| /* |
| * arch/sh/kernel/vsyscall/vsyscall.c |
| * |
| * Copyright (C) 2006 Paul Mundt |
| * |
| * vDSO randomization |
| * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar |
| * |
| * This file is subject to the terms and conditions of the GNU General Public |
| * License. See the file "COPYING" in the main directory of this archive |
| * for more details. |
| */ |
| #include <linux/mm.h> |
| #include <linux/slab.h> |
| #include <linux/kernel.h> |
| #include <linux/init.h> |
| #include <linux/gfp.h> |
| #include <linux/module.h> |
| #include <linux/elf.h> |
| |
| /* |
| * Should the kernel map a VDSO page into processes and pass its |
| * address down to glibc upon exec()? |
| */ |
| unsigned int __read_mostly vdso_enabled = 1; |
| EXPORT_SYMBOL_GPL(vdso_enabled); |
| |
| static int __init vdso_setup(char *s) |
| { |
| vdso_enabled = simple_strtoul(s, NULL, 0); |
| return 1; |
| } |
| __setup("vdso=", vdso_setup); |
| |
| /* |
| * These symbols are defined by vsyscall.o to mark the bounds |
| * of the ELF DSO images included therein. |
| */ |
| extern const char vsyscall_trapa_start, vsyscall_trapa_end; |
| static struct page *syscall_pages[1]; |
| |
| int __init vsyscall_init(void) |
| { |
| void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC); |
| syscall_pages[0] = virt_to_page(syscall_page); |
| |
| /* |
| * XXX: Map this page to a fixmap entry if we get around |
| * to adding the page to ELF core dumps |
| */ |
| |
| memcpy(syscall_page, |
| &vsyscall_trapa_start, |
| &vsyscall_trapa_end - &vsyscall_trapa_start); |
| |
| return 0; |
| } |
| |
| /* Setup a VMA at program startup for the vsyscall page */ |
| int arch_setup_additional_pages(struct linux_binprm *bprm, |
| int executable_stack) |
| { |
| struct mm_struct *mm = current->mm; |
| unsigned long addr; |
| int ret; |
| |
| down_write(&mm->mmap_sem); |
| addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); |
| if (IS_ERR_VALUE(addr)) { |
| ret = addr; |
| goto up_fail; |
| } |
| |
| ret = install_special_mapping(mm, addr, PAGE_SIZE, |
| VM_READ | VM_EXEC | |
| VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC | |
| VM_ALWAYSDUMP, |
| syscall_pages); |
| if (unlikely(ret)) |
| goto up_fail; |
| |
| current->mm->context.vdso = (void *)addr; |
| |
| up_fail: |
| up_write(&mm->mmap_sem); |
| 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; |
| } |
| |
| struct vm_area_struct *get_gate_vma(struct task_struct *task) |
| { |
| return NULL; |
| } |
| |
| int in_gate_area(struct task_struct *task, unsigned long address) |
| { |
| return 0; |
| } |
| |
| int in_gate_area_no_task(unsigned long address) |
| { |
| return 0; |
| } |