[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: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 46 insertions, 6 deletions

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 1aa52a86c2c..d0f86ed43f7 100644
--- a/scripts/mod/modpost.c
+++ b/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;
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index 086fa466504..861d866fcd8 100644
--- a/scripts/mod/modpost.h
+++ b/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;                                          \