On 14 Nov 2024, at 13:44, Michal Meloun <m...@freebsd.org> wrote: > > While searching for the cause of armv7 kernel corruption after updating to > llvm19 lld, I came across an interesting problem. > > - The linker script does not list all generated sections. Specifically, the > data sections created by the linker set are not listed. > > - The linker can place these orphaned sections in any location (OK, with some > restrictions). See > https://maskray.me/blog/2024-06-02-understanding-orphan-sections. > > - Creating symbols outside a section is fragile and subject to error; the > linker may place an orphaned section between the symbol definition and the > following section. > > We ran into this problem many years ago, see > https://github.com/freebsd/freebsd-src/commit/6e764e36da019837d90e3b4b712871ee4442637a. > Unfortunately, we didn't fix it completely then, and we have to address the > same corruption again. > > I think we should be strict in this area and use '--orphan-handling=error' > for kernel linking. However, I'm not sure we can handle linker sets > gracefully. > > Any comments, contrary opinion or better solution ? Does anyone know how to > properly list all linker sets (mainly but not only 'set_<foo>_set') in linker > script and which section is appropriate for them ? .rodata?
I tried adding --orphan-handler=error, and on buildkernel (even for amd64) I get pretty soon: --- all_subdir_accf_data --- ld: error: accf_data.o:(.data) is being placed in '.data' ld: error: accf_data.o:(set_modmetadata_set) is being placed in 'set_modmetadata_set' ld: error: accf_data.o:(set_sysinit_set) is being placed in 'set_sysinit_set' ld: error: accf_data.o:(.debug_loc) is being placed in '.debug_loc' ld: error: accf_data.o:(.debug_abbrev) is being placed in '.debug_abbrev' ld: error: accf_data.o:(.debug_info) is being placed in '.debug_info' ld: error: accf_data.o:(.debug_ranges) is being placed in '.debug_ranges' ld: error: accf_data.o:(.debug_str) is being placed in '.debug_str' ld: error: accf_data.o:(.comment) is being placed in '.comment' ld: error: accf_data.o:(.debug_frame) is being placed in '.debug_frame' ld: error: accf_data.o:(.debug_line) is being placed in '.debug_line' ld: error: accf_data.o:(.llvm_addrsig) is being placed in '.llvm_addrsig' ld: error: accf_data.o:(.SUNW_ctf) is being placed in '.SUNW_ctf' ld: error: <internal>:(.note.gnu.build-id) is being placed in '.note.gnu.build-id' ld: error: <internal>:(.note.GNU-stack) is being placed in '.note.GNU-stack' ld: error: <internal>:(.symtab) is being placed in '.symtab' ld: error: <internal>:(.shstrtab) is being placed in '.shstrtab' ld: error: <internal>:(.strtab) is being placed in '.strtab' --- all_subdir_aic7xxx --- --- all_subdir_aic7xxx/ahc --- --- machine --- machine -> /home/dim/src/freebsd/src/sys/amd64/include --- all_subdir_accf_data --- *** [accf_data.ko.full] Error code 1 Not sure if those are all really orphaned, though? -Dimitry
