xref: /freebsd/sys/riscv/riscv/copyinout.S (revision 0957b409)
1/*-
2 * Copyright (c) 2015-2018 Ruslan Bukin <br@bsdpad.com>
3 * Copyright (c) 2019 Mitchell Horne
4 * All rights reserved.
5 *
6 * Portions of this software were developed by SRI International and the
7 * University of Cambridge Computer Laboratory under DARPA/AFRL contract
8 * FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research programme.
9 *
10 * Portions of this software were developed by the University of Cambridge
11 * Computer Laboratory as part of the CTSRD Project, with support from the
12 * UK Higher Education Innovation Fund (HEIF).
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 *    notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 *    notice, this list of conditions and the following disclaimer in the
21 *    documentation and/or other materials provided with the distribution.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36#include <machine/asm.h>
37__FBSDID("$FreeBSD$");
38
39#include <machine/riscvreg.h>
40#include <sys/errno.h>
41
42#include "assym.inc"
43
44/*
45 * Fault handler for the copy{in,out} functions below.
46 */
47ENTRY(copyio_fault)
48	SET_FAULT_HANDLER(x0, a1) /* Clear the handler */
49	EXIT_USER_ACCESS(a1)
50copyio_fault_nopcb:
51	li	a0, EFAULT
52	ret
53END(copyio_fault)
54
55/*
56 * copycommon - common copy routine
57 *
58 * a0 - Source address
59 * a1 - Destination address
60 * a2 - Size of copy
61 */
62	.macro copycommon
63	la	a6, copyio_fault	/* Get the handler address */
64	SET_FAULT_HANDLER(a6, a7)	/* Set the handler */
65	ENTER_USER_ACCESS(a7)
66
67	li	t2, XLEN_BYTES
68	blt	a2, t2, 3f		/* Byte-copy if len < XLEN_BYTES */
69
70	/*
71	 * Compare lower bits of src and dest.
72	 * If they are aligned with each other, we can do word copy.
73	 */
74	andi	t0, a0, (XLEN_BYTES-1)	/* Low bits of src */
75	andi	t1, a1, (XLEN_BYTES-1)	/* Low bits of dest */
76	bne	t0, t1, 3f		/* Misaligned. Go to byte copy */
77	beqz	t0, 2f			/* Already word-aligned, skip ahead */
78
79	/* Byte copy until the first word-aligned address */
801:	lb	a4, 0(a0)		/* Load byte from src */
81	addi	a0, a0, 1
82	sb	a4, 0(a1)		/* Store byte in dest */
83	addi	a1, a1, 1
84	addi	a2, a2, -1		/* len-- */
85	andi	t0, a0, (XLEN_BYTES-1)
86	bnez	t0, 1b
87
88	/* Copy words */
892:	ld	a4, 0(a0)		/* Load word from src */
90	addi	a0, a0, XLEN_BYTES
91	sd	a4, 0(a1)		/* Store word in dest */
92	addi	a1, a1, XLEN_BYTES
93	addi	a2, a2, -XLEN_BYTES	/* len -= XLEN_BYTES */
94	bgeu	a2, t2, 2b		/* Again if len >= XLEN_BYTES */
95
96	/* Check if we're finished */
97	beqz	a2, 4f
98
99	/* Copy any remaining bytes */
1003:	lb	a4, 0(a0)		/* Load byte from src */
101	addi	a0, a0, 1
102	sb	a4, 0(a1)		/* Store byte in dest */
103	addi	a1, a1, 1
104	addi	a2, a2, -1		/* len-- */
105	bnez	a2, 3b
106
1074:	EXIT_USER_ACCESS(a7)
108	SET_FAULT_HANDLER(x0, a7)	/* Clear the handler */
109	.endm
110
111/*
112 * Copies from a kernel to user address
113 *
114 * int copyout(const void *kaddr, void *udaddr, size_t len)
115 */
116ENTRY(copyout)
117	beqz	a2, copyout_end	/* If len == 0 then skip loop */
118	add	a3, a1, a2
119	li	a4, VM_MAXUSER_ADDRESS
120	bgt	a3, a4, copyio_fault_nopcb
121
122	copycommon
123
124copyout_end:
125	li	a0, 0		/* return 0 */
126	ret
127END(copyout)
128
129/*
130 * Copies from a user to kernel address
131 *
132 * int copyin(const void *uaddr, void *kaddr, size_t len)
133 */
134ENTRY(copyin)
135	beqz	a2, copyin_end	/* If len == 0 then skip loop */
136	add	a3, a0, a2
137	li	a4, VM_MAXUSER_ADDRESS
138	bgt	a3, a4, copyio_fault_nopcb
139
140	copycommon
141
142copyin_end:
143	li	a0, 0		/* return 0 */
144	ret
145END(copyin)
146
147/*
148 * Copies a string from a user to kernel address
149 *
150 * int copyinstr(const void *udaddr, void *kaddr, size_t len, size_t *done)
151 */
152ENTRY(copyinstr)
153	mv	a5, x0		/* count = 0 */
154	beqz	a2, 3f		/* If len == 0 then skip loop */
155
156	la	a6, copyio_fault /* Get the handler address */
157	SET_FAULT_HANDLER(a6, a7) /* Set the handler */
158	ENTER_USER_ACCESS(a7)
159
160	li	a7, VM_MAXUSER_ADDRESS
1611:	bgt	a0, a7, copyio_fault
162	lb	a4, 0(a0)	/* Load from uaddr */
163	addi	a0, a0, 1
164	sb	a4, 0(a1)	/* Store in kaddr */
165	addi	a1, a1, 1
166	beqz	a4, 2f
167	addi	a2, a2, -1	/* len-- */
168	addi	a5, a5, 1	/* count++ */
169	bnez	a2, 1b
170
1712:	EXIT_USER_ACCESS(a7)
172	SET_FAULT_HANDLER(x0, a7) /* Clear the handler */
173
1743:	beqz	a3, 4f		/* Check if done != NULL */
175	addi	a5, a5, 1	/* count++ */
176	sd	a5, 0(a3)	/* done = count */
177
1784:	mv	a0, x0		/* return 0 */
179	beqz	a4, 5f
180	li	a0, ENAMETOOLONG
1815:
182	ret
183END(copyinstr)
184