busybox/scripts/generate_BUFSIZ.sh
Denys Vlasenko 5b8c89d1f2 build system: make CONFIG_FEATURE_USE_BSS_TAIL less funky
CONFIG_FEATURE_USE_BSS_TAIL code was aliasing bb_common_bufsiz1 to _end.
This is unreliable: _end may be not sufficiently aligned.

Change code to simply enlarge COMMON_BUFSIZE when we detect that _end
has significant amount of space to the end of page.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2016-06-29 15:00:52 +02:00

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#!/bin/sh
# Called from top-level directory a-la
#
# scripts/generate_BUFSIZ.sh include/common_bufsiz.h
. ./.config || exit 1
debug=false
#debug=true
postcompile=false
test x"$1" = x"--post" && { postcompile=true; shift; }
common_bufsiz_h=$1
test x"$NM" = x"" && NM="${CONFIG_CROSS_COMPILER_PREFIX}nm"
test x"$CC" = x"" && CC="${CONFIG_CROSS_COMPILER_PREFIX}gcc"
exitcmd="exit 0"
regenerate() {
cat >"$1.$$"
test -f "$1" && diff "$1.$$" "$1" >/dev/null && rm "$1.$$" && return
mv "$1.$$" "$1"
}
generate_std_and_exit() {
$debug && echo "Configuring: bb_common_bufsiz1[] in bss"
{
echo "enum { COMMON_BUFSIZE = 1024 };"
echo "extern char bb_common_bufsiz1[];"
echo "#define setup_common_bufsiz() ((void)0)"
} | regenerate "$common_bufsiz_h"
echo "std" >"$common_bufsiz_h.method"
$exitcmd
}
generate_big_and_exit() {
$debug && echo "Configuring: bb_common_bufsiz1[] in bss, COMMON_BUFSIZE = $1"
{
echo "enum { COMMON_BUFSIZE = $1 };"
echo "extern char bb_common_bufsiz1[];"
echo "#define setup_common_bufsiz() ((void)0)"
} | regenerate "$common_bufsiz_h"
echo "$2" >"$common_bufsiz_h.method"
$exitcmd
}
generate_1k_and_exit() {
generate_big_and_exit 1024 "1k"
}
round_down_COMMON_BUFSIZE() {
COMMON_BUFSIZE=1024
test "$1" -le 32 && return
COMMON_BUFSIZE=$(( ($1-32) & 0x0ffffff0 ))
COMMON_BUFSIZE=$(( COMMON_BUFSIZE < 1024 ? 1024 : COMMON_BUFSIZE ))
}
# User does not want any funky stuff?
test x"$CONFIG_FEATURE_USE_BSS_TAIL" = x"y" || generate_std_and_exit
# The script is run two times: before compilation, when it needs to
# (re)generate $common_bufsiz_h, and directly after successful build,
# when it needs to assess whether the build is ok to use at all (not buggy),
# and (re)generate $common_bufsiz_h for a future build.
if $postcompile; then
# Postcompile needs to create/delete OK/FAIL files
test -f busybox_unstripped || exit 1
test -f "$common_bufsiz_h.method" || exit 1
# How the build was done?
method=`cat -- "$common_bufsiz_h.method"`
# Get _end address
END=`$NM busybox_unstripped | grep ' . _end$'| cut -d' ' -f1`
test x"$END" = x"" && generate_std_and_exit
$debug && echo "END:0x$END $((0x$END))"
END=$((0x$END))
# Get PAGE_SIZE
{
echo "#include <sys/user.h>"
echo "#if defined(PAGE_SIZE) && PAGE_SIZE > 0"
echo "char page_size[PAGE_SIZE];"
echo "#endif"
} >page_size_$$.c
$CC -c "page_size_$$.c" || exit 1
PAGE_SIZE=`$NM --size-sort "page_size_$$.o" | cut -d' ' -f1`
rm "page_size_$$.c" "page_size_$$.o"
test x"$PAGE_SIZE" = x"" && exit 1
$debug && echo "PAGE_SIZE:0x$PAGE_SIZE $((0x$PAGE_SIZE))"
PAGE_SIZE=$((0x$PAGE_SIZE))
test $PAGE_SIZE -lt 1024 && exit 1
# How much space between _end[] and next page?
PAGE_MASK=$((PAGE_SIZE-1))
TAIL_SIZE=$(( (-END) & PAGE_MASK ))
$debug && echo "TAIL_SIZE:$TAIL_SIZE bytes"
if test x"$method" = x"1k"; then
{
echo $TAIL_SIZE
md5sum <.config | cut -d' ' -f1
stat -c "%Y" .config
} >"$common_bufsiz_h.1k.OK"
round_down_COMMON_BUFSIZE $((1024 + TAIL_SIZE))
# emit message only if COMMON_BUFSIZE is indeed larger
test $COMMON_BUFSIZE -gt 1024 \
&& echo "Rerun make to use larger COMMON_BUFSIZE ($COMMON_BUFSIZE)"
test $COMMON_BUFSIZE = 1024 && generate_1k_and_exit
generate_big_and_exit $COMMON_BUFSIZE "big"
fi
fi
# Based on past success/fail of 1k build, decide next build type
if test -f "$common_bufsiz_h.1k.OK"; then
# previous 1k build succeeded
oldcfg=`tail -n2 -- "$common_bufsiz_h.1k.OK"`
curcfg=`md5sum <.config | cut -d' ' -f1; stat -c "%Y" .config`
# config did not change
if test x"$oldcfg" = x"$curcfg"; then
# Try bigger COMMON_BUFSIZE if possible
TAIL_SIZE=`head -n1 -- "$common_bufsiz_h.1k.OK"`
round_down_COMMON_BUFSIZE $((1024 + TAIL_SIZE))
test $COMMON_BUFSIZE = 1024 && generate_1k_and_exit
generate_big_and_exit $COMMON_BUFSIZE "big"
fi
# config did change
rm -rf -- "$common_bufsiz_h.1k.OK"
fi
# There was no 1k build yet. Try it.
generate_1k_and_exit