134 lines
3.8 KiB
C
134 lines
3.8 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/export.h>
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#include <linux/sched.h>
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#include <linux/personality.h>
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#include <linux/binfmts.h>
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#include <linux/elf.h>
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#include <linux/elf-fdpic.h>
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#include <asm/system_info.h>
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int elf_check_arch(const struct elf32_hdr *x)
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{
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unsigned int eflags;
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/* Make sure it's an ARM executable */
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if (x->e_machine != EM_ARM)
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return 0;
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/* Make sure the entry address is reasonable */
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if (x->e_entry & 1) {
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if (!(elf_hwcap & HWCAP_THUMB))
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return 0;
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} else if (x->e_entry & 3)
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return 0;
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eflags = x->e_flags;
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if ((eflags & EF_ARM_EABI_MASK) == EF_ARM_EABI_UNKNOWN) {
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unsigned int flt_fmt;
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/* APCS26 is only allowed if the CPU supports it */
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if ((eflags & EF_ARM_APCS_26) && !(elf_hwcap & HWCAP_26BIT))
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return 0;
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flt_fmt = eflags & (EF_ARM_VFP_FLOAT | EF_ARM_SOFT_FLOAT);
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/* VFP requires the supporting code */
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if (flt_fmt == EF_ARM_VFP_FLOAT && !(elf_hwcap & HWCAP_VFP))
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return 0;
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}
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return 1;
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}
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EXPORT_SYMBOL(elf_check_arch);
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void elf_set_personality(const struct elf32_hdr *x)
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{
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unsigned int eflags = x->e_flags;
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unsigned int personality = current->personality & ~PER_MASK;
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/*
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* We only support Linux ELF executables, so always set the
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* personality to LINUX.
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*/
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personality |= PER_LINUX;
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/*
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* APCS-26 is only valid for OABI executables
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*/
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if ((eflags & EF_ARM_EABI_MASK) == EF_ARM_EABI_UNKNOWN &&
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(eflags & EF_ARM_APCS_26))
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personality &= ~ADDR_LIMIT_32BIT;
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else
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personality |= ADDR_LIMIT_32BIT;
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set_personality(personality);
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/*
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* Since the FPA coprocessor uses CP1 and CP2, and iWMMXt uses CP0
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* and CP1, we only enable access to the iWMMXt coprocessor if the
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* binary is EABI or softfloat (and thus, guaranteed not to use
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* FPA instructions.)
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*/
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if (elf_hwcap & HWCAP_IWMMXT &&
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eflags & (EF_ARM_EABI_MASK | EF_ARM_SOFT_FLOAT)) {
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set_thread_flag(TIF_USING_IWMMXT);
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} else {
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clear_thread_flag(TIF_USING_IWMMXT);
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}
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}
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EXPORT_SYMBOL(elf_set_personality);
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/*
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* An executable for which elf_read_implies_exec() returns TRUE will
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* have the READ_IMPLIES_EXEC personality flag set automatically.
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*
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* The decision process for determining the results are:
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*
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* CPU: | lacks NX* | has NX |
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* ELF: | | |
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* ---------------------|------------|------------|
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* missing PT_GNU_STACK | exec-all | exec-all |
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* PT_GNU_STACK == RWX | exec-all | exec-stack |
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* PT_GNU_STACK == RW | exec-all | exec-none |
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*
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* exec-all : all PROT_READ user mappings are executable, except when
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* backed by files on a noexec-filesystem.
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* exec-none : only PROT_EXEC user mappings are executable.
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* exec-stack: only the stack and PROT_EXEC user mappings are executable.
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*
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* *this column has no architectural effect: NX markings are ignored by
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* hardware, but may have behavioral effects when "wants X" collides with
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* "cannot be X" constraints in memory permission flags, as in
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* https://lkml.kernel.org/r/20190418055759.GA3155@mellanox.com
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*
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*/
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int arm_elf_read_implies_exec(int executable_stack)
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{
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if (executable_stack == EXSTACK_DEFAULT)
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return 1;
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if (cpu_architecture() < CPU_ARCH_ARMv6)
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return 1;
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return 0;
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}
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EXPORT_SYMBOL(arm_elf_read_implies_exec);
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#if defined(CONFIG_MMU) && defined(CONFIG_BINFMT_ELF_FDPIC)
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void elf_fdpic_arch_lay_out_mm(struct elf_fdpic_params *exec_params,
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struct elf_fdpic_params *interp_params,
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unsigned long *start_stack,
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unsigned long *start_brk)
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{
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elf_set_personality(&exec_params->hdr);
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exec_params->load_addr = 0x8000;
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interp_params->load_addr = ELF_ET_DYN_BASE;
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*start_stack = TASK_SIZE - SZ_16M;
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if ((exec_params->flags & ELF_FDPIC_FLAG_ARRANGEMENT) == ELF_FDPIC_FLAG_INDEPENDENT) {
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exec_params->flags &= ~ELF_FDPIC_FLAG_ARRANGEMENT;
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exec_params->flags |= ELF_FDPIC_FLAG_CONSTDISP;
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}
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}
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#endif
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