__strcpy_chk.S revision bdd8f896ddf027491b1e4aa7013a429c8e5702b2 
1/*
2 * Copyright (C) 2013 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 <private/bionic_asm.h>
30
31    .syntax unified
32
33    .thumb
34    .thumb_func
35
36// Get the length of the source string first, then do a memcpy of the data
37// instead of a strcpy.
38ENTRY(__strcpy_chk)
39    pld     [r0, #0]
40    push    {r0, lr}
41    .cfi_adjust_cfa_offset 8
42    .cfi_rel_offset r0, 0
43    .cfi_rel_offset lr, 4
44
45    mov     lr, r2
46    mov     r0, r1
47
48    ands    r3, r1, #7
49    beq     .L_mainloop
50
51    // Align to a double word (64 bits).
52    rsb     r3, r3, #8
53    lsls    ip, r3, #31
54    beq     .L_align_to_32
55
56    ldrb    r2, [r0], #1
57    cbz     r2, .L_update_count_and_finish
58
59.L_align_to_32:
60    bcc     .L_align_to_64
61    ands    ip, r3, #2
62    beq     .L_align_to_64
63
64    ldrb    r2, [r0], #1
65    cbz     r2, .L_update_count_and_finish
66    ldrb    r2, [r0], #1
67    cbz     r2, .L_update_count_and_finish
68
69.L_align_to_64:
70    tst     r3, #4
71    beq     .L_mainloop
72    ldr     r3, [r0], #4
73
74    sub     ip, r3, #0x01010101
75    bic     ip, ip, r3
76    ands    ip, ip, #0x80808080
77    bne     .L_zero_in_second_register
78
79    .p2align 2
80.L_mainloop:
81    ldrd    r2, r3, [r0], #8
82
83    pld     [r0, #64]
84
85    sub     ip, r2, #0x01010101
86    bic     ip, ip, r2
87    ands    ip, ip, #0x80808080
88    bne     .L_zero_in_first_register
89
90    sub     ip, r3, #0x01010101
91    bic     ip, ip, r3
92    ands    ip, ip, #0x80808080
93    bne     .L_zero_in_second_register
94    b       .L_mainloop
95
96.L_update_count_and_finish:
97    sub     r3, r0, r1
98    sub     r3, r3, #1
99    b       .L_check_size
100
101.L_zero_in_first_register:
102    sub     r3, r0, r1
103    lsls    r2, ip, #17
104    bne     .L_sub8_and_finish
105    bcs     .L_sub7_and_finish
106    lsls    ip, ip, #1
107    bne     .L_sub6_and_finish
108
109    sub     r3, r3, #5
110    b       .L_check_size
111
112.L_sub8_and_finish:
113    sub     r3, r3, #8
114    b       .L_check_size
115
116.L_sub7_and_finish:
117    sub     r3, r3, #7
118    b       .L_check_size
119
120.L_sub6_and_finish:
121    sub     r3, r3, #6
122    b       .L_check_size
123
124.L_zero_in_second_register:
125    sub     r3, r0, r1
126    lsls    r2, ip, #17
127    bne     .L_sub4_and_finish
128    bcs     .L_sub3_and_finish
129    lsls    ip, ip, #1
130    bne     .L_sub2_and_finish
131
132    sub     r3, r3, #1
133    b       .L_check_size
134
135.L_sub4_and_finish:
136    sub     r3, r3, #4
137    b       .L_check_size
138
139.L_sub3_and_finish:
140    sub     r3, r3, #3
141    b       .L_check_size
142
143.L_sub2_and_finish:
144    sub     r3, r3, #2
145
146.L_check_size:
147    pld     [r1, #0]
148    pld     [r1, #64]
149    ldr     r0, [sp]
150
151    // Add 1 for copy length to get the string terminator.
152    add     r2, r3, #1
153
154    cmp     r2, lr
155    itt     hi
156    movhi   r0, r2
157    bhi     __strcpy_chk_fail
158
159#include "memcpy_base.S"
160
161END(__strcpy_chk)
162