x86, relocs: Add manual debug mode

Improve the debuggability of relocations output. When trying to compare
the output between different linkers, it's handy to be able to see the
section names in output.

Signed-off-by: Michael Davidson <md@google.com>
Link: http://lkml.kernel.org/r/20140121203223.GA12649@www.outflux.net
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

3 files changed, 45 insertions, 8 deletions

diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
index f7bab68a4b83..9c2ab06dc4f2 100644
--- a/arch/x86/tools/relocs.c
+++ b/arch/x86/tools/relocs.c
@@ -1015,6 +1015,29 @@ static void emit_relocs(int as_text, int use_real_mode)
         }
 }
 
+/*
+ * As an aid to debugging problems with different linkers
+ * print summary information about the relocs.
+ * Since different linkers tend to emit the sections in
+ * different orders we use the section names in the output.
+ */
+static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
+                                const char *symname)
+{
+        printf("%s\t%s\t%s\t%s\n",
+                sec_name(sec->shdr.sh_info),
+                rel_type(ELF_R_TYPE(rel->r_info)),
+                symname,
+                sec_name(sym->st_shndx));
+        return 0;
+}
+
+static void print_reloc_info(void)
+{
+        printf("reloc section\treloc type\tsymbol\tsymbol section\n");
+        walk_relocs(do_reloc_info);
+}
+
 #if ELF_BITS == 64
 # define process process_64
 #else
@@ -1022,7 +1045,8 @@ static void emit_relocs(int as_text, int use_real_mode)
 #endif
 
 void process(FILE *fp, int use_real_mode, int as_text,
-             int show_absolute_syms, int show_absolute_relocs)
+             int show_absolute_syms, int show_absolute_relocs,
+             int show_reloc_info)
 {
         regex_init(use_real_mode);
         read_ehdr(fp);
@@ -1040,5 +1064,9 @@ void process(FILE *fp, int use_real_mode, int as_text,
                 print_absolute_relocs();
                 return;
         }
+        if (show_reloc_info) {
+                print_reloc_info();
+                return;
+        }
         emit_relocs(as_text, use_real_mode);
 }
diff --git a/arch/x86/tools/relocs.h b/arch/x86/tools/relocs.h
index 07cdb1eca4fa..f59590645b68 100644
--- a/arch/x86/tools/relocs.h
+++ b/arch/x86/tools/relocs.h
@@ -29,8 +29,9 @@ enum symtype {
 };
 
 void process_32(FILE *fp, int use_real_mode, int as_text,
-                int show_absolute_syms, int show_absolute_relocs);
+                int show_absolute_syms, int show_absolute_relocs,
+                int show_reloc_info);
 void process_64(FILE *fp, int use_real_mode, int as_text,
-                int show_absolute_syms, int show_absolute_relocs);
-
+                int show_absolute_syms, int show_absolute_relocs,
+                int show_reloc_info);
 #endif /* RELOCS_H */
diff --git a/arch/x86/tools/relocs_common.c b/arch/x86/tools/relocs_common.c
index 44d396823a53..acab636bcb34 100644
--- a/arch/x86/tools/relocs_common.c
+++ b/arch/x86/tools/relocs_common.c
@@ -11,12 +11,13 @@ void die(char *fmt, ...)
 
 static void usage(void)
 {
-        die("relocs [--abs-syms|--abs-relocs|--text|--realmode] vmlinux\n");
+        die("relocs [--abs-syms|--abs-relocs|--reloc-info|--text|--realmode]" \
+            " vmlinux\n");
 }
 
 int main(int argc, char **argv)
 {
-        int show_absolute_syms, show_absolute_relocs;
+        int show_absolute_syms, show_absolute_relocs, show_reloc_info;
         int as_text, use_real_mode;
         const char *fname;
         FILE *fp;
@@ -25,6 +26,7 @@ int main(int argc, char **argv)
 
         show_absolute_syms = 0;
         show_absolute_relocs = 0;
+        show_reloc_info = 0;
         as_text = 0;
         use_real_mode = 0;
         fname = NULL;
@@ -39,6 +41,10 @@ int main(int argc, char **argv)
                                 show_absolute_relocs = 1;
                                 continue;
                         }
+                        if (strcmp(arg, "--reloc-info") == 0) {
+                                show_reloc_info = 1;
+                                continue;
+                        }
                         if (strcmp(arg, "--text") == 0) {
                                 as_text = 1;
                                 continue;
@@ -67,10 +73,12 @@ int main(int argc, char **argv)
         rewind(fp);
         if (e_ident[EI_CLASS] == ELFCLASS64)
                 process_64(fp, use_real_mode, as_text,
-                           show_absolute_syms, show_absolute_relocs);
+                           show_absolute_syms, show_absolute_relocs,
+                           show_reloc_info);
         else
                 process_32(fp, use_real_mode, as_text,
-                           show_absolute_syms, show_absolute_relocs);
+                           show_absolute_syms, show_absolute_relocs,
+                           show_reloc_info);
         fclose(fp);
         return 0;
 }