* linux/arch/i386/kernel/sysenter.c
*
* (C) Copyright 2002 Linus Torvalds
- * Portions based on the vdso-randomization code from exec-shield:
- * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar
*
* This file contains the needed initializations to support sysenter.
*/
#include <linux/elf.h>
#include <linux/mm.h>
#include <linux/mman.h>
-#include <linux/module.h>
-#include <linux/vs_base.h>
-#include <linux/vs_memory.h>
+#include <asm/a.out.h>
#include <asm/cpufeature.h>
#include <asm/msr.h>
#include <asm/pgtable.h>
#include <xen/interface/callback.h>
#endif
-/*
- * 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);
-
extern asmlinkage void sysenter_entry(void);
void enable_sep_cpu(void)
*/
extern const char vsyscall_int80_start, vsyscall_int80_end;
extern const char vsyscall_sysenter_start, vsyscall_sysenter_end;
-static void *syscall_page;
+static struct page *sysenter_pages[2];
int __init sysenter_setup(void)
{
- syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
+ void *page = (void *)get_zeroed_page(GFP_ATOMIC);
+
+ sysenter_pages[0] = virt_to_page(page);
#ifdef CONFIG_XEN
if (boot_cpu_has(X86_FEATURE_SEP)) {
}
#endif
-#ifdef CONFIG_COMPAT_VDSO
- __set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_READONLY);
- printk("Compat vDSO mapped to %08lx.\n", __fix_to_virt(FIX_VDSO));
-#else
- /*
- * In the non-compat case the ELF coredumping code needs the fixmap:
- */
-#ifdef CONFIG_XEN
- __set_fixmap(FIX_VDSO, virt_to_machine(syscall_page), PAGE_KERNEL_RO);
-#else
- __set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_KERNEL_RO);
-#endif
-#endif
-
- if (!boot_cpu_has(X86_FEATURE_SEP)) {
- memcpy(syscall_page,
- &vsyscall_int80_start,
- &vsyscall_int80_end - &vsyscall_int80_start);
+ if (boot_cpu_has(X86_FEATURE_SEP)) {
+ memcpy(page,
+ &vsyscall_sysenter_start,
+ &vsyscall_sysenter_end - &vsyscall_sysenter_start);
return 0;
}
- memcpy(syscall_page,
- &vsyscall_sysenter_start,
- &vsyscall_sysenter_end - &vsyscall_sysenter_start);
+ memcpy(page,
+ &vsyscall_int80_start,
+ &vsyscall_int80_end - &vsyscall_int80_start);
return 0;
}
-static struct page *syscall_nopage(struct vm_area_struct *vma,
- unsigned long adr, int *type)
-{
- struct page *p = virt_to_page(adr - vma->vm_start + syscall_page);
- get_page(p);
- return p;
-}
+extern void SYSENTER_RETURN_OFFSET;
-/* Prevent VMA merging */
-static void syscall_vma_close(struct vm_area_struct *vma)
-{
-}
+unsigned int vdso_enabled = 1;
-static struct vm_operations_struct syscall_vm_ops = {
- .close = syscall_vma_close,
- .nopage = syscall_nopage,
-};
+/*
+ * This is called from binfmt_elf, we create the special vma for the
+ * vDSO and insert it into the mm struct tree.
+ */
+int arch_setup_additional_pages(struct linux_binprm *bprm,
+ int executable_stack, unsigned long start_code,
+ unsigned long interp_map_address)
+{
+ struct thread_info *ti = current_thread_info();
+ unsigned long addr = 0, len;
+ unsigned flags = MAP_PRIVATE;
+ int err;
-/* Defined in vsyscall-sysenter.S */
-extern void SYSENTER_RETURN;
+ current->mm->context.vdso = NULL;
+ if (unlikely(!vdso_enabled) || unlikely(!sysenter_pages[0]))
+ return 0;
-/* Setup a VMA at program startup for the vsyscall page */
-int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack,
- unsigned long start_code, unsigned long interp_map_address)
-{
- struct vm_area_struct *vma;
- struct mm_struct *mm = current->mm;
- unsigned long addr;
- int ret;
-
- down_write(&mm->mmap_sem);
- addr = get_unmapped_area_prot(NULL, 0, PAGE_SIZE, 0, 0, 1);
- if (IS_ERR_VALUE(addr)) {
- ret = addr;
- goto up_fail;
+ /*
+ * Map the vDSO (it will be randomized):
+ */
+ down_write(¤t->mm->mmap_sem);
+ len = PAGE_SIZE > ELF_EXEC_PAGESIZE ? PAGE_SIZE : ELF_EXEC_PAGESIZE;
+ if (0==exec_shield) { /* off; %cs limit off */
+ addr = STACK_TOP; /* minimal interference with anybody */
+ flags = MAP_PRIVATE | MAP_FIXED;
}
-
- vma = kmem_cache_zalloc(vm_area_cachep, SLAB_KERNEL);
- if (!vma) {
- ret = -ENOMEM;
- goto up_fail;
+ else if ((3<<2) & exec_shield) { /* vdso just below .text */
+ addr = (((2<<2) & exec_shield) && interp_map_address) ?
+ interp_map_address : start_code;
+ /* 1MB for vm86; 64K for vm86 himem */
+ if ((0x110000 + len) <= addr) {
+ addr = (PAGE_MASK & addr) - len;
+ }
+ else { /* start_code is too low */
+ addr = 0;
+ }
}
-
- vma->vm_start = addr;
- vma->vm_end = addr + PAGE_SIZE;
- /* MAYWRITE to allow gdb to COW and set breakpoints */
- vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC|VM_MAYWRITE;
- vma->vm_flags |= mm->def_flags;
- vma->vm_page_prot = protection_map[vma->vm_flags & 7];
- vma->vm_ops = &syscall_vm_ops;
- vma->vm_mm = mm;
-
- ret = insert_vm_struct(mm, vma);
- if (unlikely(ret)) {
- kmem_cache_free(vm_area_cachep, vma);
- goto up_fail;
+ addr = get_unmapped_area_prot(NULL, addr, len, 0,
+ flags, PROT_READ | PROT_EXEC);
+ if (unlikely(addr & ~PAGE_MASK)) {
+ up_write(¤t->mm->mmap_sem);
+ return addr;
}
-
- current->mm->context.vdso = (void *)addr;
- current_thread_info()->sysenter_return =
- (void *)VDSO_SYM(&SYSENTER_RETURN);
- vx_vmpages_inc(mm);
-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;
+ err = install_special_mapping(current->mm, addr, len,
+ VM_DONTEXPAND | VM_READ | VM_EXEC |
+ VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
+ PAGE_READONLY_EXEC,
+ sysenter_pages);
+ if (likely(err == 0)) {
+ current->mm->context.vdso = (void *)addr;
+ ti->sysenter_return = &SYSENTER_RETURN_OFFSET + addr;
+ }
+ up_write(¤t->mm->mmap_sem);
+ return err;
}
-struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
+#ifndef CONFIG_XEN
+int in_gate_area_no_task(unsigned long addr)
{
- return NULL;
+ return 0;
}
int in_gate_area(struct task_struct *task, unsigned long addr)
return 0;
}
-int in_gate_area_no_task(unsigned long addr)
+struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
{
- return 0;
+ return NULL;
}
+#endif
git://git.onelab.eu / linux-2.6.git / blobdiff