From: Gao Long <gaolong@xxxxxxxxxxxxx>
When shell variable $LANG is set to anything like zh_CN.UTF-8,
there will be an error in mips kernel compiling, complaining about
unknown "invalid operands `dli $26'". It is because of retreiving
a bad "start address" from vmlinux, by using objdump -f vmlinux.
New tool has been added to linux kernel 5.4, named elf-entry,
to get correct "start address", regardless of the $LANG shell variable.
I back-ported the elf-entry tool and relevant Makefiles to 4.19.
Signed-off-by: Gao Long <gaolong@xxxxxxxxxxxxx>
---
arch/mips/Makefile | 8 +---
arch/mips/tools/Makefile | 5 +++
arch/mips/tools/elf-entry.c | 96 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 103 insertions(+), 6 deletions(-)
create mode 100644 arch/mips/tools/Makefile
create mode 100644 arch/mips/tools/elf-entry.c
diff --git a/arch/mips/Makefile b/arch/mips/Makefile
index ad0a92f..448397e 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -13,6 +13,7 @@
#
archscripts: scripts_basic
+ $(Q)$(MAKE) $(build)=arch/mips/tools elf-entry
$(Q)$(MAKE) $(build)=arch/mips/boot/tools relocs
KBUILD_DEFCONFIG := 32r2el_defconfig
@@ -259,12 +260,7 @@ load-y = $(CONFIG_PHYSICAL_START)
endif
# Sign-extend the entry point to 64 bits if retrieved as a 32-bit number.
-entry-y = $(shell $(OBJDUMP) -f vmlinux 2>/dev/null \
- | sed -n '/^start address / { \
- s/^.* //; \
- s/0x\([0-7].......\)$$/0x00000000\1/; \
- s/0x\(........\)$$/0xffffffff\1/; p }')
-
+entry-y = $(shell $(objtree)/arch/mips/tools/elf-entry vmlinux)
cflags-y += -I$(srctree)/arch/mips/include/asm/mach-generic
drivers-$(CONFIG_PCI) += arch/mips/pci/
diff --git a/arch/mips/tools/Makefile b/arch/mips/tools/Makefile
new file mode 100644
index 0000000..3baee4b
--- /dev/null
+++ b/arch/mips/tools/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+hostprogs-y := elf-entry
+PHONY += elf-entry
+elf-entry: $(obj)/elf-entry
+ @:
diff --git a/arch/mips/tools/elf-entry.c b/arch/mips/tools/elf-entry.c
new file mode 100644
index 0000000..adde79c
--- /dev/null
+++ b/arch/mips/tools/elf-entry.c
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <byteswap.h>
+#include <elf.h>
+#include <endian.h>
+#include <inttypes.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef be32toh
+/* If libc provides [bl]e{32,64}toh() then we'll use them */
+#elif BYTE_ORDER == LITTLE_ENDIAN
+# define be32toh(x) bswap_32(x)
+# define le32toh(x) (x)
+# define be64toh(x) bswap_64(x)
+# define le64toh(x) (x)
+#elif BYTE_ORDER == BIG_ENDIAN
+# define be32toh(x) (x)
+# define le32toh(x) bswap_32(x)
+# define be64toh(x) (x)
+# define le64toh(x) bswap_64(x)
+#endif
+
+__attribute__((noreturn))
+static void die(const char *msg)
+{
+ fputs(msg, stderr);
+ exit(EXIT_FAILURE);
+}
+
+int main(int argc, const char *argv[])
+{
+ uint64_t entry;
+ size_t nread;
+ FILE *file;
+ union {
+ Elf32_Ehdr ehdr32;
+ Elf64_Ehdr ehdr64;
+ } hdr;
+
+ if (argc != 2)
+ die("Usage: elf-entry <elf-file>\n");
+
+ file = fopen(argv[1], "r");
+ if (!file) {
+ perror("Unable to open input file");
+ return EXIT_FAILURE;
+ }
+
+ nread = fread(&hdr, 1, sizeof(hdr), file);
+ if (nread != sizeof(hdr)) {
+ perror("Unable to read input file");
+ return EXIT_FAILURE;
+ }
+
+ if (memcmp(hdr.ehdr32.e_ident, ELFMAG, SELFMAG))
+ die("Input is not an ELF\n");
+
+ switch (hdr.ehdr32.e_ident[EI_CLASS]) {
+ case ELFCLASS32:
+ switch (hdr.ehdr32.e_ident[EI_DATA]) {
+ case ELFDATA2LSB:
+ entry = le32toh(hdr.ehdr32.e_entry);
+ break;
+ case ELFDATA2MSB:
+ entry = be32toh(hdr.ehdr32.e_entry);
+ break;
+ default:
+ die("Invalid ELF encoding\n");
+ }
+
+ /* Sign extend to form a canonical address */
+ entry = (int64_t)(int32_t)entry;
+ break;
+
+ case ELFCLASS64:
+ switch (hdr.ehdr32.e_ident[EI_DATA]) {
+ case ELFDATA2LSB:
+ entry = le64toh(hdr.ehdr64.e_entry);
+ break;
+ case ELFDATA2MSB:
+ entry = be64toh(hdr.ehdr64.e_entry);
+ break;
+ default:
+ die("Invalid ELF encoding\n");
+ }
+ break;
+
+ default:
+ die("Invalid ELF class\n");
+ }
+
+ printf("0x%016" PRIx64 "\n", entry);
+ return EXIT_SUCCESS;
+}
--
2.7.4
