[PATCH] x86_64: fix 32-bit thread debugging

The IA32 ptrace emulation currently returns the wrong registers for fs/gs;
it's returning what x86_64 calls gs_base.  We need regs.gsindex in order
for GDB to correctly locate the TLS area.  Without this patch, the 32-bit
GDB testsuite bombs on a 64-bit kernel.  With it, results look about like
I'd expect, although there are still a handful of kernel-related failures
(vsyscall related?).

Signed-off-by: Daniel Jacobowitz <dan@codesourcery.com>
Acked-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/x86_64/ia32/ptrace32.c

@@ -43,11 +43,11 @@ static int putreg32(struct task_struct *child, unsigned regno, u32 val)
 	switch (regno) {
 	case offsetof(struct user32, regs.fs):
 		if (val && (val & 3) != 3) return -EIO; 
-		child->thread.fs = val & 0xffff; 
+		child->thread.fsindex = val & 0xffff;
 		break;
 	case offsetof(struct user32, regs.gs):
 		if (val && (val & 3) != 3) return -EIO; 
-		child->thread.gs = val & 0xffff;
+		child->thread.gsindex = val & 0xffff;
 		break;
 	case offsetof(struct user32, regs.ds):
 		if (val && (val & 3) != 3) return -EIO; 
@@ -138,10 +138,10 @@ static int getreg32(struct task_struct *child, unsigned regno, u32 *val)
 
 	switch (regno) {
 	case offsetof(struct user32, regs.fs):
-	        *val = child->thread.fs; 
+	        *val = child->thread.fsindex;
 		break;
 	case offsetof(struct user32, regs.gs):
-		*val = child->thread.gs;
+		*val = child->thread.gsindex;
 		break;
 	case offsetof(struct user32, regs.ds):
 		*val = child->thread.ds;