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Subject[tip: x86/build] x86/boot: Discard .discard.unreachable for arch/x86/boot/compressed/vmlinux
The following commit has been merged into the x86/build branch of tip:

Commit-ID: d6ee6529436a15a0541aff6e1697989ee7dc2c44
Author: Fangrui Song <>
AuthorDate: Wed, 20 May 2020 11:20:10 -07:00
Committer: Borislav Petkov <>
CommitterDate: Fri, 22 May 2020 12:42:07 +02:00

x86/boot: Discard .discard.unreachable for arch/x86/boot/compressed/vmlinux

With commit

ce5e3f909fc0 ("efi/printf: Add 64-bit and 8-bit integer support")

arch/x86/boot/compressed/vmlinux may have an undesired .discard.unreachable
section coming from drivers/firmware/efi/libstub/vsprintf.stub.o. That section
gets generated from unreachable() annotations when CONFIG_STACK_VALIDATION is

.discard.unreachable contains an R_X86_64_PC32 relocation which will be
warned about by LLD: a non-SHF_ALLOC section (.discard.unreachable) is
not part of the memory image, thus conceptually the distance between a
non-SHF_ALLOC and a SHF_ALLOC is not a constant which can be resolved at
link time:

% ld.lld -m elf_x86_64 -T arch/x86/boot/compressed/ ... -o arch/x86/boot/compressed/vmlinux
ld.lld: warning: vsprintf.c:(.discard.unreachable+0x0): has non-ABS relocation R_X86_64_PC32 against symbol ''

Reuse the DISCARDS macro which includes .discard.* to drop

[ bp: Massage and complete the commit message. ]

Reported-by: kbuild test robot <>
Signed-off-by: Fangrui Song <>
Signed-off-by: Borislav Petkov <>
Reviewed-by: Kees Cook <>
Tested-by: Arvind Sankar <>
Tested-by: Sedat Dilek <>
arch/x86/boot/compressed/ | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/x86/boot/compressed/ b/arch/x86/boot/compressed/
index 508cfa6..1031af1 100644
--- a/arch/x86/boot/compressed/
+++ b/arch/x86/boot/compressed/
@@ -73,4 +73,6 @@ SECTIONS
. = ALIGN(PAGE_SIZE); /* keep ZO size page aligned */
_end = .;
 \ /
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