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• X86-decoder

Vex-decode-and-execute

Signature

(vex-decode-and-execute proc-mode start-rip temp-rip 
                        prefixes rex-byte vex-prefixes x86) 
 
  → 
x86

Arguments

temp-rip — temp-rip points to the byte following the first two VEX prefixes that were already read and placed in the vex-prefixes structure in x86-fetch-decode-execute.

vex-prefixes — Only byte0 and byte1 fields are populated when this function is called.

Returns

x86 — Type (x86p x86), given (x86p x86).

vex-decode-and-execute dispatches control to VEX-encoded instructions.

Reference: Intel Vol. 2A, Section 2.3: Intel Advanced Vector Extensions (Intel AVX)

Definitions and Theorems

Function: vex-decode-and-execute

(defun vex-decode-and-execute
       (proc-mode start-rip temp-rip
                  prefixes rex-byte vex-prefixes x86)
 (declare (xargs :stobjs (x86)))
 (declare (type (integer 0 4) proc-mode)
          (type (signed-byte 48) start-rip)
          (type (signed-byte 48) temp-rip)
          (type (unsigned-byte 52) prefixes)
          (type (unsigned-byte 8) rex-byte)
          (type (unsigned-byte 24) vex-prefixes))
 (declare (xargs :guard (and (prefixes-p prefixes)
                             (vex-prefixes-byte0-p vex-prefixes))))
 (let ((__function__ 'vex-decode-and-execute))
  (declare (ignorable __function__))
  (b*
   ((ctx 'vex-decode-and-execute)
    ((when (not (equal rex-byte 0)))
     (!!fault-fresh :ud
                    :vex-prefixes vex-prefixes
                    :rex rex-byte))
    ((when (equal (the (unsigned-byte 8)
                       (prefixes->lck prefixes))
                  240))
     (!!fault-fresh :ud :vex-prefixes
                    vex-prefixes :lock-prefix))
    ((when (equal (the (unsigned-byte 8)
                       (prefixes->rep prefixes))
                  242))
     (!!fault-fresh :ud
                    :vex-prefixes vex-prefixes :f2-prefix))
    ((when (equal (the (unsigned-byte 8)
                       (prefixes->rep prefixes))
                  243))
     (!!fault-fresh :ud
                    :vex-prefixes vex-prefixes :f3-prefix))
    ((when (equal (the (unsigned-byte 8)
                       (prefixes->opr prefixes))
                  102))
     (!!fault-fresh :ud
                    :vex-prefixes vex-prefixes :66-prefix))
    (vex2-prefix? (equal (vex-prefixes->byte0 vex-prefixes)
                         197))
    (vex3-prefix? (equal (vex-prefixes->byte0 vex-prefixes)
                         196))
    (vex-byte1 (vex-prefixes->byte1 vex-prefixes))
    ((mv vex3-0f-map?
         vex3-0f38-map? vex3-0f3a-map?)
     (if vex3-prefix? (mv (equal (vex3-byte1->m-mmmm vex-byte1) 1)
                          (equal (vex3-byte1->m-mmmm vex-byte1) 2)
                          (equal (vex3-byte1->m-mmmm vex-byte1)
                                 3))
       (mv nil nil nil)))
    ((when (and vex3-prefix?
                (not (or vex3-0f-map?
                         vex3-0f38-map? vex3-0f3a-map?))))
     (!!fault-fresh :ud
                    :vex-prefixes vex-prefixes
                    :m-mmmm vex-byte1))
    ((mv flg0
         (the (unsigned-byte 8) byte2/next-byte)
         x86)
     (rme08 proc-mode temp-rip 1 :x x86))
    ((when flg0)
     (!!ms-fresh :vex-byte2/next-byte-read-error flg0))
    ((mv flg1 temp-rip)
     (add-to-*ip proc-mode temp-rip 1 x86))
    ((when flg1)
     (!!ms-fresh :increment-error flg1))
    (vex-prefixes
         (if vex3-prefix?
             (!vex-prefixes->byte2 byte2/next-byte vex-prefixes)
           vex-prefixes))
    ((mv flg2 (the (unsigned-byte 8) next-byte)
         x86)
     (if vex3-prefix? (rme08 proc-mode temp-rip 1 :x x86)
       (mv nil 0 x86)))
    ((when flg2)
     (!!ms-fresh :next-byte-read-error flg2))
    ((mv flg3 temp-rip)
     (if vex3-prefix? (add-to-*ip proc-mode temp-rip 1 x86)
       (mv nil temp-rip)))
    ((when flg3)
     (!!ms-fresh :increment-error flg3))
    (opcode (the (unsigned-byte 8)
                 (if vex3-prefix? next-byte
                   byte2/next-byte)))
    (modr/m? (vex-opcode-modr/m-p vex-prefixes opcode))
    ((mv flg4 (the (unsigned-byte 8) modr/m)
         x86)
     (if modr/m? (rme08 proc-mode temp-rip 1 :x x86)
       (mv nil 0 x86)))
    ((when flg4)
     (!!ms-fresh :modr/m-byte-read-error flg4))
    ((mv flg5 temp-rip)
     (if modr/m? (add-to-*ip proc-mode temp-rip 1 x86)
       (mv nil temp-rip)))
    ((when flg5)
     (!!ms-fresh :increment-error flg5))
    (sib?
      (and modr/m?
           (b* ((p4? (eql 103
                          (the (unsigned-byte 8)
                               (prefixes->adr prefixes))))
                (16-bit-addressp
                     (eql 2
                          (select-address-size proc-mode p4? x86))))
             (x86-decode-sib-p modr/m 16-bit-addressp))))
    ((mv flg6 (the (unsigned-byte 8) sib)
         x86)
     (if sib? (rme08 proc-mode temp-rip 1 :x x86)
       (mv nil 0 x86)))
    ((when flg6)
     (!!ms-fresh :sib-byte-read-error flg6))
    ((mv flg7 temp-rip)
     (if sib? (add-to-*ip proc-mode temp-rip 1 x86)
       (mv nil temp-rip)))
    ((when flg7)
     (!!ms-fresh :increment-error flg7)))
   (cond ((mbe :logic (vex-prefixes-map-p 15 vex-prefixes)
               :exec (or vex2-prefix?
                         (and vex3-prefix? vex3-0f-map?)))
          (vex-0f-execute proc-mode
                          start-rip temp-rip prefixes rex-byte
                          vex-prefixes opcode modr/m sib x86))
         ((mbe :logic (vex-prefixes-map-p 3896 vex-prefixes)
               :exec (and vex3-prefix? vex3-0f38-map?))
          (vex-0f38-execute proc-mode
                            start-rip temp-rip prefixes rex-byte
                            vex-prefixes opcode modr/m sib x86))
         ((mbe :logic (vex-prefixes-map-p 3898 vex-prefixes)
               :exec (and vex3-prefix? vex3-0f3a-map?))
          (vex-0f3a-execute proc-mode
                            start-rip temp-rip prefixes rex-byte
                            vex-prefixes opcode modr/m sib x86))
         (t (!!ms-fresh :illegal-value-of-vex-m-mmmm))))))

Theorem: x86p-of-vex-decode-and-execute

(defthm x86p-of-vex-decode-and-execute
 (implies
  (x86p x86)
  (b*
   ((x86
       (vex-decode-and-execute proc-mode start-rip temp-rip
                               prefixes rex-byte vex-prefixes x86)))
   (x86p x86)))
 :rule-classes :rewrite)