调用GAS equ'd符号 [英] Calling equ'd symbols in GAS

问题描述

下面是一个小的程序NASM：

  [BITS 64]
        [ORG 0x0000000000200000]        b_print_newline EQU 0x0000000000100040开始：
        电话b_print_newline        RET
 

组装起来：

  $ NASM -f斌PR-NL-a.asm -o pr-nl-a.app
 

拆解：

  $ objdump的-D -b二进制-m i386的：X86-64 pr-nl-a.app
pr-nl-a.app：文件格式的二进制
段.data拆卸：0000000000000000＆LT;。数据计算值：
   0：E8 3B 00 F0 FF callq 0xfffffffffff00040
   5：C3 retq
 

下面是一个GAS版本：

  .SET b_print_newline，0x0000000000100040        。文本        。全球_start_开始：        电话b_print_newline        RET
 

汇编并链接：

  $为-o PR-NL-B.O PR-NL-b.s
$ LD -Ttext 200000 --oformat二进制-o pr-nl-b.app PR-NL-B.O
 

拆解：

  $ objdump的-D -b二进制-m i386的：X86-64 pr-nl-b.app
pr-nl-b.app：文件格式的二进制
段.data拆卸：0000000000000000＆LT;。数据计算值：
   0：FF 14 25 40 0​​0 10 00 callq * 0x100040
   7：C3 retq
 

正如你所看到的，反汇编code略有不同。在code为呼叫在NASM：

  0：E8 3B 00 F0 FF callq 0xfffffffffff00040
 

VS气：

  0：FF 14 25 40 0​​0 10 00 callq * 0x100040
 

有关如何正确实施GAS版本有什么建议？

下面是该程序在FASM：

  b_print_newline EQU 0x0000000000100040        use64
        组织0x0000000000200000启动：来电b_print_newline
        RET
 

它做正确的事：

  $ objdump的-D -b二进制-m i386的：X86-64 pr-nl-c.apppr-nl-c.app：文件格式的二进制
段.data拆卸：0000000000000000＆LT;。数据计算值：
   0：E8 3B 00 F0 FF callq 0xfffffffffff00040
   5：C3 retq
 

解决方案

添加.ORG 0x0000000000200000到燃气文件。

Here's a small NASM program:

        [BITS 64]
        [ORG 0x0000000000200000]

        b_print_newline equ 0x0000000000100040

start:
        call b_print_newline

        ret

Assemble it:

$ nasm -f bin pr-nl-a.asm -o pr-nl-a.app

Disassemble it:

$ objdump -D -b binary -m i386:x86-64 pr-nl-a.app 
pr-nl-a.app:     file format binary


Disassembly of section .data:

0000000000000000 <.data>:
   0:   e8 3b 00 f0 ff          callq  0xfffffffffff00040
   5:   c3                      retq

Here's a GAS version:

        .set b_print_newline , 0x0000000000100040

        .text

        .global _start

_start:

        call b_print_newline

        ret

Assemble and link it:

$ as -o pr-nl-b.o pr-nl-b.s
$ ld -Ttext 200000 --oformat binary -o pr-nl-b.app pr-nl-b.o

Disassemble it:

$ objdump -D -b binary -m i386:x86-64 pr-nl-b.app 
pr-nl-b.app:     file format binary


Disassembly of section .data:

0000000000000000 <.data>:
   0:   ff 14 25 40 00 10 00    callq  *0x100040
   7:   c3                      retq

As you can see, the disassembled code differs slightly. The code for call in NASM:

0:  e8 3b 00 f0 ff          callq  0xfffffffffff00040

vs GAS:

0:  ff 14 25 40 00 10 00    callq  *0x100040

Any suggestions for how to implement the GAS version properly?

Here's the program in FASM:

        b_print_newline equ 0x0000000000100040

        use64
        org 0x0000000000200000

start:  call b_print_newline
        ret

It does the right thing:

$ objdump -D -b binary -m i386:x86-64 pr-nl-c.app 

pr-nl-c.app:     file format binary


Disassembly of section .data:

0000000000000000 <.data>:
   0:   e8 3b 00 f0 ff          callq  0xfffffffffff00040
   5:   c3                      retq

解决方案

Add ".org 0x0000000000200000" to the GAS file.

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