1// SPDX-License-Identifier: GPL-2.0
2// Copyright (C) 2005-2017 Andes Technology Corporation
3
4#include <linux/linkage.h>
5#include <asm/unistd.h>
6#include <asm/assembler.h>
7#include <asm/nds32.h>
8#include <asm/asm-offsets.h>
9#include <asm/thread_info.h>
10#include <asm/current.h>
11
12/*
13 * $r0 = previous task_struct,
14 * $r1 = next task_struct,
15 * previous and next are guaranteed not to be the same.
16 */
17
18ENTRY(__switch_to)
19
20	la	$p0, __entry_task
21	sw	$r1, [$p0]
22	move	$p1, $r0
23	addi	$p1, $p1, #THREAD_CPU_CONTEXT
24	smw.bi 	$r6, [$p1], $r14, #0xb		! push r6~r14, fp, lp, sp
25	move	$r25, $r1
26	addi	$r1, $r1, #THREAD_CPU_CONTEXT
27	lmw.bi 	$r6, [$r1], $r14, #0xb		! pop r6~r14, fp, lp, sp
28	ret
29
30
31#define tbl $r8
32
33/*
34 * $r7 will be writen as syscall nr
35 */
36	.macro	get_scno
37	lwi	$r7, [$sp + R15_OFFSET]
38	swi	$r7, [$sp + SYSCALLNO_OFFSET]
39	.endm
40
41	.macro	updateipc
42	addi	$r17, $r13, #4				! $r13 is $IPC
43	swi	$r17, [$sp + IPC_OFFSET]
44	.endm
45
46ENTRY(eh_syscall)
47	updateipc
48
49	get_scno
50	gie_enable
51
52	lwi	$p0, [tsk+#TSK_TI_FLAGS]		! check for syscall tracing
53
54	andi	$p1, $p0, #_TIF_WORK_SYSCALL_ENTRY	! are we tracing syscalls?
55	bnez	$p1, __sys_trace
56
57	la	$lp, ret_fast_syscall		! return address
58jmp_systbl:
59	addi	$p1, $r7, #-__NR_syscalls	! syscall number of syscall instruction is guarded by addembler
60	bgez	$p1, _SCNO_EXCEED		! call sys_* routine
61	la	tbl, sys_call_table		! load syscall table pointer
62	slli	$p1, $r7, #2
63	add	$p1, tbl, $p1
64	lwi	$p1, [$p1]
65	jr	$p1				! no return
66
67_SCNO_EXCEED:
68	ori	$r0, $r7, #0
69        ori	$r1, $sp, #0
70	b	bad_syscall
71
72/*
73 * This is the really slow path.  We're going to be doing
74 * context switches, and waiting for our parent to respond.
75 */
76__sys_trace:
77	move	$r0, $sp
78	bal	syscall_trace_enter
79	move	$r7, $r0
80	la	$lp, __sys_trace_return		! return address
81
82	addi    $p1, $r7, #1
83	beqz    $p1, ret_slow_syscall		! fatal signal is pending
84
85	addi	$p1, $sp, #R0_OFFSET		! pointer to regs
86	lmw.bi	$r0, [$p1], $r5			! have to reload $r0 - $r5
87	b	jmp_systbl
88
89__sys_trace_return:
90	swi	$r0, [$sp+#R0_OFFSET]		! T: save returned $r0
91	move	$r0, $sp			! set pt_regs for syscall_trace_leave
92	bal	syscall_trace_leave
93	b	ret_slow_syscall
94
95ENTRY(sys_rt_sigreturn_wrapper)
96	addi	$r0, $sp, #0
97	b	sys_rt_sigreturn
98ENDPROC(sys_rt_sigreturn_wrapper)
99