1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
|
From 1da064c015dce624cb19fcdc0bace7af2bd8caec Mon Sep 17 00:00:00 2001
From: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Thu, 30 Dec 2021 17:08:36 +0000
Subject: [PATCH 4/4] aarch64: Move ld.so _start to separate file and drop
_dl_skip_args
Conflict:NA
Reference:https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=1da064c015dce624cb19fcdc0bace7af2bd8caec
A separate asm file is easier to maintain than a macro that expands to
inline asm.
The RTLD_START macro is only needed now because _dl_start is local in
rtld.c, but _start has to call it, if _dl_start was made hidden then it
could be empty.
_dl_skip_args is no longer needed.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
---
sysdeps/aarch64/Makefile | 1 +
sysdeps/aarch64/dl-machine.h | 77 +-----------------------------------
sysdeps/aarch64/dl-start.S | 53 +++++++++++++++++++++++++
3 files changed, 56 insertions(+), 75 deletions(-)
create mode 100644 sysdeps/aarch64/dl-start.S
diff --git a/sysdeps/aarch64/Makefile b/sysdeps/aarch64/Makefile
index 7183895d04..17fb1c5b72 100644
--- a/sysdeps/aarch64/Makefile
+++ b/sysdeps/aarch64/Makefile
@@ -33,6 +33,7 @@ tst-audit27-ENV = LD_AUDIT=$(objpfx)tst-auditmod27.so
endif
ifeq ($(subdir),elf)
+sysdep-rtld-routines += dl-start
sysdep-dl-routines += tlsdesc dl-tlsdesc
gen-as-const-headers += dl-link.sym
diff --git a/sysdeps/aarch64/dl-machine.h b/sysdeps/aarch64/dl-machine.h
index b40050a981..fe120bb507 100644
--- a/sysdeps/aarch64/dl-machine.h
+++ b/sysdeps/aarch64/dl-machine.h
@@ -105,81 +105,8 @@ elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
return lazy;
}
-/* Initial entry point for the dynamic linker. The C function
- _dl_start is the real entry point, its return value is the user
- program's entry point */
-#ifdef __LP64__
-# define RTLD_START RTLD_START_1 ("x", "3", "sp")
-#else
-# define RTLD_START RTLD_START_1 ("w", "2", "wsp")
-#endif
-
-
-#define RTLD_START_1(PTR, PTR_SIZE_LOG, PTR_SP) asm ("\
-.text \n\
-.globl _start \n\
-.type _start, %function \n\
-.globl _dl_start_user \n\
-.type _dl_start_user, %function \n\
-_start: \n\
- // bti c \n\
- hint 34 \n\
- mov " PTR "0, " PTR_SP " \n\
- bl _dl_start \n\
- // returns user entry point in x0 \n\
- mov x21, x0 \n\
-_dl_start_user: \n\
- // get the original arg count \n\
- ldr " PTR "1, [sp] \n\
- // get the argv address \n\
- add " PTR "2, " PTR_SP ", #(1<<" PTR_SIZE_LOG ") \n\
- // get _dl_skip_args to see if we were \n\
- // invoked as an executable \n\
- adrp x4, _dl_skip_args \n\
- ldr w4, [x4, #:lo12:_dl_skip_args] \n\
- // do we need to adjust argc/argv \n\
- cmp w4, 0 \n\
- beq .L_done_stack_adjust \n\
- // subtract _dl_skip_args from original arg count \n\
- sub " PTR "1, " PTR "1, " PTR "4 \n\
- // store adjusted argc back to stack \n\
- str " PTR "1, [sp] \n\
- // find the first unskipped argument \n\
- mov " PTR "3, " PTR "2 \n\
- add " PTR "4, " PTR "2, " PTR "4, lsl #" PTR_SIZE_LOG " \n\
- // shuffle argv down \n\
-1: ldr " PTR "5, [x4], #(1<<" PTR_SIZE_LOG ") \n\
- str " PTR "5, [x3], #(1<<" PTR_SIZE_LOG ") \n\
- cmp " PTR "5, #0 \n\
- bne 1b \n\
- // shuffle envp down \n\
-1: ldr " PTR "5, [x4], #(1<<" PTR_SIZE_LOG ") \n\
- str " PTR "5, [x3], #(1<<" PTR_SIZE_LOG ") \n\
- cmp " PTR "5, #0 \n\
- bne 1b \n\
- // shuffle auxv down \n\
-1: ldp " PTR "0, " PTR "5, [x4, #(2<<" PTR_SIZE_LOG ")]! \n\
- stp " PTR "0, " PTR "5, [x3], #(2<<" PTR_SIZE_LOG ") \n\
- cmp " PTR "0, #0 \n\
- bne 1b \n\
- // Update _dl_argv \n\
- adrp x3, __GI__dl_argv \n\
- str " PTR "2, [x3, #:lo12:__GI__dl_argv] \n\
-.L_done_stack_adjust: \n\
- // compute envp \n\
- add " PTR "3, " PTR "2, " PTR "1, lsl #" PTR_SIZE_LOG " \n\
- add " PTR "3, " PTR "3, #(1<<" PTR_SIZE_LOG ") \n\
- adrp x16, _rtld_local \n\
- add " PTR "16, " PTR "16, #:lo12:_rtld_local \n\
- ldr " PTR "0, [x16] \n\
- bl _dl_init \n\
- // load the finalizer function \n\
- adrp x0, _dl_fini \n\
- add " PTR "0, " PTR "0, #:lo12:_dl_fini \n\
- // jump to the user_s entry point \n\
- mov x16, x21 \n\
- br x16 \n\
-");
+/* In elf/rtld.c _dl_start should be global so dl-start.S can reference it. */
+#define RTLD_START asm (".globl _dl_start");
#define elf_machine_type_class(type) \
((((type) == AARCH64_R(JUMP_SLOT) \
diff --git a/sysdeps/aarch64/dl-start.S b/sysdeps/aarch64/dl-start.S
new file mode 100644
index 0000000000..a3a57bd5a1
--- /dev/null
+++ b/sysdeps/aarch64/dl-start.S
@@ -0,0 +1,53 @@
+/* ld.so _start code.
+ Copyright (C) 2022 Free Software Foundation, Inc.
+
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+
+ENTRY (_start)
+ /* Create an initial frame with 0 LR and FP */
+ cfi_undefined (x30)
+ mov x29, #0
+ mov x30, #0
+
+ mov x0, sp
+ PTR_ARG (0)
+ bl _dl_start
+ /* Returns user entry point in x0. */
+ mov PTR_REG (21), PTR_REG (0)
+.globl _dl_start_user
+.type _dl_start_user, %function
+_dl_start_user:
+ /* Get argc. */
+ ldr PTR_REG (1), [sp]
+ /* Get argv. */
+ add x2, sp, PTR_SIZE
+ /* Compute envp. */
+ add PTR_REG (3), PTR_REG (2), PTR_REG (1), lsl PTR_LOG_SIZE
+ add PTR_REG (3), PTR_REG (3), PTR_SIZE
+ adrp x16, _rtld_local
+ add PTR_REG (16), PTR_REG (16), :lo12:_rtld_local
+ ldr PTR_REG (0), [x16]
+ bl _dl_init
+ /* Load the finalizer function. */
+ adrp x0, _dl_fini
+ add PTR_REG (0), PTR_REG (0), :lo12:_dl_fini
+ /* Jump to the user's entry point. */
+ mov x16, x21
+ br x16
+END (_start)
--
2.27.0
|
