This commit adds a test prog for vprintk which confirms that:
* bpf_trace_vprintk is writing to dmesg
* bpf_vprintk convenience macro works as expected
* >3 args are printed
Approach and code are borrowed from trace_printk test.
Signed-off-by: Dave Marchevsky <davemarchevsky@xxxxxx>
---
tools/testing/selftests/bpf/Makefile | 3 +-
.../selftests/bpf/prog_tests/trace_vprintk.c | 75 +++++++++++++++++++
.../selftests/bpf/progs/trace_vprintk.c | 25 +++++++
3 files changed, 102 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/trace_vprintk.c
create mode 100644 tools/testing/selftests/bpf/progs/trace_vprintk.c
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 2a58b7b5aea4..af5e7a1e9a7c 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -313,7 +313,8 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h \
linked_vars.skel.h linked_maps.skel.h
LSKELS := kfunc_call_test.c fentry_test.c fexit_test.c fexit_sleep.c \
- test_ksyms_module.c test_ringbuf.c atomics.c trace_printk.c
+ test_ksyms_module.c test_ringbuf.c atomics.c trace_printk.c \
+ trace_vprintk.c
SKEL_BLACKLIST += $$(LSKELS)
test_static_linked.skel.h-deps := test_static_linked1.o test_static_linked2.o
diff --git a/tools/testing/selftests/bpf/prog_tests/trace_vprintk.c b/tools/testing/selftests/bpf/prog_tests/trace_vprintk.c
new file mode 100644
index 000000000000..fd70427d2918
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/trace_vprintk.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include <test_progs.h>
+
+#include "trace_vprintk.lskel.h"
+
+#define TRACEBUF "/sys/kernel/debug/tracing/trace_pipe"
+#define SEARCHMSG "1,2,3,4,5,6,7,8,9,10"
+
+void test_trace_vprintk(void)
+{
+ int err, iter = 0, duration = 0, found = 0;
+ struct trace_vprintk__bss *bss;
+ struct trace_vprintk *skel;
+ char *buf = NULL;
+ FILE *fp = NULL;
+ size_t buflen;
+
+ skel = trace_vprintk__open();
+ if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
+ return;
+
+ err = trace_vprintk__load(skel);
+ if (CHECK(err, "skel_load", "failed to load skeleton: %d\n", err))
+ goto cleanup;
+
+ bss = skel->bss;
+
+ err = trace_vprintk__attach(skel);
+ if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err))
+ goto cleanup;
+
+ fp = fopen(TRACEBUF, "r");
+ if (CHECK(fp == NULL, "could not open trace buffer",
+ "error %d opening %s", errno, TRACEBUF))
+ goto cleanup;
+
+ /* We do not want to wait forever if this test fails... */
+ fcntl(fileno(fp), F_SETFL, O_NONBLOCK);
+
+ /* wait for tracepoint to trigger */
+ usleep(1);
+ trace_vprintk__detach(skel);
+
+ if (CHECK(bss->trace_vprintk_ran == 0,
+ "bpf_trace_vprintk never ran",
+ "ran == %d", bss->trace_vprintk_ran))
+ goto cleanup;
+
+ if (CHECK(bss->trace_vprintk_ret <= 0,
+ "bpf_trace_vprintk returned <= 0 value",
+ "got %d", bss->trace_vprintk_ret))
+ goto cleanup;
+
+ /* verify our search string is in the trace buffer */
+ while (getline(&buf, &buflen, fp) >= 0 || errno == EAGAIN) {
+ if (strstr(buf, SEARCHMSG) != NULL)
+ found++;
+ if (found == bss->trace_vprintk_ran)
+ break;
+ if (++iter > 1000)
+ break;
+ }
+
+ if (CHECK(!found, "message from bpf_trace_vprintk not found",
+ "no instance of %s in %s", SEARCHMSG, TRACEBUF))
+ goto cleanup;
+
+cleanup:
+ trace_vprintk__destroy(skel);
+ free(buf);
+ if (fp)
+ fclose(fp);
+}
diff --git a/tools/testing/selftests/bpf/progs/trace_vprintk.c b/tools/testing/selftests/bpf/progs/trace_vprintk.c
new file mode 100644
index 000000000000..993439a19e1e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/trace_vprintk.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+int trace_vprintk_ret = 0;
+int trace_vprintk_ran = 0;
+
+SEC("fentry/__x64_sys_nanosleep")
+int sys_enter(void *ctx)
+{
+ static const char one[] = "1";
+ static const char three[] = "3";
+ static const char five[] = "5";
+ static const char seven[] = "7";
+ static const char nine[] = "9";
+
+ trace_vprintk_ret = bpf_vprintk("%s,%d,%s,%d,%s,%d,%s,%d,%s,%d %d\n",
+ one, 2, three, 4, five, 6, seven, 8, nine, 10, ++trace_vprintk_ran);
+ return 0;
+}
--
2.30.2
