lkml.org 
[lkml]   [2017]   [Nov]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCHv2 0/4] x86: 5-level related changes into decompression code
On Wed, Nov 29, 2017 at 05:48:51PM +0000, Borislav Petkov wrote:
> On Wed, Nov 29, 2017 at 08:08:31PM +0300, Kirill A. Shutemov wrote:
> > We're really early in the boot -- startup_64 in decompression code -- and
> > I don't know a way print a message there. Is there a way?
> >
> > no_longmode handled by just hanging the machine. Is it enough for no_la57
> > case too?
>
> Patch pls.

The patch below on top of patch 2/4 from this patch would do the trick.

Please give it a shot.

From 95b5489d1f4ea03c6226d13eb6797825234489d6 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Date: Thu, 30 Nov 2017 10:23:53 +0300
Subject: [PATCH] x86/boot/compressed/64: Print error if 5-level paging is not
supported

We cannot proceed booting if the machine doesn't support the paging mode
kernel was compiled for.

Getting error the usual way -- via validate_cpu() -- is not going to
work. We need to enable appropriate paging mode before that, otherwise
kernel would triple-fault during KASLR setup.

This code will go away once we get support for boot-time switching
between paging modes.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/boot/compressed/misc.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index b50c42455e25..5205e848dc33 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -40,6 +40,8 @@
/* Functions used by the included decompressor code below. */
void *memmove(void *dest, const void *src, size_t n);

+int l5_paging_required(void);
+
/*
* This is set up by the setup-routine at boot-time
*/
@@ -362,6 +364,13 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
console_init();
debug_putstr("early console in extract_kernel\n");

+ if (IS_ENABLED(CONFIG_X86_5LEVEL) && !l5_paging_required()) {
+ error("The kernel is compiled with 5-level paging enabled, "
+ "but the CPU doesn't support la57\n"
+ "Unable to boot - please use "
+ "a kernel appropriate for your CPU.\n");
+ }
+
free_mem_ptr = heap; /* Heap */
free_mem_end_ptr = heap + BOOT_HEAP_SIZE;

--
Kirill A. Shutemov
\
 
 \ /
  Last update: 2017-11-30 08:32    [W:0.106 / U:0.156 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site