From mboxrd@z Thu Jan  1 00:00:00 1970
MIME-version: 1.0
Content-transfer-encoding: 7BIT
Content-type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
Message-id: <A6C2015E-B5F6-4E45-A6C0-94C058946D0A@mac.com>
From: Pietro Gagliardi <pietro10@mac.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
In-reply-to: <FDDBD0C9-7A87-4C89-85F9-8242D7B63949@kix.in>
Date: Fri,  2 May 2008 06:21:19 -0400
References: <FDDBD0C9-7A87-4C89-85F9-8242D7B63949@kix.in>
Subject: Re: [9fans] Disassembler?
Topicbox-Message-UUID: 9cc2713a-ead3-11e9-9d60-3106f5b1d025


On May 2, 2008, at 6:14 AM, Anant Narayanan wrote:

> Hi,
>
> Is there a tool available which can convert plan 9 a.out executables
> to plan 9 assembly code? I'd like to know how the C compiler stores
> arguments for a system call on the stack for x86.
>
> 8c -S does not help, since all it displays is: `call print', instead
> of what instructions are actually executed when print is called.
>
> Regards,
> Anant
>
>

8c doesn't use push or pop. It stores values directly onto the stack
with MOVL AX, 4(SP) for the second argument. This implies you'll need
to allocate enough stack space:

	TEXT x, 0, $12

will give you enough for 2 arguments (don't tell me why not 3).

The compilers push arguments left to right every 4 bytes.