1 files changed, 138 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
new file mode 100644
index 000000000..1bbd1d983
--- /dev/null
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <unistd.h>
+#include <linux/perf_event.h>
+#include <sys/mman.h>
+#include "trace_helpers.h"
+
+#define DEBUGFS "/sys/kernel/debug/tracing/"
+
+#define MAX_SYMS 300000
+static struct ksym syms[MAX_SYMS];
+static int sym_cnt;
+
+static int ksym_cmp(const void *p1, const void *p2)
+{
+	return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr;
+}
+
+int load_kallsyms(void)
+{
+	FILE *f = fopen("/proc/kallsyms", "r");
+	char func[256], buf[256];
+	char symbol;
+	void *addr;
+	int i = 0;
+
+	if (!f)
+		return -ENOENT;
+
+	while (fgets(buf, sizeof(buf), f)) {
+		if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3)
+			break;
+		if (!addr)
+			continue;
+		syms[i].addr = (long) addr;
+		syms[i].name = strdup(func);
+		i++;
+	}
+	fclose(f);
+	sym_cnt = i;
+	qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp);
+	return 0;
+}
+
+struct ksym *ksym_search(long key)
+{
+	int start = 0, end = sym_cnt;
+	int result;
+
+	/* kallsyms not loaded. return NULL */
+	if (sym_cnt <= 0)
+		return NULL;
+
+	while (start < end) {
+		size_t mid = start + (end - start) / 2;
+
+		result = key - syms[mid].addr;
+		if (result < 0)
+			end = mid;
+		else if (result > 0)
+			start = mid + 1;
+		else
+			return &syms[mid];
+	}
+
+	if (start >= 1 && syms[start - 1].addr < key &&
+	    key < syms[start].addr)
+		/* valid ksym */
+		return &syms[start - 1];
+
+	/* out of range. return _stext */
+	return &syms[0];
+}
+
+long ksym_get_addr(const char *name)
+{
+	int i;
+
+	for (i = 0; i < sym_cnt; i++) {
+		if (strcmp(syms[i].name, name) == 0)
+			return syms[i].addr;
+	}
+
+	return 0;
+}
+
+/* open kallsyms and read symbol addresses on the fly. Without caching all symbols,
+ * this is faster than load + find.
+ */
+int kallsyms_find(const char *sym, unsigned long long *addr)
+{
+	char type, name[500];
+	unsigned long long value;
+	int err = 0;
+	FILE *f;
+
+	f = fopen("/proc/kallsyms", "r");
+	if (!f)
+		return -EINVAL;
+
+	while (fscanf(f, "%llx %c %499s%*[^\n]\n", &value, &type, name) > 0) {
+		if (strcmp(name, sym) == 0) {
+			*addr = value;
+			goto out;
+		}
+	}
+	err = -ENOENT;
+
+out:
+	fclose(f);
+	return err;
+}
+
+void read_trace_pipe(void)
+{
+	int trace_fd;
+
+	trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
+	if (trace_fd < 0)
+		return;
+
+	while (1) {
+		static char buf[4096];
+		ssize_t sz;
+
+		sz = read(trace_fd, buf, sizeof(buf) - 1);
+		if (sz > 0) {
+			buf[sz] = 0;
+			puts(buf);
+		}
+	}
+}