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• Top-level-memory

Rme08

Read an unsigned 8-bit value from memory via an effective address.

Signature

(rme08 proc-mode eff-addr seg-reg r-x x86) 
  → 
(mv flg value x86-new)

Returns

value — Type (unsigned-byte-p 8 value), given (x86p x86).

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

The effective address eff-addr is translated to a canonical linear address using ea-to-la. If this translation is successful and no other errors (like alignment errors) occur, then rml08 is called.

Prior to the effective address translation, we check whether read access is allowed. The only case in which it is not allowed is when a read access is attempted on an execute-only code segment, in 32-bit mode. In 64-bit mode, the R bit of the code segment descriptor is ignored (see Atmel manual, Dec'17, Volume 2, Section 4.8.1).

Definitions and Theorems

Function: rme08$inline

(defun rme08$inline (proc-mode eff-addr seg-reg r-x x86)
 (declare (xargs :stobjs (x86)))
 (declare (type (integer 0 4) proc-mode)
          (type (signed-byte 64) eff-addr)
          (type (integer 0 5) seg-reg)
          (type (member :r :x) r-x))
 (b*
  (((when
     (and (/= proc-mode 0)
          (= seg-reg 1)
          (eq r-x :r)
          (b* ((attr (loghead 16 (seg-hidden-attri seg-reg x86)))
               (r (code-segment-descriptor-attributesbits->r attr)))
            (= r 0))))
    (mv (list :execute-only-code-segment eff-addr)
        0 x86))
   ((mv flg lin-addr)
    (ea-to-la proc-mode eff-addr seg-reg 1 x86))
   ((when flg) (mv flg 0 x86)))
  (rml08 lin-addr r-x x86)))

Theorem: return-type-of-rme08.value

(defthm return-type-of-rme08.value
  (implies (x86p x86)
           (b* (((mv ?flg acl2::?value ?x86-new)
                 (rme08$inline proc-mode eff-addr seg-reg r-x x86)))
             (unsigned-byte-p 8 value)))
  :rule-classes :rewrite)

Theorem: x86p-of-rme08.x86-new

(defthm x86p-of-rme08.x86-new
  (implies (x86p x86)
           (b* (((mv ?flg acl2::?value ?x86-new)
                 (rme08$inline proc-mode eff-addr seg-reg r-x x86)))
             (x86p x86-new)))
  :rule-classes :rewrite)

Theorem: n08p-of-mv-nth-1-rme08

(defthm n08p-of-mv-nth-1-rme08
 (unsigned-byte-p
      8
      (mv-nth 1
              (rme08 proc-mode eff-addr seg-reg r-x x86)))
 :rule-classes
 (:rewrite
  (:type-prescription
      :corollary
      (natp (mv-nth 1
                    (rme08 proc-mode eff-addr seg-reg r-x x86)))
      :hints
      (("Goal" :in-theory '(unsigned-byte-p integer-range-p natp))))
  (:linear
   :corollary
   (and (<= 0
            (mv-nth 1
                    (rme08 proc-mode eff-addr seg-reg r-x x86)))
        (< (mv-nth 1
                   (rme08 proc-mode eff-addr seg-reg r-x x86))
           256))
   :hints
   (("Goal"
        :in-theory '(unsigned-byte-p integer-range-p (:e expt)))))))

Theorem: rme08-value-when-error

(defthm rme08-value-when-error
 (implies (mv-nth 0
                  (rme08 proc-mode eff-addr seg-reg r-x x86))
          (equal (mv-nth 1
                         (rme08 proc-mode eff-addr seg-reg r-x x86))
                 0)))

Theorem: rme08-does-not-affect-state-in-app-view

(defthm rme08-does-not-affect-state-in-app-view
 (implies (app-view x86)
          (equal (mv-nth 2
                         (rme08 proc-mode eff-addr seg-reg r-x x86))
                 x86)))

Theorem: xr-rme08-state-app-view

(defthm xr-rme08-state-app-view
 (implies
     (app-view x86)
     (equal (xr fld index
                (mv-nth 2
                        (rme08 proc-mode eff-addr seg-reg r-x x86)))
            (xr fld index x86))))

Theorem: xr-rme08-state-sys-view

(defthm xr-rme08-state-sys-view
 (implies
     (and (not (equal fld :mem))
          (not (equal fld :fault))
          (not (equal fld :tlb)))
     (equal (xr fld index
                (mv-nth 2
                        (rme08 proc-mode eff-addr seg-reg r-x x86)))
            (xr fld index x86))))

Theorem: rme08-xw-app-view

(defthm rme08-xw-app-view
 (implies
  (and (app-view x86)
       (not (equal fld :mem))
       (not (equal fld :app-view))
       (not (equal fld :seg-hidden-base))
       (not (equal fld :seg-hidden-limit))
       (not (equal fld :seg-hidden-attr))
       (not (equal fld :seg-visible))
       (not (equal fld :msr)))
  (and
      (equal (mv-nth 0
                     (rme08 proc-mode eff-addr
                            seg-reg r-x (xw fld index value x86)))
             (mv-nth 0
                     (rme08 proc-mode eff-addr seg-reg r-x x86)))
      (equal (mv-nth 1
                     (rme08 proc-mode eff-addr
                            seg-reg r-x (xw fld index value x86)))
             (mv-nth 1
                     (rme08 proc-mode eff-addr seg-reg r-x x86))))))

Theorem: rme08-xw-sys-view

(defthm rme08-xw-sys-view
 (implies
   (and (not (app-view x86))
        (not (equal fld :fault))
        (not (equal fld :seg-visible))
        (not (equal fld :seg-hidden-base))
        (not (equal fld :seg-hidden-limit))
        (not (equal fld :seg-hidden-attr))
        (not (equal fld :mem))
        (not (equal fld :ctr))
        (not (equal fld :msr))
        (not (equal fld :rflags))
        (not (equal fld :app-view))
        (not (equal fld :tlb))
        (not (equal fld :marking-view))
        (not (equal fld :implicit-supervisor-access)))
   (and (equal (mv-nth 0
                       (rme08 proc-mode eff-addr
                              seg-reg r-x (xw fld index value x86)))
               (mv-nth 0
                       (rme08 proc-mode eff-addr seg-reg r-x x86)))
        (equal (mv-nth 1
                       (rme08 proc-mode eff-addr
                              seg-reg r-x (xw fld index value x86)))
               (mv-nth 1
                       (rme08 proc-mode eff-addr seg-reg r-x x86)))
        (equal (mv-nth 2
                       (rme08 proc-mode eff-addr
                              seg-reg r-x (xw fld index value x86)))
               (xw fld index value
                   (mv-nth 2
                           (rme08 proc-mode
                                  eff-addr seg-reg r-x x86)))))))

Theorem: rme08-xw-sys-view-rflags-not-ac

(defthm rme08-xw-sys-view-rflags-not-ac
 (implies
  (and (not (app-view x86))
       (equal (rflagsbits->ac value)
              (rflagsbits->ac (rflags x86))))
  (and
      (equal (mv-nth 0
                     (rme08 proc-mode eff-addr
                            seg-reg r-x (xw :rflags nil value x86)))
             (mv-nth 0
                     (rme08 proc-mode eff-addr seg-reg r-x x86)))
      (equal (mv-nth 1
                     (rme08 proc-mode eff-addr
                            seg-reg r-x (xw :rflags nil value x86)))
             (mv-nth 1
                     (rme08 proc-mode eff-addr seg-reg r-x x86)))
      (equal (mv-nth 2
                     (rme08 proc-mode eff-addr
                            seg-reg r-x (xw :rflags nil value x86)))
             (xw :rflags nil value
                 (mv-nth 2
                         (rme08 proc-mode
                                eff-addr seg-reg r-x x86)))))))

Theorem: rme08-when-64-bit-modep-and-not-fs/gs

(defthm rme08-when-64-bit-modep-and-not-fs/gs
  (implies (and (not (equal seg-reg 4))
                (not (equal seg-reg 5))
                (canonical-address-p eff-addr))
           (equal (rme08 0 eff-addr seg-reg r-x x86)
                  (rml08 eff-addr r-x x86))))

Theorem: rme08-when-64-bit-modep-and-fs/gs

(defthm rme08-when-64-bit-modep-and-fs/gs
  (implies
       (or (equal seg-reg 4) (equal seg-reg 5))
       (equal (rme08 0 eff-addr seg-reg r-x x86)
              (b* (((mv flg lin-addr)
                    (b* (((mv base & &)
                          (segment-base-and-bounds 0 seg-reg x86))
                         (lin-addr (i64 (+ base (n64 eff-addr)))))
                      (if (canonical-address-p lin-addr)
                          (mv nil lin-addr)
                        (mv (list :non-canonical-address lin-addr)
                            0))))
                   ((when flg) (mv flg 0 x86)))
                (rml08 lin-addr r-x x86)))))