[MIPS] Adding validator for MIPS architecture.

src/trusted/validator_mips/testdata/test_jmp_imm.S

+# Copyright 2012 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.
+
+# Test cases for jumps/branches.
+# There are several kinds of jumps/branches regarding destination address:
+# 1. Jumps into 0-0x10000, null guard region, where every address is OK.
+# 2. Jumps into 0x10000-0x20000, trampoline code section, destination address
+#    needs to be bundle aligned.
+# 3. Jumps into code section, all addresses are OK with additional check whether
+#    a branch target address is inside of a pseudo-instruction.
+# Besides destination address we also check the position of branch/jump-and-link
+# instructions, which need to be at bundle offset +8.
+
+.globl _start
+_start:
+.align 4
+.set noreorder
+
+   # Branches to null guard region, everything is OK.
+
+bundle_b_to_0_0x1000:
+   b   _start - 0x10010    # Destination address is 0xfff0 - OK.
+    nop                    # Instruction in the delay slot is always indented.
+   b   _start - 0x1fff4    # Destination address is 0xc - OK.
+    nop
+
+   # Branches to trampoline code section, must be bundle aligned.
+
+bundle_b_to_0x1000_0x20000:
+   b   _start - 0x10000    # OK - trampoline start.
+    nop
+   b   _start - 0xfff0     # OK - bundle aligned jump into trampoline.
+    nop
+   b   _start - 0xfff4     # Error, destination address is 0x1000c, which is
+    nop                    # is not bundle aligned.
+   nop
+   nop
+
+   # Branches to code area.
+
+bundle_b_to_code_area:
+   b   _start + 0x1000     # OK
+    nop
+   b   _start + 0x1004     # OK
+    nop
+   b   _start + 0x10       # OK
+    nop
+   b   end_of_code         # OK
+    nop
+
+   # Both jumps are OK, because destinations are in guard region.
+
+bundle_j_to_0_0x1000:
+   j       0x0
+    nop
+   j       0x4
+    nop
+
+   # Direct jumps to trampoline area, must be bundle aligned.
+
+bundle_j_trampoline_area:
+   j       0x10000
+    nop
+   jal     0x10004         # Error - 0x10004 is not a trampoline start.
+    nop
+
+   nop
+   nop
+   jal     0x10010         # OK - not a trampoline start, but there is a halt.
+    nop
+
+   nop
+   nop
+   jal     0x10020         # OK
+    nop
+
+   # Jumps with negative argument.
+
+bundle_j_negative:
+   j       -0x4            # Dest. address 0xffffffc, inside code region - OK.
+    nop
+   j       -0x10           # Dest. address 0xffffff0, inside code region - OK.
+    nop
+
+bundle_1st:
+   and     $a0, $a0, $t7
+bundle_2nd:
+   sw      $ra, 24($a0)
+   addiu   $v0, $v0, 4
+   addiu   $v0, $v1, 0
+
+bl_check:
+   nop
+   nop
+   bal     bundle_1st      # OK
+    nop
+
+   # Branch inside a pseudo-instruction.
+
+bundle_check_b_dest_addr:
+   b       bundle_1st      # OK
+    nop
+   b       bundle_2nd      # Error, branch at the middle of pseudo-instruction.
+    nop
+
+   # Test if branch and link is located at bundle offset 8.
+
+   bal     0x10000         # Error, misaligned call.
+    nop
+   bal     0x10000         # OK
+    nop
+
+   # Test if jump and link is located at bundle offset 8.
+
+   jal     0x10000         # Error, misaligned call.
+    nop
+   jal     0x3fffff0       # OK
+    nop
+
+   # Another branch instruction with the same target address.
+   # Check if this one is also reported.
+
+   b       bundle_2nd      # Error, branch at middle of pseudo-instruction.
+    nop
+
+   # Test forbidden instruction.
+
+   jalx    0x3ffffff0      # Error, forbidden instruction.
+   nop
+
+end_of_code: