[PATCH v6 26/29] x86/boot/compressed: Reorganize zero-size section asserts

Kees Cook keescook at chromium.org
Fri Aug 21 15:43:07 EDT 2020


For readability, move the zero-sized sections to the end after DISCARDS.

Signed-off-by: Kees Cook <keescook at chromium.org>
---
 arch/x86/boot/compressed/vmlinux.lds.S | 44 +++++++++++++++-----------
 1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S
index 3c2ee9a5bf43..ca544a16724b 100644
--- a/arch/x86/boot/compressed/vmlinux.lds.S
+++ b/arch/x86/boot/compressed/vmlinux.lds.S
@@ -42,19 +42,6 @@ SECTIONS
 		*(.rodata.*)
 		_erodata = . ;
 	}
-	.rel.dyn : {
-		*(.rel.*)
-	}
-	.rela.dyn : {
-		*(.rela.*)
-	}
-	.got : {
-		*(.got)
-	}
-	.got.plt : {
-		*(.got.plt)
-	}
-
 	.data :	{
 		_data = . ;
 		*(.data)
@@ -85,13 +72,34 @@ SECTIONS
 	ELF_DETAILS
 
 	DISCARDS
-}
 
-ASSERT(SIZEOF(.got) == 0, "Unexpected GOT entries detected!")
+	.got.plt (INFO) : {
+		*(.got.plt)
+	}
+	ASSERT(SIZEOF(.got.plt) == 0 ||
 #ifdef CONFIG_X86_64
-ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0x18, "Unexpected GOT/PLT entries detected!")
+	       SIZEOF(.got.plt) == 0x18,
 #else
-ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0xc, "Unexpected GOT/PLT entries detected!")
+	       SIZEOF(.got.plt) == 0xc,
 #endif
+	       "Unexpected GOT/PLT entries detected!")
+
+	/*
+	 * Sections that should stay zero sized, which is safer to
+	 * explicitly check instead of blindly discarding.
+	 */
+	.got : {
+		*(.got)
+	}
+	ASSERT(SIZEOF(.got) == 0, "Unexpected GOT entries detected!")
+
+	.rel.dyn : {
+		*(.rel.*)
+	}
+	ASSERT(SIZEOF(.rel.dyn) == 0, "Unexpected run-time relocations (.rel) detected!")
 
-ASSERT(SIZEOF(.rel.dyn) == 0 && SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations detected!")
+	.rela.dyn : {
+		*(.rela.*)
+	}
+	ASSERT(SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations (.rela) detected!")
+}
-- 
2.25.1




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