From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001
From: root <root@artemis.panaceas.org>
Date: Fri, 25 Dec 2015 04:40:36 +0000
Subject: initial_commit

---
 arch/alpha/lib/copy_user.S | 145 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 145 insertions(+)
 create mode 100644 arch/alpha/lib/copy_user.S

(limited to 'arch/alpha/lib/copy_user.S')

diff --git a/arch/alpha/lib/copy_user.S b/arch/alpha/lib/copy_user.S
new file mode 100644
index 00000000..6f3fab9e
--- /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
-- 
cgit v1.2.3