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 #include "kernel.h"
  21
  22 /* #define DEBUG_MULDIV */
  23
  24 static inline int has_imm13(int insn)
  25 {
  26         return (insn & 0x2000);
  27 }
  28
  29 static inline int is_foocc(int insn)
  30 {
  31         return (insn & 0x800000);
  32 }
  33
  34 static inline int sign_extend_imm13(int imm)
  35 {
  36         return imm << 19 >> 19;
  37 }
  38
  39 static inline void advance(struct pt_regs *regs)
  40 {
  41         regs->pc   = regs->npc;
  42         regs->npc += 4;
  43 }
  44
  45 static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
  46                                        unsigned int rd)
  47 {
  48         if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
  49                 /* Wheee... */
  50                 __asm__ __volatile__("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                                      "save %sp, -0x40, %sp\n\t"
  56                                      "save %sp, -0x40, %sp\n\t"
  57                                      "restore; restore; restore; restore;\n\t"
  58                                      "restore; restore; restore;\n\t");
  59         }
  60 }
  61
  62 #define fetch_reg(reg, regs) ({                                         \
  63         struct reg_window32 __user *win;                                        \
  64         register unsigned long ret;                                     \
  65                                                                         \
  66         if (!(reg)) ret = 0;                                            \
  67         else if ((reg) < 16) {                                          \
  68                 ret = regs->u_regs[(reg)];                              \
  69         } else {                                                        \
  70                 /* Ho hum, the slightly complicated case. */            \
  71                 win = (struct reg_window32 __user *)regs->u_regs[UREG_FP];\
  72                 if (get_user (ret, &win->locals[(reg) - 16])) return -1;\
  73         }                                                               \
  74         ret;                                                            \
  75 })
  76
  77 static inline int
  78 store_reg(unsigned int result, unsigned int reg, struct pt_regs *regs)
  79 {
  80         struct reg_window32 __user *win;
  81
  82         if (!reg)
  83                 return 0;
  84         if (reg < 16) {
  85                 regs->u_regs[reg] = result;
  86                 return 0;
  87         } else {
  88                 /* need to use put_user() in this case: */
  89                 win = (struct reg_window32 __user *) regs->u_regs[UREG_FP];
  90                 return (put_user(result, &win->locals[reg - 16]));
  91         }
  92 }
  93
  94 /* Should return 0 if mul/div emulation succeeded and SIGILL should
  95  * not be issued.
  96  */
  97 int do_user_muldiv(struct pt_regs *regs, unsigned long pc)
  98 {
  99         unsigned int insn;
 100         int inst;
 101         unsigned int rs1, rs2, rdv;
 102
 103         if (!pc)
 104                 return -1; /* This happens to often, I think */
 105         if (get_user (insn, (unsigned int __user *)pc))
 106                 return -1;
 107         if ((insn & 0xc1400000) != 0x80400000)
 108                 return -1;
 109         inst = ((insn >> 19) & 0xf);
 110         if ((inst & 0xe) != 10 && (inst & 0xe) != 14)
 111                 return -1;
 112
 113         /* Now we know we have to do something with umul, smul, udiv or sdiv */
 114         rs1 = (insn >> 14) & 0x1f;
 115         rs2 = insn & 0x1f;
 116         rdv = (insn >> 25) & 0x1f;
 117         if (has_imm13(insn)) {
 118                 maybe_flush_windows(rs1, 0, rdv);
 119                 rs2 = sign_extend_imm13(insn);
 120         } else {
 121                 maybe_flush_windows(rs1, rs2, rdv);
 122                 rs2 = fetch_reg(rs2, regs);
 123         }
 124         rs1 = fetch_reg(rs1, regs);
 125         switch (inst) {
 126         case 10: /* umul */
 127 #ifdef DEBUG_MULDIV
 128                 printk ("unsigned muldiv: 0x%x * 0x%x = ", rs1, rs2);
 129 #endif
 130                 __asm__ __volatile__ ("\n\t"
 131                         "mov    %0, %%o0\n\t"
 132                         "call   .umul\n\t"
 133                         " mov   %1, %%o1\n\t"
 134                         "mov    %%o0, %0\n\t"
 135                         "mov    %%o1, %1\n\t"
 136                         : "=r" (rs1), "=r" (rs2)
 137                         : "0" (rs1), "1" (rs2)
 138                         : "o0", "o1", "o2", "o3", "o4", "o5", "o7", "cc");
 139 #ifdef DEBUG_MULDIV
 140                 printk ("0x%x%08x\n", rs2, rs1);
 141 #endif
 142                 if (store_reg(rs1, rdv, regs))
 143                         return -1;
 144                 regs->y = rs2;
 145                 break;
 146         case 11: /* smul */
 147 #ifdef DEBUG_MULDIV
 148                 printk ("signed muldiv: 0x%x * 0x%x = ", rs1, rs2);
 149 #endif
 150                 __asm__ __volatile__ ("\n\t"
 151                         "mov    %0, %%o0\n\t"
 152                         "call   .mul\n\t"
 153                         " mov   %1, %%o1\n\t"
 154                         "mov    %%o0, %0\n\t"
 155                         "mov    %%o1, %1\n\t"
 156                         : "=r" (rs1), "=r" (rs2)
 157                         : "0" (rs1), "1" (rs2)
 158                         : "o0", "o1", "o2", "o3", "o4", "o5", "o7", "cc");
 159 #ifdef DEBUG_MULDIV
 160                 printk ("0x%x%08x\n", rs2, rs1);
 161 #endif
 162                 if (store_reg(rs1, rdv, regs))
 163                         return -1;
 164                 regs->y = rs2;
 165                 break;
 166         case 14: /* udiv */
 167 #ifdef DEBUG_MULDIV
 168                 printk ("unsigned muldiv: 0x%x%08x / 0x%x = ", regs->y, rs1, rs2);
 169 #endif
 170                 if (!rs2) {
 171 #ifdef DEBUG_MULDIV
 172                         printk ("DIVISION BY ZERO\n");
 173 #endif
 174                         handle_hw_divzero (regs, pc, regs->npc, regs->psr);
 175                         return 0;
 176                 }
 177                 __asm__ __volatile__ ("\n\t"
 178                         "mov    %2, %%o0\n\t"
 179                         "mov    %0, %%o1\n\t"
 180                         "mov    %%g0, %%o2\n\t"
 181                         "call   __udivdi3\n\t"
 182                         " mov   %1, %%o3\n\t"
 183                         "mov    %%o1, %0\n\t"
 184                         "mov    %%o0, %1\n\t"
 185                         : "=r" (rs1), "=r" (rs2)
 186                         : "r" (regs->y), "0" (rs1), "1" (rs2)
 187                         : "o0", "o1", "o2", "o3", "o4", "o5", "o7",
 188                           "g1", "g2", "g3", "cc");
 189 #ifdef DEBUG_MULDIV
 190                 printk ("0x%x\n", rs1);
 191 #endif
 192                 if (store_reg(rs1, rdv, regs))
 193                         return -1;
 194                 break;
 195         case 15: /* sdiv */
 196 #ifdef DEBUG_MULDIV
 197                 printk ("signed muldiv: 0x%x%08x / 0x%x = ", regs->y, rs1, rs2);
 198 #endif
 199                 if (!rs2) {
 200 #ifdef DEBUG_MULDIV
 201                         printk ("DIVISION BY ZERO\n");
 202 #endif
 203                         handle_hw_divzero (regs, pc, regs->npc, regs->psr);
 204                         return 0;
 205                 }
 206                 __asm__ __volatile__ ("\n\t"
 207                         "mov    %2, %%o0\n\t"
 208                         "mov    %0, %%o1\n\t"
 209                         "mov    %%g0, %%o2\n\t"
 210                         "call   __divdi3\n\t"
 211                         " mov   %1, %%o3\n\t"
 212                         "mov    %%o1, %0\n\t"
 213                         "mov    %%o0, %1\n\t"
 214                         : "=r" (rs1), "=r" (rs2)
 215                         : "r" (regs->y), "0" (rs1), "1" (rs2)
 216                         : "o0", "o1", "o2", "o3", "o4", "o5", "o7",
 217                           "g1", "g2", "g3", "cc");
 218 #ifdef DEBUG_MULDIV
 219                 printk ("0x%x\n", rs1);
 220 #endif
 221                 if (store_reg(rs1, rdv, regs))
 222                         return -1;
 223                 break;
 224         }
 225         if (is_foocc (insn)) {
 226                 regs->psr &= ~PSR_ICC;
 227                 if ((inst & 0xe) == 14) {
 228                         /* ?div */
 229                         if (rs2) regs->psr |= PSR_V;
 230                 }
 231                 if (!rs1) regs->psr |= PSR_Z;
 232                 if (((int)rs1) < 0) regs->psr |= PSR_N;
 233 #ifdef DEBUG_MULDIV
 234                 printk ("psr muldiv: %08x\n", regs->psr);
 235 #endif
 236         }
 237         advance(regs);
 238         return 0;
 239 }