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| author | Denys Vlasenko <vda.linux@googlemail.com> | 2016-04-21 16:26:30 +0200 |
|---|---|---|
| committer | Denys Vlasenko <vda.linux@googlemail.com> | 2016-04-21 17:39:11 +0200 |
| commit | e6a2f4cc5a47d3022bdf5ca2cacbaa5a8c5baf7a (patch) | |
| tree | 0962142ac9830312cd3df52994db41e8ac47c73c /libbb/common_bufsiz.c | |
| parent | 5598bdf0d3d46a865a4d23785e2d09e6db9be420 (diff) | |
| download | busybox-w32-e6a2f4cc5a47d3022bdf5ca2cacbaa5a8c5baf7a.tar.gz busybox-w32-e6a2f4cc5a47d3022bdf5ca2cacbaa5a8c5baf7a.tar.bz2 busybox-w32-e6a2f4cc5a47d3022bdf5ca2cacbaa5a8c5baf7a.zip | |
libbb: make bb_common_bufsiz1 1 kbyte, add capability to use bss tail for it
The config item is FEATURE_USE_BSS_TAIL. When it is off (default):
function old new delta
read_config 210 228 +18
doCommands 2279 2294 +15
ipneigh_list_or_flush 763 772 +9
ipaddr_list_or_flush 1256 1261 +5
display_process_list 1301 1306 +5
conspy_main 1378 1383 +5
do_lzo_compress 352 355 +3
do_lzo_decompress 565 567 +2
push 46 44 -2
inetd_main 2136 2134 -2
uevent_main 421 418 -3
addLines 97 92 -5
bb_common_bufsiz1 8193 1024 -7169
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 8/5 up/down: 62/-7181) Total: -7119 bytes
text data bss dec hex filename
829850 4086 9080 843016 cdd08 busybox_old
829901 4086 1904 835891 cc133 busybox_unstripped
FEATURE_USE_BSS_TAIL=y:
read_config 210 228 +18
doCommands 2279 2294 +15
ipneigh_list_or_flush 763 772 +9
ipaddr_list_or_flush 1256 1261 +5
display_process_list 1301 1306 +5
conspy_main 1378 1383 +5
do_lzo_compress 352 355 +3
do_lzo_decompress 565 567 +2
inetd_main 2136 2134 -2
bb_common_bufsiz1 8193 - -8193
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 8/1 up/down: 62/-8195) Total: -8133 bytes
text data bss dec hex filename
829850 4086 9080 843016 cdd08 busybox_old
829911 4086 880 834877 cbd3d busybox_unstripped
FIXME: setup_common_bufsiz() calls are missing.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'libbb/common_bufsiz.c')
| -rw-r--r-- | libbb/common_bufsiz.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/libbb/common_bufsiz.c b/libbb/common_bufsiz.c new file mode 100644 index 000000000..c16c361c9 --- /dev/null +++ b/libbb/common_bufsiz.c | |||
| @@ -0,0 +1,74 @@ | |||
| 1 | /* vi: set sw=4 ts=4: */ | ||
| 2 | /* | ||
| 3 | * Utility routines. | ||
| 4 | * | ||
| 5 | * Copyright (C) 2016 Denys Vlasenko | ||
| 6 | * | ||
| 7 | * Licensed under GPLv2, see file LICENSE in this source tree. | ||
| 8 | */ | ||
| 9 | //config:config FEATURE_USE_BSS_TAIL | ||
| 10 | //config: bool "Use the end of BSS page" | ||
| 11 | //config: default n | ||
| 12 | //config: help | ||
| 13 | //config: Attempt to reclaim a small unused part of BSS. | ||
| 14 | //config: | ||
| 15 | //config: Executables have the following parts: | ||
| 16 | //config: = read-only executable code and constants, also known as "text" | ||
| 17 | //config: = read-write data | ||
| 18 | //config: = non-initialized (zeroed on demand) data, also known as "bss" | ||
| 19 | //config: | ||
| 20 | //config: At link time, "text" is padded to a full page. At runtime, all "text" | ||
| 21 | //config: pages are mapped RO and executable. | ||
| 22 | //config: "Data" starts on the next page boundary, but is not padded | ||
| 23 | //config: to a full page at the end. "Bss" starts wherever "data" ends. | ||
| 24 | //config: At runtime, "data" pages are mapped RW and they are file-backed | ||
| 25 | //config: (this includes a small portion of "bss" which may live in the last | ||
| 26 | //config: partial page of "data"). | ||
| 27 | //config: Pages which are fully in "bss" are mapped to anonymous memory. | ||
| 28 | //config: | ||
| 29 | //config: "Bss" end is usually not page-aligned. There is an unused space | ||
| 30 | //config: in the last page. Linker marks its start with the "_end" symbol. | ||
| 31 | //config: | ||
| 32 | //config: This option will attempt to use that space for bb_common_bufsiz1[] | ||
| 33 | //config: array. If it fits after _end, it will be used, and COMMON_BUFSIZE | ||
| 34 | //config: will be enlarged from its guaranteed minimum size of 1 kbyte. | ||
| 35 | //config: This may require recompilation a second time, since value of _end | ||
| 36 | //config: is known only after final link. | ||
| 37 | //config: | ||
| 38 | //config: If you are getting a build error like this: | ||
| 39 | //config: appletlib.c:(.text.main+0xd): undefined reference to '_end' | ||
| 40 | //config: disable this option. | ||
| 41 | |||
| 42 | //kbuild:lib-y += common_bufsiz.o | ||
| 43 | |||
| 44 | #include "libbb.h" | ||
| 45 | #include "common_bufsiz.h" | ||
| 46 | |||
| 47 | #if !ENABLE_FEATURE_USE_BSS_TAIL | ||
| 48 | |||
| 49 | /* We use it for "global" data via *(struct global*)bb_common_bufsiz1. | ||
| 50 | * Since gcc insists on aligning struct global's members, it would be a pity | ||
| 51 | * (and an alignment fault on some CPUs) to mess it up. */ | ||
| 52 | char bb_common_bufsiz1[COMMON_BUFSIZE] ALIGNED(sizeof(long long)); | ||
| 53 | |||
| 54 | #else | ||
| 55 | |||
| 56 | # ifndef setup_common_bufsiz | ||
| 57 | /* | ||
| 58 | * It is not a "((void)0)" macro. It means we have to provide this function. | ||
| 59 | */ | ||
| 60 | char* bb_common_bufsiz1; | ||
| 61 | char* setup_common_bufsiz(void) | ||
| 62 | { | ||
| 63 | if (!bb_common_bufsiz1) | ||
| 64 | bb_common_bufsiz1 = xzalloc(COMMON_BUFSIZE); | ||
| 65 | return bb_common_bufsiz1; | ||
| 66 | } | ||
| 67 | # else | ||
| 68 | # ifndef bb_common_bufsiz1 | ||
| 69 | /* bb_common_bufsiz1[] is not aliased to _end[] */ | ||
| 70 | char bb_common_bufsiz1[COMMON_BUFSIZE] ALIGNED(sizeof(long long)); | ||
| 71 | # endif | ||
| 72 | # endif | ||
| 73 | |||
| 74 | #endif | ||