linux - tools/objtool/tests/generic/test-data-alignment.sh

40 lines · 1.4 KiB

1	#!/bin/bash
2	# SPDX-License-Identifier: GPL-2.0
3	#
4	# A cloned data section keeps its alignment.
5	#
6	# Plenty of kernel data is aligned for correctness rather than speed: per-CPU
7	# variables, anything touched by an aligned vector move, structures padded to
8	# own a cacheline. A clone that lands under-aligned either faults on first use
9	# or silently shares a line it was laid out to avoid, and neither shows up
10	# until the patch is loaded on hardware that cares.
11	#
12	# Fixed by 2f2600decb30 ("objtool/klp: Fix alignment of cloned data
13	# sections").
14	#
15	# Covers the same ground as corpus/x86_64/cloned-data-alignment in Joe
16	# Lawrence's klp-build unit test corpus.
17
18	. "$(dirname "$0")/../lib.sh"
19
20	setup
21	build_pair data_alignment.c
22
23	# The premise: the compiler really did over-align it, and the object is new in
24	# the patch so it has to be cloned rather than referenced.
25	want="$(in_sections patched.o \| sed 's/^ \[[ 0-9]\] *//' \|
26	awk '$1 == ".data.aligned_data" { print $NF }')"
27	[ "$want" = 64 ] \|\|
28	probe_skip "compiler gave .data.aligned_data alignment '$want', not 64"
29	has_input_section orig.o .data.aligned_data &&
30	fail "fixture put aligned_data in the original; nothing to clone"
31
32	run_diff
33	assert_section .data.aligned_data
34
35	got="$(out_sections \| sed 's/^ \[[ 0-9]\] *//' \|
36	awk '$1 == ".data.aligned_data" { print $NF }')"
37	[ "$got" = "$want" ] \|\|
38	fail "cloned .data.aligned_data has alignment $got, expected $want"
39
40	pass "cloned data section keeps its alignment"