On Tue, Jul 18, 2017 at 11:40 PM, Thomas Petazzoni <[email protected]> wrote: > Hello, > > On Sat, 15 Jul 2017 14:44:21 +0200, Denys Vlasenko wrote: > >> Can you investigate this further? >> LIBBUSYBOX build results in entire busybox code being put into a library. >> >> nm -D libbusybox.so.1.28.0.git >> >> shows that there are only defined entry points to each applet's main(): >> >> 0007b159 T bunzip2_main >> 0007c8db T bzip2_main >> 000677bb T cal_main >> 0008e08e T cat_main >> >> (so, at max less than 350 entry points), and references to libc functions: >> >> U asprintf >> U atof >> U atoi >> >> No internal libbb functions or variables are exposed. >> >> I don't understand the error messages you are seeing. bb_errno should >> have hidden visibility, >> meaning that it is an internal (to libbusybox.so) label, and all >> references to it >> should be resolved without any shared linker magic. .LCn labels are >> similar, they are >> referring to text strings (messages and such). >> >> What is going on? Why your linker has relocations between individual >> .o files which go >> to the same library? > > I'm not really sure what's going on. But the problem can very easily be > reproduced: > > $ git clone git://git.buildroot.org/buildroot > $ cd buildroot/ > $ cat > .config <<EOF > BR2_sparc=y > BR2_TOOLCHAIN_EXTERNAL=y > BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD=y > BR2_TOOLCHAIN_EXTERNAL_URL="http://autobuild.buildroot.org/toolchains/tarballs/br-sparc-uclibc-2017.05-1078-g95b1dae.tar.bz2"; > BR2_TOOLCHAIN_EXTERNAL_GCC_6=y > BR2_TOOLCHAIN_EXTERNAL_HEADERS_4_1=y > BR2_TOOLCHAIN_EXTERNAL_LOCALE=y > # BR2_TOOLCHAIN_EXTERNAL_HAS_THREADS_DEBUG is not set > BR2_TOOLCHAIN_EXTERNAL_CXX=y > BR2_INIT_NONE=y > BR2_SYSTEM_BIN_SH_NONE=y > BR2_PACKAGE_BUSYBOX_INDIVIDUAL_BINARIES=y > # BR2_TARGET_ROOTFS_TAR is not set > EOF > $ make olddefconfig > $ make > > It builds only Busybox, so it's very quick to reach the build failure. > This time, I got: > > libbb/lib.a(appletlib.o): In function `find_applet_by_name': > appletlib.c:(.text.find_applet_by_name+0x14): relocation truncated to fit: > R_SPARC_GOT13 against symbol `applet_nameofs' defined in > .rodata.applet_nameofs section in libbb/lib.a(appletlib.o) > appletlib.c:(.text.find_applet_by_name+0x18): relocation truncated to fit: > R_SPARC_GOT13 against symbol `applet_names' defined in .rodata.applet_names > section in libbb/lib.a(appletlib.o) > libbb/lib.a(appletlib.o): In function `bb_show_usage': > appletlib.c:(.text.bb_show_usage+0x10): relocation truncated to fit: > R_SPARC_GOT13 against symbol `applet_name' defined in COMMON section in > libbb/lib.a(appletlib.o) > appletlib.c:(.text.bb_show_usage+0x54): relocation truncated to fit: > R_SPARC_GOT13 against symbol `bb_banner' defined in .rodata.bb_banner section > in libbb/lib.a(messages.o) > libbb/lib.a(appletlib.o): In function `lbb_prepare': > appletlib.c:(.text.lbb_prepare+0x18): relocation truncated to fit: > R_SPARC_GOT13 against symbol `bb_errno' defined in COMMON section in > libbb/lib.a(ptr_to_globals.o) > appletlib.c:(.text.lbb_prepare+0x20): relocation truncated to fit: > R_SPARC_GOT13 against symbol `applet_name' defined in COMMON section in > libbb/lib.a(appletlib.o) > libbb/lib.a(appletlib.o): In function `run_applet_no_and_exit': > appletlib.c:(.text.run_applet_no_and_exit+0x28): relocation truncated to fit: > R_SPARC_GOT13 against symbol `xfunc_error_retval' defined in > .data.xfunc_error_retval section in libbb/lib.a(default_error_retval.o) > appletlib.c:(.text.run_applet_no_and_exit+0x38): relocation truncated to fit: > R_SPARC_GOT13 against symbol `applet_name' defined in COMMON section in > libbb/lib.a(appletlib.o) > appletlib.c:(.text.run_applet_no_and_exit+0xb0): relocation truncated to fit: > R_SPARC_GOT13 against symbol `applet_main' defined in > .data.rel.ro.applet_main section in libbb/lib.a(appletlib.o) > appletlib.c:(.text.run_applet_no_and_exit+0xcc): relocation truncated to fit: > R_SPARC_GOT13 against symbol `applet_suid' defined in .rodata.applet_suid > section in libbb/lib.a(appletlib.o) > appletlib.c:(.text.run_applet_no_and_exit+0x11c): additional relocation > overflows omitted from the output > collect2: error: ld returned 1 exit status > > When I build with my patches (the build is successful), and then look > at libbbusybox.so with readelf, the .got section is indeed very small, > much smaller than the 8 KB limit detailed in gcc's documentation about > -fpic vs. -fPIC: > > $ ./output/host/usr/bin/sparc-linux-readelf -a > output/target/lib/libbusybox.so.1.26.2 | grep "\.got" > [17] .got PROGBITS 000dc000 0cc000 00021c 04 WA 0 0 > 4 > > So the size is only 0x21c. > > Any idea on how to investigate this further?
I think what happens is compiler does not know where applet_names[] are, assumes it's in another library and generates a reloc. Then, the "short" fpic reloc does not work at link time. _______________________________________________ busybox mailing list [email protected] http://lists.busybox.net/mailman/listinfo/busybox
