[PATCH v5 12/23] mm/ksw: add entry kprobe and exit fprobe management

[Jinchao Wang]

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 <wangjinchao...@gmail.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