linux-kernel - Re: [PATCH 4/4] drivers/misc: make kgdbts.c slightly more explicitly non-modular

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Date:	Mon, 10 Aug 2015 12:22:50 -0500
From:	Jason Wessel <jason.wessel@...driver.com>
To:	Paul Gortmaker <paul.gortmaker@...driver.com>,
	<linux-kernel@...r.kernel.org>
CC:	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<kgdb-bugreport@...ts.sourceforge.net>
Subject: Re: [PATCH 4/4] drivers/misc: make kgdbts.c slightly more explicitly
 non-modular

On 08/08/2015 03:35 PM, Paul Gortmaker wrote:
> The Kconfig currently controlling compilation of this code is:
>
> lib/Kconfig.kgdb:config KGDB_TESTS
> lib/Kconfig.kgdb:       bool "KGDB: internal test suite"
>
> ...meaning that it currently is not being built as a module by anyone.
>
> Lets remove the modular code that is essentially orphaned, so that
> when reading the driver there is no doubt it is builtin-only.
>
> Since module_init translates to device_initcall in the non-modular
> case, the init ordering remains unchanged with this commit.
>
> We also delete the MODULE_LICENSE tag etc. since all that information
> is already contained at the top of the file in the comments.
>
> We can't remove the module.h include since we've kept the use of
> module_param in this file for now.

This is correct, if you remove that there is no way to invoke the test suite later on at run time.

I tried out the patch and it works fine with no regressions.

Unrelated to this it seems there is a problem with the read/write of the break points when crossing the point where the kernel write protects the read-only data.  Basically, the break point is implanted into the code page, which is made read-only, and then it can no longer be removed.  What we typically do in that case "after read-only pages are established", is to use COW pages for the break points.  I'll have to look further into what if anything we might have to do about it. At least the emergency printk logic worked to show there is a problem. :-)

Acked-by: Jason Wessel <jason.wessel@...driver.com>

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