From: Nathan Chancellor nathan@kernel.org
[ Upstream commit 5134acb15d9ef27aa2b90aad46d4e89fcef79fdc ]
When building ARCH=loongarch defconfig + CONFIG_UNWINDER_ORC=y using LLVM, there is a warning from ld.lld when linking the EFI zboot image due to the use of unreachable() in number() in vsprintf.c:
ld.lld: warning: drivers/firmware/efi/libstub/lib.a(vsprintf.stub.o):(.discard.unreachable+0x0): has non-ABS relocation R_LARCH_32_PCREL against symbol ''
If the compiler cannot eliminate the default case for any reason, the .discard.unreachable section will remain in the final binary but the entire point of any section prefixed with .discard is that it is only used at compile time, so it can be discarded via /DISCARD/ in a linker script. The asm-generic vmlinux.lds.h includes .discard and .discard.* in the COMMON_DISCARDS macro but that is not used for zboot.lds, as it is not a kernel image linker script.
Add .discard and .discard.* to /DISCARD/ in zboot.lds, so that any sections meant to be discarded at link time are not included in the final zboot image. This issue is not specific to LoongArch, it is just the first architecture to select CONFIG_OBJTOOL, which defines annotate_unreachable() as an asm statement to add the .discard.unreachable section, and use the EFI stub.
Closes: https://github.com/ClangBuiltLinux/linux/issues/2023 Signed-off-by: Nathan Chancellor nathan@kernel.org Acked-by: Huacai Chen chenhuacai@loongson.cn Signed-off-by: Ard Biesheuvel ardb@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/firmware/efi/libstub/zboot.lds | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/firmware/efi/libstub/zboot.lds b/drivers/firmware/efi/libstub/zboot.lds index 93d33f68333b2..a7fffbad6d46a 100644 --- a/drivers/firmware/efi/libstub/zboot.lds +++ b/drivers/firmware/efi/libstub/zboot.lds @@ -34,6 +34,7 @@ SECTIONS }
/DISCARD/ : { + *(.discard .discard.*) *(.modinfo .init.modinfo) } }