x86: x86-64 ia32 ptrace get/putreg32 current task

This generalizes the getreg32 and putreg32 functions so they can be used on
the current task, as well as on a task stopped in TASK_TRACED and switched
off.  This lays the groundwork to share this code for all kinds of
user-mode machine state access, not just ptrace.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/ia32/ptrace32.c

@@ -48,19 +48,27 @@ static int putreg32(struct task_struct *child, unsigned regno, u32 val)
 		if (val && (val & 3) != 3)
 			return -EIO;
 		child->thread.fsindex = val & 0xffff;
+		if (child == current)
+			loadsegment(fs, child->thread.fsindex);
 		break;
 	case offsetof(struct user32, regs.gs):
 		if (val && (val & 3) != 3)
 			return -EIO;
 		child->thread.gsindex = val & 0xffff;
+		if (child == current)
+			load_gs_index(child->thread.gsindex);
 		break;
 	case offsetof(struct user32, regs.ds):
 		if (val && (val & 3) != 3)
 			return -EIO;
 		child->thread.ds = val & 0xffff;
+		if (child == current)
+			loadsegment(ds, child->thread.ds);
 		break;
 	case offsetof(struct user32, regs.es):
 		child->thread.es = val & 0xffff;
+		if (child == current)
+			loadsegment(es, child->thread.ds);
 		break;
 	case offsetof(struct user32, regs.ss):
 		if ((val & 3) != 3)
@@ -129,15 +137,23 @@ static int getreg32(struct task_struct *child, unsigned regno, u32 *val)
 	switch (regno) {
 	case offsetof(struct user32, regs.fs):
 		*val = child->thread.fsindex;
+		if (child == current)
+			asm("movl %%fs,%0" : "=r" (*val));
 		break;
 	case offsetof(struct user32, regs.gs):
 		*val = child->thread.gsindex;
+		if (child == current)
+			asm("movl %%gs,%0" : "=r" (*val));
 		break;
 	case offsetof(struct user32, regs.ds):
 		*val = child->thread.ds;
+		if (child == current)
+			asm("movl %%ds,%0" : "=r" (*val));
 		break;
 	case offsetof(struct user32, regs.es):
 		*val = child->thread.es;
+		if (child == current)
+			asm("movl %%es,%0" : "=r" (*val));
 		break;
 
 	R32(cs, cs);