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[v3,02/24] x86/build: Remove RWX sections and align on 4KB

Message ID fc137bb4ff6b12d2701ef8e960c0f5b9c5c417ef.1668958803.git.baskov@ispras.ru (mailing list archive)
State Superseded
Headers show
Series x86_64: Improvements at compressed kernel stage | expand

Commit Message

Evgeniy Baskov Nov. 22, 2022, 11:12 a.m. UTC 
Avoid creating sections simultaneously writable and readable
to prepare for W^X implementation. Align sections on page size (4KB) to
allow protecting them in the page tables.

Split init code form ".init" segment into separate R_X ".inittext"
segment and make ".init" segment non-executable.

Also add these segments to x86_32 architecture for consistency.
Currently paging is disabled in x86_32 in compressed kernel, so
protection is not applied anyways, but .init code was incorrectly
placed in non-executable ".data" segment. This should not change
anything meaningful in memory layout now, but might be required in case
memory protection will also be implemented in compressed kernel for
x86_32.

Tested-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Evgeniy Baskov <baskov@ispras.ru>
---
 arch/x86/kernel/vmlinux.lds.S | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)
diff mbox series

Patch

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)