diff mbox series

[RFC,bpf-next,v1,7/8] selftests/bpf: allow checking xlated programs in verifier_* tests

Message ID 20240629094733.3863850-8-eddyz87@gmail.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series no_caller_saved_registers attribute for helper calls | expand

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netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 8 this patch: 8
netdev/build_tools success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers warning 10 maintainers not CCed: mykolal@fb.com haoluo@google.com jolsa@kernel.org cupertino.miranda@oracle.com shuah@kernel.org song@kernel.org john.fastabend@gmail.com kpsingh@kernel.org linux-kselftest@vger.kernel.org sdf@google.com
netdev/build_clang success Errors and warnings before: 8 this patch: 8
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 8 this patch: 8
netdev/checkpatch warning WARNING: line length of 81 exceeds 80 columns WARNING: line length of 83 exceeds 80 columns WARNING: line length of 85 exceeds 80 columns WARNING: line length of 88 exceeds 80 columns WARNING: line length of 95 exceeds 80 columns WARNING: line length of 96 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Eduard Zingerman June 29, 2024, 9:47 a.m. UTC 
Add a macro __xlated("...") for use with test_loader tests.

When such annotations are present for the test case:
- bpf_prog_get_info_by_fd() is used to get BPF program after all
  rewrites are applied by verifier.
- the program is diassembled and patterns specified in __xlated are
  searched for in the disassembly text.

__xlated matching follows the same mechanics as __msg:
each subsequent pattern is matched from the point where
previous pattern ended.

This allows to write tests like below, where the goal is to verify the
behavior of one of the of the transformations applied by verifier:

    SEC("raw_tp")
    __xlated("1: w0 = ")
    __xlated("2: r0 = &(void __percpu *)(r0)")
    __xlated("3: r0 = *(u32 *)(r0 +0)")
    __xlated("4: exit")
    __success __naked void simple(void)
    {
            asm volatile (
            "call %[bpf_get_smp_processor_id];"
            "exit;"
            :
            : __imm(bpf_get_smp_processor_id)
            : __clobber_all);
    }

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
---
 tools/testing/selftests/bpf/progs/bpf_misc.h |  6 ++
 tools/testing/selftests/bpf/test_loader.c    | 80 +++++++++++++++++++-
 2 files changed, 83 insertions(+), 3 deletions(-)

Comments

Andrii Nakryiko July 2, 2024, 12:42 a.m. UTC | #1 
On Sat, Jun 29, 2024 at 2:48 AM Eduard Zingerman <eddyz87@gmail.com> wrote:
>
> Add a macro __xlated("...") for use with test_loader tests.
>
> When such annotations are present for the test case:
> - bpf_prog_get_info_by_fd() is used to get BPF program after all
>   rewrites are applied by verifier.
> - the program is diassembled and patterns specified in __xlated are

typo: google says there is a typo in disassembled

>   searched for in the disassembly text.
>
> __xlated matching follows the same mechanics as __msg:
> each subsequent pattern is matched from the point where
> previous pattern ended.
>
> This allows to write tests like below, where the goal is to verify the
> behavior of one of the of the transformations applied by verifier:
>
>     SEC("raw_tp")
>     __xlated("1: w0 = ")
>     __xlated("2: r0 = &(void __percpu *)(r0)")
>     __xlated("3: r0 = *(u32 *)(r0 +0)")
>     __xlated("4: exit")
>     __success __naked void simple(void)
>     {
>             asm volatile (
>             "call %[bpf_get_smp_processor_id];"
>             "exit;"
>             :
>             : __imm(bpf_get_smp_processor_id)
>             : __clobber_all);
>     }
>
> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
> ---
>  tools/testing/selftests/bpf/progs/bpf_misc.h |  6 ++
>  tools/testing/selftests/bpf/test_loader.c    | 80 +++++++++++++++++++-
>  2 files changed, 83 insertions(+), 3 deletions(-)
>

Acked-by: Andrii Nakryiko <andrii@kernel.org>

> diff --git a/tools/testing/selftests/bpf/progs/bpf_misc.h b/tools/testing/selftests/bpf/progs/bpf_misc.h
> index 81097a3f15eb..fac131a23578 100644
> --- a/tools/testing/selftests/bpf/progs/bpf_misc.h
> +++ b/tools/testing/selftests/bpf/progs/bpf_misc.h
> @@ -26,6 +26,9 @@
>   *
>   * __regex           Same as __msg, but using a regular expression.
>   * __regex_unpriv    Same as __msg_unpriv but using a regular expression.
> + * __xlated          Expect a line in a disassembly log after verifier applies rewrites.
> + *                   Multiple __xlated attributes could be specified.
> + * __xlated_unpriv   Same as __xlated but for unprivileged mode.
>   *
>   * __success         Expect program load success in privileged mode.
>   * __success_unpriv  Expect program load success in unprivileged mode.
> @@ -63,11 +66,14 @@
>   */
>  #define __msg(msg)             __attribute__((btf_decl_tag("comment:test_expect_msg=" msg)))
>  #define __regex(regex)         __attribute__((btf_decl_tag("comment:test_expect_regex=" regex)))
> +#define __xlated(msg)          __attribute__((btf_decl_tag("comment:test_expect_xlated=" msg)))
>  #define __failure              __attribute__((btf_decl_tag("comment:test_expect_failure")))
>  #define __success              __attribute__((btf_decl_tag("comment:test_expect_success")))
>  #define __description(desc)    __attribute__((btf_decl_tag("comment:test_description=" desc)))
>  #define __msg_unpriv(msg)      __attribute__((btf_decl_tag("comment:test_expect_msg_unpriv=" msg)))
>  #define __regex_unpriv(regex)  __attribute__((btf_decl_tag("comment:test_expect_regex_unpriv=" regex)))
> +#define __xlated_unpriv(msg)   \
> +       __attribute__((btf_decl_tag("comment:test_expect_xlated_unpriv=" msg)))

nit: keep on a single line? you are ruining the beauty :)

>  #define __failure_unpriv       __attribute__((btf_decl_tag("comment:test_expect_failure_unpriv")))
>  #define __success_unpriv       __attribute__((btf_decl_tag("comment:test_expect_success_unpriv")))
>  #define __log_level(lvl)       __attribute__((btf_decl_tag("comment:test_log_level="#lvl)))

[...]
Eduard Zingerman July 2, 2024, 9:07 p.m. UTC | #2 
On Mon, 2024-07-01 at 17:42 -0700, Andrii Nakryiko wrote:

[...]

> > +#define __xlated_unpriv(msg)   \
> > +       __attribute__((btf_decl_tag("comment:test_expect_xlated_unpriv=" msg)))
> 
> nit: keep on a single line? you are ruining the beauty :)

checkpatch.pl won't be happy but makes sense.
Andrii Nakryiko July 2, 2024, 9:19 p.m. UTC | #3 
On Tue, Jul 2, 2024 at 2:07 PM Eduard Zingerman <eddyz87@gmail.com> wrote:
>
> On Mon, 2024-07-01 at 17:42 -0700, Andrii Nakryiko wrote:
>
> [...]
>
> > > +#define __xlated_unpriv(msg)   \
> > > +       __attribute__((btf_decl_tag("comment:test_expect_xlated_unpriv=" msg)))
> >
> > nit: keep on a single line? you are ruining the beauty :)
>
> checkpatch.pl won't be happy but makes sense.

checkpath.pl will cope just fine, let's keep the beauty of regularity intact
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/progs/bpf_misc.h b/tools/testing/selftests/bpf/progs/bpf_misc.h
index 81097a3f15eb..fac131a23578 100644
--- a/tools/testing/selftests/bpf/progs/bpf_misc.h
+++ b/tools/testing/selftests/bpf/progs/bpf_misc.h
@@ -26,6 +26,9 @@ 
  *
  * __regex           Same as __msg, but using a regular expression.
  * __regex_unpriv    Same as __msg_unpriv but using a regular expression.
+ * __xlated          Expect a line in a disassembly log after verifier applies rewrites.
+ *                   Multiple __xlated attributes could be specified.
+ * __xlated_unpriv   Same as __xlated but for unprivileged mode.
  *
  * __success         Expect program load success in privileged mode.
  * __success_unpriv  Expect program load success in unprivileged mode.
@@ -63,11 +66,14 @@ 
  */
 #define __msg(msg)		__attribute__((btf_decl_tag("comment:test_expect_msg=" msg)))
 #define __regex(regex)		__attribute__((btf_decl_tag("comment:test_expect_regex=" regex)))
+#define __xlated(msg)		__attribute__((btf_decl_tag("comment:test_expect_xlated=" msg)))
 #define __failure		__attribute__((btf_decl_tag("comment:test_expect_failure")))
 #define __success		__attribute__((btf_decl_tag("comment:test_expect_success")))
 #define __description(desc)	__attribute__((btf_decl_tag("comment:test_description=" desc)))
 #define __msg_unpriv(msg)	__attribute__((btf_decl_tag("comment:test_expect_msg_unpriv=" msg)))
 #define __regex_unpriv(regex)	__attribute__((btf_decl_tag("comment:test_expect_regex_unpriv=" regex)))
+#define __xlated_unpriv(msg)	\
+	__attribute__((btf_decl_tag("comment:test_expect_xlated_unpriv=" msg)))
 #define __failure_unpriv	__attribute__((btf_decl_tag("comment:test_expect_failure_unpriv")))
 #define __success_unpriv	__attribute__((btf_decl_tag("comment:test_expect_success_unpriv")))
 #define __log_level(lvl)	__attribute__((btf_decl_tag("comment:test_log_level="#lvl)))
diff --git a/tools/testing/selftests/bpf/test_loader.c b/tools/testing/selftests/bpf/test_loader.c
index d4bb68685ba5..8e5f051801db 100644
--- a/tools/testing/selftests/bpf/test_loader.c
+++ b/tools/testing/selftests/bpf/test_loader.c
@@ -7,6 +7,7 @@ 
 #include <bpf/btf.h>
 
 #include "autoconf_helper.h"
+#include "disasm_helpers.h"
 #include "unpriv_helpers.h"
 #include "cap_helpers.h"
 
@@ -19,10 +20,12 @@ 
 #define TEST_TAG_EXPECT_SUCCESS "comment:test_expect_success"
 #define TEST_TAG_EXPECT_MSG_PFX "comment:test_expect_msg="
 #define TEST_TAG_EXPECT_REGEX_PFX "comment:test_expect_regex="
+#define TEST_TAG_EXPECT_XLATED_PFX "comment:test_expect_xlated="
 #define TEST_TAG_EXPECT_FAILURE_UNPRIV "comment:test_expect_failure_unpriv"
 #define TEST_TAG_EXPECT_SUCCESS_UNPRIV "comment:test_expect_success_unpriv"
 #define TEST_TAG_EXPECT_MSG_PFX_UNPRIV "comment:test_expect_msg_unpriv="
 #define TEST_TAG_EXPECT_REGEX_PFX_UNPRIV "comment:test_expect_regex_unpriv="
+#define TEST_TAG_EXPECT_XLATED_PFX_UNPRIV "comment:test_expect_xlated_unpriv="
 #define TEST_TAG_LOG_LEVEL_PFX "comment:test_log_level="
 #define TEST_TAG_PROG_FLAGS_PFX "comment:test_prog_flags="
 #define TEST_TAG_DESCRIPTION_PFX "comment:test_description="
@@ -64,6 +67,7 @@  struct test_subspec {
 	char *name;
 	bool expect_failure;
 	struct msgs expect_msgs;
+	struct msgs expect_xlated;
 	int retval;
 	bool execute;
 };
@@ -117,6 +121,8 @@  static void free_test_spec(struct test_spec *spec)
 	/* Deallocate expect_msgs arrays. */
 	free_msgs(&spec->priv.expect_msgs);
 	free_msgs(&spec->unpriv.expect_msgs);
+	free_msgs(&spec->priv.expect_xlated);
+	free_msgs(&spec->unpriv.expect_xlated);
 
 	free(spec->priv.name);
 	free(spec->unpriv.name);
@@ -299,6 +305,18 @@  static int parse_test_spec(struct test_loader *tester,
 			if (err)
 				goto cleanup;
 			spec->mode_mask |= UNPRIV;
+		} else if (str_has_pfx(s, TEST_TAG_EXPECT_XLATED_PFX)) {
+			msg = s + sizeof(TEST_TAG_EXPECT_XLATED_PFX) - 1;
+			err = push_msg(msg, NULL, &spec->priv.expect_xlated);
+			if (err)
+				goto cleanup;
+			spec->mode_mask |= PRIV;
+		} else if (str_has_pfx(s, TEST_TAG_EXPECT_XLATED_PFX_UNPRIV)) {
+			msg = s + sizeof(TEST_TAG_EXPECT_XLATED_PFX_UNPRIV) - 1;
+			err = push_msg(msg, NULL, &spec->unpriv.expect_xlated);
+			if (err)
+				goto cleanup;
+			spec->mode_mask |= UNPRIV;
 		} else if (str_has_pfx(s, TEST_TAG_RETVAL_PFX)) {
 			val = s + sizeof(TEST_TAG_RETVAL_PFX) - 1;
 			err = parse_retval(val, &spec->priv.retval, "__retval");
@@ -402,6 +420,16 @@  static int parse_test_spec(struct test_loader *tester,
 					goto cleanup;
 			}
 		}
+		if (spec->unpriv.expect_xlated.cnt == 0) {
+			for (i = 0; i < spec->priv.expect_xlated.cnt; i++) {
+				struct expect_msg *msg = &spec->priv.expect_xlated.patterns[i];
+
+				err = push_msg(msg->substr, msg->regex_str,
+					       &spec->unpriv.expect_xlated);
+				if (err)
+					goto cleanup;
+			}
+		}
 	}
 
 	spec->valid = true;
@@ -449,7 +477,15 @@  static void emit_verifier_log(const char *log_buf, bool force)
 	fprintf(stdout, "VERIFIER LOG:\n=============\n%s=============\n", log_buf);
 }
 
-static void validate_msgs(char *log_buf, struct msgs *msgs)
+static void emit_xlated(const char *xlated, bool force)
+{
+	if (!force && env.verbosity == VERBOSE_NONE)
+		return;
+	fprintf(stdout, "XLATED:\n=============\n%s=============\n", xlated);
+}
+
+static void validate_msgs(char *log_buf, struct msgs *msgs,
+			  void (*emit_fn)(const char *buf, bool force))
 {
 	regmatch_t reg_match[1];
 	const char *match;
@@ -475,7 +511,7 @@  static void validate_msgs(char *log_buf, struct msgs *msgs)
 
 		if (!ASSERT_OK_PTR(match, "expect_msg")) {
 			if (env.verbosity == VERBOSE_NONE)
-				emit_verifier_log(log_buf, true /*force*/);
+				emit_fn(log_buf, true /*force*/);
 			for (j = 0; j <= i; j++) {
 				msg = &msgs->patterns[j];
 				fprintf(stderr, "%s %s: '%s'\n",
@@ -612,6 +648,35 @@  static bool should_do_test_run(struct test_spec *spec, struct test_subspec *subs
 	return true;
 }
 
+/* Get a disassembly of BPF program after verifier applies all rewrites */
+static int get_xlated_program_text(int prog_fd, char *text, size_t text_sz)
+{
+	__u32 insns_cnt = 0, i, insn_sz;
+	struct bpf_insn *insns = NULL;
+	char buf[64];
+	FILE *out = NULL;
+	int err;
+
+	err = get_xlated_program(prog_fd, &insns, &insns_cnt);
+	if (!ASSERT_OK(err, "get_xlated_program"))
+		goto out;
+	out = fmemopen(text, text_sz, "w");
+	if (!ASSERT_OK_PTR(out, "open_memstream"))
+		goto out;
+	for (i = 0; i < insns_cnt;) {
+		insn_sz = disasm_insn(insns + i, buf, sizeof(buf));
+		fprintf(out, "%d: %s\n", i, buf);
+		i += insn_sz;
+	}
+	fflush(out);
+
+out:
+	free(insns);
+	if (out)
+		fclose(out);
+	return err;
+}
+
 /* this function is forced noinline and has short generic name to look better
  * in test_progs output (in case of a failure)
  */
@@ -697,7 +762,16 @@  void run_subtest(struct test_loader *tester,
 		}
 	}
 	emit_verifier_log(tester->log_buf, false /*force*/);
-	validate_msgs(tester->log_buf, &subspec->expect_msgs);
+	validate_msgs(tester->log_buf, &subspec->expect_msgs, emit_verifier_log);
+
+	if (subspec->expect_xlated.cnt) {
+		err = get_xlated_program_text(bpf_program__fd(tprog),
+					      tester->log_buf, tester->log_buf_sz);
+		if (err)
+			goto tobj_cleanup;
+		emit_xlated(tester->log_buf, false /*force*/);
+		validate_msgs(tester->log_buf, &subspec->expect_xlated, emit_xlated);
+	}
 
 	if (should_do_test_run(spec, subspec)) {
 		/* For some reason test_verifier executes programs