As the first step on using trampoline memory, let's make 32-bit code use
stack there.
Separate stack is required to return back from trampoline and we cannot
user stack from 64-bit mode as it may be above 4G.
Signed-off-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
---
arch/x86/boot/compressed/head_64.S | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/x86/boot/compressed/head_64.S
b/arch/x86/boot/compressed/head_64.S
index f0c3a2f7e528..0014459d9bcb 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -33,6 +33,7 @@
#include <asm/processor-flags.h>
#include <asm/asm-offsets.h>
#include <asm/bootparam.h>
+#include "pgtable.h"
/*
* Locally defined symbols should be marked hidden:
@@ -359,6 +360,8 @@ ENTRY(startup_64)
pushq %rax
lretq
lvl5:
+ /* Restore the stack, the 32-bit trampoline uses its own stack */
+ leaq boot_stack_end(%rbx), %rsp
/*
* cleanup_trampoline() would restore trampoline memory.
@@ -513,6 +516,9 @@ compatible_mode:
movl %eax, %ds
movl %eax, %ss
+ /* Setup new stack */
+ leal TRAMPOLINE_32BIT_STACK_END(%ecx), %esp
+
/* Disable paging */
movl %cr0, %eax
btrl $X86_CR0_PG_BIT, %eax
--
2.16.1
