The following commit has been merged into the x86/build branch of tip:

Commit-ID:     f6cff820877ff34839920ff9de9b912359cfb607
Gitweb:        https://git.kernel.org/tip/f6cff820877ff34839920ff9de9b912359cfb607
Author:        Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>
AuthorDate:    Tue, 23 Jun 2026 11:24:29 -04:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Fri, 10 Jul 2026 11:21:17 +02:00

x86/build: Only align ENTRY_TEXT to PMD_SIZE if necessary

PTI requires the begin and end of ENTRY_TEXT be aligned to PMD_SIZE.  SRSO
requires srso_alias_untrain_ret to be 2M aligned. This costs between 2-4 MiB
of RAM (depending on the size of the preceding section).  So, only align when
either of the two are enabled.

Co-developed-by: Jared White <jaredwhite@microsoft.com>
Signed-off-by: Jared White <jaredwhite@microsoft.com>
Signed-off-by: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://patch.msgid.link/20260623152430.1473481-1-hamzamahfooz@linux.microsoft.com
---
 arch/x86/kernel/vmlinux.lds.S | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 74e336d..10caf92 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -65,9 +65,15 @@ const_cpu_current_top_of_stack = cpu_current_top_of_stack;
 		__end_rodata_hpage_align = .;			\
 		__end_rodata_aligned = .;
 
+#if defined(CONFIG_MITIGATION_PAGE_TABLE_ISOLATION) || defined(CONFIG_MITIGATION_SRSO)
 #define ALIGN_ENTRY_TEXT_BEGIN	. = ALIGN(PMD_SIZE);
 #define ALIGN_ENTRY_TEXT_END	. = ALIGN(PMD_SIZE);
 #else
+#define ALIGN_ENTRY_TEXT_BEGIN
+#define ALIGN_ENTRY_TEXT_END
+#endif
+
+#else
 
 #define X86_ALIGN_RODATA_BEGIN
 #define X86_ALIGN_RODATA_END					\