svn commit: r283255 - head/sys/amd64/vmm

[Neel Natu]

Author: neel
Date: Thu May 21 18:23:37 2015
New Revision: 283255
URL: https://svnweb.freebsd.org/changeset/base/283255

Log:
  Emulate the "CMP r/m, reg" instruction (opcode 39H).
  
  Reported and tested by:       Leon Dang (ld...@nahannisys.com)
  MFC after:    1 week

Modified:
  head/sys/amd64/vmm/vmm_instruction_emul.c

Modified: head/sys/amd64/vmm/vmm_instruction_emul.c
==============================================================================
--- head/sys/amd64/vmm/vmm_instruction_emul.c   Thu May 21 17:40:53 2015        
(r283254)
+++ head/sys/amd64/vmm/vmm_instruction_emul.c   Thu May 21 18:23:37 2015        
(r283255)
@@ -113,6 +113,10 @@ static const struct vie_op one_byte_opco
                .op_byte = 0x2B,
                .op_type = VIE_OP_TYPE_SUB,
        },
+       [0x39] = {
+               .op_byte = 0x39,
+               .op_type = VIE_OP_TYPE_CMP,
+       },
        [0x3B] = {
                .op_byte = 0x3B,
                .op_type = VIE_OP_TYPE_CMP,
@@ -1050,34 +1054,46 @@ emulate_cmp(void *vm, int vcpuid, uint64
            mem_region_read_t memread, mem_region_write_t memwrite, void *arg)
 {
        int error, size;
-       uint64_t op1, op2, rflags, rflags2;
+       uint64_t regop, memop, op1, op2, rflags, rflags2;
        enum vm_reg_name reg;
 
        size = vie->opsize;
        switch (vie->op.op_byte) {
+       case 0x39:
        case 0x3B:
                /*
+                * 39/r         CMP r/m16, r16
+                * 39/r         CMP r/m32, r32
+                * REX.W 39/r   CMP r/m64, r64
+                *
                 * 3B/r         CMP r16, r/m16
                 * 3B/r         CMP r32, r/m32
                 * REX.W + 3B/r CMP r64, r/m64
                 *
-                * Compare first operand (reg) with second operand (r/m) and
+                * Compare the first operand with the second operand and
                 * set status flags in EFLAGS register. The comparison is
                 * performed by subtracting the second operand from the first
                 * operand and then setting the status flags.
                 */
 
-               /* Get the first operand */
+               /* Get the register operand */
                reg = gpr_map[vie->reg];
-               error = vie_read_register(vm, vcpuid, reg, &op1);
+               error = vie_read_register(vm, vcpuid, reg, &regop);
                if (error)
                        return (error);
 
-               /* Get the second operand */
-               error = memread(vm, vcpuid, gpa, &op2, size, arg);
+               /* Get the memory operand */
+               error = memread(vm, vcpuid, gpa, &memop, size, arg);
                if (error)
                        return (error);
 
+               if (vie->op.op_byte == 0x3B) {
+                       op1 = regop;
+                       op2 = memop;
+               } else {
+                       op1 = memop;
+                       op2 = regop;
+               }
                rflags2 = getcc(size, op1, op2);
                break;
        case 0x80:
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