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Subject[PATCH] x86, relocs: add manual debug mode
From: Michael Davidson <md@google.com>

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>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
arch/x86/tools/relocs.c | 30 +++++++++++++++++++++++++++++-
arch/x86/tools/relocs.h | 7 ++++---
arch/x86/tools/relocs_common.c | 16 ++++++++++++----
3 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
index 11f9285a2ff6..cfbdbdb4e173 100644
--- a/arch/x86/tools/relocs.c
+++ b/arch/x86/tools/relocs.c
@@ -1025,6 +1025,29 @@ 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
@@ -1032,7 +1055,8 @@ 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);
@@ -1050,5 +1074,9 @@ 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;
}
--
1.7.9.5

--
Kees Cook
Chrome OS Security


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