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>

1 files changed, 29 insertions, 1 deletions

diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
index f7bab68..9c2ab06 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);
 }