netdev - [PATCH bpf-next 4/4] selftests/bpf: add reason of rejection in ld

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Date:   Fri, 20 May 2022 19:37:28 +0800
From:   Shung-Hsi Yu <shung-hsi.yu@...e.com>
To:     Shung-Hsi Yu <shung-hsi.yu@...e.com>,
        linux-kselftest@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org
CC:     Shuah Khan <shuah@...nel.org>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>
Subject: [PATCH bpf-next 4/4] selftests/bpf: add reason of rejection in ld_imm64

It may not be immediately clear why that ld_imm64 test cases are
rejected, especially for test1 and test2 where JMP to the 2nd
instruction of BPF_LD_IMM64 is performed.

Add brief explaination of why each test case in verifier/ld_imm64.c
should be rejected.

Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@...e.com>
---
 .../testing/selftests/bpf/verifier/ld_imm64.c | 20 ++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/bpf/verifier/ld_imm64.c b/tools/testing/selftests/bpf/verifier/ld_imm64.c
index f9297900cea6..021312641aaf 100644
--- a/tools/testing/selftests/bpf/verifier/ld_imm64.c
+++ b/tools/testing/selftests/bpf/verifier/ld_imm64.c
@@ -1,5 +1,6 @@
+/* Note: BPF_LD_IMM64 is composed of two instructions of class BPF_LD */
 {
-	"test1 ld_imm64",
+	"test1 ld_imm64: reject JMP to 2nd instruction of BPF_LD_IMM64",
 	.insns = {
 	BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1),
 	BPF_LD_IMM64(BPF_REG_0, 0),
@@ -14,7 +15,7 @@
 	.result = REJECT,
 },
 {
-	"test2 ld_imm64",
+	"test2 ld_imm64: reject JMP to 2nd instruction of BPF_LD_IMM64",
 	.insns = {
 	BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1),
 	BPF_LD_IMM64(BPF_REG_0, 0),
@@ -28,7 +29,7 @@
 	.result = REJECT,
 },
 {
-	"test3 ld_imm64",
+	"test3 ld_imm64: reject incomplete BPF_LD_IMM64 instruction",
 	.insns = {
 	BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1),
 	BPF_RAW_INSN(BPF_LD | BPF_IMM | BPF_DW, 0, 0, 0, 0),
@@ -42,7 +43,7 @@
 	.result = REJECT,
 },
 {
-	"test4 ld_imm64",
+	"test4 ld_imm64: reject incomplete BPF_LD_IMM64 instruction",
 	.insns = {
 	BPF_RAW_INSN(BPF_LD | BPF_IMM | BPF_DW, 0, 0, 0, 0),
 	BPF_EXIT_INSN(),
@@ -70,7 +71,7 @@
 	.retval = 1,
 },
 {
-	"test8 ld_imm64",
+	"test8 ld_imm64: reject 1st off!=0",
 	.insns = {
 	BPF_RAW_INSN(BPF_LD | BPF_IMM | BPF_DW, 0, 0, 1, 1),
 	BPF_RAW_INSN(0, 0, 0, 0, 1),
@@ -80,7 +81,7 @@
 	.result = REJECT,
 },
 {
-	"test9 ld_imm64",
+	"test9 ld_imm64: reject 2nd off!=0",
 	.insns = {
 	BPF_RAW_INSN(BPF_LD | BPF_IMM | BPF_DW, 0, 0, 0, 1),
 	BPF_RAW_INSN(0, 0, 0, 1, 1),
@@ -90,7 +91,7 @@
 	.result = REJECT,
 },
 {
-	"test10 ld_imm64",
+	"test10 ld_imm64: reject 2nd dst_reg!=0",
 	.insns = {
 	BPF_RAW_INSN(BPF_LD | BPF_IMM | BPF_DW, 0, 0, 0, 1),
 	BPF_RAW_INSN(0, BPF_REG_1, 0, 0, 1),
@@ -100,7 +101,7 @@
 	.result = REJECT,
 },
 {
-	"test11 ld_imm64",
+	"test11 ld_imm64: reject 2nd src_reg!=0",
 	.insns = {
 	BPF_RAW_INSN(BPF_LD | BPF_IMM | BPF_DW, 0, 0, 0, 1),
 	BPF_RAW_INSN(0, 0, BPF_REG_1, 0, 1),
@@ -113,6 +114,7 @@
 	"test12 ld_imm64",
 	.insns = {
 	BPF_MOV64_IMM(BPF_REG_1, 0),
+	/* BPF_REG_1 is interpreted as BPF_PSEUDO_MAP_FD */
 	BPF_RAW_INSN(BPF_LD | BPF_IMM | BPF_DW, 0, BPF_REG_1, 0, 1),
 	BPF_RAW_INSN(0, 0, 0, 0, 0),
 	BPF_EXIT_INSN(),
@@ -121,7 +123,7 @@
 	.result = REJECT,
 },
 {
-	"test13 ld_imm64",
+	"test13 ld_imm64: 2nd src_reg!=0",
 	.insns = {
 	BPF_MOV64_IMM(BPF_REG_1, 0),
 	BPF_RAW_INSN(BPF_LD | BPF_IMM | BPF_DW, 0, BPF_REG_1, 0, 1),
-- 
2.36.1