[PATCH] x86_64: Fix 32bit system call restart

The test case at
http://cvs.sourceforge.net/viewcvs.py/posixtest/posixtestsuite/conforman
ce/interfaces/clock_nanosleep/1-5.c fails if it runs as a 32bit process on
x86_86 machines.

The root cause is the sub 32bit process fails to restart the syscall after it
is interrupted by a signal.

The syscall number of sys_restart_syscall in table sys_call_table is
__NR_restart_syscall (219) while it's __NR_ia32_restart_syscall
(0) in ia32_sys_call_table. When regs->rax==(unsigned
long)-ERESTART_RESTARTBLOCK, function do_signal doesn't distinguish if
the process is 64bit or 32bit, and always sets restart syscall number
as __NR_restart_syscall (219).
Signed-off-by: NZhang Yanmin <yanmin.zhang@intel.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

arch/x86_64/kernel/signal.c

@@ -452,7 +452,9 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
 			regs->rip -= 2;
 		}
 		if (regs->rax == (unsigned long)-ERESTART_RESTARTBLOCK) {
-			regs->rax = __NR_restart_syscall;
+			regs->rax = test_thread_flag(TIF_IA32) ?
+					__NR_ia32_restart_syscall :
+					__NR_restart_syscall;
 			regs->rip -= 2;
 		}
 	}