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Subject[RFC PATCH -tip 1/9] ftrace: Add pt_regs acceptable trace callback
Date
Add a new callback interface regs_func to ftrace_ops
which is an anonymous union to share the pointer
with func member. So, current ftrace user doesn't
need to change their callbacks.
This callback must be used with FTRACE_OPS_FL_SAVE_REGS.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/ftrace.h | 21 ++++++++++++++++++++-
kernel/trace/ftrace.c | 44 +++++++++++++++++++++++++++++++-------------
2 files changed, 51 insertions(+), 14 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 55e6d63..11abe4e 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -10,6 +10,8 @@
#include <linux/kallsyms.h>
#include <linux/linkage.h>
#include <linux/bitops.h>
+#include <linux/module.h>
+#include <linux/ptrace.h>
#include <linux/ktime.h>
#include <linux/sched.h>
#include <linux/types.h>
@@ -18,6 +20,14 @@

#include <asm/ftrace.h>

+/*
+ * If the arch supports saving the regs to the ftrace_ops
+ * then it should set this to 1.
+ */
+#ifndef ARCH_SUPPORTS_FTRACE_SAVE_REGS
+#define ARCH_SUPPORTS_FTRACE_SAVE_REGS 0
+#endif
+
struct module;
struct ftrace_hash;

@@ -30,6 +40,8 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
loff_t *ppos);

typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip);
+typedef void (*ftrace_regs_func_t)(unsigned long ip, unsigned long parent_ip,
+ struct pt_regs *regs);

/*
* FTRACE_OPS_FL_* bits denote the state of ftrace_ops struct and are
@@ -45,16 +57,22 @@ typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip);
* could be controled by following calls:
* ftrace_function_local_enable
* ftrace_function_local_disable
+ * SAVE_REGS - set manualy by ftrace_ops user to denote the ftrace_ops
+ * requests to pass pt_regs to callback.
*/
enum {
FTRACE_OPS_FL_ENABLED = 1 << 0,
FTRACE_OPS_FL_GLOBAL = 1 << 1,
FTRACE_OPS_FL_DYNAMIC = 1 << 2,
FTRACE_OPS_FL_CONTROL = 1 << 3,
+ FTRACE_OPS_FL_SAVE_REGS = 1 << 4,
};

struct ftrace_ops {
- ftrace_func_t func;
+ union {
+ ftrace_func_t func;
+ ftrace_regs_func_t regs_func;
+ };
struct ftrace_ops *next;
unsigned long flags;
int __percpu *disabled;
@@ -164,6 +182,7 @@ static inline int ftrace_function_local_disabled(struct ftrace_ops *ops)
}

extern void ftrace_stub(unsigned long a0, unsigned long a1);
+#define ftrace_regs_stub (ftrace_regs_func_t)(ftrace_stub)

#else /* !CONFIG_FUNCTION_TRACER */
/*
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a008663..357b15b 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -101,7 +101,9 @@ static struct ftrace_ops global_ops;
static struct ftrace_ops control_ops;

static void
-ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip);
+ftrace_ops_list_regs_func(unsigned long ip, unsigned long parent_ip,
+ struct pt_regs *regs);
+#define ftrace_ops_list_func (ftrace_func_t)(ftrace_ops_list_regs_func)

/*
* Traverse the ftrace_global_list, invoking all entries. The reason that we
@@ -112,8 +114,9 @@ ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip);
*
* Silly Alpha and silly pointer-speculation compiler optimizations!
*/
-static void ftrace_global_list_func(unsigned long ip,
- unsigned long parent_ip)
+static void
+ftrace_global_list_regs_func(unsigned long ip, unsigned long parent_ip,
+ struct pt_regs *regs)
{
struct ftrace_ops *op;

@@ -123,19 +126,24 @@ static void ftrace_global_list_func(unsigned long ip,
trace_recursion_set(TRACE_GLOBAL_BIT);
op = rcu_dereference_raw(ftrace_global_list); /*see above*/
while (op != &ftrace_list_end) {
- op->func(ip, parent_ip);
+ op->regs_func(ip, parent_ip, regs);
op = rcu_dereference_raw(op->next); /*see above*/
};
trace_recursion_clear(TRACE_GLOBAL_BIT);
}
+#define ftrace_global_list_func (ftrace_func_t)(ftrace_global_list_regs_func)

-static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip)
+static void ftrace_pid_regs_func(unsigned long ip, unsigned long parent_ip,
+ struct pt_regs *regs)
{
+ ftrace_regs_func_t func = (ftrace_regs_func_t)ftrace_pid_function;
+
if (!test_tsk_trace_trace(current))
return;

- ftrace_pid_function(ip, parent_ip);
+ func(ip, parent_ip, regs);
}
+#define ftrace_pid_func (ftrace_func_t)(ftrace_pid_regs_func)

static void set_ftrace_pid_function(ftrace_func_t func)
{
@@ -328,6 +336,10 @@ static int __register_ftrace_function(struct ftrace_ops *ops)
if (!core_kernel_data((unsigned long)ops))
ops->flags |= FTRACE_OPS_FL_DYNAMIC;

+ if ((ops->flags & FTRACE_OPS_FL_SAVE_REGS) &&
+ !ARCH_SUPPORTS_FTRACE_SAVE_REGS)
+ return -ENOSYS;
+
if (ops->flags & FTRACE_OPS_FL_GLOBAL) {
add_ftrace_list_ops(&ftrace_global_list, &global_ops, ops);
ops->flags |= FTRACE_OPS_FL_ENABLED;
@@ -1042,9 +1054,10 @@ static const struct ftrace_hash empty_hash = {
#define EMPTY_HASH ((struct ftrace_hash *)&empty_hash)

static struct ftrace_ops global_ops = {
- .func = ftrace_stub,
+ .regs_func = ftrace_regs_stub,
.notrace_hash = EMPTY_HASH,
.filter_hash = EMPTY_HASH,
+ .flags = FTRACE_OPS_FL_SAVE_REGS,
};

static DEFINE_MUTEX(ftrace_regex_lock);
@@ -3911,7 +3924,8 @@ void __init ftrace_init(void)
#else

static struct ftrace_ops global_ops = {
- .func = ftrace_stub,
+ .regs_func = ftrace_regs_stub,
+ .flags = FTRACE_OPS_FL_SAVE_REGS,
};

static int __init ftrace_nodyn_init(void)
@@ -3942,7 +3956,8 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip)
#endif /* CONFIG_DYNAMIC_FTRACE */

static void
-ftrace_ops_control_func(unsigned long ip, unsigned long parent_ip)
+ftrace_ops_control_regs_func(unsigned long ip, unsigned long parent_ip,
+ struct pt_regs *regs)
{
struct ftrace_ops *op;

@@ -3959,7 +3974,7 @@ ftrace_ops_control_func(unsigned long ip, unsigned long parent_ip)
while (op != &ftrace_list_end) {
if (!ftrace_function_local_disabled(op) &&
ftrace_ops_test(op, ip))
- op->func(ip, parent_ip);
+ op->regs_func(ip, parent_ip, regs);

op = rcu_dereference_raw(op->next);
};
@@ -3968,11 +3983,13 @@ ftrace_ops_control_func(unsigned long ip, unsigned long parent_ip)
}

static struct ftrace_ops control_ops = {
- .func = ftrace_ops_control_func,
+ .regs_func = ftrace_ops_control_regs_func,
+ .flags = FTRACE_OPS_FL_SAVE_REGS,
};

static void
-ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
+ftrace_ops_list_regs_func(unsigned long ip, unsigned long parent_ip,
+ struct pt_regs *regs)
{
struct ftrace_ops *op;

@@ -3988,7 +4005,8 @@ ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
op = rcu_dereference_raw(ftrace_ops_list);
while (op != &ftrace_list_end) {
if (ftrace_ops_test(op, ip))
- op->func(ip, parent_ip);
+ /* regs will be ignored if op->func is set */
+ op->regs_func(ip, parent_ip, regs);
op = rcu_dereference_raw(op->next);
};
preempt_enable_notrace();


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