i386: NX emulation

[linux-flexiantxendom0-natty.git] / arch / x86 / kernel / process_32.c

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 8d12878..fde71df 100644 (file)
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -243,7 +243,10 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
 void
 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
 {
+       int cpu;
+
        set_user_gs(regs, 0);
+
        regs->fs                = 0;
        set_fs(USER_DS);
        regs->ds                = __USER_DS;
@@ -252,6 +255,11 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
        regs->cs                = __USER_CS;
        regs->ip                = new_ip;
        regs->sp                = new_sp;
+
+       cpu = get_cpu();
+       load_user_cs_desc(cpu, current->mm);
+       put_cpu();
+
        /*
         * Free the old FP and other extended state
         */
@@ -311,6 +319,9 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
        if (preload_fpu)
                prefetch(next->fpu.state);
 
+       if (next_p->mm)
+               load_user_cs_desc(cpu, next_p->mm);
+
        /*
         * Reload esp0.
         */
@@ -404,3 +415,40 @@ unsigned long get_wchan(struct task_struct *p)
        return 0;
 }
 
+static void modify_cs(struct mm_struct *mm, unsigned long limit)
+{
+       mm->context.exec_limit = limit;
+       set_user_cs(&mm->context.user_cs, limit);
+       if (mm == current->mm) {
+               int cpu;
+
+               cpu = get_cpu();
+               load_user_cs_desc(cpu, mm);
+               put_cpu();
+       }
+}
+
+void arch_add_exec_range(struct mm_struct *mm, unsigned long limit)
+{
+       if (limit > mm->context.exec_limit)
+               modify_cs(mm, limit);
+}
+
+void arch_remove_exec_range(struct mm_struct *mm, unsigned long old_end)
+{
+       struct vm_area_struct *vma;
+       unsigned long limit = PAGE_SIZE;
+
+       if (old_end == mm->context.exec_limit) {
+               for (vma = mm->mmap; vma; vma = vma->vm_next)
+                       if ((vma->vm_flags & VM_EXEC) && (vma->vm_end > limit))
+                               limit = vma->vm_end;
+               modify_cs(mm, limit);
+       }
+}
+
+void arch_flush_exec_range(struct mm_struct *mm)
+{
+       mm->context.exec_limit = 0;
+       set_user_cs(&mm->context.user_cs, 0);
+}