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>
diff --git a/scripts/generate_BUFSIZ.sh b/scripts/generate_BUFSIZ.sh
index 8442619..718788e 100755
--- a/scripts/generate_BUFSIZ.sh
+++ b/scripts/generate_BUFSIZ.sh
@@ -36,11 +36,10 @@
}
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_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 @@
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.