[PATCH] xtensa: Architecture support for Tensilica Xtensa Part 4

The attached patches provides part 4 of an architecture implementation for the
Tensilica Xtensa CPU series.

Signed-off-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 224 insertions, 0 deletions

diff --git a/arch/xtensa/lib/strncpy_user.S b/arch/xtensa/lib/strncpy_user.S
new file mode 100644
index 000000000000..71d55df43893
--- /dev/null
+++ b/arch/xtensa/lib/strncpy_user.S
@@ -0,0 +1,224 @@
+/*
+ *  arch/xtensa/lib/strncpy_user.S
+ *
+ *  This file is subject to the terms and conditions of the GNU General
+ *  Public License.  See the file "COPYING" in the main directory of
+ *  this archive for more details.
+ *
+ *  Returns: -EFAULT if exception before terminator, N if the entire
+ *  buffer filled, else strlen.
+ *
+ *  Copyright (C) 2002 Tensilica Inc.
+ */
+
+#include <xtensa/coreasm.h>
+#include <linux/errno.h>
+
+/* Load or store instructions that may cause exceptions use the EX macro. */
+
+#define EX(insn,reg1,reg2,offset,handler)	\
+9:	insn	reg1, reg2, offset;		\
+	.section __ex_table, "a";		\
+	.word	9b, handler;			\
+	.previous
+
+/*
+ * char *__strncpy_user(char *dst, const char *src, size_t len)
+ */
+.text
+.begin literal
+.align	4
+.Lmask0:
+	.byte	0xff, 0x00, 0x00, 0x00
+.Lmask1:
+	.byte	0x00, 0xff, 0x00, 0x00
+.Lmask2:
+	.byte	0x00, 0x00, 0xff, 0x00
+.Lmask3:
+	.byte	0x00, 0x00, 0x00, 0xff
+.end literal
+
+# Register use
+#   a0/ return address
+#   a1/ stack pointer
+#   a2/ return value
+#   a3/ src
+#   a4/ len
+#   a5/ mask0
+#   a6/ mask1
+#   a7/ mask2
+#   a8/ mask3
+#   a9/ tmp
+#   a10/ tmp
+#   a11/ dst
+#   a12/ tmp
+
+.align	4
+.global	__strncpy_user
+.type	__strncpy_user,@function
+__strncpy_user:
+	entry	sp, 16		# minimal stack frame
+	# a2/ dst, a3/ src, a4/ len
+	mov	a11, a2		# leave dst in return value register
+	beqz	a4, .Lret	# if len is zero
+	l32r	a5, .Lmask0	# mask for byte 0
+	l32r	a6, .Lmask1	# mask for byte 1
+	l32r	a7, .Lmask2	# mask for byte 2
+	l32r	a8, .Lmask3	# mask for byte 3
+	bbsi.l	a3, 0, .Lsrc1mod2 # if only  8-bit aligned
+	bbsi.l	a3, 1, .Lsrc2mod4 # if only 16-bit aligned
+.Lsrcaligned:	# return here when src is word-aligned
+	srli	a12, a4, 2	# number of loop iterations with 4B per loop
+	movi	a9, 3
+	bnone	a11, a9, .Laligned
+	j	.Ldstunaligned
+
+.Lsrc1mod2:	# src address is odd
+	EX(l8ui, a9, a3, 0, fixup_l)	# get byte 0
+	addi	a3, a3, 1		# advance src pointer
+	EX(s8i, a9, a11, 0, fixup_s)	# store byte 0
+	beqz	a9, .Lret		# if byte 0 is zero
+	addi	a11, a11, 1		# advance dst pointer
+	addi	a4, a4, -1		# decrement len
+	beqz	a4, .Lret		# if len is zero
+	bbci.l	a3, 1, .Lsrcaligned	# if src is now word-aligned
+
+.Lsrc2mod4:	# src address is 2 mod 4
+	EX(l8ui, a9, a3, 0, fixup_l)	# get byte 0
+	/* 1-cycle interlock */
+	EX(s8i, a9, a11, 0, fixup_s)	# store byte 0
+	beqz	a9, .Lret		# if byte 0 is zero
+	addi	a11, a11, 1		# advance dst pointer
+	addi	a4, a4, -1		# decrement len
+	beqz	a4, .Lret		# if len is zero
+	EX(l8ui, a9, a3, 1, fixup_l)	# get byte 0
+	addi	a3, a3, 2		# advance src pointer
+	EX(s8i, a9, a11, 0, fixup_s)	# store byte 0
+	beqz	a9, .Lret		# if byte 0 is zero
+	addi	a11, a11, 1		# advance dst pointer
+	addi	a4, a4, -1		# decrement len
+	bnez	a4, .Lsrcaligned	# if len is nonzero
+.Lret:
+	sub	a2, a11, a2		# compute strlen
+	retw
+
+/*
+ * dst is word-aligned, src is word-aligned
+ */
+	.align	4		# 1 mod 4 alignment for LOOPNEZ
+	.byte	0		# (0 mod 4 alignment for LBEG)
+.Laligned:
+#if XCHAL_HAVE_LOOPS
+	loopnez	a12, .Loop1done
+#else
+	beqz	a12, .Loop1done
+	slli	a12, a12, 2
+	add	a12, a12, a11	# a12 = end of last 4B chunck
+#endif
+.Loop1:
+	EX(l32i, a9, a3, 0, fixup_l)	# get word from src
+	addi	a3, a3, 4		# advance src pointer
+	bnone	a9, a5, .Lz0		# if byte 0 is zero
+	bnone	a9, a6, .Lz1		# if byte 1 is zero
+	bnone	a9, a7, .Lz2		# if byte 2 is zero
+	EX(s32i, a9, a11, 0, fixup_s)	# store word to dst
+	bnone	a9, a8, .Lz3		# if byte 3 is zero
+	addi	a11, a11, 4		# advance dst pointer
+#if !XCHAL_HAVE_LOOPS
+	blt	a11, a12, .Loop1
+#endif
+
+.Loop1done:
+	bbci.l	a4, 1, .L100
+	# copy 2 bytes
+	EX(l16ui, a9, a3, 0, fixup_l)
+	addi	a3, a3, 2		# advance src pointer
+#ifdef __XTENSA_EB__
+	bnone	a9, a7, .Lz0		# if byte 2 is zero
+	bnone	a9, a8, .Lz1		# if byte 3 is zero
+#else
+	bnone	a9, a5, .Lz0		# if byte 0 is zero
+	bnone	a9, a6, .Lz1		# if byte 1 is zero
+#endif
+	EX(s16i, a9, a11, 0, fixup_s)
+	addi	a11, a11, 2		# advance dst pointer
+.L100:
+	bbci.l	a4, 0, .Lret
+	EX(l8ui, a9, a3, 0, fixup_l)
+	/* slot */
+	EX(s8i, a9, a11, 0, fixup_s)
+	beqz	a9, .Lret		# if byte is zero
+	addi	a11, a11, 1-3		# advance dst ptr 1, but also cancel
+					# the effect of adding 3 in .Lz3 code
+	/* fall thru to .Lz3 and "retw" */
+
+.Lz3:	# byte 3 is zero
+	addi	a11, a11, 3		# advance dst pointer
+	sub	a2, a11, a2		# compute strlen
+	retw
+.Lz0:	# byte 0 is zero
+#ifdef __XTENSA_EB__
+	movi	a9, 0
+#endif /* __XTENSA_EB__ */
+	EX(s8i, a9, a11, 0, fixup_s)
+	sub	a2, a11, a2		# compute strlen
+	retw
+.Lz1:	# byte 1 is zero
+#ifdef __XTENSA_EB__
+        extui   a9, a9, 16, 16
+#endif /* __XTENSA_EB__ */
+	EX(s16i, a9, a11, 0, fixup_s)
+	addi	a11, a11, 1		# advance dst pointer
+	sub	a2, a11, a2		# compute strlen
+	retw
+.Lz2:	# byte 2 is zero
+#ifdef __XTENSA_EB__
+        extui   a9, a9, 16, 16
+#endif /* __XTENSA_EB__ */
+	EX(s16i, a9, a11, 0, fixup_s)
+	movi	a9, 0
+	EX(s8i, a9, a11, 2, fixup_s)
+	addi	a11, a11, 2		# advance dst pointer
+	sub	a2, a11, a2		# compute strlen
+	retw
+
+	.align	4		# 1 mod 4 alignment for LOOPNEZ
+	.byte	0		# (0 mod 4 alignment for LBEG)
+.Ldstunaligned:
+/*
+ * for now just use byte copy loop
+ */
+#if XCHAL_HAVE_LOOPS
+	loopnez	a4, .Lunalignedend
+#else
+	beqz	a4, .Lunalignedend
+	add	a12, a11, a4		# a12 = ending address
+#endif /* XCHAL_HAVE_LOOPS */
+.Lnextbyte:
+	EX(l8ui, a9, a3, 0, fixup_l)
+	addi	a3, a3, 1
+	EX(s8i, a9, a11, 0, fixup_s)
+	beqz	a9, .Lunalignedend
+	addi	a11, a11, 1
+#if !XCHAL_HAVE_LOOPS
+	blt	a11, a12, .Lnextbyte
+#endif
+
+.Lunalignedend:
+	sub	a2, a11, a2		# compute strlen
+	retw
+
+
+	.section .fixup, "ax"
+	.align	4
+
+	/* For now, just return -EFAULT.  Future implementations might
+	 * like to clear remaining kernel space, like the fixup
+	 * implementation in memset().  Thus, we differentiate between
+	 * load/store fixups. */
+
+fixup_s:
+fixup_l:
+	movi	a2, -EFAULT
+	retw
+