bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 76 insertions, 0 deletions

diff --git a/tools/perf/util/units.c b/tools/perf/util/units.c
new file mode 100644
index 000000000..0bbacf5a2
--- /dev/null
+++ b/tools/perf/util/units.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "units.h"
+#include <inttypes.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+#include <linux/kernel.h>
+#include <linux/time64.h>
+
+unsigned long parse_tag_value(const char *str, struct parse_tag *tags)
+{
+	struct parse_tag *i = tags;
+
+	while (i->tag) {
+		const char *s = strchr(str, i->tag);
+
+		if (s) {
+			unsigned long int value;
+			char *endptr;
+
+			value = strtoul(str, &endptr, 10);
+			if (s != endptr)
+				break;
+
+			if (value > ULONG_MAX / i->mult)
+				break;
+			value *= i->mult;
+			return value;
+		}
+		i++;
+	}
+
+	return (unsigned long) -1;
+}
+
+double convert_unit_double(double value, char *unit)
+{
+	*unit = ' ';
+
+	if (value > 1000.0) {
+		value /= 1000.0;
+		*unit = 'K';
+	}
+
+	if (value > 1000.0) {
+		value /= 1000.0;
+		*unit = 'M';
+	}
+
+	if (value > 1000.0) {
+		value /= 1000.0;
+		*unit = 'G';
+	}
+
+	return value;
+}
+
+unsigned long convert_unit(unsigned long value, char *unit)
+{
+	double v = convert_unit_double((double)value, unit);
+
+	return (unsigned long)v;
+}
+
+int unit_number__scnprintf(char *buf, size_t size, u64 n)
+{
+	char unit[] = "BKMG";
+	int i = 0;
+
+	while (((n / 1024) > 1) && (i < 3)) {
+		n /= 1024;
+		i++;
+	}
+
+	return scnprintf(buf, size, "%" PRIu64 "%c", n, unit[i]);
+}