Commit 033a52d0 authored by Owen Rafferty's avatar Owen Rafferty Committed by Masahiro Yamada
Browse files

kbuild: rewrite check-local-export in sh/awk 



Remove the bash build dependency for those who otherwise do not
have it installed. This also provides a significant speedup:

$ make defconfig
$ make yes2modconfig

...

$ find  .  -name "*.o" | grep -v vmlinux | wc
     3169      3169     89615
$ export NM=nm
$ time sh -c 'find . -name "*.o" | grep -v vmlinux | xargs -n1
./scripts/check-local-export'

Without patch:
    0m15.90s real     0m12.17s user     0m05.28s system

With patch:
dash + nawk
    0m02.16s real     0m02.92s user     0m00.34s system

dash + busybox awk
    0m02.36s real     0m03.36s user     0m00.34s system

dash + gawk
    0m02.07s real     0m03.26s user     0m00.32s system

bash + gawk
    0m03.55s real     0m05.00s user     0m00.54s system

Signed-off-by: default avatarOwen Rafferty <owen@owenrafferty.com>
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
parent a6c26e38

scripts/check-local-export

+48 −49
Original line number Diff line number Diff line 
#!/usr/bin/env bash

#!/bin/sh

# SPDX-License-Identifier: GPL-2.0-only

#

# Copyright (C) 2022 Masahiro Yamada <masahiroy@kernel.org>

# Copyright (C) 2022 Owen Rafferty <owen@owenrafferty.com>

#

# Exit with error if a local exported symbol is found.

# EXPORT_SYMBOL should be used for global symbols.



set -e



# catch errors from ${NM}

set -o pipefail



# Run the last element of a pipeline in the current shell.

# Without this, the while-loop would be executed in a subshell, and

# the changes made to 'symbol_types' and 'export_symbols' would be lost.

shopt -s lastpipe



declare -A symbol_types

declare -a export_symbols



exit_code=0

pid=$$



# If there is no symbol in the object, ${NM} (both GNU nm and llvm-nm) shows

# 'no symbols' diagnostic (but exits with 0). It is harmless and hidden by
@@ -29,12 +18,15 @@ exit_code=0 
# TODO:

# Use --quiet instead of 2>/dev/null when we upgrade the minimum version of

# binutils to 2.37, llvm to 13.0.0.

# Then, the following line will be really simple:

#   ${NM} --quiet ${1} |

# Then, the following line will be simpler:

#   { ${NM} --quiet ${1} || kill 0; } |



{ ${NM} ${1} 2>/dev/null || { echo "${0}: ${NM} failed" >&2; kill $pid; } } |

${AWK} -v "file=${1}" '

BEGIN {

	i = 0

}



{ ${NM} ${1} 2>/dev/null || { echo "${0}: ${NM} failed" >&2; false; } } |

while read value type name

do

# Skip the line if the number of fields is less than 3.

#

# case 1)
@@ -44,28 +36,35 @@ do 
#   It is unneeded to record undefined symbols.

#

# case 2)

	#   For Clang LTO, llvm-nm outputs a line with type 't' but empty name:

#   For Clang LTO, llvm-nm outputs a line with type t but empty name:

#     "---------------- t"

	if [[ -z ${name} ]]; then

		continue

	fi

!length($3) {

	next

}



# save (name, type) in the associative array

	symbol_types[${name}]=${type}

{ symbol_types[$3]=$2 }



# append the exported symbol to the array

	if [[ ${name} == __ksymtab_* ]]; then

		export_symbols+=(${name#__ksymtab_})

	fi

done

($3 ~ /^__ksymtab_/) {

	export_symbols[i] = $3

	sub(/^__ksymtab_/, "", export_symbols[i])

	i++

}



for name in "${export_symbols[@]}"

do

END {

	exit_code = 0

	for (j = 0; j < i; ++j) {

		name = export_symbols[j]

		# nm(3) says "If lowercase, the symbol is usually local"

	if [[ ${symbol_types[$name]} =~ [a-z] ]]; then

		echo "$@: error: local symbol '${name}' was exported" >&2

		if (symbol_types[name] ~ /[a-z]/) {

			printf "%s: error: local symbol %s was exported\n",

				file, name | "cat 1>&2"

			exit_code = 1

	fi

done

		}

	}



	exit exit_code

}'



exit ${exit_code}
 
exit $?