summaryrefslogtreecommitdiff
path: root/arch/arc/kernel/unaligned.c
blob: 91ebe382147f6d915a58f94027fa748ca8319f30 (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
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
/*
 * Copyright (C) 2011-2012 Synopsys (www.synopsys.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * vineetg : May 2011
 *  -Adapted (from .26 to .35)
 *  -original contribution by Tim.yao@amlogic.com
 *
 */

#include <linux/types.h>
#include <linux/perf_event.h>
#include <linux/ptrace.h>
#include <linux/uaccess.h>
#include <asm/disasm.h>

#ifdef CONFIG_CPU_BIG_ENDIAN
#define BE		1
#define FIRST_BYTE_16	"swap %1, %1\n swape %1, %1\n"
#define FIRST_BYTE_32	"swape %1, %1\n"
#else
#define BE		0
#define FIRST_BYTE_16
#define FIRST_BYTE_32
#endif

#define __get8_unaligned_check(val, addr, err)		\
	__asm__(					\
	"1:	ldb.ab	%1, [%2, 1]\n"			\
	"2:\n"						\
	"	.section .fixup,\"ax\"\n"		\
	"	.align	4\n"				\
	"3:	mov	%0, 1\n"			\
	"	j	2b\n"				\
	"	.previous\n"				\
	"	.section __ex_table,\"a\"\n"		\
	"	.align	4\n"				\
	"	.long	1b, 3b\n"			\
	"	.previous\n"				\
	: "=r" (err), "=&r" (val), "=r" (addr)		\
	: "0" (err), "2" (addr))

#define get16_unaligned_check(val, addr)		\
	do {						\
		unsigned int err = 0, v, a = addr;	\
		__get8_unaligned_check(v, a, err);	\
		val =  v << ((BE) ? 8 : 0);		\
		__get8_unaligned_check(v, a, err);	\
		val |= v << ((BE) ? 0 : 8);		\
		if (err)				\
			goto fault;			\
	} while (0)

#define get32_unaligned_check(val, addr)		\
	do {						\
		unsigned int err = 0, v, a = addr;	\
		__get8_unaligned_check(v, a, err);	\
		val =  v << ((BE) ? 24 : 0);		\
		__get8_unaligned_check(v, a, err);	\
		val |= v << ((BE) ? 16 : 8);		\
		__get8_unaligned_check(v, a, err);	\
		val |= v << ((BE) ? 8 : 16);		\
		__get8_unaligned_check(v, a, err);	\
		val |= v << ((BE) ? 0 : 24);		\
		if (err)				\
			goto fault;			\
	} while (0)

#define put16_unaligned_check(val, addr)		\
	do {						\
		unsigned int err = 0, v = val, a = addr;\
							\
		__asm__(				\
		FIRST_BYTE_16				\
		"1:	stb.ab	%1, [%2, 1]\n"		\
		"	lsr %1, %1, 8\n"		\
		"2:	stb	%1, [%2]\n"		\
		"3:\n"					\
		"	.section .fixup,\"ax\"\n"	\
		"	.align	4\n"			\
		"4:	mov	%0, 1\n"		\
		"	j	3b\n"			\
		"	.previous\n"			\
		"	.section __ex_table,\"a\"\n"	\
		"	.align	4\n"			\
		"	.long	1b, 4b\n"		\
		"	.long	2b, 4b\n"		\
		"	.previous\n"			\
		: "=r" (err), "=&r" (v), "=&r" (a)	\
		: "0" (err), "1" (v), "2" (a));		\
							\
		if (err)				\
			goto fault;			\
	} while (0)

#define put32_unaligned_check(val, addr)		\
	do {						\
		unsigned int err = 0, v = val, a = addr;\
							\
		__asm__(				\
		FIRST_BYTE_32				\
		"1:	stb.ab	%1, [%2, 1]\n"		\
		"	lsr %1, %1, 8\n"		\
		"2:	stb.ab	%1, [%2, 1]\n"		\
		"	lsr %1, %1, 8\n"		\
		"3:	stb.ab	%1, [%2, 1]\n"		\
		"	lsr %1, %1, 8\n"		\
		"4:	stb	%1, [%2]\n"		\
		"5:\n"					\
		"	.section .fixup,\"ax\"\n"	\
		"	.align	4\n"			\
		"6:	mov	%0, 1\n"		\
		"	j	5b\n"			\
		"	.previous\n"			\
		"	.section __ex_table,\"a\"\n"	\
		"	.align	4\n"			\
		"	.long	1b, 6b\n"		\
		"	.long	2b, 6b\n"		\
		"	.long	3b, 6b\n"		\
		"	.long	4b, 6b\n"		\
		"	.previous\n"			\
		: "=r" (err), "=&r" (v), "=&r" (a)	\
		: "0" (err), "1" (v), "2" (a));		\
							\
		if (err)				\
			goto fault;			\
	} while (0)

/* sysctl hooks */
int unaligned_enabled __read_mostly = 1;	/* Enabled by default */
int no_unaligned_warning __read_mostly = 1;	/* Only 1 warning by default */

static void fixup_load(struct disasm_state *state, struct pt_regs *regs,
			struct callee_regs *cregs)
{
	int val;

	/* register write back */
	if ((state->aa == 1) || (state->aa == 2)) {
		set_reg(state->wb_reg, state->src1 + state->src2, regs, cregs);

		if (state->aa == 2)
			state->src2 = 0;
	}

	if (state->zz == 0) {
		get32_unaligned_check(val, state->src1 + state->src2);
	} else {
		get16_unaligned_check(val, state->src1 + state->src2);

		if (state->x)
			val = (val << 16) >> 16;
	}

	if (state->pref == 0)
		set_reg(state->dest, val, regs, cregs);

	return;

fault:	state->fault = 1;
}

static void fixup_store(struct disasm_state *state, struct pt_regs *regs,
			struct callee_regs *cregs)
{
	/* register write back */
	if ((state->aa == 1) || (state->aa == 2)) {
		set_reg(state->wb_reg, state->src2 + state->src3, regs, cregs);

		if (state->aa == 3)
			state->src3 = 0;
	} else if (state->aa == 3) {
		if (state->zz == 2) {
			set_reg(state->wb_reg, state->src2 + (state->src3 << 1),
				regs, cregs);
		} else if (!state->zz) {
			set_reg(state->wb_reg, state->src2 + (state->src3 << 2),
				regs, cregs);
		} else {
			goto fault;
		}
	}

	/* write fix-up */
	if (!state->zz)
		put32_unaligned_check(state->src1, state->src2 + state->src3);
	else
		put16_unaligned_check(state->src1, state->src2 + state->src3);

	return;

fault:	state->fault = 1;
}

/*
 * Handle an unaligned access
 * Returns 0 if successfully handled, 1 if some error happened
 */
int misaligned_fixup(unsigned long address, struct pt_regs *regs,
		     struct callee_regs *cregs)
{
	struct disasm_state state;
	char buf[TASK_COMM_LEN];

	/* handle user mode only and only if enabled by sysadmin */
	if (!user_mode(regs) || !unaligned_enabled)
		return 1;

	if (no_unaligned_warning) {
		pr_warn_once("%s(%d) made unaligned access which was emulated"
			     " by kernel assist\n. This can degrade application"
			     " performance significantly\n. To enable further"
			     " logging of such instances, please \n"
			     " echo 0 > /proc/sys/kernel/ignore-unaligned-usertrap\n",
			     get_task_comm(buf, current), task_pid_nr(current));
	} else {
		/* Add rate limiting if it gets down to it */
		pr_warn("%s(%d): unaligned access to/from 0x%lx by PC: 0x%lx\n",
			get_task_comm(buf, current), task_pid_nr(current),
			address, regs->ret);

	}

	disasm_instr(regs->ret, &state, 1, regs, cregs);

	if (state.fault)
		goto fault;

	/* ldb/stb should not have unaligned exception */
	if ((state.zz == 1) || (state.di))
		goto fault;

	if (!state.write)
		fixup_load(&state, regs, cregs);
	else
		fixup_store(&state, regs, cregs);

	if (state.fault)
		goto fault;

	/* clear any remanants of delay slot */
	if (delay_mode(regs)) {
		regs->ret = regs->bta ~1U;
		regs->status32 &= ~STATUS_DE_MASK;
	} else {
		regs->ret += state.instr_len;

		/* handle zero-overhead-loop */
		if ((regs->ret == regs->lp_end) && (regs->lp_count)) {
			regs->ret = regs->lp_start;
			regs->lp_count--;
		}
	}

	perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, address);
	return 0;

fault:
	pr_err("Alignment trap: fault in fix-up %08lx at [<%08lx>]\n",
		state.words[0], address);

	return 1;
}