2 * Copyright (C) 2014 Imagination Technologies
3 * Author: Paul Burton <paul.burton@imgtec.com>
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.
11 #include <linux/elf.h>
12 #include <linux/sched.h>
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
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
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
37 * More information about the FP ABIs can be found here:
39 * https://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking#10.4.1._Basic_mode_set-up
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 }
63 * Mode requirements when .MIPS.abiflags is not present in the ELF.
64 * Not present means that everything is acceptable except FR1.
66 static struct mode_req none_req = { true, true, false, true, true };
68 int arch_elf_pt_proc(void *_ehdr, void *_phdr, struct file *elf,
69 bool is_interp, struct arch_elf_state *state)
71 struct elf32_hdr *ehdr32 = _ehdr;
72 struct elf32_phdr *phdr32 = _phdr;
73 struct elf64_phdr *phdr64 = _phdr;
74 struct mips_elf_abiflags_v0 abiflags;
77 /* Lets see if this is an O32 ELF */
78 if (ehdr32->e_ident[EI_CLASS] == ELFCLASS32) {
79 if (ehdr32->e_flags & EF_MIPS_FP64) {
81 * Set MIPS_ABI_FP_OLD_64 for EF_MIPS_FP64. We will override it
85 state->interp_fp_abi = MIPS_ABI_FP_OLD_64;
87 state->fp_abi = MIPS_ABI_FP_OLD_64;
89 if (phdr32->p_type != PT_MIPS_ABIFLAGS)
92 if (phdr32->p_filesz < sizeof(abiflags))
95 ret = kernel_read(elf, phdr32->p_offset,
99 if (phdr64->p_type != PT_MIPS_ABIFLAGS)
101 if (phdr64->p_filesz < sizeof(abiflags))
104 ret = kernel_read(elf, phdr64->p_offset,
111 if (ret != sizeof(abiflags))
114 /* Record the required FP ABIs for use by mips_check_elf */
116 state->interp_fp_abi = abiflags.fp_abi;
118 state->fp_abi = abiflags.fp_abi;
123 int arch_check_elf(void *_ehdr, bool has_interpreter,
124 struct arch_elf_state *state)
126 struct elf32_hdr *ehdr = _ehdr;
127 struct mode_req prog_req, interp_req;
128 int fp_abi, interp_fp_abi, abi0, abi1, max_abi;
131 if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT))
134 fp_abi = state->fp_abi;
136 if (has_interpreter) {
137 interp_fp_abi = state->interp_fp_abi;
139 abi0 = min(fp_abi, interp_fp_abi);
140 abi1 = max(fp_abi, interp_fp_abi);
142 abi0 = abi1 = fp_abi;
145 is_mips64 = (ehdr->e_ident[EI_CLASS] == ELFCLASS64) ||
146 (ehdr->e_flags & EF_MIPS_ABI2);
149 /* MIPS64 code always uses FR=1, thus the default is easy */
150 state->overall_fp_mode = FP_FR1;
152 /* Disallow access to the various FPXX & FP64 ABIs */
153 max_abi = MIPS_ABI_FP_SOFT;
155 /* Default to a mode capable of running code expecting FR=0 */
156 state->overall_fp_mode = cpu_has_mips_r6 ? FP_FRE : FP_FR0;
158 /* Allow all ABIs we know about */
159 max_abi = MIPS_ABI_FP_64A;
162 if ((abi0 > max_abi && abi0 != MIPS_ABI_FP_UNKNOWN) ||
163 (abi1 > max_abi && abi1 != MIPS_ABI_FP_UNKNOWN))
166 /* It's time to determine the FPU mode requirements */
167 prog_req = (abi0 == MIPS_ABI_FP_UNKNOWN) ? none_req : fpu_reqs[abi0];
168 interp_req = (abi1 == MIPS_ABI_FP_UNKNOWN) ? none_req : fpu_reqs[abi1];
171 * Check whether the program's and interp's ABIs have a matching FPU
174 prog_req.single = interp_req.single && prog_req.single;
175 prog_req.soft = interp_req.soft && prog_req.soft;
176 prog_req.fr1 = interp_req.fr1 && prog_req.fr1;
177 prog_req.frdefault = interp_req.frdefault && prog_req.frdefault;
178 prog_req.fre = interp_req.fre && prog_req.fre;
181 * Determine the desired FPU mode
185 * - We want FR_FRE if FRE=1 and both FR=1 and FR=0 are false. This
186 * means that we have a combination of program and interpreter
187 * that inherently require the hybrid FP mode.
188 * - If FR1 and FRDEFAULT is true, that means we hit the any-abi or
189 * fpxx case. This is because, in any-ABI (or no-ABI) we have no FPU
190 * instructions so we don't care about the mode. We will simply use
191 * the one preferred by the hardware. In fpxx case, that ABI can
192 * handle both FR=1 and FR=0, so, again, we simply choose the one
193 * preferred by the hardware. Next, if we only use single-precision
194 * FPU instructions, and the default ABI FPU mode is not good
195 * (ie single + any ABI combination), we set again the FPU mode to the
196 * one is preferred by the hardware. Next, if we know that the code
197 * will only use single-precision instructions, shown by single being
198 * true but frdefault being false, then we again set the FPU mode to
199 * the one that is preferred by the hardware.
200 * - We want FP_FR1 if that's the only matching mode and the default one
202 * - Return with -ELIBADD if we can't find a matching FPU mode.
204 if (prog_req.fre && !prog_req.frdefault && !prog_req.fr1)
205 state->overall_fp_mode = FP_FRE;
206 else if ((prog_req.fr1 && prog_req.frdefault) ||
207 (prog_req.single && !prog_req.frdefault))
208 /* Make sure 64-bit MIPS III/IV/64R1 will not pick FR1 */
209 state->overall_fp_mode = ((current_cpu_data.fpu_id & MIPS_FPIR_F64) &&
210 cpu_has_mips_r2_r6) ?
212 else if (prog_req.fr1)
213 state->overall_fp_mode = FP_FR1;
214 else if (!prog_req.fre && !prog_req.frdefault &&
215 !prog_req.fr1 && !prog_req.single && !prog_req.soft)
221 static inline void set_thread_fp_mode(int hybrid, int regs32)
224 set_thread_flag(TIF_HYBRID_FPREGS);
226 clear_thread_flag(TIF_HYBRID_FPREGS);
228 set_thread_flag(TIF_32BIT_FPREGS);
230 clear_thread_flag(TIF_32BIT_FPREGS);
233 void mips_set_personality_fp(struct arch_elf_state *state)
236 * This function is only ever called for O32 ELFs so we should
237 * not be worried about N32/N64 binaries.
240 if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT))
243 switch (state->overall_fp_mode) {
245 set_thread_fp_mode(1, 0);
248 set_thread_fp_mode(0, 1);
251 set_thread_fp_mode(0, 0);