Fix compat emulation of PTRACE_GET/SET_THREAD_AREA

Since the 64bit kernel has different indexes for this TLS segments
the address needs to be adjusted in the ptrace 32bit emulation.

Based on report from Amnon Shiloh
Signed-off-by: Andi Kleen <ak@suse.de>

---
 arch/x86_64/ia32/ptrace32.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Index: linux/arch/x86_64/ia32/ptrace32.c
===================================================================
--- linux.orig/arch/x86_64/ia32/ptrace32.c
+++ linux/arch/x86_64/ia32/ptrace32.c
@@ -228,6 +228,8 @@ static long ptrace32_siginfo(unsigned re
 	return ret;
 }
 
+#define COMPAT_GDT_ENTRY_TLS_MIN 6
+
 asmlinkage long sys32_ptrace(long request, u32 pid, u32 addr, u32 data)
 {
 	struct task_struct *child;
@@ -246,8 +248,6 @@ asmlinkage long sys32_ptrace(long reques
 	case PTRACE_SYSCALL:
 	case PTRACE_OLDSETOPTIONS:
 	case PTRACE_SETOPTIONS:
-	case PTRACE_SET_THREAD_AREA:
-	case PTRACE_GET_THREAD_AREA:
 		return sys_ptrace(request, pid, addr, data); 
 
 	default:
@@ -271,6 +271,12 @@ asmlinkage long sys32_ptrace(long reques
 	case PTRACE_SETSIGINFO:
 	case PTRACE_GETSIGINFO:
 		return ptrace32_siginfo(request, pid, addr, data);
+
+	case PTRACE_SET_THREAD_AREA:
+	case PTRACE_GET_THREAD_AREA:
+		return sys_ptrace(request, pid,
+			addr + GDT_ENTRY_TLS_MIN - COMPAT_GDT_ENTRY_TLS_MIN,
+			data);
 	}
 
 	child = ptrace_get_task_struct(pid);