[RFC PATCH v4 23/34] ftrace: notify kprobe when ftrace is initialized.

From: Wang Nan
Date: Mon Mar 02 2015 - 09:29:03 EST


Makes ftrace calls init_kprobes_on_ftrace() when ftrace_init()
finished. Before this call, marks kprobes on ftrace with
'KPROBE_FLAG_FTRACE_EARLY' instead of 'KPROBE_FLAG_FTRACE' to make
kprobe not to kprobe treats these kprobes as ftrace kprobes.

Following patches should convert such kprobes into kprobes on ftrace.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
---
include/linux/kprobes.h | 11 +++++++++++
kernel/kprobes.c | 17 ++++++++++++++++-
kernel/trace/ftrace.c | 2 ++
3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index bb2b2c6..96dc842 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -130,6 +130,8 @@ struct kprobe {
* this flag is only for optimized_kprobe.
*/
#define KPROBE_FLAG_FTRACE 8 /* probe is using ftrace */
+/* probe will use ftrace, but ftrace is not ready when registering */
+#define KPROBE_FLAG_FTRACE_EARLY 16

/* Has this kprobe gone ? */
static inline int kprobe_gone(struct kprobe *p)
@@ -269,6 +271,14 @@ extern void show_registers(struct pt_regs *regs);
extern void kprobes_inc_nmissed_count(struct kprobe *p);
extern bool arch_within_kprobe_blacklist(unsigned long addr);

+#if defined(CONFIG_EARLY_KPROBES) && defined(CONFIG_KPROBES_ON_FTRACE)
+extern void init_kprobes_on_ftrace(void);
+#else
+static inline void init_kprobes_on_ftrace(void)
+{
+}
+#endif // CONFIG_EARLY_KPROBES && CONFIG_KPROBES_ON_FTRACE
+
#ifdef CONFIG_EARLY_KPROBES

#define NR_EARLY_KPROBES_SLOTS CONFIG_NR_EARLY_KPROBES_SLOTS
@@ -453,6 +463,7 @@ extern int proc_kprobes_optimization_handler(struct ctl_table *table,
extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *ops, struct pt_regs *regs);
extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
+
#endif

int arch_check_ftrace_location(struct kprobe *p);
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 4b7b20a..b5e13ba 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -69,6 +69,11 @@

static int kprobes_initialized;
static int kprobes_blacklist_initialized;
+#if defined(CONFIG_KPROBES_ON_FTRACE) && defined(CONFIG_EARLY_KPROBES)
+static bool kprobes_on_ftrace_initialized __read_mostly = false;
+#else
+# define kprobes_on_ftrace_initialized false
+#endif

bool kprobes_is_early(void)
{
@@ -1497,7 +1502,10 @@ int __weak arch_check_ftrace_location(struct kprobe *p)
/* Given address is not on the instruction boundary */
if ((unsigned long)p->addr != ftrace_addr)
return -EILSEQ;
- p->flags |= KPROBE_FLAG_FTRACE;
+ if (unlikely(!kprobes_on_ftrace_initialized))
+ p->flags |= KPROBE_FLAG_FTRACE_EARLY;
+ else
+ p->flags |= KPROBE_FLAG_FTRACE;
#else /* !CONFIG_KPROBES_ON_FTRACE */
return -EINVAL;
#endif
@@ -2574,3 +2582,10 @@ module_init(init_kprobes);

/* defined in arch/.../kernel/kprobes.c */
EXPORT_SYMBOL_GPL(jprobe_return);
+
+#if defined(CONFIG_KPROBES_ON_FTRACE) && defined(CONFIG_EARLY_KPROBES)
+void init_kprobes_on_ftrace(void)
+{
+ kprobes_on_ftrace_initialized = true;
+}
+#endif
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 7fa88d0..5cb0269 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -23,6 +23,7 @@
#include <linux/kthread.h>
#include <linux/uaccess.h>
#include <linux/bsearch.h>
+#include <linux/kprobes.h>
#include <linux/module.h>
#include <linux/ftrace.h>
#include <linux/sysctl.h>
@@ -5022,6 +5023,7 @@ void __init ftrace_init(void)
if (ret)
pr_warning("Failed to register trace ftrace module exit notifier\n");

+ init_kprobes_on_ftrace();
set_ftrace_early_filters();

return;
--
1.8.4

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