Commit 30226853 authored Feb 07, 2024 by Nathan Chancellor Committed by Heiko Carstens Feb 14, 2024

s390: vmlinux.lds.S: explicitly handle '.got' and '.plt' sections

When building with CONFIG_LD_ORPHAN_WARN after selecting
CONFIG_ARCH_HAS_LD_ORPHAN_WARN, there are a lot of warnings around the
GOT and PLT sections:

s390-linux-ld: warning: orphan section `.plt' from `arch/s390/kernel/head64.o' being placed in section `.plt'
s390-linux-ld: warning: orphan section `.got' from `arch/s390/kernel/head64.o' being placed in section `.got'
s390-linux-ld: warning: orphan section `.got.plt' from `arch/s390/kernel/head64.o' being placed in section `.got.plt'
s390-linux-ld: warning: orphan section `.iplt' from `arch/s390/kernel/head64.o' being placed in section `.iplt'
s390-linux-ld: warning: orphan section `.igot.plt' from `arch/s390/kernel/head64.o' being placed in section `.igot.plt'

s390-linux-ld: warning: orphan section `.iplt' from `arch/s390/boot/head.o' being placed in section `.iplt'
s390-linux-ld: warning: orphan section `.igot.plt' from `arch/s390/boot/head.o' being placed in section `.igot.plt'
s390-linux-ld: warning: orphan section `.got' from `arch/s390/boot/head.o' being placed in section `.got'

Currently, only the '.got' section is actually emitted in the final
binary. In a manner similar to other architectures, put the '.got'
section near the '.data' section and coalesce the PLT sections,
checking that the final section is zero sized, which is a safe/tested
approach versus full discard.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240207-s390-lld-and-orphan-warn-v1-3-8a665b3346ab@kernel.org

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

parent bdf2cd27

arch/s390/boot/vmlinux.lds.S

+16 −0

Original line number	Diff line number	Diff line
		@@ -39,6 +39,9 @@ SECTIONS
		(.rodata.)
		_erodata = . ;
		}
		.got : {
		*(.got)
		}
		NOTES
		.data : {
		_data = . ;
		@@ -118,6 +121,19 @@ SECTIONS
		}
		_end = .;

		/*
		* Sections that should stay zero sized, which is safer to
		* explicitly check instead of blindly discarding.
		*/
		.got.plt : {
		*(.got.plt)
		}
		ASSERT(SIZEOF(.got.plt) == 0, "Unexpected GOT/PLT entries detected!")
		.plt : {
		(.plt) (.plt.) (.iplt) *(.igot .igot.plt)
		}
		ASSERT(SIZEOF(.plt) == 0, "Unexpected run-time procedure linkages detected!")

		/* Sections to be discarded */
		/DISCARD/ : {
		*(.eh_frame)

arch/s390/kernel/vmlinux.lds.S

+16 −0

Original line number	Diff line number	Diff line
		@@ -62,6 +62,9 @@ SECTIONS
		.data.rel.ro : {
		(.data.rel.ro .data.rel.ro.)
		}
		.got : {
		*(.got)
		}

		. = ALIGN(PAGE_SIZE);
		_sdata = .; /* Start of data section */
		@@ -241,6 +244,19 @@ SECTIONS
		DWARF_DEBUG
		ELF_DETAILS

		/*
		* Sections that should stay zero sized, which is safer to
		* explicitly check instead of blindly discarding.
		*/
		.got.plt : {
		*(.got.plt)
		}
		ASSERT(SIZEOF(.got.plt) == 0, "Unexpected GOT/PLT entries detected!")
		.plt : {
		(.plt) (.plt.) (.iplt) *(.igot .igot.plt)
		}
		ASSERT(SIZEOF(.plt) == 0, "Unexpected run-time procedure linkages detected!")

		/* Sections to be discarded */
		DISCARDS
		/DISCARD/ : {