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
34extern void
35print_8xx_pte(struct mm_struct *mm, unsigned long addr);
36extern int
37get_8xx_pte(struct mm_struct *mm, unsigned long addr);
38
39/* Eventually we may need a look-up table, but this works for now.
40*/
41#define LFS	48
42#define LFD	50
43#define LFDU	51
44#define STFD	54
45#define STFDU	55
46#define FMR	63
47
48/*
49 * We return 0 on success, 1 on unimplemented instruction, and EFAULT
50 * if a load/store faulted.
51 */
52int
53Soft_emulate_8xx(struct pt_regs *regs)
54{
55	uint	inst, instword;
56	uint	flreg, idxreg, disp;
57	uint	retval;
58	signed short sdisp;
59	uint	*ea, *ip;
60
61	retval = 0;
62
63	instword = *((uint *)regs->nip);
64	inst = instword >> 26;
65
66	flreg = (instword >> 21) & 0x1f;
67	idxreg = (instword >> 16) & 0x1f;
68	disp = instword & 0xffff;
69
70	ea = (uint *)(regs->gpr[idxreg] + disp);
71	ip = (uint *)&current->thread.fpr[flreg];
72
73	switch ( inst )
74	{
75	case LFD:
76		/* this is a 16 bit quantity that is sign extended
77		 * so use a signed short here -- Cort
78		 */
79		sdisp = (instword & 0xffff);
80		ea = (uint *)(regs->gpr[idxreg] + sdisp);
81		if (copy_from_user(ip, ea, sizeof(double)))
82			retval = -EFAULT;
83		break;
84
85	case LFDU:
86		if (copy_from_user(ip, ea, sizeof(double)))
87			retval = -EFAULT;
88		else
89			regs->gpr[idxreg] = (uint)ea;
90		break;
91	case LFS:
92		sdisp = (instword & 0xffff);
93		ea = (uint *)(regs->gpr[idxreg] + sdisp);
94		if (copy_from_user(ip, ea, sizeof(float)))
95			retval = -EFAULT;
96		break;
97	case STFD:
98		/* this is a 16 bit quantity that is sign extended
99		 * so use a signed short here -- Cort
100		 */
101		sdisp = (instword & 0xffff);
102		ea = (uint *)(regs->gpr[idxreg] + sdisp);
103		if (copy_to_user(ea, ip, sizeof(double)))
104			retval = -EFAULT;
105		break;
106
107	case STFDU:
108		if (copy_to_user(ea, ip, sizeof(double)))
109			retval = -EFAULT;
110		else
111			regs->gpr[idxreg] = (uint)ea;
112		break;
113	case FMR:
114		/* assume this is a fp move -- Cort */
115		memcpy( ip, &current->thread.fpr[(instword>>11)&0x1f],
116			sizeof(double) );
117		break;
118	default:
119		retval = 1;
120		printk("Bad emulation %s/%d\n"
121		       " NIP: %08lx instruction: %08x opcode: %x "
122		       "A: %x B: %x C: %x code: %x rc: %x\n",
123		       current->comm,current->pid,
124		       regs->nip,
125		       instword,inst,
126		       (instword>>16)&0x1f,
127		       (instword>>11)&0x1f,
128		       (instword>>6)&0x1f,
129		       (instword>>1)&0x3ff,
130		       instword&1);
131		{
132			int pa;
133			print_8xx_pte(current->mm,regs->nip);
134			pa = get_8xx_pte(current->mm,regs->nip) & PAGE_MASK;
135			pa |= (regs->nip & ~PAGE_MASK);
136			pa = (unsigned long)__va(pa);
137			printk("Kernel VA for NIP %x ", pa);
138			print_8xx_pte(current->mm,pa);
139		}
140
141	}
142
143	if (retval == 0)
144		regs->nip += 4;
145	return(retval);
146}
147