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Wed, 18 Dec 2024 05:06:04 -0800 (PST) From: Qi Zheng To: peterz@infradead.org, tglx@linutronix.de, david@redhat.com, jannh@google.com, hughd@google.com, yuzhao@google.com, willy@infradead.org, muchun.song@linux.dev, vbabka@kernel.org, lorenzo.stoakes@oracle.com, akpm@linux-foundation.org, rientjes@google.com, vishal.moola@gmail.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Qi Zheng , linux-riscv@lists.infradead.org Subject: [PATCH v2 08/15] riscv: pgtable: move pagetable_dtor() to __tlb_remove_table() Date: Wed, 18 Dec 2024 21:04:44 +0800 Message-Id: X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: References: 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" Move pagetable_dtor() to __tlb_remove_table(), so that ptlock and page table pages can be freed together (regardless of whether RCU is used). This prevents the use-after-free problem where the ptlock is freed immediately but the page table pages is freed later via RCU. Page tables shouldn't have swap cache, so use pagetable_free() instead of free_page_and_swap_cache() to free page table pages. By the way, move the comment above __tlb_remove_table() to riscv_tlb_remove_ptdesc(), it will be more appropriate. Signed-off-by: Qi Zheng Suggested-by: Peter Zijlstra (Intel) Cc: linux-riscv@lists.infradead.org --- arch/riscv/include/asm/pgalloc.h | 38 ++++++++++++++------------------ arch/riscv/include/asm/tlb.h | 14 ++++-------- 2 files changed, 21 insertions(+), 31 deletions(-) diff --git a/arch/riscv/include/asm/pgalloc.h b/arch/riscv/include/asm/pgal= loc.h index 09c2eff571a49..fc50d14010246 100644 --- a/arch/riscv/include/asm/pgalloc.h +++ b/arch/riscv/include/asm/pgalloc.h @@ -18,12 +18,22 @@ #define __HAVE_ARCH_P4D_FREE #include =20 +/* + * While riscv platforms with riscv_ipi_for_rfence as true require an IPI = to + * perform TLB shootdown, some platforms with riscv_ipi_for_rfence as fals= e use + * SBI to perform TLB shootdown. To keep software pagetable walkers safe i= n this + * case we switch to RCU based table free (MMU_GATHER_RCU_TABLE_FREE). See= the + * comment below 'ifdef CONFIG_MMU_GATHER_RCU_TABLE_FREE' in include/asm-g= eneric/tlb.h + * for more details. + */ static inline void riscv_tlb_remove_ptdesc(struct mmu_gather *tlb, void *p= t) { - if (riscv_use_sbi_for_rfence()) + if (riscv_use_sbi_for_rfence()) { tlb_remove_ptdesc(tlb, pt); - else + } else { + pagetable_dtor(pt); tlb_remove_page_ptdesc(tlb, pt); + } } =20 static inline void pmd_populate_kernel(struct mm_struct *mm, @@ -109,12 +119,8 @@ static inline void pud_free(struct mm_struct *mm, pud_= t *pud) static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pud, unsigned long addr) { - if (pgtable_l4_enabled) { - struct ptdesc *ptdesc =3D virt_to_ptdesc(pud); - - pagetable_dtor(ptdesc); - riscv_tlb_remove_ptdesc(tlb, ptdesc); - } + if (pgtable_l4_enabled) + riscv_tlb_remove_ptdesc(tlb, virt_to_ptdesc(pud)); } =20 #define p4d_alloc_one p4d_alloc_one @@ -136,12 +142,8 @@ static inline void p4d_free(struct mm_struct *mm, p4d_= t *p4d) static inline void __p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d, unsigned long addr) { - if (pgtable_l5_enabled) { - struct ptdesc *ptdesc =3D virt_to_ptdesc(p4d); - - pagetable_dtor(ptdesc); + if (pgtable_l5_enabled) riscv_tlb_remove_ptdesc(tlb, virt_to_ptdesc(p4d)); - } } #endif /* __PAGETABLE_PMD_FOLDED */ =20 @@ -170,10 +172,7 @@ static inline pgd_t *pgd_alloc(struct mm_struct *mm) static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd, unsigned long addr) { - struct ptdesc *ptdesc =3D virt_to_ptdesc(pmd); - - pagetable_dtor(ptdesc); - riscv_tlb_remove_ptdesc(tlb, ptdesc); + riscv_tlb_remove_ptdesc(tlb, virt_to_ptdesc(pmd)); } =20 #endif /* __PAGETABLE_PMD_FOLDED */ @@ -181,10 +180,7 @@ static inline void __pmd_free_tlb(struct mmu_gather *t= lb, pmd_t *pmd, static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte, unsigned long addr) { - struct ptdesc *ptdesc =3D page_ptdesc(pte); - - pagetable_dtor(ptdesc); - riscv_tlb_remove_ptdesc(tlb, ptdesc); + riscv_tlb_remove_ptdesc(tlb, page_ptdesc(pte)); } #endif /* CONFIG_MMU */ =20 diff --git a/arch/riscv/include/asm/tlb.h b/arch/riscv/include/asm/tlb.h index 1f6c38420d8e0..ded8724b3c4f7 100644 --- a/arch/riscv/include/asm/tlb.h +++ b/arch/riscv/include/asm/tlb.h @@ -11,19 +11,13 @@ struct mmu_gather; static void tlb_flush(struct mmu_gather *tlb); =20 #ifdef CONFIG_MMU -#include =20 -/* - * While riscv platforms with riscv_ipi_for_rfence as true require an IPI = to - * perform TLB shootdown, some platforms with riscv_ipi_for_rfence as fals= e use - * SBI to perform TLB shootdown. To keep software pagetable walkers safe i= n this - * case we switch to RCU based table free (MMU_GATHER_RCU_TABLE_FREE). See= the - * comment below 'ifdef CONFIG_MMU_GATHER_RCU_TABLE_FREE' in include/asm-g= eneric/tlb.h - * for more details. - */ static inline void __tlb_remove_table(void *table) { - free_page_and_swap_cache(table); + struct ptdesc *ptdesc =3D (struct ptdesc *)table; + + pagetable_dtor(ptdesc); + pagetable_free(ptdesc); } =20 #endif /* CONFIG_MMU */ --=20 2.20.1