Date: Thu, 14 Nov 2024 22:01:29 +0100 From: Dimitry Andric <dim@FreeBSD.org> To: "mmel@freebsd.org" <mmel@FreeBSD.org> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: llvm19 lld issue Message-ID: <8C24BC41-9782-45C9-AB8B-075943452519@FreeBSD.org> In-Reply-To: <192a3da4-6765-401a-a669-0359f8ac9487@FreeBSD.org>
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On 14 Nov 2024, at 13:44, Michal Meloun <mmel@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? -Dimitryhome | help
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