Scope of the Tutorial

Runs on bit Linux only.

Writing 64 Bit Assembly on Mac OS X

Runs on bit macOS only. Identify the differences between the two programs.


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Most programs consist of directives followed by one or more sections. Lines can have an optional label. Most lines have an instruction followed by zero or more operands.

Generally, you put code in a section called. Details NASM is an awesome assembler, but assembly language is complex.

assembly - macOS bit System Call Table - Stack Overflow

You need more than a tutorial. You need details. Lots of details. Be ready to consult: The write function takes three arguments, which are described in the following assembly:. As was already pointed out, you need to add 0x to the call number.

Your First Program

There are classes of system calls on OSX. All system calls enter the kernel via the syscall instruction. So that magic number 0x is constructed as:. Apparently you can get that magic number from the kernel sources but not from the developer include files.

Syscalls Part 2. OS X (intel x86-64)

I think this means that Apple really wants you to link against library object files which resolve your system call shim rather than use an inline routine: Arguments are passed in rdi, rsi, rdx, r10, r8 and r9. The syscall number is in the rax register. By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service , privacy policy and cookie policy , and that your continued use of the website is subject to these policies.

Michael Petch Bennett Bennett 6 Technologeeks Technologeeks 4, 17 MichaelPetch idk The write function takes three arguments, which are described in the following assembly: Note that this does not work in general.

Your Answer

Some calls have the same numbers, but most numbers are going to be different. It is a very bad idea to infer OS X system call numbers from Linux system call numbers. Don't do that! Do you know of any macOS system call tables? I don't know if it's accurate, but I found this: