[S390] remove reset of system call restart on psw changes

git commit 20b40a794baf3b4b "signal race with restarting system calls"
added code to the poke_user/poke_user_compat to reset the system call
restart information in the thread-info if the PSW address is changed.
The purpose of that change has been to workaround old gdbs that do
not know about the REGSET_SYSTEM_CALL. It turned out that this is not
a good idea, it makes the behaviour of the debuggee dependent on the
order of specific ptrace call, e.g. the REGSET_SYSTEM_CALL register
set needs to be written last. And the workaround does not really fix
old gdbs, inferior calls on interrupted restarting system calls do not
work either way.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index f05649f..573bc29 100644 (file)
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -296,13 +296,6 @@ static int __poke_user(struct task_struct *child, addr_t addr, addr_t data)
                     ((data & PSW_MASK_EA) && !(data & PSW_MASK_BA))))
                        /* Invalid psw mask. */
                        return -EINVAL;
-               if (addr == (addr_t) &dummy->regs.psw.addr)
-                       /*
-                        * The debugger changed the instruction address,
-                        * reset system call restart, see signal.c:do_signal
-                        */
-                       task_thread_info(child)->system_call = 0;
-
                *(addr_t *)((addr_t) &task_pt_regs(child)->psw + addr) = data;
 
        } else if (addr < (addr_t) (&dummy->regs.orig_gpr2)) {
@@ -614,11 +607,6 @@ static int __poke_user_compat(struct task_struct *child,
                        /* Transfer 31 bit amode bit to psw mask. */
                        regs->psw.mask = (regs->psw.mask & ~PSW_MASK_BA) |
                                (__u64)(tmp & PSW32_ADDR_AMODE);
-                       /*
-                        * The debugger changed the instruction address,
-                        * reset system call restart, see signal.c:do_signal
-                        */
-                       task_thread_info(child)->system_call = 0;
                } else {
                        /* gpr 0-15 */
                        *(__u32*)((addr_t) &regs->psw + addr*2 + 4) = tmp;