Adding support to attach bpf program for entry and return probe
of the same function. This is common use case which at the moment
requires to create two kprobe multi links.
Adding new BPF_TRACE_KPROBE_MULTI_SESSION attach type that instructs
kernel to attach single link program to both entry and exit probe.
It's possible to control execution of the bpf program on return
probe simply by returning zero or non zero from the entry bpf
program execution to execute or not the bpf program on return
probe respectively.
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
include/uapi/linux/bpf.h | 1 +
kernel/bpf/syscall.c | 7 ++++++-
kernel/trace/bpf_trace.c | 28 ++++++++++++++++++++--------
tools/include/uapi/linux/bpf.h | 1 +
4 files changed, 28 insertions(+), 9 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index cee0a7915c08..fb8ecb199273 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1115,6 +1115,7 @@ enum bpf_attach_type {
BPF_CGROUP_UNIX_GETSOCKNAME,
BPF_NETKIT_PRIMARY,
BPF_NETKIT_PEER,
+ BPF_TRACE_KPROBE_MULTI_SESSION,
__MAX_BPF_ATTACH_TYPE
};
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 7d392ec83655..7c0cb1800b9f 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3974,11 +3974,15 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog,
if (prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI &&
attach_type != BPF_TRACE_KPROBE_MULTI)
return -EINVAL;
+ if (prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI_SESSION &&
+ attach_type != BPF_TRACE_KPROBE_MULTI_SESSION)
+ return -EINVAL;
if (prog->expected_attach_type == BPF_TRACE_UPROBE_MULTI &&
attach_type != BPF_TRACE_UPROBE_MULTI)
return -EINVAL;
if (attach_type != BPF_PERF_EVENT &&
attach_type != BPF_TRACE_KPROBE_MULTI &&
+ attach_type != BPF_TRACE_KPROBE_MULTI_SESSION &&
attach_type != BPF_TRACE_UPROBE_MULTI)
return -EINVAL;
return 0;
@@ -5239,7 +5243,8 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr)
case BPF_PROG_TYPE_KPROBE:
if (attr->link_create.attach_type == BPF_PERF_EVENT)
ret = bpf_perf_link_attach(attr, prog);
- else if (attr->link_create.attach_type == BPF_TRACE_KPROBE_MULTI)
+ else if (attr->link_create.attach_type == BPF_TRACE_KPROBE_MULTI ||
+ attr->link_create.attach_type == BPF_TRACE_KPROBE_MULTI_SESSION)
ret = bpf_kprobe_multi_link_attach(attr, prog);
else if (attr->link_create.attach_type == BPF_TRACE_UPROBE_MULTI)
ret = bpf_uprobe_multi_link_attach(attr, prog);
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index afb232b1d7c2..3b15a40f425f 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1631,6 +1631,17 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
}
}
+static bool is_kprobe_multi(const struct bpf_prog *prog)
+{
+ return prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI ||
+ prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI_SESSION;
+}
+
+static inline bool is_kprobe_multi_session(const struct bpf_prog *prog)
+{
+ return prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI_SESSION;
+}
+
static const struct bpf_func_proto *
kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
@@ -1646,13 +1657,13 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_override_return_proto;
#endif
case BPF_FUNC_get_func_ip:
- if (prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI)
+ if (is_kprobe_multi(prog))
return &bpf_get_func_ip_proto_kprobe_multi;
if (prog->expected_attach_type == BPF_TRACE_UPROBE_MULTI)
return &bpf_get_func_ip_proto_uprobe_multi;
return &bpf_get_func_ip_proto_kprobe;
case BPF_FUNC_get_attach_cookie:
- if (prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI)
+ if (is_kprobe_multi(prog))
return &bpf_get_attach_cookie_proto_kmulti;
if (prog->expected_attach_type == BPF_TRACE_UPROBE_MULTI)
return &bpf_get_attach_cookie_proto_umulti;
@@ -2834,10 +2845,11 @@ kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip,
void *data)
{
struct bpf_kprobe_multi_link *link;
+ int err;
link = container_of(fp, struct bpf_kprobe_multi_link, fp);
- kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs);
- return 0;
+ err = kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs);
+ return is_kprobe_multi_session(link->link.prog) ? err : 0;
}
static void
@@ -2981,7 +2993,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
if (sizeof(u64) != sizeof(void *))
return -EOPNOTSUPP;
- if (prog->expected_attach_type != BPF_TRACE_KPROBE_MULTI)
+ if (!is_kprobe_multi(prog))
return -EINVAL;
flags = attr->link_create.kprobe_multi.flags;
@@ -3062,10 +3074,10 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
if (err)
goto error;
- if (flags & BPF_F_KPROBE_MULTI_RETURN)
- link->fp.exit_handler = kprobe_multi_link_exit_handler;
- else
+ if (!(flags & BPF_F_KPROBE_MULTI_RETURN))
link->fp.entry_handler = kprobe_multi_link_handler;
+ if ((flags & BPF_F_KPROBE_MULTI_RETURN) || is_kprobe_multi_session(prog))
+ link->fp.exit_handler = kprobe_multi_link_exit_handler;
link->addrs = addrs;
link->cookies = cookies;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index cee0a7915c08..fb8ecb199273 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1115,6 +1115,7 @@ enum bpf_attach_type {
BPF_CGROUP_UNIX_GETSOCKNAME,
BPF_NETKIT_PRIMARY,
BPF_NETKIT_PEER,
+ BPF_TRACE_KPROBE_MULTI_SESSION,
__MAX_BPF_ATTACH_TYPE
};
--
2.44.0
