1 files changed, 147 insertions, 0 deletions

diff --git a/arch/xtensa/lib/strnlen_user.S b/arch/xtensa/lib/strnlen_user.S
new file mode 100644
index 000000000000..cdff4d670f3b
--- /dev/null
+++ b/arch/xtensa/lib/strnlen_user.S
@@ -0,0 +1,147 @@
+/*
+ *  arch/xtensa/lib/strnlen_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 strnlen, including trailing zero terminator.
+ *  Zero indicates error.
+ *
+ *  Copyright (C) 2002 Tensilica Inc.
+ */
+
+#include <xtensa/coreasm.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
+
+/*
+ * size_t __strnlen_user(const char *s, 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:
+#   a2/ src
+#   a3/ len
+#   a4/ tmp
+#   a5/ mask0
+#   a6/ mask1
+#   a7/ mask2
+#   a8/ mask3
+#   a9/ tmp
+#   a10/ tmp
+
+.align  4
+.global __strnlen_user
+.type   __strnlen_user,@function
+__strnlen_user:
+        entry   sp, 16          # minimal stack frame
+        # a2/ s, a3/ len
+        addi    a4, a2, -4      # because we overincrement at the end;
+                                # we compensate with load offsets of 4
+        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  a2, 0, .L1mod2  # if only  8-bit aligned
+        bbsi.l  a2, 1, .L2mod4  # if only 16-bit aligned
+
+/*
+ * String is word-aligned.
+ */
+.Laligned:
+        srli    a10, a3, 2      # number of loop iterations with 4B per loop
+#if XCHAL_HAVE_LOOPS
+        loopnez a10, .Ldone
+#else
+        beqz    a10, .Ldone
+        slli    a10, a10, 2
+        add     a10, a10, a4    # a10 = end of last 4B chunk
+#endif /* XCHAL_HAVE_LOOPS */
+.Loop:
+        EX(l32i, a9, a4, 4, lenfixup)   # get next word of string
+        addi    a4, a4, 4               # advance string 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
+        bnone   a9, a8, .Lz3            # if byte 3 is zero
+#if !XCHAL_HAVE_LOOPS
+        blt     a4, a10, .Loop
+#endif
+
+.Ldone:
+        EX(l32i, a9, a4, 4, lenfixup)   # load 4 bytes for remaining checks
+
+        bbci.l  a3, 1, .L100
+        # check two more bytes (bytes 0, 1 of word)
+        addi    a4, a4, 2       # advance string pointer
+        bnone   a9, a5, .Lz0    # if byte 0 is zero
+        bnone   a9, a6, .Lz1    # if byte 1 is zero
+.L100:
+        bbci.l  a3, 0, .L101
+        # check one more byte (byte 2 of word)
+        # Actually, we don't need to check.  Zero or nonzero, we'll add one.
+        # Do not add an extra one for the NULL terminator since we have
+        #  exhausted the original len parameter.
+        addi    a4, a4, 1       # advance string pointer
+.L101:
+        sub     a2, a4, a2      # compute length
+        retw
+
+# NOTE that in several places below, we point to the byte just after
+# the zero byte in order to include the NULL terminator in the count.
+
+.Lz3:   # byte 3 is zero
+        addi    a4, a4, 3       # point to zero byte
+.Lz0:   # byte 0 is zero
+        addi    a4, a4, 1       # point just beyond zero byte
+        sub     a2, a4, a2      # subtract to get length
+        retw
+.Lz1:   # byte 1 is zero
+        addi    a4, a4, 1+1     # point just beyond zero byte
+        sub     a2, a4, a2      # subtract to get length
+        retw
+.Lz2:   # byte 2 is zero
+        addi    a4, a4, 2+1     # point just beyond zero byte
+        sub     a2, a4, a2      # subtract to get length
+        retw
+
+.L1mod2:        # address is odd
+        EX(l8ui, a9, a4, 4, lenfixup)   # get byte 0
+        addi    a4, a4, 1               # advance string pointer
+        beqz    a9, .Lz3                # if byte 0 is zero
+        bbci.l  a4, 1, .Laligned        # if string pointer is now word-aligned
+
+.L2mod4:        # address is 2 mod 4
+        addi    a4, a4, 2       # advance ptr for aligned access
+        EX(l32i, a9, a4, 0, lenfixup)   # get word with first two bytes of string
+        bnone   a9, a7, .Lz2    # if byte 2 (of word, not string) is zero
+        bany    a9, a8, .Laligned # if byte 3 (of word, not string) is nonzero
+        # byte 3 is zero
+        addi    a4, a4, 3+1     # point just beyond zero byte
+        sub     a2, a4, a2      # subtract to get length
+        retw
+
+        .section .fixup, "ax"
+        .align  4
+lenfixup:
+        movi    a2, 0
+        retw
+