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