Commit deab5a35 authored by Qi Zheng's avatar Qi Zheng Committed by Andrew Morton
Browse files

riscv: pgtable: move pagetable_dtor() to __tlb_remove_table() 

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.

Link: https://lkml.kernel.org/r/b89d77c965507b1b102cbabe988e69365cb288b6.1736317725.git.zhengqi.arch@bytedance.com


Signed-off-by: default avatarQi Zheng <zhengqi.arch@bytedance.com>
Suggested-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarKevin Brodsky <kevin.brodsky@arm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 12359c03

arch/riscv/include/asm/pgalloc.h

+17 −21
Original line number Diff line number Diff line
@@ -15,13 +15,23 @@ 
#define __HAVE_ARCH_PUD_FREE

#include <asm-generic/pgalloc.h>



/*

 * 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 false use

 * SBI to perform TLB shootdown. To keep software pagetable walkers safe in 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-generic/tlb.h

 * for more details.

 */

static inline void riscv_tlb_remove_ptdesc(struct mmu_gather *tlb, void *pt)

{

	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);

	}

}



static inline void pmd_populate_kernel(struct mm_struct *mm,

	pmd_t *pmd, pte_t *pte)
@@ -97,24 +107,16 @@ 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 = 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));

}



static inline void __p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d,

				  unsigned long addr)

{

	if (pgtable_l5_enabled) {

		struct ptdesc *ptdesc = virt_to_ptdesc(p4d);



		pagetable_dtor(ptdesc);

	if (pgtable_l5_enabled)

		riscv_tlb_remove_ptdesc(tlb, virt_to_ptdesc(p4d));

}

}

#endif /* __PAGETABLE_PMD_FOLDED */



static inline void sync_kernel_mappings(pgd_t *pgd)
@@ -142,10 +144,7 @@ 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 = virt_to_ptdesc(pmd);



	pagetable_dtor(ptdesc);

	riscv_tlb_remove_ptdesc(tlb, ptdesc);

	riscv_tlb_remove_ptdesc(tlb, virt_to_ptdesc(pmd));

}



#endif /* __PAGETABLE_PMD_FOLDED */
@@ -153,10 +152,7 @@ static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd, 
static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,

				  unsigned long addr)

{

	struct ptdesc *ptdesc = page_ptdesc(pte);



	pagetable_dtor(ptdesc);

	riscv_tlb_remove_ptdesc(tlb, ptdesc);

	riscv_tlb_remove_ptdesc(tlb, page_ptdesc(pte));

}

#endif /* CONFIG_MMU */

arch/riscv/include/asm/tlb.h

+4 −10
Original line number Diff line number Diff line
@@ -11,19 +11,13 @@ struct mmu_gather; 
static void tlb_flush(struct mmu_gather *tlb);



#ifdef CONFIG_MMU

#include <linux/swap.h>



/*

 * 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 false use

 * SBI to perform TLB shootdown. To keep software pagetable walkers safe in 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-generic/tlb.h

 * for more details.

 */

static inline void __tlb_remove_table(void *table)

{

	free_page_and_swap_cache(table);

	struct ptdesc *ptdesc = (struct ptdesc *)table;



	pagetable_dtor(ptdesc);

	pagetable_free(ptdesc);

}



#endif /* CONFIG_MMU */