190cee759SPaul Burton /* 290cee759SPaul Burton * Copyright (C) 2014 Imagination Technologies 390cee759SPaul Burton * Author: Paul Burton <paul.burton@imgtec.com> 490cee759SPaul Burton * 590cee759SPaul Burton * This program is free software; you can redistribute it and/or modify it 690cee759SPaul Burton * under the terms of the GNU General Public License as published by the 790cee759SPaul Burton * Free Software Foundation; either version 2 of the License, or (at your 890cee759SPaul Burton * option) any later version. 990cee759SPaul Burton */ 1090cee759SPaul Burton 1190cee759SPaul Burton #include <linux/elf.h> 1290cee759SPaul Burton #include <linux/sched.h> 1390cee759SPaul Burton 1446490b57SMarkos Chandras /* FPU modes */ 1590cee759SPaul Burton enum { 1646490b57SMarkos Chandras FP_FRE, 1746490b57SMarkos Chandras FP_FR0, 1846490b57SMarkos Chandras FP_FR1, 1990cee759SPaul Burton }; 2090cee759SPaul Burton 2146490b57SMarkos Chandras /** 2246490b57SMarkos Chandras * struct mode_req - ABI FPU mode requirements 2346490b57SMarkos Chandras * @single: The program being loaded needs an FPU but it will only issue 2446490b57SMarkos Chandras * single precision instructions meaning that it can execute in 2546490b57SMarkos Chandras * either FR0 or FR1. 2646490b57SMarkos Chandras * @soft: The soft(-float) requirement means that the program being 2746490b57SMarkos Chandras * loaded needs has no FPU dependency at all (i.e. it has no 2846490b57SMarkos Chandras * FPU instructions). 2946490b57SMarkos Chandras * @fr1: The program being loaded depends on FPU being in FR=1 mode. 3046490b57SMarkos Chandras * @frdefault: The program being loaded depends on the default FPU mode. 3146490b57SMarkos Chandras * That is FR0 for O32 and FR1 for N32/N64. 3246490b57SMarkos Chandras * @fre: The program being loaded depends on FPU with FRE=1. This mode is 3346490b57SMarkos Chandras * a bridge which uses FR=1 whilst still being able to maintain 3446490b57SMarkos Chandras * full compatibility with pre-existing code using the O32 FP32 3546490b57SMarkos Chandras * ABI. 3646490b57SMarkos Chandras * 3746490b57SMarkos Chandras * More information about the FP ABIs can be found here: 3846490b57SMarkos Chandras * 3946490b57SMarkos Chandras * https://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking#10.4.1._Basic_mode_set-up 4046490b57SMarkos Chandras * 4146490b57SMarkos Chandras */ 4246490b57SMarkos Chandras 4346490b57SMarkos Chandras struct mode_req { 4446490b57SMarkos Chandras bool single; 4546490b57SMarkos Chandras bool soft; 4646490b57SMarkos Chandras bool fr1; 4746490b57SMarkos Chandras bool frdefault; 4846490b57SMarkos Chandras bool fre; 4946490b57SMarkos Chandras }; 5046490b57SMarkos Chandras 5146490b57SMarkos Chandras static const struct mode_req fpu_reqs[] = { 5246490b57SMarkos Chandras [MIPS_ABI_FP_ANY] = { true, true, true, true, true }, 5346490b57SMarkos Chandras [MIPS_ABI_FP_DOUBLE] = { false, false, false, true, true }, 5446490b57SMarkos Chandras [MIPS_ABI_FP_SINGLE] = { true, false, false, false, false }, 5546490b57SMarkos Chandras [MIPS_ABI_FP_SOFT] = { false, true, false, false, false }, 5646490b57SMarkos Chandras [MIPS_ABI_FP_OLD_64] = { false, false, false, false, false }, 5746490b57SMarkos Chandras [MIPS_ABI_FP_XX] = { false, false, true, true, true }, 5846490b57SMarkos Chandras [MIPS_ABI_FP_64] = { false, false, true, false, false }, 5946490b57SMarkos Chandras [MIPS_ABI_FP_64A] = { false, false, true, false, true } 6046490b57SMarkos Chandras }; 6146490b57SMarkos Chandras 6246490b57SMarkos Chandras /* 6346490b57SMarkos Chandras * Mode requirements when .MIPS.abiflags is not present in the ELF. 6446490b57SMarkos Chandras * Not present means that everything is acceptable except FR1. 6546490b57SMarkos Chandras */ 6646490b57SMarkos Chandras static struct mode_req none_req = { true, true, false, true, true }; 6746490b57SMarkos Chandras 6890cee759SPaul Burton int arch_elf_pt_proc(void *_ehdr, void *_phdr, struct file *elf, 6990cee759SPaul Burton bool is_interp, struct arch_elf_state *state) 7090cee759SPaul Burton { 7146490b57SMarkos Chandras struct elf32_hdr *ehdr32 = _ehdr; 7246490b57SMarkos Chandras struct elf32_phdr *phdr32 = _phdr; 7346490b57SMarkos Chandras struct elf64_phdr *phdr64 = _phdr; 7490cee759SPaul Burton struct mips_elf_abiflags_v0 abiflags; 7590cee759SPaul Burton int ret; 7690cee759SPaul Burton 7746490b57SMarkos Chandras /* Lets see if this is an O32 ELF */ 7846490b57SMarkos Chandras if (ehdr32->e_ident[EI_CLASS] == ELFCLASS32) { 7946490b57SMarkos Chandras /* FR = 1 for N32 */ 8046490b57SMarkos Chandras if (ehdr32->e_flags & EF_MIPS_ABI2) 8146490b57SMarkos Chandras state->overall_fp_mode = FP_FR1; 8246490b57SMarkos Chandras else 8346490b57SMarkos Chandras /* Set a good default FPU mode for O32 */ 8446490b57SMarkos Chandras state->overall_fp_mode = cpu_has_mips_r6 ? 8546490b57SMarkos Chandras FP_FRE : FP_FR0; 8646490b57SMarkos Chandras 8746490b57SMarkos Chandras if (ehdr32->e_flags & EF_MIPS_FP64) { 8846490b57SMarkos Chandras /* 8946490b57SMarkos Chandras * Set MIPS_ABI_FP_OLD_64 for EF_MIPS_FP64. We will override it 9046490b57SMarkos Chandras * later if needed 9146490b57SMarkos Chandras */ 9246490b57SMarkos Chandras if (is_interp) 9346490b57SMarkos Chandras state->interp_fp_abi = MIPS_ABI_FP_OLD_64; 9446490b57SMarkos Chandras else 9546490b57SMarkos Chandras state->fp_abi = MIPS_ABI_FP_OLD_64; 9646490b57SMarkos Chandras } 9746490b57SMarkos Chandras if (phdr32->p_type != PT_MIPS_ABIFLAGS) 9890cee759SPaul Burton return 0; 9946490b57SMarkos Chandras 10046490b57SMarkos Chandras if (phdr32->p_filesz < sizeof(abiflags)) 10190cee759SPaul Burton return -EINVAL; 10290cee759SPaul Burton 10346490b57SMarkos Chandras ret = kernel_read(elf, phdr32->p_offset, 10446490b57SMarkos Chandras (char *)&abiflags, 10590cee759SPaul Burton sizeof(abiflags)); 10646490b57SMarkos Chandras } else { 10746490b57SMarkos Chandras /* FR=1 is really the only option for 64-bit */ 10846490b57SMarkos Chandras state->overall_fp_mode = FP_FR1; 10946490b57SMarkos Chandras 11046490b57SMarkos Chandras if (phdr64->p_type != PT_MIPS_ABIFLAGS) 11146490b57SMarkos Chandras return 0; 11246490b57SMarkos Chandras if (phdr64->p_filesz < sizeof(abiflags)) 11346490b57SMarkos Chandras return -EINVAL; 11446490b57SMarkos Chandras 11546490b57SMarkos Chandras ret = kernel_read(elf, phdr64->p_offset, 11646490b57SMarkos Chandras (char *)&abiflags, 11746490b57SMarkos Chandras sizeof(abiflags)); 11846490b57SMarkos Chandras } 11946490b57SMarkos Chandras 12090cee759SPaul Burton if (ret < 0) 12190cee759SPaul Burton return ret; 12290cee759SPaul Burton if (ret != sizeof(abiflags)) 12390cee759SPaul Burton return -EIO; 12490cee759SPaul Burton 12590cee759SPaul Burton /* Record the required FP ABIs for use by mips_check_elf */ 12690cee759SPaul Burton if (is_interp) 12790cee759SPaul Burton state->interp_fp_abi = abiflags.fp_abi; 12890cee759SPaul Burton else 12990cee759SPaul Burton state->fp_abi = abiflags.fp_abi; 13090cee759SPaul Burton 13190cee759SPaul Burton return 0; 13290cee759SPaul Burton } 13390cee759SPaul Burton 13490cee759SPaul Burton int arch_check_elf(void *_ehdr, bool has_interpreter, 13590cee759SPaul Burton struct arch_elf_state *state) 13690cee759SPaul Burton { 13746490b57SMarkos Chandras struct elf32_hdr *ehdr = _ehdr; 13846490b57SMarkos Chandras struct mode_req prog_req, interp_req; 13946490b57SMarkos Chandras int fp_abi, interp_fp_abi, abi0, abi1, max_abi; 14090cee759SPaul Burton 14146490b57SMarkos Chandras if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT)) 14290cee759SPaul Burton return 0; 14390cee759SPaul Burton 144*a49dc427SMaciej W. Rozycki fp_abi = state->fp_abi; 14590cee759SPaul Burton 14690cee759SPaul Burton if (has_interpreter) { 147*a49dc427SMaciej W. Rozycki interp_fp_abi = state->interp_fp_abi; 14890cee759SPaul Burton 14990cee759SPaul Burton abi0 = min(fp_abi, interp_fp_abi); 15090cee759SPaul Burton abi1 = max(fp_abi, interp_fp_abi); 15190cee759SPaul Burton } else { 15290cee759SPaul Burton abi0 = abi1 = fp_abi; 15390cee759SPaul Burton } 15490cee759SPaul Burton 15546490b57SMarkos Chandras /* ABI limits. O32 = FP_64A, N32/N64 = FP_SOFT */ 15646490b57SMarkos Chandras max_abi = ((ehdr->e_ident[EI_CLASS] == ELFCLASS32) && 15746490b57SMarkos Chandras (!(ehdr->e_flags & EF_MIPS_ABI2))) ? 15846490b57SMarkos Chandras MIPS_ABI_FP_64A : MIPS_ABI_FP_SOFT; 15990cee759SPaul Burton 16046490b57SMarkos Chandras if ((abi0 > max_abi && abi0 != MIPS_ABI_FP_UNKNOWN) || 16146490b57SMarkos Chandras (abi1 > max_abi && abi1 != MIPS_ABI_FP_UNKNOWN)) 16290cee759SPaul Burton return -ELIBBAD; 16390cee759SPaul Burton 16446490b57SMarkos Chandras /* It's time to determine the FPU mode requirements */ 16546490b57SMarkos Chandras prog_req = (abi0 == MIPS_ABI_FP_UNKNOWN) ? none_req : fpu_reqs[abi0]; 16646490b57SMarkos Chandras interp_req = (abi1 == MIPS_ABI_FP_UNKNOWN) ? none_req : fpu_reqs[abi1]; 16746490b57SMarkos Chandras 16846490b57SMarkos Chandras /* 16946490b57SMarkos Chandras * Check whether the program's and interp's ABIs have a matching FPU 17046490b57SMarkos Chandras * mode requirement. 17146490b57SMarkos Chandras */ 17246490b57SMarkos Chandras prog_req.single = interp_req.single && prog_req.single; 17346490b57SMarkos Chandras prog_req.soft = interp_req.soft && prog_req.soft; 17446490b57SMarkos Chandras prog_req.fr1 = interp_req.fr1 && prog_req.fr1; 17546490b57SMarkos Chandras prog_req.frdefault = interp_req.frdefault && prog_req.frdefault; 17646490b57SMarkos Chandras prog_req.fre = interp_req.fre && prog_req.fre; 17746490b57SMarkos Chandras 17846490b57SMarkos Chandras /* 17946490b57SMarkos Chandras * Determine the desired FPU mode 18046490b57SMarkos Chandras * 18146490b57SMarkos Chandras * Decision making: 18246490b57SMarkos Chandras * 18346490b57SMarkos Chandras * - We want FR_FRE if FRE=1 and both FR=1 and FR=0 are false. This 18446490b57SMarkos Chandras * means that we have a combination of program and interpreter 18546490b57SMarkos Chandras * that inherently require the hybrid FP mode. 18646490b57SMarkos Chandras * - If FR1 and FRDEFAULT is true, that means we hit the any-abi or 18746490b57SMarkos Chandras * fpxx case. This is because, in any-ABI (or no-ABI) we have no FPU 18846490b57SMarkos Chandras * instructions so we don't care about the mode. We will simply use 18946490b57SMarkos Chandras * the one preferred by the hardware. In fpxx case, that ABI can 19046490b57SMarkos Chandras * handle both FR=1 and FR=0, so, again, we simply choose the one 19146490b57SMarkos Chandras * preferred by the hardware. Next, if we only use single-precision 19246490b57SMarkos Chandras * FPU instructions, and the default ABI FPU mode is not good 19346490b57SMarkos Chandras * (ie single + any ABI combination), we set again the FPU mode to the 19446490b57SMarkos Chandras * one is preferred by the hardware. Next, if we know that the code 19546490b57SMarkos Chandras * will only use single-precision instructions, shown by single being 19646490b57SMarkos Chandras * true but frdefault being false, then we again set the FPU mode to 19746490b57SMarkos Chandras * the one that is preferred by the hardware. 19846490b57SMarkos Chandras * - We want FP_FR1 if that's the only matching mode and the default one 19946490b57SMarkos Chandras * is not good. 20046490b57SMarkos Chandras * - Return with -ELIBADD if we can't find a matching FPU mode. 20146490b57SMarkos Chandras */ 20246490b57SMarkos Chandras if (prog_req.fre && !prog_req.frdefault && !prog_req.fr1) 20346490b57SMarkos Chandras state->overall_fp_mode = FP_FRE; 20446490b57SMarkos Chandras else if ((prog_req.fr1 && prog_req.frdefault) || 20546490b57SMarkos Chandras (prog_req.single && !prog_req.frdefault)) 20646490b57SMarkos Chandras /* Make sure 64-bit MIPS III/IV/64R1 will not pick FR1 */ 20746490b57SMarkos Chandras state->overall_fp_mode = ((current_cpu_data.fpu_id & MIPS_FPIR_F64) && 20846490b57SMarkos Chandras cpu_has_mips_r2_r6) ? 20946490b57SMarkos Chandras FP_FR1 : FP_FR0; 21046490b57SMarkos Chandras else if (prog_req.fr1) 21146490b57SMarkos Chandras state->overall_fp_mode = FP_FR1; 21246490b57SMarkos Chandras else if (!prog_req.fre && !prog_req.frdefault && 21346490b57SMarkos Chandras !prog_req.fr1 && !prog_req.single && !prog_req.soft) 21490cee759SPaul Burton return -ELIBBAD; 21590cee759SPaul Burton 21690cee759SPaul Burton return 0; 21790cee759SPaul Burton } 21890cee759SPaul Burton 21946490b57SMarkos Chandras static inline void set_thread_fp_mode(int hybrid, int regs32) 22090cee759SPaul Burton { 22146490b57SMarkos Chandras if (hybrid) 222f4af6fb2SPaul Burton set_thread_flag(TIF_HYBRID_FPREGS); 22346490b57SMarkos Chandras else 22490cee759SPaul Burton clear_thread_flag(TIF_HYBRID_FPREGS); 22546490b57SMarkos Chandras if (regs32) 22690cee759SPaul Burton set_thread_flag(TIF_32BIT_FPREGS); 22790cee759SPaul Burton else 22890cee759SPaul Burton clear_thread_flag(TIF_32BIT_FPREGS); 22946490b57SMarkos Chandras } 23090cee759SPaul Burton 23146490b57SMarkos Chandras void mips_set_personality_fp(struct arch_elf_state *state) 23246490b57SMarkos Chandras { 23346490b57SMarkos Chandras /* 23446490b57SMarkos Chandras * This function is only ever called for O32 ELFs so we should 23546490b57SMarkos Chandras * not be worried about N32/N64 binaries. 23646490b57SMarkos Chandras */ 23746490b57SMarkos Chandras 23846490b57SMarkos Chandras if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT)) 23946490b57SMarkos Chandras return; 24046490b57SMarkos Chandras 24146490b57SMarkos Chandras switch (state->overall_fp_mode) { 24246490b57SMarkos Chandras case FP_FRE: 24346490b57SMarkos Chandras set_thread_fp_mode(1, 0); 24490cee759SPaul Burton break; 24546490b57SMarkos Chandras case FP_FR0: 24646490b57SMarkos Chandras set_thread_fp_mode(0, 1); 24746490b57SMarkos Chandras break; 24846490b57SMarkos Chandras case FP_FR1: 24946490b57SMarkos Chandras set_thread_fp_mode(0, 0); 25046490b57SMarkos Chandras break; 25190cee759SPaul Burton default: 25290cee759SPaul Burton BUG(); 25390cee759SPaul Burton } 25490cee759SPaul Burton } 255