LXR linux/arch/arm/kernel/elf.c

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