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Message-Id: <166792256330.919356.14776044963704066797.stgit@devnote3>
Date: Wed, 9 Nov 2022 00:49:23 +0900
From: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
To: linux-trace-kernel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
mhiramat@...nel.org, Florent Revest <revest@...omium.org>,
Mark Rutland <mark.rutland@....com>,
Will Deacon <will@...nel.org>
Subject: [RFC PATCH 1/9] fprobe: Pass entry_data to handlers
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
Pass the private entry_data to the entry and exit handlers so that
they can share the context data, something like saved function
arguments etc.
User must specify the private entry_data size by @entry_data_size
field before registering the fprobe.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
---
include/linux/fprobe.h | 8 ++++++--
kernel/trace/bpf_trace.c | 2 +-
kernel/trace/fprobe.c | 21 ++++++++++++++-------
lib/test_fprobe.c | 6 ++++--
samples/fprobe/fprobe_example.c | 6 ++++--
5 files changed, 29 insertions(+), 14 deletions(-)
diff --git a/include/linux/fprobe.h b/include/linux/fprobe.h
index 1c2bde0ead73..e0d4e6136249 100644
--- a/include/linux/fprobe.h
+++ b/include/linux/fprobe.h
@@ -13,6 +13,7 @@
* @nmissed: The counter for missing events.
* @flags: The status flag.
* @rethook: The rethook data structure. (internal data)
+ * @entry_data_size: The private data storage size.
* @entry_handler: The callback function for function entry.
* @exit_handler: The callback function for function exit.
*/
@@ -29,9 +30,12 @@ struct fprobe {
unsigned long nmissed;
unsigned int flags;
struct rethook *rethook;
+ size_t entry_data_size;
- void (*entry_handler)(struct fprobe *fp, unsigned long entry_ip, struct pt_regs *regs);
- void (*exit_handler)(struct fprobe *fp, unsigned long entry_ip, struct pt_regs *regs);
+ void (*entry_handler)(struct fprobe *fp, unsigned long entry_ip,
+ struct pt_regs *regs, void *entry_data);
+ void (*exit_handler)(struct fprobe *fp, unsigned long entry_ip,
+ struct pt_regs *regs, void *entry_data);
};
/* This fprobe is soft-disabled. */
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 1ed08967fb97..68c369452680 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2625,7 +2625,7 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
static void
kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip,
- struct pt_regs *regs)
+ struct pt_regs *regs, void *data)
{
struct bpf_kprobe_multi_link *link;
diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index e8143e368074..fa25d09c9d57 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -17,14 +17,16 @@
struct fprobe_rethook_node {
struct rethook_node node;
unsigned long entry_ip;
+ char data[];
};
static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *ops, struct ftrace_regs *fregs)
{
struct fprobe_rethook_node *fpr;
- struct rethook_node *rh;
+ struct rethook_node *rh = NULL;
struct fprobe *fp;
+ void *entry_data = NULL;
int bit;
fp = container_of(ops, struct fprobe, ops);
@@ -37,9 +39,6 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
return;
}
- if (fp->entry_handler)
- fp->entry_handler(fp, ip, ftrace_get_regs(fregs));
-
if (fp->exit_handler) {
rh = rethook_try_get(fp->rethook);
if (!rh) {
@@ -48,9 +47,16 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
}
fpr = container_of(rh, struct fprobe_rethook_node, node);
fpr->entry_ip = ip;
- rethook_hook(rh, ftrace_get_regs(fregs), true);
+ if (fp->entry_data_size)
+ entry_data = fpr->data;
}
+ if (fp->entry_handler)
+ fp->entry_handler(fp, ip, ftrace_get_regs(fregs), entry_data);
+
+ if (rh)
+ rethook_hook(rh, ftrace_get_regs(fregs), true);
+
out:
ftrace_test_recursion_unlock(bit);
}
@@ -81,7 +87,8 @@ static void fprobe_exit_handler(struct rethook_node *rh, void *data,
fpr = container_of(rh, struct fprobe_rethook_node, node);
- fp->exit_handler(fp, fpr->entry_ip, regs);
+ fp->exit_handler(fp, fpr->entry_ip, regs,
+ fp->entry_data_size ? (void *)fpr->data : NULL);
}
NOKPROBE_SYMBOL(fprobe_exit_handler);
@@ -146,7 +153,7 @@ static int fprobe_init_rethook(struct fprobe *fp, int num)
for (i = 0; i < size; i++) {
struct fprobe_rethook_node *node;
- node = kzalloc(sizeof(*node), GFP_KERNEL);
+ node = kzalloc(sizeof(*node) + fp->entry_data_size, GFP_KERNEL);
if (!node) {
rethook_free(fp->rethook);
fp->rethook = NULL;
diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
index e0381b3ec410..34fa5a5bbda1 100644
--- a/lib/test_fprobe.c
+++ b/lib/test_fprobe.c
@@ -30,7 +30,8 @@ static noinline u32 fprobe_selftest_target2(u32 value)
return (value / div_factor) + 1;
}
-static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs)
+static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip,
+ struct pt_regs *regs, void *data)
{
KUNIT_EXPECT_FALSE(current_test, preemptible());
/* This can be called on the fprobe_selftest_target and the fprobe_selftest_target2 */
@@ -39,7 +40,8 @@ static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip, struct
entry_val = (rand1 / div_factor);
}
-static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs)
+static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip,
+ struct pt_regs *regs, void *data)
{
unsigned long ret = regs_return_value(regs);
diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c
index e22da8573116..dd794990ad7e 100644
--- a/samples/fprobe/fprobe_example.c
+++ b/samples/fprobe/fprobe_example.c
@@ -48,7 +48,8 @@ static void show_backtrace(void)
stack_trace_print(stacks, len, 24);
}
-static void sample_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs)
+static void sample_entry_handler(struct fprobe *fp, unsigned long ip,
+ struct pt_regs *regs, void *data)
{
if (use_trace)
/*
@@ -63,7 +64,8 @@ static void sample_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_
show_backtrace();
}
-static void sample_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs)
+static void sample_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs,
+ void *data)
{
unsigned long rip = instruction_pointer(regs);
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