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From:   Kefeng Wang <wangkefeng.wang@huawei.com>
To:     Russell King <linux@armlinux.org.uk>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
CC:     Alexander Potapenko <glider@google.com>,
        Marco Elver <elver@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Kefeng Wang <wangkefeng.wang@huawei.com>
Subject: [PATCH v2 1/3] ARM: mm: Provide set_memory_valid()
Date:   Wed, 3 Nov 2021 21:38:43 +0800
Message-ID: <20211103133845.78528-2-wangkefeng.wang@huawei.com>
In-Reply-To: <20211103133845.78528-1-wangkefeng.wang@huawei.com>
References: <20211103133845.78528-1-wangkefeng.wang@huawei.com>
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Precedence: bulk

This function validates and invalidates PTE entries, it will be used
in the later patch.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 arch/arm/include/asm/set_memory.h |  1 +
 arch/arm/mm/pageattr.c            | 42 +++++++++++++++++++++++--------
 2 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/arch/arm/include/asm/set_memory.h b/arch/arm/include/asm/set_memory.h
index ec17fc0fda7a..0211b9c5b14d 100644
--- a/arch/arm/include/asm/set_memory.h
+++ b/arch/arm/include/asm/set_memory.h
@@ -11,6 +11,7 @@ int set_memory_ro(unsigned long addr, int numpages);
 int set_memory_rw(unsigned long addr, int numpages);
 int set_memory_x(unsigned long addr, int numpages);
 int set_memory_nx(unsigned long addr, int numpages);
+int set_memory_valid(unsigned long addr, int numpages, int enable);
 #else
 static inline int set_memory_ro(unsigned long addr, int numpages) { return 0; }
 static inline int set_memory_rw(unsigned long addr, int numpages) { return 0; }
diff --git a/arch/arm/mm/pageattr.c b/arch/arm/mm/pageattr.c
index 9790ae3a8c68..c3c34fe714b0 100644
--- a/arch/arm/mm/pageattr.c
+++ b/arch/arm/mm/pageattr.c
@@ -32,14 +32,31 @@ static bool in_range(unsigned long start, unsigned long size,
 		size <= range_end - start;
 }
 
+/*
+ * This function assumes that the range is mapped with PAGE_SIZE pages.
+ */
+static int __change_memory_common(unsigned long start, unsigned long size,
+				pgprot_t set_mask, pgprot_t clear_mask)
+{
+	struct page_change_data data;
+	int ret;
+
+	data.set_mask = set_mask;
+	data.clear_mask = clear_mask;
+
+	ret = apply_to_page_range(&init_mm, start, size, change_page_range,
+				  &data);
+
+	flush_tlb_kernel_range(start, start + size);
+	return ret;
+}
+
 static int change_memory_common(unsigned long addr, int numpages,
 				pgprot_t set_mask, pgprot_t clear_mask)
 {
 	unsigned long start = addr & PAGE_MASK;
 	unsigned long end = PAGE_ALIGN(addr) + numpages * PAGE_SIZE;
 	unsigned long size = end - start;
-	int ret;
-	struct page_change_data data;
 
 	WARN_ON_ONCE(start != addr);
 
@@ -50,14 +67,7 @@ static int change_memory_common(unsigned long addr, int numpages,
 	    !in_range(start, size, VMALLOC_START, VMALLOC_END))
 		return -EINVAL;
 
-	data.set_mask = set_mask;
-	data.clear_mask = clear_mask;
-
-	ret = apply_to_page_range(&init_mm, start, size, change_page_range,
-					&data);
-
-	flush_tlb_kernel_range(start, end);
-	return ret;
+	return __change_memory_common(start, size, set_mask, clear_mask);
 }
 
 int set_memory_ro(unsigned long addr, int numpages)
@@ -87,3 +97,15 @@ int set_memory_x(unsigned long addr, int numpages)
 					__pgprot(0),
 					__pgprot(L_PTE_XN));
 }
+
+int set_memory_valid(unsigned long addr, int numpages, int enable)
+{
+	if (enable)
+		return __change_memory_common(addr, PAGE_SIZE * numpages,
+					      __pgprot(L_PTE_VALID),
+					      __pgprot(0));
+	else
+		return __change_memory_common(addr, PAGE_SIZE * numpages,
+					      __pgprot(0),
+					      __pgprot(L_PTE_VALID));
+}
-- 
2.26.2