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From: Steve Capper <steve.capper@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: crecklin@redhat.com, Steve Capper <steve.capper@arm.com>,
	marc.zyngier@arm.com, catalin.marinas@arm.com,
	ard.biesheuvel@linaro.org, will.deacon@arm.com
Subject: [PATCH 2/9] arm64: mm: Flip kernel VA space
Date: Mon, 18 Feb 2019 17:02:38 +0000	[thread overview]
Message-ID: <20190218170245.14915-3-steve.capper@arm.com> (raw)
In-Reply-To: <20190218170245.14915-1-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       |  6 +++---
 arch/arm64/mm/mmu.c              |  4 ++--
 7 files changed, 17 insertions(+), 24 deletions(-)

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index b025304bde46..2dad2ae6b181 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -115,7 +115,7 @@ KBUILD_AFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT)
 #				 - (1 << (64 - KASAN_SHADOW_SCALE_SHIFT))
 # in 32-bit arithmetic
 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 617071dbad06..46a7aba44e9b 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -49,10 +49,10 @@
  */
 #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 BPF_JIT_REGION_START	(VA_START + KASAN_SHADOW_SIZE)
 #define BPF_JIT_REGION_SIZE	(SZ_128M)
@@ -60,7 +60,7 @@
 #define MODULES_END		(MODULES_VADDR + MODULES_VSIZE)
 #define MODULES_VADDR		(BPF_JIT_REGION_END)
 #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)
@@ -243,7 +243,7 @@ extern u64			vabits_user;
  * 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 de70c1eabf33..766def2ed788 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -32,7 +32,7 @@
  *	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 99bb8facb5cb..3dd9b884bd39 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 },
 };
 
@@ -380,7 +380,7 @@ 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 7205a9085b4d..0574e17fd28d 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -354,7 +354,7 @@ 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();
@@ -362,13 +362,6 @@ void __init arm64_memblock_init(void)
 	/* Remove memory above our supported physical address size */
 	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.
 	 */
diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index 4b55b15707a3..ee5ec343d009 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c
@@ -219,10 +219,10 @@ 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_early_shadow((void *)KASAN_SHADOW_START,
-				    (void *)mod_shadow_start);
+	kasan_populate_early_shadow(kasan_mem_to_shadow((void *) VA_START),
+				   (void *)mod_shadow_start);
 	kasan_populate_early_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_early_shadow((void *)mod_shadow_end,
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index b6f5aa52ac67..7401a8481f78 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -389,7 +389,7 @@ 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 at 0x%016lx - outside kernel range\n",
 			&phys, virt);
 		return;
@@ -416,7 +416,7 @@ 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 at 0x%016lx - outside kernel range\n",
 			&phys, virt);
 		return;
-- 
2.20.1


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  parent reply	other threads:[~2019-02-18 17:06 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-18 17:02 [PATCH 0/9] 52-bit kernel + user VAs Steve Capper
2019-02-18 17:02 ` [PATCH 1/9] arm/arm64: KVM: Formalise end of direct linear map Steve Capper
2019-02-18 17:02 ` Steve Capper [this message]
2019-04-03 11:44   ` [PATCH 2/9] arm64: mm: Flip kernel VA space Bhupesh Sharma
2019-02-18 17:02 ` [PATCH 3/9] arm64: kasan: Switch to using KASAN_SHADOW_OFFSET Steve Capper
2019-02-18 17:02 ` [PATCH 4/9] arm64: mm: Replace fixed map BUILD_BUG_ON's with BUG_ON's Steve Capper
2019-02-18 17:02 ` [PATCH 5/9] arm64: dump: Make kernel page table dumper dynamic again Steve Capper
2019-02-18 17:02 ` [PATCH 6/9] arm64: mm: Introduce VA_BITS_MIN Steve Capper
2019-02-18 17:02 ` [PATCH 7/9] arm64: mm: Introduce VA_BITS_ACTUAL Steve Capper
2019-02-18 17:02 ` [PATCH 8/9] arm64: mm: Logic to make offset_ttbr1 conditional Steve Capper
2019-04-03 11:26   ` Bhupesh Sharma
2019-02-18 17:02 ` [PATCH 9/9] arm64: mm: Introduce 52-bit Kernel VAs Steve Capper
2019-03-25 18:17   ` Catalin Marinas
2019-02-19 12:13 ` [PATCH 0/9] 52-bit kernel + user VAs Ard Biesheuvel
2019-02-19 12:48   ` Will Deacon
2019-02-19 12:51     ` Ard Biesheuvel
2019-02-19 13:01       ` Will Deacon
2019-02-19 13:15         ` Ard Biesheuvel
2019-02-19 13:56           ` Steve Capper
2019-02-19 16:18             ` Ard Biesheuvel
2019-02-26 17:30               ` Steve Capper
2019-02-26 20:17                 ` Ard Biesheuvel
2019-02-28 10:35                   ` Steve Capper
2019-02-28 11:22                     ` Ard Biesheuvel
2019-02-28 11:45                       ` Steve Capper
2019-03-25 18:38                       ` Catalin Marinas
2019-03-25 20:32                         ` Ard Biesheuvel
2019-04-03  8:09 ` Bhupesh Sharma
2019-05-03 14:57   ` Steve Capper

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