From: Brian Gerst <brgerst@gmail.com>
To: linux-kernel@vger.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>, Brian Gerst <brgerst@gmail.com>
Subject: [PATCH 0/9] x86-64: Stack protector and percpu improvements
Date: Mon, 23 Oct 2023 17:17:21 -0400 [thread overview]
Message-ID: <20231023211730.40566-1-brgerst@gmail.com> (raw)
Currently, x86-64 uses an unusual per-cpu 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.
P.S.: I posted this series back in 2021, and at the time it appeared that
GCC 8.1 was too recent (released May 2, 2018) to be a requirement to keep
stack protector support. Two years later, support for the new compiler
options should be much more widespread.
Brian Gerst (9):
x86/stackprotector/32: Remove stack protector test script
x86/boot: Disable stack protector for early boot code
x86/stackprotector/64: Convert stack protector to normal percpu
variable
x86/percpu/64: Remove fixed_percpu_data
x86/percpu/64: Use relative percpu offsets
x86/boot/64: Remove inverse relocations
x86/percpu/64: Remove INIT_PER_CPU macros
percpu: Remove PER_CPU_FIRST_SECTION
kallsyms: Remove KALLSYMS_ABSOLUTE_PERCPU
arch/x86/Kconfig | 7 +-
arch/x86/Makefile | 19 +--
arch/x86/boot/compressed/misc.c | 14 +--
arch/x86/entry/entry_64.S | 2 +-
arch/x86/include/asm/percpu.h | 22 ----
arch/x86/include/asm/processor.h | 28 +----
arch/x86/include/asm/stackprotector.h | 37 ++----
arch/x86/kernel/Makefile | 2 +
arch/x86/kernel/asm-offsets_64.c | 6 -
arch/x86/kernel/cpu/common.c | 8 +-
arch/x86/kernel/head_64.S | 10 +-
arch/x86/kernel/irq_64.c | 1 -
arch/x86/kernel/setup_percpu.c | 12 +-
arch/x86/kernel/vmlinux.lds.S | 35 ------
arch/x86/tools/relocs.c | 136 +---------------------
arch/x86/xen/xen-head.S | 6 +-
include/asm-generic/vmlinux.lds.h | 1 -
include/linux/percpu-defs.h | 12 --
init/Kconfig | 11 +-
kernel/kallsyms.c | 12 +-
scripts/gcc-x86_32-has-stack-protector.sh | 8 --
scripts/gcc-x86_64-has-stack-protector.sh | 4 -
scripts/kallsyms.c | 80 +++----------
scripts/link-vmlinux.sh | 4 -
24 files changed, 60 insertions(+), 417 deletions(-)
delete mode 100755 scripts/gcc-x86_32-has-stack-protector.sh
delete mode 100755 scripts/gcc-x86_64-has-stack-protector.sh
--
2.41.0
next reply other threads:[~2023-10-23 21:17 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-23 21:17 Brian Gerst [this message]
2023-10-23 21:17 ` [PATCH 1/9] x86/stackprotector/32: Remove stack protector test script Brian Gerst
2023-10-23 21:17 ` [PATCH 2/9] x86/boot: Disable stack protector for early boot code Brian Gerst
2023-10-23 21:17 ` [PATCH 3/9] x86/stackprotector/64: Convert stack protector to normal percpu variable Brian Gerst
2023-10-24 12:39 ` Uros Bizjak
2023-10-23 21:17 ` [PATCH 4/9] x86/percpu/64: Remove fixed_percpu_data Brian Gerst
2023-10-24 12:33 ` Uros Bizjak
2023-10-24 14:11 ` Brian Gerst
2023-10-23 21:17 ` [PATCH 5/9] x86/percpu/64: Use relative percpu offsets Brian Gerst
2023-10-24 12:43 ` Uros Bizjak
2023-10-23 21:17 ` [PATCH 6/9] x86/boot/64: Remove inverse relocations Brian Gerst
2023-10-23 21:17 ` [PATCH 7/9] x86/percpu/64: Remove INIT_PER_CPU macros Brian Gerst
2023-10-23 21:17 ` [PATCH 8/9] percpu: Remove PER_CPU_FIRST_SECTION Brian Gerst
2023-10-23 21:17 ` [PATCH 9/9] kallsyms: Remove KALLSYMS_ABSOLUTE_PERCPU Brian Gerst
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20231023211730.40566-1-brgerst@gmail.com \
--to=brgerst@gmail.com \
--cc=bp@alien8.de \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=ubizjak@gmail.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox