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   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/interrupt.h>
  27
  28 #include <asm/pgtable.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/system.h>
  31 #include <asm/io.h>
  32
  33 /* Eventually we may need a look-up table, but this works for now.
  34 */
  35 #define LFS     48
  36 #define LFD     50
  37 #define LFDU    51
  38 #define STFD    54
  39 #define STFDU   55
  40 #define FMR     63
  41
  42 void print_8xx_pte(struct mm_struct *mm, unsigned long addr)
  43 {
  44         pgd_t *pgd;
  45         pmd_t *pmd;
  46         pte_t *pte;
  47
  48         printk(" pte @ 0x%8lx: ", addr);
  49         pgd = pgd_offset(mm, addr & PAGE_MASK);
  50         if (pgd) {
  51                 pmd = pmd_offset(pud_offset(pgd, addr & PAGE_MASK),
  52                                  addr & PAGE_MASK);
  53                 if (pmd && pmd_present(*pmd)) {
  54                         pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
  55                         if (pte) {
  56                                 printk(" (0x%08lx)->(0x%08lx)->0x%08lx\n",
  57                                         (long)pgd, (long)pte, (long)pte_val(*pte));
  58 #define pp ((long)pte_val(*pte))
  59                                 printk(" RPN: %05lx PP: %lx SPS: %lx SH: %lx "
  60                                        "CI: %lx v: %lx\n",
  61                                        pp>>12,    /* rpn */
  62                                        (pp>>10)&3, /* pp */
  63                                        (pp>>3)&1, /* small */
  64                                        (pp>>2)&1, /* shared */
  65                                        (pp>>1)&1, /* cache inhibit */
  66                                        pp&1       /* valid */
  67                                        );
  68 #undef pp
  69                         }
  70                         else {
  71                                 printk("no pte\n");
  72                         }
  73                 }
  74                 else {
  75                         printk("no pmd\n");
  76                 }
  77         }
  78         else {
  79                 printk("no pgd\n");
  80         }
  81 }
  82
  83 int get_8xx_pte(struct mm_struct *mm, unsigned long addr)
  84 {
  85         pgd_t *pgd;
  86         pmd_t *pmd;
  87         pte_t *pte;
  88         int retval = 0;
  89
  90         pgd = pgd_offset(mm, addr & PAGE_MASK);
  91         if (pgd) {
  92                 pmd = pmd_offset(pud_offset(pgd, addr & PAGE_MASK),
  93                                  addr & PAGE_MASK);
  94                 if (pmd && pmd_present(*pmd)) {
  95                         pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
  96                         if (pte) {
  97                                 retval = (int)pte_val(*pte);
  98                         }
  99                 }
 100         }
 101         return retval;
 102 }
 103
 104 /*
 105  * We return 0 on success, 1 on unimplemented instruction, and EFAULT
 106  * if a load/store faulted.
 107  */
 108 int Soft_emulate_8xx(struct pt_regs *regs)
 109 {
 110         u32 inst, instword;
 111         u32 flreg, idxreg, disp;
 112         int retval;
 113         s16 sdisp;
 114         u32 *ea, *ip;
 115
 116         retval = 0;
 117
 118         instword = *((u32 *)regs->nip);
 119         inst = instword >> 26;
 120
 121         flreg = (instword >> 21) & 0x1f;
 122         idxreg = (instword >> 16) & 0x1f;
 123         disp = instword & 0xffff;
 124
 125         ea = (u32 *)(regs->gpr[idxreg] + disp);
 126         ip = (u32 *)&current->thread.TS_FPR(flreg);
 127
 128         switch ( inst )
 129         {
 130         case LFD:
 131                 /* this is a 16 bit quantity that is sign extended
 132                  * so use a signed short here -- Cort
 133                  */
 134                 sdisp = (instword & 0xffff);
 135                 ea = (u32 *)(regs->gpr[idxreg] + sdisp);
 136                 if (copy_from_user(ip, ea, sizeof(double)))
 137                         retval = -EFAULT;
 138                 break;
 139
 140         case LFDU:
 141                 if (copy_from_user(ip, ea, sizeof(double)))
 142                         retval = -EFAULT;
 143                 else
 144                         regs->gpr[idxreg] = (u32)ea;
 145                 break;
 146         case LFS:
 147                 sdisp = (instword & 0xffff);
 148                 ea = (u32 *)(regs->gpr[idxreg] + sdisp);
 149                 if (copy_from_user(ip, ea, sizeof(float)))
 150                         retval = -EFAULT;
 151                 break;
 152         case STFD:
 153                 /* this is a 16 bit quantity that is sign extended
 154                  * so use a signed short here -- Cort
 155                  */
 156                 sdisp = (instword & 0xffff);
 157                 ea = (u32 *)(regs->gpr[idxreg] + sdisp);
 158                 if (copy_to_user(ea, ip, sizeof(double)))
 159                         retval = -EFAULT;
 160                 break;
 161
 162         case STFDU:
 163                 if (copy_to_user(ea, ip, sizeof(double)))
 164                         retval = -EFAULT;
 165                 else
 166                         regs->gpr[idxreg] = (u32)ea;
 167                 break;
 168         case FMR:
 169                 /* assume this is a fp move -- Cort */
 170                 memcpy(ip, &current->thread.TS_FPR((instword>>11)&0x1f),
 171                        sizeof(double));
 172                 break;
 173         default:
 174                 retval = 1;
 175                 printk("Bad emulation %s/%d\n"
 176                        " NIP: %08lx instruction: %08x opcode: %x "
 177                        "A: %x B: %x C: %x code: %x rc: %x\n",
 178                        current->comm,current->pid,
 179                        regs->nip,
 180                        instword,inst,
 181                        (instword>>16)&0x1f,
 182                        (instword>>11)&0x1f,
 183                        (instword>>6)&0x1f,
 184                        (instword>>1)&0x3ff,
 185                        instword&1);
 186                 {
 187                         int pa;
 188                         print_8xx_pte(current->mm,regs->nip);
 189                         pa = get_8xx_pte(current->mm,regs->nip) & PAGE_MASK;
 190                         pa |= (regs->nip & ~PAGE_MASK);
 191                         pa = (unsigned long)__va(pa);
 192                         printk("Kernel VA for NIP %x ", pa);
 193                         print_8xx_pte(current->mm,pa);
 194                 }
 195         }
 196
 197         if (retval == 0)
 198                 regs->nip += 4;
 199
 200         return retval;
 201 }