[RFC PATCH 3/5] libbpf, bpftool: Support BPF_PROG_TYPE_OOM_POLICY

[Chuyi Zhou]

Support BPF_PROG_TYPE_OOM_POLICY program in libbpf and bpftool, so that
we can identify and use BPF_PROG_TYPE_OOM_POLICY in our application.

Signed-off-by: Chuyi Zhou <zhouchuyi@xxxxxxxxxxxxx>
---
 tools/bpf/bpftool/common.c     |  1 +
 tools/include/uapi/linux/bpf.h | 14 ++++++++++++++
 tools/lib/bpf/libbpf.c         |  3 +++
 tools/lib/bpf/libbpf_probes.c  |  2 ++
 4 files changed, 20 insertions(+)

diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index cc6e6aae2447..c5c311299c4a 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -1089,6 +1089,7 @@ const char *bpf_attach_type_input_str(enum bpf_attach_type t)
 	case BPF_TRACE_FENTRY:			return "fentry";
 	case BPF_TRACE_FEXIT:			return "fexit";
 	case BPF_MODIFY_RETURN:			return "mod_ret";
+	case BPF_OOM_POLICY:			return "oom_policy";
 	case BPF_SK_REUSEPORT_SELECT:		return "sk_skb_reuseport_select";
 	case BPF_SK_REUSEPORT_SELECT_OR_MIGRATE:	return "sk_skb_reuseport_select_or_migrate";
 	default:	return libbpf_bpf_attach_type_str(t);
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 60a9d59beeab..9da0d61cf703 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -987,6 +987,7 @@ enum bpf_prog_type {
 	BPF_PROG_TYPE_SK_LOOKUP,
 	BPF_PROG_TYPE_SYSCALL, /* a program that can execute syscalls */
 	BPF_PROG_TYPE_NETFILTER,
+	BPF_PROG_TYPE_OOM_POLICY,
 };
 
 enum bpf_attach_type {
@@ -1036,6 +1037,7 @@ enum bpf_attach_type {
 	BPF_LSM_CGROUP,
 	BPF_STRUCT_OPS,
 	BPF_NETFILTER,
+	BPF_OOM_POLICY,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -6825,6 +6827,18 @@ struct bpf_cgroup_dev_ctx {
 	__u32 minor;
 };
 
+enum {
+	BPF_OOM_CMP_EQUAL   = (1ULL << 0),
+	BPF_OOM_CMP_GREATER = (1ULL << 1),
+	BPF_OOM_CMP_LESS    = (1ULL << 2),
+};
+
+struct bpf_oom_ctx {
+	__u64 cg_id_1;
+	__u64 cg_id_2;
+	__u8  cmp_ret;
+};
+
 struct bpf_raw_tracepoint_args {
 	__u64 args[0];
 };
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 214f828ece6b..10496bb9b3bc 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -118,6 +118,7 @@ static const char * const attach_type_name[] = {
 	[BPF_TRACE_KPROBE_MULTI]	= "trace_kprobe_multi",
 	[BPF_STRUCT_OPS]		= "struct_ops",
 	[BPF_NETFILTER]			= "netfilter",
+	[BPF_OOM_POLICY]		= "oom_policy",
 };
 
 static const char * const link_type_name[] = {
@@ -204,6 +205,7 @@ static const char * const prog_type_name[] = {
 	[BPF_PROG_TYPE_SK_LOOKUP]		= "sk_lookup",
 	[BPF_PROG_TYPE_SYSCALL]			= "syscall",
 	[BPF_PROG_TYPE_NETFILTER]		= "netfilter",
+	[BPF_PROG_TYPE_OOM_POLICY]		= "oom_policy",
 };
 
 static int __base_pr(enum libbpf_print_level level, const char *format,
@@ -8738,6 +8740,7 @@ static const struct bpf_sec_def section_defs[] = {
 	SEC_DEF("struct_ops.s+",	STRUCT_OPS, 0, SEC_SLEEPABLE),
 	SEC_DEF("sk_lookup",		SK_LOOKUP, BPF_SK_LOOKUP, SEC_ATTACHABLE),
 	SEC_DEF("netfilter",		NETFILTER, BPF_NETFILTER, SEC_NONE),
+	SEC_DEF("oom_policy",       OOM_POLICY, BPF_OOM_POLICY, SEC_ATTACHABLE_OPT),
 };
 
 static size_t custom_sec_def_cnt;
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index 9c4db90b92b6..dbac3e98a2d7 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -129,6 +129,8 @@ static int probe_prog_load(enum bpf_prog_type prog_type,
 	case BPF_PROG_TYPE_LIRC_MODE2:
 		opts.expected_attach_type = BPF_LIRC_MODE2;
 		break;
+	case BPF_PROG_TYPE_OOM_POLICY:
+		opts.expected_attach_type = BPF_OOM_POLICY;
 	case BPF_PROG_TYPE_TRACING:
 	case BPF_PROG_TYPE_LSM:
 		opts.log_buf = buf;
-- 
2.20.1