[tip: x86/boot] x86/kernel: Move ENTRY_TEXT to the start of the image

[tip-bot2 for Ard Biesheuvel]

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

Commit-ID:     35350eb689e68897d996b762832782e2e791eb74
Gitweb:        https://git.kernel.org/tip/35350eb689e68897d996b762832782e2e791eb74
Author:        Ard Biesheuvel <ardb@xxxxxxxxxx>
AuthorDate:    Thu, 05 Dec 2024 12:28:10 +01:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Thu, 05 Dec 2024 13:18:55 +01:00

x86/kernel: Move ENTRY_TEXT to the start of the image

Since commit:

  7734a0f31e99 ("x86/boot: Robustify calling startup_{32,64}() from the decompressor code")

it is no longer necessary for .head.text to appear at the start of the
image. Since ENTRY_TEXT needs to appear PMD-aligned, it is easier to
just place it at the start of the image, rather than line it up with the
end of the .text section. The amount of padding required should be the
same, but this arrangement also permits .head.text to be split off and
emitted separately, which is needed by a subsequent change.

Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Link: https://lore.kernel.org/r/20241205112804.3416920-14-ardb+git@xxxxxxxxxx
---
 arch/x86/kernel/vmlinux.lds.S | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index fab3ac9..1ce7889 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -121,19 +121,6 @@ SECTIONS
 	.text :  AT(ADDR(.text) - LOAD_OFFSET) {
 		_text = .;
 		_stext = .;
-		/* bootstrapping code */
-		HEAD_TEXT
-		TEXT_TEXT
-		SCHED_TEXT
-		LOCK_TEXT
-		KPROBES_TEXT
-		SOFTIRQENTRY_TEXT
-#ifdef CONFIG_MITIGATION_RETPOLINE
-		*(.text..__x86.indirect_thunk)
-		*(.text..__x86.return_thunk)
-#endif
-		STATIC_CALL_TEXT
-
 		ALIGN_ENTRY_TEXT_BEGIN
 		*(.text..__x86.rethunk_untrain)
 		ENTRY_TEXT
@@ -147,6 +134,19 @@ SECTIONS
 		*(.text..__x86.rethunk_safe)
 #endif
 		ALIGN_ENTRY_TEXT_END
+
+		/* bootstrapping code */
+		HEAD_TEXT
+		TEXT_TEXT
+		SCHED_TEXT
+		LOCK_TEXT
+		KPROBES_TEXT
+		SOFTIRQENTRY_TEXT
+#ifdef CONFIG_MITIGATION_RETPOLINE
+		*(.text..__x86.indirect_thunk)
+		*(.text..__x86.return_thunk)
+#endif
+		STATIC_CALL_TEXT
 		*(.gnu.warning)
 
 	} :text = 0xcccccccc