在AMD的X86-64运算代呼叫指令 [英] operand generation of CALL instruction on x86-64 AMD

问题描述

下面是一个示例程序objdump的输出，

Following is the output of objdump of a sample program,

080483b4 <display>:
 80483b4:       55                      push   %ebp
 80483b5:       89 e5                   mov    %esp,%ebp
 80483b7:       83 ec 18                sub    $0x18,%esp
 80483ba:       8b 45 0c                mov    0xc(%ebp),%eax
 80483bd:       89 44 24 04             mov    %eax,0x4(%esp)
 80483c1:       8d 45 fe                lea    0xfffffffe(%ebp),%eax
 80483c4:       89 04 24                mov    %eax,(%esp)
 80483c7:       e8 ec fe ff ff          call   80482b8 <strcpy@plt>
 80483cc:       8b 45 08                mov    0x8(%ebp),%eax
 80483cf:       89 44 24 04             mov    %eax,0x4(%esp)
 80483d3:       c7 04 24 f0 84 04 08    movl   $0x80484f0,(%esp)
 80483da:       e8 e9 fe ff ff          call   80482c8 <printf@plt>
 80483df:       c9                      leave
 80483e0:       c3                      ret

080483e1 <main>:
 80483e1:       8d 4c 24 04             lea    0x4(%esp),%ecx
 80483e5:       83 e4 f0                and    $0xfffffff0,%esp
 80483e8:       ff 71 fc                pushl  0xfffffffc(%ecx)
 80483eb:       55                      push   %ebp
 80483ec:       89 e5                   mov    %esp,%ebp
 80483ee:       51                      push   %ecx
 80483ef:       83 ec 24                sub    $0x24,%esp
 80483f2:       c7 44 24 04 f3 84 04    movl   $0x80484f3,0x4(%esp)
 80483f9:       08
 80483fa:       c7 04 24 0a 00 00 00    movl   $0xa,(%esp)
 8048401:       e8 ae ff ff ff          call   80483b4 <display>
 8048406:       b8 00 00 00 00          mov    $0x0,%eax
 804840b:       83 c4 24                add    $0x24,%esp
 804840e:       59                      pop    %ecx
 804840f:       5d                      pop    %ebp
 8048410:       8d 61 fc                lea    0xfffffffc(%ecx),%esp

我需要明白的，是我们看到的地址主要有以下 - 8048401，拨打80483b4，但是该机code是 - E8 AE FF FF FF。我看到CALL指令是E8，但如何功能80483b4的地址去获得coded到FFFFFFAE？我做了很多在谷歌搜索，但它并没有返回任何东西。任何人都可以请解释？

What i need to understand, is in main we see the following at address - 8048401, call 80483b4 , however the machine code is - e8 ae ff ff ff. I see that CALL instruction is E8 but how is the address of function 80483b4 getting decoded to FFFFFFAE? I did a lot of search in google but it did not return anything. Can Anyone please explain?

推荐答案

E8为呼叫相对，意思是通过将操作数的下一个指令的地址的目的地址被计算的操作数。该操作数是0xFFFFFFAE，这是负0×52。 0x808406 - 0×52是0x80483b4。

E8 is the operand for "Call Relative", meaning the destination address is computed by adding the operand to the address of the next instruction. The operand is 0xFFFFFFAE, which is negative 0x52. 0x808406 - 0x52 is 0x80483b4.

大多数反汇编有益计算出实际的目标地址，而不是只给你在操作数的相对地址。

Most disassemblers helpfully calculate the actual target address rather than just give you the relative address in the operand.

完整信息，时间：<一href=\"http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-2a-manual.html\">http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-2a-manual.html

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