strace/bpf-implement-decoding-of-BPF_BTF_LOAD-command.patch

From bc4224a8fa641819d42639ac5b3252681304bfc3 Mon Sep 17 00:00:00 2001
From: "Dmitry V. Levin" <ldv@altlinux.org>
Date: Wed, 13 Mar 2019 18:38:51 +0000
Subject: [PATCH 274/293] bpf: implement decoding of BPF_BTF_LOAD command

BPF_BTF_LOAD command was introduced by Linux commit
v4.18-rc1~114^2~417^2~1^2~5.

* bpf_attr.h (struct BPF_BTF_LOAD_struct): New type.
(BPF_BTF_LOAD_struct_size, expected_BPF_BTF_LOAD_struct_size): New
macros.
* bpf.c (BEGIN_BPF_CMD_DECODER(BPF_BTF_LOAD)): New bpf command decoder.
(SYS_FUNC(bpf)) <bpf_cmd_decoders[]>: Add BPF_CMD_ENTRY(BPF_BTF_LOAD).
* tests/bpf.c (union bpf_attr_data): Add
BPF_ATTR_DATA_FIELD(BPF_BTF_LOAD).
(init_BPF_BTF_LOAD_attr): New function.
(BPF_BTF_LOAD_checks): New checks array.
(main) <checks>: Add CHK(BPF_BTF_LOAD).
---
 bpf.c       | 13 +++++++++++++
 bpf_attr.h  | 12 ++++++++++++
 tests/bpf.c | 40 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 65 insertions(+)

diff --git a/bpf.c b/bpf.c
index fbd77dc..5fedbd1 100644
--- a/bpf.c
+++ b/bpf.c
@@ -825,6 +825,18 @@ BEGIN_BPF_CMD_DECODER(BPF_RAW_TRACEPOINT_OPEN)
 }
 END_BPF_CMD_DECODER(RVAL_DECODED)
 
+BEGIN_BPF_CMD_DECODER(BPF_BTF_LOAD)
+{
+	tprints("{btf=");
+	print_big_u64_addr(attr.btf);
+	printstrn(tcp, attr.btf, attr.btf_size);
+	PRINT_FIELD_ADDR64(", ", attr, btf_log_buf);
+	PRINT_FIELD_U(", ", attr, btf_size);
+	PRINT_FIELD_U(", ", attr, btf_log_size);
+	PRINT_FIELD_U(", ", attr, btf_log_level);
+}
+END_BPF_CMD_DECODER(RVAL_DECODED | RVAL_FD)
+
 SYS_FUNC(bpf)
 {
 	static const bpf_cmd_decoder_t bpf_cmd_decoders[] = {
@@ -846,6 +858,7 @@ SYS_FUNC(bpf)
 		BPF_CMD_ENTRY(BPF_OBJ_GET_INFO_BY_FD),
 		BPF_CMD_ENTRY(BPF_PROG_QUERY),
 		BPF_CMD_ENTRY(BPF_RAW_TRACEPOINT_OPEN),
+		BPF_CMD_ENTRY(BPF_BTF_LOAD),
 	};
 
 	const unsigned int cmd = tcp->u_arg[0];
diff --git a/bpf_attr.h b/bpf_attr.h
index b34983a..a04f79e 100644
--- a/bpf_attr.h
+++ b/bpf_attr.h
@@ -227,6 +227,18 @@ struct BPF_RAW_TRACEPOINT_OPEN_struct /* raw_tracepoint */ {
 	offsetofend(struct BPF_RAW_TRACEPOINT_OPEN_struct, prog_fd)
 #define expected_BPF_RAW_TRACEPOINT_OPEN_struct_size 12
 
+struct BPF_BTF_LOAD_struct {
+	uint64_t ATTRIBUTE_ALIGNED(8) btf;
+	uint64_t ATTRIBUTE_ALIGNED(8) btf_log_buf;
+	uint32_t btf_size;
+	uint32_t btf_log_size;
+	uint32_t btf_log_level;
+};
+
+# define BPF_BTF_LOAD_struct_size \
+	offsetofend(struct BPF_BTF_LOAD_struct, btf_log_level)
+# define expected_BPF_BTF_LOAD_struct_size 28
+
 struct bpf_map_info_struct {
 	uint32_t type;
 	uint32_t id;
diff --git a/tests/bpf.c b/tests/bpf.c
index b18a056..85b27d5 100644
--- a/tests/bpf.c
+++ b/tests/bpf.c
@@ -71,6 +71,7 @@ union bpf_attr_data {
 	BPF_ATTR_DATA_FIELD(BPF_OBJ_GET_INFO_BY_FD);
 	BPF_ATTR_DATA_FIELD(BPF_PROG_QUERY);
 	BPF_ATTR_DATA_FIELD(BPF_RAW_TRACEPOINT_OPEN);
+	BPF_ATTR_DATA_FIELD(BPF_BTF_LOAD);
 	char char_data[256];
 };
 
@@ -1078,6 +1079,44 @@ static struct bpf_attr_check BPF_RAW_TRACEPOINT_OPEN_checks[] = {
 	}
 };
 
+static void
+init_BPF_BTF_LOAD_attr(struct bpf_attr_check *check)
+{
+	static const char sample_btf_data[] = "bPf\0daTum";
+
+	static char *btf_data;
+	if (!btf_data)
+		btf_data = tail_memdup(sample_btf_data,
+				       sizeof(sample_btf_data) - 1);
+
+	struct BPF_BTF_LOAD_struct *attr = &check->data.BPF_BTF_LOAD_data;
+	attr->btf = (uintptr_t) btf_data;
+}
+
+static struct bpf_attr_check BPF_BTF_LOAD_checks[] = {
+	{
+		.data = { .BPF_BTF_LOAD_data = { .btf = 0 } },
+		.size = offsetofend(struct BPF_BTF_LOAD_struct, btf),
+		.str = "btf=NULL, btf_log_buf=NULL, btf_size=0"
+		       ", btf_log_size=0, btf_log_level=0"
+	},
+	{ /* 1 */
+		.data = { .BPF_BTF_LOAD_data = {
+			.btf_log_buf = 0xfacefeeddeadbeefULL,
+			.btf_size = 9,
+			.btf_log_size = -1U,
+			.btf_log_level = 42
+		} },
+		.size = offsetofend(struct BPF_BTF_LOAD_struct, btf_log_level),
+		.init_fn = init_BPF_BTF_LOAD_attr,
+		.str = "btf=\"bPf\\0daTum\""
+		       ", btf_log_buf=0xfacefeeddeadbeef"
+		       ", btf_size=9"
+		       ", btf_log_size=4294967295"
+		       ", btf_log_level=42"
+	}
+};
+
 
 #define CHK(cmd_) \
 	{ \
@@ -1108,6 +1147,7 @@ main(void)
 		CHK(BPF_OBJ_GET_INFO_BY_FD),
 		CHK(BPF_PROG_QUERY),
 		CHK(BPF_RAW_TRACEPOINT_OPEN),
+		CHK(BPF_BTF_LOAD),
 	};
 
 	page_size = get_page_size();
-- 
1.7.12.4