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@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: https://lore.kernel.org/r/20241205112804.3416920-14-ardb+git@google.com

diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index fab3ac9a4574ab406fee90e6c5d86fd4a81af319..1ce7889cd12b5aa9dfd1baee7ac11e2a372b5409 100644 (file)
--- 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