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

Dennis Zhou
2024-12-10T03:59:14Z

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@linutronix.de>
> Cc: Dennis Zhou <dennis@kernel.org>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Andy Lutomirski <luto@kernel.org>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Nadav Amit <nadav.amit@gmail.com>
> Cc: Brian Gerst <brgerst@gmail.com>
> Cc: Dan Carpenter <dan.carpenter@linaro.org>
> Cc: H. Peter Anvin <hpa@zytor.com>
> Cc: Peter Zijlstra <peterz@infradead.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@kernel.org>

Thanks,
Dennis