1 files changed, 88 insertions, 0 deletions
diff --git a/arch/hexagon/kernel/vdso.c b/arch/hexagon/kernel/vdso.c
new file mode 100644
index 0000000000..b70970ac80
--- /dev/null
+++ b/arch/hexagon/kernel/vdso.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * vDSO implementation for Hexagon
+ *
+ * Copyright (c) 2011, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/err.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/binfmts.h>
+
+#include <asm/vdso.h>
+
+static struct page *vdso_page;
+
+/* Create a vDSO page holding the signal trampoline.
+ * We want this for a non-executable stack.
+ */
+static int __init vdso_init(void)
+{
+	struct hexagon_vdso *vdso;
+
+	vdso_page = alloc_page(GFP_KERNEL);
+	if (!vdso_page)
+		panic("Cannot allocate vdso");
+
+	vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL);
+	if (!vdso)
+		panic("Cannot map vdso");
+	clear_page(vdso);
+
+	/* Install the signal trampoline; currently looks like this:
+	 *	r6 = #__NR_rt_sigreturn;
+	 *	trap0(#1);
+	 */
+	vdso->rt_signal_trampoline[0] = __rt_sigtramp_template[0];
+	vdso->rt_signal_trampoline[1] = __rt_sigtramp_template[1];
+
+	vunmap(vdso);
+
+	return 0;
+}
+arch_initcall(vdso_init);
+
+/*
+ * Called from binfmt_elf.  Create a VMA for the vDSO page.
+ */
+int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+{
+	int ret;
+	unsigned long vdso_base;
+	struct mm_struct *mm = current->mm;
+
+	if (mmap_write_lock_killable(mm))
+		return -EINTR;
+
+	/* Try to get it loaded right near ld.so/glibc. */
+	vdso_base = STACK_TOP;
+
+	vdso_base = get_unmapped_area(NULL, vdso_base, PAGE_SIZE, 0, 0);
+	if (IS_ERR_VALUE(vdso_base)) {
+		ret = vdso_base;
+		goto up_fail;
+	}
+
+	/* MAYWRITE to allow gdb to COW and set breakpoints. */
+	ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
+				      VM_READ|VM_EXEC|
+				      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
+				      &vdso_page);
+
+	if (ret)
+		goto up_fail;
+
+	mm->context.vdso = (void *)vdso_base;
+
+up_fail:
+	mmap_write_unlock(mm);
+	return ret;
+}
+
+const char *arch_vma_name(struct vm_area_struct *vma)
+{
+	if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
+		return "[vdso]";
+	return NULL;
+}