linux-kernel - Re: [PATCH v3 0/6] Enable strict percpu address space checks

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Message-ID: <Z1e8jtHt93l0ONu1@V92F7Y9K0C>
Date: Mon, 9 Dec 2024 19:59:10 -0800
From: Dennis Zhou <dennis@...nel.org>
To: Uros Bizjak <ubizjak@...il.com>
Cc: x86@...nel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linux-bcachefs@...r.kernel.org, linux-arch@...r.kernel.org,
	netdev@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Tejun Heo <tj@...nel.org>, Christoph Lameter <cl@...ux.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>, Ingo Molnar <mingo@...nel.org>,
	Nadav Amit <nadav.amit@...il.com>, Brian Gerst <brgerst@...il.com>,
	Dan Carpenter <dan.carpenter@...aro.org>,
	"H . Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v3 0/6] Enable strict percpu address space checks

Hi Uros,

On Sun, Dec 08, 2024 at 09:45:15PM +0100, Uros Bizjak wrote:
> Enable 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 current version of sparse doesn't know anything about
> __typeof_unqual__() operator. Avoid the usage of __typeof_unqual__()
> when sparse checking is active to prevent sparse errors with unknowing
> keyword. The proposed patch by Dan Carpenter to implement
> __typeof_unqual__() handling in sparse is located at:
> 
> https://lore.kernel.org/lkml/5b8d0dee-8fb6-45af-ba6c-7f74aff9a4b8@stanley.mountain/
> 
> v2: - Add comment to remove test for __CHECKER__ once sparse learns
>       about __typeof_unqual__.
>     - Add Acked-by: tags.
> v3: - Rename __per_cpu_qual to __percpu_qual.
>     - Add more Acked-by: tags.
> 
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Dennis Zhou <dennis@...nel.org>
> Cc: Tejun Heo <tj@...nel.org>
> Cc: Christoph Lameter <cl@...ux.com>
> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> 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: Dan Carpenter <dan.carpenter@...aro.org>
> Cc: H. Peter Anvin <hpa@...or.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> 
> Uros Bizjak (6):
>   x86/kgdb: Use IS_ERR_PCPU() macro
>   compiler.h: Introduce TYPEOF_UNQUAL() macro
>   percpu: Use TYPEOF_UNQUAL() in variable declarations
>   percpu: Use TYPEOF_UNQUAL() in *_cpu_ptr() accessors
>   percpu: Repurpose __percpu tag as a named address space qualifier
>   percpu/x86: Enable strict percpu checks via named AS qualifiers
> 
>  arch/x86/include/asm/percpu.h  | 38 ++++++++++++++++++++++++---------
>  arch/x86/kernel/kgdb.c         |  2 +-
>  fs/bcachefs/util.h             |  2 +-
>  include/asm-generic/percpu.h   | 39 ++++++++++++++++++++++------------
>  include/linux/compiler.h       | 13 ++++++++++++
>  include/linux/compiler_types.h |  2 +-
>  include/linux/part_stat.h      |  2 +-
>  include/linux/percpu-defs.h    |  6 +++---
>  include/net/snmp.h             |  5 ++---
>  init/Kconfig                   |  3 +++
>  kernel/locking/percpu-rwsem.c  |  2 +-
>  net/mpls/internal.h            |  4 ++--
>  12 files changed, 82 insertions(+), 36 deletions(-)
> 
> -- 
> 2.42.0
> 

This all looks good to me.

Acked-by: Dennis Zhou <dennis@...nel.org>

Thanks,
Dennis