From: Steven Price <steven.price@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
linux-arch@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Arnd Bergmann <arnd@arndb.de>, Hugh Dickins <hughd@google.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Will Deacon <will@kernel.org>
Subject: Re: [PATCH 3/4] arm64: mte: Enable swap of tagged pages
Date: Mon, 4 May 2020 13:53:23 +0100 [thread overview]
Message-ID: <2ef10bcf-e019-beaf-10fb-b342f96e188c@arm.com> (raw)
In-Reply-To: <20200503152858.GA11959@gaia>
On 03/05/2020 16:29, Catalin Marinas wrote:
> On Wed, Apr 22, 2020 at 03:25:29PM +0100, Steven Price wrote:
>> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
>> index 39a372bf8afc..a4ad1b75a1a7 100644
>> --- a/arch/arm64/include/asm/pgtable.h
>> +++ b/arch/arm64/include/asm/pgtable.h
>> @@ -80,6 +80,8 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
>> #define pte_user_exec(pte) (!(pte_val(pte) & PTE_UXN))
>> #define pte_cont(pte) (!!(pte_val(pte) & PTE_CONT))
>> #define pte_devmap(pte) (!!(pte_val(pte) & PTE_DEVMAP))
>> +#define pte_tagged(pte) (!!((pte_val(pte) & PTE_ATTRINDX_MASK) == \
>> + PTE_ATTRINDX(MT_NORMAL_TAGGED)))
>>
>> #define pte_cont_addr_end(addr, end) \
>> ({ unsigned long __boundary = ((addr) + CONT_PTE_SIZE) & CONT_PTE_MASK; \
>> @@ -268,12 +270,17 @@ static inline void __check_racy_pte_update(struct mm_struct *mm, pte_t *ptep,
>> __func__, pte_val(old_pte), pte_val(pte));
>> }
>>
>> +void mte_sync_tags(pte_t *ptep, pte_t pte);
>> +
>> static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
>> pte_t *ptep, pte_t pte)
>> {
>> if (pte_present(pte) && pte_user_exec(pte) && !pte_special(pte))
>> __sync_icache_dcache(pte);
>>
>> + if (system_supports_mte() && pte_tagged(pte))
>> + mte_sync_tags(ptep, pte);
>
> I think this needs a pte_present() check as well, otherwise pte_tagged()
> could match some random swap entry.
Good spot - mte_sync_tags() bails out fairly early in this case (which
explains why I didn't see any problems). But it's *after* PG_mte_tagged
is set which will lead to incorrectly flagging pages.
Thanks,
Steve
next prev parent reply other threads:[~2020-05-04 12:53 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-22 14:25 [PATCH 0/4] arm64: MTE swap and hibernation support Steven Price
2020-04-22 14:25 ` [PATCH 1/4] mm: Add PG_ARCH_2 page flag Steven Price
2020-04-22 14:25 ` [PATCH 2/4] mm: Add arch hooks for saving/restoring tags Steven Price
2020-04-22 18:08 ` Dave Hansen
2020-04-23 9:09 ` Catalin Marinas
2020-04-23 12:37 ` Steven Price
2020-04-22 14:25 ` [PATCH 3/4] arm64: mte: Enable swap of tagged pages Steven Price
2020-04-22 18:34 ` Dave Hansen
2020-04-23 13:51 ` Steven Price
2020-05-03 15:29 ` Catalin Marinas
2020-05-04 12:53 ` Steven Price [this message]
2020-04-22 14:25 ` [PATCH 4/4] arm64: mte: Save tags when hibernating Steven Price
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