Commit 39d95420 authored by Masami Hiramatsu (Google)'s avatar Masami Hiramatsu (Google) Committed by Steven Rostedt (Google)

fprobe: Skip exit_handler if entry_handler returns !0

Skip hooking function return and calling exit_handler if the
entry_handler() returns !0.

Link: https://lkml.kernel.org/r/167526699798.433354.10998365726830117303.stgit@mhiramat.roam.corp.google.com

Cc: Florent Revest <revest@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 7e7ef1bf
......@@ -34,7 +34,7 @@ struct fprobe {
size_t entry_data_size;
int nr_maxactive;
void (*entry_handler)(struct fprobe *fp, unsigned long entry_ip,
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);
......
......@@ -2644,12 +2644,23 @@ 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);
}
......@@ -2848,7 +2859,7 @@ 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;
......
......@@ -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);
ret = fp->entry_handler(fp, ip, ftrace_get_regs(fregs), entry_data);
if (rh)
/* 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);
}
......
......@@ -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,
......
......@@ -48,7 +48,7 @@ static void show_backtrace(void)
stack_trace_print(stacks, len, 24);
}
static void sample_entry_handler(struct fprobe *fp, unsigned long ip,
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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