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-rw-r--r--arch/arm/kernel/elf.c133
1 files changed, 133 insertions, 0 deletions
diff --git a/arch/arm/kernel/elf.c b/arch/arm/kernel/elf.c
new file mode 100644
index 0000000000..254ab7138c
--- /dev/null
+++ b/arch/arm/kernel/elf.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/personality.h>
+#include <linux/binfmts.h>
+#include <linux/elf.h>
+#include <linux/elf-fdpic.h>
+#include <asm/system_info.h>
+
+int elf_check_arch(const struct elf32_hdr *x)
+{
+ unsigned int eflags;
+
+ /* Make sure it's an ARM executable */
+ if (x->e_machine != EM_ARM)
+ return 0;
+
+ /* Make sure the entry address is reasonable */
+ if (x->e_entry & 1) {
+ if (!(elf_hwcap & HWCAP_THUMB))
+ return 0;
+ } else if (x->e_entry & 3)
+ return 0;
+
+ eflags = x->e_flags;
+ if ((eflags & EF_ARM_EABI_MASK) == EF_ARM_EABI_UNKNOWN) {
+ unsigned int flt_fmt;
+
+ /* APCS26 is only allowed if the CPU supports it */
+ if ((eflags & EF_ARM_APCS_26) && !(elf_hwcap & HWCAP_26BIT))
+ return 0;
+
+ flt_fmt = eflags & (EF_ARM_VFP_FLOAT | EF_ARM_SOFT_FLOAT);
+
+ /* VFP requires the supporting code */
+ if (flt_fmt == EF_ARM_VFP_FLOAT && !(elf_hwcap & HWCAP_VFP))
+ return 0;
+ }
+ return 1;
+}
+EXPORT_SYMBOL(elf_check_arch);
+
+void elf_set_personality(const struct elf32_hdr *x)
+{
+ unsigned int eflags = x->e_flags;
+ unsigned int personality = current->personality & ~PER_MASK;
+
+ /*
+ * We only support Linux ELF executables, so always set the
+ * personality to LINUX.
+ */
+ personality |= PER_LINUX;
+
+ /*
+ * APCS-26 is only valid for OABI executables
+ */
+ if ((eflags & EF_ARM_EABI_MASK) == EF_ARM_EABI_UNKNOWN &&
+ (eflags & EF_ARM_APCS_26))
+ personality &= ~ADDR_LIMIT_32BIT;
+ else
+ personality |= ADDR_LIMIT_32BIT;
+
+ set_personality(personality);
+
+ /*
+ * Since the FPA coprocessor uses CP1 and CP2, and iWMMXt uses CP0
+ * and CP1, we only enable access to the iWMMXt coprocessor if the
+ * binary is EABI or softfloat (and thus, guaranteed not to use
+ * FPA instructions.)
+ */
+ if (elf_hwcap & HWCAP_IWMMXT &&
+ eflags & (EF_ARM_EABI_MASK | EF_ARM_SOFT_FLOAT)) {
+ set_thread_flag(TIF_USING_IWMMXT);
+ } else {
+ clear_thread_flag(TIF_USING_IWMMXT);
+ }
+}
+EXPORT_SYMBOL(elf_set_personality);
+
+/*
+ * An executable for which elf_read_implies_exec() returns TRUE will
+ * have the READ_IMPLIES_EXEC personality flag set automatically.
+ *
+ * The decision process for determining the results are:
+ *
+ *              CPU: | lacks NX*  | has NX |
+ * ELF:              |            |           |
+ * ---------------------|------------|------------|
+ * missing PT_GNU_STACK | exec-all   | exec-all  |
+ * PT_GNU_STACK == RWX  | exec-all   | exec-stack |
+ * PT_GNU_STACK == RW   | exec-all  | exec-none |
+ *
+ * exec-all : all PROT_READ user mappings are executable, except when
+ * backed by files on a noexec-filesystem.
+ * exec-none : only PROT_EXEC user mappings are executable.
+ * exec-stack: only the stack and PROT_EXEC user mappings are executable.
+ *
+ * *this column has no architectural effect: NX markings are ignored by
+ * hardware, but may have behavioral effects when "wants X" collides with
+ * "cannot be X" constraints in memory permission flags, as in
+ * https://lkml.kernel.org/r/20190418055759.GA3155@mellanox.com
+ *
+ */
+int arm_elf_read_implies_exec(int executable_stack)
+{
+ if (executable_stack == EXSTACK_DEFAULT)
+ return 1;
+ if (cpu_architecture() < CPU_ARCH_ARMv6)
+ return 1;
+ return 0;
+}
+EXPORT_SYMBOL(arm_elf_read_implies_exec);
+
+#if defined(CONFIG_MMU) && defined(CONFIG_BINFMT_ELF_FDPIC)
+
+void elf_fdpic_arch_lay_out_mm(struct elf_fdpic_params *exec_params,
+ struct elf_fdpic_params *interp_params,
+ unsigned long *start_stack,
+ unsigned long *start_brk)
+{
+ elf_set_personality(&exec_params->hdr);
+
+ exec_params->load_addr = 0x8000;
+ interp_params->load_addr = ELF_ET_DYN_BASE;
+ *start_stack = TASK_SIZE - SZ_16M;
+
+ if ((exec_params->flags & ELF_FDPIC_FLAG_ARRANGEMENT) == ELF_FDPIC_FLAG_INDEPENDENT) {
+ exec_params->flags &= ~ELF_FDPIC_FLAG_ARRANGEMENT;
+ exec_params->flags |= ELF_FDPIC_FLAG_CONSTDISP;
+ }
+}
+
+#endif