[英]How to use use as in linux with assembly language
I am studying Linux kernel, so I have to read some assembly code. 我正在研究Linux内核,所以我必须阅读一些汇编代码。 Here is a sample code
这是一个示例代码
SYSWRITE=4
.globl mywrite,myadd
.text
mywrite:
pushl %ebp
movl %esp,%ebp
pushl %ebx
movl 8(%ebp),%ebx
movl 12(%ebp),%ecx
movl 16(%ebp),%edx
movl $SYSWRITE,%eax
int $0x80
popl %ebx
movl %ebp,%esp
popl %ebp
ret
myadd:
pushl %ebp
movl %esp,%ebp
movl 8(%ebp),%eax
movl 12(%ebp),%edx
xorl %ecx,%ecx
addl %eax,%edx
jo 1f
movl 16(%ebp),%eax
movl %edx,(%eax)
incl %ecx
1:
movl %ecx,%eax
movl %ebp,%esp
popl %ebp
ret
I use the as in this way 我以这种方式使用as
"as -o callee.o callee.s" “as -o callee.o callee.s”
to compile it,but it fails with a message saying something like this 编译它,但它失败了一条消息说这样的事情
"callee.s|5| Error: suffix or operands invalid for `push'" “callee.s | 5 |错误:后缀或操作数对于'push'无效”
You're probably on a 64-bit machine, so your as
defaults to 64-bit. 你可能在64位机器上,所以你
as
默认为64位。 Since you have 32-bit code, you want to use: 由于您有32位代码,因此您希望使用:
as -32 -o callee.o callee.s
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