ld.bfd --gc-sections not working properly in LoongArch #40

jiegec · 2024-01-25T03:05:54Z

Consider the following code (taken from u-boot-loongson):

// in a.c
extern void led_default_state();

int board_late_init(void) {
        led_default_state();
}

void spl_board_init(void) {
}

// in main.c
extern void spl_board_init();
int main() {
        spl_board_init();
}

Compile and link with -ffunctions-sections -fdata-sections -fno-plt:

gcc -c a.c -o a.o -fdata-sections -ffunction-sections -fno-plt
gcc -c main.c -o main.o -fdata-sections -ffunction-sections -fno-plt
gcc -Wl,--print-gc-sections -Wl,--gc-sections a.o main.o -o main

Output on loongarch:

/usr/bin/ld: removing unused section '.rodata.cst4' in file '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/usr/bin/ld: a.o: in function `board_late_init':
a.c:(.text.board_late_init+0x10): undefined reference to `led_default_state'
/usr/bin/ld: a.c:(.text.board_late_init+0x14): undefined reference to `led_default_state'
collect2: error: ld returned 1 exit status

Output on amd64:

/usr/bin/ld: removing unused section '.rodata.cst4' in file '/usr/lib/gcc/x86_64-linux-gnu/12/../../../x86_64-linux-gnu/Scrt1.o'
/usr/bin/ld: removing unused section '.data' in file '/usr/lib/gcc/x86_64-linux-gnu/12/../../../x86_64-linux-gnu/Scrt1.o'
/usr/bin/ld: removing unused section '.text.board_late_init' in file 'a.o'

You can see that .text.board_late_init is not properly GC-ed. If -fno-plt is removed, it works.

The text was updated successfully, but these errors were encountered:

jiegec · 2024-01-25T03:09:15Z

I have added some _bfd_error_handler calls to binutils and here is the output:

/buildroots/jiegec/prefix/binutils-gdb/bin/ld: In bfd_elf_gc_sections
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: keeping '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: keeping '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.board_late_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.spl_board_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.main' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: marking gc '.note.ABI-tag' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.note.ABI-tag' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: marking gc '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.main' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.text.main' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text.main' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.spl_board_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.text.spl_board_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.spl_board_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.spl_board_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.spl_board_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.board_late_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.text.board_late_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text.board_late_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text.board_late_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.board_late_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.board_late_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.board_late_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.board_late_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text.main' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.spl_board_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.main' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.main' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.main' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.main' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.main' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.main' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.main' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.main' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/libc.so.6'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/libc.so.6'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/libc.so.6'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/libc.so.6'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/libc.so.6'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/libc.so.6'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/libc.so.6'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/libc.so.6'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: marking gc '.eh_frame' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.eh_frame' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: marking gc '.note.gnu.build-id' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.note.gnu.build-id' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: marking gc '.fini_array' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.fini_array' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.fini_array' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.tm_clone_table' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.tm_clone_table' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.tm_clone_table' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.tm_clone_table' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtendS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.tm_clone_table' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtendS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.tm_clone_table' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtendS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.tm_clone_table' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.tm_clone_table' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.tm_clone_table' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtendS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.tm_clone_table' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtendS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.bss' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.bss' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.bss' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/libc.so.6'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/libc.so.6'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.sdata' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.sdata' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.sdata' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.sdata' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.sdata' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/libc.so.6'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: marking gc '.init_array' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.init_array' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.init_array' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtbeginS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: marking gc '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: marking gc '.eh_frame' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.eh_frame' from 'main.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: marking gc '.eh_frame' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtendS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in bfd_elf_gc_mark '.eh_frame' from '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/crtendS.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: removing unused section '.rodata.cst4' in file '/usr/lib/gcc/loongarch64-aosc-linux-gnu/13.2.0/../../../Scrt1.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: a.o: in function `board_late_init':
a.c:(.text.board_late_init+0x10): undefined reference to `led_default_state'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: a.c:(.text.board_late_init+0x14): undefined reference to `led_default_state'

It somehow marked .text.board_late_init for keeping from GC-ed.

jiegec · 2024-01-25T07:26:45Z

Possible bug:

/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in _bfd_elf_gc_mark_fdes '.text.spl_board_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in mark_entry '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in _bfd_elf_gc_mark_reloc '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in _bfd_elf_gc_mark_rsec, r_symndx = '11', sec '.eh_frame'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.spl_board_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in _bfd_elf_gc_mark_reloc '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in _bfd_elf_gc_mark_rsec, r_symndx = '12', sec '.eh_frame'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.spl_board_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in _bfd_elf_gc_mark_reloc '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in _bfd_elf_gc_mark_rsec, r_symndx = '11', sec '.eh_frame'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.spl_board_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in _bfd_elf_gc_mark_reloc '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in _bfd_elf_gc_mark_rsec, r_symndx = '8', sec '.eh_frame'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook '.eh_frame' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in loongarch_elf_gc_mark_hook return '.text.board_late_init' from 'a.o'
/buildroots/jiegec/prefix/binutils-gdb/bin/ld: in _bfd_elf_gc_mark '.text.board_late_init' from 'a.o'

When marking spl_board_init, it locates eh_frame FDE entry for board_late_init.

jiegec · 2024-01-25T07:37:14Z

The extra relocations of R_LARCH_ADD6 and R_LARCH_SUB6 are weird:


Relocation section '.rela.text.board_late_init' at offset 0x320 contains 4 entries:
  Offset          Info           Type           Sym. Value    Sym. Name + Addend
000000000010  00110000004b R_LARCH_GOT_PC_HI 0000000000000000 led_default_state + 0
000000000010  000000000064 R_LARCH_RELAX                        0
000000000014  00110000004c R_LARCH_GOT_PC_LO 0000000000000000 led_default_state + 0
000000000014  000000000064 R_LARCH_RELAX                        0

Relocation section '.rela.eh_frame' at offset 0x380 contains 8 entries:
  Offset          Info           Type           Sym. Value    Sym. Name + Addend
00000000001c  000600000063 R_LARCH_32_PCREL  0000000000000000 L0^A + 0
000000000020  000900000032 R_LARCH_ADD32     0000000000000034 L0^A + 0
000000000020  000600000037 R_LARCH_SUB32     0000000000000000 L0^A + 0
000000000040  000b00000063 R_LARCH_32_PCREL  0000000000000000 L0^A + 0
000000000044  000c00000032 R_LARCH_ADD32     000000000000001c L0^A + 0
000000000044  000b00000037 R_LARCH_SUB32     0000000000000000 L0^A + 0
000000000031  000800000069 R_LARCH_ADD6      0000000000000028 L0^A + 0
000000000031  00070000006a R_LARCH_SUB6      0000000000000010 L0^A + 0

Symbol table '.symtab' contains 19 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS a.c
     2: 0000000000000000     0 SECTION LOCAL  DEFAULT    1 .text
     3: 0000000000000000     0 SECTION LOCAL  DEFAULT    2 .data
     4: 0000000000000000     0 SECTION LOCAL  DEFAULT    3 .bss
     5: 0000000000000000     0 SECTION LOCAL  DEFAULT    4 .text.board_late_init
     6: 0000000000000000     0 NOTYPE  LOCAL  HIDDEN     4 L0^A
     7: 0000000000000010     0 NOTYPE  LOCAL  HIDDEN     4 L0^A
     8: 0000000000000028     0 NOTYPE  LOCAL  HIDDEN     4 L0^A
     9: 0000000000000034     0 NOTYPE  LOCAL  HIDDEN     4 L0^A
    10: 0000000000000000     0 SECTION LOCAL  DEFAULT    6 .text.spl_board_init
    11: 0000000000000000     0 NOTYPE  LOCAL  HIDDEN     6 L0^A
    12: 000000000000001c     0 NOTYPE  LOCAL  HIDDEN     6 L0^A
    13: 0000000000000000     0 SECTION LOCAL  DEFAULT    8 .note.GNU-stack
    14: 0000000000000000     0 SECTION LOCAL  DEFAULT    7 .comment
    15: 0000000000000000     0 SECTION LOCAL  DEFAULT    9 .eh_frame
    16: 0000000000000000    52 FUNC    GLOBAL DEFAULT    4 board_late_init
    17: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND led_default_state
    18: 0000000000000000    28 FUNC    GLOBAL DEFAULT    6 spl_board_init

jiegec · 2024-01-25T08:09:46Z

I found the bug: the relocations are not in-ordered: R_LARCH_ADD6 and R_LARCH_SUB6 appear after the ones for spl_board_init, and the code in binutils assumes the order:

  /* FIXME: octets_per_byte.  */
  for (cookie->rel = cookie->rels + ent->reloc_index;
       cookie->rel < cookie->relend
	 && cookie->rel->r_offset < ent->offset + ent->size;
       cookie->rel++)
    if (!_bfd_elf_gc_mark_reloc (info, sec, gc_mark_hook, cookie))
      return false;

It only checks if cookie->rel->r_offset < ent->offset + ent->size, not cookie->rel->r_offset >= ent->offset (cookie->rel->r_offset is 49, ent->offset is 56, ent->size is 32).

R_LARCH_ADD6 is generated for DW_CFA_advance_loc, which is in turn used for relaxation.

jiegec · 2024-01-25T08:25:08Z

Possible solutions:

Ensure the relocation offsets to be monotonic: best
Disable linker relaxation: sad
Handle the out of order case in mark_entry: might not handle all cases

xry111 · 2024-01-25T08:27:25Z

If you know how to fix it please send a patch to binutils@sourceware.org (with a DCO Signed-Off-By:) ASAP. The release of 2.42 is imminent.

jiegec · 2024-01-25T08:30:23Z

On the contrary, the order is correct in RISC-V:

Relocation section '.rela.text.board_late_init' at offset 0x3b0 contains 2 entries:
  Offset          Info           Type           Sym. Value    Sym. Name + Addend
000000000008  001400000013 R_RISCV_CALL_PLT  0000000000000000 led_default_state + 0
000000000008  000000000033 R_RISCV_RELAX                        0

Relocation section '.rela.eh_frame' at offset 0x3e0 contains 8 entries:
  Offset          Info           Type           Sym. Value    Sym. Name + Addend
00000000001c  000600000039 R_RISCV_32_PCREL  0000000000000000 .L0  + 0
000000000020  000a00000023 R_RISCV_ADD32     000000000000001c .L0  + 0
000000000020  000600000027 R_RISCV_SUB32     0000000000000000 .L0  + 0
000000000031  000900000035 R_RISCV_SET6      0000000000000016 .L0  + 0
000000000031  000800000034 R_RISCV_SUB6      0000000000000008 .L0  + 0
000000000044  000c00000039 R_RISCV_32_PCREL  0000000000000000 .L0  + 0
000000000048  000e00000023 R_RISCV_ADD32     000000000000000e .L0  + 0
000000000048  000c00000027 R_RISCV_SUB32     0000000000000000 .L0  + 0

xry111 · 2024-02-01T20:40:35Z

https://sourceware.org/pipermail/binutils/2024-February/132266.html

Pity: it seems the thought to test the Binutils pre-release with GCC trunk has never occurred to anyone (including myself) or we'll catch this much earlier!

cloudspurs · 2024-02-03T01:54:23Z

Possible solutions:

Ensure the relocation offsets to be monotonic: best

Disable linker relaxation: sad

Handle the out of order case in mark_entry: might not handle all cases

What version of your binutils? This bug has been fixed by Jinyang He on master branch(commit id: 7c93730fe50c22129e751d8479e64bc970b75aac). I will backport it to binutils 2.41 branch (binutils-2_41-branch).

jiegec · 2024-02-03T02:52:18Z

Possible solutions:

Ensure the relocation offsets to be monotonic: best

Disable linker relaxation: sad

Handle the out of order case in mark_entry: might not handle all cases

What version of your binutils? This bug has been fixed by Jinyang He on master branch(commit id: 7c93730fe50c22129e751d8479e64bc970b75aac). I will backport it to binutils 2.41 branch (binutils-2_41-branch).

I was using binutils 2.41. And I confirm that binutils 2.42 fixes the issue.

xry111 · 2024-02-03T11:47:19Z

Hmm, but in Binutils 2.42 several tests in the test suite for -Wl,--gc-sections still fail with GCC 14. Then they might be different problems...

cloudspurs · 2024-02-04T01:05:23Z

Hmm, but in Binutils 2.42 several tests in the test suite for -Wl,--gc-sections still fail with GCC 14. Then they might be different problems...

I will take a look today.

cloudspurs · 2024-02-05T08:07:14Z

Hmm, but in Binutils 2.42 several tests in the test suite for -Wl,--gc-sections still fail with GCC 14. Then they might be different problems...

I will take a look today.

These errors are caused by R_LARCH_ALIGN or mismatched error message. But, it may be fixed after Spring Festival.

…son-community/discussions#40

xen0n added the AREA: Toolchain label Jan 27, 2024

jiegec closed this as completed Feb 3, 2024

xen0n added a commit to xen0n/areweloongyet that referenced this issue Feb 5, 2024

docs(newsletter): this-week-in-loongarch-35: add coverage about loong…

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ld.bfd --gc-sections not working properly in LoongArch #40

ld.bfd --gc-sections not working properly in LoongArch #40

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ld.bfd --gc-sections not working properly in LoongArch #40

ld.bfd --gc-sections not working properly in LoongArch #40

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