From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kvm-ppc@vger.kernel.org
Cc: leonardo@linux.ibm.com,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
npiggin@gmail.com, kirill@shutemov.name
Subject: [PATCH v2 05/22] powerpc/book3s64/hash: Use the pte_t address from the caller
Date: Thu, 19 Mar 2020 09:25:52 +0530 [thread overview]
Message-ID: <20200319035609.158654-6-aneesh.kumar@linux.ibm.com> (raw)
In-Reply-To: <20200319035609.158654-1-aneesh.kumar@linux.ibm.com>
Don't fetch the pte value using lockless page table walk. Instead use the value from the
caller. hash_preload is called with ptl lock held. So it is safe to use the
pte_t address directly.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
arch/powerpc/mm/book3s64/hash_utils.c | 27 +++++----------------------
1 file changed, 5 insertions(+), 22 deletions(-)
diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
index e2a7873c7760..81b4130ceb05 100644
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -1545,14 +1545,11 @@ static bool should_hash_preload(struct mm_struct *mm, unsigned long ea)
}
#endif
-static void hash_preload(struct mm_struct *mm, unsigned long ea,
+static void hash_preload(struct mm_struct *mm, pte_t *ptep, unsigned long ea,
bool is_exec, unsigned long trap)
{
- int hugepage_shift;
unsigned long vsid;
pgd_t *pgdir;
- pte_t *ptep;
- unsigned long flags;
int rc, ssize, update_flags = 0;
unsigned long access = _PAGE_PRESENT | _PAGE_READ | (is_exec ? _PAGE_EXEC : 0);
@@ -1574,30 +1571,18 @@ static void hash_preload(struct mm_struct *mm, unsigned long ea,
vsid = get_user_vsid(&mm->context, ea, ssize);
if (!vsid)
return;
- /*
- * Hash doesn't like irqs. Walking linux page table with irq disabled
- * saves us from holding multiple locks.
- */
- local_irq_save(flags);
- /*
- * THP pages use update_mmu_cache_pmd. We don't do
- * hash preload there. Hence can ignore THP here
- */
- ptep = find_current_mm_pte(pgdir, ea, NULL, &hugepage_shift);
- if (!ptep)
- goto out_exit;
-
- WARN_ON(hugepage_shift);
#ifdef CONFIG_PPC_64K_PAGES
/* If either H_PAGE_4K_PFN or cache inhibited is set (and we are on
* a 64K kernel), then we don't preload, hash_page() will take
* care of it once we actually try to access the page.
* That way we don't have to duplicate all of the logic for segment
* page size demotion here
+ * Called with PTL held, hence can be sure the value won't change in
+ * between.
*/
if ((pte_val(*ptep) & H_PAGE_4K_PFN) || pte_ci(*ptep))
- goto out_exit;
+ return;
#endif /* CONFIG_PPC_64K_PAGES */
/* Is that local to this CPU ? */
@@ -1622,8 +1607,6 @@ static void hash_preload(struct mm_struct *mm, unsigned long ea,
mm_ctx_user_psize(&mm->context),
mm_ctx_user_psize(&mm->context),
pte_val(*ptep));
-out_exit:
- local_irq_restore(flags);
}
/*
@@ -1674,7 +1657,7 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
return;
}
- hash_preload(vma->vm_mm, address, is_exec, trap);
+ hash_preload(vma->vm_mm, ptep, address, is_exec, trap);
}
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
--
2.24.1
next prev parent reply other threads:[~2020-03-19 4:08 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-19 3:55 [PATCH v2 00/22] Avoid IPI while updating page table entries Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 01/22] powerpc/pkeys: Avoid using lockless page table walk Aneesh Kumar K.V
2020-04-03 0:28 ` Ram Pai
2020-04-05 13:37 ` Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 02/22] powerpc/pkeys: Check vma before returning key fault error to the user Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 03/22] powerpc/mm/hash64: use _PAGE_PTE when checking for pte_present Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 04/22] powerpc/hash64: Restrict page table lookup using init_mm with __flush_hash_table_range Aneesh Kumar K.V
2020-03-19 3:55 ` Aneesh Kumar K.V [this message]
2020-03-19 3:55 ` [PATCH v2 06/22] powerpc/mce: Don't reload pte val in addr_to_pfn Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 07/22] powerpc/perf/callchain: Use __get_user_pages_fast in read_user_stack_slow Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 08/22] powerpc/kvm/book3s: switch from raw_spin_*lock to arch_spin_lock Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 09/22] powerpc/kvm/book3s: Add helper to walk partition scoped linux page table Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 10/22] powerpc/kvm/nested: Add helper to walk nested shadow " Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 11/22] powerpc/kvm/book3s: Use kvm helpers to walk shadow or secondary table Aneesh Kumar K.V
2020-03-19 3:55 ` [PATCH v2 12/22] powerpc/kvm/book3s: Add helper for host page table walk Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 13/22] powerpc/kvm/book3s: Use find_kvm_host_pte in page fault handler Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 14/22] powerpc/kvm/book3s: Use find_kvm_host_pte in h_enter Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 15/22] powerpc/kvm/book3s: use find_kvm_host_pte in pute_tce functions Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 16/22] powerpc/kvm/book3s: Avoid using rmap to protect parallel page table update Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 17/22] powerpc/kvm/book3s: use find_kvm_host_pte in kvmppc_book3s_instantiate_page Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 18/22] powerpc/kvm/book3s: Use find_kvm_host_pte in kvmppc_get_hpa Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 19/22] powerpc/kvm/book3s: Use pte_present instead of opencoding _PAGE_PRESENT check Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 20/22] powerpc/mm/book3s64: Avoid sending IPI on clearing PMD Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 21/22] mm: change pmdp_huge_get_and_clear_full take vm_area_struct as arg Aneesh Kumar K.V
2020-03-19 3:56 ` [PATCH v2 22/22] powerpc/mm/book3s64: Fix MADV_DONTNEED and parallel page fault race Aneesh Kumar K.V
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