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#include <asm/fpu.h>
 12
 13
 14
 15#ifdef CONFIG_HWZOL
 16	.macro pop_zol
 17	mtusr	$r14, $LB
 18	mtusr	$r15, $LE
 19	mtusr	$r16, $LC
 20	.endm
 21#endif
 22
 23	.macro	restore_user_regs_first
 24	setgie.d
 25	isb
 26#if defined(CONFIG_FPU)
 27	addi    $sp, $sp, OSP_OFFSET
 28	lmw.adm $r12, [$sp], $r25, #0x0
 29	sethi   $p0, hi20(has_fpu)
 30	lbsi 	$p0, [$p0+lo12(has_fpu)]
 31	beqz	$p0, 2f
 32	mtsr    $r25, $FUCOP_CTL
 332:
 34#else
 35	addi	$sp, $sp, FUCOP_CTL_OFFSET
 36	lmw.adm $r12, [$sp], $r24, #0x0
 37#endif
 38	mtsr	$r12, $SP_USR
 39	mtsr	$r13, $IPC
 40#ifdef CONFIG_HWZOL
 41	pop_zol
 42#endif
 43	mtsr	$r19, $PSW
 44	mtsr	$r20, $IPSW
 45	mtsr    $r21, $P_IPSW
 46	mtsr	$r22, $P_IPC
 47	mtsr	$r23, $P_P0
 48	mtsr	$r24, $P_P1
 49	lmw.adm $sp, [$sp], $sp, #0xe
 50	.endm
 51
 52	.macro	restore_user_regs_last
 53	pop	$p0
 54	cmovn	$sp, $p0, $p0
 55
 56	iret
 57	nop
 58
 59	.endm
 60
 61	.macro	restore_user_regs
 62	restore_user_regs_first
 63	lmw.adm $r0, [$sp], $r25, #0x0
 64	addi	$sp, $sp, OSP_OFFSET
 65	restore_user_regs_last
 66	.endm
 67
 68	.macro	fast_restore_user_regs
 69	restore_user_regs_first
 70	lmw.adm $r1, [$sp], $r25, #0x0
 71	addi	$sp, $sp, OSP_OFFSET-4
 72	restore_user_regs_last
 73	.endm
 74
 75#ifdef CONFIG_PREEMPTION
 76	.macro	preempt_stop
 77	.endm
 78#else
 79	.macro	preempt_stop
 80	setgie.d
 81	isb
 82	.endm
 83#define	resume_kernel	no_work_pending
 84#endif
 85
 86ENTRY(ret_from_exception)
 87	preempt_stop
 88ENTRY(ret_from_intr)
 89
 90/*
 91 * judge Kernel or user mode
 92 *
 93 */
 94	lwi	$p0, [$sp+(#IPSW_OFFSET)]	! Check if in nested interrupt
 95	andi	$p0, $p0, #PSW_mskINTL
 96	bnez	$p0, resume_kernel		! done with iret
 97	j	resume_userspace
 98
 99
100/*
101 * This is the fast syscall return path.  We do as little as
102 * possible here, and this includes saving $r0 back into the SVC
103 * stack.
104 * fixed: tsk - $r25, syscall # - $r7, syscall table pointer - $r8
105 */
106ENTRY(ret_fast_syscall)
107	gie_disable
108	lwi	$r1, [tsk+#TSK_TI_FLAGS]
109	andi	$p1, $r1, #_TIF_WORK_MASK
110	bnez	$p1, fast_work_pending
111	fast_restore_user_regs			! iret
112
113/*
114 * Ok, we need to do extra processing,
115 * enter the slow path returning from syscall, while pending work.
116 */
117fast_work_pending:
118	swi	$r0, [$sp+(#R0_OFFSET)]		! what is different from ret_from_exception
119work_pending:
120	andi	$p1, $r1, #_TIF_NEED_RESCHED
121	bnez	$p1, work_resched
122
123	andi	$p1, $r1, #_TIF_SIGPENDING|#_TIF_NOTIFY_RESUME|#_TIF_NOTIFY_SIGNAL
124	beqz	$p1, no_work_pending
125
126	move	$r0, $sp			! 'regs'
127	gie_enable
128	bal	do_notify_resume
129	b       ret_slow_syscall
130work_resched:
131	bal	schedule			! path, return to user mode
132
133/*
134 * "slow" syscall return path.
135 */
136ENTRY(resume_userspace)
137ENTRY(ret_slow_syscall)
138	gie_disable
139	lwi	$p0, [$sp+(#IPSW_OFFSET)]	! Check if in nested interrupt
140	andi	$p0, $p0, #PSW_mskINTL
141	bnez	$p0, no_work_pending		! done with iret
142	lwi	$r1, [tsk+#TSK_TI_FLAGS]
143	andi	$p1, $r1, #_TIF_WORK_MASK
144	bnez	$p1, work_pending		! handle work_resched, sig_pend
145
146no_work_pending:
147#ifdef CONFIG_TRACE_IRQFLAGS
148	lwi	$p0, [$sp+(#IPSW_OFFSET)]
149	andi	$p0, $p0, #0x1
150	la	$r10, __trace_hardirqs_off
151	la	$r9, __trace_hardirqs_on
152	cmovz	$r9, $p0, $r10
153	jral	$r9
154#endif
155	restore_user_regs			! return from iret
156
157
158/*
159 * preemptive kernel
160 */
161#ifdef CONFIG_PREEMPTION
162resume_kernel:
163	gie_disable
164	lwi	$t0, [tsk+#TSK_TI_PREEMPT]
165	bnez	$t0, no_work_pending
166
167	lwi	$t0, [tsk+#TSK_TI_FLAGS]
168	andi	$p1, $t0, #_TIF_NEED_RESCHED
169	beqz	$p1, no_work_pending
170
171	lwi	$t0, [$sp+(#IPSW_OFFSET)]	! Interrupts off?
172	andi	$t0, $t0, #1
173	beqz	$t0, no_work_pending
174
175	jal	preempt_schedule_irq
176	b	no_work_pending
177#endif
178
179/*
180 * This is how we return from a fork.
181 */
182ENTRY(ret_from_fork)
183	bal	schedule_tail
184	beqz	$r6, 1f				! r6 stores fn for kernel thread
185	move	$r0, $r7			! prepare kernel thread arg
186	jral	$r6
1871:
188	lwi	$r1, [tsk+#TSK_TI_FLAGS]		! check for syscall tracing
189	andi	$p1, $r1, #_TIF_WORK_SYSCALL_LEAVE	! are we tracing syscalls?
190	beqz	$p1, ret_slow_syscall
191	move    $r0, $sp
192	bal	syscall_trace_leave
193	b	ret_slow_syscall