From: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>
To: x86@kernel.org
Cc: Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ard Biesheuvel <ardb@kernel.org>,
Nathan Chancellor <nathan@kernel.org>,
linux-kernel@vger.kernel.org,
Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>,
Jared White <jaredwhite@microsoft.com>
Subject: [PATCH v2 1/2] x86/build: only align ENTRY_TEXT to PMD_SIZE if necessary
Date: Tue, 23 Jun 2026 11:24:29 -0400 [thread overview]
Message-ID: <20260623152430.1473481-1-hamzamahfooz@linux.microsoft.com> (raw)
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 PTI is enabled or SRSO is 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>
---
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 4711a35e706c..53519fa7c772 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -65,8 +65,14 @@ 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
--
2.54.0
next reply other threads:[~2026-06-23 15:25 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-23 15:24 Hamza Mahfooz [this message]
2026-06-23 15:24 ` [PATCH v2 2/2] x86/mm/64: free the gap between BSS_MAIN and BSS_DECRYPTED Hamza Mahfooz
2026-07-09 22:36 ` Borislav Petkov
2026-07-09 23:14 ` [tip: x86/cleanups] x86/build: Only align ENTRY_TEXT to PMD_SIZE if necessary tip-bot2 for Hamza Mahfooz
2026-07-10 9:30 ` [tip: x86/build] " tip-bot2 for Hamza Mahfooz
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