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 src string, then get the source of the dst string.
37// Check that the two lengths together don't exceed the threshold, then
38// do a memcpy of the data.
39ENTRY(__strcat_chk)
40    pld     [r0, #0]
41    push    {r0, lr}
42    .cfi_def_cfa_offset 8
43    .cfi_rel_offset r0, 0
44    .cfi_rel_offset lr, 4
45    push    {r4, r5}
46    .cfi_adjust_cfa_offset 8
47    .cfi_rel_offset r4, 0
48    .cfi_rel_offset r5, 4
49
50    mov     lr, r2
51
52    // Save the dst register to r5
53    mov     r5, r0
54
55    // Zero out r4
56    eor     r4, r4, r4
57
58    // r1 contains the address of the string to count.
59.L_strlen_start:
60    mov     r0, r1
61    ands    r3, r1, #7
62    beq     .L_mainloop
63
64    // Align to a double word (64 bits).
65    rsb     r3, r3, #8
66    lsls    ip, r3, #31
67    beq     .L_align_to_32
68
69    ldrb    r2, [r1], #1
70    cbz     r2, .L_update_count_and_finish
71
72.L_align_to_32:
73    bcc     .L_align_to_64
74    ands    ip, r3, #2
75    beq     .L_align_to_64
76
77    ldrb    r2, [r1], #1
78    cbz     r2, .L_update_count_and_finish
79    ldrb    r2, [r1], #1
80    cbz     r2, .L_update_count_and_finish
81
82.L_align_to_64:
83    tst     r3, #4
84    beq     .L_mainloop
85    ldr     r3, [r1], #4
86
87    sub     ip, r3, #0x01010101
88    bic     ip, ip, r3
89    ands    ip, ip, #0x80808080
90    bne     .L_zero_in_second_register
91
92    .p2align 2
93.L_mainloop:
94    ldrd    r2, r3, [r1], #8
95
96    pld     [r1, #64]
97
98    sub     ip, r2, #0x01010101
99    bic     ip, ip, r2
100    ands    ip, ip, #0x80808080
101    bne     .L_zero_in_first_register
102
103    sub     ip, r3, #0x01010101
104    bic     ip, ip, r3
105    ands    ip, ip, #0x80808080
106    bne     .L_zero_in_second_register
107    b       .L_mainloop
108
109.L_update_count_and_finish:
110    sub     r3, r1, r0
111    sub     r3, r3, #1
112    b       .L_finish
113
114.L_zero_in_first_register:
115    sub     r3, r1, r0
116    lsls    r2, ip, #17
117    bne     .L_sub8_and_finish
118    bcs     .L_sub7_and_finish
119    lsls    ip, ip, #1
120    bne     .L_sub6_and_finish
121
122    sub     r3, r3, #5
123    b       .L_finish
124
125.L_sub8_and_finish:
126    sub     r3, r3, #8
127    b       .L_finish
128
129.L_sub7_and_finish:
130    sub     r3, r3, #7
131    b       .L_finish
132
133.L_sub6_and_finish:
134    sub     r3, r3, #6
135    b       .L_finish
136
137.L_zero_in_second_register:
138    sub     r3, r1, r0
139    lsls    r2, ip, #17
140    bne     .L_sub4_and_finish
141    bcs     .L_sub3_and_finish
142    lsls    ip, ip, #1
143    bne     .L_sub2_and_finish
144
145    sub     r3, r3, #1
146    b       .L_finish
147
148.L_sub4_and_finish:
149    sub     r3, r3, #4
150    b       .L_finish
151
152.L_sub3_and_finish:
153    sub     r3, r3, #3
154    b       .L_finish
155
156.L_sub2_and_finish:
157    sub     r3, r3, #2
158
159.L_finish:
160    cmp     r4, #0
161    bne     .L_strlen_done
162
163    // Time to get the dst string length.
164    mov     r1, r5
165
166    // Save the original source address to r5.
167    mov     r5, r0
168
169    // Save the current length (adding 1 for the terminator).
170    add     r4, r3, #1
171    b       .L_strlen_start
172
173    // r0 holds the pointer to the dst string.
174    // r3 holds the dst string length.
175    // r4 holds the src string length + 1.
176.L_strlen_done:
177    add     r2, r3, r4
178    cmp     r2, lr
179    itt     hi
180    movhi   r0, lr
181    bhi     __strcat_chk_fail
182
183    // Set up the registers for the memcpy code.
184    mov     r1, r5
185    pld     [r1, #64]
186    mov     r2, r4
187    add     r0, r0, r3
188    pop     {r4, r5}
189    .cfi_adjust_cfa_offset -8
190    .cfi_restore r4
191    .cfi_restore r5
192
193#include "memcpy_base.S"
194
195    // Undo the above cfi directives
196    .cfi_adjust_cfa_offset 8
197    .cfi_rel_offset r4, 0
198    .cfi_rel_offset r5, 4
199END(__strcat_chk)
200