[PATCH v5 32/36] x86/boot/compressed: Reorganize zero-size section asserts

[Kees Cook]

For readability, move the zero-sized sections to the end after DISCARDS
and mark them NOLOAD for good measure.

Signed-off-by: Kees Cook <keesc...@chromium.org>
---
 arch/x86/boot/compressed/vmlinux.lds.S | 42 +++++++++++++++-----------
 1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/arch/x86/boot/compressed/vmlinux.lds.S 
b/arch/x86/boot/compressed/vmlinux.lds.S
index 3c2ee9a5bf43..42dea70a5091 100644
--- a/arch/x86/boot/compressed/vmlinux.lds.S
+++ b/arch/x86/boot/compressed/vmlinux.lds.S
@@ -42,18 +42,16 @@ SECTIONS
                *(.rodata.*)
                _erodata = . ;
        }
-       .rel.dyn : {
-               *(.rel.*)
-       }
-       .rela.dyn : {
-               *(.rela.*)
-       }
-       .got : {
-               *(.got)
-       }
        .got.plt : {
                *(.got.plt)
        }
+       ASSERT(SIZEOF(.got.plt) == 0 ||
+#ifdef CONFIG_X86_64
+              SIZEOF(.got.plt) == 0x18,
+#else
+              SIZEOF(.got.plt) == 0xc,
+#endif
+              "Unexpected GOT/PLT entries detected!")
 
        .data : {
                _data = . ;
@@ -85,13 +83,23 @@ SECTIONS
        ELF_DETAILS
 
        DISCARDS
-}
 
-ASSERT(SIZEOF(.got) == 0, "Unexpected GOT entries detected!")
-#ifdef CONFIG_X86_64
-ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0x18, "Unexpected GOT/PLT 
entries detected!")
-#else
-ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0xc, "Unexpected GOT/PLT 
entries detected!")
-#endif
+       /*
+        * Sections that should stay zero sized, which is safer to
+        * explicitly check instead of blindly discarding.
+        */
+       .got (NOLOAD) : {
+               *(.got)
+       }
+       ASSERT(SIZEOF(.got) == 0, "Unexpected GOT entries detected!")
 
-ASSERT(SIZEOF(.rel.dyn) == 0 && SIZEOF(.rela.dyn) == 0, "Unexpected run-time 
relocations detected!")
+       /* ld.lld does not like .rel* sections being made "NOLOAD". */
+       .rel.dyn : {
+               *(.rel.*)
+       }
+       ASSERT(SIZEOF(.rel.dyn) == 0, "Unexpected run-time relocations (.rel) 
detected!")
+       .rela.dyn : {
+               *(.rela.*)
+       }
+       ASSERT(SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations (.rela) 
detected!")
+}
-- 
2.25.1