Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 259 insertions, 0 deletions

diff --git a/arch/alpha/lib/ev6-copy_user.S b/arch/alpha/lib/ev6-copy_user.S
new file mode 100644
index 000000000000..db42ffe9c350
--- /dev/null
+++ b/arch/alpha/lib/ev6-copy_user.S
@@ -0,0 +1,259 @@
+/*
+ * arch/alpha/lib/ev6-copy_user.S
+ *
+ * 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com>
+ *
+ * Copy to/from user space, handling exceptions as we go..  This
+ * isn't exactly pretty.
+ *
+ * This is essentially the same as "memcpy()", but with a few twists.
+ * Notably, we have to make sure that $0 is always up-to-date and
+ * contains the right "bytes left to copy" value (and that it is updated
+ * only _after_ a successful copy). There is also some rather minor
+ * exception setup stuff..
+ *
+ * NOTE! This is not directly C-callable, because the calling semantics are
+ * different:
+ *
+ * Inputs:
+ *      length in $0
+ *      destination address in $6
+ *      source address in $7
+ *      return address in $28
+ *
+ * Outputs:
+ *      bytes left to copy in $0
+ *
+ * Clobbers:
+ *      $1,$2,$3,$4,$5,$6,$7
+ *
+ * Much of the information about 21264 scheduling/coding comes from:
+ *      Compiler Writer's Guide for the Alpha 21264
+ *      abbreviated as 'CWG' in other comments here
+ *      ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
+ * Scheduling notation:
+ *      E       - either cluster
+ *      U       - upper subcluster; U0 - subcluster U0; U1 - subcluster U1
+ *      L       - lower subcluster; L0 - subcluster L0; L1 - subcluster L1
+ */
+
+/* Allow an exception for an insn; exit if we get one.  */
+#define EXI(x,y...)                     \
+        99: x,##y;                      \
+        .section __ex_table,"a";        \
+        .long 99b - .;                  \
+        lda $31, $exitin-99b($31);      \
+        .previous
+
+#define EXO(x,y...)                     \
+        99: x,##y;                      \
+        .section __ex_table,"a";        \
+        .long 99b - .;                  \
+        lda $31, $exitout-99b($31);     \
+        .previous
+
+        .set noat
+        .align 4
+        .globl __copy_user
+        .ent __copy_user
+                                # Pipeline info: Slotting & Comments
+__copy_user:
+        .prologue 0
+        subq $0, 32, $1         # .. E  .. ..   : Is this going to be a small copy?
+        beq $0, $zerolength     # U  .. .. ..   : U L U L
+
+        and $6,7,$3             # .. .. .. E    : is leading dest misalignment
+        ble $1, $onebyteloop    # .. .. U  ..   : 1st branch : small amount of data
+        beq $3, $destaligned    # .. U  .. ..   : 2nd (one cycle fetcher stall)
+        subq $3, 8, $3          # E  .. .. ..   : L U U L : trip counter
+/*
+ * The fetcher stall also hides the 1 cycle cross-cluster stall for $3 (L --> U)
+ * This loop aligns the destination a byte at a time
+ * We know we have at least one trip through this loop
+ */
+$aligndest:
+        EXI( ldbu $1,0($7) )    # .. .. .. L    : Keep loads separate from stores
+        addq $6,1,$6            # .. .. E  ..   : Section 3.8 in the CWG
+        addq $3,1,$3            # .. E  .. ..   :
+        nop                     # E  .. .. ..   : U L U L
+
+/*
+ * the -1 is to compensate for the inc($6) done in a previous quadpack
+ * which allows us zero dependencies within either quadpack in the loop
+ */
+        EXO( stb $1,-1($6) )    # .. .. .. L    :
+        addq $7,1,$7            # .. .. E  ..   : Section 3.8 in the CWG
+        subq $0,1,$0            # .. E  .. ..   :
+        bne $3, $aligndest      # U  .. .. ..   : U L U L
+
+/*
+ * If we fell through into here, we have a minimum of 33 - 7 bytes
+ * If we arrived via branch, we have a minimum of 32 bytes
+ */
+$destaligned:
+        and $7,7,$1             # .. .. .. E    : Check _current_ source alignment
+        bic $0,7,$4             # .. .. E  ..   : number bytes as a quadword loop
+        EXI( ldq_u $3,0($7) )   # .. L  .. ..   : Forward fetch for fallthrough code
+        beq $1,$quadaligned     # U  .. .. ..   : U L U L
+
+/*
+ * In the worst case, we've just executed an ldq_u here from 0($7)
+ * and we'll repeat it once if we take the branch
+ */
+
+/* Misaligned quadword loop - not unrolled.  Leave it that way. */
+$misquad:
+        EXI( ldq_u $2,8($7) )   # .. .. .. L    :
+        subq $4,8,$4            # .. .. E  ..   :
+        extql $3,$7,$3          # .. U  .. ..   :
+        extqh $2,$7,$1          # U  .. .. ..   : U U L L
+
+        bis $3,$1,$1            # .. .. .. E    :
+        EXO( stq $1,0($6) )     # .. .. L  ..   :
+        addq $7,8,$7            # .. E  .. ..   :
+        subq $0,8,$0            # E  .. .. ..   : U L L U
+
+        addq $6,8,$6            # .. .. .. E    :
+        bis $2,$2,$3            # .. .. E  ..   :
+        nop                     # .. E  .. ..   :
+        bne $4,$misquad         # U  .. .. ..   : U L U L
+
+        nop                     # .. .. .. E
+        nop                     # .. .. E  ..
+        nop                     # .. E  .. ..
+        beq $0,$zerolength      # U  .. .. ..   : U L U L
+
+/* We know we have at least one trip through the byte loop */
+        EXI ( ldbu $2,0($7) )   # .. .. .. L    : No loads in the same quad
+        addq $6,1,$6            # .. .. E  ..   : as the store (Section 3.8 in CWG)
+        nop                     # .. E  .. ..   :
+        br $31, $dirtyentry     # L0 .. .. ..   : L U U L
+/* Do the trailing byte loop load, then hop into the store part of the loop */
+
+/*
+ * A minimum of (33 - 7) bytes to do a quad at a time.
+ * Based upon the usage context, it's worth the effort to unroll this loop
+ * $0 - number of bytes to be moved
+ * $4 - number of bytes to move as quadwords
+ * $6 is current destination address
+ * $7 is current source address
+ */
+$quadaligned:
+        subq    $4, 32, $2      # .. .. .. E    : do not unroll for small stuff
+        nop                     # .. .. E  ..
+        nop                     # .. E  .. ..
+        blt     $2, $onequad    # U  .. .. ..   : U L U L
+
+/*
+ * There is a significant assumption here that the source and destination
+ * addresses differ by more than 32 bytes.  In this particular case, a
+ * sparsity of registers further bounds this to be a minimum of 8 bytes.
+ * But if this isn't met, then the output result will be incorrect.
+ * Furthermore, due to a lack of available registers, we really can't
+ * unroll this to be an 8x loop (which would enable us to use the wh64
+ * instruction memory hint instruction).
+ */
+$unroll4:
+        EXI( ldq $1,0($7) )     # .. .. .. L
+        EXI( ldq $2,8($7) )     # .. .. L  ..
+        subq    $4,32,$4        # .. E  .. ..
+        nop                     # E  .. .. ..   : U U L L
+
+        addq    $7,16,$7        # .. .. .. E
+        EXO( stq $1,0($6) )     # .. .. L  ..
+        EXO( stq $2,8($6) )     # .. L  .. ..
+        subq    $0,16,$0        # E  .. .. ..   : U L L U
+
+        addq    $6,16,$6        # .. .. .. E
+        EXI( ldq $1,0($7) )     # .. .. L  ..
+        EXI( ldq $2,8($7) )     # .. L  .. ..
+        subq    $4, 32, $3      # E  .. .. ..   : U U L L : is there enough for another trip?
+
+        EXO( stq $1,0($6) )     # .. .. .. L
+        EXO( stq $2,8($6) )     # .. .. L  ..
+        subq    $0,16,$0        # .. E  .. ..
+        addq    $7,16,$7        # E  .. .. ..   : U L L U
+
+        nop                     # .. .. .. E
+        nop                     # .. .. E  ..
+        addq    $6,16,$6        # .. E  .. ..
+        bgt     $3,$unroll4     # U  .. .. ..   : U L U L
+
+        nop
+        nop
+        nop
+        beq     $4, $noquads
+
+$onequad:
+        EXI( ldq $1,0($7) )
+        subq    $4,8,$4
+        addq    $7,8,$7
+        nop
+
+        EXO( stq $1,0($6) )
+        subq    $0,8,$0
+        addq    $6,8,$6
+        bne     $4,$onequad
+
+$noquads:
+        nop
+        nop
+        nop
+        beq $0,$zerolength
+
+/*
+ * For small copies (or the tail of a larger copy), do a very simple byte loop.
+ * There's no point in doing a lot of complex alignment calculations to try to
+ * to quadword stuff for a small amount of data.
+ *      $0 - remaining number of bytes left to copy
+ *      $6 - current dest addr
+ *      $7 - current source addr
+ */
+
+$onebyteloop:
+        EXI ( ldbu $2,0($7) )   # .. .. .. L    : No loads in the same quad
+        addq $6,1,$6            # .. .. E  ..   : as the store (Section 3.8 in CWG)
+        nop                     # .. E  .. ..   :
+        nop                     # E  .. .. ..   : U L U L
+
+$dirtyentry:
+/*
+ * the -1 is to compensate for the inc($6) done in a previous quadpack
+ * which allows us zero dependencies within either quadpack in the loop
+ */
+        EXO ( stb $2,-1($6) )   # .. .. .. L    :
+        addq $7,1,$7            # .. .. E  ..   : quadpack as the load
+        subq $0,1,$0            # .. E  .. ..   : change count _after_ copy
+        bgt $0,$onebyteloop     # U  .. .. ..   : U L U L
+
+$zerolength:
+$exitout:                       # Destination for exception recovery(?)
+        nop                     # .. .. .. E
+        nop                     # .. .. E  ..
+        nop                     # .. E  .. ..
+        ret $31,($28),1         # L0 .. .. ..   : L U L U
+
+$exitin:
+
+        /* A stupid byte-by-byte zeroing of the rest of the output
+           buffer.  This cures security holes by never leaving 
+           random kernel data around to be copied elsewhere.  */
+
+        nop
+        nop
+        nop
+        mov     $0,$1
+
+$101:
+        EXO ( stb $31,0($6) )   # L
+        subq $1,1,$1            # E
+        addq $6,1,$6            # E
+        bgt $1,$101             # U
+
+        nop
+        nop
+        nop
+        ret $31,($28),1         # L0
+
+        .end __copy_user
+