linux-kernel - [PATCH 8/8] riscv: add two hook functions of ftrace

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Message-Id: <20200217083223.2011-9-zong.li@sifive.com>
Date:   Mon, 17 Feb 2020 16:32:23 +0800
From:   Zong Li <zong.li@...ive.com>
To:     paul.walmsley@...ive.com, palmer@...belt.com,
        aou@...s.berkeley.edu, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Cc:     Zong Li <zong.li@...ive.com>
Subject: [PATCH 8/8] riscv: add two hook functions of ftrace

After the text section be mask as non-writable, the ftrace have to
change the permission of text for dynamic patching the intructions.
Add ftrace_arch_code_modify_prepare and
ftrace_arch_code_modify_post_process to change permission.

Signed-off-by: Zong Li <zong.li@...ive.com>
---
 arch/riscv/kernel/ftrace.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
index c40fdcdeb950..576df0807200 100644
--- a/arch/riscv/kernel/ftrace.c
+++ b/arch/riscv/kernel/ftrace.c
@@ -7,9 +7,27 @@
 
 #include <linux/ftrace.h>
 #include <linux/uaccess.h>
+#include <linux/memory.h>
+#include <asm/set_memory.h>
 #include <asm/cacheflush.h>
 
 #ifdef CONFIG_DYNAMIC_FTRACE
+int ftrace_arch_code_modify_prepare(void) __acquires(&text_mutex)
+{
+	mutex_lock(&text_mutex);
+	set_kernel_text_rw();
+	set_all_modules_text_rw();
+	return 0;
+}
+
+int ftrace_arch_code_modify_post_process(void) __releases(&text_mutex)
+{
+	set_all_modules_text_ro();
+	set_kernel_text_ro();
+	mutex_unlock(&text_mutex);
+	return 0;
+}
+
 static int ftrace_check_current_call(unsigned long hook_pos,
 				     unsigned int *expected)
 {
-- 
2.25.0