| From 74163ece3a8205f8f8200269214773d0931270d6 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Wed, 22 May 2024 10:32:43 -0700 |
| Subject: efi/libstub: zboot.lds: Discard .discard sections |
| |
| 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 ac8c0ef851581..af2c82f7bd902 100644 |
| --- a/drivers/firmware/efi/libstub/zboot.lds |
| +++ b/drivers/firmware/efi/libstub/zboot.lds |
| @@ -41,6 +41,7 @@ SECTIONS |
| } |
| |
| /DISCARD/ : { |
| + *(.discard .discard.*) |
| *(.modinfo .init.modinfo) |
| } |
| } |
| -- |
| 2.43.0 |
| |
