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	addi	$p1, $r0, #THREAD_CPU_CONTEXT
23	smw.bi 	$r6, [$p1], $r14, #0xb		! push r6~r14, fp, lp, sp
24	move	$r25, $r1
25#if defined(CONFIG_FPU)
26	call	_switch_fpu
27#endif
28	addi	$r1, $r25, #THREAD_CPU_CONTEXT
29	lmw.bi 	$r6, [$r1], $r14, #0xb		! pop r6~r14, fp, lp, sp
30	ret
31
32
33#define tbl $r8
34
35/*
36 * $r7 will be writen as syscall nr
37 */
38	.macro	get_scno
39	lwi	$r7, [$sp + R15_OFFSET]
40	swi	$r7, [$sp + SYSCALLNO_OFFSET]
41	.endm
42
43	.macro	updateipc
44	addi	$r17, $r13, #4				! $r13 is $IPC
45	swi	$r17, [$sp + IPC_OFFSET]
46	.endm
47
48ENTRY(eh_syscall)
49	updateipc
50
51	get_scno
52	gie_enable
53
54	lwi	$p0, [tsk+#TSK_TI_FLAGS]		! check for syscall tracing
55
56	andi	$p1, $p0, #_TIF_WORK_SYSCALL_ENTRY	! are we tracing syscalls?
57	bnez	$p1, __sys_trace
58
59	la	$lp, ret_fast_syscall		! return address
60jmp_systbl:
61	addi	$p1, $r7, #-__NR_syscalls	! syscall number of syscall instruction is guarded by addembler
62	bgez	$p1, _SCNO_EXCEED		! call sys_* routine
63	la	tbl, sys_call_table		! load syscall table pointer
64	slli	$p1, $r7, #2
65	add	$p1, tbl, $p1
66	lwi	$p1, [$p1]
67	jr	$p1				! no return
68
69_SCNO_EXCEED:
70	ori	$r0, $r7, #0
71        ori	$r1, $sp, #0
72	b	bad_syscall
73
74/*
75 * This is the really slow path.  We're going to be doing
76 * context switches, and waiting for our parent to respond.
77 */
78__sys_trace:
79	move	$r0, $sp
80	bal	syscall_trace_enter
81	move	$r7, $r0
82	la	$lp, __sys_trace_return		! return address
83
84	addi    $p1, $r7, #1
85	beqz    $p1, ret_slow_syscall		! fatal signal is pending
86
87	addi	$p1, $sp, #R0_OFFSET		! pointer to regs
88	lmw.bi	$r0, [$p1], $r5			! have to reload $r0 - $r5
89	b	jmp_systbl
90
91__sys_trace_return:
92	swi	$r0, [$sp+#R0_OFFSET]		! T: save returned $r0
93	move	$r0, $sp			! set pt_regs for syscall_trace_leave
94	bal	syscall_trace_leave
95	b	ret_slow_syscall
96
97ENTRY(sys_rt_sigreturn_wrapper)
98	addi	$r0, $sp, #0
99	b	sys_rt_sigreturn
100ENDPROC(sys_rt_sigreturn_wrapper)
101