From nobody Fri Nov 29 18:50:01 2024 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id D41E51547E1; Tue, 17 Sep 2024 07:32:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726558341; cv=none; b=Yvy7nblNXZXPL/uzCFCjtghviiDkFGVCamv75q5ajxzEXzSbZTemb2V31K/ImNZSUMdYh0FcQvw/ujSVVvO3gVLi6zNYmIzGcw4C0t+lLK2wyoBeNf7prGZS2hbgucb87sKRGJbqC1ih+sNTf85NUPwDgqDs8nbK/xuNbYV/f3E= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726558341; c=relaxed/simple; bh=C23YUUtESr3bgzB+FarDRqPleSRIGmOGEvTDv35QskE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=l6GnrAkffAIKgsXYcmaB/L7jefQRCiBa/m9FfxYoe1yvxkXl/x45hiclarxvsbgtBU56l7lomw9vQireeIBKO5GEu1qubFyrcbI60Ep3cphpTrWyRHknsBNIMmyRhc79jLCCxYWlfClIqHXtfPuj/+Wxg7RkBYEs36oxK6N1e1Y= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D9BCB1063; Tue, 17 Sep 2024 00:32:47 -0700 (PDT) Received: from a077893.arm.com (unknown [10.163.61.158]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 19E0A3F64C; Tue, 17 Sep 2024 00:32:10 -0700 (PDT) From: Anshuman Khandual To: linux-mm@kvack.org Cc: Anshuman Khandual , Andrew Morton , David Hildenbrand , Ryan Roberts , "Mike Rapoport (IBM)" , Arnd Bergmann , x86@kernel.org, linux-m68k@lists.linux-m68k.org, linux-fsdevel@vger.kernel.org, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Dimitri Sivanich , Alexander Viro , Muchun Song , Andrey Ryabinin , Miaohe Lin , Dennis Zhou , Tejun Heo , Christoph Lameter , Uladzislau Rezki , Christoph Hellwig Subject: [PATCH V2 7/7] mm: Use pgdp_get() for accessing PGD entries Date: Tue, 17 Sep 2024 13:01:17 +0530 Message-Id: <20240917073117.1531207-8-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240917073117.1531207-1-anshuman.khandual@arm.com> References: <20240917073117.1531207-1-anshuman.khandual@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Convert PGD accesses via pgdp_get() helper that defaults as READ_ONCE() but also provides the platform an opportunity to override when required. This stores read page table entry value in a local variable which can be used in multiple instances there after. This helps in avoiding multiple memory load operations as well possible race conditions. Cc: Dimitri Sivanich Cc: Alexander Viro Cc: Muchun Song Cc: Andrey Ryabinin Cc: Miaohe Lin Cc: Dennis Zhou Cc: Tejun Heo cc: Christoph Lameter Cc: Uladzislau Rezki Cc: Christoph Hellwig Cc: linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org Cc: linux-perf-users@vger.kernel.org Cc: kasan-dev@googlegroups.com Signed-off-by: Anshuman Khandual --- drivers/misc/sgi-gru/grufault.c | 2 +- fs/userfaultfd.c | 2 +- include/linux/mm.h | 2 +- include/linux/pgtable.h | 9 ++++++--- kernel/events/core.c | 2 +- mm/gup.c | 11 ++++++----- mm/hugetlb.c | 2 +- mm/kasan/init.c | 8 ++++---- mm/kasan/shadow.c | 2 +- mm/memory-failure.c | 2 +- mm/memory.c | 16 +++++++++------- mm/page_vma_mapped.c | 2 +- mm/percpu.c | 2 +- mm/pgalloc-track.h | 2 +- mm/pgtable-generic.c | 2 +- mm/rmap.c | 2 +- mm/sparse-vmemmap.c | 2 +- mm/vmalloc.c | 13 +++++++------ 18 files changed, 45 insertions(+), 38 deletions(-) diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufaul= t.c index fcaceac60659..6aeccbd440e7 100644 --- a/drivers/misc/sgi-gru/grufault.c +++ b/drivers/misc/sgi-gru/grufault.c @@ -212,7 +212,7 @@ static int atomic_pte_lookup(struct vm_area_struct *vma= , unsigned long vaddr, pte_t pte; =20 pgdp =3D pgd_offset(vma->vm_mm, vaddr); - if (unlikely(pgd_none(*pgdp))) + if (unlikely(pgd_none(pgdp_get(pgdp)))) goto err; =20 p4dp =3D p4d_offset(pgdp, vaddr); diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 4044e15cdfd9..6d33c7a9eb01 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -304,7 +304,7 @@ static inline bool userfaultfd_must_wait(struct userfau= ltfd_ctx *ctx, assert_fault_locked(vmf); =20 pgd =3D pgd_offset(mm, address); - if (!pgd_present(*pgd)) + if (!pgd_present(pgdp_get(pgd))) goto out; p4d =3D p4d_offset(pgd, address); if (!p4d_present(p4dp_get(p4d))) diff --git a/include/linux/mm.h b/include/linux/mm.h index 1bb1599b5779..1978a4b1fcf5 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2819,7 +2819,7 @@ int __pte_alloc_kernel(pmd_t *pmd); static inline p4d_t *p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) { - return (unlikely(pgd_none(*pgd)) && __p4d_alloc(mm, pgd, address)) ? + return (unlikely(pgd_none(pgdp_get(pgd))) && __p4d_alloc(mm, pgd, address= )) ? NULL : p4d_offset(pgd, address); } =20 diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 689cd5a32157..6d12ae7e3982 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -1088,7 +1088,8 @@ static inline int pgd_same(pgd_t pgd_a, pgd_t pgd_b) =20 #define set_pgd_safe(pgdp, pgd) \ ({ \ - WARN_ON_ONCE(pgd_present(*pgdp) && !pgd_same(*pgdp, pgd)); \ + pgd_t __old =3D pgdp_get(pgdp); \ + WARN_ON_ONCE(pgd_present(__old) && !pgd_same(__old, pgd)); \ set_pgd(pgdp, pgd); \ }) =20 @@ -1241,9 +1242,11 @@ void pmd_clear_bad(pmd_t *); =20 static inline int pgd_none_or_clear_bad(pgd_t *pgd) { - if (pgd_none(*pgd)) + pgd_t old_pgd =3D pgdp_get(pgd); + + if (pgd_none(old_pgd)) return 1; - if (unlikely(pgd_bad(*pgd))) { + if (unlikely(pgd_bad(old_pgd))) { pgd_clear_bad(pgd); return 1; } diff --git a/kernel/events/core.c b/kernel/events/core.c index 4e56a276ed25..1e3142211cce 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7603,7 +7603,7 @@ static u64 perf_get_pgtable_size(struct mm_struct *mm= , unsigned long addr) pte_t *ptep, pte; =20 pgdp =3D pgd_offset(mm, addr); - pgd =3D READ_ONCE(*pgdp); + pgd =3D pgdp_get(pgdp); if (pgd_none(pgd)) return 0; =20 diff --git a/mm/gup.c b/mm/gup.c index 3a97d0263052..3aff3555ba19 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1051,7 +1051,7 @@ static struct page *follow_page_mask(struct vm_area_s= truct *vma, unsigned long address, unsigned int flags, struct follow_page_context *ctx) { - pgd_t *pgd; + pgd_t *pgd, old_pgd; struct mm_struct *mm =3D vma->vm_mm; struct page *page; =20 @@ -1060,7 +1060,8 @@ static struct page *follow_page_mask(struct vm_area_s= truct *vma, ctx->page_mask =3D 0; pgd =3D pgd_offset(mm, address); =20 - if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) + old_pgd =3D pgdp_get(pgd); + if (pgd_none(old_pgd) || unlikely(pgd_bad(old_pgd))) page =3D no_page_table(vma, flags, address); else page =3D follow_p4d_mask(vma, address, pgd, flags, ctx); @@ -1111,7 +1112,7 @@ static int get_gate_page(struct mm_struct *mm, unsign= ed long address, pgd =3D pgd_offset_k(address); else pgd =3D pgd_offset_gate(mm, address); - if (pgd_none(*pgd)) + if (pgd_none(pgdp_get(pgd))) return -EFAULT; p4d =3D p4d_offset(pgd, address); if (p4d_none(p4dp_get(p4d))) @@ -3158,7 +3159,7 @@ static int gup_fast_pgd_leaf(pgd_t orig, pgd_t *pgdp,= unsigned long addr, if (!folio) return 0; =20 - if (unlikely(pgd_val(orig) !=3D pgd_val(*pgdp))) { + if (unlikely(pgd_val(orig) !=3D pgd_val(pgdp_get(pgdp)))) { gup_put_folio(folio, refs, flags); return 0; } @@ -3267,7 +3268,7 @@ static void gup_fast_pgd_range(unsigned long addr, un= signed long end, =20 pgdp =3D pgd_offset(current->mm, addr); do { - pgd_t pgd =3D READ_ONCE(*pgdp); + pgd_t pgd =3D pgdp_get(pgdp); =20 next =3D pgd_addr_end(addr, end); if (pgd_none(pgd)) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 4fdb91c8cc2b..294d74b03d83 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -7451,7 +7451,7 @@ pte_t *huge_pte_offset(struct mm_struct *mm, pmd_t *pmd; =20 pgd =3D pgd_offset(mm, addr); - if (!pgd_present(*pgd)) + if (!pgd_present(pgdp_get(pgd))) return NULL; p4d =3D p4d_offset(pgd, addr); if (!p4d_present(p4dp_get(p4d))) diff --git a/mm/kasan/init.c b/mm/kasan/init.c index 02af738fee5e..c2b307716551 100644 --- a/mm/kasan/init.c +++ b/mm/kasan/init.c @@ -271,7 +271,7 @@ int __ref kasan_populate_early_shadow(const void *shado= w_start, continue; } =20 - if (pgd_none(*pgd)) { + if (pgd_none(pgdp_get(pgd))) { p4d_t *p; =20 if (slab_is_available()) { @@ -345,7 +345,7 @@ static void kasan_free_p4d(p4d_t *p4d_start, pgd_t *pgd) return; } =20 - p4d_free(&init_mm, (p4d_t *)page_to_virt(pgd_page(*pgd))); + p4d_free(&init_mm, (p4d_t *)page_to_virt(pgd_page(pgdp_get(pgd)))); pgd_clear(pgd); } =20 @@ -468,10 +468,10 @@ void kasan_remove_zero_shadow(void *start, unsigned l= ong size) next =3D pgd_addr_end(addr, end); =20 pgd =3D pgd_offset_k(addr); - if (!pgd_present(*pgd)) + if (!pgd_present(pgdp_get(pgd))) continue; =20 - if (kasan_p4d_table(*pgd)) { + if (kasan_p4d_table(pgdp_get(pgd))) { if (IS_ALIGNED(addr, PGDIR_SIZE) && IS_ALIGNED(next, PGDIR_SIZE)) { pgd_clear(pgd); diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c index 52150cc5ae5f..7f3c46237816 100644 --- a/mm/kasan/shadow.c +++ b/mm/kasan/shadow.c @@ -191,7 +191,7 @@ static bool shadow_mapped(unsigned long addr) pmd_t *pmd; pte_t *pte; =20 - if (pgd_none(*pgd)) + if (pgd_none(pgdp_get(pgd))) return false; p4d =3D p4d_offset(pgd, addr); if (p4d_none(p4dp_get(p4d))) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 3d900cc039b3..c9397eab52bd 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -411,7 +411,7 @@ static unsigned long dev_pagemap_mapping_shift(struct v= m_area_struct *vma, =20 VM_BUG_ON_VMA(address =3D=3D -EFAULT, vma); pgd =3D pgd_offset(vma->vm_mm, address); - if (!pgd_present(*pgd)) + if (!pgd_present(pgdp_get(pgd))) return 0; p4d =3D p4d_offset(pgd, address); if (!p4d_present(p4dp_get(p4d))) diff --git a/mm/memory.c b/mm/memory.c index 5056f39f2c3b..b4845a84ceb5 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2942,7 +2942,7 @@ static int __apply_to_page_range(struct mm_struct *mm= , unsigned long addr, unsigned long size, pte_fn_t fn, void *data, bool create) { - pgd_t *pgd; + pgd_t *pgd, old_pgd; unsigned long start =3D addr, next; unsigned long end =3D addr + size; pgtbl_mod_mask mask =3D 0; @@ -2954,11 +2954,12 @@ static int __apply_to_page_range(struct mm_struct *= mm, unsigned long addr, pgd =3D pgd_offset(mm, addr); do { next =3D pgd_addr_end(addr, end); - if (pgd_none(*pgd) && !create) + old_pgd =3D pgdp_get(pgd); + if (pgd_none(old_pgd) && !create) continue; - if (WARN_ON_ONCE(pgd_leaf(*pgd))) + if (WARN_ON_ONCE(pgd_leaf(old_pgd))) return -EINVAL; - if (!pgd_none(*pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) { + if (!pgd_none(old_pgd) && WARN_ON_ONCE(pgd_bad(old_pgd))) { if (!create) continue; pgd_clear_bad(pgd); @@ -6053,7 +6054,7 @@ int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, uns= igned long address) return -ENOMEM; =20 spin_lock(&mm->page_table_lock); - if (pgd_present(*pgd)) { /* Another has populated it */ + if (pgd_present(pgdp_get(pgd))) { /* Another has populated it */ p4d_free(mm, new); } else { smp_wmb(); /* See comment in pmd_install() */ @@ -6143,7 +6144,7 @@ int follow_pte(struct vm_area_struct *vma, unsigned l= ong address, pte_t **ptepp, spinlock_t **ptlp) { struct mm_struct *mm =3D vma->vm_mm; - pgd_t *pgd; + pgd_t *pgd, old_pgd; p4d_t *p4d, old_p4d; pud_t *pud; pmd_t *pmd; @@ -6157,7 +6158,8 @@ int follow_pte(struct vm_area_struct *vma, unsigned l= ong address, goto out; =20 pgd =3D pgd_offset(mm, address); - if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) + old_pgd =3D pgdp_get(pgd); + if (pgd_none(old_pgd) || unlikely(pgd_bad(old_pgd))) goto out; =20 p4d =3D p4d_offset(pgd, address); diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index a33f92db2666..fb8b610f7378 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -212,7 +212,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *= pvmw) restart: do { pgd =3D pgd_offset(mm, pvmw->address); - if (!pgd_present(*pgd)) { + if (!pgd_present(pgdp_get(pgd))) { step_forward(pvmw, PGDIR_SIZE); continue; } diff --git a/mm/percpu.c b/mm/percpu.c index 58660e8eb892..70e68ab002e9 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -3184,7 +3184,7 @@ void __init __weak pcpu_populate_pte(unsigned long ad= dr) pud_t *pud; pmd_t *pmd; =20 - if (pgd_none(*pgd)) { + if (pgd_none(pgdp_get(pgd))) { p4d =3D memblock_alloc(P4D_TABLE_SIZE, P4D_TABLE_SIZE); if (!p4d) goto err_alloc; diff --git a/mm/pgalloc-track.h b/mm/pgalloc-track.h index 3db8ccbcb141..644f632c7cba 100644 --- a/mm/pgalloc-track.h +++ b/mm/pgalloc-track.h @@ -7,7 +7,7 @@ static inline p4d_t *p4d_alloc_track(struct mm_struct *mm, = pgd_t *pgd, unsigned long address, pgtbl_mod_mask *mod_mask) { - if (unlikely(pgd_none(*pgd))) { + if (unlikely(pgd_none(pgdp_get(pgd)))) { if (__p4d_alloc(mm, pgd, address)) return NULL; *mod_mask |=3D PGTBL_PGD_MODIFIED; diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c index f5ab52beb536..16c1ed5b3d0b 100644 --- a/mm/pgtable-generic.c +++ b/mm/pgtable-generic.c @@ -24,7 +24,7 @@ =20 void pgd_clear_bad(pgd_t *pgd) { - pgd_ERROR(*pgd); + pgd_ERROR(pgdp_get(pgd)); pgd_clear(pgd); } =20 diff --git a/mm/rmap.c b/mm/rmap.c index a0ff325467eb..5f4c52f34192 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -809,7 +809,7 @@ pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long = address) pmd_t *pmd =3D NULL; =20 pgd =3D pgd_offset(mm, address); - if (!pgd_present(*pgd)) + if (!pgd_present(pgdp_get(pgd))) goto out; =20 p4d =3D p4d_offset(pgd, address); diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c index 2bd1c95f107a..ffc78329a130 100644 --- a/mm/sparse-vmemmap.c +++ b/mm/sparse-vmemmap.c @@ -233,7 +233,7 @@ p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsi= gned long addr, int node) pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node) { pgd_t *pgd =3D pgd_offset_k(addr); - if (pgd_none(*pgd)) { + if (pgd_none(pgdp_get(pgd))) { void *p =3D vmemmap_alloc_block_zero(PAGE_SIZE, node); if (!p) return NULL; diff --git a/mm/vmalloc.c b/mm/vmalloc.c index f27ecac7bd6e..a40323a8c6ab 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -450,7 +450,7 @@ void __vunmap_range_noflush(unsigned long start, unsign= ed long end) pgd =3D pgd_offset_k(addr); do { next =3D pgd_addr_end(addr, end); - if (pgd_bad(*pgd)) + if (pgd_bad(pgdp_get(pgd))) mask |=3D PGTBL_PGD_MODIFIED; if (pgd_none_or_clear_bad(pgd)) continue; @@ -582,7 +582,7 @@ static int vmap_small_pages_range_noflush(unsigned long= addr, unsigned long end, pgd =3D pgd_offset_k(addr); do { next =3D pgd_addr_end(addr, end); - if (pgd_bad(*pgd)) + if (pgd_bad(pgdp_get(pgd))) mask |=3D PGTBL_PGD_MODIFIED; err =3D vmap_pages_p4d_range(pgd, addr, next, prot, pages, &nr, &mask); if (err) @@ -740,7 +740,7 @@ struct page *vmalloc_to_page(const void *vmalloc_addr) { unsigned long addr =3D (unsigned long) vmalloc_addr; struct page *page =3D NULL; - pgd_t *pgd =3D pgd_offset_k(addr); + pgd_t *pgd =3D pgd_offset_k(addr), old_pgd; p4d_t *p4d, old_p4d; pud_t *pud, old_pud; pmd_t *pmd, old_pmd; @@ -752,11 +752,12 @@ struct page *vmalloc_to_page(const void *vmalloc_addr) */ VIRTUAL_BUG_ON(!is_vmalloc_or_module_addr(vmalloc_addr)); =20 - if (pgd_none(*pgd)) + old_pgd =3D pgdp_get(pgd); + if (pgd_none(old_pgd)) return NULL; - if (WARN_ON_ONCE(pgd_leaf(*pgd))) + if (WARN_ON_ONCE(pgd_leaf(old_pgd))) return NULL; /* XXX: no allowance for huge pgd */ - if (WARN_ON_ONCE(pgd_bad(*pgd))) + if (WARN_ON_ONCE(pgd_bad(old_pgd))) return NULL; =20 p4d =3D p4d_offset(pgd, addr); --=20 2.25.1