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