From 05e59e5fb0064c97a1c10921ecd549f2d4a58565 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Wed, 09 Oct 2024 06:14:40 +0000
Subject: [PATCH] add REDIRECT
---
kernel/arch/riscv/kernel/ftrace.c | 47 +++++++++++++++++++++++++++++++++--------------
1 files changed, 33 insertions(+), 14 deletions(-)
diff --git a/kernel/arch/riscv/kernel/ftrace.c b/kernel/arch/riscv/kernel/ftrace.c
index fa8530f..8693dfc 100644
--- a/kernel/arch/riscv/kernel/ftrace.c
+++ b/kernel/arch/riscv/kernel/ftrace.c
@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: GPL-2.0 */
+// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2013 Linaro Limited
* Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
@@ -7,9 +7,33 @@
#include <linux/ftrace.h>
#include <linux/uaccess.h>
+#include <linux/memory.h>
#include <asm/cacheflush.h>
+#include <asm/patch.h>
#ifdef CONFIG_DYNAMIC_FTRACE
+int ftrace_arch_code_modify_prepare(void) __acquires(&text_mutex)
+{
+ mutex_lock(&text_mutex);
+
+ /*
+ * The code sequences we use for ftrace can't be patched while the
+ * kernel is running, so we need to use stop_machine() to modify them
+ * for now. This doesn't play nice with text_mutex, we use this flag
+ * to elide the check.
+ */
+ riscv_patch_in_stop_machine = true;
+
+ return 0;
+}
+
+int ftrace_arch_code_modify_post_process(void) __releases(&text_mutex)
+{
+ riscv_patch_in_stop_machine = false;
+ mutex_unlock(&text_mutex);
+ return 0;
+}
+
static int ftrace_check_current_call(unsigned long hook_pos,
unsigned int *expected)
{
@@ -24,7 +48,8 @@
* Read the text we want to modify;
* return must be -EFAULT on read error
*/
- if (probe_kernel_read(replaced, (void *)hook_pos, MCOUNT_INSN_SIZE))
+ if (copy_from_kernel_nofault(replaced, (void *)hook_pos,
+ MCOUNT_INSN_SIZE))
return -EFAULT;
/*
@@ -32,7 +57,7 @@
* return must be -EINVAL on failed comparison
*/
if (memcmp(expected, replaced, sizeof(replaced))) {
- pr_err("%p: expected (%08x %08x) but get (%08x %08x)",
+ pr_err("%p: expected (%08x %08x) but got (%08x %08x)\n",
(void *)hook_pos, expected[0], expected[1], replaced[0],
replaced[1]);
return -EINVAL;
@@ -46,19 +71,13 @@
{
unsigned int call[2];
unsigned int nops[2] = {NOP4, NOP4};
- int ret = 0;
make_call(hook_pos, target, call);
- /* replace the auipc-jalr pair at once */
- ret = probe_kernel_write((void *)hook_pos, enable ? call : nops,
- MCOUNT_INSN_SIZE);
- /* return must be -EPERM on write error */
- if (ret)
+ /* Replace the auipc-jalr pair at once. Return -EPERM on write error. */
+ if (patch_text_nosync
+ ((void *)hook_pos, enable ? call : nops, MCOUNT_INSN_SIZE))
return -EPERM;
-
- smp_mb();
- flush_icache_range((void *)hook_pos, (void *)hook_pos + MCOUNT_INSN_SIZE);
return 0;
}
@@ -100,9 +119,9 @@
{
int out;
- ftrace_arch_code_modify_prepare();
+ mutex_lock(&text_mutex);
out = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
- ftrace_arch_code_modify_post_process();
+ mutex_unlock(&text_mutex);
return out;
}
--
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