Re: [PATCH v2 mips-next 3/4] MIPS: vmlinux.lds.S: catch bad .got, .plt and .rel.dyn at link time
From: Fāng-ruì Sòng <hidden>
Date: 2021-01-06 20:23:02
Also in:
lkml, stable
On Wed, Jan 6, 2021 at 12:08 PM Alexander Lobakin [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 <redacted> # .got Suggested-by: Fangrui Song <redacted> # .rel.dyn Signed-off-by: Alexander Lobakin <redacted> --- 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