should provide a way to do this in a stable
8 //! manner. For instance, via command-line arg 8 //! manner. For instance, via command-line arguments. Therefore, this file
9 //! should avoid using keys which can be set v 9 //! should avoid using keys which can be set via `-C` or `-Z` options.
10 //! 10 //!
11 //! [RFC 131]: https://rust-lang.github.io/rfc 11 //! [RFC 131]: https://rust-lang.github.io/rfcs/0131-target-specification.html
12 12
13 use std::{ 13 use std::{
14 collections::HashMap, 14 collections::HashMap,
15 fmt::{Display, Formatter, Result}, 15 fmt::{Display, Formatter, Result},
16 io::BufRead, 16 io::BufRead,
17 }; 17 };
18 18
19 enum Value { 19 enum Value {
20 Boolean(bool), 20 Boolean(bool),
21 Number(i32), 21 Number(i32),
22 String(String), 22 String(String),
23 Array(Vec<Value>), 23 Array(Vec<Value>),
24 Object(Object), 24 Object(Object),
25 } 25 }
26 26
27 type Object = Vec<(String, Value)>; 27 type Object = Vec<(String, Value)>;
28 28
29 fn comma_sep<T>( 29 fn comma_sep<T>(
30 seq: &[T], 30 seq: &[T],
31 formatter: &mut Formatter<'_>, 31 formatter: &mut Formatter<'_>,
32 f: impl Fn(&mut Formatter<'_>, &T) -> Resu 32 f: impl Fn(&mut Formatter<'_>, &T) -> Result,
33 ) -> Result { 33 ) -> Result {
34 if let [ref rest @ .., ref last] = seq[..] 34 if let [ref rest @ .., ref last] = seq[..] {
35 for v in rest { 35 for v in rest {
36 f(formatter, v)?; 36 f(formatter, v)?;
37 formatter.write_str(",")?; 37 formatter.write_str(",")?;
38 } 38 }
39 f(formatter, last)?; 39 f(formatter, last)?;
40 } 40 }
41 Ok(()) 41 Ok(())
42 } 42 }
43 43
44 /// Minimal "almost JSON" generator (e.g. no ` 44 /// Minimal "almost JSON" generator (e.g. no `null`s, no escaping),
45 /// enough for this purpose. 45 /// enough for this purpose.
46 impl Display for Value { 46 impl Display for Value {
47 fn fmt(&self, formatter: &mut Formatter<'_ 47 fn fmt(&self, formatter: &mut Formatter<'_>) -> Result {
48 match self { 48 match self {
49 Value::Boolean(boolean) => write!( 49 Value::Boolean(boolean) => write!(formatter, "{}", boolean),
50 Value::Number(number) => write!(fo 50 Value::Number(number) => write!(formatter, "{}", number),
51 Value::String(string) => write!(fo 51 Value::String(string) => write!(formatter, "\"{}\"", string),
52 Value::Array(values) => { 52 Value::Array(values) => {
53 formatter.write_str("[")?; 53 formatter.write_str("[")?;
54 comma_sep(&values[..], formatt 54 comma_sep(&values[..], formatter, |formatter, v| v.fmt(formatter))?;
55 formatter.write_str("]") 55 formatter.write_str("]")
56 } 56 }
57 Value::Object(object) => { 57 Value::Object(object) => {
58 formatter.write_str("{")?; 58 formatter.write_str("{")?;
59 comma_sep(&object[..], formatt 59 comma_sep(&object[..], formatter, |formatter, v| {
60 write!(formatter, "\"{}\": 60 write!(formatter, "\"{}\": {}", v.0, v.1)
61 })?; 61 })?;
62 formatter.write_str("}") 62 formatter.write_str("}")
63 } 63 }
64 } 64 }
65 } 65 }
66 } 66 }
67 67
68 impl From<bool> for Value { 68 impl From<bool> for Value {
69 fn from(value: bool) -> Self { 69 fn from(value: bool) -> Self {
70 Self::Boolean(value) 70 Self::Boolean(value)
71 } 71 }
72 } 72 }
73 73
74 impl From<i32> for Value { 74 impl From<i32> for Value {
75 fn from(value: i32) -> Self { 75 fn from(value: i32) -> Self {
76 Self::Number(value) 76 Self::Number(value)
77 } 77 }
78 } 78 }
79 79
80 impl From<String> for Value { 80 impl From<String> for Value {
81 fn from(value: String) -> Self { 81 fn from(value: String) -> Self {
82 Self::String(value) 82 Self::String(value)
83 } 83 }
84 } 84 }
85 85
86 impl From<&str> for Value { 86 impl From<&str> for Value {
87 fn from(value: &str) -> Self { 87 fn from(value: &str) -> Self {
88 Self::String(value.to_string()) 88 Self::String(value.to_string())
89 } 89 }
90 } 90 }
91 91
92 impl From<Object> for Value { 92 impl From<Object> for Value {
93 fn from(object: Object) -> Self { 93 fn from(object: Object) -> Self {
94 Self::Object(object) 94 Self::Object(object)
95 } 95 }
96 } 96 }
97 97
98 impl<T: Into<Value>, const N: usize> From<[T; 98 impl<T: Into<Value>, const N: usize> From<[T; N]> for Value {
99 fn from(i: [T; N]) -> Self { 99 fn from(i: [T; N]) -> Self {
100 Self::Array(i.into_iter().map(|v| v.in 100 Self::Array(i.into_iter().map(|v| v.into()).collect())
101 } 101 }
102 } 102 }
103 103
104 struct TargetSpec(Object); 104 struct TargetSpec(Object);
105 105
106 impl TargetSpec { 106 impl TargetSpec {
107 fn new() -> TargetSpec { 107 fn new() -> TargetSpec {
108 TargetSpec(Vec::new()) 108 TargetSpec(Vec::new())
109 } 109 }
110 110
111 fn push(&mut self, key: &str, value: impl 111 fn push(&mut self, key: &str, value: impl Into<Value>) {
112 self.0.push((key.to_string(), value.in 112 self.0.push((key.to_string(), value.into()));
113 } 113 }
114 } 114 }
115 115
116 impl Display for TargetSpec { 116 impl Display for TargetSpec {
117 fn fmt(&self, formatter: &mut Formatter<'_ 117 fn fmt(&self, formatter: &mut Formatter<'_>) -> Result {
118 // We add some newlines for clarity. 118 // We add some newlines for clarity.
119 formatter.write_str("{\n")?; 119 formatter.write_str("{\n")?;
120 if let [ref rest @ .., ref last] = sel 120 if let [ref rest @ .., ref last] = self.0[..] {
121 for (key, value) in rest { 121 for (key, value) in rest {
122 write!(formatter, " \"{}\": 122 write!(formatter, " \"{}\": {},\n", key, value)?;
123 } 123 }
124 write!(formatter, " \"{}\": {}\ 124 write!(formatter, " \"{}\": {}\n", last.0, last.1)?;
125 } 125 }
126 formatter.write_str("}") 126 formatter.write_str("}")
127 } 127 }
128 } 128 }
129 129
130 struct KernelConfig(HashMap<String, String>); 130 struct KernelConfig(HashMap<String, String>);
131 131
132 impl KernelConfig { 132 impl KernelConfig {
133 /// Parses `include/config/auto.conf` from 133 /// Parses `include/config/auto.conf` from `stdin`.
134 fn from_stdin() -> KernelConfig { 134 fn from_stdin() -> KernelConfig {
135 let mut result = HashMap::new(); 135 let mut result = HashMap::new();
136 136
137 let stdin = std::io::stdin(); 137 let stdin = std::io::stdin();
138 let mut handle = stdin.lock(); 138 let mut handle = stdin.lock();
139 let mut line = String::new(); 139 let mut line = String::new();
140 140
141 loop { 141 loop {
142 line.clear(); 142 line.clear();
143 143
144 if handle.read_line(&mut line).unw 144 if handle.read_line(&mut line).unwrap() == 0 {
145 break; 145 break;
146 } 146 }
147 147
148 if line.starts_with('#') { 148 if line.starts_with('#') {
149 continue; 149 continue;
150 } 150 }
151 151
152 let (key, value) = line.split_once 152 let (key, value) = line.split_once('=').expect("Missing `=` in line.");
153 result.insert(key.to_string(), val 153 result.insert(key.to_string(), value.trim_end_matches('\n').to_string());
154 } 154 }
155 155
156 KernelConfig(result) 156 KernelConfig(result)
157 } 157 }
158 158
159 /// Does the option exist in the configura 159 /// Does the option exist in the configuration (any value)?
160 /// 160 ///
161 /// The argument must be passed without th 161 /// The argument must be passed without the `CONFIG_` prefix.
162 /// This avoids repetition and it also avo 162 /// This avoids repetition and it also avoids `fixdep` making us
163 /// depend on it. 163 /// depend on it.
164 fn has(&self, option: &str) -> bool { 164 fn has(&self, option: &str) -> bool {
165 let option = "CONFIG_".to_owned() + op 165 let option = "CONFIG_".to_owned() + option;
166 self.0.contains_key(&option) 166 self.0.contains_key(&option)
167 } 167 }
168 } 168 }
169 169
170 fn main() { 170 fn main() {
171 let cfg = KernelConfig::from_stdin(); 171 let cfg = KernelConfig::from_stdin();
172 let mut ts = TargetSpec::new(); 172 let mut ts = TargetSpec::new();
173 173
174 // `llvm-target`s are taken from `scripts/ 174 // `llvm-target`s are taken from `scripts/Makefile.clang`.
175 if cfg.has("ARM64") { 175 if cfg.has("ARM64") {
176 panic!("arm64 uses the builtin rustc a 176 panic!("arm64 uses the builtin rustc aarch64-unknown-none target");
177 } else if cfg.has("RISCV") { 177 } else if cfg.has("RISCV") {
178 if cfg.has("64BIT") { 178 if cfg.has("64BIT") {
179 panic!("64-bit RISC-V uses the bui 179 panic!("64-bit RISC-V uses the builtin rustc riscv64-unknown-none-elf target");
180 } else { 180 } else {
181 panic!("32-bit RISC-V is an unsupp 181 panic!("32-bit RISC-V is an unsupported architecture");
182 } 182 }
183 } else if cfg.has("X86_64") { 183 } else if cfg.has("X86_64") {
184 ts.push("arch", "x86_64"); 184 ts.push("arch", "x86_64");
185 ts.push( 185 ts.push(
186 "data-layout", 186 "data-layout",
187 "e-m:e-p270:32:32-p271:32:32-p272: 187 "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128",
188 ); 188 );
189 let mut features = "-mmx,+soft-float". 189 let mut features = "-mmx,+soft-float".to_string();
190 if cfg.has("MITIGATION_RETPOLINE") { 190 if cfg.has("MITIGATION_RETPOLINE") {
191 // The kernel uses `-mretpoline-ex 191 // The kernel uses `-mretpoline-external-thunk` (for Clang), which Clang maps to the
192 // target feature of the same name 192 // target feature of the same name plus the other two target features in
193 // `clang/lib/Driver/ToolChains/Ar 193 // `clang/lib/Driver/ToolChains/Arch/X86.cpp`. These should be eventually enabled via
194 // `-Ctarget-feature` when `rustc` 194 // `-Ctarget-feature` when `rustc` starts recognizing them (or via a new dedicated
195 // flag); see https://github.com/r 195 // flag); see https://github.com/rust-lang/rust/issues/116852.
196 features += ",+retpoline-external- 196 features += ",+retpoline-external-thunk";
197 features += ",+retpoline-indirect- 197 features += ",+retpoline-indirect-branches";
198 features += ",+retpoline-indirect- 198 features += ",+retpoline-indirect-calls";
199 } 199 }
200 if cfg.has("MITIGATION_SLS") { 200 if cfg.has("MITIGATION_SLS") {
201 // The kernel uses `-mharden-sls=a 201 // The kernel uses `-mharden-sls=all`, which Clang maps to both these target features in
202 // `clang/lib/Driver/ToolChains/Ar 202 // `clang/lib/Driver/ToolChains/Arch/X86.cpp`. These should be eventually enabled via
203 // `-Ctarget-feature` when `rustc` 203 // `-Ctarget-feature` when `rustc` starts recognizing them (or via a new dedicated
204 // flag); see https://github.com/r 204 // flag); see https://github.com/rust-lang/rust/issues/116851.
205 features += ",+harden-sls-ijmp"; 205 features += ",+harden-sls-ijmp";
206 features += ",+harden-sls-ret"; 206 features += ",+harden-sls-ret";
207 } 207 }
208 ts.push("features", features); 208 ts.push("features", features);
209 ts.push("llvm-target", "x86_64-linux-g 209 ts.push("llvm-target", "x86_64-linux-gnu");
210 ts.push("supported-sanitizers", ["kcfi 210 ts.push("supported-sanitizers", ["kcfi", "kernel-address"]);
211 ts.push("target-pointer-width", "64"); 211 ts.push("target-pointer-width", "64");
212 } else if cfg.has("X86_32") { 212 } else if cfg.has("X86_32") {
213 // This only works on UML, as i386 oth 213 // This only works on UML, as i386 otherwise needs regparm support in rustc
214 if !cfg.has("UML") { 214 if !cfg.has("UML") {
215 panic!("32-bit x86 only works unde 215 panic!("32-bit x86 only works under UML");
216 } 216 }
217 ts.push("arch", "x86"); 217 ts.push("arch", "x86");
218 ts.push( 218 ts.push(
219 "data-layout", 219 "data-layout",
220 "e-m:e-p:32:32-p270:32:32-p271:32: 220 "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-i128:128-f64:32:64-f80:32-n8:16:32-S128",
221 ); 221 );
222 let mut features = "-mmx,+soft-float". 222 let mut features = "-mmx,+soft-float".to_string();
223 if cfg.has("MITIGATION_RETPOLINE") { 223 if cfg.has("MITIGATION_RETPOLINE") {
224 features += ",+retpoline-external- 224 features += ",+retpoline-external-thunk";
225 } 225 }
226 ts.push("features", features); 226 ts.push("features", features);
227 ts.push("llvm-target", "i386-unknown-l 227 ts.push("llvm-target", "i386-unknown-linux-gnu");
228 ts.push("target-pointer-width", "32"); 228 ts.push("target-pointer-width", "32");
229 } else if cfg.has("LOONGARCH") { 229 } else if cfg.has("LOONGARCH") {
230 panic!("loongarch uses the builtin rus 230 panic!("loongarch uses the builtin rustc loongarch64-unknown-none-softfloat target");
231 } else { 231 } else {
232 panic!("Unsupported architecture"); 232 panic!("Unsupported architecture");
233 } 233 }
234 234
235 ts.push("emit-debug-gdb-scripts", false); 235 ts.push("emit-debug-gdb-scripts", false);
236 ts.push("frame-pointer", "may-omit"); 236 ts.push("frame-pointer", "may-omit");
237 ts.push( 237 ts.push(
238 "stack-probes", 238 "stack-probes",
239 vec![("kind".to_string(), Value::Strin 239 vec![("kind".to_string(), Value::String("none".to_string()))],
240 ); 240 );
241 241
242 // Everything else is LE, whether `CPU_LIT 242 // Everything else is LE, whether `CPU_LITTLE_ENDIAN` is declared or not
243 // (e.g. x86). It is also `rustc`'s defaul 243 // (e.g. x86). It is also `rustc`'s default.
244 if cfg.has("CPU_BIG_ENDIAN") { 244 if cfg.has("CPU_BIG_ENDIAN") {
245 ts.push("target-endian", "big"); 245 ts.push("target-endian", "big");
246 } 246 }
247 247
248 println!("{}", ts); 248 println!("{}", ts);
249 } 249 }
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