File: /usr/src/linux/arch/ppc/kernel/softemu8xx.c
1 /*
2 * BK Id: SCCS/s.softemu8xx.c 1.8 05/17/01 18:14:22 cort
3 */
4 /*
5 * Software emulation of some PPC instructions for the 8xx core.
6 *
7 * Copyright (C) 1998 Dan Malek (dmalek@jlc.net)
8 *
9 * Software floating emuation for the MPC8xx processor. I did this mostly
10 * because it was easier than trying to get the libraries compiled for
11 * software floating point. The goal is still to get the libraries done,
12 * but I lost patience and needed some hacks to at least get init and
13 * shells running. The first problem is the setjmp/longjmp that save
14 * and restore the floating point registers.
15 *
16 * For this emulation, our working registers are found on the register
17 * save area.
18 */
19
20 #include <linux/errno.h>
21 #include <linux/sched.h>
22 #include <linux/kernel.h>
23 #include <linux/mm.h>
24 #include <linux/stddef.h>
25 #include <linux/unistd.h>
26 #include <linux/ptrace.h>
27 #include <linux/slab.h>
28 #include <linux/user.h>
29 #include <linux/a.out.h>
30 #include <linux/interrupt.h>
31
32 #include <asm/pgtable.h>
33 #include <asm/uaccess.h>
34 #include <asm/system.h>
35 #include <asm/io.h>
36 #include <asm/processor.h>
37
38 /* Eventually we may need a look-up table, but this works for now.
39 */
40 #define LFS 48
41 #define LFD 50
42 #define LFDU 51
43 #define STFD 54
44 #define STFDU 55
45 #define FMR 63
46
47 /*
48 * We return 0 on success, 1 on unimplemented instruction, and EFAULT
49 * if a load/store faulted.
50 */
51 int
52 Soft_emulate_8xx(struct pt_regs *regs)
53 {
54 uint inst, instword;
55 uint flreg, idxreg, disp;
56 uint retval;
57 signed short sdisp;
58 uint *ea, *ip;
59
60 retval = 0;
61
62 instword = *((uint *)regs->nip);
63 inst = instword >> 26;
64
65 flreg = (instword >> 21) & 0x1f;
66 idxreg = (instword >> 16) & 0x1f;
67 disp = instword & 0xffff;
68
69 ea = (uint *)(regs->gpr[idxreg] + disp);
70 ip = (uint *)¤t->thread.fpr[flreg];
71
72 switch ( inst )
73 {
74 case LFD:
75 /* this is a 16 bit quantity that is sign extended
76 * so use a signed short here -- Cort
77 */
78 sdisp = (instword & 0xffff);
79 ea = (uint *)(regs->gpr[idxreg] + sdisp);
80 if (copy_from_user(ip, ea, sizeof(double)))
81 retval = -EFAULT;
82 break;
83
84 case LFDU:
85 if (copy_from_user(ip, ea, sizeof(double)))
86 retval = -EFAULT;
87 else
88 regs->gpr[idxreg] = (uint)ea;
89 break;
90 case LFS:
91 sdisp = (instword & 0xffff);
92 ea = (uint *)(regs->gpr[idxreg] + sdisp);
93 if (copy_from_user(ip, ea, sizeof(float)))
94 retval = -EFAULT;
95 break;
96 case STFD:
97 /* this is a 16 bit quantity that is sign extended
98 * so use a signed short here -- Cort
99 */
100 sdisp = (instword & 0xffff);
101 ea = (uint *)(regs->gpr[idxreg] + sdisp);
102 if (copy_to_user(ea, ip, sizeof(double)))
103 retval = -EFAULT;
104 break;
105
106 case STFDU:
107 if (copy_to_user(ea, ip, sizeof(double)))
108 retval = -EFAULT;
109 else
110 regs->gpr[idxreg] = (uint)ea;
111 break;
112 case FMR:
113 /* assume this is a fp move -- Cort */
114 memcpy( ip, ¤t->thread.fpr[(instword>>11)&0x1f],
115 sizeof(double) );
116 break;
117 default:
118 retval = 1;
119 printk("Bad emulation %s/%d\n"
120 " NIP: %08x instruction: %08x opcode: %x "
121 "A: %x B: %x C: %x code: %x rc: %x\n",
122 current->comm,current->pid,
123 regs->nip,
124 instword,inst,
125 (instword>>16)&0x1f,
126 (instword>>11)&0x1f,
127 (instword>>6)&0x1f,
128 (instword>>1)&0x3ff,
129 instword&1);
130 {
131 int pa;
132 print_8xx_pte(current->mm,regs->nip);
133 pa = get_8xx_pte(current->mm,regs->nip) & PAGE_MASK;
134 pa |= (regs->nip & ~PAGE_MASK);
135 pa = __va(pa);
136 printk("Kernel VA for NIP %x ", pa);
137 print_8xx_pte(current->mm,pa);
138 }
139
140 }
141
142 if (retval == 0)
143 regs->nip += 4;
144 return(retval);
145 }
146
147