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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include <linux/binfmts.h>#include <linux/elf.h>#include <linux/export.h>#include <linux/sched.h>
#include <asm/cpu-features.h>#include <asm/cpu-info.h>#include <asm/fpu.h>
#ifdef CONFIG_MIPS_FP_SUPPORT
/* Whether to accept legacy-NaN and 2008-NaN user binaries. */bool mips_use_nan_legacy;bool mips_use_nan_2008;
/* 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){ union { struct elf32_hdr e32; struct elf64_hdr e64; } *ehdr = _ehdr; struct elf32_phdr *phdr32 = _phdr; struct elf64_phdr *phdr64 = _phdr; struct mips_elf_abiflags_v0 abiflags; bool elf32; u32 flags; int ret; loff_t pos;
elf32 = ehdr->e32.e_ident[EI_CLASS] == ELFCLASS32; flags = elf32 ? ehdr->e32.e_flags : ehdr->e64.e_flags;
/* Let's see if this is an O32 ELF */ if (elf32) { if (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; pos = phdr32->p_offset; } else { if (phdr64->p_type != PT_MIPS_ABIFLAGS) return 0; if (phdr64->p_filesz < sizeof(abiflags)) return -EINVAL; pos = phdr64->p_offset; }
ret = kernel_read(elf, &abiflags, sizeof(abiflags), &pos); 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, void *_interp_ehdr, struct arch_elf_state *state){ union { struct elf32_hdr e32; struct elf64_hdr e64; } *ehdr = _ehdr; union { struct elf32_hdr e32; struct elf64_hdr e64; } *iehdr = _interp_ehdr; struct mode_req prog_req, interp_req; int fp_abi, interp_fp_abi, abi0, abi1, max_abi; bool elf32; u32 flags;
elf32 = ehdr->e32.e_ident[EI_CLASS] == ELFCLASS32; flags = elf32 ? ehdr->e32.e_flags : ehdr->e64.e_flags;
/* * Determine the NaN personality, reject the binary if not allowed. * Also ensure that any interpreter matches the executable. */ if (flags & EF_MIPS_NAN2008) { if (mips_use_nan_2008) state->nan_2008 = 1; else return -ENOEXEC; } else { if (mips_use_nan_legacy) state->nan_2008 = 0; else return -ENOEXEC; } if (has_interpreter) { bool ielf32; u32 iflags;
ielf32 = iehdr->e32.e_ident[EI_CLASS] == ELFCLASS32; iflags = ielf32 ? iehdr->e32.e_flags : iehdr->e64.e_flags;
if ((flags ^ iflags) & EF_MIPS_NAN2008) return -ELIBBAD; }
if (!IS_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; }
if (elf32 && !(flags & EF_MIPS_ABI2)) { /* 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; } else { /* 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; }
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 (!IS_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(); }}
/* * Select the IEEE 754 NaN encoding and ABS.fmt/NEG.fmt execution mode * in FCSR according to the ELF NaN personality. */void mips_set_personality_nan(struct arch_elf_state *state){ struct cpuinfo_mips *c = &boot_cpu_data; struct task_struct *t = current;
/* Do this early so t->thread.fpu.fcr31 won't be clobbered in case * we are preempted before the lose_fpu(0) in start_thread. */ lose_fpu(0);
t->thread.fpu.fcr31 = c->fpu_csr31; switch (state->nan_2008) { case 0: if (!(c->fpu_msk31 & FPU_CSR_NAN2008)) t->thread.fpu.fcr31 &= ~FPU_CSR_NAN2008; if (!(c->fpu_msk31 & FPU_CSR_ABS2008)) t->thread.fpu.fcr31 &= ~FPU_CSR_ABS2008; break; case 1: if (!(c->fpu_msk31 & FPU_CSR_NAN2008)) t->thread.fpu.fcr31 |= FPU_CSR_NAN2008; if (!(c->fpu_msk31 & FPU_CSR_ABS2008)) t->thread.fpu.fcr31 |= FPU_CSR_ABS2008; break; default: BUG(); }}
#endif /* CONFIG_MIPS_FP_SUPPORT */
int mips_elf_read_implies_exec(void *elf_ex, int exstack){ /* * Set READ_IMPLIES_EXEC only on non-NX systems that * do not request a specific state via PT_GNU_STACK. */ return (!cpu_has_rixi && exstack == EXSTACK_DEFAULT);}EXPORT_SYMBOL(mips_elf_read_implies_exec);