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