C 如何使用链接器脚本指定特定节的内存地址?
我正在从事一个大型项目,该项目涉及编写一个Perl脚本来转换汇编文件,我试图确定转换后汇编文件的外观,以及编译它们的过程。我一直很难找到一个简单的例子。我从一个简单的程序开始,fib.c。我编译了它,然后添加了一个名为“跳板”的部分C 如何使用链接器脚本指定特定节的内存地址?,c,assembly,ld,C,Assembly,Ld,我正在从事一个大型项目,该项目涉及编写一个Perl脚本来转换汇编文件,我试图确定转换后汇编文件的外观,以及编译它们的过程。我一直很难找到一个简单的例子。我从一个简单的程序开始,fib.c。我编译了它,然后添加了一个名为“跳板”的部分 .file "fib.c" .text .globl fib .type fib, @function fib: .LFB0: .cfi_startproc p
.file "fib.c"
.text
.globl fib
.type fib, @function
fib:
.LFB0:
.cfi_startproc
pushl %ebp
.cfi_def_cfa_offset 8
.cfi_offset 5, -8
movl %esp, %ebp
.cfi_def_cfa_register 5
pushl %ebx
subl $20, %esp
cmpl $0, 8(%ebp)
jne .L2
.cfi_offset 3, -12
movl $1, %eax
jmp .SB1
.LBL1:
jmp .L3
.L2:
cmpl $1, 8(%ebp)
jne .L4
movl $1, %eax
jmp .SB2
.LBL2:
jmp .L3
.L4:
movl 8(%ebp), %eax
subl $1, %eax
movl %eax, (%esp)
call fib
movl %eax, %ebx
movl 8(%ebp), %eax
subl $2, %eax
movl %eax, (%esp)
call fib
addl %ebx, %eax
.L3:
addl $20, %esp
popl %ebx
.cfi_restore 3
popl %ebp
.cfi_def_cfa 4, 4
.cfi_restore 5
ret
.cfi_endproc
.LFE0:
.size fib, .-fib
.section .rodata
.LC0:
.string "Usage: fib <n>\n"
.LC1:
.string "f(%d) = %d\n"
.text
.globl main
.type main, @function
main:
.LFB1:
.cfi_startproc
pushl %ebp
.cfi_def_cfa_offset 8
.cfi_offset 5, -8
movl %esp, %ebp
.cfi_def_cfa_register 5
andl $-16, %esp
subl $32, %esp
cmpl $2, 8(%ebp)
je .L6
movl stderr, %eax
movl %eax, %edx
movl $.LC0, %eax
movl %edx, 12(%esp)
movl $15, 8(%esp)
movl $1, 4(%esp)
movl %eax, (%esp)
call fwrite
movl $1, (%esp)
call exit
.L6:
movl 12(%ebp), %eax
addl $4, %eax
movl (%eax), %eax
movl %eax, (%esp)
call atoi
movl %eax, 24(%esp)
movl 24(%esp), %eax
movl %eax, (%esp)
call fib
movl %eax, 28(%esp)
movl $.LC1, %eax
movl 28(%esp), %edx
movl %edx, 8(%esp)
movl 24(%esp), %edx
movl %edx, 4(%esp)
movl %eax, (%esp)
call printf
movl $0, (%esp)
call exit
.cfi_endproc
.LFE1:
.size main, .-main
.section .springboard,"ax",@progbits
.SB2:
jmp .LBL2
.SB1:
jmp .LBL1
.LFE2:
.size .springboard, .-.springboard
.ident "GCC: (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3"
.section .note.GNU-stack,"",@progbits
我遇到的问题是GNU链接器脚本。我希望能够把跳板部分放在一个特定的内存地址。以下是脚本:
OUTPUT_FORMAT(elf32-i386)
ENTRY(main)
SB_START = 0x08148508;
SECTIONS
{
. = SB_START;
.springboard : { *(.springboard) }
}
Sections:
Idx Name Size VMA LMA File off Algn
0 .interp 00000013 08048134 08048134 00000134 2**0
CONTENTS, ALLOC, LOAD, READONLY, DATA
1 .note.ABI-tag 00000020 08048148 08048148 00000148 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
2 .hash 00000038 08048168 08048168 00000168 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
3 .dynsym 00000090 080481a0 080481a0 000001a0 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
4 .dynstr 00000064 08048230 08048230 00000230 2**0
CONTENTS, ALLOC, LOAD, READONLY, DATA
5 .gnu.version 00000012 08048294 08048294 00000294 2**1
CONTENTS, ALLOC, LOAD, READONLY, DATA
6 .gnu.version_r 00000020 080482a8 080482a8 000002a8 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
7 .rel.dyn 00000010 080482c8 080482c8 000002c8 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
8 .rel.plt 00000030 080482d8 080482d8 000002d8 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
9 .init 00000024 08048308 08048308 00000308 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
10 .plt 00000070 08048330 08048330 00000330 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
11 .text 00000188 080483a0 080483a0 000003a0 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
12 .fini 00000015 08048528 08048528 00000528 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
13 .rodata 00000024 08048540 08048540 00000540 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
14 .eh_frame 000000e0 08048564 08048564 00000564 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
15 .dynamic 000000c8 08049644 08049644 00000644 2**2
CONTENTS, ALLOC, LOAD, DATA
16 .got 00000004 0804970c 0804970c 0000070c 2**2
CONTENTS, ALLOC, LOAD, DATA
17 .got.plt 00000024 08049710 08049710 00000710 2**2
CONTENTS, ALLOC, LOAD, DATA
18 .data 00000004 08049734 08049734 00000734 2**2
CONTENTS, ALLOC, LOAD, DATA
19 .bss 00000004 08049738 08049738 00000738 2**2
ALLOC
20 .comment 0000002a 00000000 00000000 00001512 2**0
CONTENTS, READONLY
21 .springboard 0000000a 08148508 08148508 00001508 2**0
CONTENTS, ALLOC, LOAD, READONLY, CODE
我已经在这上面呆了一段时间,尝试了一些不同的东西,我对链接器脚本非常陌生,所以也许这对你们中的一些人来说会很容易
使用objdump-x fib查看没有链接器脚本的部分
Sections:
Idx Name Size VMA LMA File off Algn
0 .interp 00000013 08048114 08048114 00000114 2**0
CONTENTS, ALLOC, LOAD, READONLY, DATA
1 .note.ABI-tag 00000020 08048128 08048128 00000128 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
2 .hash 00000038 08048148 08048148 00000148 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
3 .dynsym 00000090 08048180 08048180 00000180 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
4 .dynstr 00000064 08048210 08048210 00000210 2**0
CONTENTS, ALLOC, LOAD, READONLY, DATA
5 .gnu.version 00000012 08048274 08048274 00000274 2**1
CONTENTS, ALLOC, LOAD, READONLY, DATA
6 .gnu.version_r 00000020 08048288 08048288 00000288 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
7 .rel.dyn 00000010 080482a8 080482a8 000002a8 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
8 .rel.plt 00000030 080482b8 080482b8 000002b8 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
9 .init 00000024 080482e8 080482e8 000002e8 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
10 .plt 00000070 08048310 08048310 00000310 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
11 .text 00000188 08048380 08048380 00000380 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
12 .springboard 0000000a 08048508 08048508 00000508 2**0
CONTENTS, ALLOC, LOAD, READONLY, CODE
13 .fini 00000015 08048514 08048514 00000514 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
14 .rodata 00000024 0804852c 0804852c 0000052c 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
15 .eh_frame 000000e0 08048550 08048550 00000550 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
16 .dynamic 000000c8 08049630 08049630 00000630 2**2
CONTENTS, ALLOC, LOAD, DATA
17 .got 00000004 080496f8 080496f8 000006f8 2**2
CONTENTS, ALLOC, LOAD, DATA
18 .got.plt 00000024 080496fc 080496fc 000006fc 2**2
CONTENTS, ALLOC, LOAD, DATA
19 .data 00000004 08049720 08049720 00000720 2**2
CONTENTS, ALLOC, LOAD, DATA
20 .bss 00000004 08049724 08049724 00000724 2**2
ALLOC
21 .comment 0000002a 00000000 00000000 00000724 2**0
CONTENTS, READONLY
然后是脚本:
OUTPUT_FORMAT(elf32-i386)
ENTRY(main)
SB_START = 0x08148508;
SECTIONS
{
. = SB_START;
.springboard : { *(.springboard) }
}
Sections:
Idx Name Size VMA LMA File off Algn
0 .interp 00000013 08048134 08048134 00000134 2**0
CONTENTS, ALLOC, LOAD, READONLY, DATA
1 .note.ABI-tag 00000020 08048148 08048148 00000148 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
2 .hash 00000038 08048168 08048168 00000168 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
3 .dynsym 00000090 080481a0 080481a0 000001a0 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
4 .dynstr 00000064 08048230 08048230 00000230 2**0
CONTENTS, ALLOC, LOAD, READONLY, DATA
5 .gnu.version 00000012 08048294 08048294 00000294 2**1
CONTENTS, ALLOC, LOAD, READONLY, DATA
6 .gnu.version_r 00000020 080482a8 080482a8 000002a8 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
7 .rel.dyn 00000010 080482c8 080482c8 000002c8 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
8 .rel.plt 00000030 080482d8 080482d8 000002d8 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
9 .init 00000024 08048308 08048308 00000308 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
10 .plt 00000070 08048330 08048330 00000330 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
11 .text 00000188 080483a0 080483a0 000003a0 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
12 .fini 00000015 08048528 08048528 00000528 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
13 .rodata 00000024 08048540 08048540 00000540 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
14 .eh_frame 000000e0 08048564 08048564 00000564 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
15 .dynamic 000000c8 08049644 08049644 00000644 2**2
CONTENTS, ALLOC, LOAD, DATA
16 .got 00000004 0804970c 0804970c 0000070c 2**2
CONTENTS, ALLOC, LOAD, DATA
17 .got.plt 00000024 08049710 08049710 00000710 2**2
CONTENTS, ALLOC, LOAD, DATA
18 .data 00000004 08049734 08049734 00000734 2**2
CONTENTS, ALLOC, LOAD, DATA
19 .bss 00000004 08049738 08049738 00000738 2**2
ALLOC
20 .comment 0000002a 00000000 00000000 00001512 2**0
CONTENTS, READONLY
21 .springboard 0000000a 08148508 08148508 00001508 2**0
CONTENTS, ALLOC, LOAD, READONLY, CODE
我想了解更多关于我可以用链接器脚本做什么以及如何使用链接器脚本的信息。我读过其他的问题和教程,但还是很困惑。我不完全理解所有的部分是什么以及它们应该放在哪里,我想我应该从一些简单的东西开始,然后添加一个,但是我可能需要更详细地理解一些东西才能使它发挥作用。知道如何修复我的链接器脚本吗?关于这个主题,我还需要知道什么?谢谢
在Ubuntu机器上工作,我只关注32位程序。你提到过吗?第3章确实解释了链接器脚本。不过,它不会赢得任何最佳手册奖。:)
您看到的部分是各种数据(.data、.bss、.rodata)和代码(.text、.init、.fini)部分。更多细节。还可以尝试用谷歌搜索部分名称。问题在于行条目(main)
。这表示程序将在该点启动
Argc和Argv由crt1.o设置,如下所述:
这意味着我们根本不需要进入点。如果我们把它作为我们的切入点,参数将无法正确设置。o也将调用main。链接器脚本现在如下所示:
OUTPUT_FORMAT(elf32-i386)
SECTIONS
{
. = 0x08148508;
.springboard : { *(.springboard) }
}
你不太清楚问题是什么。你想修什么?你的跳板确实到达了要求的地址。谢谢!我一直在读那份文件。我想问题是,当程序使用链接器脚本构建时,它不能正常运行。程序应该有一个参数,所以我可以用/fib 3
调用它。如果没有参数,它将显示用法:fib
。但是,当使用我的链接器脚本运行时,它总是显示用法。在链接器脚本中,我必须做些什么才能让参数工作吗?我找到了修复方法。问题是我需要取出ENTRY(main)
。o设置argc和argv并调用main,听起来像:完全错过了链接器脚本中的那个条目。你可能应该创造一个答案并接受它。