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From: Alexander Popov <alex.popov@linux.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: kernel-hardening@lists.openwall.com, keescook@chromium.org,
	pageexec@freemail.hu, spender@grsecurity.net, tycho@docker.com,
	Laura Abbott <labbott@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Andy Lutomirski <luto@amacapital.net>,
	x86@kernel.org, Linus Torvalds <torvalds@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: [kernel-hardening] Re: [PATCH RFC v4 1/3] gcc-plugins: Add STACKLEAK erasing the kernel stack at the end of syscalls
Date: Fri, 13 Oct 2017 20:03:59 +0300	[thread overview]
Message-ID: <ac934200-74e0-3e0d-fd14-dff64197c03a@linux.com> (raw)
In-Reply-To: <20171005072751.lhf7kamzfw4sdhbo@gmail.com>

Hello Ingo,

On 05.10.2017 10:27, Ingo Molnar wrote:
> - The GCC plugin adds instrumentation in form of extra 'track_stack()' and
>   'check_alloca()' calls. Could you please provide a frequency analysis of the
>   impact of this: x86-64 defconfig vmlinux size before/after the patch, and the
>   number of instrumentation function calls inserted, compared to the number of
>   functions?

Size of vmlinux (x86_64_defconfig):
 file size:
  - STACKLEAK disabled: 35014784 bytes
  - STACKLEAK enabled: 35044952 bytes (+0.086%)
 .text section size (calculated by size utility):
  - STACKLEAK disabled: 10752983
  - STACKLEAK enabled: 11062221 (+2.876%)

The readelf utility shows 45602 functions in vmlinux.

The STACKLEAK gcc plugin inserted 36 check_alloca() calls and 1265 track_stack()
calls (42274 calls are inserted during GIMPLE pass and 41009 calls are deleted
during RTL pass). So 2.853% of functions are instrumented.

I will add this information to the cover letter of the 5'th version, which I'm
currently preparing.

Best regards,
Alexander

  parent reply	other threads:[~2017-10-13 17:03 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-04 22:55 [kernel-hardening] [PATCH RFC v4 0/3] Introduce the STACKLEAK feature and a test for it Alexander Popov
2017-10-04 22:55 ` [kernel-hardening] [PATCH RFC v4 1/3] gcc-plugins: Add STACKLEAK erasing the kernel stack at the end of syscalls Alexander Popov
2017-10-04 23:31   ` [kernel-hardening] " Kees Cook
2017-10-05  7:27   ` Ingo Molnar
2017-10-05 12:31     ` Alexander Popov
2017-10-10 22:33       ` Laura Abbott
2017-10-13 17:03     ` Alexander Popov [this message]
2017-10-04 22:55 ` [kernel-hardening] [PATCH RFC v4 2/3] lkdtm: Add a test for STACKLEAK Alexander Popov
2017-10-04 22:55 ` [kernel-hardening] [PATCH RFC v4 3/3] doc: self-protection: Add information about STACKLEAK feature Alexander Popov
2017-10-05  4:40 ` [kernel-hardening] Re: [PATCH RFC v4 0/3] Introduce the STACKLEAK feature and a test for it Andy Lutomirski
2017-10-11  1:19 ` Laura Abbott
2017-10-11  2:31   ` Andy Lutomirski
2017-10-11 16:29     ` Alexander Popov
2017-10-13 17:26       ` Andy Lutomirski
2017-10-21 21:56         ` Alexander Popov

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