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• Top-level-memory

Rime16

Read a signed 16-bit value from memory via an effective address.

Signature

(rime16 proc-mode eff-addr seg-reg r-x check-alignment? x86) 
  → 
(mv flg value x86-new)

Arguments

check-alignment? — Guard (booleanp check-alignment?).

Returns

value — Type (signed-byte-p 16 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 riml16 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: rime16$inline

(defun rime16$inline (proc-mode eff-addr
                                seg-reg r-x check-alignment? 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))
 (declare (xargs :guard (booleanp check-alignment?)))
 (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 2 x86))
   ((when flg) (mv flg 0 x86))
   ((unless (or (not check-alignment?)
                (address-aligned-p lin-addr 2 nil)))
    (mv (list :unaligned-linear-address lin-addr)
        0 x86)))
  (riml16 lin-addr r-x x86)))

Theorem: return-type-of-rime16.value

(defthm return-type-of-rime16.value
  (implies (x86p x86)
           (b* (((mv ?flg acl2::?value ?x86-new)
                 (rime16$inline proc-mode eff-addr
                                seg-reg r-x check-alignment? x86)))
             (signed-byte-p 16 value)))
  :rule-classes :rewrite)

Theorem: x86p-of-rime16.x86-new

(defthm x86p-of-rime16.x86-new
  (implies (x86p x86)
           (b* (((mv ?flg acl2::?value ?x86-new)
                 (rime16$inline proc-mode eff-addr
                                seg-reg r-x check-alignment? x86)))
             (x86p x86-new)))
  :rule-classes :rewrite)

Theorem: i16p-of-mv-nth-1-rime16

(defthm i16p-of-mv-nth-1-rime16
 (signed-byte-p 16
                (mv-nth 1
                        (rime16 proc-mode eff-addr
                                seg-reg r-x check-alignment? x86)))
 :rule-classes
 (:rewrite
  (:type-prescription
      :corollary
      (integerp (mv-nth 1
                        (rime16 proc-mode eff-addr
                                seg-reg r-x check-alignment? x86)))
      :hints (("Goal" :in-theory '(signed-byte-p integer-range-p))))
  (:linear
    :corollary
    (and (<= -32768
             (mv-nth 1
                     (rime16 proc-mode eff-addr
                             seg-reg r-x check-alignment? x86)))
         (< (mv-nth 1
                    (rime16 proc-mode eff-addr
                            seg-reg r-x check-alignment? x86))
            32768))
    :hints
    (("Goal"
          :in-theory '(signed-byte-p integer-range-p (:e expt)))))))

Theorem: rime16-value-when-error

(defthm rime16-value-when-error
  (implies (mv-nth 0
                   (rime16 proc-mode eff-addr
                           seg-reg r-x check-alignment? x86))
           (equal (mv-nth 1
                          (rime16 proc-mode eff-addr
                                  seg-reg r-x check-alignment? x86))
                  0)))

Theorem: rime16-does-not-affect-state-in-app-view

(defthm rime16-does-not-affect-state-in-app-view
  (implies (app-view x86)
           (equal (mv-nth 2
                          (rime16 proc-mode eff-addr
                                  seg-reg r-x check-alignment? x86))
                  x86)))

Theorem: xr-rime16-state-app-view

(defthm xr-rime16-state-app-view
 (implies
      (app-view x86)
      (equal (xr fld index
                 (mv-nth 2
                         (rime16 proc-mode eff-addr
                                 seg-reg r-x check-alignment? x86)))
             (xr fld index x86))))

Theorem: xr-rime16-state-sys-view

(defthm xr-rime16-state-sys-view
 (implies
      (and (not (equal fld :mem))
           (not (equal fld :fault))
           (not (equal fld :tlb)))
      (equal (xr fld index
                 (mv-nth 2
                         (rime16 proc-mode eff-addr
                                 seg-reg r-x check-alignment? x86)))
             (xr fld index x86))))

Theorem: rime16-xw-app-view

(defthm rime16-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
                      (rime16 proc-mode
                              eff-addr seg-reg r-x check-alignment?
                              (xw fld index value x86)))
              (mv-nth 0
                      (rime16 proc-mode eff-addr
                              seg-reg r-x check-alignment? x86)))
       (equal (mv-nth 1
                      (rime16 proc-mode
                              eff-addr seg-reg r-x check-alignment?
                              (xw fld index value x86)))
              (mv-nth 1
                      (rime16 proc-mode eff-addr
                              seg-reg r-x check-alignment? x86))))))

Theorem: rime16-xw-sys-view

(defthm rime16-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))
       (member-equal fld *x86-field-names-as-keywords*))
  (and
    (equal (mv-nth 0
                   (rime16 proc-mode
                           eff-addr seg-reg r-x check-alignment?
                           (xw fld index value x86)))
           (mv-nth 0
                   (rime16 proc-mode eff-addr
                           seg-reg r-x check-alignment? x86)))
    (equal (mv-nth 1
                   (rime16 proc-mode
                           eff-addr seg-reg r-x check-alignment?
                           (xw fld index value x86)))
           (mv-nth 1
                   (rime16 proc-mode eff-addr
                           seg-reg r-x check-alignment? x86)))
    (equal
         (mv-nth 2
                 (rime16 proc-mode
                         eff-addr seg-reg r-x check-alignment?
                         (xw fld index value x86)))
         (xw fld index value
             (mv-nth 2
                     (rime16 proc-mode eff-addr
                             seg-reg r-x check-alignment? x86)))))))

Theorem: rime16-xw-sys-view-rflags-not-ac

(defthm rime16-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
                   (rime16 proc-mode
                           eff-addr seg-reg r-x check-alignment?
                           (xw :rflags nil value x86)))
           (mv-nth 0
                   (rime16 proc-mode eff-addr
                           seg-reg r-x check-alignment? x86)))
    (equal (mv-nth 1
                   (rime16 proc-mode
                           eff-addr seg-reg r-x check-alignment?
                           (xw :rflags nil value x86)))
           (mv-nth 1
                   (rime16 proc-mode eff-addr
                           seg-reg r-x check-alignment? x86)))
    (equal
         (mv-nth 2
                 (rime16 proc-mode
                         eff-addr seg-reg r-x check-alignment?
                         (xw :rflags nil value x86)))
         (xw :rflags nil value
             (mv-nth 2
                     (rime16 proc-mode eff-addr
                             seg-reg r-x check-alignment? x86)))))))

Theorem: rime16-when-64-bit-modep-and-not-fs/gs

(defthm rime16-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)
                (or (not check-alignment?)
                    (address-aligned-p eff-addr 2 nil)))
           (equal (rime16 0 eff-addr
                          seg-reg r-x check-alignment? x86)
                  (riml16 eff-addr r-x x86))))

Theorem: rime16-unaligned-when-64-bit-modep-and-not-fs/gs

(defthm rime16-unaligned-when-64-bit-modep-and-not-fs/gs
  (implies (and (not (equal seg-reg 4))
                (not (equal seg-reg 5))
                (not (or (not check-alignment?)
                         (address-aligned-p eff-addr 2 nil)))
                (canonical-address-p eff-addr))
           (equal (rime16 0 eff-addr
                          seg-reg r-x check-alignment? x86)
                  (list (list :unaligned-linear-address eff-addr)
                        0 x86))))

Theorem: rime16-when-64-bit-modep-and-fs/gs

(defthm rime16-when-64-bit-modep-and-fs/gs
  (implies
       (or (equal seg-reg 4) (equal seg-reg 5))
       (equal (rime16 0 eff-addr
                      seg-reg r-x check-alignment? 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))
                   ((unless (or (not check-alignment?)
                                (address-aligned-p lin-addr 2 nil)))
                    (mv (list :unaligned-linear-address lin-addr)
                        0 x86)))
                (riml16 lin-addr r-x x86)))))