Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2014 Imagination Technologies |
| 3 | * Author: Paul Burton <paul.burton@imgtec.com> |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License as published by the |
| 7 | * Free Software Foundation; either version 2 of the License, or (at your |
| 8 | * option) any later version. |
| 9 | */ |
| 10 | |
| 11 | #include <linux/elf.h> |
| 12 | #include <linux/sched.h> |
| 13 | |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 14 | /* FPU modes */ |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 15 | enum { |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 16 | FP_FRE, |
| 17 | FP_FR0, |
| 18 | FP_FR1, |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 19 | }; |
| 20 | |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 21 | /** |
| 22 | * struct mode_req - ABI FPU mode requirements |
| 23 | * @single: The program being loaded needs an FPU but it will only issue |
| 24 | * single precision instructions meaning that it can execute in |
| 25 | * either FR0 or FR1. |
| 26 | * @soft: The soft(-float) requirement means that the program being |
| 27 | * loaded needs has no FPU dependency at all (i.e. it has no |
| 28 | * FPU instructions). |
| 29 | * @fr1: The program being loaded depends on FPU being in FR=1 mode. |
| 30 | * @frdefault: The program being loaded depends on the default FPU mode. |
| 31 | * That is FR0 for O32 and FR1 for N32/N64. |
| 32 | * @fre: The program being loaded depends on FPU with FRE=1. This mode is |
| 33 | * a bridge which uses FR=1 whilst still being able to maintain |
| 34 | * full compatibility with pre-existing code using the O32 FP32 |
| 35 | * ABI. |
| 36 | * |
| 37 | * More information about the FP ABIs can be found here: |
| 38 | * |
| 39 | * https://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking#10.4.1._Basic_mode_set-up |
| 40 | * |
| 41 | */ |
| 42 | |
| 43 | struct mode_req { |
| 44 | bool single; |
| 45 | bool soft; |
| 46 | bool fr1; |
| 47 | bool frdefault; |
| 48 | bool fre; |
| 49 | }; |
| 50 | |
| 51 | static const struct mode_req fpu_reqs[] = { |
| 52 | [MIPS_ABI_FP_ANY] = { true, true, true, true, true }, |
| 53 | [MIPS_ABI_FP_DOUBLE] = { false, false, false, true, true }, |
| 54 | [MIPS_ABI_FP_SINGLE] = { true, false, false, false, false }, |
| 55 | [MIPS_ABI_FP_SOFT] = { false, true, false, false, false }, |
| 56 | [MIPS_ABI_FP_OLD_64] = { false, false, false, false, false }, |
| 57 | [MIPS_ABI_FP_XX] = { false, false, true, true, true }, |
| 58 | [MIPS_ABI_FP_64] = { false, false, true, false, false }, |
| 59 | [MIPS_ABI_FP_64A] = { false, false, true, false, true } |
| 60 | }; |
| 61 | |
| 62 | /* |
| 63 | * Mode requirements when .MIPS.abiflags is not present in the ELF. |
| 64 | * Not present means that everything is acceptable except FR1. |
| 65 | */ |
| 66 | static struct mode_req none_req = { true, true, false, true, true }; |
| 67 | |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 68 | int arch_elf_pt_proc(void *_ehdr, void *_phdr, struct file *elf, |
| 69 | bool is_interp, struct arch_elf_state *state) |
| 70 | { |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 71 | struct elf32_hdr *ehdr32 = _ehdr; |
| 72 | struct elf32_phdr *phdr32 = _phdr; |
| 73 | struct elf64_phdr *phdr64 = _phdr; |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 74 | struct mips_elf_abiflags_v0 abiflags; |
| 75 | int ret; |
| 76 | |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 77 | /* Lets see if this is an O32 ELF */ |
| 78 | if (ehdr32->e_ident[EI_CLASS] == ELFCLASS32) { |
| 79 | /* FR = 1 for N32 */ |
| 80 | if (ehdr32->e_flags & EF_MIPS_ABI2) |
| 81 | state->overall_fp_mode = FP_FR1; |
| 82 | else |
| 83 | /* Set a good default FPU mode for O32 */ |
| 84 | state->overall_fp_mode = cpu_has_mips_r6 ? |
| 85 | FP_FRE : FP_FR0; |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 86 | |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 87 | if (ehdr32->e_flags & EF_MIPS_FP64) { |
| 88 | /* |
| 89 | * Set MIPS_ABI_FP_OLD_64 for EF_MIPS_FP64. We will override it |
| 90 | * later if needed |
| 91 | */ |
| 92 | if (is_interp) |
| 93 | state->interp_fp_abi = MIPS_ABI_FP_OLD_64; |
| 94 | else |
| 95 | state->fp_abi = MIPS_ABI_FP_OLD_64; |
| 96 | } |
| 97 | if (phdr32->p_type != PT_MIPS_ABIFLAGS) |
| 98 | return 0; |
| 99 | |
| 100 | if (phdr32->p_filesz < sizeof(abiflags)) |
| 101 | return -EINVAL; |
| 102 | |
| 103 | ret = kernel_read(elf, phdr32->p_offset, |
| 104 | (char *)&abiflags, |
| 105 | sizeof(abiflags)); |
| 106 | } else { |
| 107 | /* FR=1 is really the only option for 64-bit */ |
| 108 | state->overall_fp_mode = FP_FR1; |
| 109 | |
| 110 | if (phdr64->p_type != PT_MIPS_ABIFLAGS) |
| 111 | return 0; |
| 112 | if (phdr64->p_filesz < sizeof(abiflags)) |
| 113 | return -EINVAL; |
| 114 | |
| 115 | ret = kernel_read(elf, phdr64->p_offset, |
| 116 | (char *)&abiflags, |
| 117 | sizeof(abiflags)); |
| 118 | } |
| 119 | |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 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 | |
| 131 | return 0; |
| 132 | } |
| 133 | |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 134 | int arch_check_elf(void *_ehdr, bool has_interpreter, |
| 135 | struct arch_elf_state *state) |
| 136 | { |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 137 | struct elf32_hdr *ehdr = _ehdr; |
| 138 | struct mode_req prog_req, interp_req; |
| 139 | int fp_abi, interp_fp_abi, abi0, abi1, max_abi; |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 140 | |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 141 | if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT)) |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 142 | return 0; |
| 143 | |
Maciej W. Rozycki | a49dc42 | 2015-04-03 23:24:41 +0100 | [diff] [blame^] | 144 | fp_abi = state->fp_abi; |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 145 | |
| 146 | if (has_interpreter) { |
Maciej W. Rozycki | a49dc42 | 2015-04-03 23:24:41 +0100 | [diff] [blame^] | 147 | interp_fp_abi = state->interp_fp_abi; |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 148 | |
| 149 | abi0 = min(fp_abi, interp_fp_abi); |
| 150 | abi1 = max(fp_abi, interp_fp_abi); |
| 151 | } else { |
| 152 | abi0 = abi1 = fp_abi; |
| 153 | } |
| 154 | |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 155 | /* ABI limits. O32 = FP_64A, N32/N64 = FP_SOFT */ |
| 156 | max_abi = ((ehdr->e_ident[EI_CLASS] == ELFCLASS32) && |
| 157 | (!(ehdr->e_flags & EF_MIPS_ABI2))) ? |
| 158 | MIPS_ABI_FP_64A : MIPS_ABI_FP_SOFT; |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 159 | |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 160 | if ((abi0 > max_abi && abi0 != MIPS_ABI_FP_UNKNOWN) || |
| 161 | (abi1 > max_abi && abi1 != MIPS_ABI_FP_UNKNOWN)) |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 162 | return -ELIBBAD; |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 163 | |
| 164 | /* It's time to determine the FPU mode requirements */ |
| 165 | prog_req = (abi0 == MIPS_ABI_FP_UNKNOWN) ? none_req : fpu_reqs[abi0]; |
| 166 | interp_req = (abi1 == MIPS_ABI_FP_UNKNOWN) ? none_req : fpu_reqs[abi1]; |
| 167 | |
| 168 | /* |
| 169 | * Check whether the program's and interp's ABIs have a matching FPU |
| 170 | * mode requirement. |
| 171 | */ |
| 172 | prog_req.single = interp_req.single && prog_req.single; |
| 173 | prog_req.soft = interp_req.soft && prog_req.soft; |
| 174 | prog_req.fr1 = interp_req.fr1 && prog_req.fr1; |
| 175 | prog_req.frdefault = interp_req.frdefault && prog_req.frdefault; |
| 176 | prog_req.fre = interp_req.fre && prog_req.fre; |
| 177 | |
| 178 | /* |
| 179 | * Determine the desired FPU mode |
| 180 | * |
| 181 | * Decision making: |
| 182 | * |
| 183 | * - We want FR_FRE if FRE=1 and both FR=1 and FR=0 are false. This |
| 184 | * means that we have a combination of program and interpreter |
| 185 | * that inherently require the hybrid FP mode. |
| 186 | * - If FR1 and FRDEFAULT is true, that means we hit the any-abi or |
| 187 | * fpxx case. This is because, in any-ABI (or no-ABI) we have no FPU |
| 188 | * instructions so we don't care about the mode. We will simply use |
| 189 | * the one preferred by the hardware. In fpxx case, that ABI can |
| 190 | * handle both FR=1 and FR=0, so, again, we simply choose the one |
| 191 | * preferred by the hardware. Next, if we only use single-precision |
| 192 | * FPU instructions, and the default ABI FPU mode is not good |
| 193 | * (ie single + any ABI combination), we set again the FPU mode to the |
| 194 | * one is preferred by the hardware. Next, if we know that the code |
| 195 | * will only use single-precision instructions, shown by single being |
| 196 | * true but frdefault being false, then we again set the FPU mode to |
| 197 | * the one that is preferred by the hardware. |
| 198 | * - We want FP_FR1 if that's the only matching mode and the default one |
| 199 | * is not good. |
| 200 | * - Return with -ELIBADD if we can't find a matching FPU mode. |
| 201 | */ |
| 202 | if (prog_req.fre && !prog_req.frdefault && !prog_req.fr1) |
| 203 | state->overall_fp_mode = FP_FRE; |
| 204 | else if ((prog_req.fr1 && prog_req.frdefault) || |
| 205 | (prog_req.single && !prog_req.frdefault)) |
| 206 | /* Make sure 64-bit MIPS III/IV/64R1 will not pick FR1 */ |
| 207 | state->overall_fp_mode = ((current_cpu_data.fpu_id & MIPS_FPIR_F64) && |
| 208 | cpu_has_mips_r2_r6) ? |
| 209 | FP_FR1 : FP_FR0; |
| 210 | else if (prog_req.fr1) |
| 211 | state->overall_fp_mode = FP_FR1; |
| 212 | else if (!prog_req.fre && !prog_req.frdefault && |
| 213 | !prog_req.fr1 && !prog_req.single && !prog_req.soft) |
| 214 | return -ELIBBAD; |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 215 | |
| 216 | return 0; |
| 217 | } |
| 218 | |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 219 | static inline void set_thread_fp_mode(int hybrid, int regs32) |
| 220 | { |
| 221 | if (hybrid) |
| 222 | set_thread_flag(TIF_HYBRID_FPREGS); |
| 223 | else |
| 224 | clear_thread_flag(TIF_HYBRID_FPREGS); |
| 225 | if (regs32) |
| 226 | set_thread_flag(TIF_32BIT_FPREGS); |
| 227 | else |
| 228 | clear_thread_flag(TIF_32BIT_FPREGS); |
| 229 | } |
| 230 | |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 231 | void mips_set_personality_fp(struct arch_elf_state *state) |
| 232 | { |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 233 | /* |
| 234 | * This function is only ever called for O32 ELFs so we should |
| 235 | * not be worried about N32/N64 binaries. |
| 236 | */ |
Paul Burton | f4af6fb | 2014-09-11 08:30:23 +0100 | [diff] [blame] | 237 | |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 238 | if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT)) |
| 239 | return; |
| 240 | |
| 241 | switch (state->overall_fp_mode) { |
| 242 | case FP_FRE: |
| 243 | set_thread_fp_mode(1, 0); |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 244 | break; |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 245 | case FP_FR0: |
| 246 | set_thread_fp_mode(0, 1); |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 247 | break; |
Markos Chandras | 46490b5 | 2015-01-08 09:32:25 +0000 | [diff] [blame] | 248 | case FP_FR1: |
| 249 | set_thread_fp_mode(0, 0); |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 250 | break; |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 251 | default: |
Paul Burton | 90cee75 | 2014-09-11 08:30:22 +0100 | [diff] [blame] | 252 | BUG(); |
| 253 | } |
| 254 | } |