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/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 /* Eventually we may need a look-up table, but this works for now.
  35 */
  36 #define LFS     48
  37 #define LFD     50
  38 #define LFDU    51
  39 #define STFD    54
  40 #define STFDU   55
  41 #define FMR     63
  42
  43 void print_8xx_pte(struct mm_struct *mm, unsigned long addr)
  44 {
  45         pgd_t *pgd;
  46         pmd_t *pmd;
  47         pte_t *pte;
  48
  49         printk(" pte @ 0x%8lx: ", addr);
  50         pgd = pgd_offset(mm, addr & PAGE_MASK);
  51         if (pgd) {
  52                 pmd = pmd_offset(pud_offset(pgd, addr & PAGE_MASK),
  53                                  addr & PAGE_MASK);
  54                 if (pmd && pmd_present(*pmd)) {
  55                         pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
  56                         if (pte) {
  57                                 printk(" (0x%08lx)->(0x%08lx)->0x%08lx\n",
  58                                         (long)pgd, (long)pte, (long)pte_val(*pte));
  59 #define pp ((long)pte_val(*pte))
  60                                 printk(" RPN: %05lx PP: %lx SPS: %lx SH: %lx "
  61                                        "CI: %lx v: %lx\n",
  62                                        pp>>12,    /* rpn */
  63                                        (pp>>10)&3, /* pp */
  64                                        (pp>>3)&1, /* small */
  65                                        (pp>>2)&1, /* shared */
  66                                        (pp>>1)&1, /* cache inhibit */
  67                                        pp&1       /* valid */
  68                                        );
  69 #undef pp
  70                         }
  71                         else {
  72                                 printk("no pte\n");
  73                         }
  74                 }
  75                 else {
  76                         printk("no pmd\n");
  77                 }
  78         }
  79         else {
  80                 printk("no pgd\n");
  81         }
  82 }
  83
  84 int get_8xx_pte(struct mm_struct *mm, unsigned long addr)
  85 {
  86         pgd_t *pgd;
  87         pmd_t *pmd;
  88         pte_t *pte;
  89         int retval = 0;
  90
  91         pgd = pgd_offset(mm, addr & PAGE_MASK);
  92         if (pgd) {
  93                 pmd = pmd_offset(pud_offset(pgd, addr & PAGE_MASK),
  94                                  addr & PAGE_MASK);
  95                 if (pmd && pmd_present(*pmd)) {
  96                         pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
  97                         if (pte) {
  98                                 retval = (int)pte_val(*pte);
  99                         }
 100                 }
 101         }
 102         return retval;
 103 }
 104
 105 /*
 106  * We return 0 on success, 1 on unimplemented instruction, and EFAULT
 107  * if a load/store faulted.
 108  */
 109 int Soft_emulate_8xx(struct pt_regs *regs)
 110 {
 111         u32 inst, instword;
 112         u32 flreg, idxreg, disp;
 113         int retval;
 114         s16 sdisp;
 115         u32 *ea, *ip;
 116
 117         retval = 0;
 118
 119         instword = *((u32 *)regs->nip);
 120         inst = instword >> 26;
 121
 122         flreg = (instword >> 21) & 0x1f;
 123         idxreg = (instword >> 16) & 0x1f;
 124         disp = instword & 0xffff;
 125
 126         ea = (u32 *)(regs->gpr[idxreg] + disp);
 127         ip = (u32 *)&current->thread.TS_FPR(flreg);
 128
 129         switch ( inst )
 130         {
 131         case LFD:
 132                 /* this is a 16 bit quantity that is sign extended
 133                  * so use a signed short here -- Cort
 134                  */
 135                 sdisp = (instword & 0xffff);
 136                 ea = (u32 *)(regs->gpr[idxreg] + sdisp);
 137                 if (copy_from_user(ip, ea, sizeof(double)))
 138                         retval = -EFAULT;
 139                 break;
 140
 141         case LFDU:
 142                 if (copy_from_user(ip, ea, sizeof(double)))
 143                         retval = -EFAULT;
 144                 else
 145                         regs->gpr[idxreg] = (u32)ea;
 146                 break;
 147         case LFS:
 148                 sdisp = (instword & 0xffff);
 149                 ea = (u32 *)(regs->gpr[idxreg] + sdisp);
 150                 if (copy_from_user(ip, ea, sizeof(float)))
 151                         retval = -EFAULT;
 152                 break;
 153         case STFD:
 154                 /* this is a 16 bit quantity that is sign extended
 155                  * so use a signed short here -- Cort
 156                  */
 157                 sdisp = (instword & 0xffff);
 158                 ea = (u32 *)(regs->gpr[idxreg] + sdisp);
 159                 if (copy_to_user(ea, ip, sizeof(double)))
 160                         retval = -EFAULT;
 161                 break;
 162
 163         case STFDU:
 164                 if (copy_to_user(ea, ip, sizeof(double)))
 165                         retval = -EFAULT;
 166                 else
 167                         regs->gpr[idxreg] = (u32)ea;
 168                 break;
 169         case FMR:
 170                 /* assume this is a fp move -- Cort */
 171                 memcpy(ip, &current->thread.TS_FPR((instword>>11)&0x1f),
 172                        sizeof(double));
 173                 break;
 174         default:
 175                 retval = 1;
 176                 printk("Bad emulation %s/%d\n"
 177                        " NIP: %08lx instruction: %08x opcode: %x "
 178                        "A: %x B: %x C: %x code: %x rc: %x\n",
 179                        current->comm,current->pid,
 180                        regs->nip,
 181                        instword,inst,
 182                        (instword>>16)&0x1f,
 183                        (instword>>11)&0x1f,
 184                        (instword>>6)&0x1f,
 185                        (instword>>1)&0x3ff,
 186                        instword&1);
 187                 {
 188                         int pa;
 189                         print_8xx_pte(current->mm,regs->nip);
 190                         pa = get_8xx_pte(current->mm,regs->nip) & PAGE_MASK;
 191                         pa |= (regs->nip & ~PAGE_MASK);
 192                         pa = (unsigned long)__va(pa);
 193                         printk("Kernel VA for NIP %x ", pa);
 194                         print_8xx_pte(current->mm,pa);
 195                 }
 196         }
 197
 198         if (retval == 0)
 199                 regs->nip += 4;
 200
 201         return retval;
 202 }