[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: Zhang Yanmin <yanmin.zhang@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/x86_64/kernel/signal.c b/arch/x86_64/kernel/signal.c
index d439ced150c6..3fdcdba0fec5 100644
--- a/arch/x86_64/kernel/signal.c
+++ b/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;
                 }
         }