1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/export.h> 3 #include <linux/sched.h> 4 #include <linux/personality.h> 5 #include <linux/binfmts.h> 6 #include <linux/elf.h> 7 #include <linux/elf-fdpic.h> 8 #include <asm/system_info.h> 9 10 int elf_check_arch(const struct elf32_hdr *x) 11 { 12 unsigned int eflags; 13 14 /* Make sure it's an ARM executable */ 15 if (x->e_machine != EM_ARM) 16 return 0; 17 18 /* Make sure the entry address is reasonable */ 19 if (x->e_entry & 1) { 20 if (!(elf_hwcap & HWCAP_THUMB)) 21 return 0; 22 } else if (x->e_entry & 3) 23 return 0; 24 25 eflags = x->e_flags; 26 if ((eflags & EF_ARM_EABI_MASK) == EF_ARM_EABI_UNKNOWN) { 27 unsigned int flt_fmt; 28 29 /* APCS26 is only allowed if the CPU supports it */ 30 if ((eflags & EF_ARM_APCS_26) && !(elf_hwcap & HWCAP_26BIT)) 31 return 0; 32 33 flt_fmt = eflags & (EF_ARM_VFP_FLOAT | EF_ARM_SOFT_FLOAT); 34 35 /* VFP requires the supporting code */ 36 if (flt_fmt == EF_ARM_VFP_FLOAT && !(elf_hwcap & HWCAP_VFP)) 37 return 0; 38 } 39 return 1; 40 } 41 EXPORT_SYMBOL(elf_check_arch); 42 43 void elf_set_personality(const struct elf32_hdr *x) 44 { 45 unsigned int eflags = x->e_flags; 46 unsigned int personality = current->personality & ~PER_MASK; 47 48 /* 49 * We only support Linux ELF executables, so always set the 50 * personality to LINUX. 51 */ 52 personality |= PER_LINUX; 53 54 /* 55 * APCS-26 is only valid for OABI executables 56 */ 57 if ((eflags & EF_ARM_EABI_MASK) == EF_ARM_EABI_UNKNOWN && 58 (eflags & EF_ARM_APCS_26)) 59 personality &= ~ADDR_LIMIT_32BIT; 60 else 61 personality |= ADDR_LIMIT_32BIT; 62 63 set_personality(personality); 64 65 /* 66 * Since the FPA coprocessor uses CP1 and CP2, and iWMMXt uses CP0 67 * and CP1, we only enable access to the iWMMXt coprocessor if the 68 * binary is EABI or softfloat (and thus, guaranteed not to use 69 * FPA instructions.) 70 */ 71 if (elf_hwcap & HWCAP_IWMMXT && 72 eflags & (EF_ARM_EABI_MASK | EF_ARM_SOFT_FLOAT)) { 73 set_thread_flag(TIF_USING_IWMMXT); 74 } else { 75 clear_thread_flag(TIF_USING_IWMMXT); 76 } 77 } 78 EXPORT_SYMBOL(elf_set_personality); 79 80 /* 81 * Set READ_IMPLIES_EXEC if: 82 * - the binary requires an executable stack 83 * - we're running on a CPU which doesn't support NX. 84 */ 85 int arm_elf_read_implies_exec(int executable_stack) 86 { 87 if (executable_stack != EXSTACK_DISABLE_X) 88 return 1; 89 if (cpu_architecture() < CPU_ARCH_ARMv6) 90 return 1; 91 return 0; 92 } 93 EXPORT_SYMBOL(arm_elf_read_implies_exec); 94 95 #if defined(CONFIG_MMU) && defined(CONFIG_BINFMT_ELF_FDPIC) 96 97 void elf_fdpic_arch_lay_out_mm(struct elf_fdpic_params *exec_params, 98 struct elf_fdpic_params *interp_params, 99 unsigned long *start_stack, 100 unsigned long *start_brk) 101 { 102 elf_set_personality(&exec_params->hdr); 103 104 exec_params->load_addr = 0x8000; 105 interp_params->load_addr = ELF_ET_DYN_BASE; 106 *start_stack = TASK_SIZE - SZ_16M; 107 108 if ((exec_params->flags & ELF_FDPIC_FLAG_ARRANGEMENT) == ELF_FDPIC_FLAG_INDEPENDENT) { 109 exec_params->flags &= ~ELF_FDPIC_FLAG_ARRANGEMENT; 110 exec_params->flags |= ELF_FDPIC_FLAG_CONSTDISP; 111 } 112 } 113 114 #endif 115