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