[MIPS] Make validator allow only two load patterns via $t8

src/trusted/validator_mips/testdata/test_tp_access.S

+# Copyright 2015 The Native Client Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Several test cases are implemented in this file:
+#  1. Test if regular way to access thread pointers is allowed.
+#  2. Test different random examples of forbidden stores through $t8.
+#  3. Test different random examples of forbidden loads through $t8.
+
+
+   .align 4
+   .globl __start
+__start:
+   .set noreorder
+   .set mips32r2
+
+   # Test valid tp access
+valid_load_access:
+   lw      $a0, 0($t8)            # OK
+   lw      $a0, 4($t8)            # OK
+   nop
+   nop
+
+   # Test invalid tp access
+invalid_store_access:
+   sb      $a0, 4($t8)            # Error, forbidden thread pointer access.
+   sc      $a0, 4($t8)            # Error, forbidden thread pointer access.
+   sdc1    $0, 4($t8)             # Error, forbidden thread pointer access.
+   sdc2    $8, 4($t8)             # Error, forbidden thread pointer access.
+
+   sh      $a0, 4($t8)            # Error, forbidden thread pointer access.
+   sw      $a0, 4($t8)            # Error, forbidden thread pointer access.
+   swc1    $f2, 4($t8)            # Error, forbidden thread pointer access.
+   swc2    $22, 4($t8)            # Error, forbidden thread pointer access.
+
+   swl     $a0, 4($t8)            # Error, forbidden thread pointer access.
+   swr     $a0, 4($t8)            # Error, forbidden thread pointer access.
+   sdxc1   $f6, $a2($t8)          # Error, forbidden instruction.
+   suxc1   $f4, $t8($t8)          # Error, forbidden instruction.
+
+   swxc1   $f4, $t8($t8)          # Error, forbidden instruction.
+   nop
+   nop
+   nop
+
+invalid_load_access:
+   lb      $a0, 4($t8)            # Error, forbidden thread pointer access.
+   lw      $a0, 8($t8)            # Error, forbidden thread pointer access.
+   lbu     $a0, 4($t8)            # Error, forbidden thread pointer access.
+   ldc1    $f0, 4($t8)            # Error, forbidden thread pointer access.
+
+   ldc2    $10, -24($t8)          # Error, forbidden thread pointer access.
+   lh      $a0, 4($t8)            # Error, forbidden thread pointer access.
+   lhu     $a0, 4($t8)            # Error, forbidden thread pointer access.
+   ll      $a0, 4($t8)            # Error, forbidden thread pointer access.
+
+   lwc1    $f0, 4($t8)            # Error, forbidden thread pointer access.
+   lwc2    $10, 4($t8)            # Error, forbidden thread pointer access.
+   lwl     $a0, 4($t8)            # Error, forbidden thread pointer access.
+   lwr     $a0, 4($t8)            # Error, forbidden thread pointer access.
+
+   ldxc1   $f0, $0($t8)           # Error, forbidden instruction.
+   luxc1   $f0, $a2($t8)          # Error, forbidden instruction.
+   lwxc1   $f6, $v0($t8)          # Error, forbidden instruction.
+   nop
+
+   .set dsp
+   lbux    $a3, $t2($t8)          # Error, forbidden instruction.
+   lhx     $a1, $a2($t8)          # Error, forbidden instruction.
+   lwx     $t1, $t2($t8)          # Error, forbidden instruction.
+   nop
+end_of_code: