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From:   Kees Cook <keescook@chromium.org>
To:     Ingo Molnar <mingo@kernel.org>
Cc:     Kees Cook <keescook@chromium.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        Peter Collingbourne <pcc@google.com>,
        James Morse <james.morse@arm.com>,
        Borislav Petkov <bp@suse.de>, Ingo Molnar <mingo@redhat.com>,
        Russell King <linux@armlinux.org.uk>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Arvind Sankar <nivedita@alum.mit.edu>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nathan Chancellor <natechancellor@gmail.com>,
        Arnd Bergmann <arnd@arndb.de>, x86@kernel.org,
        clang-built-linux@googlegroups.com, linux-arch@vger.kernel.org,
        linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH v6 26/29] x86/boot/compressed: Reorganize zero-size section asserts
Date:   Fri, 21 Aug 2020 12:43:07 -0700
Message-Id: <20200821194310.3089815-27-keescook@chromium.org>
In-Reply-To: <20200821194310.3089815-1-keescook@chromium.org>
References: <20200821194310.3089815-1-keescook@chromium.org>
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For readability, move the zero-sized sections to the end after DISCARDS.

Signed-off-by: Kees Cook <keescook@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