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From: steve.capper@arm.com (Steve Capper)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3 2/8] arm64: mm: Flip kernel VA space
Date: Thu, 10 May 2018 17:23:41 +0100	[thread overview]
Message-ID: <20180510162347.3858-3-steve.capper@arm.com> (raw)
In-Reply-To: <20180510162347.3858-1-steve.capper@arm.com>

Put the direct linear map in the lower addresses of the kernel VA range
and everything else in the higher ranges.

This allows us to make room for an inline KASAN shadow that operates
under both 48 and 52 bit kernel VA sizes. For example with a 52-bit VA,
if KASAN_SHADOW_END < 0xFFF8000000000000 (it is in the lower addresses
of the kernel VA range), this will be below the start of the minimum
48-bit kernel VA address of 0xFFFF000000000000.

We need to adjust:
 *) KASAN shadow region placement logic,
 *) KASAN_SHADOW_OFFSET computation logic,
 *) virt_to_phys, phys_to_virt checks,
 *) page table dumper.

These are all small changes, that need to take place atomically, so they
are bundled into this commit.

Signed-off-by: Steve Capper <steve.capper@arm.com>
---
 arch/arm64/Makefile              |  2 +-
 arch/arm64/include/asm/memory.h  | 10 +++++-----
 arch/arm64/include/asm/pgtable.h |  2 +-
 arch/arm64/mm/dump.c             |  8 ++++----
 arch/arm64/mm/init.c             |  9 +--------
 arch/arm64/mm/kasan_init.c       |  4 ++--
 arch/arm64/mm/mmu.c              |  4 ++--
 7 files changed, 16 insertions(+), 23 deletions(-)

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 87f7d2f9f17c..2785f34aa790 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -101,7 +101,7 @@ endif
 # in 32-bit arithmetic
 KASAN_SHADOW_SCALE_SHIFT := 3
 KASAN_SHADOW_OFFSET := $(shell printf "0x%08x00000000\n" $$(( \
-	(0xffffffff & (-1 << ($(CONFIG_ARM64_VA_BITS) - 32))) \
+	(0xffffffff & (-1 << ($(CONFIG_ARM64_VA_BITS) - 1 - 32))) \
 	+ (1 << ($(CONFIG_ARM64_VA_BITS) - 32 - $(KASAN_SHADOW_SCALE_SHIFT))) \
 	- (1 << (64 - 32 - $(KASAN_SHADOW_SCALE_SHIFT))) )) )
 
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index c5617cbbf1ff..f0478617db32 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -58,15 +58,15 @@
  */
 #define VA_BITS			(CONFIG_ARM64_VA_BITS)
 #define VA_START		(UL(0xffffffffffffffff) - \
-	(UL(1) << VA_BITS) + 1)
-#define PAGE_OFFSET		(UL(0xffffffffffffffff) - \
 	(UL(1) << (VA_BITS - 1)) + 1)
-#define PAGE_OFFSET_END		(~0UL)
+#define PAGE_OFFSET		(UL(0xffffffffffffffff) - \
+	(UL(1) << VA_BITS) + 1)
+#define PAGE_OFFSET_END		(VA_START)
 #define KIMAGE_VADDR		(MODULES_END)
 #define MODULES_END		(MODULES_VADDR + MODULES_VSIZE)
 #define MODULES_VADDR		(VA_START + KASAN_SHADOW_SIZE)
 #define MODULES_VSIZE		(SZ_128M)
-#define VMEMMAP_START		(PAGE_OFFSET - VMEMMAP_SIZE)
+#define VMEMMAP_START		(-VMEMMAP_SIZE)
 #define PCI_IO_END		(VMEMMAP_START - SZ_2M)
 #define PCI_IO_START		(PCI_IO_END - PCI_IO_SIZE)
 #define FIXADDR_TOP		(PCI_IO_START - SZ_2M)
@@ -218,7 +218,7 @@ static inline unsigned long kaslr_offset(void)
  * space. Testing the top bit for the start of the region is a
  * sufficient check.
  */
-#define __is_lm_address(addr)	(!!((addr) & BIT(VA_BITS - 1)))
+#define __is_lm_address(addr)	(!((addr) & BIT(VA_BITS - 1)))
 
 #define __lm_to_phys(addr)	(((addr) & ~PAGE_OFFSET) + PHYS_OFFSET)
 #define __kimg_to_phys(addr)	((addr) - kimage_voffset)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 7c4c8f318ba9..31e26f3ab078 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -31,7 +31,7 @@
  *	and fixed mappings
  */
 #define VMALLOC_START		(MODULES_END)
-#define VMALLOC_END		(PAGE_OFFSET - PUD_SIZE - VMEMMAP_SIZE - SZ_64K)
+#define VMALLOC_END		(- PUD_SIZE - VMEMMAP_SIZE - SZ_64K)
 
 #define vmemmap			((struct page *)VMEMMAP_START - (memstart_addr >> PAGE_SHIFT))
 
diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
index 65dfc8571bf8..76e8857b2baf 100644
--- a/arch/arm64/mm/dump.c
+++ b/arch/arm64/mm/dump.c
@@ -30,6 +30,8 @@
 #include <asm/ptdump.h>
 
 static const struct addr_marker address_markers[] = {
+	{ PAGE_OFFSET,			"Linear Mapping start" },
+	{ VA_START,			"Linear Mapping end" },
 #ifdef CONFIG_KASAN
 	{ KASAN_SHADOW_START,		"Kasan shadow start" },
 	{ KASAN_SHADOW_END,		"Kasan shadow end" },
@@ -43,10 +45,8 @@ static const struct addr_marker address_markers[] = {
 	{ PCI_IO_START,			"PCI I/O start" },
 	{ PCI_IO_END,			"PCI I/O end" },
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
-	{ VMEMMAP_START,		"vmemmap start" },
-	{ VMEMMAP_START + VMEMMAP_SIZE,	"vmemmap end" },
+	{ VMEMMAP_START,		"vmemmap" },
 #endif
-	{ PAGE_OFFSET,			"Linear Mapping" },
 	{ -1,				NULL },
 };
 
@@ -381,7 +381,7 @@ static void ptdump_initialize(void)
 static struct ptdump_info kernel_ptdump_info = {
 	.mm		= &init_mm,
 	.markers	= address_markers,
-	.base_addr	= VA_START,
+	.base_addr	= PAGE_OFFSET,
 };
 
 void ptdump_check_wx(void)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 9f3c47acf8ff..efb7e860f99f 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -361,7 +361,7 @@ static void __init fdt_enforce_memory_region(void)
 
 void __init arm64_memblock_init(void)
 {
-	const s64 linear_region_size = -(s64)PAGE_OFFSET;
+	const s64 linear_region_size = BIT(VA_BITS - 1);
 
 	/* Handle linux,usable-memory-range property */
 	fdt_enforce_memory_region();
@@ -370,13 +370,6 @@ void __init arm64_memblock_init(void)
 	memblock_remove(1ULL << PHYS_MASK_SHIFT, ULLONG_MAX);
 
 	/*
-	 * Ensure that the linear region takes up exactly half of the kernel
-	 * virtual address space. This way, we can distinguish a linear address
-	 * from a kernel/module/vmalloc address by testing a single bit.
-	 */
-	BUILD_BUG_ON(linear_region_size != BIT(VA_BITS - 1));
-
-	/*
 	 * Select a suitable value for the base of physical memory.
 	 */
 	memstart_addr = round_down(memblock_start_of_DRAM(),
diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index 12145874c02b..7571e3e6e0f0 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c
@@ -206,10 +206,10 @@ void __init kasan_init(void)
 	kasan_map_populate(kimg_shadow_start, kimg_shadow_end,
 			   early_pfn_to_nid(virt_to_pfn(lm_alias(_text))));
 
-	kasan_populate_zero_shadow((void *)KASAN_SHADOW_START,
+	kasan_populate_zero_shadow(kasan_mem_to_shadow((void *) VA_START),
 				   (void *)mod_shadow_start);
 	kasan_populate_zero_shadow((void *)kimg_shadow_end,
-				   kasan_mem_to_shadow((void *)PAGE_OFFSET));
+				   (void *)KASAN_SHADOW_END);
 
 	if (kimg_shadow_start > mod_shadow_end)
 		kasan_populate_zero_shadow((void *)mod_shadow_end,
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 2dbb2c9f1ec1..12ce780fcef4 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -368,7 +368,7 @@ static phys_addr_t pgd_pgtable_alloc(void)
 static void __init create_mapping_noalloc(phys_addr_t phys, unsigned long virt,
 				  phys_addr_t size, pgprot_t prot)
 {
-	if (virt < VMALLOC_START) {
+	if ((virt >= VA_START) && (virt < VMALLOC_START)) {
 		pr_warn("BUG: not creating mapping for %pa@0x%016lx - outside kernel range\n",
 			&phys, virt);
 		return;
@@ -395,7 +395,7 @@ void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
 static void update_mapping_prot(phys_addr_t phys, unsigned long virt,
 				phys_addr_t size, pgprot_t prot)
 {
-	if (virt < VMALLOC_START) {
+	if ((virt >= VA_START) && (virt < VMALLOC_START)) {
 		pr_warn("BUG: not updating mapping for %pa@0x%016lx - outside kernel range\n",
 			&phys, virt);
 		return;
-- 
2.11.0

  parent reply	other threads:[~2018-05-10 16:23 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-10 16:23 [PATCH V3 0/8] 52-bit kernel VAs for arm64 Steve Capper
2018-05-10 16:23 ` [PATCH v3 1/8] arm/arm64: KVM: Formalise end of direct linear map Steve Capper
2018-05-10 17:11   ` Marc Zyngier
2018-05-11  9:46     ` Steve Capper
2018-05-11 10:00       ` Steve Capper
2018-05-10 16:23 ` Steve Capper [this message]
2018-05-10 16:23 ` [PATCH v3 3/8] arm64: kasan: Switch to using KASAN_SHADOW_OFFSET Steve Capper
2018-05-10 16:23 ` [PATCH v3 4/8] arm64: mm: Replace fixed map BUILD_BUG_ON's with BUG_ON's Steve Capper
2018-05-10 16:23 ` [PATCH v3 5/8] arm64: dump: Make kernel page table dumper dynamic again Steve Capper
2018-05-10 16:23 ` [PATCH v3 6/8] arm64: module-plts: Extend veneer to address 52-bit VAs Steve Capper
2018-05-10 22:01   ` Ard Biesheuvel
2018-05-11 10:11     ` Steve Capper
2018-05-14 10:31       ` Ard Biesheuvel
2018-05-10 16:23 ` [PATCH v3 7/8] arm64: mm: Make VA space size variable Steve Capper
2018-05-10 16:23 ` [PATCH v3 8/8] arm64: mm: Add 48/52-bit kernel VA support Steve Capper
2018-09-07  6:25 ` [PATCH V3 0/8] 52-bit kernel VAs for arm64 Jon Masters
2018-09-07 14:13   ` Steve Capper
2018-09-07 19:45     ` Jon Masters

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