On Wed, Jan 6, 2021 at 12:08 PM Alexander Lobakin alobakin@pm.me wrote:
Catch any symbols placed in .got, .got.plt, .plt, .rel.dyn or .rela.dyn and check for these sections to be zero-sized at link time.
At least two of them were noticed in real builds:
mips-alpine-linux-musl-ld: warning: orphan section `.rel.dyn' from `init/main.o' being placed in section `.rel.dyn'
ld.lld: warning: <internal>:(.got) is being placed in '.got'
Adopted from x86/kernel/vmlinux.lds.S.
Reported-by: Nathan Chancellor natechancellor@gmail.com # .got Suggested-by: Fangrui Song maskray@google.com # .rel.dyn Signed-off-by: Alexander Lobakin alobakin@pm.me
arch/mips/kernel/vmlinux.lds.S | 35 ++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+)
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S index 5d6563970ab2..05eda9d9a7d5 100644 --- a/arch/mips/kernel/vmlinux.lds.S +++ b/arch/mips/kernel/vmlinux.lds.S @@ -227,4 +227,39 @@ SECTIONS *(.pdr) *(.reginfo) }
/** Sections that should stay zero sized, which is safer to* explicitly check instead of blindly discarding.*/.got : {*(.got)*(.igot.*)}ASSERT(SIZEOF(.got) == 0, "Unexpected GOT entries detected!").got.plt (INFO) : {*(.got.plt)}ASSERT(SIZEOF(.got.plt) == 0, "Unexpected GOT/PLT entries detected!")
(INFO) drops the SHF_ALLOC flag from the output section (It does not mean "informational"). INFO is not need here. The diff from 815d680771ae09080d2da83dac2647c08cdf99ce "x86/build: Enforce an empty .got.plt section" is not needed.
.plt : {*(.plt)*(.plt.*)*(.iplt)}ASSERT(SIZEOF(.plt) == 0, "Unexpected run-time procedure linkages detected!").rel.dyn : {*(.rel.*)*(.rel_*)}ASSERT(SIZEOF(.rel.dyn) == 0, "Unexpected run-time relocations (.rel) detected!").rela.dyn : {*(.rela.*)*(.rela_*)}ASSERT(SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations (.rela) detected!")}
x86 has both .rel.dyn and .rela.dyn because i386 psABI uses REL while x86-64 psABI uses RELA, but mips does not need .rela.dyn
-- 2.30.0