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Message-Id: <166792259869.919356.8529453996904377437.stgit@devnote3>
Date: Wed, 9 Nov 2022 00:49:58 +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 5/9] fprobe: Skip exit_handler if entry_handler returns !0
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
Skip hooking function return and calling exit_handler if the
entry_handler() returns !0.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
---
include/linux/fprobe.h | 4 ++--
kernel/trace/bpf_trace.c | 15 +++++++++++++--
kernel/trace/fprobe.c | 14 +++++++++-----
lib/test_fprobe.c | 7 +++++--
samples/fprobe/fprobe_example.c | 5 +++--
5 files changed, 32 insertions(+), 13 deletions(-)
diff --git a/include/linux/fprobe.h b/include/linux/fprobe.h
index 678f741a7b33..47fefc7f363b 100644
--- a/include/linux/fprobe.h
+++ b/include/linux/fprobe.h
@@ -34,8 +34,8 @@ struct fprobe {
size_t entry_data_size;
int nr_maxactive;
- void (*entry_handler)(struct fprobe *fp, unsigned long entry_ip,
- struct pt_regs *regs, void *entry_data);
+ int (*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);
};
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 68c369452680..dadcddb6a429 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2623,12 +2623,23 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
return err;
}
-static void
+static int
kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip,
struct pt_regs *regs, void *data)
{
struct bpf_kprobe_multi_link *link;
+ link = container_of(fp, struct bpf_kprobe_multi_link, fp);
+ kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs);
+ return 0;
+}
+
+static void
+kprobe_multi_link_exit_handler(struct fprobe *fp, unsigned long fentry_ip,
+ struct pt_regs *regs, void *data)
+{
+ struct bpf_kprobe_multi_link *link;
+
link = container_of(fp, struct bpf_kprobe_multi_link, fp);
kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs);
}
@@ -2754,7 +2765,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
goto error;
if (flags & BPF_F_KPROBE_MULTI_RETURN)
- link->fp.exit_handler = kprobe_multi_link_handler;
+ link->fp.exit_handler = kprobe_multi_link_exit_handler;
else
link->fp.entry_handler = kprobe_multi_link_handler;
diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index f222848571f2..9abb3905bc8e 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -27,7 +27,7 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
struct rethook_node *rh = NULL;
struct fprobe *fp;
void *entry_data = NULL;
- int bit;
+ int bit, ret;
fp = container_of(ops, struct fprobe, ops);
if (fprobe_disabled(fp))
@@ -52,11 +52,15 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
}
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);
+ ret = fp->entry_handler(fp, ip, ftrace_get_regs(fregs), entry_data);
+ /* If entry_handler returns !0, nmissed is not counted. */
+ if (rh) {
+ if (ret)
+ rethook_recycle(rh);
+ else
+ rethook_hook(rh, ftrace_get_regs(fregs), true);
+ }
out:
ftrace_test_recursion_unlock(bit);
}
diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
index 976fb3f7cb01..e78176d252ae 100644
--- a/lib/test_fprobe.c
+++ b/lib/test_fprobe.c
@@ -37,7 +37,7 @@ static noinline u32 fprobe_selftest_nest_target(u32 value, u32 (*nest)(u32))
return nest(value + 2);
}
-static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip,
+static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip,
struct pt_regs *regs, void *data)
{
KUNIT_EXPECT_FALSE(current_test, preemptible());
@@ -51,6 +51,8 @@ static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip,
*(u32 *)data = entry_val;
} else
KUNIT_EXPECT_NULL(current_test, data);
+
+ return 0;
}
static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip,
@@ -74,10 +76,11 @@ static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip,
KUNIT_EXPECT_NULL(current_test, data);
}
-static notrace void nest_entry_handler(struct fprobe *fp, unsigned long ip,
+static notrace int nest_entry_handler(struct fprobe *fp, unsigned long ip,
struct pt_regs *regs, void *data)
{
KUNIT_EXPECT_FALSE(current_test, preemptible());
+ return 0;
}
static notrace void nest_exit_handler(struct fprobe *fp, unsigned long ip,
diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c
index dd794990ad7e..4efc8feb6277 100644
--- a/samples/fprobe/fprobe_example.c
+++ b/samples/fprobe/fprobe_example.c
@@ -48,8 +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, void *data)
+static int sample_entry_handler(struct fprobe *fp, unsigned long ip,
+ struct pt_regs *regs, void *data)
{
if (use_trace)
/*
@@ -62,6 +62,7 @@ static void sample_entry_handler(struct fprobe *fp, unsigned long ip,
nhit++;
if (stackdump)
show_backtrace();
+ return 0;
}
static void sample_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs,
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