The current TO_NATIVE() has some limitations:
1) You cannot cast the argument.
2) You cannot pass a variable marked as 'const'.
3) Passing an array is a bug, but it is not detected.
Impelement TO_NATIVE() using bswap_*() functions. These are GNU
extensions. If we face portability issues, we can port the code from
include/uapi/linux/swab.h.
With this change, get_rel_type_and_sym() can be simplified by casting
the arguments directly.
Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
---
scripts/mod/modpost.c | 13 ++++---------
scripts/mod/modpost.h | 25 ++++++++++++-------------
2 files changed, 16 insertions(+), 22 deletions(-)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 2f3b0fe6f68d..99476a9695c5 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1410,15 +1410,10 @@ static void get_rel_type_and_sym(struct elf_info *elf, uint64_t r_info,
return;
}
- if (is_64bit) {
- Elf64_Xword r_info64 = r_info;
-
- r_info = TO_NATIVE(r_info64);
- } else {
- Elf32_Word r_info32 = r_info;
-
- r_info = TO_NATIVE(r_info32);
- }
+ if (is_64bit)
+ r_info = TO_NATIVE((Elf64_Xword)r_info);
+ else
+ r_info = TO_NATIVE((Elf32_Word)r_info);
*r_type = ELF_R_TYPE(r_info);
*r_sym = ELF_R_SYM(r_info);
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index 6413f26fcb6b..1392afec118c 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -1,4 +1,5 @@
/* SPDX-License-Identifier: GPL-2.0 */
+#include <byteswap.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
@@ -51,21 +52,19 @@
#define ELF_R_TYPE ELF64_R_TYPE
#endif
+#define bswap(x) \
+({ \
+ _Static_assert(sizeof(x) == 1 || sizeof(x) == 2 || \
+ sizeof(x) == 4 || sizeof(x) == 8, "bug"); \
+ (typeof(x))(sizeof(x) == 2 ? bswap_16(x) : \
+ sizeof(x) == 4 ? bswap_32(x) : \
+ sizeof(x) == 8 ? bswap_64(x) : \
+ x); \
+})
+
#if KERNEL_ELFDATA != HOST_ELFDATA
-static inline void __endian(const void *src, void *dest, unsigned int size)
-{
- unsigned int i;
- for (i = 0; i < size; i++)
- ((unsigned char*)dest)[i] = ((unsigned char*)src)[size - i-1];
-}
-
-#define TO_NATIVE(x) \
-({ \
- typeof(x) __x; \
- __endian(&(x), &(__x), sizeof(__x)); \
- __x; \
-})
+#define TO_NATIVE(x) (bswap(x))
#else /* endianness matches */
--
2.39.2
