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When building LKL fuzzers with `LKL_FUZZING=1`, linking targets such as `hid-fuzzer` fails with the following linker error under lld: ld.lld: error: relocation R_X86_64_64 cannot be used against symbol 'system_state'; recompile with -fPIC >>> defined in tools/lkl/liblkl.a(lkl.o) >>> referenced by main.c:128 (init/main.c:128) >>> lkl.o:(.export_symbol+0x8) in archive tools/lkl/liblkl.a In Linux 6.5+ via commit ddb5cdb ("kbuild: generate KSYMTAB entries by modpost"), EXPORT_SYMBOL() was changed to emit `.quad sym` references into a temporary `.export_symbol` section. These entries serve as markers for modpost to generate `.vmlinux.export.c` and are intended to be dropped from the final vmlinux via `/DISCARD/`. Upstream places `*(.export_symbol)` in `COMMON_DISCARDS`. However, in LKL's `arch/lkl/kernel/vmlinux.lds.S`, `DISCARDS` is bypassed when `CONFIG_LKL_FUZZING` is enabled to prevent sanitizer-related sections (`.init_array`, `.eh_frame`) from being stripped. As a result, `.export_symbol` remains in `lkl.o` and `liblkl.a`. When linking fuzzers with `-fsanitize=fuzzer`, the linker defaults to PIE mode, where `ld.lld` strictly rejects absolute `R_X86_64_64` relocations in read-only sections. Fix this by explicitly discarding `*(.export_symbol)` in `arch/lkl/kernel/vmlinux.lds.S`. Closes: lkl#595 Signed-off-by: Cheng Lingfei <chenglingfei@foxmail.com>
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When building LKL fuzzers with
LKL_FUZZING=1, linking targets such ashid-fuzzerfails with the following linker error under lld:ld.lld: error: relocation R_X86_64_64 cannot be used against symbol
'system_state'; recompile with -fPIC
In Linux 6.5+ via commit ddb5cdb ("kbuild: generate KSYMTAB entries by modpost"), EXPORT_SYMBOL() was changed to emit
.quad symreferences into a temporary.export_symbolsection. These entries serve as markers for modpost to generate.vmlinux.export.cand are intended to be dropped from the final vmlinux via/DISCARD/.Upstream places
*(.export_symbol)inCOMMON_DISCARDS. However, in LKL'sarch/lkl/kernel/vmlinux.lds.S,DISCARDSis bypassed whenCONFIG_LKL_FUZZINGis enabled to prevent sanitizer-related sections (.init_array,.eh_frame) from being stripped. As a result,.export_symbolremains inlkl.oandliblkl.a.When linking fuzzers with
-fsanitize=fuzzer, the linker defaults to PIE mode, whereld.lldstrictly rejects absoluteR_X86_64_64relocations in read-only sections.Fix this by explicitly discarding
*(.export_symbol)inarch/lkl/kernel/vmlinux.lds.S.Closes: #595
Closes: #613