summaryrefslogtreecommitdiffstats
path: root/arch/frv/mm/unaligned.c
blob: 09b361443fc2c990faae75372bf58a350cfccae2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
/* unaligned.c: unalignment fixup handler for CPUs on which it is supported (FR451 only)
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/config.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/user.h>
#include <linux/string.h>
#include <linux/linkage.h>
#include <linux/init.h>

#include <asm/setup.h>
#include <asm/system.h>
#include <asm/uaccess.h>

#if 0
#define kdebug(fmt, ...) printk("FDPIC "fmt"\n" ,##__VA_ARGS__ )
#else
#define kdebug(fmt, ...) do {} while(0)
#endif

#define _MA_SIGNED	0x01
#define _MA_HALF	0x02
#define _MA_WORD	0x04
#define _MA_DWORD	0x08
#define _MA_SZ_MASK	0x0e
#define _MA_LOAD	0x10
#define _MA_STORE	0x20
#define _MA_UPDATE	0x40
#define _MA_IMM		0x80

#define _MA_LDxU	_MA_LOAD | _MA_UPDATE
#define _MA_LDxI	_MA_LOAD | _MA_IMM
#define _MA_STxU	_MA_STORE | _MA_UPDATE
#define _MA_STxI	_MA_STORE | _MA_IMM

static const uint8_t tbl_LDGRk_reg[0x40] = {
	[0x02] = _MA_LOAD | _MA_HALF | _MA_SIGNED,	/* LDSH  @(GRi,GRj),GRk */
	[0x03] = _MA_LOAD | _MA_HALF,			/* LDUH  @(GRi,GRj),GRk */
	[0x04] = _MA_LOAD | _MA_WORD,			/* LD	 @(GRi,GRj),GRk */
	[0x05] = _MA_LOAD | _MA_DWORD,			/* LDD	 @(GRi,GRj),GRk */
	[0x12] = _MA_LDxU | _MA_HALF | _MA_SIGNED,	/* LDSHU @(GRi,GRj),GRk */
	[0x13] = _MA_LDxU | _MA_HALF,			/* LDUHU @(GRi,GRj),GRk */
	[0x14] = _MA_LDxU | _MA_WORD,			/* LDU	 @(GRi,GRj),GRk */
	[0x15] = _MA_LDxU | _MA_DWORD,			/* LDDU	 @(GRi,GRj),GRk */
};

static const uint8_t tbl_STGRk_reg[0x40] = {
	[0x01] = _MA_STORE | _MA_HALF,			/* STH   @(GRi,GRj),GRk */
	[0x02] = _MA_STORE | _MA_WORD,			/* ST	 @(GRi,GRj),GRk */
	[0x03] = _MA_STORE | _MA_DWORD,			/* STD	 @(GRi,GRj),GRk */
	[0x11] = _MA_STxU  | _MA_HALF,			/* STHU  @(GRi,GRj),GRk */
	[0x12] = _MA_STxU  | _MA_WORD,			/* STU	 @(GRi,GRj),GRk */
	[0x13] = _MA_STxU  | _MA_DWORD,			/* STDU	 @(GRi,GRj),GRk */
};

static const uint8_t tbl_LDSTGRk_imm[0x80] = {
	[0x31] = _MA_LDxI | _MA_HALF | _MA_SIGNED,	/* LDSHI @(GRi,d12),GRk */
	[0x32] = _MA_LDxI | _MA_WORD,			/* LDI   @(GRi,d12),GRk */
	[0x33] = _MA_LDxI | _MA_DWORD,			/* LDDI  @(GRi,d12),GRk */
	[0x36] = _MA_LDxI | _MA_HALF,			/* LDUHI @(GRi,d12),GRk */
	[0x51] = _MA_STxI | _MA_HALF,			/* STHI  @(GRi,d12),GRk */
	[0x52] = _MA_STxI | _MA_WORD,			/* STI   @(GRi,d12),GRk */
	[0x53] = _MA_STxI | _MA_DWORD,			/* STDI  @(GRi,d12),GRk */
};


/*****************************************************************************/
/*
 * see if we can handle the exception by fixing up a misaligned memory access
 */
int handle_misalignment(unsigned long esr0, unsigned long ear0, unsigned long epcr0)
{
	unsigned long insn, addr, *greg;
	int GRi, GRj, GRk, D12, op;

	union {
		uint64_t _64;
		uint32_t _32[2];
		uint16_t _16;
		uint8_t _8[8];
	} x;

	if (!(esr0 & ESR0_EAV) || !(epcr0 & EPCR0_V) || !(ear0 & 7))
		return -EAGAIN;

	epcr0 &= EPCR0_PC;

	if (__frame->pc != epcr0) {
		kdebug("MISALIGN: Execution not halted on excepting instruction\n");
		BUG();
	}

	if (__get_user(insn, (unsigned long *) epcr0) < 0)
		return -EFAULT;

	/* determine the instruction type first */
	switch ((insn >> 18) & 0x7f) {
	case 0x2:
		/* LDx @(GRi,GRj),GRk */
		op = tbl_LDGRk_reg[(insn >> 6) & 0x3f];
		break;

	case 0x3:
		/* STx GRk,@(GRi,GRj) */
		op = tbl_STGRk_reg[(insn >> 6) & 0x3f];
		break;

	default:
		op = tbl_LDSTGRk_imm[(insn >> 18) & 0x7f];
		break;
	}

	if (!op)
		return -EAGAIN;

	kdebug("MISALIGN: pc=%08lx insn=%08lx ad=%08lx op=%02x\n", epcr0, insn, ear0, op);

	memset(&x, 0xba, 8);

	/* validate the instruction parameters */
	greg = (unsigned long *) &__frame->tbr;

	GRi = (insn >> 12) & 0x3f;
	GRk = (insn >> 25) & 0x3f;

	if (GRi > 31 || GRk > 31)
		return -ENOENT;

	if (op & _MA_DWORD && GRk & 1)
		return -EINVAL;

	if (op & _MA_IMM) {
		D12 = insn & 0xfff;
		asm ("slli %0,#20,%0 ! srai %0,#20,%0" : "=r"(D12) : "0"(D12)); /* sign extend */
		addr = (GRi ? greg[GRi] : 0) + D12;
	}
	else {
		GRj = (insn >>  0) & 0x3f;
		if (GRj > 31)
			return -ENOENT;
		addr = (GRi ? greg[GRi] : 0) + (GRj ? greg[GRj] : 0);
	}

	if (addr != ear0) {
		kdebug("MISALIGN: Calculated addr (%08lx) does not match EAR0 (%08lx)\n",
		       addr, ear0);
		return -EFAULT;
	}

	/* check the address is okay */
	if (user_mode(__frame) && ___range_ok(ear0, 8) < 0)
		return -EFAULT;

	/* perform the memory op */
	if (op & _MA_STORE) {
		/* perform a store */
		x._32[0] = 0;
		if (GRk != 0) {
			if (op & _MA_HALF) {
				x._16 = greg[GRk];
			}
			else {
				x._32[0] = greg[GRk];
			}
		}
		if (op & _MA_DWORD)
			x._32[1] = greg[GRk + 1];

		kdebug("MISALIGN: Store GR%d { %08x:%08x } -> %08lx (%dB)\n",
		       GRk, x._32[1], x._32[0], addr, op & _MA_SZ_MASK);

		if (__memcpy_user((void *) addr, &x, op & _MA_SZ_MASK) != 0)
			return -EFAULT;
	}
	else {
		/* perform a load */
		if (__memcpy_user(&x, (void *) addr, op & _MA_SZ_MASK) != 0)
			return -EFAULT;

		if (op & _MA_HALF) {
			if (op & _MA_SIGNED)
				asm ("slli %0,#16,%0 ! srai %0,#16,%0"
				     : "=r"(x._32[0]) : "0"(x._16));
			else
				asm ("sethi #0,%0"
				     : "=r"(x._32[0]) : "0"(x._16));
		}

		kdebug("MISALIGN: Load %08lx (%dB) -> GR%d, { %08x:%08x }\n",
		       addr, op & _MA_SZ_MASK, GRk, x._32[1], x._32[0]);

		if (GRk != 0)
			greg[GRk] = x._32[0];
		if (op & _MA_DWORD)
			greg[GRk + 1] = x._32[1];
	}

	/* update the base pointer if required */
	if (op & _MA_UPDATE)
		greg[GRi] = addr;

	/* well... we've done that insn */
	__frame->pc = __frame->pc + 4;

	return 0;
} /* end handle_misalignment() */