linux-hardening - [PATCH 02/16] x86/build: Remove RWX sections and align on 4KB

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Message-Id: <aac3ce7c5aa706269d468fbe16129ee383deac2e.1662459668.git.baskov@ispras.ru>
Date:   Tue,  6 Sep 2022 13:41:06 +0300
From:   Evgeniy Baskov <baskov@...ras.ru>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     Evgeniy Baskov <baskov@...ras.ru>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Alexey Khoroshilov <khoroshilov@...ras.ru>,
        lvc-project@...uxtesting.org, x86@...nel.org,
        linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: [PATCH 02/16] x86/build: Remove RWX sections and align on 4KB

Avoid creating sections with maximal privileges to prepare for W^X
implementation. Align sections on page size (4KB) to allow protecting
them in page table.

Signed-off-by: Evgeniy Baskov <baskov@...ras.ru>
---
 arch/x86/kernel/vmlinux.lds.S | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 15f29053cec4..6587e0201b50 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -102,12 +102,11 @@ jiffies = jiffies_64;
 PHDRS {
 	text PT_LOAD FLAGS(5);          /* R_E */
 	data PT_LOAD FLAGS(6);          /* RW_ */
-#ifdef CONFIG_X86_64
-#ifdef CONFIG_SMP
+#if defined(CONFIG_X86_64) && defined(CONFIG_SMP)
 	percpu PT_LOAD FLAGS(6);        /* RW_ */
 #endif
-	init PT_LOAD FLAGS(7);          /* RWE */
-#endif
+	inittext PT_LOAD FLAGS(5);      /* R_E */
+	init PT_LOAD FLAGS(6);          /* RW_ */
 	note PT_NOTE FLAGS(0);          /* ___ */
 }
 
@@ -226,9 +225,10 @@ SECTIONS
 #endif
 
 	INIT_TEXT_SECTION(PAGE_SIZE)
-#ifdef CONFIG_X86_64
-	:init
-#endif
+	:inittext
+
+	. = ALIGN(PAGE_SIZE);
+
 
 	/*
 	 * Section for code used exclusively before alternatives are run. All
@@ -240,6 +240,7 @@ SECTIONS
 	.altinstr_aux : AT(ADDR(.altinstr_aux) - LOAD_OFFSET) {
 		*(.altinstr_aux)
 	}
+	:init
 
 	INIT_DATA_SECTION(16)
 
-- 
2.35.1