From: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
This patch puts the code from head.S in a special .bootstrap.text
section.
I'm working on a patch to reorder the functions in the kernel (I'll post
that later), but for x86-64 at least the kernel bootstrap requires that the
head.S functions are on the very first page/pages of the kernel text. This
is understandable since the bootstrap is complex enough already and not a
problem at all, it just means they aren't allowed to be reordered. This
patch puts these special functions into a separate section to document this,
and to guarantee this in the light of possibly reordering the rest later.
(So this patch doesn't fix a bug per se, but makes things more robust by
making the order of these functions explicit)
Signed-off-by: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxx>
---
arch/x86_64/kernel/head.S | 1 +
arch/x86_64/kernel/vmlinux.lds.S | 1 +
2 files changed, 2 insertions(+)
Index: linux/arch/x86_64/kernel/head.S
===================================================================
--- linux.orig/arch/x86_64/kernel/head.S
+++ linux/arch/x86_64/kernel/head.S
@@ -26,6 +26,7 @@
*/
.text
+ .section .bootstrap.text
.code32
.globl startup_32
/* %bx: 1 if coming from smp trampoline on secondary cpu */
Index: linux/arch/x86_64/kernel/vmlinux.lds.S
===================================================================
--- linux.orig/arch/x86_64/kernel/vmlinux.lds.S
+++ linux/arch/x86_64/kernel/vmlinux.lds.S
@@ -20,6 +20,7 @@ SECTIONS
phys_startup_64 = startup_64 - LOAD_OFFSET;
_text = .; /* Text and read-only data */
.text : AT(ADDR(.text) - LOAD_OFFSET) {
+ *(.bootstrap.text)
*(.text)
SCHED_TEXT
LOCK_TEXT
-
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