1 // SPDX-License-Identifier: GPL-2.0
3 * arch/sh/kernel/vsyscall/vsyscall.c
5 * Copyright (C) 2006 Paul Mundt
8 * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar
11 #include <linux/kernel.h>
12 #include <linux/init.h>
13 #include <linux/gfp.h>
14 #include <linux/module.h>
15 #include <linux/elf.h>
16 #include <linux/sched.h>
17 #include <linux/err.h>
20 * Should the kernel map a VDSO page into processes and pass its
21 * address down to glibc upon exec()?
23 unsigned int __read_mostly vdso_enabled = 1;
24 EXPORT_SYMBOL_GPL(vdso_enabled);
26 static int __init vdso_setup(char *s)
28 vdso_enabled = simple_strtoul(s, NULL, 0);
31 __setup("vdso=", vdso_setup);
34 * These symbols are defined by vsyscall.o to mark the bounds
35 * of the ELF DSO images included therein.
37 extern const char vsyscall_trapa_start, vsyscall_trapa_end;
38 static struct page *syscall_pages[1];
40 int __init vsyscall_init(void)
42 void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
43 syscall_pages[0] = virt_to_page(syscall_page);
46 * XXX: Map this page to a fixmap entry if we get around
47 * to adding the page to ELF core dumps
51 &vsyscall_trapa_start,
52 &vsyscall_trapa_end - &vsyscall_trapa_start);
57 /* Setup a VMA at program startup for the vsyscall page */
58 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
60 struct mm_struct *mm = current->mm;
64 if (mmap_write_lock_killable(mm))
67 addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
68 if (IS_ERR_VALUE(addr)) {
73 ret = install_special_mapping(mm, addr, PAGE_SIZE,
75 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
80 current->mm->context.vdso = (void *)addr;
83 mmap_write_unlock(mm);
87 const char *arch_vma_name(struct vm_area_struct *vma)
89 if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)