64位问题:尝试使用内联程序集将值从%rsp复制到临时变量

I'm taking an operating systems design class in which they have given us a microkernel written in C that we're building on top of. The kernel seems to have been designed with 32-bit machines in mind and I'm running snow leopard. So a friend in the class and I have been trying to hack it into 64-bit addressing.

我参加了一个操作系统设计课程，他们给了我们一个用C语言写的微内核，我们正在构建它。内核似乎是用32位机器设计的，我正在运行snow leopard。所以我的一个朋友，我一直想把它变成64位寻址。

The biggest issue seems to be one line of code, where inline assembly is utilized to copy the current stack pointer into a temporary variable used by the dispatcher:

最大的问题似乎是一行代码，使用内联程序集将当前堆栈指针复制到dispatcher使用的临时变量中:

#define SET_STACK(s) asm("movl temp,%esp");

Naturally, the compiler spits back errors at me because %esp is a 32-bit register.

当然，编译器会向我输出错误，因为%esp是一个32位寄存器。

/var/folders/0A/0AVWZC-5HhOg6twWZBlDgU+++TI/-Tmp-//cckS2oq7.s:523:32-bit absolute addressing is not supported for x86-64
/var/folders/0A/0AVWZC-5HhOg6twWZBlDgU+++TI/-Tmp-//cckS2oq7.s:523:cannot do signed 4 byte relocation

So I replaced it with %rsp because it's the 64-bit stack pointer register (and I think just %sp works as well, I read somewhere else on here that GAS is smart enough to put the right prefix). After replacing %esp with %rsp, I get this error:

因此我用%rsp替换了它，因为它是64位堆栈指针寄存器(我认为仅仅%sp就可以工作，我在这里的其他地方读到过，GAS足够聪明，可以使用正确的前缀)。在用%rsp替换%esp后，我得到了这个错误:

/var/folders/0A/0AVWZC-5HhOg6twWZBlDgU+++TI/-Tmp-//cc8TLdjH.s:523:Incorrect register `%sp' used with `l' suffix

Now, I'm a bit at a loss because I'm not really experienced with assembler. I've tried replacing movl with mov, and movq, but nothing seems to work. Which leads me to believe that maybe tempis the wrong size?

现在，我有点不知所措了，因为我对汇编程序没有经验。我试过用mov和movq来代替movl，但似乎什么都不做。这让我相信也许tempis的尺寸不对?

Temp is a global variable, declared like so:

Temp是一个全局变量，声明如下:

void* temp;   // temp pointer used in dispatcher

I wrote a quick program to print out the sizes of different datatypes, and it seems like void* in x86-64 are 8 bytes in size, which should be the right size, right?

我写了一个快速的程序来打印不同数据类型的大小，在x86-64中，void*的大小是8字节，应该是正确的大小，对吧?

Anyway, obviously I don't expect anyone to solve this problem for me, but any tips that might point me in the right direction would be much appreciated!

不管怎样，很明显，我不希望任何人能帮我解决这个问题，但是任何能让我找到正确方向的建议都将非常感谢!

2 个解决方案

#1

You need to use movq for 64bit moves.

需要使用movq进行64位移动。

Here is a snippet of assembly doing some SSE work from one of my projects (part of a train simulator), The commented lines are 32bit intel asm, uncommented is 64bit AT&T.

这里是一个程序集，在我的一个项目(火车模拟器的一部分)中做一些SSE工作，注释的行是32位intel asm，未注释的是64位AT&T。

asm(
        //mykda calculation
        //mov eax, dword ptr [train_traction_ptr]
        //movaps xmm0, xmmword ptr [eax] //train_traction[i] + forceFront
        "movq %0, %%rax\n\t"
        "movaps (%%rax), %%xmm0\n\t"

        //mov eax, dword ptr [local_fgrr_ptr]
        //movaps xmm1, xmmword ptr [rax]
        //addps xmm0, xmm1
        "movq %1, %%rax\n\t"
        "movaps (%%rax), %%xmm1\n\t"
        "addps %%xmm1, %%xmm0\n\t"

        ... );

After comment I looked further and found that all 64bit OSX code has to be position independant.

在评论之后，我进一步发现所有64位OSX代码都必须与位置无关。

Haven't got a Mac to test, but

我还没有测试的Mac，但是。

asm ("movq temp(%rip),%rsp");

Should work. If not, you need to use the appropriate PIC addressing for temp for your assembler.

应该工作。如果不是，则需要为汇编程序使用适当的临时图寻址。

#2

The line you've shown doesn't copy the value from %esp into temp - it does the opposite (as the SET_STACK implies). AT&T syntax is src, dest.

您所显示的行不会将%esp中的值复制到temp中——它会执行相反的操作(正如SET_STACK所示)。AT&T语法是src, dest。

A simple asm("mov temp, %rsp"); should compile.

一个简单的asm(“mov temp， %rsp”);应该编译。

#1