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
+