[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <202402231550.80B97C8E@keescook>
Date: Fri, 23 Feb 2024 15:52:00 -0800
From: Kees Cook <keescook@...omium.org>
To: Jann Horn <jannh@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] x86/boot: avoid recompiling kaslr.c for incremental
rebuilds
On Tue, Feb 20, 2024 at 08:21:44PM +0100, Jann Horn wrote:
> Currently, every kernel rebuild needs to compile kaslr.c again because
> UTS_VERSION changes on every rebuild.
> Move the build string into a separate object file to speed things up.
>
> Signed-off-by: Jann Horn <jannh@...gle.com>
> ---
> arch/x86/boot/compressed/dynamic_vars.c | 8 ++++++++
> arch/x86/boot/compressed/dynamic_vars.h | 3 +++
> arch/x86/boot/compressed/kaslr.c | 10 ++--------
> 3 files changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/boot/compressed/dynamic_vars.c b/arch/x86/boot/compressed/dynamic_vars.c
> index cda64ff4b6da..15a57fbb05e3 100644
> --- a/arch/x86/boot/compressed/dynamic_vars.c
> +++ b/arch/x86/boot/compressed/dynamic_vars.c
> @@ -1,9 +1,17 @@
> // SPDX-License-Identifier: GPL-2.0
> #include <linux/const.h>
> #include "dynamic_vars.h"
> +#include <generated/compile.h>
> +#include <generated/utsrelease.h>
> +#include <generated/utsversion.h>
> #include "../voffset.h"
>
> const unsigned long vo__text = VO__text;
> const unsigned long vo___bss_start = VO___bss_start;
> const unsigned long vo__end = VO__end;
> const unsigned long kernel_total_size = VO__end - VO__text;
> +
> +/* Simplified build-specific string for starting entropy. */
> +const char build_str[] = UTS_RELEASE " (" LINUX_COMPILE_BY "@"
> + LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION;
> +unsigned long build_str_len = sizeof(build_str)-1;
This can be const too, yes? (Also, you didn't want to include the
trailing NUL in the xor?
Otherwise, yeah, I like this whole series.
--
Kees Cook
Powered by blists - more mailing lists