x86/boot/compressed/64: Use stack from trampoline memory

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.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180312100246.89175-3-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index f0c3a2f..1291551 100644 (file)
--- 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
 
+       /* Set up new stack */
+       leal    TRAMPOLINE_32BIT_STACK_END(%ecx), %esp
+
        /* Disable paging */
        movl    %cr0, %eax
        btrl    $X86_CR0_PG_BIT, %eax