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Subject[PATCH 8/9] x86/mm: Make __VIRTUAL_MASK_SHIFT dynamic
Date
For boot-time switching between paging modes, we need to be able to
adjust virtual mask shifts.

The change doesn't affect the kernel image size much:

text data bss dec hex filename
8628892 4734340 1368064 14731296 e0c820 vmlinux.before
8628966 4734340 1368064 14731370 e0c86a vmlinux.after

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 | 2 +-
arch/x86/mm/dump_pagetables.c | 12 ++++++++++--
arch/x86/mm/kaslr.c | 4 +++-
4 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index cd216c9431e1..1608b13a0b36 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -260,8 +260,20 @@ GLOBAL(entry_SYSCALL_64_after_hwframe)
* 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 d54a3d5b5b3b..fa7dc7cd8c19 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -56,7 +56,7 @@
#define __PHYSICAL_MASK_SHIFT 52

#ifdef CONFIG_X86_5LEVEL
-#define __VIRTUAL_MASK_SHIFT 56
+#define __VIRTUAL_MASK_SHIFT (pgtable_l5_enabled ? 56 : 47)
#else
#define __VIRTUAL_MASK_SHIFT 47
#endif
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 420058b05d39..9efee6f464ab 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -85,8 +85,12 @@ static struct addr_marker address_markers[] = {
[VMALLOC_START_NR] = { 0UL, "vmalloc() Area" },
[VMEMMAP_START_NR] = { 0UL, "Vmemmap" },
#ifdef CONFIG_KASAN
- [KASAN_SHADOW_START_NR] = { KASAN_SHADOW_START, "KASAN shadow" },
- [KASAN_SHADOW_END_NR] = { KASAN_SHADOW_END, "KASAN shadow end" },
+ /*
+ * These fields get initialized with the (dynamic)
+ * KASAN_SHADOW_{START,END} values in pt_dump_init().
+ */
+ [KASAN_SHADOW_START_NR] = { 0UL, "KASAN shadow" },
+ [KASAN_SHADOW_END_NR] = { 0UL, "KASAN shadow end" },
#endif
#ifdef CONFIG_MODIFY_LDT_SYSCALL
[LDT_NR] = { 0UL, "LDT remap" },
@@ -571,6 +575,10 @@ static int __init pt_dump_init(void)
#ifdef CONFIG_MODIFY_LDT_SYSCALL
address_markers[LDT_NR].start_address = LDT_BASE_ADDR;
#endif
+#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 515b98a8ccee..d079878c6cbc 100644
--- a/arch/x86/mm/kaslr.c
+++ b/arch/x86/mm/kaslr.c
@@ -52,7 +52,7 @@ 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 },
};
@@ -93,6 +93,8 @@ 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).
--
2.15.1
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