From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@ppc970.osdl.org>
Date: Sat, 16 Apr 2005 15:20:36 -0700
Subject: Linux-2.6.12-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!
---
 arch/alpha/lib/clear_user.S | 113 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 arch/alpha/lib/clear_user.S

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

diff --git a/arch/alpha/lib/clear_user.S b/arch/alpha/lib/clear_user.S
new file mode 100644
index 00000000000..8860316c195
--- /dev/null
+++ b/arch/alpha/lib/clear_user.S
@@ -0,0 +1,113 @@
+/*
+ * arch/alpha/lib/clear_user.S
+ * Contributed by Richard Henderson <rth@tamu.edu>
+ *
+ * Zero user space, handling exceptions as we go.
+ *
+ * We have to make sure that $0 is always up-to-date and contains the
+ * right "bytes left to zero" 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
+ *	exception pointer in $7
+ *	return address in $28 (exceptions expect it there)
+ *
+ * Outputs:
+ *	bytes left to copy in $0
+ *
+ * Clobbers:
+ *	$1,$2,$3,$4,$5,$6
+ */
+
+/* Allow an exception for an insn; exit if we get one.  */
+#define EX(x,y...)			\
+	99: x,##y;			\
+	.section __ex_table,"a";	\
+	.long 99b - .;			\
+	lda $31, $exception-99b($31); 	\
+	.previous
+
+	.set noat
+	.set noreorder
+	.align 4
+
+	.globl __do_clear_user
+	.ent __do_clear_user
+	.frame	$30, 0, $28
+	.prologue 0
+
+$loop:
+	and	$1, 3, $4	# e0    :
+	beq	$4, 1f		# .. e1 :
+
+0:	EX( stq_u $31, 0($6) )	# e0    : zero one word
+	subq	$0, 8, $0	# .. e1 :
+	subq	$4, 1, $4	# e0    :
+	addq	$6, 8, $6	# .. e1 :
+	bne	$4, 0b		# e1    :
+	unop			#       :
+
+1:	bic	$1, 3, $1	# e0    :
+	beq	$1, $tail	# .. e1 :
+
+2:	EX( stq_u $31, 0($6) )	# e0    : zero four words
+	subq	$0, 8, $0	# .. e1 :
+	EX( stq_u $31, 8($6) )	# e0    :
+	subq	$0, 8, $0	# .. e1 :
+	EX( stq_u $31, 16($6) )	# e0    :
+	subq	$0, 8, $0	# .. e1 :
+	EX( stq_u $31, 24($6) )	# e0    :
+	subq	$0, 8, $0	# .. e1 :
+	subq	$1, 4, $1	# e0    :
+	addq	$6, 32, $6	# .. e1 :
+	bne	$1, 2b		# e1    :
+
+$tail:
+	bne	$2, 1f		# e1    : is there a tail to do?
+	ret	$31, ($28), 1	# .. e1 :
+
+1:	EX( ldq_u $5, 0($6) )	# e0    :
+	clr	$0		# .. e1 :
+	nop			# e1    :
+	mskqh	$5, $0, $5	# e0    :
+	EX( stq_u $5, 0($6) )	# e0    :
+	ret	$31, ($28), 1	# .. e1 :
+
+__do_clear_user:
+	and	$6, 7, $4	# e0    : find dest misalignment
+	beq	$0, $zerolength # .. e1 :
+	addq	$0, $4, $1	# e0    : bias counter
+	and	$1, 7, $2	# e1    : number of bytes in tail
+	srl	$1, 3, $1	# e0    :
+	beq	$4, $loop	# .. e1 :
+
+	EX( ldq_u $5, 0($6) )	# e0    : load dst word to mask back in
+	beq	$1, $oneword	# .. e1 : sub-word store?
+
+	mskql	$5, $6, $5	# e0    : take care of misaligned head
+	addq	$6, 8, $6	# .. e1 :
+	EX( stq_u $5, -8($6) )	# e0    :
+	addq	$0, $4, $0	# .. e1 : bytes left -= 8 - misalignment
+	subq	$1, 1, $1	# e0    :
+	subq	$0, 8, $0	# .. e1 :
+	br	$loop		# e1    :
+	unop			#       :
+
+$oneword:
+	mskql	$5, $6, $4	# e0    :
+	mskqh	$5, $2, $5	# e0    :
+	or	$5, $4, $5	# e1    :
+	EX( stq_u $5, 0($6) )	# e0    :
+	clr	$0		# .. e1 :
+
+$zerolength:
+$exception:
+	ret	$31, ($28), 1	# .. e1 :
+
+	.end __do_clear_user
-- 
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