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Subject[PATCHv7 10/19] x86/mm: Make __PHYSICAL_MASK_SHIFT and __VIRTUAL_MASK_SHIFT dynamic
Date
For boot-time switching between paging modes, we need to be able to
adjust physical and virtual mask shifts.

It has significant effect on kernel image size:

text data bss dec hex filename
10710666 4880000 860160 16450826 fb050a vmlinux.before
10735996 4880000 860160 16476156 fb67fc vmlinux.after

The change is mostly due to __PHYSICAL_MASK_SHIFT change: the value is
used in pte_pfn() and many other page table manipulation routines
(directly or indirectly).

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/entry/entry_64.S | 12 ++++++++++++
arch/x86/include/asm/page_64_types.h | 4 ++--
arch/x86/mm/dump_pagetables.c | 8 ++++++--
arch/x86/mm/kaslr.c | 4 +++-
4 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 49167258d587..eec0ca064c67 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -268,8 +268,20 @@ 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
+ testl $1, pgtable_l5_enabled(%rip)
+ jz 1f
+ shl $(64 - 57), %rcx
+ sar $(64 - 57), %rcx
+ jmp 2f
+1:
+ shl $(64 - 48), %rcx
+ sar $(64 - 48), %rcx
+2:
+#else
shl $(64 - (__VIRTUAL_MASK_SHIFT+1)), %rcx
sar $(64 - (__VIRTUAL_MASK_SHIFT+1)), %rcx
+#endif

/* If this changed %rcx, it was not canonical */
cmpq %rcx, %r11
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 0126d6bc2eb1..79d2180ffdec 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -52,8 +52,8 @@

/* See Documentation/x86/x86_64/mm.txt for a description of the memory map. */
#ifdef CONFIG_X86_5LEVEL
-#define __PHYSICAL_MASK_SHIFT 52
-#define __VIRTUAL_MASK_SHIFT 56
+#define __PHYSICAL_MASK_SHIFT (pgtable_l5_enabled ? 52 : 46)
+#define __VIRTUAL_MASK_SHIFT (pgtable_l5_enabled ? 56 : 47)
#else
#define __PHYSICAL_MASK_SHIFT 46
#define __VIRTUAL_MASK_SHIFT 47
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 2eabd07ae2d2..a1d983a45ab0 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -82,8 +82,8 @@ static struct addr_marker address_markers[] = {
{ 0/* VMALLOC_START */, "vmalloc() Area" },
{ 0/* VMEMMAP_START */, "Vmemmap" },
#ifdef CONFIG_KASAN
- { KASAN_SHADOW_START, "KASAN shadow" },
- { KASAN_SHADOW_END, "KASAN shadow end" },
+ { 0/* KASAN_SHADOW_START */, "KASAN shadow" },
+ { 0/* KASAN_SHADOW_END */, "KASAN shadow end" },
#endif
# ifdef CONFIG_X86_ESPFIX64
{ ESPFIX_BASE_ADDR, "ESPfix Area", 16 },
@@ -515,6 +515,10 @@ static int __init pt_dump_init(void)
address_markers[LOW_KERNEL_NR].start_address = PAGE_OFFSET;
address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
address_markers[VMEMMAP_START_NR].start_address = VMEMMAP_START;
+#ifdef CONFIG_KASAN
+ address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START;
+ address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END;
+#endif
#endif
#ifdef CONFIG_X86_32
address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
index e6420b18f6e0..5597dd0635dd 100644
--- a/arch/x86/mm/kaslr.c
+++ b/arch/x86/mm/kaslr.c
@@ -62,7 +62,7 @@ static __initdata struct kaslr_memory_region {
unsigned long *base;
unsigned long size_tb;
} kaslr_regions[] = {
- { &page_offset_base, 1 << (__PHYSICAL_MASK_SHIFT - TB_SHIFT) /* Maximum */ },
+ { &page_offset_base, 0 },
{ &vmalloc_base, VMALLOC_SIZE_TB },
{ &vmemmap_base, 1 },
};
@@ -106,6 +106,8 @@ void __init kernel_randomize_memory(void)
if (!kaslr_memory_enabled())
return;

+ kaslr_regions[0].size_tb = 1 << (__PHYSICAL_MASK_SHIFT - TB_SHIFT);
+
/*
* Update Physical memory mapping to available and
* add padding if needed (especially for memory hotplug support).
--
2.14.1
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