Commit a0f2a8d0 authored by Heiko Carstens's avatar Heiko Carstens Committed by Vasily Gorbik
Browse files

s390/syscall: Merge __do_syscall() and do_syscall() 



The compiler inlines do_syscall() into __do_syscall(). Therefore do this in
C code as well, since this makes the code easier to understand.

Also adjust and add various unlikely() and likely() annotations.

Furthermore this allows to replace the separate exit_to_user_mode() and
syscall_exit_to_user_mode_work() calls with a combined
syscall_exit_to_user_mode() call which results in slightly better code.

Acked-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent b4652543

arch/s390/kernel/syscall.c

+17 −30
Original line number Diff line number Diff line
@@ -82,25 +82,35 @@ SYSCALL_DEFINE0(ni_syscall) 
	return -ENOSYS;

}



static void do_syscall(struct pt_regs *regs)

void noinstr __do_syscall(struct pt_regs *regs, int per_trap)

{

	unsigned long nr;



	add_random_kstack_offset();

	enter_from_user_mode(regs);

	regs->psw = get_lowcore()->svc_old_psw;

	regs->int_code = get_lowcore()->svc_int_code;

	update_timer_sys();

	if (cpu_has_bear())

		current->thread.last_break = regs->last_break;

	local_irq_enable();

	regs->orig_gpr2 = regs->gprs[2];

	if (unlikely(per_trap))

		set_thread_flag(TIF_PER_TRAP);

	regs->flags = 0;

	set_pt_regs_flag(regs, PIF_SYSCALL);

	nr = regs->int_code & 0xffff;

	if (!nr) {

	if (likely(!nr)) {

		nr = regs->gprs[1] & 0xffff;

		regs->int_code &= ~0xffffUL;

		regs->int_code |= nr;

	}



	regs->gprs[2] = nr;



	if (nr == __NR_restart_syscall && !(current->restart_block.arch_data & 1)) {

		regs->psw.addr = current->restart_block.arch_data;

		current->restart_block.arch_data = 1;

	}

	nr = syscall_enter_from_user_mode_work(regs, nr);



	/*

	 * In the s390 ptrace ABI, both the syscall number and the return value

	 * use gpr2. However, userspace puts the syscall number either in the
@@ -108,37 +118,14 @@ 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 (unlikely(test_and_clear_pt_regs_flag(regs, PIF_SYSCALL_RET_SET)))

		goto out;

	regs->gprs[2] = -ENOSYS;

	if (likely(nr >= NR_syscalls))

	if (unlikely(nr >= NR_syscalls))

		goto out;

	do {

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

	} while (test_and_clear_pt_regs_flag(regs, PIF_EXECVE_PGSTE_RESTART));

out:

	syscall_exit_to_user_mode_work(regs);

}



void noinstr __do_syscall(struct pt_regs *regs, int per_trap)

{

	add_random_kstack_offset();

	enter_from_user_mode(regs);

	regs->psw = get_lowcore()->svc_old_psw;

	regs->int_code = get_lowcore()->svc_int_code;

	update_timer_sys();

	if (cpu_has_bear())

		current->thread.last_break = regs->last_break;



	local_irq_enable();

	regs->orig_gpr2 = regs->gprs[2];



	if (per_trap)

		set_thread_flag(TIF_PER_TRAP);



	regs->flags = 0;

	set_pt_regs_flag(regs, PIF_SYSCALL);

	do_syscall(regs);

	exit_to_user_mode();

	syscall_exit_to_user_mode(regs);

}