arch/sparc/kernel/muldiv.c

   1 /*
   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  * 2004-12-25   Krzysztof Helt (krzysztof.h1@wp.pl)
   9  *              - fixed registers constrains in inline assembly declarations
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/sched.h>
  14 #include <linux/mm.h>
  15 #include <asm/ptrace.h>
  16 #include <asm/processor.h>
  17 #include <asm/system.h>
  18 #include <asm/uaccess.h>
  19
  20 /* #define DEBUG_MULDIV */
  21
  22 static inline int has_imm13(int insn)
  23 {
  24         return (insn & 0x2000);
  25 }
  26
  27 static inline int is_foocc(int insn)
  28 {
  29         return (insn & 0x800000);
  30 }
  31
  32 static inline int sign_extend_imm13(int imm)
  33 {
  34         return imm << 19 >> 19;
  35 }
  36
  37 static inline void advance(struct pt_regs *regs)
  38 {
  39         regs->pc   = regs->npc;
  40         regs->npc += 4;
  41 }
  42
  43 static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
  44                                        unsigned int rd)
  45 {
  46         if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
  47                 /* Wheee... */
  48                 __asm__ __volatile__("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                                      "save %sp, -0x40, %sp\n\t"
  53                                      "save %sp, -0x40, %sp\n\t"
  54                                      "save %sp, -0x40, %sp\n\t"
  55                                      "restore; restore; restore; restore;\n\t"
  56                                      "restore; restore; restore;\n\t");
  57         }
  58 }
  59
  60 #define fetch_reg(reg, regs) ({                                         \
  61         struct reg_window __user *win;                                  \
  62         register unsigned long ret;                                     \
  63                                                                         \
  64         if (!(reg)) ret = 0;                                            \
  65         else if ((reg) < 16) {                                          \
  66                 ret = regs->u_regs[(reg)];                              \
  67         } else {                                                        \
  68                 /* Ho hum, the slightly complicated case. */            \
  69                 win = (struct reg_window __user *)regs->u_regs[UREG_FP];\
  70                 if (get_user (ret, &win->locals[(reg) - 16])) return -1;\
  71         }                                                               \
  72         ret;                                                            \
  73 })
  74
  75 static inline int
  76 store_reg(unsigned int result, unsigned int reg, struct pt_regs *regs)
  77 {
  78         struct reg_window __user *win;
  79
  80         if (!reg)
  81                 return 0;
  82         if (reg < 16) {
  83                 regs->u_regs[reg] = result;
  84                 return 0;
  85         } else {
  86                 /* need to use put_user() in this case: */
  87                 win = (struct reg_window __user *) regs->u_regs[UREG_FP];
  88                 return (put_user(result, &win->locals[reg - 16]));
  89         }
  90 }
  91
  92 extern void handle_hw_divzero (struct pt_regs *regs, unsigned long pc,
  93                                unsigned long npc, unsigned long psr);
  94
  95 /* Should return 0 if mul/div emulation succeeded and SIGILL should
  96  * not be issued.
  97  */
  98 int do_user_muldiv(struct pt_regs *regs, unsigned long pc)
  99 {
 100         unsigned int insn;
 101         int inst;
 102         unsigned int rs1, rs2, rdv;
 103
 104         if (!pc)
 105                 return -1; /* This happens to often, I think */
 106         if (get_user (insn, (unsigned int __user *)pc))
 107                 return -1;
 108         if ((insn & 0xc1400000) != 0x80400000)
 109                 return -1;
 110         inst = ((insn >> 19) & 0xf);
 111         if ((inst & 0xe) != 10 && (inst & 0xe) != 14)
 112                 return -1;
 113
 114         /* Now we know we have to do something with umul, smul, udiv or sdiv */
 115         rs1 = (insn >> 14) & 0x1f;
 116         rs2 = insn & 0x1f;
 117         rdv = (insn >> 25) & 0x1f;
 118         if (has_imm13(insn)) {
 119                 maybe_flush_windows(rs1, 0, rdv);
 120                 rs2 = sign_extend_imm13(insn);
 121         } else {
 122                 maybe_flush_windows(rs1, rs2, rdv);
 123                 rs2 = fetch_reg(rs2, regs);
 124         }
 125         rs1 = fetch_reg(rs1, regs);
 126         switch (inst) {
 127         case 10: /* umul */
 128 #ifdef DEBUG_MULDIV
 129                 printk ("unsigned muldiv: 0x%x * 0x%x = ", rs1, rs2);
 130 #endif
 131                 __asm__ __volatile__ ("\n\t"
 132                         "mov    %0, %%o0\n\t"
 133                         "call   .umul\n\t"
 134                         " mov   %1, %%o1\n\t"
 135                         "mov    %%o0, %0\n\t"
 136                         "mov    %%o1, %1\n\t"
 137                         : "=r" (rs1), "=r" (rs2)
 138                         : "0" (rs1), "1" (rs2)
 139                         : "o0", "o1", "o2", "o3", "o4", "o5", "o7", "cc");
 140 #ifdef DEBUG_MULDIV
 141                 printk ("0x%x%08x\n", rs2, rs1);
 142 #endif
 143                 if (store_reg(rs1, rdv, regs))
 144                         return -1;
 145                 regs->y = rs2;
 146                 break;
 147         case 11: /* smul */
 148 #ifdef DEBUG_MULDIV
 149                 printk ("signed muldiv: 0x%x * 0x%x = ", rs1, rs2);
 150 #endif
 151                 __asm__ __volatile__ ("\n\t"
 152                         "mov    %0, %%o0\n\t"
 153                         "call   .mul\n\t"
 154                         " mov   %1, %%o1\n\t"
 155                         "mov    %%o0, %0\n\t"
 156                         "mov    %%o1, %1\n\t"
 157                         : "=r" (rs1), "=r" (rs2)
 158                         : "0" (rs1), "1" (rs2)
 159                         : "o0", "o1", "o2", "o3", "o4", "o5", "o7", "cc");
 160 #ifdef DEBUG_MULDIV
 161                 printk ("0x%x%08x\n", rs2, rs1);
 162 #endif
 163                 if (store_reg(rs1, rdv, regs))
 164                         return -1;
 165                 regs->y = rs2;
 166                 break;
 167         case 14: /* udiv */
 168 #ifdef DEBUG_MULDIV
 169                 printk ("unsigned muldiv: 0x%x%08x / 0x%x = ", regs->y, rs1, rs2);
 170 #endif
 171                 if (!rs2) {
 172 #ifdef DEBUG_MULDIV
 173                         printk ("DIVISION BY ZERO\n");
 174 #endif
 175                         handle_hw_divzero (regs, pc, regs->npc, regs->psr);
 176                         return 0;
 177                 }
 178                 __asm__ __volatile__ ("\n\t"
 179                         "mov    %2, %%o0\n\t"
 180                         "mov    %0, %%o1\n\t"
 181                         "mov    %%g0, %%o2\n\t"
 182                         "call   __udivdi3\n\t"
 183                         " mov   %1, %%o3\n\t"
 184                         "mov    %%o1, %0\n\t"
 185                         "mov    %%o0, %1\n\t"
 186                         : "=r" (rs1), "=r" (rs2)
 187                         : "r" (regs->y), "0" (rs1), "1" (rs2)
 188                         : "o0", "o1", "o2", "o3", "o4", "o5", "o7",
 189                           "g1", "g2", "g3", "cc");
 190 #ifdef DEBUG_MULDIV
 191                 printk ("0x%x\n", rs1);
 192 #endif
 193                 if (store_reg(rs1, rdv, regs))
 194                         return -1;
 195                 break;
 196         case 15: /* sdiv */
 197 #ifdef DEBUG_MULDIV
 198                 printk ("signed muldiv: 0x%x%08x / 0x%x = ", regs->y, rs1, rs2);
 199 #endif
 200                 if (!rs2) {
 201 #ifdef DEBUG_MULDIV
 202                         printk ("DIVISION BY ZERO\n");
 203 #endif
 204                         handle_hw_divzero (regs, pc, regs->npc, regs->psr);
 205                         return 0;
 206                 }
 207                 __asm__ __volatile__ ("\n\t"
 208                         "mov    %2, %%o0\n\t"
 209                         "mov    %0, %%o1\n\t"
 210                         "mov    %%g0, %%o2\n\t"
 211                         "call   __divdi3\n\t"
 212                         " mov   %1, %%o3\n\t"
 213                         "mov    %%o1, %0\n\t"
 214                         "mov    %%o0, %1\n\t"
 215                         : "=r" (rs1), "=r" (rs2)
 216                         : "r" (regs->y), "0" (rs1), "1" (rs2)
 217                         : "o0", "o1", "o2", "o3", "o4", "o5", "o7",
 218                           "g1", "g2", "g3", "cc");
 219 #ifdef DEBUG_MULDIV
 220                 printk ("0x%x\n", rs1);
 221 #endif
 222                 if (store_reg(rs1, rdv, regs))
 223                         return -1;
 224                 break;
 225         }
 226         if (is_foocc (insn)) {
 227                 regs->psr &= ~PSR_ICC;
 228                 if ((inst & 0xe) == 14) {
 229                         /* ?div */
 230                         if (rs2) regs->psr |= PSR_V;
 231                 }
 232                 if (!rs1) regs->psr |= PSR_Z;
 233                 if (((int)rs1) < 0) regs->psr |= PSR_N;
 234 #ifdef DEBUG_MULDIV
 235                 printk ("psr muldiv: %08x\n", regs->psr);
 236 #endif
 237         }
 238         advance(regs);
 239         return 0;
 240 }