1 /*
2 * Software emulation of some PPC instructions for the 8xx core.
3 *
4 * Copyright (C) 1998 Dan Malek (dmalek@jlc.net)
5 *
6 * Software floating emuation for the MPC8xx processor. I did this mostly
7 * because it was easier than trying to get the libraries compiled for
8 * software floating point. The goal is still to get the libraries done,
9 * but I lost patience and needed some hacks to at least get init and
10 * shells running. The first problem is the setjmp/longjmp that save
11 * and restore the floating point registers.
12 *
13 * For this emulation, our working registers are found on the register
14 * save area.
15 */
16
17 #include <linux/errno.h>
18 #include <linux/sched.h>
19 #include <linux/kernel.h>
20 #include <linux/mm.h>
21 #include <linux/stddef.h>
22 #include <linux/unistd.h>
23 #include <linux/ptrace.h>
24 #include <linux/slab.h>
25 #include <linux/user.h>
26 #include <linux/a.out.h>
27 #include <linux/interrupt.h>
28
29 #include <asm/pgtable.h>
30 #include <asm/uaccess.h>
31 #include <asm/system.h>
32 #include <asm/io.h>
33 #include <asm/processor.h>
34
35 extern void
36 print_8xx_pte(struct mm_struct *mm, unsigned long addr);
37 extern int
38 get_8xx_pte(struct mm_struct *mm, unsigned long addr);
39
40 /* Eventually we may need a look-up table, but this works for now.
41 */
42 #define LFS 48
43 #define LFD 50
44 #define LFDU 51
45 #define STFD 54
46 #define STFDU 55
47 #define FMR 63
48
49 /*
50 * We return 0 on success, 1 on unimplemented instruction, and EFAULT
51 * if a load/store faulted.
52 */
53 int
Soft_emulate_8xx(struct pt_regs * regs)54 Soft_emulate_8xx(struct pt_regs *regs)
55 {
56 uint inst, instword;
57 uint flreg, idxreg, disp;
58 uint retval;
59 signed short sdisp;
60 uint *ea, *ip;
61
62 retval = 0;
63
64 instword = *((uint *)regs->nip);
65 inst = instword >> 26;
66
67 flreg = (instword >> 21) & 0x1f;
68 idxreg = (instword >> 16) & 0x1f;
69 disp = instword & 0xffff;
70
71 ea = (uint *)(regs->gpr[idxreg] + disp);
72 ip = (uint *)¤t->thread.fpr[flreg];
73
74 switch ( inst )
75 {
76 case LFD:
77 /* this is a 16 bit quantity that is sign extended
78 * so use a signed short here -- Cort
79 */
80 sdisp = (instword & 0xffff);
81 ea = (uint *)(regs->gpr[idxreg] + sdisp);
82 if (copy_from_user(ip, ea, sizeof(double)))
83 retval = -EFAULT;
84 break;
85
86 case LFDU:
87 if (copy_from_user(ip, ea, sizeof(double)))
88 retval = -EFAULT;
89 else
90 regs->gpr[idxreg] = (uint)ea;
91 break;
92 case LFS:
93 sdisp = (instword & 0xffff);
94 ea = (uint *)(regs->gpr[idxreg] + sdisp);
95 if (copy_from_user(ip, ea, sizeof(float)))
96 retval = -EFAULT;
97 break;
98 case STFD:
99 /* this is a 16 bit quantity that is sign extended
100 * so use a signed short here -- Cort
101 */
102 sdisp = (instword & 0xffff);
103 ea = (uint *)(regs->gpr[idxreg] + sdisp);
104 if (copy_to_user(ea, ip, sizeof(double)))
105 retval = -EFAULT;
106 break;
107
108 case STFDU:
109 if (copy_to_user(ea, ip, sizeof(double)))
110 retval = -EFAULT;
111 else
112 regs->gpr[idxreg] = (uint)ea;
113 break;
114 case FMR:
115 /* assume this is a fp move -- Cort */
116 memcpy( ip, ¤t->thread.fpr[(instword>>11)&0x1f],
117 sizeof(double) );
118 break;
119 default:
120 retval = 1;
121 printk("Bad emulation %s/%d\n"
122 " NIP: %08lx instruction: %08x opcode: %x "
123 "A: %x B: %x C: %x code: %x rc: %x\n",
124 current->comm,current->pid,
125 regs->nip,
126 instword,inst,
127 (instword>>16)&0x1f,
128 (instword>>11)&0x1f,
129 (instword>>6)&0x1f,
130 (instword>>1)&0x3ff,
131 instword&1);
132 {
133 unsigned long pa;
134 print_8xx_pte(current->mm,regs->nip);
135 pa = (get_8xx_pte(current->mm,regs->nip) & PAGE_MASK)
136 | (regs->nip & ~PAGE_MASK);
137 printk("Kernel VA for NIP 0x%p ", __va(pa));
138 print_8xx_pte(current->mm, (unsigned long)__va(pa));
139 }
140
141 }
142
143 if (retval == 0)
144 regs->nip += 4;
145 return(retval);
146 }
147
148