renegade-project/linux-next
2
0
Fork 0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-27 14:43:58 +08:00
Code

x86/boot/compressed/64: Detect and handle 5-level paging at boot-time

Browse Source 
Prerequisite for fixing the current problem of instantaneous reboots when a
5-level paging kernel is booted on 4-level paging hardware.

At the same time this change prepares the decompression code to boot-time
switching between 4- and 5-level paging.

[ tglx: Folded the GCC < 5 fix. ]

Fixes: 77ef56e4f0 ("x86: Enable 5-level paging support via CONFIG_X86_5LEVEL=y")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: stable@vger.kernel.org
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: linux-mm@kvack.org
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/20171204124059.63515-2-kirill.shutemov@linux.intel.com
This commit is contained in:
Kirill A. Shutemov 2017-12-04 15:40:55 +03:00 committed by Thomas Gleixner
parent 947134d9b0
commit 08529078d8
3 changed files with 41 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/boot/compressed/Makefile
View File

@ -80,6 +80,7 @@ vmlinux-objs-$(CONFIG_RANDOMIZE_BASE) += $(obj)/kaslr.o
ifdef CONFIG_X86_64
vmlinux-objs-$(CONFIG_RANDOMIZE_BASE) += $(obj)/pagetable.o
vmlinux-objs-y += $(obj)/mem_encrypt.o
vmlinux-objs-y += $(obj)/pgtable_64.o
endif
$(obj)/eboot.o: KBUILD_CFLAGS += -fshort-wchar -mno-red-zone

16
arch/x86/boot/compressed/head_64.S
View File

@ -305,10 +305,18 @@ ENTRY(startup_64)
leaq boot_stack_end(%rbx), %rsp
#ifdef CONFIG_X86_5LEVEL
/* Check if 5-level paging has already enabled */
movq %cr4, %rax
testl $X86_CR4_LA57, %eax
jnz lvl5
/*
* Check if we need to enable 5-level paging.
* RSI holds real mode data and need to be preserved across
* a function call.
*/
pushq %rsi
call l5_paging_required
popq %rsi
/* If l5_paging_required() returned zero, we're done here. */
cmpq $0, %rax
je lvl5
/*
* At this point we are in long mode with 4-level paging enabled,

28
arch/x86/boot/compressed/pgtable_64.c Normal file
View File

@ -0,0 +1,28 @@
#include <asm/processor.h>
/*
* __force_order is used by special_insns.h asm code to force instruction
* serialization.
*
* It is not referenced from the code, but GCC < 5 with -fPIE would fail
* due to an undefined symbol. Define it to make these ancient GCCs work.
*/
unsigned long __force_order;
int l5_paging_required(void)
{
/* Check if leaf 7 is supported. */
if (native_cpuid_eax(0) < 7)
return 0;
/* Check if la57 is supported. */
if (!(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31))))
return 0;
/* Check if 5-level paging has already been enabled. */
if (native_read_cr4() & X86_CR4_LA57)
return 0;
return 1;
}