* 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/string.h>
#include <linux/elf.h>
#include <linux/mm.h>
-#include <linux/mman.h>
+#include <linux/module.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 struct page *sysenter_pages[2];
+static void *syscall_page;
int __init sysenter_setup(void)
{
- void *page = (void *)get_zeroed_page(GFP_ATOMIC);
-
- sysenter_pages[0] = virt_to_page(page);
+ syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
#ifdef CONFIG_XEN
if (boot_cpu_has(X86_FEATURE_SEP)) {
}
#endif
- if (boot_cpu_has(X86_FEATURE_SEP)) {
- memcpy(page,
- &vsyscall_sysenter_start,
- &vsyscall_sysenter_end - &vsyscall_sysenter_start);
+#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);
return 0;
}
- memcpy(page,
- &vsyscall_int80_start,
- &vsyscall_int80_end - &vsyscall_int80_start);
+ memcpy(syscall_page,
+ &vsyscall_sysenter_start,
+ &vsyscall_sysenter_end - &vsyscall_sysenter_start);
return 0;
}
-extern void SYSENTER_RETURN_OFFSET;
-
-unsigned int vdso_enabled = 1;
+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;
+}
-/*
- * 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)
+/* Prevent VMA merging */
+static void syscall_vma_close(struct vm_area_struct *vma)
{
- struct thread_info *ti = current_thread_info();
- unsigned long addr = 0, len;
- unsigned flags = MAP_PRIVATE;
- int err;
+}
- current->mm->context.vdso = NULL;
- if (unlikely(!vdso_enabled) || unlikely(!sysenter_pages[0]))
- return 0;
+static struct vm_operations_struct syscall_vm_ops = {
+ .close = syscall_vma_close,
+ .nopage = syscall_nopage,
+};
- /*
- * 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;
- }
- 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;
- }
+/* Defined in vsyscall-sysenter.S */
+extern void SYSENTER_RETURN;
+
+/* 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;
}
- 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;
+
+ vma = kmem_cache_zalloc(vm_area_cachep, SLAB_KERNEL);
+ if (!vma) {
+ ret = -ENOMEM;
+ goto up_fail;
}
- 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;
+
+ 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;
}
- up_write(¤t->mm->mmap_sem);
- return err;
+
+ 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;
}
-#ifndef CONFIG_XEN
-int in_gate_area_no_task(unsigned long addr)
+const char *arch_vma_name(struct vm_area_struct *vma)
{
- return 0;
+ 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 *tsk)
+{
+ return NULL;
}
int in_gate_area(struct task_struct *task, unsigned long addr)
return 0;
}
-struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
+int in_gate_area_no_task(unsigned long addr)
{
- return NULL;
+ return 0;
}
-#endif
git://git.onelab.eu / linux-2.6.git / blobdiff