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Subject[PATCHv1, RFC 7/8] x86/mm: Hacks for boot-time switching between 4- and 5-level paging
Date
There're bunch of workaround to make switching between 4- and 5-level
paging compile.

All of them need to be addressed properly before upstreaming.

Not-yet-signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/Kconfig | 4 ++--
arch/x86/entry/entry_64.S | 5 +++++
arch/x86/kernel/head_64.S | 6 ++++--
arch/x86/xen/Kconfig | 2 +-
4 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0bf81e837cbf..c795207d8a3c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -100,7 +100,7 @@ config X86
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
select HAVE_ARCH_JUMP_LABEL
- select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
+ select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP && !X86_5LEVEL
select HAVE_ARCH_KGDB
select HAVE_ARCH_KMEMCHECK
select HAVE_ARCH_MMAP_RND_BITS if MMU
@@ -1980,7 +1980,7 @@ config RELOCATABLE

config RANDOMIZE_BASE
bool "Randomize the address of the kernel image (KASLR)"
- depends on RELOCATABLE
+ depends on RELOCATABLE && !X86_5LEVEL
default y
---help---
In support of Kernel Address Space Layout Randomization (KASLR),
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index edec30584eb8..9e868fd6d792 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -269,6 +269,11 @@ return_from_SYSCALL_64:
* Change top bits to match most significant bit (47th or 56th bit
* depending on paging mode) in the address.
*/
+#ifdef CONFIG_X86_5LEVEL
+#warning FIXME
+#undef __VIRTUAL_MASK_SHIFT
+#define __VIRTUAL_MASK_SHIFT 56
+#endif
shl $(64 - (__VIRTUAL_MASK_SHIFT+1)), %rcx
sar $(64 - (__VIRTUAL_MASK_SHIFT+1)), %rcx

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 2009d9849e98..9dcf7a4d8612 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -37,11 +37,13 @@
*
*/

-#define p4d_index(x) (((x) >> P4D_SHIFT) & (PTRS_PER_P4D-1))
#define pud_index(x) (((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))

-PGD_PAGE_OFFSET = pgd_index(__PAGE_OFFSET_BASE)
+#ifdef CONFIG_XEN
+/* FIXME */
+PGD_PAGE_OFFSET = pgd_index(__PAGE_OFFSET_BASE48)
PGD_START_KERNEL = pgd_index(__START_KERNEL_map)
+#endif
L3_START_KERNEL = pud_index(__START_KERNEL_map)

.text
diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
index 1be9667bd476..c1714cac7595 100644
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -4,7 +4,7 @@

config XEN
bool "Xen guest support"
- depends on PARAVIRT
+ depends on PARAVIRT && !X86_5LEVEL
select PARAVIRT_CLOCK
depends on X86_64 || (X86_32 && X86_PAE)
depends on X86_LOCAL_APIC && X86_TSC
--
2.11.0
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