Message-ID: <20250924115124.194940-13-wangjinchao600@gmail.com>
Date: Wed, 24 Sep 2025 19:50:55 +0800
From: Jinchao Wang <wangjinchao600@...il.com>
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Cc: Jinchao Wang <wangjinchao600@...il.com>
Subject: [PATCH v5 12/23] mm/ksw: add entry kprobe and exit fprobe management

Provide ksw_stack_init() and ksw_stack_exit() to manage entry and exit
probes for the target function from ksw_get_config().

Signed-off-by: Jinchao Wang <wangjinchao600@...il.com>
---
 mm/kstackwatch/kstackwatch.h |   4 ++
 mm/kstackwatch/stack.c       | 101 +++++++++++++++++++++++++++++++++++
 2 files changed, 105 insertions(+)

diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h
index 850fc2b18a9c..4045890e5652 100644
--- a/mm/kstackwatch/kstackwatch.h
+++ b/mm/kstackwatch/kstackwatch.h
@@ -35,6 +35,10 @@ struct ksw_config {
 // singleton, only modified in kernel.c
 const struct ksw_config *ksw_get_config(void);
 
+/* stack management */
+int ksw_stack_init(void);
+void ksw_stack_exit(void);
+
 /* watch management */
 struct ksw_watchpoint {
 	struct perf_event *__percpu *event;
diff --git a/mm/kstackwatch/stack.c b/mm/kstackwatch/stack.c
index cec594032515..9f59f41d954c 100644
--- a/mm/kstackwatch/stack.c
+++ b/mm/kstackwatch/stack.c
@@ -1 +1,102 @@
 // SPDX-License-Identifier: GPL-2.0
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/atomic.h>
+#include <linux/fprobe.h>
+#include <linux/kprobes.h>
+#include <linux/kstackwatch_types.h>
+#include <linux/printk.h>
+
+#include "kstackwatch.h"
+
+static struct kprobe entry_probe;
+static struct fprobe exit_probe;
+
+static int ksw_stack_prepare_watch(struct pt_regs *regs,
+				   const struct ksw_config *config,
+				   ulong *watch_addr, u16 *watch_len)
+{
+	/* implement logic will be added in following patches */
+	*watch_addr = 0;
+	*watch_len = 0;
+	return 0;
+}
+
+static void ksw_stack_entry_handler(struct kprobe *p, struct pt_regs *regs,
+				    unsigned long flags)
+{
+	struct ksw_ctx *ctx = &current->ksw_ctx;
+	ulong watch_addr;
+	u16 watch_len;
+	int ret;
+
+	ret = ksw_watch_get(&ctx->wp);
+	if (ret)
+		return;
+
+	ret = ksw_stack_prepare_watch(regs, ksw_get_config(), &watch_addr,
+				      &watch_len);
+	if (ret) {
+		ksw_watch_off(ctx->wp);
+		ctx->wp = NULL;
+		pr_err("failed to prepare watch target: %d\n", ret);
+		return;
+	}
+
+	ret = ksw_watch_on(ctx->wp, watch_addr, watch_len);
+	if (ret) {
+		pr_err("failed to watch on depth:%d addr:0x%lx len:%u %d\n",
+		       ksw_get_config()->depth, watch_addr, watch_len, ret);
+		return;
+	}
+
+}
+
+static void ksw_stack_exit_handler(struct fprobe *fp, unsigned long ip,
+				   unsigned long ret_ip,
+				   struct ftrace_regs *regs, void *data)
+{
+	struct ksw_ctx *ctx = &current->ksw_ctx;
+
+
+	if (ctx->wp) {
+		ksw_watch_off(ctx->wp);
+		ctx->wp = NULL;
+		ctx->sp = 0;
+	}
+}
+
+int ksw_stack_init(void)
+{
+	int ret;
+	char *symbuf = NULL;
+
+	memset(&entry_probe, 0, sizeof(entry_probe));
+	entry_probe.symbol_name = ksw_get_config()->func_name;
+	entry_probe.offset = ksw_get_config()->func_offset;
+	entry_probe.post_handler = ksw_stack_entry_handler;
+	ret = register_kprobe(&entry_probe);
+	if (ret) {
+		pr_err("failed to register kprobe ret %d\n", ret);
+		return ret;
+	}
+
+	memset(&exit_probe, 0, sizeof(exit_probe));
+	exit_probe.exit_handler = ksw_stack_exit_handler;
+	symbuf = (char *)ksw_get_config()->func_name;
+
+	ret = register_fprobe_syms(&exit_probe, (const char **)&symbuf, 1);
+	if (ret < 0) {
+		pr_err("failed to register fprobe ret %d\n", ret);
+		unregister_kprobe(&entry_probe);
+		return ret;
+	}
+
+	return 0;
+}
+
+void ksw_stack_exit(void)
+{
+	unregister_fprobe(&exit_probe);
+	unregister_kprobe(&entry_probe);
+}
-- 
2.43.0

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