From: David Hildenbrand <david@redhat.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
linux-arm-kernel@lists.infradead.org
Cc: linux-mm@kvack.org, linux-arch@vger.kernel.org,
Will Deacon <will@kernel.org>,
Dave P Martin <Dave.Martin@arm.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Szabolcs Nagy <szabolcs.nagy@arm.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Andrey Konovalov <andreyknvl@google.com>,
Peter Collingbourne <pcc@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Steven Price <steven.price@arm.com>
Subject: Re: [PATCH v6 06/26] mm: Add PG_arch_2 page flag
Date: Mon, 6 Jul 2020 10:24:04 +0200 [thread overview]
Message-ID: <27fe044a-8315-5394-575e-8f763696b0cd@redhat.com> (raw)
Message-ID: <20200706082404.7mttI-5e00H_hgTDK6iDaLV6pWDYyDN0k_RJKpQeNc0@z> (raw)
In-Reply-To: <20200703153718.16973-7-catalin.marinas@arm.com>
On 03.07.20 17:36, Catalin Marinas wrote:
> From: Steven Price <steven.price@arm.com>
>
> For arm64 MTE support it is necessary to be able to mark pages that
> contain user space visible tags that will need to be saved/restored e.g.
> when swapped out.
>
> To support this add a new arch specific flag (PG_arch_2). This flag is
> only available on 64-bit architectures due to the limited number of
> spare page flags on the 32-bit ones.
>
> Signed-off-by: Steven Price <steven.price@arm.com>
> [catalin.marinas@arm.com: use CONFIG_64BIT for guarding this new flag]
> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> ---
>
> Notes:
> v6:
> - Using CONFIG_64BIT instead of a new CONFIG_ARCH_USES_PG_ARCH_2 option.
>
> New in v4.
>
> fs/proc/page.c | 3 +++
> include/linux/kernel-page-flags.h | 1 +
> include/linux/page-flags.h | 3 +++
> include/trace/events/mmflags.h | 9 ++++++++-
> tools/vm/page-types.c | 2 ++
> 5 files changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/fs/proc/page.c b/fs/proc/page.c
> index f909243d4a66..9f1077d94cde 100644
> --- a/fs/proc/page.c
> +++ b/fs/proc/page.c
> @@ -217,6 +217,9 @@ u64 stable_page_flags(struct page *page)
> u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2);
> u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1);
> u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1);
> +#ifdef CONFIG_64BIT
> + u |= kpf_copy_bit(k, KPF_ARCH_2, PG_arch_2);
> +#endif
>
> return u;
> };
> diff --git a/include/linux/kernel-page-flags.h b/include/linux/kernel-page-flags.h
> index abd20ef93c98..eee1877a354e 100644
> --- a/include/linux/kernel-page-flags.h
> +++ b/include/linux/kernel-page-flags.h
> @@ -17,5 +17,6 @@
> #define KPF_ARCH 38
> #define KPF_UNCACHED 39
> #define KPF_SOFTDIRTY 40
> +#define KPF_ARCH_2 41
>
> #endif /* LINUX_KERNEL_PAGE_FLAGS_H */
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index 6be1aa559b1e..276140c94f4a 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -135,6 +135,9 @@ enum pageflags {
> #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
> PG_young,
> PG_idle,
> +#endif
> +#ifdef CONFIG_64BIT
> + PG_arch_2,
> #endif
> __NR_PAGEFLAGS,
People are usually *very* picky when it comes to new page flags. It
somewhat concerns me that we bump up __NR_PAGEFLAGS for any 64bit arch.
That feels wrong.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2020-07-06 8:24 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-03 15:36 [PATCH v6 00/26] arm64: Memory Tagging Extension user-space support Catalin Marinas
2020-07-03 15:36 ` Catalin Marinas
2020-07-03 15:36 ` [PATCH v6 01/26] arm64: mte: system register definitions Catalin Marinas
2020-07-03 15:36 ` [PATCH v6 02/26] arm64: mte: CPU feature detection and initial sysreg configuration Catalin Marinas
2020-07-13 10:08 ` Steven Price
2020-07-13 17:45 ` Catalin Marinas
2020-07-03 15:36 ` [PATCH v6 03/26] arm64: mte: Use Normal Tagged attributes for the linear map Catalin Marinas
2020-07-03 15:36 ` [PATCH v6 04/26] arm64: mte: Add specific SIGSEGV codes Catalin Marinas
2020-07-03 15:36 ` [PATCH v6 05/26] arm64: mte: Handle synchronous and asynchronous tag check faults Catalin Marinas
2020-07-03 15:36 ` [PATCH v6 06/26] mm: Add PG_arch_2 page flag Catalin Marinas
2020-07-06 8:24 ` David Hildenbrand [this message]
2020-07-06 8:24 ` David Hildenbrand
2020-07-06 11:21 ` Catalin Marinas
2020-07-06 12:42 ` David Hildenbrand
2020-07-06 12:42 ` David Hildenbrand
2020-07-03 15:36 ` [PATCH v6 07/26] mm: Preserve the PG_arch_* flags in __split_huge_page_tail() Catalin Marinas
2020-07-06 14:16 ` David Hildenbrand
2020-07-06 14:16 ` David Hildenbrand
2020-07-06 16:30 ` Catalin Marinas
2020-07-06 17:56 ` David Hildenbrand
2020-07-08 12:17 ` Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 08/26] arm64: mte: Clear the tags when a page is mapped in user-space with PROT_MTE Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 09/26] arm64: mte: Tags-aware copy_{user_,}highpage() implementations Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 10/26] arm64: Avoid unnecessary clear_user_page() indirection Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 11/26] arm64: mte: Tags-aware aware memcmp_pages() implementation Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 12/26] mm: Introduce arch_calc_vm_flag_bits() Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 13/26] arm64: mte: Add PROT_MTE support to mmap() and mprotect() Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 14/26] mm: Introduce arch_validate_flags() Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 15/26] arm64: mte: Validate the PROT_MTE request via arch_validate_flags() Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 16/26] mm: Allow arm64 mmap(PROT_MTE) on RAM-based files Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 17/26] arm64: mte: Allow user control of the tag check mode via prctl() Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 18/26] arm64: mte: Allow user control of the generated random tags " Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 19/26] arm64: mte: Restore the GCR_EL1 register after a suspend Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 20/26] arm64: mte: Add PTRACE_{PEEK,POKE}MTETAGS support Catalin Marinas
2020-07-09 14:41 ` Luis Machado
2020-07-03 15:37 ` [PATCH v6 21/26] fs: Handle intra-page faults in copy_mount_options() Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 22/26] mm: Add arch hooks for saving/restoring tags Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 23/26] arm64: mte: Enable swap of tagged pages Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 24/26] arm64: mte: Save tags when hibernating Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 25/26] arm64: mte: Kconfig entry Catalin Marinas
2020-07-03 15:37 ` [PATCH v6 26/26] arm64: mte: Add Memory Tagging Extension documentation Catalin Marinas
2020-07-09 9:32 ` Szabolcs Nagy
2020-07-09 14:43 ` Catalin Marinas
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