rewrite copyinstr, copyoutstr, and copystr to avoid use of movs3

which zero fills (using cpynstr semantics). cmps3 has same bug as movs3,
so have to use workaround (but this one is less costly than previously).

SCCS-vsn: sys/tahoe/tahoe/locore.s 1.15

diff --git a/usr/src/sys/tahoe/tahoe/locore.s b/usr/src/sys/tahoe/tahoe/locore.s
index b38da5a..0d5ee42 100644 (file)
--- a/usr/src/sys/tahoe/tahoe/locore.s
+++ b/usr/src/sys/tahoe/tahoe/locore.s
@@ -1,4 +1,4 @@
-/*     locore.s        1.14    87/05/29        */
+/*     locore.s        1.15    87/05/31        */

 
 #include "../tahoe/mtpr.h"
 #include "../tahoe/trap.h"
 
 #include "../tahoe/mtpr.h"
 #include "../tahoe/trap.h"


@@ -965,31 +965,36 @@ ENTRY(ovbcopy, R3|R4)
  *
  * copyinstr(fromaddr, toaddr, maxlength, &lencopied)
  */
  *
  * copyinstr(fromaddr, toaddr, maxlength, &lencopied)
  */

-ENTRY(copyinstr, R3|R4|R5)
+ENTRY(copyinstr, 0)

        movl    12(fp),r5               # r5 = max length
        movl    12(fp),r5               # r5 = max length

-       jlss    8f
+       jlss    5f
+       movl    8(fp),r4                # r4 = kernel address

        movl    4(fp),r0                # r0 = user address
        movl    4(fp),r0                # r0 = user address

-       movl    r0,r3                   # r3 = copy of src for null byte test

        andl3   $(NBPG*CLSIZE-1),r0,r2  # r2 = bytes on first page
        subl3   r2,$(NBPG*CLSIZE),r2
        andl3   $(NBPG*CLSIZE-1),r0,r2  # r2 = bytes on first page
        subl3   r2,$(NBPG*CLSIZE),r2

-       movl    8(fp),r1                # r1 = kernel address

 1:
        cmpl    r5,r2                   # r2 = min(bytes on page, length left);
        jgeq    2f
        movl    r5,r2
 2:
        prober  $1,(r0),r2              # bytes accessible?
 1:
        cmpl    r5,r2                   # r2 = min(bytes on page, length left);
        jgeq    2f
        movl    r5,r2
 2:
        prober  $1,(r0),r2              # bytes accessible?

-       jeql    8f
+       jeql    5f

        subl2   r2,r5                   # update bytes left count
        subl2   r2,r5                   # update bytes left count

-       addl2   r2,r3                   # calculate src+count
-       movs3                           # copy in next piece
-       subl3   r0,r3,r2                # null byte found?
+       movl    r2,r3                   # r3 = saved count
+       movl    r0,r1
+       cmps3                           # check for null
+       tstl    r2

        jneq    3f
        jneq    3f

+       subl2   r3,r0                   # back up r0
+       movl    r4,r1
+       movl    r3,r2
+       movblk                          # copy in next piece
+       movl    r1,r4

        movl    $(NBPG*CLSIZE),r2       # check next page
        tstl    r5                      # run out of space?
        jneq    1b
        movl    $ENOENT,r0              # set error code and return
        movl    $(NBPG*CLSIZE),r2       # check next page
        tstl    r5                      # run out of space?
        jneq    1b
        movl    $ENOENT,r0              # set error code and return

-       jbr     9f
+       jbr     6f

 3:
        tstl    16(fp)                  # return length?
        beql    4f
 3:
        tstl    16(fp)                  # return length?
        beql    4f


@@ -997,15 +1002,20 @@ ENTRY(copyinstr, R3|R4|R5)
        subl2   r2,r5                   #       - unused on this page
        addl3   $1,r5,*16(fp)           #       + the null byte
 4:
        subl2   r2,r5                   #       - unused on this page
        addl3   $1,r5,*16(fp)           #       + the null byte
 4:

+       movl    r4,r1
+       subl3   r2,r3,r2                # calc char cnt
+       subl2   r2,r0                   # back up r0
+       incl    r2                      # add on null byte
+       movblk                          # copy last piece

        clrl    r0
        ret
        clrl    r0
        ret

-8:
+5:

        movl    $EFAULT,r0
        movl    $EFAULT,r0

-9:
+6:

        tstl    16(fp)
        tstl    16(fp)

-       beql    1f
+       beql    7f

        subl3   r5,12(fp),*16(fp)
        subl3   r5,12(fp),*16(fp)

-1:
+7:

        ret
 
 /*
        ret
 
 /*


@@ -1014,48 +1024,51 @@ ENTRY(copyinstr, R3|R4|R5)
  *
  * copyoutstr(fromaddr, toaddr, maxlength, &lencopied)
  */
  *
  * copyoutstr(fromaddr, toaddr, maxlength, &lencopied)
  */

-ENTRY(copyoutstr, R3|R4|R5)
+ENTRY(copyoutstr, 0)

        movl    12(fp),r5               # r5 = max length
        movl    12(fp),r5               # r5 = max length

-       jlss    8b
+       jlss    5b

        movl    4(fp),r0                # r0 = kernel address
        movl    4(fp),r0                # r0 = kernel address

-       movl    r0,r3                   # r3 = copy of src for null byte test
-       movl    8(fp),r1                # r1 = user address
-       andl3   $(NBPG*CLSIZE-1),r1,r2  # r2 = bytes on first page
+       movl    8(fp),r4                # r4 = user address
+       andl3   $(NBPG*CLSIZE-1),r4,r2  # r2 = bytes on first page

        subl3   r2,$(NBPG*CLSIZE),r2
 1:
        cmpl    r5,r2                   # r2 = min(bytes on page, length left);
        jgeq    2f
        movl    r5,r2
 2:
        subl3   r2,$(NBPG*CLSIZE),r2
 1:
        cmpl    r5,r2                   # r2 = min(bytes on page, length left);
        jgeq    2f
        movl    r5,r2
 2:

-       probew  $1,(r1),r2              # bytes accessible?
-       jeql    8b
+       probew  $1,(r4),r2              # bytes accessible?
+       jeql    5b

        subl2   r2,r5                   # update bytes left count
        subl2   r2,r5                   # update bytes left count

-       addl2   r2,r3                   # calculate src+count
-#ifdef notdef
-       movs3                           # copy out next piece
-#else
+       movl    r2,r3                   # r3 = saved count
+       movl    r0,r1
+# This is a workaround for a microcode bug that causes
+# a trap type 9 when cmps3/movs3 touches the last byte
+# on a valid page immediately followed by an invalid page.
+#ifdef good_cmps3
+       cmps3                           # check for null

        tstl    r2
        tstl    r2

-       beql    6f
-4:
-       movb    (r0),(r1)
-       beql    5f
-       incl    r0
-       incl    r1
-       decl    r2
-       bneq    4b
-       jbr     6f
-5:
-       incl    r1
-       decl    r2
-6:
-#endif
-       subl3   r0,r3,r2                # null byte found?

        jneq    3b
        jneq    3b

+#else
+       decl    r2
+       cmps3                           # check for null up to last byte
+       incl    r2
+       cmpl    $1,r2                   # get to last byte on page?
+       bneq    3b
+       tstb    (r0)                    # last byte on page null?
+       beql    9f
+       incl    r0                      # not null, so bump pointer
+9:
+#endif notdef
+       subl2   r3,r0                   # back up r0
+       movl    r4,r1
+       movl    r3,r2
+       movblk                          # copy out next piece
+       movl    r1,r4

        movl    $(NBPG*CLSIZE),r2       # check next page
        tstl    r5                      # run out of space?
        jneq    1b
        movl    $ENOENT,r0              # set error code and return
        movl    $(NBPG*CLSIZE),r2       # check next page
        tstl    r5                      # run out of space?
        jneq    1b
        movl    $ENOENT,r0              # set error code and return

-       jbr     9b
+       jbr     6b

 
 /*
  * Copy a null terminated string from one point to another in
 
 /*
  * Copy a null terminated string from one point to another in


@@ -1063,27 +1076,23 @@ ENTRY(copyoutstr, R3|R4|R5)
  *
  * copystr(fromaddr, toaddr, maxlength, &lencopied)
  */
  *
  * copystr(fromaddr, toaddr, maxlength, &lencopied)
  */

-ENTRY(copystr, R3|R4|R5)
-       movl    12(fp),r5               # r5 = max length
-       jlss    8b
+ENTRY(copystr, 0)
+       movl    12(fp),r3               # r3 = max length
+       jlss    5b

        movl    4(fp),r0                # r0 = src address
        movl    4(fp),r0                # r0 = src address

-       movl    r0,r3                   # r3 = copy of src for null byte test
-       movl    8(fp),r1                # r1 = dest address
-1:
-       movzwl  $65535,r2               # r2 = bytes in first chunk
-       cmpl    r5,r2                   # r2 = min(bytes in chunk, length left);
-       jgeq    2f
-       movl    r5,r2
-2:
-       subl2   r2,r5                   # update bytes left count
-       addl2   r2,r3                   # calculate src+count
-       movs3                           # copy next piece
-       subl3   r0,r3,r2                # null byte found?
+       movl    8(fp),r4                # r4 = dest address
+       clrl    r5                      # r5 = bytes left
+       movl    r3,r2                   # r2 = max bytes to copy
+       movl    r0,r1
+       cmps3                           # check for null
+       tstl    r2

        jneq    3b
        jneq    3b

-       tstl    r5                      # run out of space?
-       jneq    1b
+       subl2   r3,r0                   # back up r0
+       movl    r4,r1
+       movl    r3,r2
+       movblk                          # copy next piece

        movl    $ENOENT,r0              # set error code and return
        movl    $ENOENT,r0              # set error code and return

-       jbr     9b
+       jbr     6b

 
 /*
  * Copy a block of data from the user address space into
 
 /*
  * Copy a block of data from the user address space into