/* * Copyright (C) 2014 Imagination Technologies * Author: Paul Burton * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation; either version 2 of the License, or (at your * option) any later version. */ #include #include #include /* FPU modes */ enum { FP_FRE, FP_FR0, FP_FR1, }; /** * struct mode_req - ABI FPU mode requirements * @single: The program being loaded needs an FPU but it will only issue * single precision instructions meaning that it can execute in * either FR0 or FR1. * @soft: The soft(-float) requirement means that the program being * loaded needs has no FPU dependency at all (i.e. it has no * FPU instructions). * @fr1: The program being loaded depends on FPU being in FR=1 mode. * @frdefault: The program being loaded depends on the default FPU mode. * That is FR0 for O32 and FR1 for N32/N64. * @fre: The program being loaded depends on FPU with FRE=1. This mode is * a bridge which uses FR=1 whilst still being able to maintain * full compatibility with pre-existing code using the O32 FP32 * ABI. * * More information about the FP ABIs can be found here: * * https://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking#10.4.1._Basic_mode_set-up * */ struct mode_req { bool single; bool soft; bool fr1; bool frdefault; bool fre; }; static const struct mode_req fpu_reqs[] = { [MIPS_ABI_FP_ANY] = { true, true, true, true, true }, [MIPS_ABI_FP_DOUBLE] = { false, false, false, true, true }, [MIPS_ABI_FP_SINGLE] = { true, false, false, false, false }, [MIPS_ABI_FP_SOFT] = { false, true, false, false, false }, [MIPS_ABI_FP_OLD_64] = { false, false, false, false, false }, [MIPS_ABI_FP_XX] = { false, false, true, true, true }, [MIPS_ABI_FP_64] = { false, false, true, false, false }, [MIPS_ABI_FP_64A] = { false, false, true, false, true } }; /* * Mode requirements when .MIPS.abiflags is not present in the ELF. * Not present means that everything is acceptable except FR1. */ static struct mode_req none_req = { true, true, false, true, true }; int arch_elf_pt_proc(void *_ehdr, void *_phdr, struct file *elf, bool is_interp, struct arch_elf_state *state) { struct elf32_hdr *ehdr32 = _ehdr; struct elf32_phdr *phdr32 = _phdr; struct elf64_phdr *phdr64 = _phdr; struct mips_elf_abiflags_v0 abiflags; int ret; /* Lets see if this is an O32 ELF */ if (ehdr32->e_ident[EI_CLASS] == ELFCLASS32) { if (ehdr32->e_flags & EF_MIPS_FP64) { /* * Set MIPS_ABI_FP_OLD_64 for EF_MIPS_FP64. We will override it * later if needed */ if (is_interp) state->interp_fp_abi = MIPS_ABI_FP_OLD_64; else state->fp_abi = MIPS_ABI_FP_OLD_64; } if (phdr32->p_type != PT_MIPS_ABIFLAGS) return 0; if (phdr32->p_filesz < sizeof(abiflags)) return -EINVAL; ret = kernel_read(elf, phdr32->p_offset, (char *)&abiflags, sizeof(abiflags)); } else { if (phdr64->p_type != PT_MIPS_ABIFLAGS) return 0; if (phdr64->p_filesz < sizeof(abiflags)) return -EINVAL; ret = kernel_read(elf, phdr64->p_offset, (char *)&abiflags, sizeof(abiflags)); } if (ret < 0) return ret; if (ret != sizeof(abiflags)) return -EIO; /* Record the required FP ABIs for use by mips_check_elf */ if (is_interp) state->interp_fp_abi = abiflags.fp_abi; else state->fp_abi = abiflags.fp_abi; return 0; } int arch_check_elf(void *_ehdr, bool has_interpreter, struct arch_elf_state *state) { struct elf32_hdr *ehdr = _ehdr; struct mode_req prog_req, interp_req; int fp_abi, interp_fp_abi, abi0, abi1, max_abi; bool is_mips64; if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT)) return 0; fp_abi = state->fp_abi; if (has_interpreter) { interp_fp_abi = state->interp_fp_abi; abi0 = min(fp_abi, interp_fp_abi); abi1 = max(fp_abi, interp_fp_abi); } else { abi0 = abi1 = fp_abi; } is_mips64 = (ehdr->e_ident[EI_CLASS] == ELFCLASS64) || (ehdr->e_flags & EF_MIPS_ABI2); if (is_mips64) { /* MIPS64 code always uses FR=1, thus the default is easy */ state->overall_fp_mode = FP_FR1; /* Disallow access to the various FPXX & FP64 ABIs */ max_abi = MIPS_ABI_FP_SOFT; } else { /* Default to a mode capable of running code expecting FR=0 */ state->overall_fp_mode = cpu_has_mips_r6 ? FP_FRE : FP_FR0; /* Allow all ABIs we know about */ max_abi = MIPS_ABI_FP_64A; } if ((abi0 > max_abi && abi0 != MIPS_ABI_FP_UNKNOWN) || (abi1 > max_abi && abi1 != MIPS_ABI_FP_UNKNOWN)) return -ELIBBAD; /* It's time to determine the FPU mode requirements */ prog_req = (abi0 == MIPS_ABI_FP_UNKNOWN) ? none_req : fpu_reqs[abi0]; interp_req = (abi1 == MIPS_ABI_FP_UNKNOWN) ? none_req : fpu_reqs[abi1]; /* * Check whether the program's and interp's ABIs have a matching FPU * mode requirement. */ prog_req.single = interp_req.single && prog_req.single; prog_req.soft = interp_req.soft && prog_req.soft; prog_req.fr1 = interp_req.fr1 && prog_req.fr1; prog_req.frdefault = interp_req.frdefault && prog_req.frdefault; prog_req.fre = interp_req.fre && prog_req.fre; /* * Determine the desired FPU mode * * Decision making: * * - We want FR_FRE if FRE=1 and both FR=1 and FR=0 are false. This * means that we have a combination of program and interpreter * that inherently require the hybrid FP mode. * - If FR1 and FRDEFAULT is true, that means we hit the any-abi or * fpxx case. This is because, in any-ABI (or no-ABI) we have no FPU * instructions so we don't care about the mode. We will simply use * the one preferred by the hardware. In fpxx case, that ABI can * handle both FR=1 and FR=0, so, again, we simply choose the one * preferred by the hardware. Next, if we only use single-precision * FPU instructions, and the default ABI FPU mode is not good * (ie single + any ABI combination), we set again the FPU mode to the * one is preferred by the hardware. Next, if we know that the code * will only use single-precision instructions, shown by single being * true but frdefault being false, then we again set the FPU mode to * the one that is preferred by the hardware. * - We want FP_FR1 if that's the only matching mode and the default one * is not good. * - Return with -ELIBADD if we can't find a matching FPU mode. */ if (prog_req.fre && !prog_req.frdefault && !prog_req.fr1) state->overall_fp_mode = FP_FRE; else if ((prog_req.fr1 && prog_req.frdefault) || (prog_req.single && !prog_req.frdefault)) /* Make sure 64-bit MIPS III/IV/64R1 will not pick FR1 */ state->overall_fp_mode = ((raw_current_cpu_data.fpu_id & MIPS_FPIR_F64) && cpu_has_mips_r2_r6) ? FP_FR1 : FP_FR0; else if (prog_req.fr1) state->overall_fp_mode = FP_FR1; else if (!prog_req.fre && !prog_req.frdefault && !prog_req.fr1 && !prog_req.single && !prog_req.soft) return -ELIBBAD; return 0; } static inline void set_thread_fp_mode(int hybrid, int regs32) { if (hybrid) set_thread_flag(TIF_HYBRID_FPREGS); else clear_thread_flag(TIF_HYBRID_FPREGS); if (regs32) set_thread_flag(TIF_32BIT_FPREGS); else clear_thread_flag(TIF_32BIT_FPREGS); } void mips_set_personality_fp(struct arch_elf_state *state) { /* * This function is only ever called for O32 ELFs so we should * not be worried about N32/N64 binaries. */ if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT)) return; switch (state->overall_fp_mode) { case FP_FRE: set_thread_fp_mode(1, 0); break; case FP_FR0: set_thread_fp_mode(0, 1); break; case FP_FR1: set_thread_fp_mode(0, 0); break; default: BUG(); } }