--- /dev/null
+/*
+ * 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
+
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