linux-kernel - [PATCH] mm: define pte_add

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Date:   Tue, 30 Jun 2020 11:18:52 +0800
From:   Wei Yang <richard.weiyang@...ux.alibaba.com>
To:     dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        akpm@...ux-foundation.org
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        Wei Yang <richard.weiyang@...ux.alibaba.com>
Subject: [PATCH] mm: define pte_add_end for consistency

When walking page tables, we define several helpers to get the address of
the next boundary. But we don't have one for pte level.

Let's define it and consolidate the code in several places.

Signed-off-by: Wei Yang <richard.weiyang@...ux.alibaba.com>
---
 arch/x86/mm/init_64.c   | 6 ++----
 include/linux/pgtable.h | 7 +++++++
 mm/kasan/init.c         | 4 +---
 3 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index dbae185511cd..f902fbd17f27 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -973,9 +973,7 @@ remove_pte_table(pte_t *pte_start, unsigned long addr, unsigned long end,
 
 	pte = pte_start + pte_index(addr);
 	for (; addr < end; addr = next, pte++) {
-		next = (addr + PAGE_SIZE) & PAGE_MASK;
-		if (next > end)
-			next = end;
+		next = pte_addr_end(addr, end);
 
 		if (!pte_present(*pte))
 			continue;
@@ -1558,7 +1556,7 @@ void register_page_bootmem_memmap(unsigned long section_nr,
 		get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO);
 
 		if (!boot_cpu_has(X86_FEATURE_PSE)) {
-			next = (addr + PAGE_SIZE) & PAGE_MASK;
+			next = pte_addr_end(addr, end);
 			pmd = pmd_offset(pud, addr);
 			if (pmd_none(*pmd))
 				continue;
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 32b6c52d41b9..0de09c6c89d2 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -706,6 +706,13 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
 })
 #endif
 
+#ifndef pte_addr_end
+#define pte_addr_end(addr, end)						\
+({	unsigned long __boundary = ((addr) + PAGE_SIZE) & PAGE_MASK;	\
+	(__boundary - 1 < (end) - 1) ? __boundary : (end);		\
+})
+#endif
+
 /*
  * When walking page tables, we usually want to skip any p?d_none entries;
  * and any p?d_bad entries - reporting the error before resetting to none.
diff --git a/mm/kasan/init.c b/mm/kasan/init.c
index fe6be0be1f76..89f748601f74 100644
--- a/mm/kasan/init.c
+++ b/mm/kasan/init.c
@@ -349,9 +349,7 @@ static void kasan_remove_pte_table(pte_t *pte, unsigned long addr,
 	unsigned long next;
 
 	for (; addr < end; addr = next, pte++) {
-		next = (addr + PAGE_SIZE) & PAGE_MASK;
-		if (next > end)
-			next = end;
+		next = pte_addr_end(addr, end);
 
 		if (!pte_present(*pte))
 			continue;
-- 
2.20.1 (Apple Git-117)