Running objtool klp-diff on a changed function which uses WARN() can
fail with:
vmlinux.o: error: objtool: md_run+0x866: failed to convert reloc sym
'__bug_table' to its proper format
The problem is that since commit 5b472b6e5bd9 ("x86_64/bug: Implement
__WARN_printf()"), each __WARN_printf() call site now directly
references its bug table entry. klp-diff errors out when it can't
convert such section-based references to object symbols (because bug
table entries don't have symbols).
Luckily, klp-diff already has code to create symbols for bug table
entries. Move that code earlier, before function diffing.
Fixes: dd590d4d57eb ("objtool/klp: Introduce klp diff subcommand for diffing
object files")
Fixes: 5b472b6e5bd9 ("x86_64/bug: Implement __WARN_printf()")
Reported-by: Song Liu <[email protected]>
Signed-off-by: Josh Poimboeuf <[email protected]>
---
For tip/objtool/urgent.
tools/objtool/klp-diff.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
index bb6b711d4e73..76aa77c26655 100644
--- a/tools/objtool/klp-diff.c
+++ b/tools/objtool/klp-diff.c
@@ -1425,9 +1425,6 @@ static int clone_special_sections(struct elfs *e)
{
struct section *patched_sec;
- if (create_fake_symbols(e->patched))
- return -1;
-
for_each_sec(e->patched, patched_sec) {
if (is_special_section(patched_sec)) {
if (clone_special_section(e, patched_sec))
@@ -1704,6 +1701,17 @@ int cmd_klp_diff(int argc, const char **argv)
if (!e.out)
return -1;
+ /*
+ * Special section fake symbols are needed so that individual special
+ * section entries can be extracted by clone_special_sections().
+ *
+ * Note the fake symbols are also needed by clone_included_functions()
+ * because __WARN_printf() call sites add references to bug table
+ * entries in the calling functions.
+ */
+ if (create_fake_symbols(e.patched))
+ return -1;
+
if (clone_included_functions(&e))
return -1;
--
2.52.0
