[PATCH] kbuild: fix modpost segfault for 64bit mipsel kernel

Here is an updated r_info layout fix.  Please apply "check SHT_REL
sections" patch before this.

64bit mips has different r_info layout.  This patch fixes modpost
segfault for 64bit little endian mips kernel.
Signed-off-by: NAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

scripts/mod/modpost.c

@@ -700,6 +700,7 @@ static void check_sec_ref(struct module *mod, const char *modname,
 		const char *name = secstrings + sechdrs[i].sh_name;
 		const char *secname;
 		Elf_Rela r;
+		unsigned int r_sym;
 		/* We want to process only relocation sections and not .init */
 		if (sechdrs[i].sh_type == SHT_RELA) {
 			Elf_Rela *rela;
@@ -711,9 +712,20 @@ static void check_sec_ref(struct module *mod, const char *modname,
 
 			for (rela = start; rela < stop; rela++) {
 				r.r_offset = TO_NATIVE(rela->r_offset);
-				r.r_info   = TO_NATIVE(rela->r_info);
+#if KERNEL_ELFCLASS == ELFCLASS64
+				if (hdr->e_machine == EM_MIPS) {
+					r_sym = ELF64_MIPS_R_SYM(rela->r_info);
+					r_sym = TO_NATIVE(r_sym);
+				} else {
+					r.r_info = TO_NATIVE(rela->r_info);
+					r_sym = ELF_R_SYM(r.r_info);
+				}
+#else
+				r.r_info = TO_NATIVE(rela->r_info);
+				r_sym = ELF_R_SYM(r.r_info);
+#endif
 				r.r_addend = TO_NATIVE(rela->r_addend);
-				sym = elf->symtab_start + ELF_R_SYM(r.r_info);
+				sym = elf->symtab_start + r_sym;
 				/* Skip special sections */
 				if (sym->st_shndx >= SHN_LORESERVE)
 					continue;
@@ -734,9 +746,20 @@ static void check_sec_ref(struct module *mod, const char *modname,
 
 			for (rel = start; rel < stop; rel++) {
 				r.r_offset = TO_NATIVE(rel->r_offset);
-				r.r_info   = TO_NATIVE(rel->r_info);
+#if KERNEL_ELFCLASS == ELFCLASS64
+				if (hdr->e_machine == EM_MIPS) {
+					r_sym = ELF64_MIPS_R_SYM(rel->r_info);
+					r_sym = TO_NATIVE(r_sym);
+				} else {
+					r.r_info = TO_NATIVE(rel->r_info);
+					r_sym = ELF_R_SYM(r.r_info);
+				}
+#else
+				r.r_info = TO_NATIVE(rel->r_info);
+				r_sym = ELF_R_SYM(r.r_info);
+#endif
 				r.r_addend = 0;
-				sym = elf->symtab_start + ELF_R_SYM(r.r_info);
+				sym = elf->symtab_start + r_sym;
 				/* Skip special sections */
 				if (sym->st_shndx >= SHN_LORESERVE)
 					continue;

scripts/mod/modpost.h

@@ -41,6 +41,25 @@
 #define ELF_R_TYPE  ELF64_R_TYPE
 #endif
 
+/* The 64-bit MIPS ELF ABI uses an unusual reloc format. */
+typedef struct
+{
+	Elf32_Word    r_sym;	/* Symbol index */
+	unsigned char r_ssym;	/* Special symbol for 2nd relocation */
+	unsigned char r_type3;	/* 3rd relocation type */
+	unsigned char r_type2;	/* 2nd relocation type */
+	unsigned char r_type1;	/* 1st relocation type */
+} _Elf64_Mips_R_Info;
+
+typedef union
+{
+	Elf64_Xword		r_info_number;
+	_Elf64_Mips_R_Info	r_info_fields;
+} _Elf64_Mips_R_Info_union;
+
+#define ELF64_MIPS_R_SYM(i) \
+  ((__extension__ (_Elf64_Mips_R_Info_union)(i)).r_info_fields.r_sym)
+
 #if KERNEL_ELFDATA != HOST_ELFDATA
 
 static inline void __endian(const void *src, void *dest, unsigned int size)
@@ -50,8 +69,6 @@ static inline void __endian(const void *src, void *dest, unsigned int size)
 		((unsigned char*)dest)[i] = ((unsigned char*)src)[size - i-1];
 }
 
-
-
 #define TO_NATIVE(x)						\
 ({								\
 	typeof(x) __x;						\