From: David Laight <David.Laight@ACULAB.COM>
To: 'Brian Gerst' <brgerst@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>, "H . Peter Anvin" <hpa@zytor.com>,
"Peter Zijlstra" <peterz@infradead.org>,
Uros Bizjak <ubizjak@gmail.com>
Subject: RE: [PATCH v2 00/11] x86-64: Stack protector and percpu improvements
Date: Sun, 29 Oct 2023 21:42:41 +0000 [thread overview]
Message-ID: <a094c7da294a4827994af72249262593@AcuMS.aculab.com> (raw)
In-Reply-To: <20231026160100.195099-1-brgerst@gmail.com>
From: Brian Gerst
> Sent: 26 October 2023 17:01
>
> Currently, x86-64 uses an unusual percpu layout, where the percpu section
> is linked at absolute address 0. The reason behind this is that older GCC
> versions placed the stack protector (if enabled) at a fixed offset from the
> GS segment base. Since the GS segement is also used for percpu variables,
> this forced the current layout.
>
> GCC since version 8.1 supports a configurable location for the stack
> protector value, which allows removal of the restriction on how the percpu
> section is linked. This allows the percpu section to be linked
> normally, like most other architectures. In turn, this allows removal
> of code that was needed to support the zero-based percpu section.
I didn't think the minimum gcc version was anything like 8.1.
I'm using 7.5.0 and I don't think that is the oldest version.
David
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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2023-10-29 21:42 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-26 16:00 [PATCH v2 00/11] x86-64: Stack protector and percpu improvements Brian Gerst
2023-10-26 16:00 ` [PATCH v2 01/11] x86/stackprotector/32: Remove stack protector test script Brian Gerst
2023-10-26 17:59 ` Uros Bizjak
2023-10-26 16:00 ` [PATCH v2 02/11] x86/stackprotector/64: " Brian Gerst
2023-10-26 18:06 ` Uros Bizjak
2023-10-26 16:00 ` [PATCH v2 03/11] x86/boot: Disable stack protector for early boot code Brian Gerst
2023-10-26 16:00 ` [PATCH v2 04/11] x86/pvh: Use fixed_percpu_data for early boot GSBASE Brian Gerst
2023-10-26 16:00 ` [PATCH v2 05/11] x86/stackprotector/64: Convert stack protector to normal percpu variable Brian Gerst
2023-10-26 18:16 ` Uros Bizjak
2023-10-29 1:26 ` kernel test robot
2023-10-29 6:56 ` Brian Gerst
2023-10-29 17:00 ` Brian Gerst
2023-10-30 15:24 ` Nick Desaulniers
2023-10-30 17:19 ` Brian Gerst
2023-11-01 21:21 ` Fangrui Song
2023-10-26 16:00 ` [PATCH v2 06/11] x86/percpu/64: Remove fixed_percpu_data Brian Gerst
2023-10-26 18:28 ` Uros Bizjak
2023-10-26 16:00 ` [PATCH v2 07/11] x86/percpu/64: Use relative percpu offsets Brian Gerst
2023-10-26 18:47 ` Uros Bizjak
2023-10-27 2:09 ` Brian Gerst
2023-10-27 6:09 ` Uros Bizjak
2023-10-26 16:00 ` [PATCH v2 08/11] x86/boot/64: Remove inverse relocations Brian Gerst
2023-10-26 16:00 ` [PATCH v2 09/11] x86/percpu/64: Remove INIT_PER_CPU macros Brian Gerst
2023-10-26 18:48 ` Uros Bizjak
2023-10-26 16:00 ` [PATCH v2 10/11] percpu: Remove PER_CPU_FIRST_SECTION Brian Gerst
2023-10-26 18:51 ` Uros Bizjak
2023-10-26 16:01 ` [PATCH v2 11/11] kallsyms: Remove KALLSYMS_ABSOLUTE_PERCPU Brian Gerst
2023-10-29 21:42 ` David Laight [this message]
2023-10-29 23:19 ` [PATCH v2 00/11] x86-64: Stack protector and percpu improvements Brian Gerst
2023-10-30 8:06 ` Uros Bizjak
2023-10-30 9:05 ` David Laight
2023-10-30 9:10 ` Uros Bizjak
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