diff options
| -rw-r--r-- | arch/i386/boot/compressed/Makefile | 2 | ||||
| -rw-r--r-- | arch/i386/boot/compressed/relocs.c | 82 |
2 files changed, 73 insertions, 11 deletions
diff --git a/arch/i386/boot/compressed/Makefile b/arch/i386/boot/compressed/Makefile index cc28da3a881..a661217f33e 100644 --- a/arch/i386/boot/compressed/Makefile +++ b/arch/i386/boot/compressed/Makefile @@ -20,7 +20,7 @@ $(obj)/vmlinux.bin: vmlinux FORCE $(call if_changed,objcopy) quiet_cmd_relocs = RELOCS $@ - cmd_relocs = $(obj)/relocs $< > $@ + cmd_relocs = $(obj)/relocs $< > $@;$(obj)/relocs --abs-relocs $< $(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE $(call if_changed,relocs) diff --git a/arch/i386/boot/compressed/relocs.c b/arch/i386/boot/compressed/relocs.c index 0551ceb21be..468da89153c 100644 --- a/arch/i386/boot/compressed/relocs.c +++ b/arch/i386/boot/compressed/relocs.c @@ -19,6 +19,33 @@ static char *strtab[MAX_SHDRS]; static unsigned long reloc_count, reloc_idx; static unsigned long *relocs; +/* + * Following symbols have been audited. There values are constant and do + * not change if bzImage is loaded at a different physical address than + * the address for which it has been compiled. Don't warn user about + * absolute relocations present w.r.t these symbols. + */ +static const char* safe_abs_relocs[] = { + "__kernel_vsyscall", + "__kernel_rt_sigreturn", + "__kernel_sigreturn", + "SYSENTER_RETURN", +}; + +static int is_safe_abs_reloc(const char* sym_name) +{ + int i, array_size; + + array_size = sizeof(safe_abs_relocs)/sizeof(char*); + + for(i = 0; i < array_size; i++) { + if (!strcmp(sym_name, safe_abs_relocs[i])) + /* Match found */ + return 1; + } + return 0; +} + static void die(char *fmt, ...) { va_list ap; @@ -359,9 +386,8 @@ static void print_absolute_symbols(void) static void print_absolute_relocs(void) { - int i; - printf("Absolute relocations\n"); - printf("Offset Info Type Sym.Value Sym.Name\n"); + int i, printed = 0; + for(i = 0; i < ehdr.e_shnum; i++) { char *sym_strtab; Elf32_Sym *sh_symtab; @@ -387,6 +413,31 @@ static void print_absolute_relocs(void) if (sym->st_shndx != SHN_ABS) { continue; } + + /* Absolute symbols are not relocated if bzImage is + * loaded at a non-compiled address. Display a warning + * to user at compile time about the absolute + * relocations present. + * + * User need to audit the code to make sure + * some symbols which should have been section + * relative have not become absolute because of some + * linker optimization or wrong programming usage. + * + * Before warning check if this absolute symbol + * relocation is harmless. + */ + if (is_safe_abs_reloc(name)) + continue; + + if (!printed) { + printf("WARNING: Absolute relocations" + " present\n"); + printf("Offset Info Type Sym.Value " + "Sym.Name\n"); + printed = 1; + } + printf("%08x %08x %10s %08x %s\n", rel->r_offset, rel->r_info, @@ -395,7 +446,9 @@ static void print_absolute_relocs(void) name); } } - printf("\n"); + + if (printed) + printf("\n"); } static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym)) @@ -508,25 +561,31 @@ static void emit_relocs(int as_text) static void usage(void) { - die("i386_reloc [--abs | --text] vmlinux\n"); + die("relocs [--abs-syms |--abs-relocs | --text] vmlinux\n"); } int main(int argc, char **argv) { - int show_absolute; + int show_absolute_syms, show_absolute_relocs; int as_text; const char *fname; FILE *fp; int i; - show_absolute = 0; + show_absolute_syms = 0; + show_absolute_relocs = 0; as_text = 0; fname = NULL; for(i = 1; i < argc; i++) { char *arg = argv[i]; if (*arg == '-') { - if (strcmp(argv[1], "--abs") == 0) { - show_absolute = 1; + if (strcmp(argv[1], "--abs-syms") == 0) { + show_absolute_syms = 1; + continue; + } + + if (strcmp(argv[1], "--abs-relocs") == 0) { + show_absolute_relocs = 1; continue; } else if (strcmp(argv[1], "--text") == 0) { @@ -553,8 +612,11 @@ int main(int argc, char **argv) read_strtabs(fp); read_symtabs(fp); read_relocs(fp); - if (show_absolute) { + if (show_absolute_syms) { print_absolute_symbols(); + return 0; + } + if (show_absolute_relocs) { print_absolute_relocs(); return 0; } |