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/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
  34 extern void
  35 print_8xx_pte(struct mm_struct *mm, unsigned long addr);
  36 extern int
  37 get_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  */
  52 int
  53 Soft_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