linux-kernel - RE: How do I force an IBT trap in a demo kernel module?

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Message-ID: <8ee1b8453e614b5b930d13c2f3747221@AcuMS.aculab.com>
Date:   Thu, 1 Jun 2023 08:04:43 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     "'Preble, Adam C'" <adam.c.preble@...el.com>,
        Pavel Machek <pavel@....cz>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: How do I force an IBT trap in a demo kernel module?

From: Preble, Adam C
> Sent: 01 June 2023 00:02
> 
> It looked to me like I was getting the indirect jump just fine with what I already was doing. Sure, I
> made the instruction pointer volatile and static, but nothing changed just from that.

This ought to compile to code that does what you want..

void func(void) {}

void (*func_ptr)(void) = func;

void test(void)
{
	void (*ptr)(void) = (void *)func_ptr + 4;

	ptr();
}

See https://godbolt.org/z/o8cedv3d4 but that doesn't have the option
that generated the endbra.

	David

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