使用NASM加载符号的地址吗? [英] Load the address of a symbol using NASM?

问题描述

我有一些需要在OS X(x86-64)中加载C符号的程序集.使用x86，您可以这样做:

I have some assembly that needs to load a C symbol in OS X (x86-64). With x86, the way you do this is:

mov rax, some_symbol_name

但是，对于x86-64，这会导致链接警告:

However, with x86-64, this causes a link warning:

ld:警告:禁用PIE.在代码签名的PIE中不允许绝对寻址(也许是-mdynamic-no-pic)，但是在Test2.o的_main中使用.
要解决此警告，请不要使用-mdynamic-no-pic进行编译，也不要使用-Wl，-no_pie

ld: warning: PIE disabled. Absolute addressing (perhaps -mdynamic-no-pic) not allowed in code signed PIE, but used in _main from Test2.o.
To fix this warning, don't compile with -mdynamic-no-pic or link with -Wl,-no_pie

注意:我知道PIE是什么，并且我不想禁用它.这是我将符号地址加载到寄存器中的其他一些尝试:

Note: I know what PIE is, and I don't want to disable it. Here are some of my other attempts to load the symbol address into a register:

movq rax, some_symbol_name          ; Link warning
lea rax, [rel some_symbol_name]     ; No link warning, but doesn't always get correct address

我真的很困惑这个(貌似)简单的问题.我已经看过GAS的反汇编，它似乎正在按照上述lea的方式进行操作，但是我无法让NASM生成正确的代码.

I'm really stumped on this (seemingly) simple problem. I've looked at the GAS disassembly, and it seems to be doing something along the lines of the lea above, but I can't get NASM to generate the right code.

供参考，这是GAS生成的汇编代码:

For reference, this is the assembly code generated by GAS:

leaq    some_symbol_name(%rip), %rax

推荐答案

您要强制NASM使用RIP相对寻址.请执行以下一项操作:

You want to force NASM to use RIP relative addressing. Do one of:

lea rax, [rel some_symbol_name]

或:

default rel
lea rax, [some_symbol_name]

如果这不起作用，请张贴由NASM和GAS生成的机器代码.

If this doesn't work, post the machine code generated by both NASM and GAS.

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