linux-kernel - [RFC PATCH 0/3] Enable strict percpu address space checks

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Message-ID: <20240805184012.358023-1-ubizjak@gmail.com>
Date: Mon,  5 Aug 2024 20:38:58 +0200
From: Uros Bizjak <ubizjak@...il.com>
To: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Cc: Uros Bizjak <ubizjak@...il.com>,
	Dennis Zhou <dennis@...nel.org>,
	Tejun Heo <tj@...nel.org>,
	Christoph Lameter <cl@...ux.com>,
	Andy Lutomirski <luto@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Nadav Amit <nadav.amit@...il.com>,
	Brian Gerst <brgerst@...il.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	"H . Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	Luc Van Oostenryck <luc.vanoostenryck@...il.com>
Subject: [RFC PATCH 0/3] Enable strict percpu address space checks 

This patchset enables strict percpu address space checks via x86 named 
address space qualifiers. Percpu variables are declared in
__seg_gs/__seg_fs named AS and kept named AS qualified until they
are dereferenced via percpu accessor. This approach enables various
compiler checks for cross-namespace variable assignments.

Please note that sparse doesn't know anything about __typeof_unqual__()
operator, so the usage of __typeof_unqual__() breaks sparse checking.

Also, the last patch hijacks __percpu tag and repurposes it as a named
address space qualifier. While this works surprisingly well in this RFC
patchset, I would really appreciate some help on how to rewrite this
hack into some "production ready" code.

Cc: Dennis Zhou <dennis@...nel.org>
Cc: Tejun Heo <tj@...nel.org>
Cc: Christoph Lameter <cl@...ux.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Nadav Amit <nadav.amit@...il.com>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Luc Van Oostenryck <luc.vanoostenryck@...il.com>

Uros Bizjak (3):
  percpu: Define __pcpu_typeof()
  percpu: Assorted fixes found by strict percpu address space checks
  percpu/x86: [RFH] Enable strict percpu checks via named AS qualifiers

 arch/x86/include/asm/percpu.h  | 53 ++++++++++++++++++++++++----------
 arch/x86/kernel/head64.c       |  3 +-
 drivers/base/devres.c          |  2 +-
 fs/aio.c                       |  2 +-
 include/linux/cleanup.h        |  4 +--
 include/linux/compiler_types.h |  2 +-
 include/linux/part_stat.h      |  2 +-
 include/linux/percpu-defs.h    | 39 ++++++++++++++++++++-----
 include/linux/prandom.h        |  1 +
 init/Kconfig                   |  3 ++
 kernel/events/hw_breakpoint.c  |  4 +--
 kernel/locking/percpu-rwsem.c  |  2 +-
 kernel/workqueue.c             |  2 +-
 lib/percpu_counter.c           |  2 +-
 net/core/dev.c                 |  2 +-
 15 files changed, 87 insertions(+), 36 deletions(-)

-- 
2.45.2