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From: Rusty Russell <rusty@rustcorp.com.au>
To: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andrew Honig <ahonig@google.com>, Michal Marek <mmarek@suse.cz>,
	"x86@kernel.org" <x86@kernel.org>, Tejun Heo <tj@kernel.org>,
	Tony Luck <tony.luck@intel.com>,
	Fenghua Yu <fenghua.yu@intel.com>,
	linux-ia64@vger.kernel.org, keescook@chromium.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] kallsyms: handle special absolute symbols
Date: Fri, 07 Mar 2014 03:37:00 +0000	[thread overview]
Message-ID: <8761nqzo4z.fsf@rustcorp.com.au> (raw)
In-Reply-To: <1394152324-26304-3-git-send-email-keescook@chromium.org>

Kees Cook <keescook@chromium.org> writes:
> This forces the entire per_cpu range to be reported as absolute without
> losing their linker symbol types. Without this, the variables are
> incorrectly shown as relocated under kASLR.

I like these patches, thanks!

This one's a bit broken, since the zero-based __per_cpu_start/end thing
is an x86-64-ism.  You really do want them relocated on other
platforms, so I think you'll need do make this conditional via
a --per-cpu-absolute flag to kallsyms (which x86-64 would set).

Dumb Q: why don't we actually present these symbols as absolute in
/proc/kallsyms?  Seems like it would be clearer...

Thanks,
Rusty.

WARNING: multiple messages have this Message-ID (diff)
From: Rusty Russell <rusty@rustcorp.com.au>
To: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andrew Honig <ahonig@google.com>, Michal Marek <mmarek@suse.cz>,
	"x86\@kernel.org" <x86@kernel.org>, Tejun Heo <tj@kernel.org>,
	Tony Luck <tony.luck@intel.com>,
	Fenghua Yu <fenghua.yu@intel.com>,
	linux-ia64@vger.kernel.org, keescook@chromium.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] kallsyms: handle special absolute symbols
Date: Fri, 07 Mar 2014 13:55:00 +1030	[thread overview]
Message-ID: <8761nqzo4z.fsf@rustcorp.com.au> (raw)
In-Reply-To: <1394152324-26304-3-git-send-email-keescook@chromium.org>

Kees Cook <keescook@chromium.org> writes:
> This forces the entire per_cpu range to be reported as absolute without
> losing their linker symbol types. Without this, the variables are
> incorrectly shown as relocated under kASLR.

I like these patches, thanks!

This one's a bit broken, since the zero-based __per_cpu_start/end thing
is an x86-64-ism.  You really do want them relocated on other
platforms, so I think you'll need do make this conditional via
a --per-cpu-absolute flag to kallsyms (which x86-64 would set).

Dumb Q: why don't we actually present these symbols as absolute in
/proc/kallsyms?  Seems like it would be clearer...

Thanks,
Rusty.

  reply	other threads:[~2014-03-07  3:37 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-07  0:32 [PATCH 0/2] kallsyms: handle special absolute symbols Kees Cook
2014-03-07  0:32 ` Kees Cook
2014-03-07  0:32 ` [PATCH 1/2] kallsyms: generalize address range checking Kees Cook
2014-03-07  0:32   ` Kees Cook
2014-03-07  0:32 ` [PATCH 2/2] kallsyms: handle special absolute symbols Kees Cook
2014-03-07  0:32   ` Kees Cook
2014-03-07  3:25   ` Rusty Russell [this message]
2014-03-07  3:37     ` Rusty Russell
2014-03-07  5:42     ` Kees Cook
2014-03-07  5:42       ` Kees Cook
2014-03-07 12:25   ` Tejun Heo
2014-03-07 12:25     ` Tejun Heo

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