Subject: [PATCH v2 06/11] powerpc/mm/book3s64/hash: Applies counting method to monitor lockless pgtbl walks

From: Leonardo Bras <[email-masked]>
Date: Fri, 20 Sep 2019 16:50:42 -0300

Applies the counting-based method for monitoring all hash-related functions
that do lockless pagetable walks.

Signed-off-by: Leonardo Bras <[email-masked]>
---
 arch/powerpc/mm/book3s64/hash_tlb.c   | 2 ++
 arch/powerpc/mm/book3s64/hash_utils.c | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/arch/powerpc/mm/book3s64/hash_tlb.c b/arch/powerpc/mm/book3s64/hash_tlb.c
index 4a70d8dd39cd..5e5213c3f7c4 100644
--- a/arch/powerpc/mm/book3s64/hash_tlb.c
+++ b/arch/powerpc/mm/book3s64/hash_tlb.c
@@ -209,6 +209,7 @@ void __flush_hash_table_range(struct mm_struct *mm, unsigned long start,
 	 * to being hashed). This is not the most performance oriented
 	 * way to do things but is fine for our needs here.
 	 */
+	start_lockless_pgtbl_walk(mm);
 	local_irq_save(flags);
 	arch_enter_lazy_mmu_mode();
 	for (; start < end; start += PAGE_SIZE) {
@@ -230,6 +231,7 @@ void __flush_hash_table_range(struct mm_struct *mm, unsigned long start,
 	}
 	arch_leave_lazy_mmu_mode();
 	local_irq_restore(flags);
+	end_lockless_pgtbl_walk(mm);
 }
 
 void flush_tlb_pmd_range(struct mm_struct *mm, pmd_t *pmd, unsigned long addr)
diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
index b8ad14bb1170..299946cedc3a 100644
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -1322,6 +1322,7 @@ int hash_page_mm(struct mm_struct *mm, unsigned long ea,
 #endif /* CONFIG_PPC_64K_PAGES */
 
 	/* Get PTE and page size from page tables */
+	start_lockless_pgtbl_walk(mm);
 	ptep = find_linux_pte(pgdir, ea, &is_thp, &hugeshift);
 	if (ptep == NULL || !pte_present(*ptep)) {
 		DBG_LOW(" no PTE !\n");
@@ -1438,6 +1439,7 @@ int hash_page_mm(struct mm_struct *mm, unsigned long ea,
 	DBG_LOW(" -> rc=%d\n", rc);
 
 bail:
+	end_lockless_pgtbl_walk(mm);
 	exception_exit(prev_state);
 	return rc;
 }
@@ -1547,10 +1549,12 @@ 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.
 	 */
+	start_lockless_pgtbl_walk(mm);
 	local_irq_save(flags);
 
 	/*
@@ -1597,6 +1601,7 @@ void hash_preload(struct mm_struct *mm, unsigned long ea,
 				   pte_val(*ptep));
 out_exit:
 	local_irq_restore(flags);
+	end_lockless_pgtbl_walk(mm);
 }
 
 #ifdef CONFIG_PPC_MEM_KEYS
@@ -1613,11 +1618,13 @@ u16 get_mm_addr_key(struct mm_struct *mm, unsigned long address)
 	if (!mm || !mm->pgd)
 		return 0;
 
+	start_lockless_pgtbl_walk(mm);
 	local_irq_save(flags);
 	ptep = find_linux_pte(mm->pgd, address, NULL, NULL);
 	if (ptep)
 		pkey = pte_to_pkey_bits(pte_val(READ_ONCE(*ptep)));
 	local_irq_restore(flags);
+	end_lockless_pgtbl_walk(mm);
 
 	return pkey;
 }
-- 
2.20.1