summaryrefslogtreecommitdiffstats
path: root/arch/xtensa/lib/strncpy_user.S
diff options
context:
space:
mode:
Diffstat (limited to 'arch/xtensa/lib/strncpy_user.S')
-rw-r--r--arch/xtensa/lib/strncpy_user.S217
1 files changed, 217 insertions, 0 deletions
diff --git a/arch/xtensa/lib/strncpy_user.S b/arch/xtensa/lib/strncpy_user.S
new file mode 100644
index 0000000000..9841d1694c
--- /dev/null
+++ b/arch/xtensa/lib/strncpy_user.S
@@ -0,0 +1,217 @@
+/*
+ * 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 <linux/errno.h>
+#include <linux/linkage.h>
+#include <asm/asmmacro.h>
+#include <asm/core.h>
+
+/*
+ * char *__strncpy_user(char *dst, const char *src, size_t len)
+ */
+
+#ifdef __XTENSA_EB__
+# define MASK0 0xff000000
+# define MASK1 0x00ff0000
+# define MASK2 0x0000ff00
+# define MASK3 0x000000ff
+#else
+# define MASK0 0x000000ff
+# define MASK1 0x0000ff00
+# define MASK2 0x00ff0000
+# define MASK3 0xff000000
+#endif
+
+# 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
+
+.text
+ENTRY(__strncpy_user)
+
+ abi_entry_default
+ # a2/ dst, a3/ src, a4/ len
+ mov a11, a2 # leave dst in return value register
+ beqz a4, .Lret # if len is zero
+ movi a5, MASK0 # mask for byte 0
+ movi a6, MASK1 # mask for byte 1
+ movi a7, MASK2 # mask for byte 2
+ movi a8, MASK3 # 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 a10, 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(11f) l8ui a9, a3, 0 # get byte 0
+ addi a3, a3, 1 # advance src pointer
+EX(10f) s8i a9, a11, 0 # 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(11f) l8ui a9, a3, 0 # get byte 0
+ /* 1-cycle interlock */
+EX(10f) s8i a9, a11, 0 # 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(11f) l8ui a9, a3, 1 # get byte 0
+ addi a3, a3, 2 # advance src pointer
+EX(10f) s8i a9, a11, 0 # 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
+ abi_ret_default
+
+/*
+ * 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 a10, .Loop1done
+#else
+ beqz a10, .Loop1done
+ slli a10, a10, 2
+ add a10, a10, a11 # a10 = end of last 4B chunck
+#endif
+.Loop1:
+EX(11f) l32i a9, a3, 0 # 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(10f) s32i a9, a11, 0 # 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, a10, .Loop1
+#endif
+
+.Loop1done:
+ bbci.l a4, 1, .L100
+ # copy 2 bytes
+EX(11f) l16ui a9, a3, 0
+ 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(10f) s16i a9, a11, 0
+ addi a11, a11, 2 # advance dst pointer
+.L100:
+ bbci.l a4, 0, .Lret
+EX(11f) l8ui a9, a3, 0
+ /* slot */
+EX(10f) s8i a9, a11, 0
+ 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
+ abi_ret_default
+.Lz0: # byte 0 is zero
+#ifdef __XTENSA_EB__
+ movi a9, 0
+#endif /* __XTENSA_EB__ */
+EX(10f) s8i a9, a11, 0
+ sub a2, a11, a2 # compute strlen
+ abi_ret_default
+.Lz1: # byte 1 is zero
+#ifdef __XTENSA_EB__
+ extui a9, a9, 16, 16
+#endif /* __XTENSA_EB__ */
+EX(10f) s16i a9, a11, 0
+ addi a11, a11, 1 # advance dst pointer
+ sub a2, a11, a2 # compute strlen
+ abi_ret_default
+.Lz2: # byte 2 is zero
+#ifdef __XTENSA_EB__
+ extui a9, a9, 16, 16
+#endif /* __XTENSA_EB__ */
+EX(10f) s16i a9, a11, 0
+ movi a9, 0
+EX(10f) s8i a9, a11, 2
+ addi a11, a11, 2 # advance dst pointer
+ sub a2, a11, a2 # compute strlen
+ abi_ret_default
+
+ .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 a10, a11, a4 # a10 = ending address
+#endif /* XCHAL_HAVE_LOOPS */
+.Lnextbyte:
+EX(11f) l8ui a9, a3, 0
+ addi a3, a3, 1
+EX(10f) s8i a9, a11, 0
+ beqz a9, .Lunalignedend
+ addi a11, a11, 1
+#if !XCHAL_HAVE_LOOPS
+ blt a11, a10, .Lnextbyte
+#endif
+
+.Lunalignedend:
+ sub a2, a11, a2 # compute strlen
+ abi_ret_default
+
+ENDPROC(__strncpy_user)
+EXPORT_SYMBOL(__strncpy_user)
+
+ .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. */
+
+10:
+11:
+ movi a2, -EFAULT
+ abi_ret_default