linux - tools/objtool/tests/generic/test-new-export-ref.sh

46 lines · 1.8 KiB

1	#!/bin/bash
2	# SPDX-License-Identifier: GPL-2.0
3	#
4	# A reference the patch adds has no counterpart in the original object. klp
5	# diff used to reject any such reference needing a klp relocation, which ruled
6	# out patches that call something they did not call before -- a common enough
7	# thing for a fix to do.
8	#
9	# Module.symvers is what makes it safe: it says the symbol exists and who owns
10	# it. But that is only sufficient for a vmlinux export. A new reference to a
11	# module's export is a dependency the patch module does not declare, and the
12	# relocation would resolve only if that module happened to be loaded, so it
13	# stays an error.
14
15	. "$(dirname "$0")/../lib.sh"
16
17	setup
18	build_pair new_export_ref.c
19
20	# Exported by vmlinux, in a module: namespace so it needs a klp relocation
21	# rather than an ordinary one. Allowed.
22	export_syms
23	add_exports_ns vmlinux module:kvm newly_referenced
24	run_diff
25	assert_klp_sym newly_referenced vmlinux
26
27	# Exported by a module the patched object does not depend on. Rejected, and
28	# for that reason rather than some other.
29	export_syms
30	add_exports other_mod newly_referenced
31	run_diff 255
32	assert_diff_log 'undeclared module dependency'
33
34	# ... unless the original already referenced something that module exports.
35	# The loader will not let the patched object load without other_mod, so the
36	# klp relocation has something to resolve against, and klp diff allows it.
37	# This is the other half of the rule, and it fails in the opposite direction:
38	# refusing here would reject a patch which is safe to apply.
39	rm -f "$workdir/out.o"
40	build_pair new_export_ref.c -DEXISTING_DEP
41	export_syms
42	add_exports other_mod newly_referenced existing_dep
43	run_diff
44	assert_klp_sym newly_referenced other_mod
45
46	pass "new reference allowed for vmlinux and for a module already depended on"