From 5b8c89d1f270909d1a0201478236de6ed89c8ca4 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Wed, 29 Jun 2016 15:00:52 +0200 Subject: [PATCH] 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 --- scripts/generate_BUFSIZ.sh | 100 +++++++++++-------------------------- 1 file changed, 28 insertions(+), 72 deletions(-) diff --git a/scripts/generate_BUFSIZ.sh b/scripts/generate_BUFSIZ.sh index 844261906..718788e0b 100755 --- a/scripts/generate_BUFSIZ.sh +++ b/scripts/generate_BUFSIZ.sh @@ -36,11 +36,10 @@ generate_std_and_exit() { } generate_big_and_exit() { - $debug && echo "Configuring: bb_common_bufsiz1[] in _end[], COMMON_BUFSIZE = $1" + $debug && echo "Configuring: bb_common_bufsiz1[] in bss, COMMON_BUFSIZE = $1" { echo "enum { COMMON_BUFSIZE = $1 };" - echo "extern char _end[]; /* linker-provided label */" - echo "#define bb_common_bufsiz1 _end" + echo "extern char bb_common_bufsiz1[];" echo "#define setup_common_bufsiz() ((void)0)" } | regenerate "$common_bufsiz_h" echo "$2" >"$common_bufsiz_h.method" @@ -51,20 +50,10 @@ generate_1k_and_exit() { generate_big_and_exit 1024 "1k" } - -generate_malloc_and_exit() { - $debug && echo "Configuring: bb_common_bufsiz1[] is malloced" - { - echo "enum { COMMON_BUFSIZE = 1024 };" - echo "extern char *const bb_common_bufsiz1;" - echo "void setup_common_bufsiz(void);" - } | regenerate "$common_bufsiz_h" - echo "malloc" >"$common_bufsiz_h.method" - $exitcmd -} - round_down_COMMON_BUFSIZE() { - COMMON_BUFSIZE=$(( ($1-32) & 0xfffffe0 )) + COMMON_BUFSIZE=1024 + test "$1" -le 32 && return + COMMON_BUFSIZE=$(( ($1-32) & 0x0ffffff0 )) COMMON_BUFSIZE=$(( COMMON_BUFSIZE < 1024 ? 1024 : COMMON_BUFSIZE )) } @@ -104,77 +93,44 @@ if $postcompile; then test x"$PAGE_SIZE" = x"" && exit 1 $debug && echo "PAGE_SIZE:0x$PAGE_SIZE $((0x$PAGE_SIZE))" PAGE_SIZE=$((0x$PAGE_SIZE)) - test $PAGE_SIZE -lt 512 && exit 1 + 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"$method" = x"1k" || test x"$method" = x"big"; then - if test $TAIL_SIZE -lt 1024; then - # _end[] has no enough space for bb_common_bufsiz1[] - echo "Warning! Space in _end[] is too small ($TAIL_SIZE bytes)!" - echo "Rerun make to build a binary which doesn't use it!" - rm -- "$common_bufsiz_h.1k.OK" 2>/dev/null - { md5sum <.config | cut -d' ' -f1; stat -c "%Y" .config; } >"$common_bufsiz_h.1k.FAIL" - rm busybox_unstripped busybox 2>/dev/null -# Note: here we can do either a "malloc" or "std" build. -# "malloc" gives a bit bigger code: -# text bss filename -# 804355 5385 busybox.std -# 804618 4361 busybox.malloc -# but may have a smaller .bss (not guaranteed!). Use "pmap -x" to verify. - exitcmd="exit 1" - generate_malloc_and_exit - else - PREV_SIZE=1024 - test x"$method" = x"big" && PREV_SIZE=`cat -- "$common_bufsiz_h.1k.OK"` - round_down_COMMON_BUFSIZE $PREV_SIZE - PREV_BUFSIZE=$COMMON_BUFSIZE - - rm -- "$common_bufsiz_h.1k.FAIL" 2>/dev/null - echo $TAIL_SIZE >"$common_bufsiz_h.1k.OK" - round_down_COMMON_BUFSIZE $TAIL_SIZE - # emit message only if COMMON_BUFSIZE is indeed larger - test $COMMON_BUFSIZE -gt $PREV_BUFSIZE \ - && echo "Rerun make to use larger COMMON_BUFSIZE ($COMMON_BUFSIZE)" -#TODO: test $PREV_BUFSIZE -lt $TAIL_SIZE && PANIC!!! -#Code size with COMMON_BUFSIZE > 1024 may be bigger than code with COMMON_BUFSIZE = 1024! -#(currently we just hope "-32 and round down to 32" saves us) - - test $COMMON_BUFSIZE = 1024 && generate_1k_and_exit - generate_big_and_exit $COMMON_BUFSIZE "big" - fi + if test x"$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 build succeeded fitting 1k into _end[]. - # Try bigger COMMON_BUFSIZE if possible. - TAIL_SIZE=`cat -- "$common_bufsiz_h.1k.OK"` - round_down_COMMON_BUFSIZE $TAIL_SIZE - test $COMMON_BUFSIZE = 1024 && generate_1k_and_exit - generate_big_and_exit $COMMON_BUFSIZE "big" -fi - -if test -f "$common_bufsiz_h.1k.FAIL"; then - # Previous build FAILED to fit 1k into _end[]. - # Was it with same .config? - oldcfg=`cat -- "$common_bufsiz_h.1k.FAIL"` + # previous 1k build succeeded + oldcfg=`tail -n2 -- "$common_bufsiz_h.1k.OK"` curcfg=`md5sum <.config | cut -d' ' -f1; stat -c "%Y" .config` - # If yes, then build a "malloced" version + # config did not change if test x"$oldcfg" = x"$curcfg"; then - echo "Will not try 1k build, it failed before. Touch .config to override" -# Note: here we can do either a "malloc" or "std" build. - generate_malloc_and_exit + # 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 $COMMON_BUFSIZE "big" fi - # else: try 1k version - echo "New .config, will try 1k build" - rm -- "$common_bufsiz_h.1k.FAIL" - generate_1k_and_exit + # config did change + rm -rf -- "$common_bufsiz_h.1k.OK" fi # There was no 1k build yet. Try it. -- 2.25.1