LXR linux/arch/powerpc/kernel/softemu8xx.c

   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/user.h>
  25#include <linux/interrupt.h>
  26
  27#include <asm/pgtable.h>
  28#include <asm/uaccess.h>
  29#include <asm/io.h>
  30
  31/* Eventually we may need a look-up table, but this works for now.
  32*/
  33#define LFS     48
  34#define LFD     50
  35#define LFDU    51
  36#define STFD    54
  37#define STFDU   55
  38#define FMR     63
  39
  40void print_8xx_pte(struct mm_struct *mm, unsigned long addr)
  41{
  42        pgd_t *pgd;
  43        pmd_t *pmd;
  44        pte_t *pte;
  45
  46        printk(" pte @ 0x%8lx: ", addr);
  47        pgd = pgd_offset(mm, addr & PAGE_MASK);
  48        if (pgd) {
  49                pmd = pmd_offset(pud_offset(pgd, addr & PAGE_MASK),
  50                                 addr & PAGE_MASK);
  51                if (pmd && pmd_present(*pmd)) {
  52                        pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
  53                        if (pte) {
  54                                printk(" (0x%08lx)->(0x%08lx)->0x%08lx\n",
  55                                        (long)pgd, (long)pte, (long)pte_val(*pte));
  56#define pp ((long)pte_val(*pte))
  57                                printk(" RPN: %05lx PP: %lx SPS: %lx SH: %lx "
  58                                       "CI: %lx v: %lx\n",
  59                                       pp>>12,    /* rpn */
  60                                       (pp>>10)&3, /* pp */
  61                                       (pp>>3)&1, /* small */
  62                                       (pp>>2)&1, /* shared */
  63                                       (pp>>1)&1, /* cache inhibit */
  64                                       pp&1       /* valid */
  65                                       );
  66#undef pp
  67                        }
  68                        else {
  69                                printk("no pte\n");
  70                        }
  71                }
  72                else {
  73                        printk("no pmd\n");
  74                }
  75        }
  76        else {
  77                printk("no pgd\n");
  78        }
  79}
  80
  81int get_8xx_pte(struct mm_struct *mm, unsigned long addr)
  82{
  83        pgd_t *pgd;
  84        pmd_t *pmd;
  85        pte_t *pte;
  86        int retval = 0;
  87
  88        pgd = pgd_offset(mm, addr & PAGE_MASK);
  89        if (pgd) {
  90                pmd = pmd_offset(pud_offset(pgd, addr & PAGE_MASK),
  91                                 addr & PAGE_MASK);
  92                if (pmd && pmd_present(*pmd)) {
  93                        pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
  94                        if (pte) {
  95                                retval = (int)pte_val(*pte);
  96                        }
  97                }
  98        }
  99        return retval;
 100}
 101
 102/*
 103 * We return 0 on success, 1 on unimplemented instruction, and EFAULT
 104 * if a load/store faulted.
 105 */
 106int Soft_emulate_8xx(struct pt_regs *regs)
 107{
 108        u32 inst, instword;
 109        u32 flreg, idxreg, disp;
 110        int retval;
 111        s16 sdisp;
 112        u32 *ea, *ip;
 113
 114        retval = 0;
 115
 116        instword = *((u32 *)regs->nip);
 117        inst = instword >> 26;
 118
 119        flreg = (instword >> 21) & 0x1f;
 120        idxreg = (instword >> 16) & 0x1f;
 121        disp = instword & 0xffff;
 122
 123        ea = (u32 *)(regs->gpr[idxreg] + disp);
 124        ip = (u32 *)&current->thread.TS_FPR(flreg);
 125
 126        switch ( inst )
 127        {
 128        case LFD:
 129                /* this is a 16 bit quantity that is sign extended
 130                 * so use a signed short here -- Cort
 131                 */
 132                sdisp = (instword & 0xffff);
 133                ea = (u32 *)(regs->gpr[idxreg] + sdisp);
 134                if (copy_from_user(ip, ea, sizeof(double)))
 135                        retval = -EFAULT;
 136                break;
 137
 138        case LFDU:
 139                if (copy_from_user(ip, ea, sizeof(double)))
 140                        retval = -EFAULT;
 141                else
 142                        regs->gpr[idxreg] = (u32)ea;
 143                break;
 144        case LFS:
 145                sdisp = (instword & 0xffff);
 146                ea = (u32 *)(regs->gpr[idxreg] + sdisp);
 147                if (copy_from_user(ip, ea, sizeof(float)))
 148                        retval = -EFAULT;
 149                break;
 150        case STFD:
 151                /* this is a 16 bit quantity that is sign extended
 152                 * so use a signed short here -- Cort
 153                 */
 154                sdisp = (instword & 0xffff);
 155                ea = (u32 *)(regs->gpr[idxreg] + sdisp);
 156                if (copy_to_user(ea, ip, sizeof(double)))
 157                        retval = -EFAULT;
 158                break;
 159
 160        case STFDU:
 161                if (copy_to_user(ea, ip, sizeof(double)))
 162                        retval = -EFAULT;
 163                else
 164                        regs->gpr[idxreg] = (u32)ea;
 165                break;
 166        case FMR:
 167                /* assume this is a fp move -- Cort */
 168                memcpy(ip, &current->thread.TS_FPR((instword>>11)&0x1f),
 169                       sizeof(double));
 170                break;
 171        default:
 172                retval = 1;
 173                printk("Bad emulation %s/%d\n"
 174                       " NIP: %08lx instruction: %08x opcode: %x "
 175                       "A: %x B: %x C: %x code: %x rc: %x\n",
 176                       current->comm,current->pid,
 177                       regs->nip,
 178                       instword,inst,
 179                       (instword>>16)&0x1f,
 180                       (instword>>11)&0x1f,
 181                       (instword>>6)&0x1f,
 182                       (instword>>1)&0x3ff,
 183                       instword&1);
 184                {
 185                        int pa;
 186                        print_8xx_pte(current->mm,regs->nip);
 187                        pa = get_8xx_pte(current->mm,regs->nip) & PAGE_MASK;
 188                        pa |= (regs->nip & ~PAGE_MASK);
 189                        pa = (unsigned long)__va(pa);
 190                        printk("Kernel VA for NIP %x ", pa);
 191                        print_8xx_pte(current->mm,pa);
 192                }
 193        }
 194
 195        if (retval == 0)
 196                regs->nip += 4;
 197
 198        return retval;
 199}
 200