1#!/bin/sh
2# SPDX-License-Identifier: GPL-2.0-only
3#
4# Staring v4.18, Kconfig evaluates compiler capabilities, and hides CONFIG
5# options your compiler does not support. This works well if you configure and
6# build the kernel on the same host machine.
7#
8# It is inconvenient if you prepare the .config that is carried to a different
9# build environment (typically this happens when you package the kernel for
10# distros) because using a different compiler potentially produces different
11# CONFIG options than the real build environment. So, you probably want to make
12# as many options visible as possible. In other words, you need to create a
13# super-set of CONFIG options that cover any build environment. If some of the
14# CONFIG options turned out to be unsupported on the build machine, they are
15# automatically disabled by the nature of Kconfig.
16#
17# However, it is not feasible to get a full-featured compiler for every arch.
18# Hence these dummy toolchains to make all compiler tests pass.
19#
20# Usage:
21#
22# From the top directory of the source tree, run
23#
24#   $ make CROSS_COMPILE=scripts/dummy-tools/ oldconfig
25#
26# Most of compiler features are tested by cc-option, which simply checks the
27# exit code of $(CC). This script does nothing and just exits with 0 in most
28# cases. So, $(cc-option, ...) is evaluated as 'y'.
29#
30# This scripts caters to more checks; handle --version and pre-process __GNUC__
31# etc. to pretend to be GCC, and also do right things to satisfy some scripts.
32
33# Check if the first parameter appears in the rest. Succeeds if found.
34# This helper is useful if a particular option was passed to this script.
35# Typically used like this:
36#   arg_contain <word-you-are-searching-for> "$@"
37arg_contain ()
38{
39	search="$1"
40	shift
41
42	while [ $# -gt 0 ]
43	do
44		if [ "$search" = "$1" ]; then
45			return 0
46		fi
47		shift
48	done
49
50	return 1
51}
52
53# To set CONFIG_CC_IS_GCC=y
54if arg_contain --version "$@"; then
55	echo "gcc (scripts/dummy-tools/gcc)"
56	exit 0
57fi
58
59if arg_contain -E "$@"; then
60	# For scripts/cc-version.sh; This emulates GCC 20.0.0
61	if arg_contain - "$@"; then
62		sed -n '/^GCC/{s/__GNUC__/20/; s/__GNUC_MINOR__/0/; s/__GNUC_PATCHLEVEL__/0/; p;}; s/__LONG_DOUBLE_128__/1/ p'
63		exit 0
64	else
65		echo "no input files" >&2
66		exit 1
67	fi
68fi
69
70# To set CONFIG_AS_IS_GNU
71if arg_contain -Wa,--version "$@"; then
72	echo "GNU assembler (scripts/dummy-tools) 2.50"
73	exit 0
74fi
75
76if arg_contain -S "$@"; then
77	# For scripts/gcc-x86-*-has-stack-protector.sh
78	if arg_contain -fstack-protector "$@"; then
79		if arg_contain -mstack-protector-guard-reg=fs "$@"; then
80			echo "%fs"
81		else
82			echo "%gs"
83		fi
84		exit 0
85	fi
86
87	# For arch/powerpc/tools/gcc-check-mprofile-kernel.sh
88	if arg_contain -m64 "$@" && arg_contain -mprofile-kernel "$@"; then
89		if ! test -t 0 && ! grep -q notrace; then
90			echo "_mcount"
91		fi
92		exit 0
93	fi
94
95	# For arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh
96	if arg_contain -m64 "$@" && arg_contain -fpatchable-function-entry=2 "$@"; then
97		echo "func:"
98		echo ".section __patchable_function_entries"
99		echo ".localentry"
100		echo "  nop"
101		echo "  nop"
102		exit 0
103	fi
104fi
105
106# To set GCC_PLUGINS
107if arg_contain -print-file-name=plugin "$@"; then
108	# Use $0 to find the in-tree dummy directory
109	echo "$(dirname "$(readlink -f "$0")")/dummy-plugin-dir"
110	exit 0
111fi
112
113# inverted return value
114if arg_contain -D__SIZEOF_INT128__=0 "$@"; then
115	exit 1
116fi
117