memset.S revision 851e68a2402fa414544e66650e09dfdaac813e51 
1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *  * Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *  * Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *    the documentation and/or other materials provided with the
13 *    distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <machine/cpu-features.h>
30#include <private/bionic_asm.h>
31#include <private/libc_events.h>
32
33/*
34 * This code assumes it is running on a processor that supports all arm v7
35 * instructions, that supports neon instructions, and that supports
36 * unaligned neon instruction accesses to memory.
37 */
38
39    .fpu    neon
40
41ENTRY(__memset_chk)
42        cmp         r2, r3
43        bls         .L_done
44
45        // Preserve lr for backtrace.
46        .save       {lr}
47        push        {lr}
48        .cfi_def_cfa_offset 4
49        .cfi_rel_offset lr, 0
50
51        ldr         r0, error_message
52        ldr         r1, error_code
531:
54        add         r0, pc
55        bl          __fortify_chk_fail
56error_code:
57        .word       BIONIC_EVENT_MEMSET_BUFFER_OVERFLOW
58error_message:
59        .word       error_string-(1b+8)
60END(__memset_chk)
61
62ENTRY(bzero)
63        mov     r2, r1
64        mov     r1, #0
65
66.L_done:
67        // Fall through to memset...
68END(bzero)
69
70/* memset() returns its first argument.  */
71ENTRY(memset)
72        .save       {r0}
73        stmfd       sp!, {r0}
74        .cfi_def_cfa_offset 4
75        .cfi_rel_offset r0, 0
76
77        vdup.8      q0, r1
78
79        /* make sure we have at least 32 bytes to write */
80        subs        r2, r2, #32
81        blo         2f
82        vmov        q1, q0
83
841:      /* The main loop writes 32 bytes at a time */
85        subs        r2, r2, #32
86        vst1.8      {d0 - d3}, [r0]!
87        bhs         1b
88
892:      /* less than 32 left */
90        add         r2, r2, #32
91        tst         r2, #0x10
92        beq         3f
93
94        // writes 16 bytes, 128-bits aligned
95        vst1.8      {d0, d1}, [r0]!
963:      /* write up to 15-bytes (count in r2) */
97        movs        ip, r2, lsl #29
98        bcc         1f
99        vst1.8      {d0}, [r0]!
1001:      bge         2f
101        vst1.32     {d0[0]}, [r0]!
1022:      movs        ip, r2, lsl #31
103        strmib      r1, [r0], #1
104        strcsb      r1, [r0], #1
105        strcsb      r1, [r0], #1
106        ldmfd       sp!, {r0}
107        bx          lr
108END(memset)
109
110        .data
111error_string:
112        .string     "memset: prevented write past end of buffer"
113