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>

diff --git a/arch/s390/boot/vmlinux.lds.S b/arch/s390/boot/vmlinux.lds.S
index 389df0e0d9e5d58fb89025e7e0eb4c532569e35e..cb4e95c691ae06e8cc21e2c14cc2021eb889bbec 100644 (file)
--- a/arch/s390/boot/vmlinux.lds.S
+++ b/arch/s390/boot/vmlinux.lds.S
@@ -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)

diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index d231a3faf9818d2bcc3475317ab51b219b6b13eb..725e3122c2143f344521b2d47183999ff8fd6d2a 100644 (file)
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -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/ : {