arch/ia64/kernel/brl_emu.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  Emulation of the "brl" instruction for IA64 processors that
   4  *  don't support it in hardware.
   5  *  Author: Stephan Zeisset, Intel Corp. <[email protected]>
   6  *
   7  *    02/22/02  D. Mosberger    Clear si_flgs, si_isr, and si_imm to avoid
   8  *                              leaking kernel bits.
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/sched/signal.h>
  13 #include <linux/uaccess.h>
  14 #include <asm/processor.h>
  15
  16 extern char ia64_set_b1, ia64_set_b2, ia64_set_b3, ia64_set_b4, ia64_set_b5;
  17
  18 struct illegal_op_return {
  19         unsigned long fkt, arg1, arg2, arg3;
  20 };
  21
  22 /*
  23  *  The unimplemented bits of a virtual address must be set
  24  *  to the value of the most significant implemented bit.
  25  *  unimpl_va_mask includes all unimplemented bits and
  26  *  the most significant implemented bit, so the result
  27  *  of an and operation with the mask must be all 0's
  28  *  or all 1's for the address to be valid.
  29  */
  30 #define unimplemented_virtual_address(va) (                                             \
  31         ((va) & local_cpu_data->unimpl_va_mask) != 0 &&                                 \
  32         ((va) & local_cpu_data->unimpl_va_mask) != local_cpu_data->unimpl_va_mask       \
  33 )
  34
  35 /*
  36  *  The unimplemented bits of a physical address must be 0.
  37  *  unimpl_pa_mask includes all unimplemented bits, so the result
  38  *  of an and operation with the mask must be all 0's for the
  39  *  address to be valid.
  40  */
  41 #define unimplemented_physical_address(pa) (            \
  42         ((pa) & local_cpu_data->unimpl_pa_mask) != 0    \
  43 )
  44
  45 /*
  46  *  Handle an illegal operation fault that was caused by an
  47  *  unimplemented "brl" instruction.
  48  *  If we are not successful (e.g because the illegal operation
  49  *  wasn't caused by a "brl" after all), we return -1.
  50  *  If we are successful, we return either 0 or the address
  51  *  of a "fixup" function for manipulating preserved register
  52  *  state.
  53  */
  54
  55 struct illegal_op_return
  56 ia64_emulate_brl (struct pt_regs *regs, unsigned long ar_ec)
  57 {
  58         unsigned long bundle[2];
  59         unsigned long opcode, btype, qp, offset, cpl;
  60         unsigned long next_ip;
  61         struct illegal_op_return rv;
  62         long tmp_taken, unimplemented_address;
  63
  64         rv.fkt = (unsigned long) -1;
  65
  66         /*
  67          *  Decode the instruction bundle.
  68          */
  69
  70         if (copy_from_user(bundle, (void *) (regs->cr_iip), sizeof(bundle)))
  71                 return rv;
  72
  73         next_ip = (unsigned long) regs->cr_iip + 16;
  74
  75         /* "brl" must be in slot 2. */
  76         if (ia64_psr(regs)->ri != 1) return rv;
  77
  78         /* Must be "mlx" template */
  79         if ((bundle[0] & 0x1e) != 0x4) return rv;
  80
  81         opcode = (bundle[1] >> 60);
  82         btype = ((bundle[1] >> 29) & 0x7);
  83         qp = ((bundle[1] >> 23) & 0x3f);
  84         offset = ((bundle[1] & 0x0800000000000000L) << 4)
  85                 | ((bundle[1] & 0x00fffff000000000L) >> 32)
  86                 | ((bundle[1] & 0x00000000007fffffL) << 40)
  87                 | ((bundle[0] & 0xffff000000000000L) >> 24);
  88
  89         tmp_taken = regs->pr & (1L << qp);
  90
  91         switch(opcode) {
  92
  93                 case 0xC:
  94                         /*
  95                          *  Long Branch.
  96                          */
  97                         if (btype != 0) return rv;
  98                         rv.fkt = 0;
  99                         if (!(tmp_taken)) {
 100                                 /*
 101                                  *  Qualifying predicate is 0.
 102                                  *  Skip instruction.
 103                                  */
 104                                 regs->cr_iip = next_ip;
 105                                 ia64_psr(regs)->ri = 0;
 106                                 return rv;
 107                         }
 108                         break;
 109
 110                 case 0xD:
 111                         /*
 112                          *  Long Call.
 113                          */
 114                         rv.fkt = 0;
 115                         if (!(tmp_taken)) {
 116                                 /*
 117                                  *  Qualifying predicate is 0.
 118                                  *  Skip instruction.
 119                                  */
 120                                 regs->cr_iip = next_ip;
 121                                 ia64_psr(regs)->ri = 0;
 122                                 return rv;
 123                         }
 124
 125                         /*
 126                          *  BR[btype] = IP+16
 127                          */
 128                         switch(btype) {
 129                                 case 0:
 130                                         regs->b0 = next_ip;
 131                                         break;
 132                                 case 1:
 133                                         rv.fkt = (unsigned long) &ia64_set_b1;
 134                                         break;
 135                                 case 2:
 136                                         rv.fkt = (unsigned long) &ia64_set_b2;
 137                                         break;
 138                                 case 3:
 139                                         rv.fkt = (unsigned long) &ia64_set_b3;
 140                                         break;
 141                                 case 4:
 142                                         rv.fkt = (unsigned long) &ia64_set_b4;
 143                                         break;
 144                                 case 5:
 145                                         rv.fkt = (unsigned long) &ia64_set_b5;
 146                                         break;
 147                                 case 6:
 148                                         regs->b6 = next_ip;
 149                                         break;
 150                                 case 7:
 151                                         regs->b7 = next_ip;
 152                                         break;
 153                         }
 154                         rv.arg1 = next_ip;
 155
 156                         /*
 157                          *  AR[PFS].pfm = CFM
 158                          *  AR[PFS].pec = AR[EC]
 159                          *  AR[PFS].ppl = PSR.cpl
 160                          */
 161                         cpl = ia64_psr(regs)->cpl;
 162                         regs->ar_pfs = ((regs->cr_ifs & 0x3fffffffff)
 163                                         | (ar_ec << 52) | (cpl << 62));
 164
 165                         /*
 166                          *  CFM.sof -= CFM.sol
 167                          *  CFM.sol = 0
 168                          *  CFM.sor = 0
 169                          *  CFM.rrb.gr = 0
 170                          *  CFM.rrb.fr = 0
 171                          *  CFM.rrb.pr = 0
 172                          */
 173                         regs->cr_ifs = ((regs->cr_ifs & 0xffffffc00000007f)
 174                                         - ((regs->cr_ifs >> 7) & 0x7f));
 175
 176                         break;
 177
 178                 default:
 179                         /*
 180                          *  Unknown opcode.
 181                          */
 182                         return rv;
 183
 184         }
 185
 186         regs->cr_iip += offset;
 187         ia64_psr(regs)->ri = 0;
 188
 189         if (ia64_psr(regs)->it == 0)
 190                 unimplemented_address = unimplemented_physical_address(regs->cr_iip);
 191         else
 192                 unimplemented_address = unimplemented_virtual_address(regs->cr_iip);
 193
 194         if (unimplemented_address) {
 195                 /*
 196                  *  The target address contains unimplemented bits.
 197                  */
 198                 printk(KERN_DEBUG "Woah! Unimplemented Instruction Address Trap!\n");
 199                 force_sig_fault(SIGILL, ILL_BADIADDR, (void __user *)NULL,
 200                                 0, 0, 0);
 201         } else if (ia64_psr(regs)->tb) {
 202                 /*
 203                  *  Branch Tracing is enabled.
 204                  *  Force a taken branch signal.
 205                  */
 206                 force_sig_fault(SIGTRAP, TRAP_BRANCH, (void __user *)NULL,
 207                                 0, 0, 0);
 208         } else if (ia64_psr(regs)->ss) {
 209                 /*
 210                  *  Single Step is enabled.
 211                  *  Force a trace signal.
 212                  */
 213                 force_sig_fault(SIGTRAP, TRAP_TRACE, (void __user *)NULL,
 214                                 0, 0, 0);
 215         }
 216         return rv;
 217 }