netdev - [PATCH v2 bpf-next 2/4] bpf: Adjust F_NEEDS_EFFICIENT_UNALIGNED_ACCESS handling in test

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Message-Id: <20181130.210826.154045878905582065.davem@davemloft.net>
Date:   Fri, 30 Nov 2018 21:08:26 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     daniel@...earbox.net
CC:     ast@...nel.org, netdev@...r.kernel.org
Subject: [PATCH v2 bpf-next 2/4] bpf: Adjust
 F_NEEDS_EFFICIENT_UNALIGNED_ACCESS handling in test_verifier.c


Make it set the flag argument to bpf_verify_program() which will relax
the alignment restrictions.

Now all such test cases will go properly through the verifier even on
inefficient unaligned access architectures.

On inefficient unaligned access architectures do not try to run such
programs, instead mark the test case as passing but annotate the
result similarly to how it is done now in the presence of this flag.

So, we get complete full coverage for all REJECT test cases, and at
least verifier level coverage for ACCEPT test cases.

Signed-off-by: David S. Miller <davem@...emloft.net>
---
 tools/testing/selftests/bpf/test_verifier.c | 42 ++++++++++++++++-------------
 1 file changed, 24 insertions(+), 18 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 4224133..428a84d 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -14200,13 +14200,14 @@ static int set_admin(bool admin)
 static void do_test_single(struct bpf_test *test, bool unpriv,
 			   int *passes, int *errors)
 {
-	int fd_prog, expected_ret, reject_from_alignment;
+	int fd_prog, expected_ret, alignment_prevented_execution;
 	int prog_len, prog_type = test->prog_type;
 	struct bpf_insn *prog = test->insns;
 	int map_fds[MAX_NR_MAPS];
 	const char *expected_err;
 	uint32_t expected_val;
 	uint32_t retval;
+	__u32 pflags;
 	int i, err;
 
 	for (i = 0; i < MAX_NR_MAPS; i++)
@@ -14217,9 +14218,12 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
 	do_test_fixup(test, prog_type, prog, map_fds);
 	prog_len = probe_filter_length(prog);
 
-	fd_prog = bpf_verify_program(prog_type, prog, prog_len,
-				     test->flags & F_LOAD_WITH_STRICT_ALIGNMENT ?
-				     BPF_F_STRICT_ALIGNMENT : 0,
+	pflags = 0;
+	if (test->flags & F_LOAD_WITH_STRICT_ALIGNMENT)
+		pflags |= BPF_F_STRICT_ALIGNMENT;
+	if (test->flags & F_NEEDS_EFFICIENT_UNALIGNED_ACCESS)
+		pflags |= BPF_F_ANY_ALIGNMENT;
+	fd_prog = bpf_verify_program(prog_type, prog, prog_len, pflags,
 				     "GPL", 0, bpf_vlog, sizeof(bpf_vlog), 1);
 
 	expected_ret = unpriv && test->result_unpriv != UNDEF ?
@@ -14229,28 +14233,27 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
 	expected_val = unpriv && test->retval_unpriv ?
 		       test->retval_unpriv : test->retval;
 
-	reject_from_alignment = fd_prog < 0 &&
-				(test->flags & F_NEEDS_EFFICIENT_UNALIGNED_ACCESS) &&
-				strstr(bpf_vlog, "misaligned");
-#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
-	if (reject_from_alignment) {
-		printf("FAIL\nFailed due to alignment despite having efficient unaligned access: '%s'!\n",
-		       strerror(errno));
-		goto fail_log;
-	}
-#endif
+	alignment_prevented_execution = 0;
+
 	if (expected_ret == ACCEPT) {
-		if (fd_prog < 0 && !reject_from_alignment) {
+		if (fd_prog < 0) {
 			printf("FAIL\nFailed to load prog '%s'!\n",
 			       strerror(errno));
 			goto fail_log;
 		}
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+		if (fd_prog >= 0 &&
+		    (test->flags & F_NEEDS_EFFICIENT_UNALIGNED_ACCESS)) {
+			alignment_prevented_execution = 1;
+			goto test_ok;
+		}
+#endif
 	} else {
 		if (fd_prog >= 0) {
 			printf("FAIL\nUnexpected success to load!\n");
 			goto fail_log;
 		}
-		if (!strstr(bpf_vlog, expected_err) && !reject_from_alignment) {
+		if (!strstr(bpf_vlog, expected_err)) {
 			printf("FAIL\nUnexpected error message!\n\tEXP: %s\n\tRES: %s\n",
 			      expected_err, bpf_vlog);
 			goto fail_log;
@@ -14278,9 +14281,12 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
 			goto fail_log;
 		}
 	}
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+test_ok:
+#endif
 	(*passes)++;
-	printf("OK%s\n", reject_from_alignment ?
-	       " (NOTE: reject due to unknown alignment)" : "");
+	printf("OK%s\n", alignment_prevented_execution ?
+	       " (NOTE: not executed due to unknown alignment)" : "");
 close_fds:
 	close(fd_prog);
 	for (i = 0; i < MAX_NR_MAPS; i++)
-- 
2.1.2.532.g19b5d50