Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/shaggy...

[pandora-kernel.git] / arch / i386 / kernel / sysenter.c

diff --git a/arch/i386/kernel/sysenter.c b/arch/i386/kernel/sysenter.c
index 0bada18..7de9117 100644 (file)
--- a/arch/i386/kernel/sysenter.c
+++ b/arch/i386/kernel/sysenter.c
@@ -2,6 +2,8 @@
  * 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.
  */
@@ -13,12 +15,35 @@
 #include <linux/gfp.h>
 #include <linux/string.h>
 #include <linux/elf.h>
+#include <linux/mm.h>
+#include <linux/module.h>
 
 #include <asm/cpufeature.h>
 #include <asm/msr.h>
 #include <asm/pgtable.h>
 #include <asm/unistd.h>
 
+/*
+ * Should the kernel map a VDSO page into processes and pass its
+ * address down to glibc upon exec()?
+ */
+#ifdef CONFIG_PARAVIRT
+unsigned int __read_mostly vdso_enabled = 0;
+#else
+unsigned int __read_mostly vdso_enabled = 1;
+#endif
+
+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)
@@ -45,23 +70,120 @@ 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;
 
 int __init sysenter_setup(void)
 {
-       void *page = (void *)get_zeroed_page(GFP_ATOMIC);
+       syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
 
-       __set_fixmap(FIX_VSYSCALL, __pa(page), PAGE_READONLY_EXEC);
+#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:
+        */
+       __set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_KERNEL_RO);
+#endif
 
        if (!boot_cpu_has(X86_FEATURE_SEP)) {
-               memcpy(page,
+               memcpy(syscall_page,
                       &vsyscall_int80_start,
                       &vsyscall_int80_end - &vsyscall_int80_start);
                return 0;
        }
 
-       memcpy(page,
+       memcpy(syscall_page,
               &vsyscall_sysenter_start,
               &vsyscall_sysenter_end - &vsyscall_sysenter_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;
+}
+
+/* Prevent VMA merging */
+static void syscall_vma_close(struct vm_area_struct *vma)
+{
+}
+
+static struct vm_operations_struct syscall_vm_ops = {
+       .close = syscall_vma_close,
+       .nopage = syscall_nopage,
+};
+
+/* 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)
+{
+       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(NULL, 0, PAGE_SIZE, 0, 0);
+       if (IS_ERR_VALUE(addr)) {
+               ret = addr;
+               goto up_fail;
+       }
+
+       vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+       if (!vma) {
+               ret = -ENOMEM;
+               goto up_fail;
+       }
+
+       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;
+       }
+
+       current->mm->context.vdso = (void *)addr;
+       current_thread_info()->sysenter_return =
+                                   (void *)VDSO_SYM(&SYSENTER_RETURN);
+       mm->total_vm++;
+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 *tsk)
+{
+       return NULL;
+}
+
+int in_gate_area(struct task_struct *task, unsigned long addr)
+{
+       return 0;
+}
+
+int in_gate_area_no_task(unsigned long addr)
+{
+       return 0;
+}