From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <b89cf29d8e335a2f6fb2b3c529ea5a94@felloff.net>
Date: Thu, 15 May 2014 22:16:56 +0200
From: cinap_lenrek@felloff.net
To: 9fans@9fans.net
In-Reply-To: <a877460eee41ee469461a7c848180901@mikro.quanstro.net>
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Subject: Re: [9fans] linking a program to run at a high address
Topicbox-Message-UUID: e68c2108-ead8-11e9-9d60-3106f5b1d025

because the immidiate to CALL instruction is 32bit which get sign
extended to 64bit. but the PC *is* 64bit. its just not that easy
to call directly.

#include <u.h>
#include <libc.h>

void
jump(void *p)
{
	((void**)&p)[-1] = p;
}

void
main(int argc, char *argv[])
{
	char code[8];

	code[0] = 0xCC; /* breakpoint */
	jump(code);
}

--
cinap