3 files changed, 58 insertions, 7 deletions

diff --git a/tools/include/nolibc/string.h b/tools/include/nolibc/string.h
index bef35bee9c44..ad97c0d522b8 100644
--- a/tools/include/nolibc/string.h
+++ b/tools/include/nolibc/string.h
@@ -19,9 +19,9 @@ static __attribute__((unused))
 int memcmp(const void *s1, const void *s2, size_t n)
 {
 	size_t ofs = 0;
-	char c1 = 0;
+	int c1 = 0;
 
-	while (ofs < n && !(c1 = ((char *)s1)[ofs] - ((char *)s2)[ofs])) {
+	while (ofs < n && !(c1 = ((unsigned char *)s1)[ofs] - ((unsigned char *)s2)[ofs])) {
 		ofs++;
 	}
 	return c1;
@@ -125,14 +125,18 @@ char *strcpy(char *dst, const char *src)
 }
 
 /* this function is only used with arguments that are not constants or when
- * it's not known because optimizations are disabled.
+ * it's not known because optimizations are disabled. Note that gcc 12
+ * recognizes an strlen() pattern and replaces it with a jump to strlen(),
+ * thus itself, hence the asm() statement below that's meant to disable this
+ * confusing practice.
  */
 static __attribute__((unused))
-size_t nolibc_strlen(const char *str)
+size_t strlen(const char *str)
 {
 	size_t len;
 
-	for (len = 0; str[len]; len++);
+	for (len = 0; str[len]; len++)
+		asm("");
 	return len;
 }
 
@@ -140,13 +144,12 @@ size_t nolibc_strlen(const char *str)
  * the two branches, then will rely on an external definition of strlen().
  */
 #if defined(__OPTIMIZE__)
+#define nolibc_strlen(x) strlen(x)
 #define strlen(str) ({                          \
 	__builtin_constant_p((str)) ?           \
 		__builtin_strlen((str)) :       \
 		nolibc_strlen((str));           \
 })
-#else
-#define strlen(str) nolibc_strlen((str))
 #endif
 
 static __attribute__((unused))
diff --git a/tools/include/uapi/linux/in.h b/tools/include/uapi/linux/in.h
index f243ce665f74..07a4cb149305 100644
--- a/tools/include/uapi/linux/in.h
+++ b/tools/include/uapi/linux/in.h
@@ -20,6 +20,7 @@
 #define _UAPI_LINUX_IN_H
 
 #include <linux/types.h>
+#include <linux/stddef.h>
 #include <linux/libc-compat.h>
 #include <linux/socket.h>
 
diff --git a/tools/include/uapi/linux/stddef.h b/tools/include/uapi/linux/stddef.h
new file mode 100644
index 000000000000..bb6ea517efb5
--- /dev/null
+++ b/tools/include/uapi/linux/stddef.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _LINUX_STDDEF_H
+#define _LINUX_STDDEF_H
+
+
+
+#ifndef __always_inline
+#define __always_inline __inline__
+#endif
+
+/**
+ * __struct_group() - Create a mirrored named and anonyomous struct
+ *
+ * @TAG: The tag name for the named sub-struct (usually empty)
+ * @NAME: The identifier name of the mirrored sub-struct
+ * @ATTRS: Any struct attributes (usually empty)
+ * @MEMBERS: The member declarations for the mirrored structs
+ *
+ * Used to create an anonymous union of two structs with identical layout
+ * and size: one anonymous and one named. The former's members can be used
+ * normally without sub-struct naming, and the latter can be used to
+ * reason about the start, end, and size of the group of struct members.
+ * The named struct can also be explicitly tagged for layer reuse, as well
+ * as both having struct attributes appended.
+ */
+#define __struct_group(TAG, NAME, ATTRS, MEMBERS...) \
+	union { \
+		struct { MEMBERS } ATTRS; \
+		struct TAG { MEMBERS } ATTRS NAME; \
+	}
+
+/**
+ * __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union
+ *
+ * @TYPE: The type of each flexible array element
+ * @NAME: The name of the flexible array member
+ *
+ * In order to have a flexible array member in a union or alone in a
+ * struct, it needs to be wrapped in an anonymous struct with at least 1
+ * named member, but that member can be empty.
+ */
+#define __DECLARE_FLEX_ARRAY(TYPE, NAME)	\
+	struct { \
+		struct { } __empty_ ## NAME; \
+		TYPE NAME[]; \
+	}
+#endif