aboutsummaryrefslogtreecommitdiff
path: root/arch/sparc/kernel/muldiv.c
blob: ba960c02bb55eedeb3b7c15cdf6e37e59cd8dd58 (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
/*
 * muldiv.c: Hardware multiply/division illegal instruction trap
 *		for sun4c/sun4 (which do not have those instructions)
 *
 * Copyright (C) 1996 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
 * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
 *
 * 2004-12-25	Krzysztof Helt (krzysztof.h1@wp.pl) 
 *		- fixed registers constrains in inline assembly declarations
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <asm/ptrace.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/uaccess.h>

#include "kernel.h"

/* #define DEBUG_MULDIV */

static inline int has_imm13(int insn)
{
	return (insn & 0x2000);
}

static inline int is_foocc(int insn)
{
	return (insn & 0x800000);
}

static inline int sign_extend_imm13(int imm)
{
	return imm << 19 >> 19;
}

static inline void advance(struct pt_regs *regs)
{
	regs->pc   = regs->npc;
	regs->npc += 4;
}

static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
				       unsigned int rd)
{
	if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
		/* Wheee... */
		__asm__ __volatile__("save %sp, -0x40, %sp\n\t"
				     "save %sp, -0x40, %sp\n\t"
				     "save %sp, -0x40, %sp\n\t"
				     "save %sp, -0x40, %sp\n\t"
				     "save %sp, -0x40, %sp\n\t"
				     "save %sp, -0x40, %sp\n\t"
				     "save %sp, -0x40, %sp\n\t"
				     "restore; restore; restore; restore;\n\t"
				     "restore; restore; restore;\n\t");
	}
}

#define fetch_reg(reg, regs) ({						\
	struct reg_window __user *win;					\
	register unsigned long ret;					\
									\
	if (!(reg)) ret = 0;						\
	else if ((reg) < 16) {						\
		ret = regs->u_regs[(reg)];				\
	} else {							\
		/* Ho hum, the slightly complicated case. */		\
		win = (struct reg_window __user *)regs->u_regs[UREG_FP];\
		if (get_user (ret, &win->locals[(reg) - 16])) return -1;\
	}								\
	ret;								\
})

static inline int
store_reg(unsigned int result, unsigned int reg, struct pt_regs *regs)
{
	struct reg_window __user *win;

	if (!reg)
		return 0;
	if (reg < 16) {
		regs->u_regs[reg] = result;
		return 0;
	} else {
		/* need to use put_user() in this case: */
		win = (struct reg_window __user *) regs->u_regs[UREG_FP];
		return (put_user(result, &win->locals[reg - 16]));
	}
}

/* Should return 0 if mul/div emulation succeeded and SIGILL should
 * not be issued.
 */
int do_user_muldiv(struct pt_regs *regs, unsigned long pc)
{
	unsigned int insn;
	int inst;
	unsigned int rs1, rs2, rdv;

	if (!pc)
		return -1; /* This happens to often, I think */
	if (get_user (insn, (unsigned int __user *)pc))
		return -1;
	if ((insn & 0xc1400000) != 0x80400000)
		return -1;
	inst = ((insn >> 19) & 0xf);
	if ((inst & 0xe) != 10 && (inst & 0xe) != 14)
		return -1;

	/* Now we know we have to do something with umul, smul, udiv or sdiv */
	rs1 = (insn >> 14) & 0x1f;
	rs2 = insn & 0x1f;
	rdv = (insn >> 25) & 0x1f;
	if (has_imm13(insn)) {
		maybe_flush_windows(rs1, 0, rdv);
		rs2 = sign_extend_imm13(insn);
	} else {
		maybe_flush_windows(rs1, rs2, rdv);
		rs2 = fetch_reg(rs2, regs);
	}
	rs1 = fetch_reg(rs1, regs);
	switch (inst) {
	case 10: /* umul */
#ifdef DEBUG_MULDIV	
		printk ("unsigned muldiv: 0x%x * 0x%x = ", rs1, rs2);
#endif		
		__asm__ __volatile__ ("\n\t"
			"mov	%0, %%o0\n\t"
			"call	.umul\n\t"
			" mov	%1, %%o1\n\t"
			"mov	%%o0, %0\n\t"
			"mov	%%o1, %1\n\t"
			: "=r" (rs1), "=r" (rs2)
		        : "0" (rs1), "1" (rs2)
			: "o0", "o1", "o2", "o3", "o4", "o5", "o7", "cc");
#ifdef DEBUG_MULDIV
		printk ("0x%x%08x\n", rs2, rs1);
#endif
		if (store_reg(rs1, rdv, regs))
			return -1;
		regs->y = rs2;
		break;
	case 11: /* smul */
#ifdef DEBUG_MULDIV
		printk ("signed muldiv: 0x%x * 0x%x = ", rs1, rs2);
#endif
		__asm__ __volatile__ ("\n\t"
			"mov	%0, %%o0\n\t"
			"call	.mul\n\t"
			" mov	%1, %%o1\n\t"
			"mov	%%o0, %0\n\t"
			"mov	%%o1, %1\n\t"
			: "=r" (rs1), "=r" (rs2)
		        : "0" (rs1), "1" (rs2)
			: "o0", "o1", "o2", "o3", "o4", "o5", "o7", "cc");
#ifdef DEBUG_MULDIV
		printk ("0x%x%08x\n", rs2, rs1);
#endif
		if (store_reg(rs1, rdv, regs))
			return -1;
		regs->y = rs2;
		break;
	case 14: /* udiv */
#ifdef DEBUG_MULDIV
		printk ("unsigned muldiv: 0x%x%08x / 0x%x = ", regs->y, rs1, rs2);
#endif
		if (!rs2) {
#ifdef DEBUG_MULDIV
			printk ("DIVISION BY ZERO\n");
#endif
			handle_hw_divzero (regs, pc, regs->npc, regs->psr);
			return 0;
		}
		__asm__ __volatile__ ("\n\t"
			"mov	%2, %%o0\n\t"
			"mov	%0, %%o1\n\t"
			"mov	%%g0, %%o2\n\t"
			"call	__udivdi3\n\t"
			" mov	%1, %%o3\n\t"
			"mov	%%o1, %0\n\t"
			"mov	%%o0, %1\n\t"
			: "=r" (rs1), "=r" (rs2)
			: "r" (regs->y), "0" (rs1), "1" (rs2)
			: "o0", "o1", "o2", "o3", "o4", "o5", "o7",
			  "g1", "g2", "g3", "cc");
#ifdef DEBUG_MULDIV
		printk ("0x%x\n", rs1);
#endif
		if (store_reg(rs1, rdv, regs))
			return -1;
		break;
	case 15: /* sdiv */
#ifdef DEBUG_MULDIV
		printk ("signed muldiv: 0x%x%08x / 0x%x = ", regs->y, rs1, rs2);
#endif
		if (!rs2) {
#ifdef DEBUG_MULDIV
			printk ("DIVISION BY ZERO\n");
#endif
			handle_hw_divzero (regs, pc, regs->npc, regs->psr);
			return 0;
		}
		__asm__ __volatile__ ("\n\t"
			"mov	%2, %%o0\n\t"
			"mov	%0, %%o1\n\t"
			"mov	%%g0, %%o2\n\t"
			"call	__divdi3\n\t"
			" mov	%1, %%o3\n\t"
			"mov	%%o1, %0\n\t"
			"mov	%%o0, %1\n\t"
			: "=r" (rs1), "=r" (rs2)
			: "r" (regs->y), "0" (rs1), "1" (rs2)
			: "o0", "o1", "o2", "o3", "o4", "o5", "o7",
			  "g1", "g2", "g3", "cc");
#ifdef DEBUG_MULDIV
		printk ("0x%x\n", rs1);
#endif
		if (store_reg(rs1, rdv, regs))
			return -1;
		break;
	}
	if (is_foocc (insn)) {
		regs->psr &= ~PSR_ICC;
		if ((inst & 0xe) == 14) {
			/* ?div */
			if (rs2) regs->psr |= PSR_V;
		}
		if (!rs1) regs->psr |= PSR_Z;
		if (((int)rs1) < 0) regs->psr |= PSR_N;
#ifdef DEBUG_MULDIV
		printk ("psr muldiv: %08x\n", regs->psr);
#endif
	}
	advance(regs);
	return 0;
}