linux - tools/objtool/tests/generic/test-cold-function.sh

39 lines · 1.6 KiB

1	#!/bin/bash
2	# SPDX-License-Identifier: GPL-2.0
3	#
4	# Both halves of a split function belong to the patch; carrying only the hot
5	# part leaves the cold path branching into unpatched code.
6
7	. "$(dirname "$0")/../lib.sh"
8
9	# Clang does not split functions into a cold part at all, so there is nothing
10	# for this test to look at there. A given gcc may or may not split, which is a
11	# version property rather than a compiler choice -- that stays a probe below.
12	gcc_only "clang does not split functions into a cold part"
13
14	setup
15
16	split_flag=-freorder-blocks-and-partition
17	cc_supports "$split_flag" \|\| split_flag=
18
19	build_pair cold_function.c $split_flag
20
21	# Find what the compiler called the cold half -- target.cold, target.cold.0,
22	# depending on version -- and name it exactly from here on.
23	cold_sym="$(in_symbols orig.o \| awk '$NF ~ /^target\.cold/ { print $NF; exit }')"
24	[ -n "$cold_sym" ] \|\|
25	probe_skip "compiler did not split the function into a cold part"
26
27	run_diff
28
29	assert_patched target
30	# Match the name field exactly, and require it to be defined. Had the cold
31	# half been left behind, the branch to it would appear as an undefined
32	# .klp.sym.vmlinux.target.cold,0 -- a different name, which happens to contain
33	# this one. Asking about a column instead of the name would not tell them
34	# apart: readelf prints SHN_LIVEPATCH as "OS [0xff20]" and llvm-readelf as
35	# "OS[0xff20]", so the fields either side of the name shift between the two.
36	out_symbols \| awk -v n="$cold_sym" '$NF == n && $(NF - 1) != "UND"' \| grep -q . \|\|
37	fail "cold half ($cold_sym) was not carried into the patch"
38
39	pass "cold half carried into the patch with its parent"