Commit e3c7a8d7 authored by Sven Schnelle's avatar Sven Schnelle Committed by Vasily Gorbik
Browse files

s390: move restart of execve() syscall 



On s390, execve might have to be restarted for PGSTE binaries
like kvm. In the past this was done via the PIF_SYSCALL_RESTART
bit. However, with the recent changes, syscalls are now restarted
differently. Now that execve() is the only call that might get
restarted via PIF_SYSCALL_RESTART, move the loop to do_syscall().
This also has the advantage that the restart is no longer visible
to userspace.

Signed-off-by: default avatarSven Schnelle <svens@linux.ibm.com>
Reviewed-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent fbf50f47

arch/s390/include/asm/ptrace.h

+8 −0
Original line number Diff line number Diff line
@@ -162,6 +162,14 @@ static inline int test_pt_regs_flag(struct pt_regs *regs, int flag) 
	return !!(regs->flags & (1UL << flag));

}



static inline int test_and_clear_pt_regs_flag(struct pt_regs *regs, int flag)

{

	int ret = test_pt_regs_flag(regs, flag);



	clear_pt_regs_flag(regs, flag);

	return ret;

}



/*

 * These are defined as per linux/ptrace.h, which see.

 */

arch/s390/kernel/syscall.c

+12 −15
Original line number Diff line number Diff line
@@ -134,13 +134,15 @@ static void do_syscall(struct pt_regs *regs) 
	 * work, the ptrace code sets PIF_SYSCALL_RET_SET, which is checked here

	 * and if set, the syscall will be skipped.

	 */

	if (!test_pt_regs_flag(regs, PIF_SYSCALL_RET_SET)) {

	if (unlikely(test_and_clear_pt_regs_flag(regs, PIF_SYSCALL_RET_SET)))

		goto out;

	regs->gprs[2] = -ENOSYS;

		if (likely(nr < NR_syscalls))

	if (likely(nr >= NR_syscalls))

		goto out;

	do {

		regs->gprs[2] = current->thread.sys_call_table[nr](regs);

	} else {

		clear_pt_regs_flag(regs, PIF_SYSCALL_RET_SET);

	}

	} while (test_and_clear_pt_regs_flag(regs, PIF_SYSCALL_RESTART));

out:

	syscall_exit_to_user_mode_work(regs);

}
@@ -158,13 +160,8 @@ void noinstr __do_syscall(struct pt_regs *regs, int per_trap) 
	if (per_trap)

		set_thread_flag(TIF_PER_TRAP);



	for (;;) {

	regs->flags = 0;

	set_pt_regs_flag(regs, PIF_SYSCALL);

	do_syscall(regs);

		if (!test_pt_regs_flag(regs, PIF_SYSCALL_RESTART))

			break;

		local_irq_enable();

	}

	exit_to_user_mode();

}