From 31cb50b5590fe911077b8463ad01144fac8fa4f3 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Fri, 27 May 2022 19:01:51 +0900 Subject: kbuild: check static EXPORT_SYMBOL* by script instead of modpost The 'static' specifier and EXPORT_SYMBOL() are an odd combination. Commit 15bfc2348d54 ("modpost: check for static EXPORT_SYMBOL* functions") tried to detect it, but this check has false negatives. Here is the sample code. Makefile: obj-y += foo1.o foo2.o foo1.c: #include static void foo(void) {} EXPORT_SYMBOL(foo); foo2.c: void foo(void) {} foo1.c exports the static symbol 'foo', but modpost cannot catch it because it is fooled by foo2.c, which has a global symbol with the same name. s->is_static is cleared if a global symbol with the same name is found somewhere, but EXPORT_SYMBOL() and the global symbol do not necessarily belong to the same compilation unit. This check should be done per compilation unit, but I do not know how to do it in modpost. modpost runs against vmlinux.o or modules, which merges multiple objects, then forgets their origin. modpost cannot parse individual objects because they may not be ELF but LLVM IR when CONFIG_LTO_CLANG=y. Add a simple bash script to parse the output from ${NM}. This works for CONFIG_LTO_CLANG=y because llvm-nm can dump symbols of LLVM IR files. Revert 15bfc2348d54. Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers Tested-by: Nathan Chancellor Tested-by: Sedat Dilek # LLVM-14 (x86-64) --- scripts/check-local-export | 65 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100755 scripts/check-local-export (limited to 'scripts/check-local-export') diff --git a/scripts/check-local-export b/scripts/check-local-export new file mode 100755 index 000000000000..2c46912be0ef --- /dev/null +++ b/scripts/check-local-export @@ -0,0 +1,65 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0-only +# +# Copyright (C) 2022 Masahiro Yamada +# +# Exit with error if a local exported symbol is found. +# EXPORT_SYMBOL should be used for global symbols. + +set -e + +declare -A symbol_types +declare -a export_symbols + +exit_code=0 + +while read value type name +do + # Skip the line if the number of fields is less than 3. + # + # case 1) + # For undefined symbols, the first field (value) is empty. + # The outout looks like this: + # " U _printk" + # It is unneeded to record undefined symbols. + # + # case 2) + # For Clang LTO, llvm-nm outputs a line with type 't' but empty name: + # "---------------- t" + if [[ -z ${name} ]]; then + continue + fi + + # save (name, type) in the associative array + symbol_types[${name}]=${type} + + # append the exported symbol to the array + if [[ ${name} == __ksymtab_* ]]; then + export_symbols+=(${name#__ksymtab_}) + fi + + # If there is no symbol in the object, ${NM} (both GNU nm and llvm-nm) + # shows 'no symbols' diagnostic (but exits with 0). It is harmless and + # hidden by '2>/dev/null'. However, it suppresses real error messages + # as well. Add a hand-crafted error message here. + # + # Use --quiet instead of 2>/dev/null when we upgrade the minimum version + # of binutils to 2.37, llvm to 13.0.0. + # + # Then, the following line will be really simple: + # done < <(${NM} --quiet ${1}) +done < <(${NM} ${1} 2>/dev/null || { echo "${0}: ${NM} failed" >&2; false; } ) + +# Catch error in the process substitution +wait $! + +for name in "${export_symbols[@]}" +do + # 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 + exit_code=1 + fi +done + +exit ${exit_code} -- cgit From 42ce60aa5aa46ae00f71aa806a11510b6db6d1a7 Mon Sep 17 00:00:00 2001 From: Schspa Shi Date: Fri, 3 Jun 2022 17:38:52 +0800 Subject: kbuild: Allow to select bash in a modified environment This fixes the build error when the system has a default bash version which is too old to support associative array variables. The build error log as fellowing: linux/scripts/check-local-export: line 11: declare: -A: invalid option declare: usage: declare [-afFirtx] [-p] [name[=value] ...] Signed-off-by: Schspa Shi Signed-off-by: Masahiro Yamada --- scripts/check-local-export | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts/check-local-export') diff --git a/scripts/check-local-export b/scripts/check-local-export index 2c46912be0ef..da745e2743b7 100755 --- a/scripts/check-local-export +++ b/scripts/check-local-export @@ -1,4 +1,4 @@ -#!/bin/bash +#!/usr/bin/env bash # SPDX-License-Identifier: GPL-2.0-only # # Copyright (C) 2022 Masahiro Yamada -- cgit From da4288b95baa1c7c9aa8a476f58b37eb238745b0 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Wed, 8 Jun 2022 10:11:00 +0900 Subject: scripts/check-local-export: avoid 'wait $!' for process substitution Bash 4.4, released in 2016, supports 'wait $!' to check the exit status of a process substitution, but it seems too new. Some people using older bash versions (on CentOS 7, Ubuntu 16.04, etc.) reported an error like this: ./scripts/check-local-export: line 54: wait: pid 17328 is not a child of this shell I used the process substitution to avoid a pipeline, which executes each command in a subshell. If the while-loop is executed in the subshell context, variable changes within are lost after the subshell terminates. Fortunately, Bash 4.2, released in 2011, supports the 'lastpipe' option, which makes the last element of a pipeline run in the current shell process. Switch to the pipeline with 'lastpipe' solution, and also set 'pipefail' to catch errors from ${NM}. Add the bash requirement to Documentation/process/changes.rst. Fixes: 31cb50b5590f ("kbuild: check static EXPORT_SYMBOL* by script instead of modpost") Reported-by: Tetsuo Handa Reported-by: Michael Ellerman Reported-by: Wang Yugui Tested-by: Tetsuo Handa Tested-by: Jon Hunter Acked-by: Nick Desaulniers Tested-by: Sedat Dilek # LLVM-14 (x86-64) Signed-off-by: Masahiro Yamada --- scripts/check-local-export | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-) (limited to 'scripts/check-local-export') diff --git a/scripts/check-local-export b/scripts/check-local-export index da745e2743b7..6ccc2f467416 100755 --- a/scripts/check-local-export +++ b/scripts/check-local-export @@ -8,11 +8,31 @@ 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 +# 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 +# '2>/dev/null'. However, it suppresses real error messages as well. Add a +# hand-crafted error message here. +# +# 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} | + +{ ${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. @@ -37,21 +57,7 @@ do if [[ ${name} == __ksymtab_* ]]; then export_symbols+=(${name#__ksymtab_}) fi - - # If there is no symbol in the object, ${NM} (both GNU nm and llvm-nm) - # shows 'no symbols' diagnostic (but exits with 0). It is harmless and - # hidden by '2>/dev/null'. However, it suppresses real error messages - # as well. Add a hand-crafted error message here. - # - # Use --quiet instead of 2>/dev/null when we upgrade the minimum version - # of binutils to 2.37, llvm to 13.0.0. - # - # Then, the following line will be really simple: - # done < <(${NM} --quiet ${1}) -done < <(${NM} ${1} 2>/dev/null || { echo "${0}: ${NM} failed" >&2; false; } ) - -# Catch error in the process substitution -wait $! +done for name in "${export_symbols[@]}" do -- cgit From 033a52d033607dab1c9b93962921dc6a9a9146b3 Mon Sep 17 00:00:00 2001 From: Owen Rafferty Date: Wed, 31 Aug 2022 15:57:08 -0500 Subject: 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: Owen Rafferty Signed-off-by: Masahiro Yamada --- scripts/check-local-export | 97 +++++++++++++++++++++++----------------------- 1 file changed, 48 insertions(+), 49 deletions(-) (limited to 'scripts/check-local-export') diff --git a/scripts/check-local-export b/scripts/check-local-export index 6ccc2f467416..f90b5a9c67b3 100755 --- a/scripts/check-local-export +++ b/scripts/check-local-export @@ -1,25 +1,14 @@ -#!/usr/bin/env bash +#!/bin/sh # SPDX-License-Identifier: GPL-2.0-only # # Copyright (C) 2022 Masahiro Yamada +# Copyright (C) 2022 Owen Rafferty # # 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 @@ -29,43 +18,53 @@ 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 +} + +# Skip the line if the number of fields is less than 3. +# +# case 1) +# For undefined symbols, the first field (value) is empty. +# The outout looks like this: +# " U _printk" +# It is unneeded to record undefined symbols. +# +# case 2) +# For Clang LTO, llvm-nm outputs a line with type t but empty name: +# "---------------- t" +!length($3) { + next +} -{ ${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) - # For undefined symbols, the first field (value) is empty. - # The outout looks like this: - # " U _printk" - # It is unneeded to record undefined symbols. - # - # case 2) - # For Clang LTO, llvm-nm outputs a line with type 't' but empty name: - # "---------------- t" - if [[ -z ${name} ]]; then - continue - fi +# save (name, type) in the associative array +{ symbol_types[$3]=$2 } - # save (name, type) in the associative array - symbol_types[${name}]=${type} +# append the exported symbol to the array +($3 ~ /^__ksymtab_/) { + export_symbols[i] = $3 + sub(/^__ksymtab_/, "", export_symbols[i]) + i++ +} - # append the exported symbol to the array - if [[ ${name} == __ksymtab_* ]]; then - export_symbols+=(${name#__ksymtab_}) - fi -done +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]/) { + printf "%s: error: local symbol %s was exported\n", + file, name | "cat 1>&2" + exit_code = 1 + } + } -for name in "${export_symbols[@]}" -do - # 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 - exit_code=1 - fi -done + exit exit_code +}' -exit ${exit_code} +exit $? -- cgit