From: Michael Ellerman <mpe@ellerman.id.au>
To: Yury Khrustalev <yury.khrustalev@arm.com>,
linux-arch@vger.kernel.org, acme@kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Joey Gouly <joey.gouly@arm.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Sandipan Das <sandipan@linux.ibm.com>,
linuxppc-dev@lists.ozlabs.org, nd@arm.com,
Yury Khrustalev <yury.khrustalev@arm.com>
Subject: Re: [PATCH v3 1/3] mm/pkey: Add PKEY_UNRESTRICTED macro
Date: Wed, 06 Nov 2024 12:00:42 +1100 [thread overview]
Message-ID: <87ttcl89c5.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20241028090715.509527-2-yury.khrustalev@arm.com>
Yury Khrustalev <yury.khrustalev@arm.com> writes:
> Memory protection keys (pkeys) uapi has two macros for pkeys restrictions:
>
> - PKEY_DISABLE_ACCESS 0x1
> - PKEY_DISABLE_WRITE 0x2
>
> with implicit literal value of 0x0 that means "unrestricted". Code that
> works with pkeys has to use this literal value when implying that a pkey
> imposes no restrictions. This may reduce readability because 0 can be
> written in various ways (e.g. 0x0 or 0) and also because 0 in the context
> of pkeys can be mistaken for "no permissions" (akin PROT_NONE) while it
> actually means "no restrictions". This is important because pkeys are
> oftentimes used near mprotect() that uses PROT_ macros.
>
> This patch adds PKEY_UNRESTRICTED macro defined as 0x0.
>
> Signed-off-by: Yury Khrustalev <yury.khrustalev@arm.com>
> ---
> include/uapi/asm-generic/mman-common.h | 1 +
> tools/include/uapi/asm-generic/mman-common.h | 1 +
> 2 files changed, 2 insertions(+)
Apparently you're not meant to modify the copy in tools/, there's a
script that does that, which is run by acme, see:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/include/uapi/README
cheers
next prev parent reply other threads:[~2024-11-06 1:00 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-28 9:07 [PATCH v3 0/3] mm/pkey: Add PKEY_UNRESTRICTED macro Yury Khrustalev
2024-10-28 9:07 ` [PATCH v3 1/3] " Yury Khrustalev
2024-11-06 1:00 ` Michael Ellerman [this message]
2024-11-08 8:59 ` Yury Khrustalev
2024-10-28 9:07 ` [PATCH v3 2/3] selftests/mm: Use " Yury Khrustalev
2024-10-28 9:07 ` [PATCH v3 3/3] selftests/powerpc: " Yury Khrustalev
2024-10-28 9:21 ` Kevin Brodsky
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