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fprobe: Skip exit_handler if entry_handler returns !0

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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: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu (Google) 2023-02-02 00:56:38 +09:00 committed by Steven Rostedt (Google)
parent 7e7ef1bfe5
commit 39d954200b
5 changed files with 32 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/fprobe.h
View File

@ -34,8 +34,8 @@ struct fprobe {
size_t entry_data_size; size_t entry_data_size;
int nr_maxactive; 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); struct pt_regs *regs, void *entry_data);
void (*exit_handler)(struct fprobe *fp, unsigned long entry_ip, void (*exit_handler)(struct fprobe *fp, unsigned long entry_ip,
struct pt_regs *regs, void *entry_data); struct pt_regs *regs, void *entry_data);
}; };

15
kernel/trace/bpf_trace.c
View File

@ -2644,12 +2644,23 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
return err; return err;
} }
static void static int
kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip, kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip,
struct pt_regs *regs, void *data) struct pt_regs *regs, void *data)
{ {
struct bpf_kprobe_multi_link *link; 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); link = container_of(fp, struct bpf_kprobe_multi_link, fp);
kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs); 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; goto error;
if (flags & BPF_F_KPROBE_MULTI_RETURN) 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 else
link->fp.entry_handler = kprobe_multi_link_handler; link->fp.entry_handler = kprobe_multi_link_handler;

14
kernel/trace/fprobe.c
View File

@ -27,7 +27,7 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
struct rethook_node *rh = NULL; struct rethook_node *rh = NULL;
struct fprobe *fp; struct fprobe *fp;
void *entry_data = NULL; void *entry_data = NULL;
int bit; int bit, ret;
fp = container_of(ops, struct fprobe, ops); fp = container_of(ops, struct fprobe, ops);
if (fprobe_disabled(fp)) if (fprobe_disabled(fp))
@ -52,11 +52,15 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
} }
if (fp->entry_handler) 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)
rethook_hook(rh, ftrace_get_regs(fregs), true);
/* 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: out:
ftrace_test_recursion_unlock(bit); ftrace_test_recursion_unlock(bit);
} }

7
lib/test_fprobe.c
View File

@ -37,7 +37,7 @@ static noinline u32 fprobe_selftest_nest_target(u32 value, u32 (*nest)(u32))
return nest(value + 2); 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) struct pt_regs *regs, void *data)
{ {
KUNIT_EXPECT_FALSE(current_test, preemptible()); 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; *(u32 *)data = entry_val;
} else } else
KUNIT_EXPECT_NULL(current_test, data); KUNIT_EXPECT_NULL(current_test, data);
return 0;
} }
static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip, 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); 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) struct pt_regs *regs, void *data)
{ {
KUNIT_EXPECT_FALSE(current_test, preemptible()); KUNIT_EXPECT_FALSE(current_test, preemptible());
return 0;
} }
static notrace void nest_exit_handler(struct fprobe *fp, unsigned long ip, static notrace void nest_exit_handler(struct fprobe *fp, unsigned long ip,

5
samples/fprobe/fprobe_example.c
View File

@ -48,8 +48,8 @@ static void show_backtrace(void)
stack_trace_print(stacks, len, 24); 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) struct pt_regs *regs, void *data)
{ {
if (use_trace) if (use_trace)
/* /*
@ -62,6 +62,7 @@ static void sample_entry_handler(struct fprobe *fp, unsigned long ip,
nhit++; nhit++;
if (stackdump) if (stackdump)
show_backtrace(); show_backtrace();
return 0;
} }
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,