1 // SPDX-License-Identifier: GPL-2.0 !! 1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* 2 /*
3 * Author: Huacai Chen <chenhuacai@loongson.cn !! 3 * Copyright (C) 2014 Imagination Technologies
4 * Copyright (C) 2020-2022 Loongson Technology !! 4 * Author: Paul Burton <paul.burton@mips.com>
5 */ 5 */
6 6
7 #include <linux/binfmts.h> 7 #include <linux/binfmts.h>
8 #include <linux/elf.h> 8 #include <linux/elf.h>
9 #include <linux/export.h> 9 #include <linux/export.h>
10 #include <linux/sched.h> 10 #include <linux/sched.h>
11 11
12 #include <asm/cpu-features.h> 12 #include <asm/cpu-features.h>
13 #include <asm/cpu-info.h> 13 #include <asm/cpu-info.h>
14 14
>> 15 #ifdef CONFIG_MIPS_FP_SUPPORT
>> 16
>> 17 /* Whether to accept legacy-NaN and 2008-NaN user binaries. */
>> 18 bool mips_use_nan_legacy;
>> 19 bool mips_use_nan_2008;
>> 20
>> 21 /* FPU modes */
>> 22 enum {
>> 23 FP_FRE,
>> 24 FP_FR0,
>> 25 FP_FR1,
>> 26 };
>> 27
>> 28 /**
>> 29 * struct mode_req - ABI FPU mode requirements
>> 30 * @single: The program being loaded needs an FPU but it will only issue
>> 31 * single precision instructions meaning that it can execute in
>> 32 * either FR0 or FR1.
>> 33 * @soft: The soft(-float) requirement means that the program being
>> 34 * loaded needs has no FPU dependency at all (i.e. it has no
>> 35 * FPU instructions).
>> 36 * @fr1: The program being loaded depends on FPU being in FR=1 mode.
>> 37 * @frdefault: The program being loaded depends on the default FPU mode.
>> 38 * That is FR0 for O32 and FR1 for N32/N64.
>> 39 * @fre: The program being loaded depends on FPU with FRE=1. This mode is
>> 40 * a bridge which uses FR=1 whilst still being able to maintain
>> 41 * full compatibility with pre-existing code using the O32 FP32
>> 42 * ABI.
>> 43 *
>> 44 * More information about the FP ABIs can be found here:
>> 45 *
>> 46 * https://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking#10.4.1._Basic_mode_set-up
>> 47 *
>> 48 */
>> 49
>> 50 struct mode_req {
>> 51 bool single;
>> 52 bool soft;
>> 53 bool fr1;
>> 54 bool frdefault;
>> 55 bool fre;
>> 56 };
>> 57
>> 58 static const struct mode_req fpu_reqs[] = {
>> 59 [MIPS_ABI_FP_ANY] = { true, true, true, true, true },
>> 60 [MIPS_ABI_FP_DOUBLE] = { false, false, false, true, true },
>> 61 [MIPS_ABI_FP_SINGLE] = { true, false, false, false, false },
>> 62 [MIPS_ABI_FP_SOFT] = { false, true, false, false, false },
>> 63 [MIPS_ABI_FP_OLD_64] = { false, false, false, false, false },
>> 64 [MIPS_ABI_FP_XX] = { false, false, true, true, true },
>> 65 [MIPS_ABI_FP_64] = { false, false, true, false, false },
>> 66 [MIPS_ABI_FP_64A] = { false, false, true, false, true }
>> 67 };
>> 68
>> 69 /*
>> 70 * Mode requirements when .MIPS.abiflags is not present in the ELF.
>> 71 * Not present means that everything is acceptable except FR1.
>> 72 */
>> 73 static struct mode_req none_req = { true, true, false, true, true };
>> 74
15 int arch_elf_pt_proc(void *_ehdr, void *_phdr, 75 int arch_elf_pt_proc(void *_ehdr, void *_phdr, struct file *elf,
16 bool is_interp, struct ar 76 bool is_interp, struct arch_elf_state *state)
17 { 77 {
>> 78 union {
>> 79 struct elf32_hdr e32;
>> 80 struct elf64_hdr e64;
>> 81 } *ehdr = _ehdr;
>> 82 struct elf32_phdr *phdr32 = _phdr;
>> 83 struct elf64_phdr *phdr64 = _phdr;
>> 84 struct mips_elf_abiflags_v0 abiflags;
>> 85 bool elf32;
>> 86 u32 flags;
>> 87 int ret;
>> 88 loff_t pos;
>> 89
>> 90 elf32 = ehdr->e32.e_ident[EI_CLASS] == ELFCLASS32;
>> 91 flags = elf32 ? ehdr->e32.e_flags : ehdr->e64.e_flags;
>> 92
>> 93 /* Let's see if this is an O32 ELF */
>> 94 if (elf32) {
>> 95 if (flags & EF_MIPS_FP64) {
>> 96 /*
>> 97 * Set MIPS_ABI_FP_OLD_64 for EF_MIPS_FP64. We will override it
>> 98 * later if needed
>> 99 */
>> 100 if (is_interp)
>> 101 state->interp_fp_abi = MIPS_ABI_FP_OLD_64;
>> 102 else
>> 103 state->fp_abi = MIPS_ABI_FP_OLD_64;
>> 104 }
>> 105 if (phdr32->p_type != PT_MIPS_ABIFLAGS)
>> 106 return 0;
>> 107
>> 108 if (phdr32->p_filesz < sizeof(abiflags))
>> 109 return -EINVAL;
>> 110 pos = phdr32->p_offset;
>> 111 } else {
>> 112 if (phdr64->p_type != PT_MIPS_ABIFLAGS)
>> 113 return 0;
>> 114 if (phdr64->p_filesz < sizeof(abiflags))
>> 115 return -EINVAL;
>> 116 pos = phdr64->p_offset;
>> 117 }
>> 118
>> 119 ret = kernel_read(elf, &abiflags, sizeof(abiflags), &pos);
>> 120 if (ret < 0)
>> 121 return ret;
>> 122 if (ret != sizeof(abiflags))
>> 123 return -EIO;
>> 124
>> 125 /* Record the required FP ABIs for use by mips_check_elf */
>> 126 if (is_interp)
>> 127 state->interp_fp_abi = abiflags.fp_abi;
>> 128 else
>> 129 state->fp_abi = abiflags.fp_abi;
>> 130
18 return 0; 131 return 0;
19 } 132 }
20 133
21 int arch_check_elf(void *_ehdr, bool has_inter 134 int arch_check_elf(void *_ehdr, bool has_interpreter, void *_interp_ehdr,
22 struct arch_elf_state *stat 135 struct arch_elf_state *state)
23 { 136 {
>> 137 union {
>> 138 struct elf32_hdr e32;
>> 139 struct elf64_hdr e64;
>> 140 } *ehdr = _ehdr;
>> 141 union {
>> 142 struct elf32_hdr e32;
>> 143 struct elf64_hdr e64;
>> 144 } *iehdr = _interp_ehdr;
>> 145 struct mode_req prog_req, interp_req;
>> 146 int fp_abi, interp_fp_abi, abi0, abi1, max_abi;
>> 147 bool elf32;
>> 148 u32 flags;
>> 149
>> 150 elf32 = ehdr->e32.e_ident[EI_CLASS] == ELFCLASS32;
>> 151 flags = elf32 ? ehdr->e32.e_flags : ehdr->e64.e_flags;
>> 152
>> 153 /*
>> 154 * Determine the NaN personality, reject the binary if not allowed.
>> 155 * Also ensure that any interpreter matches the executable.
>> 156 */
>> 157 if (flags & EF_MIPS_NAN2008) {
>> 158 if (mips_use_nan_2008)
>> 159 state->nan_2008 = 1;
>> 160 else
>> 161 return -ENOEXEC;
>> 162 } else {
>> 163 if (mips_use_nan_legacy)
>> 164 state->nan_2008 = 0;
>> 165 else
>> 166 return -ENOEXEC;
>> 167 }
>> 168 if (has_interpreter) {
>> 169 bool ielf32;
>> 170 u32 iflags;
>> 171
>> 172 ielf32 = iehdr->e32.e_ident[EI_CLASS] == ELFCLASS32;
>> 173 iflags = ielf32 ? iehdr->e32.e_flags : iehdr->e64.e_flags;
>> 174
>> 175 if ((flags ^ iflags) & EF_MIPS_NAN2008)
>> 176 return -ELIBBAD;
>> 177 }
>> 178
>> 179 if (!IS_ENABLED(CONFIG_MIPS_O32_FP64_SUPPORT))
>> 180 return 0;
>> 181
>> 182 fp_abi = state->fp_abi;
>> 183
>> 184 if (has_interpreter) {
>> 185 interp_fp_abi = state->interp_fp_abi;
>> 186
>> 187 abi0 = min(fp_abi, interp_fp_abi);
>> 188 abi1 = max(fp_abi, interp_fp_abi);
>> 189 } else {
>> 190 abi0 = abi1 = fp_abi;
>> 191 }
>> 192
>> 193 if (elf32 && !(flags & EF_MIPS_ABI2)) {
>> 194 /* Default to a mode capable of running code expecting FR=0 */
>> 195 state->overall_fp_mode = cpu_has_mips_r6 ? FP_FRE : FP_FR0;
>> 196
>> 197 /* Allow all ABIs we know about */
>> 198 max_abi = MIPS_ABI_FP_64A;
>> 199 } else {
>> 200 /* MIPS64 code always uses FR=1, thus the default is easy */
>> 201 state->overall_fp_mode = FP_FR1;
>> 202
>> 203 /* Disallow access to the various FPXX & FP64 ABIs */
>> 204 max_abi = MIPS_ABI_FP_SOFT;
>> 205 }
>> 206
>> 207 if ((abi0 > max_abi && abi0 != MIPS_ABI_FP_UNKNOWN) ||
>> 208 (abi1 > max_abi && abi1 != MIPS_ABI_FP_UNKNOWN))
>> 209 return -ELIBBAD;
>> 210
>> 211 /* It's time to determine the FPU mode requirements */
>> 212 prog_req = (abi0 == MIPS_ABI_FP_UNKNOWN) ? none_req : fpu_reqs[abi0];
>> 213 interp_req = (abi1 == MIPS_ABI_FP_UNKNOWN) ? none_req : fpu_reqs[abi1];
>> 214
>> 215 /*
>> 216 * Check whether the program's and interp's ABIs have a matching FPU
>> 217 * mode requirement.
>> 218 */
>> 219 prog_req.single = interp_req.single && prog_req.single;
>> 220 prog_req.soft = interp_req.soft && prog_req.soft;
>> 221 prog_req.fr1 = interp_req.fr1 && prog_req.fr1;
>> 222 prog_req.frdefault = interp_req.frdefault && prog_req.frdefault;
>> 223 prog_req.fre = interp_req.fre && prog_req.fre;
>> 224
>> 225 /*
>> 226 * Determine the desired FPU mode
>> 227 *
>> 228 * Decision making:
>> 229 *
>> 230 * - We want FR_FRE if FRE=1 and both FR=1 and FR=0 are false. This
>> 231 * means that we have a combination of program and interpreter
>> 232 * that inherently require the hybrid FP mode.
>> 233 * - If FR1 and FRDEFAULT is true, that means we hit the any-abi or
>> 234 * fpxx case. This is because, in any-ABI (or no-ABI) we have no FPU
>> 235 * instructions so we don't care about the mode. We will simply use
>> 236 * the one preferred by the hardware. In fpxx case, that ABI can
>> 237 * handle both FR=1 and FR=0, so, again, we simply choose the one
>> 238 * preferred by the hardware. Next, if we only use single-precision
>> 239 * FPU instructions, and the default ABI FPU mode is not good
>> 240 * (ie single + any ABI combination), we set again the FPU mode to the
>> 241 * one is preferred by the hardware. Next, if we know that the code
>> 242 * will only use single-precision instructions, shown by single being
>> 243 * true but frdefault being false, then we again set the FPU mode to
>> 244 * the one that is preferred by the hardware.
>> 245 * - We want FP_FR1 if that's the only matching mode and the default one
>> 246 * is not good.
>> 247 * - Return with -ELIBADD if we can't find a matching FPU mode.
>> 248 */
>> 249 if (prog_req.fre && !prog_req.frdefault && !prog_req.fr1)
>> 250 state->overall_fp_mode = FP_FRE;
>> 251 else if ((prog_req.fr1 && prog_req.frdefault) ||
>> 252 (prog_req.single && !prog_req.frdefault))
>> 253 /* Make sure 64-bit MIPS III/IV/64R1 will not pick FR1 */
>> 254 state->overall_fp_mode = ((raw_current_cpu_data.fpu_id & MIPS_FPIR_F64) &&
>> 255 cpu_has_mips_r2_r6) ?
>> 256 FP_FR1 : FP_FR0;
>> 257 else if (prog_req.fr1)
>> 258 state->overall_fp_mode = FP_FR1;
>> 259 else if (!prog_req.fre && !prog_req.frdefault &&
>> 260 !prog_req.fr1 && !prog_req.single && !prog_req.soft)
>> 261 return -ELIBBAD;
>> 262
24 return 0; 263 return 0;
25 } 264 }
>> 265
>> 266 static inline void set_thread_fp_mode(int hybrid, int regs32)
>> 267 {
>> 268 if (hybrid)
>> 269 set_thread_flag(TIF_HYBRID_FPREGS);
>> 270 else
>> 271 clear_thread_flag(TIF_HYBRID_FPREGS);
>> 272 if (regs32)
>> 273 set_thread_flag(TIF_32BIT_FPREGS);
>> 274 else
>> 275 clear_thread_flag(TIF_32BIT_FPREGS);
>> 276 }
>> 277
>> 278 void mips_set_personality_fp(struct arch_elf_state *state)
>> 279 {
>> 280 /*
>> 281 * This function is only ever called for O32 ELFs so we should
>> 282 * not be worried about N32/N64 binaries.
>> 283 */
>> 284
>> 285 if (!IS_ENABLED(CONFIG_MIPS_O32_FP64_SUPPORT))
>> 286 return;
>> 287
>> 288 switch (state->overall_fp_mode) {
>> 289 case FP_FRE:
>> 290 set_thread_fp_mode(1, 0);
>> 291 break;
>> 292 case FP_FR0:
>> 293 set_thread_fp_mode(0, 1);
>> 294 break;
>> 295 case FP_FR1:
>> 296 set_thread_fp_mode(0, 0);
>> 297 break;
>> 298 default:
>> 299 BUG();
>> 300 }
>> 301 }
>> 302
>> 303 /*
>> 304 * Select the IEEE 754 NaN encoding and ABS.fmt/NEG.fmt execution mode
>> 305 * in FCSR according to the ELF NaN personality.
>> 306 */
>> 307 void mips_set_personality_nan(struct arch_elf_state *state)
>> 308 {
>> 309 struct cpuinfo_mips *c = &boot_cpu_data;
>> 310 struct task_struct *t = current;
>> 311
>> 312 t->thread.fpu.fcr31 = c->fpu_csr31;
>> 313 switch (state->nan_2008) {
>> 314 case 0:
>> 315 break;
>> 316 case 1:
>> 317 if (!(c->fpu_msk31 & FPU_CSR_NAN2008))
>> 318 t->thread.fpu.fcr31 |= FPU_CSR_NAN2008;
>> 319 if (!(c->fpu_msk31 & FPU_CSR_ABS2008))
>> 320 t->thread.fpu.fcr31 |= FPU_CSR_ABS2008;
>> 321 break;
>> 322 default:
>> 323 BUG();
>> 324 }
>> 325 }
>> 326
>> 327 #endif /* CONFIG_MIPS_FP_SUPPORT */
>> 328
>> 329 int mips_elf_read_implies_exec(void *elf_ex, int exstack)
>> 330 {
>> 331 /*
>> 332 * Set READ_IMPLIES_EXEC only on non-NX systems that
>> 333 * do not request a specific state via PT_GNU_STACK.
>> 334 */
>> 335 return (!cpu_has_rixi && exstack == EXSTACK_DEFAULT);
>> 336 }
>> 337 EXPORT_SYMBOL(mips_elf_read_implies_exec);
26 338
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