From: Peter Collingbourne <pcc@google.com> To: Catalin Marinas <catalin.marinas@arm.com> Cc: "Peter Collingbourne" <pcc@google.com>, "Qun-wei Lin (林群崴)" <Qun-wei.Lin@mediatek.com>, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "surenb@google.com" <surenb@google.com>, "david@redhat.com" <david@redhat.com>, "Chinwen Chang (張錦文)" <chinwen.chang@mediatek.com>, "kasan-dev@googlegroups.com" <kasan-dev@googlegroups.com>, "Kuan-Ying Lee (李冠穎)" <Kuan-Ying.Lee@mediatek.com>, "Casper Li (李中榮)" <casper.li@mediatek.com>, "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>, vincenzo.frascino@arm.com, "Alexandru Elisei" <alexandru.elisei@arm.com>, will@kernel.org, eugenis@google.com, "Steven Price" <steven.price@arm.com> Subject: [PATCH v4 3/3] arm64: mte: Simplify swap tag restoration logic Date: Mon, 22 May 2023 17:43:10 -0700 [thread overview] Message-ID: <20230523004312.1807357-4-pcc@google.com> (raw) In-Reply-To: <20230523004312.1807357-1-pcc@google.com> As a result of the previous two patches, there are no circumstances in which a swapped-in page is installed in a page table without first having arch_swap_restore() called on it. Therefore, we no longer need the logic in set_pte_at() that restores the tags, so remove it. Signed-off-by: Peter Collingbourne <pcc@google.com> Link: https://linux-review.googlesource.com/id/I8ad54476f3b2d0144ccd8ce0c1d7a2963e5ff6f3 Reviewed-by: Steven Price <steven.price@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> --- v4: - Rebased onto v6.4-rc3 - Reverted change to arch/arm64/mm/mteswap.c; this change was not valid because swapcache pages can have arch_swap_restore() called on them multiple times v3: - Rebased onto arm64/for-next/fixes, which already has a fix for the issue previously tagged, therefore removed Fixes: tag arch/arm64/include/asm/mte.h | 4 ++-- arch/arm64/include/asm/pgtable.h | 14 ++---------- arch/arm64/kernel/mte.c | 37 ++++++-------------------------- 3 files changed, 11 insertions(+), 44 deletions(-) diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h index c028afb1cd0b..4cedbaa16f41 100644 --- a/arch/arm64/include/asm/mte.h +++ b/arch/arm64/include/asm/mte.h @@ -90,7 +90,7 @@ static inline bool try_page_mte_tagging(struct page *page) } void mte_zero_clear_page_tags(void *addr); -void mte_sync_tags(pte_t old_pte, pte_t pte); +void mte_sync_tags(pte_t pte); void mte_copy_page_tags(void *kto, const void *kfrom); void mte_thread_init_user(void); void mte_thread_switch(struct task_struct *next); @@ -122,7 +122,7 @@ static inline bool try_page_mte_tagging(struct page *page) static inline void mte_zero_clear_page_tags(void *addr) { } -static inline void mte_sync_tags(pte_t old_pte, pte_t pte) +static inline void mte_sync_tags(pte_t pte) { } static inline void mte_copy_page_tags(void *kto, const void *kfrom) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 0bd18de9fd97..e8a252e62b12 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -337,18 +337,8 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr, * don't expose tags (instruction fetches don't check tags). */ if (system_supports_mte() && pte_access_permitted(pte, false) && - !pte_special(pte)) { - pte_t old_pte = READ_ONCE(*ptep); - /* - * We only need to synchronise if the new PTE has tags enabled - * or if swapping in (in which case another mapping may have - * set tags in the past even if this PTE isn't tagged). - * (!pte_none() && !pte_present()) is an open coded version of - * is_swap_pte() - */ - if (pte_tagged(pte) || (!pte_none(old_pte) && !pte_present(old_pte))) - mte_sync_tags(old_pte, pte); - } + !pte_special(pte) && pte_tagged(pte)) + mte_sync_tags(pte); __check_safe_pte_update(mm, ptep, pte); diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index 7e89968bd282..c40728046fed 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -35,41 +35,18 @@ DEFINE_STATIC_KEY_FALSE(mte_async_or_asymm_mode); EXPORT_SYMBOL_GPL(mte_async_or_asymm_mode); #endif -static void mte_sync_page_tags(struct page *page, pte_t old_pte, - bool check_swap, bool pte_is_tagged) -{ - if (check_swap && is_swap_pte(old_pte)) { - swp_entry_t entry = pte_to_swp_entry(old_pte); - - if (!non_swap_entry(entry)) - mte_restore_tags(entry, page); - } - - if (!pte_is_tagged) - return; - - if (try_page_mte_tagging(page)) { - mte_clear_page_tags(page_address(page)); - set_page_mte_tagged(page); - } -} - -void mte_sync_tags(pte_t old_pte, pte_t pte) +void mte_sync_tags(pte_t pte) { struct page *page = pte_page(pte); long i, nr_pages = compound_nr(page); - bool check_swap = nr_pages == 1; - bool pte_is_tagged = pte_tagged(pte); - - /* Early out if there's nothing to do */ - if (!check_swap && !pte_is_tagged) - return; /* if PG_mte_tagged is set, tags have already been initialised */ - for (i = 0; i < nr_pages; i++, page++) - if (!page_mte_tagged(page)) - mte_sync_page_tags(page, old_pte, check_swap, - pte_is_tagged); + for (i = 0; i < nr_pages; i++, page++) { + if (try_page_mte_tagging(page)) { + mte_clear_page_tags(page_address(page)); + set_page_mte_tagged(page); + } + } /* ensure the tags are visible before the PTE is set */ smp_wmb(); -- 2.40.1.698.g37aff9b760-goog
WARNING: multiple messages have this Message-ID (diff)
From: Peter Collingbourne <pcc@google.com> To: Catalin Marinas <catalin.marinas@arm.com> Cc: "Peter Collingbourne" <pcc@google.com>, "Qun-wei Lin (林群崴)" <Qun-wei.Lin@mediatek.com>, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "surenb@google.com" <surenb@google.com>, "david@redhat.com" <david@redhat.com>, "Chinwen Chang (張錦文)" <chinwen.chang@mediatek.com>, "kasan-dev@googlegroups.com" <kasan-dev@googlegroups.com>, "Kuan-Ying Lee (李冠穎)" <Kuan-Ying.Lee@mediatek.com>, "Casper Li (李中榮)" <casper.li@mediatek.com>, "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>, vincenzo.frascino@arm.com, "Alexandru Elisei" <alexandru.elisei@arm.com>, will@kernel.org, eugenis@google.com, "Steven Price" <steven.price@arm.com> Subject: [PATCH v4 3/3] arm64: mte: Simplify swap tag restoration logic Date: Mon, 22 May 2023 17:43:10 -0700 [thread overview] Message-ID: <20230523004312.1807357-4-pcc@google.com> (raw) In-Reply-To: <20230523004312.1807357-1-pcc@google.com> As a result of the previous two patches, there are no circumstances in which a swapped-in page is installed in a page table without first having arch_swap_restore() called on it. Therefore, we no longer need the logic in set_pte_at() that restores the tags, so remove it. Signed-off-by: Peter Collingbourne <pcc@google.com> Link: https://linux-review.googlesource.com/id/I8ad54476f3b2d0144ccd8ce0c1d7a2963e5ff6f3 Reviewed-by: Steven Price <steven.price@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> --- v4: - Rebased onto v6.4-rc3 - Reverted change to arch/arm64/mm/mteswap.c; this change was not valid because swapcache pages can have arch_swap_restore() called on them multiple times v3: - Rebased onto arm64/for-next/fixes, which already has a fix for the issue previously tagged, therefore removed Fixes: tag arch/arm64/include/asm/mte.h | 4 ++-- arch/arm64/include/asm/pgtable.h | 14 ++---------- arch/arm64/kernel/mte.c | 37 ++++++-------------------------- 3 files changed, 11 insertions(+), 44 deletions(-) diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h index c028afb1cd0b..4cedbaa16f41 100644 --- a/arch/arm64/include/asm/mte.h +++ b/arch/arm64/include/asm/mte.h @@ -90,7 +90,7 @@ static inline bool try_page_mte_tagging(struct page *page) } void mte_zero_clear_page_tags(void *addr); -void mte_sync_tags(pte_t old_pte, pte_t pte); +void mte_sync_tags(pte_t pte); void mte_copy_page_tags(void *kto, const void *kfrom); void mte_thread_init_user(void); void mte_thread_switch(struct task_struct *next); @@ -122,7 +122,7 @@ static inline bool try_page_mte_tagging(struct page *page) static inline void mte_zero_clear_page_tags(void *addr) { } -static inline void mte_sync_tags(pte_t old_pte, pte_t pte) +static inline void mte_sync_tags(pte_t pte) { } static inline void mte_copy_page_tags(void *kto, const void *kfrom) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 0bd18de9fd97..e8a252e62b12 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -337,18 +337,8 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr, * don't expose tags (instruction fetches don't check tags). */ if (system_supports_mte() && pte_access_permitted(pte, false) && - !pte_special(pte)) { - pte_t old_pte = READ_ONCE(*ptep); - /* - * We only need to synchronise if the new PTE has tags enabled - * or if swapping in (in which case another mapping may have - * set tags in the past even if this PTE isn't tagged). - * (!pte_none() && !pte_present()) is an open coded version of - * is_swap_pte() - */ - if (pte_tagged(pte) || (!pte_none(old_pte) && !pte_present(old_pte))) - mte_sync_tags(old_pte, pte); - } + !pte_special(pte) && pte_tagged(pte)) + mte_sync_tags(pte); __check_safe_pte_update(mm, ptep, pte); diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index 7e89968bd282..c40728046fed 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -35,41 +35,18 @@ DEFINE_STATIC_KEY_FALSE(mte_async_or_asymm_mode); EXPORT_SYMBOL_GPL(mte_async_or_asymm_mode); #endif -static void mte_sync_page_tags(struct page *page, pte_t old_pte, - bool check_swap, bool pte_is_tagged) -{ - if (check_swap && is_swap_pte(old_pte)) { - swp_entry_t entry = pte_to_swp_entry(old_pte); - - if (!non_swap_entry(entry)) - mte_restore_tags(entry, page); - } - - if (!pte_is_tagged) - return; - - if (try_page_mte_tagging(page)) { - mte_clear_page_tags(page_address(page)); - set_page_mte_tagged(page); - } -} - -void mte_sync_tags(pte_t old_pte, pte_t pte) +void mte_sync_tags(pte_t pte) { struct page *page = pte_page(pte); long i, nr_pages = compound_nr(page); - bool check_swap = nr_pages == 1; - bool pte_is_tagged = pte_tagged(pte); - - /* Early out if there's nothing to do */ - if (!check_swap && !pte_is_tagged) - return; /* if PG_mte_tagged is set, tags have already been initialised */ - for (i = 0; i < nr_pages; i++, page++) - if (!page_mte_tagged(page)) - mte_sync_page_tags(page, old_pte, check_swap, - pte_is_tagged); + for (i = 0; i < nr_pages; i++, page++) { + if (try_page_mte_tagging(page)) { + mte_clear_page_tags(page_address(page)); + set_page_mte_tagged(page); + } + } /* ensure the tags are visible before the PTE is set */ smp_wmb(); -- 2.40.1.698.g37aff9b760-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-05-23 0:52 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-05-23 0:43 [PATCH v4 0/3] mm: Fix bug affecting swapping in MTE tagged pages Peter Collingbourne 2023-05-23 0:43 ` Peter Collingbourne 2023-05-23 0:43 ` [PATCH v4 1/3] mm: Call arch_swap_restore() from do_swap_page() Peter Collingbourne 2023-05-23 0:43 ` Peter Collingbourne 2023-06-05 14:05 ` Will Deacon 2023-06-05 14:05 ` Will Deacon 2023-06-05 17:41 ` Peter Collingbourne 2023-06-05 17:41 ` Peter Collingbourne 2023-06-29 9:57 ` Catalin Marinas 2023-06-29 9:57 ` Catalin Marinas 2023-07-02 19:38 ` Andrew Morton 2023-07-02 19:38 ` Andrew Morton 2023-07-03 15:05 ` Catalin Marinas 2023-07-03 15:05 ` Catalin Marinas 2023-05-23 0:43 ` [PATCH v4 2/3] mm: Call arch_swap_restore() from unuse_pte() Peter Collingbourne 2023-05-23 0:43 ` Peter Collingbourne 2023-05-23 0:43 ` Peter Collingbourne [this message] 2023-05-23 0:43 ` [PATCH v4 3/3] arm64: mte: Simplify swap tag restoration logic Peter Collingbourne
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