Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
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 2/3] ARM: mm: Provide is_write_fault()
Date:   Wed, 3 Nov 2021 21:38:44 +0800
Message-ID: <20211103133845.78528-3-wangkefeng.wang@huawei.com>
In-Reply-To: <20211103133845.78528-1-wangkefeng.wang@huawei.com>
References: <20211103133845.78528-1-wangkefeng.wang@huawei.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 7BIT
Content-Type:   text/plain; charset=US-ASCII
Precedence: bulk

The function will check whether the fault is caused by a write access.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 arch/arm/mm/fault.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index bc8779d54a64..f7ab6dabe89f 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -207,6 +207,11 @@ static inline bool is_permission_fault(unsigned int fsr)
 	return false;
 }
 
+static inline bool is_write_fault(unsigned int fsr)
+{
+	return (fsr & FSR_WRITE) && !(fsr & FSR_CM);
+}
+
 static vm_fault_t __kprobes
 __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int flags,
 		unsigned long vma_flags, struct pt_regs *regs)
@@ -261,7 +266,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	if (user_mode(regs))
 		flags |= FAULT_FLAG_USER;
 
-	if ((fsr & FSR_WRITE) && !(fsr & FSR_CM)) {
+	if (is_write_fault(fsr)) {
 		flags |= FAULT_FLAG_WRITE;
 		vm_flags = VM_WRITE;
 	}
-- 
2.26.2