diff options
Diffstat (limited to 'kernel/arch/sh/kernel/vsyscall/vsyscall.c')
-rw-r--r-- | kernel/arch/sh/kernel/vsyscall/vsyscall.c | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/kernel/arch/sh/kernel/vsyscall/vsyscall.c b/kernel/arch/sh/kernel/vsyscall/vsyscall.c new file mode 100644 index 000000000..ea2aa1393 --- /dev/null +++ b/kernel/arch/sh/kernel/vsyscall/vsyscall.c @@ -0,0 +1,94 @@ +/* + * 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/kernel.h> +#include <linux/init.h> +#include <linux/gfp.h> +#include <linux/module.h> +#include <linux/elf.h> +#include <linux/sched.h> +#include <linux/err.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 uses_interp) +{ + 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, + 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; +} |