arch/sparc/kernel/muldiv.c

   1 /* $Id: muldiv.c,v 1.5 1997/12/15 20:07:20 ecd Exp $
   2  * muldiv.c: Hardware multiply/division illegal instruction trap
   3  *              for sun4c/sun4 (which do not have those instructions)
   4  *
   5  * Copyright (C) 1996 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
   6  * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/sched.h>
  11 #include <linux/mm.h>
  12 #include <asm/ptrace.h>
  13 #include <asm/processor.h>
  14 #include <asm/system.h>
  15 #include <asm/uaccess.h>
  16
  17 /* #define DEBUG_MULDIV */
  18
  19 static inline int has_imm13(int insn)
  20 {
  21         return (insn & 0x2000);
  22 }
  23
  24 static inline int is_foocc(int insn)
  25 {
  26         return (insn & 0x800000);
  27 }
  28
  29 static inline int sign_extend_imm13(int imm)
  30 {
  31         return imm << 19 >> 19;
  32 }
  33
  34 static inline void advance(struct pt_regs *regs)
  35 {
  36         regs->pc   = regs->npc;
  37         regs->npc += 4;
  38 }
  39
  40 static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
  41                                        unsigned int rd)
  42 {
  43         if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
  44                 /* Wheee... */
  45                 __asm__ __volatile__("save %sp, -0x40, %sp\n\t"
  46                                      "save %sp, -0x40, %sp\n\t"
  47                                      "save %sp, -0x40, %sp\n\t"
  48                                      "save %sp, -0x40, %sp\n\t"
  49                                      "save %sp, -0x40, %sp\n\t"
  50                                      "save %sp, -0x40, %sp\n\t"
  51                                      "save %sp, -0x40, %sp\n\t"
  52                                      "restore; restore; restore; restore;\n\t"
  53                                      "restore; restore; restore;\n\t");
  54         }
  55 }
  56
  57 #define fetch_reg(reg, regs) ({                                                 \
  58         struct reg_window *win;                                                 \
  59         register unsigned long ret;                                             \
  60                                                                                 \
  61         if (!(reg)) ret = 0;                                                    \
  62         else if((reg) < 16) {                                                   \
  63                 ret = regs->u_regs[(reg)];                                      \
  64         } else {                                                                \
  65                 /* Ho hum, the slightly complicated case. */                    \
  66                 win = (struct reg_window *)regs->u_regs[UREG_FP];               \
  67                 if (get_user (ret, &win->locals[(reg) - 16])) return -1;        \
  68         }                                                                       \
  69         ret;                                                                    \
  70 })
  71
  72 static inline int
  73 store_reg(unsigned int result, unsigned int reg, struct pt_regs *regs)
  74 {
  75         struct reg_window *win;
  76
  77         if (!reg)
  78                 return 0;
  79         if (reg < 16) {
  80                 regs->u_regs[reg] = result;
  81                 return 0;
  82         } else {
  83                 /* need to use put_user() in this case: */
  84                 win = (struct reg_window *)regs->u_regs[UREG_FP];
  85                 return (put_user(result, &win->locals[reg - 16]));
  86         }
  87 }
  88
  89 extern void handle_hw_divzero (struct pt_regs *regs, unsigned long pc,
  90                                unsigned long npc, unsigned long psr);
  91
  92 /* Should return 0 if mul/div emulation succeeded and SIGILL should not be issued */
  93 int do_user_muldiv(struct pt_regs *regs, unsigned long pc)
  94 {
  95         unsigned int insn;
  96         int inst;
  97         unsigned int rs1, rs2, rdv;
  98
  99         if (!pc) return -1; /* This happens to often, I think */
 100         if (get_user (insn, (unsigned int *)pc)) return -1;
 101         if ((insn & 0xc1400000) != 0x80400000) return -1;
 102         inst = ((insn >> 19) & 0xf);
 103         if ((inst & 0xe) != 10 && (inst & 0xe) != 14) return -1;
 104         /* Now we know we have to do something with umul, smul, udiv or sdiv */
 105         rs1 = (insn >> 14) & 0x1f;
 106         rs2 = insn & 0x1f;
 107         rdv = (insn >> 25) & 0x1f;
 108         if(has_imm13(insn)) {
 109                 maybe_flush_windows(rs1, 0, rdv);
 110                 rs2 = sign_extend_imm13(insn);
 111         } else {
 112                 maybe_flush_windows(rs1, rs2, rdv);
 113                 rs2 = fetch_reg(rs2, regs);
 114         }
 115         rs1 = fetch_reg(rs1, regs);
 116         switch (inst) {
 117         case 10: /* umul */
 118 #ifdef DEBUG_MULDIV
 119                 printk ("unsigned muldiv: 0x%x * 0x%x = ", rs1, rs2);
 120 #endif
 121                 __asm__ __volatile__ ("\n\t"
 122                         "mov    %0, %%o0\n\t"
 123                         "call   .umul\n\t"
 124                         " mov   %1, %%o1\n\t"
 125                         "mov    %%o0, %0\n\t"
 126                         "mov    %%o1, %1\n\t"
 127                         : "=r" (rs1), "=r" (rs2)
 128                         :
 129                         : "o0", "o1", "o2", "o3", "o4", "o5", "o7", "cc");
 130 #ifdef DEBUG_MULDIV
 131                 printk ("0x%x%08x\n", rs2, rs1);
 132 #endif
 133                 if (store_reg(rs1, rdv, regs))
 134                         return -1;
 135                 regs->y = rs2;
 136                 break;
 137         case 11: /* smul */
 138 #ifdef DEBUG_MULDIV
 139                 printk ("signed muldiv: 0x%x * 0x%x = ", rs1, rs2);
 140 #endif
 141                 __asm__ __volatile__ ("\n\t"
 142                         "mov    %0, %%o0\n\t"
 143                         "call   .mul\n\t"
 144                         " mov   %1, %%o1\n\t"
 145                         "mov    %%o0, %0\n\t"
 146                         "mov    %%o1, %1\n\t"
 147                         : "=r" (rs1), "=r" (rs2)
 148                         :
 149                         : "o0", "o1", "o2", "o3", "o4", "o5", "o7", "cc");
 150 #ifdef DEBUG_MULDIV
 151                 printk ("0x%x%08x\n", rs2, rs1);
 152 #endif
 153                 if (store_reg(rs1, rdv, regs))
 154                         return -1;
 155                 regs->y = rs2;
 156                 break;
 157         case 14: /* udiv */
 158 #ifdef DEBUG_MULDIV
 159                 printk ("unsigned muldiv: 0x%x%08x / 0x%x = ", regs->y, rs1, rs2);
 160 #endif
 161                 if (!rs2) {
 162 #ifdef DEBUG_MULDIV
 163                         printk ("DIVISION BY ZERO\n");
 164 #endif
 165                         handle_hw_divzero (regs, pc, regs->npc, regs->psr);
 166                         return 0;
 167                 }
 168                 __asm__ __volatile__ ("\n\t"
 169                         "mov    %2, %%o0\n\t"
 170                         "mov    %0, %%o1\n\t"
 171                         "mov    %%g0, %%o2\n\t"
 172                         "call   __udivdi3\n\t"
 173                         " mov   %1, %%o3\n\t"
 174                         "mov    %%o1, %0\n\t"
 175                         "mov    %%o0, %1\n\t"
 176                         : "=r" (rs1), "=r" (rs2)
 177                         : "r" (regs->y)
 178                         : "o0", "o1", "o2", "o3", "o4", "o5", "o7",
 179                           "g1", "g2", "g3", "cc");
 180 #ifdef DEBUG_MULDIV
 181                 printk ("0x%x\n", rs1);
 182 #endif
 183                 if (store_reg(rs1, rdv, regs))
 184                         return -1;
 185                 break;
 186         case 15: /* sdiv */
 187 #ifdef DEBUG_MULDIV
 188                 printk ("signed muldiv: 0x%x%08x / 0x%x = ", regs->y, rs1, rs2);
 189 #endif
 190                 if (!rs2) {
 191 #ifdef DEBUG_MULDIV
 192                         printk ("DIVISION BY ZERO\n");
 193 #endif
 194                         handle_hw_divzero (regs, pc, regs->npc, regs->psr);
 195                         return 0;
 196                 }
 197                 __asm__ __volatile__ ("\n\t"
 198                         "mov    %2, %%o0\n\t"
 199                         "mov    %0, %%o1\n\t"
 200                         "mov    %%g0, %%o2\n\t"
 201                         "call   __divdi3\n\t"
 202                         " mov   %1, %%o3\n\t"
 203                         "mov    %%o1, %0\n\t"
 204                         "mov    %%o0, %1\n\t"
 205                         : "=r" (rs1), "=r" (rs2)
 206                         : "r" (regs->y)
 207                         : "o0", "o1", "o2", "o3", "o4", "o5", "o7",
 208                           "g1", "g2", "g3", "cc");
 209 #ifdef DEBUG_MULDIV
 210                 printk ("0x%x\n", rs1);
 211 #endif
 212                 if (store_reg(rs1, rdv, regs))
 213                         return -1;
 214                 break;
 215         }
 216         if (is_foocc (insn)) {
 217                 regs->psr &= ~PSR_ICC;
 218                 if ((inst & 0xe) == 14) {
 219                         /* ?div */
 220                         if (rs2) regs->psr |= PSR_V;
 221                 }
 222                 if (!rs1) regs->psr |= PSR_Z;
 223                 if (((int)rs1) < 0) regs->psr |= PSR_N;
 224 #ifdef DEBUG_MULDIV
 225                 printk ("psr muldiv: %08x\n", regs->psr);
 226 #endif
 227         }
 228         advance(regs);
 229         return 0;
 230 }