1 files changed, 145 insertions, 0 deletions

diff --git a/arch/alpha/lib/copy_user.S b/arch/alpha/lib/copy_user.S
new file mode 100644
index 000000000000..6f3fab9eb434
--- /dev/null
+++ b/arch/alpha/lib/copy_user.S
@@ -0,0 +1,145 @@
+/*
+ * arch/alpha/lib/copy_user.S
+ *
+ * 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
+ */
+
+/* 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
+__copy_user:
+        .prologue 0
+        and $6,7,$3
+        beq $0,$35
+        beq $3,$36
+        subq $3,8,$3
+        .align 4
+$37:
+        EXI( ldq_u $1,0($7) )
+        EXO( ldq_u $2,0($6) )
+        extbl $1,$7,$1
+        mskbl $2,$6,$2
+        insbl $1,$6,$1
+        addq $3,1,$3
+        bis $1,$2,$1
+        EXO( stq_u $1,0($6) )
+        subq $0,1,$0
+        addq $6,1,$6
+        addq $7,1,$7
+        beq $0,$41
+        bne $3,$37
+$36:
+        and $7,7,$1
+        bic $0,7,$4
+        beq $1,$43
+        beq $4,$48
+        EXI( ldq_u $3,0($7) )
+        .align 4
+$50:
+        EXI( ldq_u $2,8($7) )
+        subq $4,8,$4
+        extql $3,$7,$3
+        extqh $2,$7,$1
+        bis $3,$1,$1
+        EXO( stq $1,0($6) )
+        addq $7,8,$7
+        subq $0,8,$0
+        addq $6,8,$6
+        bis $2,$2,$3
+        bne $4,$50
+$48:
+        beq $0,$41
+        .align 4
+$57:
+        EXI( ldq_u $1,0($7) )
+        EXO( ldq_u $2,0($6) )
+        extbl $1,$7,$1
+        mskbl $2,$6,$2
+        insbl $1,$6,$1
+        bis $1,$2,$1
+        EXO( stq_u $1,0($6) )
+        subq $0,1,$0
+        addq $6,1,$6
+        addq $7,1,$7
+        bne $0,$57
+        br $31,$41
+        .align 4
+$43:
+        beq $4,$65
+        .align 4
+$66:
+        EXI( ldq $1,0($7) )
+        subq $4,8,$4
+        EXO( stq $1,0($6) )
+        addq $7,8,$7
+        subq $0,8,$0
+        addq $6,8,$6
+        bne $4,$66
+$65:
+        beq $0,$41
+        EXI( ldq $2,0($7) )
+        EXO( ldq $1,0($6) )
+        mskql $2,$0,$2
+        mskqh $1,$0,$1
+        bis $2,$1,$2
+        EXO( stq $2,0($6) )
+        bis $31,$31,$0
+$41:
+$35:
+$exitout:
+        ret $31,($28),1
+
+$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.  */
+
+        mov $0,$1
+$101:
+        EXO ( ldq_u $2,0($6) )
+        subq $1,1,$1
+        mskbl $2,$6,$2
+        EXO ( stq_u $2,0($6) )
+        addq $6,1,$6
+        bgt $1,$101
+        ret $31,($28),1
+
+        .end __copy_user