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Diffstat (limited to 'kernel/arch/mips/kernel/elf.c')
-rw-r--r-- | kernel/arch/mips/kernel/elf.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/kernel/arch/mips/kernel/elf.c b/kernel/arch/mips/kernel/elf.c new file mode 100644 index 000000000..4a4d9e067 --- /dev/null +++ b/kernel/arch/mips/kernel/elf.c @@ -0,0 +1,256 @@ +/* + * Copyright (C) 2014 Imagination Technologies + * Author: Paul Burton <paul.burton@imgtec.com> + * + * 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 <linux/elf.h> +#include <linux/sched.h> + +/* 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 = ((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(); + } +} |