[PATCH V4 0/6] 52-bit userspace VAs

[PATCH V4 0/6] 52-bit userspace VAs

[Steve Capper]

This patch series brings support for 52-bit userspace VAs to systems that
have ARMv8.2-LVA and are running with a 48-bit VA_BITS and a 64KB
PAGE_SIZE.

If no hardware support is present, the kernel runs with a 48-bit VA space
for userspace.

Userspace can exploit this feature by providing an address hint to mmap
where addr[51:48] != 0. Otherwise all the VA mappings will behave in the
same way as a 48-bit VA system (this is to maintain compatibility with
software that assumes the maximum VA size on arm64 is 48-bit).

This patch series applies to 4.20-rc1.

Testing was in a model with Trusted Firmware and UEFI for boot.

Changed in V4, pgd_index changes dropped in favour of offsetting the
ttbr1. This is performed in a new patch, #4.

Changed in V3, COMPAT fixes added (and tested with 32-bit userspace code).
Extra patch added to allow forcing all userspace allocations to come from
52-bits (to allow for debugging and testing).

The major change to V2 of the series is that mm/mmap.c is altered in the
first patch of the series (rather than copied over to arch/arm64).


Steve Capper (6):
  mm: mmap: Allow for "high" userspace addresses
  arm64: mm: Introduce DEFAULT_MAP_WINDOW
  arm64: mm: Define arch_get_mmap_end, arch_get_mmap_base
  arm64: mm: Offset TTBR1 to allow 52-bit PTRS_PER_PGD
  arm64: mm: introduce 52-bit userspace support
  arm64: mm: Allow forcing all userspace addresses to 52-bit

 arch/arm64/Kconfig                      | 17 ++++++++++++
 arch/arm64/include/asm/asm-uaccess.h    |  4 +++
 arch/arm64/include/asm/assembler.h      | 30 ++++++++++++++++++---
 arch/arm64/include/asm/elf.h            |  4 +++
 arch/arm64/include/asm/mmu_context.h    |  3 +++
 arch/arm64/include/asm/pgtable-hwdef.h  |  9 +++++++
 arch/arm64/include/asm/processor.h      | 36 ++++++++++++++++++++-----
 arch/arm64/include/asm/uaccess.h        |  4 +++
 arch/arm64/kernel/head.S                | 14 ++++++++++
 arch/arm64/kernel/hibernate-asm.S       |  1 +
 arch/arm64/mm/fault.c                   |  2 +-
 arch/arm64/mm/init.c                    |  2 +-
 arch/arm64/mm/mmu.c                     |  1 +
 arch/arm64/mm/proc.S                    | 14 +++++++++-
 drivers/firmware/efi/arm-runtime.c      |  2 +-
 drivers/firmware/efi/libstub/arm-stub.c |  2 +-
 mm/mmap.c                               | 25 ++++++++++++-----
 17 files changed, 148 insertions(+), 22 deletions(-)

-- 
2.19.2

[PATCH V4 0/6] 52-bit userspace VAs

[Steve Capper]

This patch series brings support for 52-bit userspace VAs to systems that
have ARMv8.2-LVA and are running with a 48-bit VA_BITS and a 64KB
PAGE_SIZE.

If no hardware support is present, the kernel runs with a 48-bit VA space
for userspace.

Userspace can exploit this feature by providing an address hint to mmap
where addr[51:48] != 0. Otherwise all the VA mappings will behave in the
same way as a 48-bit VA system (this is to maintain compatibility with
software that assumes the maximum VA size on arm64 is 48-bit).

This patch series applies to 4.20-rc1.

Testing was in a model with Trusted Firmware and UEFI for boot.

Changed in V4, pgd_index changes dropped in favour of offsetting the
ttbr1. This is performed in a new patch, #4.

Changed in V3, COMPAT fixes added (and tested with 32-bit userspace code).
Extra patch added to allow forcing all userspace allocations to come from
52-bits (to allow for debugging and testing).

The major change to V2 of the series is that mm/mmap.c is altered in the
first patch of the series (rather than copied over to arch/arm64).


Steve Capper (6):
  mm: mmap: Allow for "high" userspace addresses
  arm64: mm: Introduce DEFAULT_MAP_WINDOW
  arm64: mm: Define arch_get_mmap_end, arch_get_mmap_base
  arm64: mm: Offset TTBR1 to allow 52-bit PTRS_PER_PGD
  arm64: mm: introduce 52-bit userspace support
  arm64: mm: Allow forcing all userspace addresses to 52-bit

 arch/arm64/Kconfig                      | 17 ++++++++++++
 arch/arm64/include/asm/asm-uaccess.h    |  4 +++
 arch/arm64/include/asm/assembler.h      | 30 ++++++++++++++++++---
 arch/arm64/include/asm/elf.h            |  4 +++
 arch/arm64/include/asm/mmu_context.h    |  3 +++
 arch/arm64/include/asm/pgtable-hwdef.h  |  9 +++++++
 arch/arm64/include/asm/processor.h      | 36 ++++++++++++++++++++-----
 arch/arm64/include/asm/uaccess.h        |  4 +++
 arch/arm64/kernel/head.S                | 14 ++++++++++
 arch/arm64/kernel/hibernate-asm.S       |  1 +
 arch/arm64/mm/fault.c                   |  2 +-
 arch/arm64/mm/init.c                    |  2 +-
 arch/arm64/mm/mmu.c                     |  1 +
 arch/arm64/mm/proc.S                    | 14 +++++++++-
 drivers/firmware/efi/arm-runtime.c      |  2 +-
 drivers/firmware/efi/libstub/arm-stub.c |  2 +-
 mm/mmap.c                               | 25 ++++++++++++-----
 17 files changed, 148 insertions(+), 22 deletions(-)

-- 
2.19.2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH V4 1/6] mm: mmap: Allow for "high" userspace addresses

[Steve Capper]

This patch adds support for "high" userspace addresses that are
optionally supported on the system and have to be requested via a hint
mechanism ("high" addr parameter to mmap).

Architectures such as powerpc and x86 achieve this by making changes to
their architectural versions of arch_get_unmapped_* functions. However,
on arm64 we use the generic versions of these functions.

Rather than duplicate the generic arch_get_unmapped_* implementations
for arm64, this patch instead introduces two architectural helper macros
and applies them to arch_get_unmapped_*:
 arch_get_mmap_end(addr) - get mmap upper limit depending on addr hint
 arch_get_mmap_base(addr, base) - get mmap_base depending on addr hint

If these macros are not defined in architectural code then they default
to (TASK_SIZE) and (base) so should not introduce any behavioural
changes to architectures that do not define them.

Signed-off-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>

---

Changed in V4, added Catalin's reviewed by

Changed in V3, commit log cleared up, explanation given for why core
code change over just architectural change
---
 mm/mmap.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 6c04292e16a7..7bb64381e77c 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2066,6 +2066,15 @@ unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
 	return gap_end;
 }
 
+
+#ifndef arch_get_mmap_end
+#define arch_get_mmap_end(addr)	(TASK_SIZE)
+#endif
+
+#ifndef arch_get_mmap_base
+#define arch_get_mmap_base(addr, base) (base)
+#endif
+
 /* Get an address range which is currently unmapped.
  * For shmat() with addr=0.
  *
@@ -2085,8 +2094,9 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma, *prev;
 	struct vm_unmapped_area_info info;
+	const unsigned long mmap_end = arch_get_mmap_end(addr);
 
-	if (len > TASK_SIZE - mmap_min_addr)
+	if (len > mmap_end - mmap_min_addr)
 		return -ENOMEM;
 
 	if (flags & MAP_FIXED)
@@ -2095,7 +2105,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	if (addr) {
 		addr = PAGE_ALIGN(addr);
 		vma = find_vma_prev(mm, addr, &prev);
-		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+		if (mmap_end - len >= addr && addr >= mmap_min_addr &&
 		    (!vma || addr + len <= vm_start_gap(vma)) &&
 		    (!prev || addr >= vm_end_gap(prev)))
 			return addr;
@@ -2104,7 +2114,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	info.flags = 0;
 	info.length = len;
 	info.low_limit = mm->mmap_base;
-	info.high_limit = TASK_SIZE;
+	info.high_limit = mmap_end;
 	info.align_mask = 0;
 	return vm_unmapped_area(&info);
 }
@@ -2124,9 +2134,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	struct mm_struct *mm = current->mm;
 	unsigned long addr = addr0;
 	struct vm_unmapped_area_info info;
+	const unsigned long mmap_end = arch_get_mmap_end(addr);
 
 	/* requested length too big for entire address space */
-	if (len > TASK_SIZE - mmap_min_addr)
+	if (len > mmap_end - mmap_min_addr)
 		return -ENOMEM;
 
 	if (flags & MAP_FIXED)
@@ -2136,7 +2147,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	if (addr) {
 		addr = PAGE_ALIGN(addr);
 		vma = find_vma_prev(mm, addr, &prev);
-		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+		if (mmap_end - len >= addr && addr >= mmap_min_addr &&
 				(!vma || addr + len <= vm_start_gap(vma)) &&
 				(!prev || addr >= vm_end_gap(prev)))
 			return addr;
@@ -2145,7 +2156,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 	info.length = len;
 	info.low_limit = max(PAGE_SIZE, mmap_min_addr);
-	info.high_limit = mm->mmap_base;
+	info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
 	info.align_mask = 0;
 	addr = vm_unmapped_area(&info);
 
@@ -2159,7 +2170,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 		VM_BUG_ON(addr != -ENOMEM);
 		info.flags = 0;
 		info.low_limit = TASK_UNMAPPED_BASE;
-		info.high_limit = TASK_SIZE;
+		info.high_limit = mmap_end;
 		addr = vm_unmapped_area(&info);
 	}
 
-- 
2.19.2

[PATCH V4 1/6] mm: mmap: Allow for "high" userspace addresses

[Steve Capper]

This patch adds support for "high" userspace addresses that are
optionally supported on the system and have to be requested via a hint
mechanism ("high" addr parameter to mmap).

Architectures such as powerpc and x86 achieve this by making changes to
their architectural versions of arch_get_unmapped_* functions. However,
on arm64 we use the generic versions of these functions.

Rather than duplicate the generic arch_get_unmapped_* implementations
for arm64, this patch instead introduces two architectural helper macros
and applies them to arch_get_unmapped_*:
 arch_get_mmap_end(addr) - get mmap upper limit depending on addr hint
 arch_get_mmap_base(addr, base) - get mmap_base depending on addr hint

If these macros are not defined in architectural code then they default
to (TASK_SIZE) and (base) so should not introduce any behavioural
changes to architectures that do not define them.

Signed-off-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>

---

Changed in V4, added Catalin's reviewed by

Changed in V3, commit log cleared up, explanation given for why core
code change over just architectural change
---
 mm/mmap.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 6c04292e16a7..7bb64381e77c 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2066,6 +2066,15 @@ unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
 	return gap_end;
 }
 
+
+#ifndef arch_get_mmap_end
+#define arch_get_mmap_end(addr)	(TASK_SIZE)
+#endif
+
+#ifndef arch_get_mmap_base
+#define arch_get_mmap_base(addr, base) (base)
+#endif
+
 /* Get an address range which is currently unmapped.
  * For shmat() with addr=0.
  *
@@ -2085,8 +2094,9 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma, *prev;
 	struct vm_unmapped_area_info info;
+	const unsigned long mmap_end = arch_get_mmap_end(addr);
 
-	if (len > TASK_SIZE - mmap_min_addr)
+	if (len > mmap_end - mmap_min_addr)
 		return -ENOMEM;
 
 	if (flags & MAP_FIXED)
@@ -2095,7 +2105,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	if (addr) {
 		addr = PAGE_ALIGN(addr);
 		vma = find_vma_prev(mm, addr, &prev);
-		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+		if (mmap_end - len >= addr && addr >= mmap_min_addr &&
 		    (!vma || addr + len <= vm_start_gap(vma)) &&
 		    (!prev || addr >= vm_end_gap(prev)))
 			return addr;
@@ -2104,7 +2114,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	info.flags = 0;
 	info.length = len;
 	info.low_limit = mm->mmap_base;
-	info.high_limit = TASK_SIZE;
+	info.high_limit = mmap_end;
 	info.align_mask = 0;
 	return vm_unmapped_area(&info);
 }
@@ -2124,9 +2134,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	struct mm_struct *mm = current->mm;
 	unsigned long addr = addr0;
 	struct vm_unmapped_area_info info;
+	const unsigned long mmap_end = arch_get_mmap_end(addr);
 
 	/* requested length too big for entire address space */
-	if (len > TASK_SIZE - mmap_min_addr)
+	if (len > mmap_end - mmap_min_addr)
 		return -ENOMEM;
 
 	if (flags & MAP_FIXED)
@@ -2136,7 +2147,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	if (addr) {
 		addr = PAGE_ALIGN(addr);
 		vma = find_vma_prev(mm, addr, &prev);
-		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+		if (mmap_end - len >= addr && addr >= mmap_min_addr &&
 				(!vma || addr + len <= vm_start_gap(vma)) &&
 				(!prev || addr >= vm_end_gap(prev)))
 			return addr;
@@ -2145,7 +2156,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 	info.length = len;
 	info.low_limit = max(PAGE_SIZE, mmap_min_addr);
-	info.high_limit = mm->mmap_base;
+	info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
 	info.align_mask = 0;
 	addr = vm_unmapped_area(&info);
 
@@ -2159,7 +2170,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 		VM_BUG_ON(addr != -ENOMEM);
 		info.flags = 0;
 		info.low_limit = TASK_UNMAPPED_BASE;
-		info.high_limit = TASK_SIZE;
+		info.high_limit = mmap_end;
 		addr = vm_unmapped_area(&info);
 	}
 
-- 
2.19.2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH V4 2/6] arm64: mm: Introduce DEFAULT_MAP_WINDOW

[Steve Capper]

We wish to introduce a 52-bit virtual address space for userspace but
maintain compatibility with software that assumes the maximum VA space
size is 48 bit.

In order to achieve this, on 52-bit VA systems, we make mmap behave as
if it were running on a 48-bit VA system (unless userspace explicitly
requests a VA where addr[51:48] != 0).

On a system running a 52-bit userspace we need TASK_SIZE to represent
the 52-bit limit as it is used in various places to distinguish between
kernelspace and userspace addresses.

Thus we need a new limit for mmap, stack, ELF loader and EFI (which uses
TTBR0) to represent the non-extended VA space.

This patch introduces DEFAULT_MAP_WINDOW and DEFAULT_MAP_WINDOW_64 and
switches the appropriate logic to use that instead of TASK_SIZE.

Signed-off-by: Steve Capper <steve.capper@arm.com>

---

Changed in V3: corrections to allow COMPAT 32-bit EL0 mode to work
---
 arch/arm64/include/asm/elf.h            |  2 +-
 arch/arm64/include/asm/processor.h      | 10 ++++++++--
 arch/arm64/mm/init.c                    |  2 +-
 drivers/firmware/efi/arm-runtime.c      |  2 +-
 drivers/firmware/efi/libstub/arm-stub.c |  2 +-
 5 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 433b9554c6a1..bc9bd9e77d9d 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -117,7 +117,7 @@
  * 64-bit, this is above 4GB to leave the entire 32-bit address
  * space open for things that want to use the area for 32-bit pointers.
  */
-#define ELF_ET_DYN_BASE		(2 * TASK_SIZE_64 / 3)
+#define ELF_ET_DYN_BASE		(2 * DEFAULT_MAP_WINDOW_64 / 3)
 
 #ifndef __ASSEMBLY__
 
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 3e2091708b8e..50586ca6bacb 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -45,19 +45,25 @@
  * TASK_SIZE - the maximum size of a user space task.
  * TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area.
  */
+
+#define DEFAULT_MAP_WINDOW_64	(UL(1) << VA_BITS)
+
 #ifdef CONFIG_COMPAT
 #define TASK_SIZE_32		UL(0x100000000)
 #define TASK_SIZE		(test_thread_flag(TIF_32BIT) ? \
 				TASK_SIZE_32 : TASK_SIZE_64)
 #define TASK_SIZE_OF(tsk)	(test_tsk_thread_flag(tsk, TIF_32BIT) ? \
 				TASK_SIZE_32 : TASK_SIZE_64)
+#define DEFAULT_MAP_WINDOW	(test_thread_flag(TIF_32BIT) ? \
+				TASK_SIZE_32 : DEFAULT_MAP_WINDOW_64)
 #else
 #define TASK_SIZE		TASK_SIZE_64
+#define DEFAULT_MAP_WINDOW	DEFAULT_MAP_WINDOW_64
 #endif /* CONFIG_COMPAT */
 
-#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(TASK_SIZE / 4))
+#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(DEFAULT_MAP_WINDOW / 4))
+#define STACK_TOP_MAX		DEFAULT_MAP_WINDOW_64
 
-#define STACK_TOP_MAX		TASK_SIZE_64
 #ifdef CONFIG_COMPAT
 #define AARCH32_VECTORS_BASE	0xffff0000
 #define STACK_TOP		(test_thread_flag(TIF_32BIT) ? \
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 9d9582cac6c4..7239c103be06 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -609,7 +609,7 @@ void __init mem_init(void)
 	 * detected at build time already.
 	 */
 #ifdef CONFIG_COMPAT
-	BUILD_BUG_ON(TASK_SIZE_32			> TASK_SIZE_64);
+	BUILD_BUG_ON(TASK_SIZE_32 > DEFAULT_MAP_WINDOW_64);
 #endif
 
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c
index 922cfb813109..952cec5b611a 100644
--- a/drivers/firmware/efi/arm-runtime.c
+++ b/drivers/firmware/efi/arm-runtime.c
@@ -38,7 +38,7 @@ static struct ptdump_info efi_ptdump_info = {
 	.mm		= &efi_mm,
 	.markers	= (struct addr_marker[]){
 		{ 0,		"UEFI runtime start" },
-		{ TASK_SIZE_64,	"UEFI runtime end" }
+		{ DEFAULT_MAP_WINDOW_64, "UEFI runtime end" }
 	},
 	.base_addr	= 0,
 };
diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
index 30ac0c975f8a..d1ec7136e3e1 100644
--- a/drivers/firmware/efi/libstub/arm-stub.c
+++ b/drivers/firmware/efi/libstub/arm-stub.c
@@ -33,7 +33,7 @@
 #define EFI_RT_VIRTUAL_SIZE	SZ_512M
 
 #ifdef CONFIG_ARM64
-# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE_64
+# define EFI_RT_VIRTUAL_LIMIT	DEFAULT_MAP_WINDOW_64
 #else
 # define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE
 #endif
-- 
2.19.2

[PATCH V4 2/6] arm64: mm: Introduce DEFAULT_MAP_WINDOW

[Steve Capper]

We wish to introduce a 52-bit virtual address space for userspace but
maintain compatibility with software that assumes the maximum VA space
size is 48 bit.

In order to achieve this, on 52-bit VA systems, we make mmap behave as
if it were running on a 48-bit VA system (unless userspace explicitly
requests a VA where addr[51:48] != 0).

On a system running a 52-bit userspace we need TASK_SIZE to represent
the 52-bit limit as it is used in various places to distinguish between
kernelspace and userspace addresses.

Thus we need a new limit for mmap, stack, ELF loader and EFI (which uses
TTBR0) to represent the non-extended VA space.

This patch introduces DEFAULT_MAP_WINDOW and DEFAULT_MAP_WINDOW_64 and
switches the appropriate logic to use that instead of TASK_SIZE.

Signed-off-by: Steve Capper <steve.capper@arm.com>

---

Changed in V3: corrections to allow COMPAT 32-bit EL0 mode to work
---
 arch/arm64/include/asm/elf.h            |  2 +-
 arch/arm64/include/asm/processor.h      | 10 ++++++++--
 arch/arm64/mm/init.c                    |  2 +-
 drivers/firmware/efi/arm-runtime.c      |  2 +-
 drivers/firmware/efi/libstub/arm-stub.c |  2 +-
 5 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 433b9554c6a1..bc9bd9e77d9d 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -117,7 +117,7 @@
  * 64-bit, this is above 4GB to leave the entire 32-bit address
  * space open for things that want to use the area for 32-bit pointers.
  */
-#define ELF_ET_DYN_BASE		(2 * TASK_SIZE_64 / 3)
+#define ELF_ET_DYN_BASE		(2 * DEFAULT_MAP_WINDOW_64 / 3)
 
 #ifndef __ASSEMBLY__
 
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 3e2091708b8e..50586ca6bacb 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -45,19 +45,25 @@
  * TASK_SIZE - the maximum size of a user space task.
  * TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area.
  */
+
+#define DEFAULT_MAP_WINDOW_64	(UL(1) << VA_BITS)
+
 #ifdef CONFIG_COMPAT
 #define TASK_SIZE_32		UL(0x100000000)
 #define TASK_SIZE		(test_thread_flag(TIF_32BIT) ? \
 				TASK_SIZE_32 : TASK_SIZE_64)
 #define TASK_SIZE_OF(tsk)	(test_tsk_thread_flag(tsk, TIF_32BIT) ? \
 				TASK_SIZE_32 : TASK_SIZE_64)
+#define DEFAULT_MAP_WINDOW	(test_thread_flag(TIF_32BIT) ? \
+				TASK_SIZE_32 : DEFAULT_MAP_WINDOW_64)
 #else
 #define TASK_SIZE		TASK_SIZE_64
+#define DEFAULT_MAP_WINDOW	DEFAULT_MAP_WINDOW_64
 #endif /* CONFIG_COMPAT */
 
-#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(TASK_SIZE / 4))
+#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(DEFAULT_MAP_WINDOW / 4))
+#define STACK_TOP_MAX		DEFAULT_MAP_WINDOW_64
 
-#define STACK_TOP_MAX		TASK_SIZE_64
 #ifdef CONFIG_COMPAT
 #define AARCH32_VECTORS_BASE	0xffff0000
 #define STACK_TOP		(test_thread_flag(TIF_32BIT) ? \
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 9d9582cac6c4..7239c103be06 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -609,7 +609,7 @@ void __init mem_init(void)
 	 * detected at build time already.
 	 */
 #ifdef CONFIG_COMPAT
-	BUILD_BUG_ON(TASK_SIZE_32			> TASK_SIZE_64);
+	BUILD_BUG_ON(TASK_SIZE_32 > DEFAULT_MAP_WINDOW_64);
 #endif
 
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c
index 922cfb813109..952cec5b611a 100644
--- a/drivers/firmware/efi/arm-runtime.c
+++ b/drivers/firmware/efi/arm-runtime.c
@@ -38,7 +38,7 @@ static struct ptdump_info efi_ptdump_info = {
 	.mm		= &efi_mm,
 	.markers	= (struct addr_marker[]){
 		{ 0,		"UEFI runtime start" },
-		{ TASK_SIZE_64,	"UEFI runtime end" }
+		{ DEFAULT_MAP_WINDOW_64, "UEFI runtime end" }
 	},
 	.base_addr	= 0,
 };
diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
index 30ac0c975f8a..d1ec7136e3e1 100644
--- a/drivers/firmware/efi/libstub/arm-stub.c
+++ b/drivers/firmware/efi/libstub/arm-stub.c
@@ -33,7 +33,7 @@
 #define EFI_RT_VIRTUAL_SIZE	SZ_512M
 
 #ifdef CONFIG_ARM64
-# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE_64
+# define EFI_RT_VIRTUAL_LIMIT	DEFAULT_MAP_WINDOW_64
 #else
 # define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE
 #endif
-- 
2.19.2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH V4 2/6] arm64: mm: Introduce DEFAULT_MAP_WINDOW

[Catalin Marinas]

On Wed, Dec 05, 2018 at 04:41:41PM +0000, Steve Capper wrote:
> We wish to introduce a 52-bit virtual address space for userspace but
> maintain compatibility with software that assumes the maximum VA space
> size is 48 bit.
> 
> In order to achieve this, on 52-bit VA systems, we make mmap behave as
> if it were running on a 48-bit VA system (unless userspace explicitly
> requests a VA where addr[51:48] != 0).
> 
> On a system running a 52-bit userspace we need TASK_SIZE to represent
> the 52-bit limit as it is used in various places to distinguish between
> kernelspace and userspace addresses.
> 
> Thus we need a new limit for mmap, stack, ELF loader and EFI (which uses
> TTBR0) to represent the non-extended VA space.
> 
> This patch introduces DEFAULT_MAP_WINDOW and DEFAULT_MAP_WINDOW_64 and
> switches the appropriate logic to use that instead of TASK_SIZE.
> 
> Signed-off-by: Steve Capper <steve.capper@arm.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Re: [PATCH V4 2/6] arm64: mm: Introduce DEFAULT_MAP_WINDOW

[Catalin Marinas]

On Wed, Dec 05, 2018 at 04:41:41PM +0000, Steve Capper wrote:
> We wish to introduce a 52-bit virtual address space for userspace but
> maintain compatibility with software that assumes the maximum VA space
> size is 48 bit.
> 
> In order to achieve this, on 52-bit VA systems, we make mmap behave as
> if it were running on a 48-bit VA system (unless userspace explicitly
> requests a VA where addr[51:48] != 0).
> 
> On a system running a 52-bit userspace we need TASK_SIZE to represent
> the 52-bit limit as it is used in various places to distinguish between
> kernelspace and userspace addresses.
> 
> Thus we need a new limit for mmap, stack, ELF loader and EFI (which uses
> TTBR0) to represent the non-extended VA space.
> 
> This patch introduces DEFAULT_MAP_WINDOW and DEFAULT_MAP_WINDOW_64 and
> switches the appropriate logic to use that instead of TASK_SIZE.
> 
> Signed-off-by: Steve Capper <steve.capper@arm.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH V4 2/6] arm64: mm: Introduce DEFAULT_MAP_WINDOW

[Steve Capper]

On Wed, Dec 05, 2018 at 05:36:52PM +0000, Catalin Marinas wrote:
> On Wed, Dec 05, 2018 at 04:41:41PM +0000, Steve Capper wrote:
> > We wish to introduce a 52-bit virtual address space for userspace but
> > maintain compatibility with software that assumes the maximum VA space
> > size is 48 bit.
> > 
> > In order to achieve this, on 52-bit VA systems, we make mmap behave as
> > if it were running on a 48-bit VA system (unless userspace explicitly
> > requests a VA where addr[51:48] != 0).
> > 
> > On a system running a 52-bit userspace we need TASK_SIZE to represent
> > the 52-bit limit as it is used in various places to distinguish between
> > kernelspace and userspace addresses.
> > 
> > Thus we need a new limit for mmap, stack, ELF loader and EFI (which uses
> > TTBR0) to represent the non-extended VA space.
> > 
> > This patch introduces DEFAULT_MAP_WINDOW and DEFAULT_MAP_WINDOW_64 and
> > switches the appropriate logic to use that instead of TASK_SIZE.
> > 
> > Signed-off-by: Steve Capper <steve.capper@arm.com>
> 
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Thanks!

Re: [PATCH V4 2/6] arm64: mm: Introduce DEFAULT_MAP_WINDOW

[Steve Capper]

On Wed, Dec 05, 2018 at 05:36:52PM +0000, Catalin Marinas wrote:
> On Wed, Dec 05, 2018 at 04:41:41PM +0000, Steve Capper wrote:
> > We wish to introduce a 52-bit virtual address space for userspace but
> > maintain compatibility with software that assumes the maximum VA space
> > size is 48 bit.
> > 
> > In order to achieve this, on 52-bit VA systems, we make mmap behave as
> > if it were running on a 48-bit VA system (unless userspace explicitly
> > requests a VA where addr[51:48] != 0).
> > 
> > On a system running a 52-bit userspace we need TASK_SIZE to represent
> > the 52-bit limit as it is used in various places to distinguish between
> > kernelspace and userspace addresses.
> > 
> > Thus we need a new limit for mmap, stack, ELF loader and EFI (which uses
> > TTBR0) to represent the non-extended VA space.
> > 
> > This patch introduces DEFAULT_MAP_WINDOW and DEFAULT_MAP_WINDOW_64 and
> > switches the appropriate logic to use that instead of TASK_SIZE.
> > 
> > Signed-off-by: Steve Capper <steve.capper@arm.com>
> 
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Thanks!

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH V4 3/6] arm64: mm: Define arch_get_mmap_end, arch_get_mmap_base

[Steve Capper]

Now that we have DEFAULT_MAP_WINDOW defined, we can arch_get_mmap_end
and arch_get_mmap_base helpers to allow for high addresses in mmap.

Signed-off-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm64/include/asm/processor.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 50586ca6bacb..fe95fd8b065e 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -72,6 +72,13 @@
 #define STACK_TOP		STACK_TOP_MAX
 #endif /* CONFIG_COMPAT */
 
+#define arch_get_mmap_end(addr) ((addr > DEFAULT_MAP_WINDOW) ? TASK_SIZE :\
+				DEFAULT_MAP_WINDOW)
+
+#define arch_get_mmap_base(addr, base) ((addr > DEFAULT_MAP_WINDOW) ? \
+					base + TASK_SIZE - DEFAULT_MAP_WINDOW :\
+					base)
+
 extern phys_addr_t arm64_dma_phys_limit;
 #define ARCH_LOW_ADDRESS_LIMIT	(arm64_dma_phys_limit - 1)
 
-- 
2.19.2

[PATCH V4 3/6] arm64: mm: Define arch_get_mmap_end, arch_get_mmap_base

[Steve Capper]

Now that we have DEFAULT_MAP_WINDOW defined, we can arch_get_mmap_end
and arch_get_mmap_base helpers to allow for high addresses in mmap.

Signed-off-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm64/include/asm/processor.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 50586ca6bacb..fe95fd8b065e 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -72,6 +72,13 @@
 #define STACK_TOP		STACK_TOP_MAX
 #endif /* CONFIG_COMPAT */
 
+#define arch_get_mmap_end(addr) ((addr > DEFAULT_MAP_WINDOW) ? TASK_SIZE :\
+				DEFAULT_MAP_WINDOW)
+
+#define arch_get_mmap_base(addr, base) ((addr > DEFAULT_MAP_WINDOW) ? \
+					base + TASK_SIZE - DEFAULT_MAP_WINDOW :\
+					base)
+
 extern phys_addr_t arm64_dma_phys_limit;
 #define ARCH_LOW_ADDRESS_LIMIT	(arm64_dma_phys_limit - 1)
 
-- 
2.19.2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH V4 4/6] arm64: mm: Offset TTBR1 to allow 52-bit PTRS_PER_PGD

[Steve Capper]

Enabling 52-bit VAs on arm64 requires that the PGD table expands from 64
entries (for the 48-bit case) to 1024 entries. This quantity,
PTRS_PER_PGD is used as follows to compute which PGD entry corresponds
to a given virtual address, addr:

pgd_index(addr) -> (addr >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1)

Userspace addresses are prefixed by 0's, so for a 48-bit userspace
address, uva, the following is true:
(uva >> PGDIR_SHIFT) & (1024 - 1) == (uva >> PGDIR_SHIFT) & (64 - 1)

In other words, a 48-bit userspace address will have the same pgd_index
when using PTRS_PER_PGD = 64 and 1024.

Kernel addresses are prefixed by 1's so, given a 48-bit kernel address,
kva, we have the following inequality:
(kva >> PGDIR_SHIFT) & (1024 - 1) != (kva >> PGDIR_SHIFT) & (64 - 1)

In other words a 48-bit kernel virtual address will have a different
pgd_index when using PTRS_PER_PGD = 64 and 1024.

If, however, we note that:
kva = 0xFFFF << 48 + lower (where lower[63:48] == 0b)
and, PGDIR_SHIFT = 42 (as we are dealing with 64KB PAGE_SIZE)

We can consider:
(kva >> PGDIR_SHIFT) & (1024 - 1) - (kva >> PGDIR_SHIFT) & (64 - 1)
 = (0xFFFF << 6) & 0x3FF - (0xFFFF << 6) & 0x3F	// "lower" cancels out
 = 0x3C0

In other words, one can switch PTRS_PER_PGD to the 52-bit value globally
provided that they increment ttbr1_el1 by 0x3C0 * 8 = 0x1E00 bytes when
running with 48-bit kernel VAs (TCR_EL1.T1SZ = 16).

For kernel configuration where 52-bit userspace VAs are possible, this
patch offsets ttbr1_el1 and sets PTRS_PER_PGD corresponding to the
52-bit value.

Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Steve Capper <steve.capper@arm.com>

---

This patch is new in V4 of the series
---
 arch/arm64/include/asm/asm-uaccess.h   |  4 ++++
 arch/arm64/include/asm/assembler.h     | 23 +++++++++++++++++++++++
 arch/arm64/include/asm/pgtable-hwdef.h |  9 +++++++++
 arch/arm64/include/asm/uaccess.h       |  4 ++++
 arch/arm64/kernel/head.S               |  1 +
 arch/arm64/kernel/hibernate-asm.S      |  1 +
 arch/arm64/mm/proc.S                   |  4 ++++
 7 files changed, 46 insertions(+)

diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h
index 4128bec033f6..cd361dd16b12 100644
--- a/arch/arm64/include/asm/asm-uaccess.h
+++ b/arch/arm64/include/asm/asm-uaccess.h
@@ -14,11 +14,13 @@
 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
 	.macro	__uaccess_ttbr0_disable, tmp1
 	mrs	\tmp1, ttbr1_el1			// swapper_pg_dir
+	restore_ttbr1 \tmp1
 	bic	\tmp1, \tmp1, #TTBR_ASID_MASK
 	sub	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE	// reserved_ttbr0 just before swapper_pg_dir
 	msr	ttbr0_el1, \tmp1			// set reserved TTBR0_EL1
 	isb
 	add	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE
+	offset_ttbr1 \tmp1
 	msr	ttbr1_el1, \tmp1		// set reserved ASID
 	isb
 	.endm
@@ -27,8 +29,10 @@
 	get_thread_info \tmp1
 	ldr	\tmp1, [\tmp1, #TSK_TI_TTBR0]	// load saved TTBR0_EL1
 	mrs	\tmp2, ttbr1_el1
+	restore_ttbr1 \tmp2
 	extr    \tmp2, \tmp2, \tmp1, #48
 	ror     \tmp2, \tmp2, #16
+	offset_ttbr1 \tmp2
 	msr	ttbr1_el1, \tmp2		// set the active ASID
 	isb
 	msr	ttbr0_el1, \tmp1		// set the non-PAN TTBR0_EL1
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 6142402c2eb4..e2fe378d2a63 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -515,6 +515,29 @@ USER(\label, ic	ivau, \tmp2)			// invalidate I line PoU
 	mrs	\rd, sp_el0
 	.endm
 
+/*
+ * Offset ttbr1 to allow for 48-bit kernel VAs set with 52-bit PTRS_PER_PGD.
+ * orr is used as it can cover the immediate value (and is idempotent).
+ * In future this may be nop'ed out when dealing with 52-bit kernel VAs.
+ * 	ttbr: Value of ttbr to set, modified.
+ */
+	.macro	offset_ttbr1, ttbr
+#ifdef CONFIG_ARM64_52BIT_VA
+	orr	\ttbr, \ttbr, #TTBR1_BADDR_4852_OFFSET
+#endif
+	.endm
+
+/*
+ * Perform the reverse of offset_ttbr1.
+ * bic is used as it can cover the immediate value and, in future, won't need
+ * to be nop'ed out when dealing with 52-bit kernel VAs.
+ */
+	.macro	restore_ttbr1, ttbr
+#ifdef CONFIG_ARM64_52BIT_VA
+	bic	\ttbr, \ttbr, #TTBR1_BADDR_4852_OFFSET
+#endif
+	.endm
+
 /*
  * Arrange a physical address in a TTBR register, taking care of 52-bit
  * addresses.
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index 1d7d8da2ef9b..4a29c7e03ae4 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -80,7 +80,11 @@
 #define PGDIR_SHIFT		ARM64_HW_PGTABLE_LEVEL_SHIFT(4 - CONFIG_PGTABLE_LEVELS)
 #define PGDIR_SIZE		(_AC(1, UL) << PGDIR_SHIFT)
 #define PGDIR_MASK		(~(PGDIR_SIZE-1))
+#ifdef CONFIG_ARM64_52BIT_VA
+#define PTRS_PER_PGD		(1 << (52 - PGDIR_SHIFT))
+#else
 #define PTRS_PER_PGD		(1 << (VA_BITS - PGDIR_SHIFT))
+#endif
 
 /*
  * Section address mask and size definitions.
@@ -306,4 +310,9 @@
 #define TTBR_BADDR_MASK_52	(((UL(1) << 46) - 1) << 2)
 #endif
 
+#ifdef CONFIG_ARM64_52BIT_VA
+#define TTBR1_BADDR_4852_OFFSET	(((UL(1) << (52 - PGDIR_SHIFT)) - \
+				 (UL(1) << (48 - PGDIR_SHIFT))) * 8)
+#endif
+
 #endif
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 07c34087bd5e..df60b3978568 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -124,7 +124,11 @@ static inline void __uaccess_ttbr0_disable(void)
 	ttbr = read_sysreg(ttbr1_el1);
 	ttbr &= ~TTBR_ASID_MASK;
 	/* reserved_ttbr0 placed before swapper_pg_dir */
+#ifdef CONFIG_ARM64_52BIT_VA
+	write_sysreg((ttbr & ~TTBR1_BADDR_4852_OFFSET) - RESERVED_TTBR0_SIZE, ttbr0_el1);
+#else
 	write_sysreg(ttbr - RESERVED_TTBR0_SIZE, ttbr0_el1);
+#endif
 	isb();
 	/* Set reserved ASID */
 	write_sysreg(ttbr, ttbr1_el1);
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 4471f570a295..f60081be9a1b 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -769,6 +769,7 @@ ENTRY(__enable_mmu)
 	phys_to_ttbr x1, x1
 	phys_to_ttbr x2, x2
 	msr	ttbr0_el1, x2			// load TTBR0
+	offset_ttbr1 x1
 	msr	ttbr1_el1, x1			// load TTBR1
 	isb
 	msr	sctlr_el1, x0
diff --git a/arch/arm64/kernel/hibernate-asm.S b/arch/arm64/kernel/hibernate-asm.S
index dd14ab8c9f72..fe36d85c60bd 100644
--- a/arch/arm64/kernel/hibernate-asm.S
+++ b/arch/arm64/kernel/hibernate-asm.S
@@ -40,6 +40,7 @@
 	tlbi	vmalle1
 	dsb	nsh
 	phys_to_ttbr \tmp, \page_table
+	offset_ttbr1 \tmp
 	msr	ttbr1_el1, \tmp
 	isb
 .endm
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 2c75b0b903ae..2db1c491d45d 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -182,6 +182,7 @@ ENDPROC(cpu_do_switch_mm)
 .macro	__idmap_cpu_set_reserved_ttbr1, tmp1, tmp2
 	adrp	\tmp1, empty_zero_page
 	phys_to_ttbr \tmp2, \tmp1
+	offset_ttbr1 \tmp2
 	msr	ttbr1_el1, \tmp2
 	isb
 	tlbi	vmalle1
@@ -200,6 +201,7 @@ ENTRY(idmap_cpu_replace_ttbr1)
 
 	__idmap_cpu_set_reserved_ttbr1 x1, x3
 
+	offset_ttbr1 x0
 	msr	ttbr1_el1, x0
 	isb
 
@@ -254,6 +256,7 @@ ENTRY(idmap_kpti_install_ng_mappings)
 	pte		.req	x16
 
 	mrs	swapper_ttb, ttbr1_el1
+	restore_ttbr1	swapper_ttb
 	adr	flag_ptr, __idmap_kpti_flag
 
 	cbnz	cpu, __idmap_kpti_secondary
@@ -373,6 +376,7 @@ __idmap_kpti_secondary:
 	cbnz	w18, 1b
 
 	/* All done, act like nothing happened */
+	offset_ttbr1 swapper_ttb
 	msr	ttbr1_el1, swapper_ttb
 	isb
 	ret
-- 
2.19.2

[PATCH V4 4/6] arm64: mm: Offset TTBR1 to allow 52-bit PTRS_PER_PGD

[Steve Capper]

Enabling 52-bit VAs on arm64 requires that the PGD table expands from 64
entries (for the 48-bit case) to 1024 entries. This quantity,
PTRS_PER_PGD is used as follows to compute which PGD entry corresponds
to a given virtual address, addr:

pgd_index(addr) -> (addr >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1)

Userspace addresses are prefixed by 0's, so for a 48-bit userspace
address, uva, the following is true:
(uva >> PGDIR_SHIFT) & (1024 - 1) == (uva >> PGDIR_SHIFT) & (64 - 1)

In other words, a 48-bit userspace address will have the same pgd_index
when using PTRS_PER_PGD = 64 and 1024.

Kernel addresses are prefixed by 1's so, given a 48-bit kernel address,
kva, we have the following inequality:
(kva >> PGDIR_SHIFT) & (1024 - 1) != (kva >> PGDIR_SHIFT) & (64 - 1)

In other words a 48-bit kernel virtual address will have a different
pgd_index when using PTRS_PER_PGD = 64 and 1024.

If, however, we note that:
kva = 0xFFFF << 48 + lower (where lower[63:48] == 0b)
and, PGDIR_SHIFT = 42 (as we are dealing with 64KB PAGE_SIZE)

We can consider:
(kva >> PGDIR_SHIFT) & (1024 - 1) - (kva >> PGDIR_SHIFT) & (64 - 1)
 = (0xFFFF << 6) & 0x3FF - (0xFFFF << 6) & 0x3F	// "lower" cancels out
 = 0x3C0

In other words, one can switch PTRS_PER_PGD to the 52-bit value globally
provided that they increment ttbr1_el1 by 0x3C0 * 8 = 0x1E00 bytes when
running with 48-bit kernel VAs (TCR_EL1.T1SZ = 16).

For kernel configuration where 52-bit userspace VAs are possible, this
patch offsets ttbr1_el1 and sets PTRS_PER_PGD corresponding to the
52-bit value.

Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Steve Capper <steve.capper@arm.com>

---

This patch is new in V4 of the series
---
 arch/arm64/include/asm/asm-uaccess.h   |  4 ++++
 arch/arm64/include/asm/assembler.h     | 23 +++++++++++++++++++++++
 arch/arm64/include/asm/pgtable-hwdef.h |  9 +++++++++
 arch/arm64/include/asm/uaccess.h       |  4 ++++
 arch/arm64/kernel/head.S               |  1 +
 arch/arm64/kernel/hibernate-asm.S      |  1 +
 arch/arm64/mm/proc.S                   |  4 ++++
 7 files changed, 46 insertions(+)

diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h
index 4128bec033f6..cd361dd16b12 100644
--- a/arch/arm64/include/asm/asm-uaccess.h
+++ b/arch/arm64/include/asm/asm-uaccess.h
@@ -14,11 +14,13 @@
 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
 	.macro	__uaccess_ttbr0_disable, tmp1
 	mrs	\tmp1, ttbr1_el1			// swapper_pg_dir
+	restore_ttbr1 \tmp1
 	bic	\tmp1, \tmp1, #TTBR_ASID_MASK
 	sub	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE	// reserved_ttbr0 just before swapper_pg_dir
 	msr	ttbr0_el1, \tmp1			// set reserved TTBR0_EL1
 	isb
 	add	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE
+	offset_ttbr1 \tmp1
 	msr	ttbr1_el1, \tmp1		// set reserved ASID
 	isb
 	.endm
@@ -27,8 +29,10 @@
 	get_thread_info \tmp1
 	ldr	\tmp1, [\tmp1, #TSK_TI_TTBR0]	// load saved TTBR0_EL1
 	mrs	\tmp2, ttbr1_el1
+	restore_ttbr1 \tmp2
 	extr    \tmp2, \tmp2, \tmp1, #48
 	ror     \tmp2, \tmp2, #16
+	offset_ttbr1 \tmp2
 	msr	ttbr1_el1, \tmp2		// set the active ASID
 	isb
 	msr	ttbr0_el1, \tmp1		// set the non-PAN TTBR0_EL1
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 6142402c2eb4..e2fe378d2a63 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -515,6 +515,29 @@ USER(\label, ic	ivau, \tmp2)			// invalidate I line PoU
 	mrs	\rd, sp_el0
 	.endm
 
+/*
+ * Offset ttbr1 to allow for 48-bit kernel VAs set with 52-bit PTRS_PER_PGD.
+ * orr is used as it can cover the immediate value (and is idempotent).
+ * In future this may be nop'ed out when dealing with 52-bit kernel VAs.
+ * 	ttbr: Value of ttbr to set, modified.
+ */
+	.macro	offset_ttbr1, ttbr
+#ifdef CONFIG_ARM64_52BIT_VA
+	orr	\ttbr, \ttbr, #TTBR1_BADDR_4852_OFFSET
+#endif
+	.endm
+
+/*
+ * Perform the reverse of offset_ttbr1.
+ * bic is used as it can cover the immediate value and, in future, won't need
+ * to be nop'ed out when dealing with 52-bit kernel VAs.
+ */
+	.macro	restore_ttbr1, ttbr
+#ifdef CONFIG_ARM64_52BIT_VA
+	bic	\ttbr, \ttbr, #TTBR1_BADDR_4852_OFFSET
+#endif
+	.endm
+
 /*
  * Arrange a physical address in a TTBR register, taking care of 52-bit
  * addresses.
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index 1d7d8da2ef9b..4a29c7e03ae4 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -80,7 +80,11 @@
 #define PGDIR_SHIFT		ARM64_HW_PGTABLE_LEVEL_SHIFT(4 - CONFIG_PGTABLE_LEVELS)
 #define PGDIR_SIZE		(_AC(1, UL) << PGDIR_SHIFT)
 #define PGDIR_MASK		(~(PGDIR_SIZE-1))
+#ifdef CONFIG_ARM64_52BIT_VA
+#define PTRS_PER_PGD		(1 << (52 - PGDIR_SHIFT))
+#else
 #define PTRS_PER_PGD		(1 << (VA_BITS - PGDIR_SHIFT))
+#endif
 
 /*
  * Section address mask and size definitions.
@@ -306,4 +310,9 @@
 #define TTBR_BADDR_MASK_52	(((UL(1) << 46) - 1) << 2)
 #endif
 
+#ifdef CONFIG_ARM64_52BIT_VA
+#define TTBR1_BADDR_4852_OFFSET	(((UL(1) << (52 - PGDIR_SHIFT)) - \
+				 (UL(1) << (48 - PGDIR_SHIFT))) * 8)
+#endif
+
 #endif
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 07c34087bd5e..df60b3978568 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -124,7 +124,11 @@ static inline void __uaccess_ttbr0_disable(void)
 	ttbr = read_sysreg(ttbr1_el1);
 	ttbr &= ~TTBR_ASID_MASK;
 	/* reserved_ttbr0 placed before swapper_pg_dir */
+#ifdef CONFIG_ARM64_52BIT_VA
+	write_sysreg((ttbr & ~TTBR1_BADDR_4852_OFFSET) - RESERVED_TTBR0_SIZE, ttbr0_el1);
+#else
 	write_sysreg(ttbr - RESERVED_TTBR0_SIZE, ttbr0_el1);
+#endif
 	isb();
 	/* Set reserved ASID */
 	write_sysreg(ttbr, ttbr1_el1);
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 4471f570a295..f60081be9a1b 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -769,6 +769,7 @@ ENTRY(__enable_mmu)
 	phys_to_ttbr x1, x1
 	phys_to_ttbr x2, x2
 	msr	ttbr0_el1, x2			// load TTBR0
+	offset_ttbr1 x1
 	msr	ttbr1_el1, x1			// load TTBR1
 	isb
 	msr	sctlr_el1, x0
diff --git a/arch/arm64/kernel/hibernate-asm.S b/arch/arm64/kernel/hibernate-asm.S
index dd14ab8c9f72..fe36d85c60bd 100644
--- a/arch/arm64/kernel/hibernate-asm.S
+++ b/arch/arm64/kernel/hibernate-asm.S
@@ -40,6 +40,7 @@
 	tlbi	vmalle1
 	dsb	nsh
 	phys_to_ttbr \tmp, \page_table
+	offset_ttbr1 \tmp
 	msr	ttbr1_el1, \tmp
 	isb
 .endm
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 2c75b0b903ae..2db1c491d45d 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -182,6 +182,7 @@ ENDPROC(cpu_do_switch_mm)
 .macro	__idmap_cpu_set_reserved_ttbr1, tmp1, tmp2
 	adrp	\tmp1, empty_zero_page
 	phys_to_ttbr \tmp2, \tmp1
+	offset_ttbr1 \tmp2
 	msr	ttbr1_el1, \tmp2
 	isb
 	tlbi	vmalle1
@@ -200,6 +201,7 @@ ENTRY(idmap_cpu_replace_ttbr1)
 
 	__idmap_cpu_set_reserved_ttbr1 x1, x3
 
+	offset_ttbr1 x0
 	msr	ttbr1_el1, x0
 	isb
 
@@ -254,6 +256,7 @@ ENTRY(idmap_kpti_install_ng_mappings)
 	pte		.req	x16
 
 	mrs	swapper_ttb, ttbr1_el1
+	restore_ttbr1	swapper_ttb
 	adr	flag_ptr, __idmap_kpti_flag
 
 	cbnz	cpu, __idmap_kpti_secondary
@@ -373,6 +376,7 @@ __idmap_kpti_secondary:
 	cbnz	w18, 1b
 
 	/* All done, act like nothing happened */
+	offset_ttbr1 swapper_ttb
 	msr	ttbr1_el1, swapper_ttb
 	isb
 	ret
-- 
2.19.2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH V4 4/6] arm64: mm: Offset TTBR1 to allow 52-bit PTRS_PER_PGD

[Catalin Marinas]

On Wed, Dec 05, 2018 at 04:41:43PM +0000, Steve Capper wrote:
> diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h
> index 4128bec033f6..cd361dd16b12 100644
> --- a/arch/arm64/include/asm/asm-uaccess.h
> +++ b/arch/arm64/include/asm/asm-uaccess.h
> @@ -14,11 +14,13 @@
>  #ifdef CONFIG_ARM64_SW_TTBR0_PAN
>  	.macro	__uaccess_ttbr0_disable, tmp1
>  	mrs	\tmp1, ttbr1_el1			// swapper_pg_dir
> +	restore_ttbr1 \tmp1
>  	bic	\tmp1, \tmp1, #TTBR_ASID_MASK
>  	sub	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE	// reserved_ttbr0 just before swapper_pg_dir
>  	msr	ttbr0_el1, \tmp1			// set reserved TTBR0_EL1
>  	isb
>  	add	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE
> +	offset_ttbr1 \tmp1
>  	msr	ttbr1_el1, \tmp1		// set reserved ASID
>  	isb
>  	.endm
> @@ -27,8 +29,10 @@
>  	get_thread_info \tmp1
>  	ldr	\tmp1, [\tmp1, #TSK_TI_TTBR0]	// load saved TTBR0_EL1
>  	mrs	\tmp2, ttbr1_el1
> +	restore_ttbr1 \tmp2
>  	extr    \tmp2, \tmp2, \tmp1, #48
>  	ror     \tmp2, \tmp2, #16
> +	offset_ttbr1 \tmp2
>  	msr	ttbr1_el1, \tmp2		// set the active ASID
>  	isb
>  	msr	ttbr0_el1, \tmp1		// set the non-PAN TTBR0_EL1

The patch looks alright but I think we can simplify it further if we add:

	depends on ARM64_PAN || !ARM64_SW_TTBR0_PAN

to the 52-bit Kconfig entry.

-- 
Catalin

Re: [PATCH V4 4/6] arm64: mm: Offset TTBR1 to allow 52-bit PTRS_PER_PGD

[Catalin Marinas]

On Wed, Dec 05, 2018 at 04:41:43PM +0000, Steve Capper wrote:
> diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h
> index 4128bec033f6..cd361dd16b12 100644
> --- a/arch/arm64/include/asm/asm-uaccess.h
> +++ b/arch/arm64/include/asm/asm-uaccess.h
> @@ -14,11 +14,13 @@
>  #ifdef CONFIG_ARM64_SW_TTBR0_PAN
>  	.macro	__uaccess_ttbr0_disable, tmp1
>  	mrs	\tmp1, ttbr1_el1			// swapper_pg_dir
> +	restore_ttbr1 \tmp1
>  	bic	\tmp1, \tmp1, #TTBR_ASID_MASK
>  	sub	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE	// reserved_ttbr0 just before swapper_pg_dir
>  	msr	ttbr0_el1, \tmp1			// set reserved TTBR0_EL1
>  	isb
>  	add	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE
> +	offset_ttbr1 \tmp1
>  	msr	ttbr1_el1, \tmp1		// set reserved ASID
>  	isb
>  	.endm
> @@ -27,8 +29,10 @@
>  	get_thread_info \tmp1
>  	ldr	\tmp1, [\tmp1, #TSK_TI_TTBR0]	// load saved TTBR0_EL1
>  	mrs	\tmp2, ttbr1_el1
> +	restore_ttbr1 \tmp2
>  	extr    \tmp2, \tmp2, \tmp1, #48
>  	ror     \tmp2, \tmp2, #16
> +	offset_ttbr1 \tmp2
>  	msr	ttbr1_el1, \tmp2		// set the active ASID
>  	isb
>  	msr	ttbr0_el1, \tmp1		// set the non-PAN TTBR0_EL1

The patch looks alright but I think we can simplify it further if we add:

	depends on ARM64_PAN || !ARM64_SW_TTBR0_PAN

to the 52-bit Kconfig entry.

-- 
Catalin

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH V4 4/6] arm64: mm: Offset TTBR1 to allow 52-bit PTRS_PER_PGD

[Steve Capper]

On Thu, Dec 06, 2018 at 11:50:12AM +0000, Catalin Marinas wrote:
> On Wed, Dec 05, 2018 at 04:41:43PM +0000, Steve Capper wrote:
> > diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h
> > index 4128bec033f6..cd361dd16b12 100644
> > --- a/arch/arm64/include/asm/asm-uaccess.h
> > +++ b/arch/arm64/include/asm/asm-uaccess.h
> > @@ -14,11 +14,13 @@
> >  #ifdef CONFIG_ARM64_SW_TTBR0_PAN
> >  	.macro	__uaccess_ttbr0_disable, tmp1
> >  	mrs	\tmp1, ttbr1_el1			// swapper_pg_dir
> > +	restore_ttbr1 \tmp1
> >  	bic	\tmp1, \tmp1, #TTBR_ASID_MASK
> >  	sub	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE	// reserved_ttbr0 just before swapper_pg_dir
> >  	msr	ttbr0_el1, \tmp1			// set reserved TTBR0_EL1
> >  	isb
> >  	add	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE
> > +	offset_ttbr1 \tmp1
> >  	msr	ttbr1_el1, \tmp1		// set reserved ASID
> >  	isb
> >  	.endm
> > @@ -27,8 +29,10 @@
> >  	get_thread_info \tmp1
> >  	ldr	\tmp1, [\tmp1, #TSK_TI_TTBR0]	// load saved TTBR0_EL1
> >  	mrs	\tmp2, ttbr1_el1
> > +	restore_ttbr1 \tmp2
> >  	extr    \tmp2, \tmp2, \tmp1, #48
> >  	ror     \tmp2, \tmp2, #16
> > +	offset_ttbr1 \tmp2
> >  	msr	ttbr1_el1, \tmp2		// set the active ASID
> >  	isb
> >  	msr	ttbr0_el1, \tmp1		// set the non-PAN TTBR0_EL1
> 
> The patch looks alright but I think we can simplify it further if we add:
> 
> 	depends on ARM64_PAN || !ARM64_SW_TTBR0_PAN
> 
> to the 52-bit Kconfig entry.

Ahh, thank you okay, I didn't make the connection that Privileged access
never was a mandatory feature in ARMv8.1.

Cheers,
-- 
Steve

Re: [PATCH V4 4/6] arm64: mm: Offset TTBR1 to allow 52-bit PTRS_PER_PGD

[Steve Capper]

On Thu, Dec 06, 2018 at 11:50:12AM +0000, Catalin Marinas wrote:
> On Wed, Dec 05, 2018 at 04:41:43PM +0000, Steve Capper wrote:
> > diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h
> > index 4128bec033f6..cd361dd16b12 100644
> > --- a/arch/arm64/include/asm/asm-uaccess.h
> > +++ b/arch/arm64/include/asm/asm-uaccess.h
> > @@ -14,11 +14,13 @@
> >  #ifdef CONFIG_ARM64_SW_TTBR0_PAN
> >  	.macro	__uaccess_ttbr0_disable, tmp1
> >  	mrs	\tmp1, ttbr1_el1			// swapper_pg_dir
> > +	restore_ttbr1 \tmp1
> >  	bic	\tmp1, \tmp1, #TTBR_ASID_MASK
> >  	sub	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE	// reserved_ttbr0 just before swapper_pg_dir
> >  	msr	ttbr0_el1, \tmp1			// set reserved TTBR0_EL1
> >  	isb
> >  	add	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE
> > +	offset_ttbr1 \tmp1
> >  	msr	ttbr1_el1, \tmp1		// set reserved ASID
> >  	isb
> >  	.endm
> > @@ -27,8 +29,10 @@
> >  	get_thread_info \tmp1
> >  	ldr	\tmp1, [\tmp1, #TSK_TI_TTBR0]	// load saved TTBR0_EL1
> >  	mrs	\tmp2, ttbr1_el1
> > +	restore_ttbr1 \tmp2
> >  	extr    \tmp2, \tmp2, \tmp1, #48
> >  	ror     \tmp2, \tmp2, #16
> > +	offset_ttbr1 \tmp2
> >  	msr	ttbr1_el1, \tmp2		// set the active ASID
> >  	isb
> >  	msr	ttbr0_el1, \tmp1		// set the non-PAN TTBR0_EL1
> 
> The patch looks alright but I think we can simplify it further if we add:
> 
> 	depends on ARM64_PAN || !ARM64_SW_TTBR0_PAN
> 
> to the 52-bit Kconfig entry.

Ahh, thank you okay, I didn't make the connection that Privileged access
never was a mandatory feature in ARMv8.1.

Cheers,
-- 
Steve

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH V4 5/6] arm64: mm: introduce 52-bit userspace support

[Steve Capper]

On arm64 there is optional support for a 52-bit virtual address space.
To exploit this one has to be running with a 64KB page size and be
running on hardware that supports this.

For an arm64 kernel supporting a 48 bit VA with a 64KB page size,
some changes are needed to support a 52-bit userspace:
 * TCR_EL1.T0SZ needs to be 12 instead of 16,
 * TASK_SIZE needs to reflect the new size.

This patch implements the above when the support for 52-bit VAs is
detected at early boot time.

On arm64 userspace addresses translation is controlled by TTBR0_EL1. As
well as userspace, TTBR0_EL1 controls:
 * The identity mapping,
 * EFI runtime code.

It is possible to run a kernel with an identity mapping that has a
larger VA size than userspace (and for this case __cpu_set_tcr_t0sz()
would set TCR_EL1.T0SZ as appropriate). However, when the conditions for
52-bit userspace are met; it is possible to keep TCR_EL1.T0SZ fixed at
12. Thus in this patch, the TCR_EL1.T0SZ size changing logic is
disabled.

Signed-off-by: Steve Capper <steve.capper@arm.com>

---

Changed in V4, pgd_index logic removed as we offset ttbr1 instead
---
 arch/arm64/Kconfig                   |  4 ++++
 arch/arm64/include/asm/assembler.h   |  7 +++----
 arch/arm64/include/asm/mmu_context.h |  3 +++
 arch/arm64/include/asm/processor.h   | 14 +++++++++-----
 arch/arm64/kernel/head.S             | 13 +++++++++++++
 arch/arm64/mm/fault.c                |  2 +-
 arch/arm64/mm/mmu.c                  |  1 +
 arch/arm64/mm/proc.S                 | 10 +++++++++-
 8 files changed, 43 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 787d7850e064..eab02d24f5d1 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -709,6 +709,10 @@ config ARM64_PA_BITS_52
 
 endchoice
 
+config ARM64_52BIT_VA
+	def_bool y
+	depends on ARM64_VA_BITS_48 && ARM64_64K_PAGES
+
 config ARM64_PA_BITS
 	int
 	default 48 if ARM64_PA_BITS_48
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index e2fe378d2a63..243ec4f0c00f 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -342,11 +342,10 @@ alternative_endif
 	.endm
 
 /*
- * tcr_set_idmap_t0sz - update TCR.T0SZ so that we can load the ID map
+ * tcr_set_t0sz - update TCR.T0SZ so that we can load the ID map
  */
-	.macro	tcr_set_idmap_t0sz, valreg, tmpreg
-	ldr_l	\tmpreg, idmap_t0sz
-	bfi	\valreg, \tmpreg, #TCR_T0SZ_OFFSET, #TCR_TxSZ_WIDTH
+	.macro	tcr_set_t0sz, valreg, t0sz
+	bfi	\valreg, \t0sz, #TCR_T0SZ_OFFSET, #TCR_TxSZ_WIDTH
 	.endm
 
 /*
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index 1e58bf58c22b..b125fafc611b 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -72,6 +72,9 @@ extern u64 idmap_ptrs_per_pgd;
 
 static inline bool __cpu_uses_extended_idmap(void)
 {
+	if (IS_ENABLED(CONFIG_ARM64_52BIT_VA))
+		return false;
+
 	return unlikely(idmap_t0sz != TCR_T0SZ(VA_BITS));
 }
 
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index fe95fd8b065e..b363fc705be4 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -19,11 +19,12 @@
 #ifndef __ASM_PROCESSOR_H
 #define __ASM_PROCESSOR_H
 
-#define TASK_SIZE_64		(UL(1) << VA_BITS)
-
-#define KERNEL_DS	UL(-1)
-#define USER_DS		(TASK_SIZE_64 - 1)
-
+#define KERNEL_DS		UL(-1)
+#ifdef CONFIG_ARM64_52BIT_VA
+#define USER_DS			((UL(1) << 52) - 1)
+#else
+#define USER_DS			((UL(1) << VA_BITS) - 1)
+#endif /* CONFIG_ARM64_52IT_VA */
 #ifndef __ASSEMBLY__
 #ifdef __KERNEL__
 
@@ -48,6 +49,9 @@
 
 #define DEFAULT_MAP_WINDOW_64	(UL(1) << VA_BITS)
 
+extern u64 vabits_user;
+#define TASK_SIZE_64		(UL(1) << vabits_user)
+
 #ifdef CONFIG_COMPAT
 #define TASK_SIZE_32		UL(0x100000000)
 #define TASK_SIZE		(test_thread_flag(TIF_32BIT) ? \
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index f60081be9a1b..5bc776b8ee5e 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -318,6 +318,19 @@ __create_page_tables:
 	adrp	x0, idmap_pg_dir
 	adrp	x3, __idmap_text_start		// __pa(__idmap_text_start)
 
+#ifdef CONFIG_ARM64_52BIT_VA
+	mrs_s	x6, SYS_ID_AA64MMFR2_EL1
+	and	x6, x6, #(0xf << ID_AA64MMFR2_LVA_SHIFT)
+	mov	x5, #52
+	cbnz	x6, 1f
+#endif
+	mov	x5, #VA_BITS
+1:
+	adr_l	x6, vabits_user
+	str	x5, [x6]
+	dmb	sy
+	dc	ivac, x6		// Invalidate potentially stale cache line
+
 	/*
 	 * VA_BITS may be too small to allow for an ID mapping to be created
 	 * that covers system RAM if that is located sufficiently high in the
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 7d9571f4ae3d..5fe6d2e40e9b 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -160,7 +160,7 @@ void show_pte(unsigned long addr)
 
 	pr_alert("%s pgtable: %luk pages, %u-bit VAs, pgdp = %p\n",
 		 mm == &init_mm ? "swapper" : "user", PAGE_SIZE / SZ_1K,
-		 VA_BITS, mm->pgd);
+		 mm == &init_mm ? VA_BITS : (int) vabits_user, mm->pgd);
 	pgdp = pgd_offset(mm, addr);
 	pgd = READ_ONCE(*pgdp);
 	pr_alert("[%016lx] pgd=%016llx", addr, pgd_val(pgd));
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 394b8d554def..f8fc393143ea 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -52,6 +52,7 @@
 
 u64 idmap_t0sz = TCR_T0SZ(VA_BITS);
 u64 idmap_ptrs_per_pgd = PTRS_PER_PGD;
+u64 vabits_user __ro_after_init;
 
 u64 kimage_voffset __ro_after_init;
 EXPORT_SYMBOL(kimage_voffset);
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 2db1c491d45d..0cf86b17714c 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -450,7 +450,15 @@ ENTRY(__cpu_setup)
 	ldr	x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
 			TCR_TG_FLAGS | TCR_KASLR_FLAGS | TCR_ASID16 | \
 			TCR_TBI0 | TCR_A1
-	tcr_set_idmap_t0sz	x10, x9
+
+#ifdef CONFIG_ARM64_52BIT_VA
+	ldr_l 		x9, vabits_user
+	sub		x9, xzr, x9
+	add		x9, x9, #64
+#else
+	ldr_l		x9, idmap_t0sz
+#endif
+	tcr_set_t0sz	x10, x9
 
 	/*
 	 * Set the IPS bits in TCR_EL1.
-- 
2.19.2

[PATCH V4 5/6] arm64: mm: introduce 52-bit userspace support

[Steve Capper]

On arm64 there is optional support for a 52-bit virtual address space.
To exploit this one has to be running with a 64KB page size and be
running on hardware that supports this.

For an arm64 kernel supporting a 48 bit VA with a 64KB page size,
some changes are needed to support a 52-bit userspace:
 * TCR_EL1.T0SZ needs to be 12 instead of 16,
 * TASK_SIZE needs to reflect the new size.

This patch implements the above when the support for 52-bit VAs is
detected at early boot time.

On arm64 userspace addresses translation is controlled by TTBR0_EL1. As
well as userspace, TTBR0_EL1 controls:
 * The identity mapping,
 * EFI runtime code.

It is possible to run a kernel with an identity mapping that has a
larger VA size than userspace (and for this case __cpu_set_tcr_t0sz()
would set TCR_EL1.T0SZ as appropriate). However, when the conditions for
52-bit userspace are met; it is possible to keep TCR_EL1.T0SZ fixed at
12. Thus in this patch, the TCR_EL1.T0SZ size changing logic is
disabled.

Signed-off-by: Steve Capper <steve.capper@arm.com>

---

Changed in V4, pgd_index logic removed as we offset ttbr1 instead
---
 arch/arm64/Kconfig                   |  4 ++++
 arch/arm64/include/asm/assembler.h   |  7 +++----
 arch/arm64/include/asm/mmu_context.h |  3 +++
 arch/arm64/include/asm/processor.h   | 14 +++++++++-----
 arch/arm64/kernel/head.S             | 13 +++++++++++++
 arch/arm64/mm/fault.c                |  2 +-
 arch/arm64/mm/mmu.c                  |  1 +
 arch/arm64/mm/proc.S                 | 10 +++++++++-
 8 files changed, 43 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 787d7850e064..eab02d24f5d1 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -709,6 +709,10 @@ config ARM64_PA_BITS_52
 
 endchoice
 
+config ARM64_52BIT_VA
+	def_bool y
+	depends on ARM64_VA_BITS_48 && ARM64_64K_PAGES
+
 config ARM64_PA_BITS
 	int
 	default 48 if ARM64_PA_BITS_48
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index e2fe378d2a63..243ec4f0c00f 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -342,11 +342,10 @@ alternative_endif
 	.endm
 
 /*
- * tcr_set_idmap_t0sz - update TCR.T0SZ so that we can load the ID map
+ * tcr_set_t0sz - update TCR.T0SZ so that we can load the ID map
  */
-	.macro	tcr_set_idmap_t0sz, valreg, tmpreg
-	ldr_l	\tmpreg, idmap_t0sz
-	bfi	\valreg, \tmpreg, #TCR_T0SZ_OFFSET, #TCR_TxSZ_WIDTH
+	.macro	tcr_set_t0sz, valreg, t0sz
+	bfi	\valreg, \t0sz, #TCR_T0SZ_OFFSET, #TCR_TxSZ_WIDTH
 	.endm
 
 /*
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index 1e58bf58c22b..b125fafc611b 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -72,6 +72,9 @@ extern u64 idmap_ptrs_per_pgd;
 
 static inline bool __cpu_uses_extended_idmap(void)
 {
+	if (IS_ENABLED(CONFIG_ARM64_52BIT_VA))
+		return false;
+
 	return unlikely(idmap_t0sz != TCR_T0SZ(VA_BITS));
 }
 
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index fe95fd8b065e..b363fc705be4 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -19,11 +19,12 @@
 #ifndef __ASM_PROCESSOR_H
 #define __ASM_PROCESSOR_H
 
-#define TASK_SIZE_64		(UL(1) << VA_BITS)
-
-#define KERNEL_DS	UL(-1)
-#define USER_DS		(TASK_SIZE_64 - 1)
-
+#define KERNEL_DS		UL(-1)
+#ifdef CONFIG_ARM64_52BIT_VA
+#define USER_DS			((UL(1) << 52) - 1)
+#else
+#define USER_DS			((UL(1) << VA_BITS) - 1)
+#endif /* CONFIG_ARM64_52IT_VA */
 #ifndef __ASSEMBLY__
 #ifdef __KERNEL__
 
@@ -48,6 +49,9 @@
 
 #define DEFAULT_MAP_WINDOW_64	(UL(1) << VA_BITS)
 
+extern u64 vabits_user;
+#define TASK_SIZE_64		(UL(1) << vabits_user)
+
 #ifdef CONFIG_COMPAT
 #define TASK_SIZE_32		UL(0x100000000)
 #define TASK_SIZE		(test_thread_flag(TIF_32BIT) ? \
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index f60081be9a1b..5bc776b8ee5e 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -318,6 +318,19 @@ __create_page_tables:
 	adrp	x0, idmap_pg_dir
 	adrp	x3, __idmap_text_start		// __pa(__idmap_text_start)
 
+#ifdef CONFIG_ARM64_52BIT_VA
+	mrs_s	x6, SYS_ID_AA64MMFR2_EL1
+	and	x6, x6, #(0xf << ID_AA64MMFR2_LVA_SHIFT)
+	mov	x5, #52
+	cbnz	x6, 1f
+#endif
+	mov	x5, #VA_BITS
+1:
+	adr_l	x6, vabits_user
+	str	x5, [x6]
+	dmb	sy
+	dc	ivac, x6		// Invalidate potentially stale cache line
+
 	/*
 	 * VA_BITS may be too small to allow for an ID mapping to be created
 	 * that covers system RAM if that is located sufficiently high in the
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 7d9571f4ae3d..5fe6d2e40e9b 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -160,7 +160,7 @@ void show_pte(unsigned long addr)
 
 	pr_alert("%s pgtable: %luk pages, %u-bit VAs, pgdp = %p\n",
 		 mm == &init_mm ? "swapper" : "user", PAGE_SIZE / SZ_1K,
-		 VA_BITS, mm->pgd);
+		 mm == &init_mm ? VA_BITS : (int) vabits_user, mm->pgd);
 	pgdp = pgd_offset(mm, addr);
 	pgd = READ_ONCE(*pgdp);
 	pr_alert("[%016lx] pgd=%016llx", addr, pgd_val(pgd));
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 394b8d554def..f8fc393143ea 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -52,6 +52,7 @@
 
 u64 idmap_t0sz = TCR_T0SZ(VA_BITS);
 u64 idmap_ptrs_per_pgd = PTRS_PER_PGD;
+u64 vabits_user __ro_after_init;
 
 u64 kimage_voffset __ro_after_init;
 EXPORT_SYMBOL(kimage_voffset);
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 2db1c491d45d..0cf86b17714c 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -450,7 +450,15 @@ ENTRY(__cpu_setup)
 	ldr	x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
 			TCR_TG_FLAGS | TCR_KASLR_FLAGS | TCR_ASID16 | \
 			TCR_TBI0 | TCR_A1
-	tcr_set_idmap_t0sz	x10, x9
+
+#ifdef CONFIG_ARM64_52BIT_VA
+	ldr_l 		x9, vabits_user
+	sub		x9, xzr, x9
+	add		x9, x9, #64
+#else
+	ldr_l		x9, idmap_t0sz
+#endif
+	tcr_set_t0sz	x10, x9
 
 	/*
 	 * Set the IPS bits in TCR_EL1.
-- 
2.19.2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH V4 5/6] arm64: mm: introduce 52-bit userspace support

[Suzuki K Poulose]

Hi Steve,

On 05/12/2018 16:41, Steve Capper wrote:
> On arm64 there is optional support for a 52-bit virtual address space.
> To exploit this one has to be running with a 64KB page size and be
> running on hardware that supports this.
> 
> For an arm64 kernel supporting a 48 bit VA with a 64KB page size,
> some changes are needed to support a 52-bit userspace:
>   * TCR_EL1.T0SZ needs to be 12 instead of 16,
>   * TASK_SIZE needs to reflect the new size.
> 
> This patch implements the above when the support for 52-bit VAs is
> detected at early boot time.
> 
> On arm64 userspace addresses translation is controlled by TTBR0_EL1. As
> well as userspace, TTBR0_EL1 controls:
>   * The identity mapping,
>   * EFI runtime code.
> 
> It is possible to run a kernel with an identity mapping that has a
> larger VA size than userspace (and for this case __cpu_set_tcr_t0sz()
> would set TCR_EL1.T0SZ as appropriate). However, when the conditions for
> 52-bit userspace are met; it is possible to keep TCR_EL1.T0SZ fixed at
> 12. Thus in this patch, the TCR_EL1.T0SZ size changing logic is
> disabled.
> 
> Signed-off-by: Steve Capper <steve.capper@arm.com>
> 
> ---
> 
> Changed in V4, pgd_index logic removed as we offset ttbr1 instead
> ---
>   arch/arm64/Kconfig                   |  4 ++++
>   arch/arm64/include/asm/assembler.h   |  7 +++----
>   arch/arm64/include/asm/mmu_context.h |  3 +++
>   arch/arm64/include/asm/processor.h   | 14 +++++++++-----
>   arch/arm64/kernel/head.S             | 13 +++++++++++++
>   arch/arm64/mm/fault.c                |  2 +-
>   arch/arm64/mm/mmu.c                  |  1 +
>   arch/arm64/mm/proc.S                 | 10 +++++++++-
>   8 files changed, 43 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 787d7850e064..eab02d24f5d1 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -709,6 +709,10 @@ config ARM64_PA_BITS_52
>   
>   endchoice
>   
> +config ARM64_52BIT_VA
> +	def_bool y
> +	depends on ARM64_VA_BITS_48 && ARM64_64K_PAGES
> +
>   config ARM64_PA_BITS
>   	int
>   	default 48 if ARM64_PA_BITS_48
> diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
> index e2fe378d2a63..243ec4f0c00f 100644
> --- a/arch/arm64/include/asm/assembler.h
> +++ b/arch/arm64/include/asm/assembler.h
> @@ -342,11 +342,10 @@ alternative_endif
>   	.endm
>   
>   /*
> - * tcr_set_idmap_t0sz - update TCR.T0SZ so that we can load the ID map
> + * tcr_set_t0sz - update TCR.T0SZ so that we can load the ID map
>    */
> -	.macro	tcr_set_idmap_t0sz, valreg, tmpreg
> -	ldr_l	\tmpreg, idmap_t0sz
> -	bfi	\valreg, \tmpreg, #TCR_T0SZ_OFFSET, #TCR_TxSZ_WIDTH
> +	.macro	tcr_set_t0sz, valreg, t0sz
> +	bfi	\valreg, \t0sz, #TCR_T0SZ_OFFSET, #TCR_TxSZ_WIDTH
>   	.endm
>   
>   /*
> diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
> index 1e58bf58c22b..b125fafc611b 100644
> --- a/arch/arm64/include/asm/mmu_context.h
> +++ b/arch/arm64/include/asm/mmu_context.h
> @@ -72,6 +72,9 @@ extern u64 idmap_ptrs_per_pgd;
>   
>   static inline bool __cpu_uses_extended_idmap(void)
>   {
> +	if (IS_ENABLED(CONFIG_ARM64_52BIT_VA))
> +		return false;
> +
>   	return unlikely(idmap_t0sz != TCR_T0SZ(VA_BITS));
>   }
>   
> diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
> index fe95fd8b065e..b363fc705be4 100644
> --- a/arch/arm64/include/asm/processor.h
> +++ b/arch/arm64/include/asm/processor.h
> @@ -19,11 +19,12 @@
>   #ifndef __ASM_PROCESSOR_H
>   #define __ASM_PROCESSOR_H
>   
> -#define TASK_SIZE_64		(UL(1) << VA_BITS)
> -
> -#define KERNEL_DS	UL(-1)
> -#define USER_DS		(TASK_SIZE_64 - 1)
> -
> +#define KERNEL_DS		UL(-1)
> +#ifdef CONFIG_ARM64_52BIT_VA
> +#define USER_DS			((UL(1) << 52) - 1)
> +#else
> +#define USER_DS			((UL(1) << VA_BITS) - 1)
> +#endif /* CONFIG_ARM64_52IT_VA */
>   #ifndef __ASSEMBLY__
>   #ifdef __KERNEL__
>   
> @@ -48,6 +49,9 @@
>   
>   #define DEFAULT_MAP_WINDOW_64	(UL(1) << VA_BITS)
>   
> +extern u64 vabits_user;
> +#define TASK_SIZE_64		(UL(1) << vabits_user)
> +
>   #ifdef CONFIG_COMPAT
>   #define TASK_SIZE_32		UL(0x100000000)
>   #define TASK_SIZE		(test_thread_flag(TIF_32BIT) ? \
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index f60081be9a1b..5bc776b8ee5e 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -318,6 +318,19 @@ __create_page_tables:
>   	adrp	x0, idmap_pg_dir
>   	adrp	x3, __idmap_text_start		// __pa(__idmap_text_start)
>   
> +#ifdef CONFIG_ARM64_52BIT_VA
> +	mrs_s	x6, SYS_ID_AA64MMFR2_EL1
> +	and	x6, x6, #(0xf << ID_AA64MMFR2_LVA_SHIFT)
> +	mov	x5, #52
> +	cbnz	x6, 1f
> +#endif
> +	mov	x5, #VA_BITS
> +1:
> +	adr_l	x6, vabits_user
> +	str	x5, [x6]
> +	dmb	sy
> +	dc	ivac, x6		// Invalidate potentially stale cache line
> +

I think we may need a check for the secondary CPUs to make sure that they have
the 52bit support once the boot CPU has decided to use the feature and fail the
CPU bring up (just like we do for the granule support).

Suzuki

Re: [PATCH V4 5/6] arm64: mm: introduce 52-bit userspace support

[Suzuki K Poulose]

Hi Steve,

On 05/12/2018 16:41, Steve Capper wrote:
> On arm64 there is optional support for a 52-bit virtual address space.
> To exploit this one has to be running with a 64KB page size and be
> running on hardware that supports this.
> 
> For an arm64 kernel supporting a 48 bit VA with a 64KB page size,
> some changes are needed to support a 52-bit userspace:
>   * TCR_EL1.T0SZ needs to be 12 instead of 16,
>   * TASK_SIZE needs to reflect the new size.
> 
> This patch implements the above when the support for 52-bit VAs is
> detected at early boot time.
> 
> On arm64 userspace addresses translation is controlled by TTBR0_EL1. As
> well as userspace, TTBR0_EL1 controls:
>   * The identity mapping,
>   * EFI runtime code.
> 
> It is possible to run a kernel with an identity mapping that has a
> larger VA size than userspace (and for this case __cpu_set_tcr_t0sz()
> would set TCR_EL1.T0SZ as appropriate). However, when the conditions for
> 52-bit userspace are met; it is possible to keep TCR_EL1.T0SZ fixed at
> 12. Thus in this patch, the TCR_EL1.T0SZ size changing logic is
> disabled.
> 
> Signed-off-by: Steve Capper <steve.capper@arm.com>
> 
> ---
> 
> Changed in V4, pgd_index logic removed as we offset ttbr1 instead
> ---
>   arch/arm64/Kconfig                   |  4 ++++
>   arch/arm64/include/asm/assembler.h   |  7 +++----
>   arch/arm64/include/asm/mmu_context.h |  3 +++
>   arch/arm64/include/asm/processor.h   | 14 +++++++++-----
>   arch/arm64/kernel/head.S             | 13 +++++++++++++
>   arch/arm64/mm/fault.c                |  2 +-
>   arch/arm64/mm/mmu.c                  |  1 +
>   arch/arm64/mm/proc.S                 | 10 +++++++++-
>   8 files changed, 43 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 787d7850e064..eab02d24f5d1 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -709,6 +709,10 @@ config ARM64_PA_BITS_52
>   
>   endchoice
>   
> +config ARM64_52BIT_VA
> +	def_bool y
> +	depends on ARM64_VA_BITS_48 && ARM64_64K_PAGES
> +
>   config ARM64_PA_BITS
>   	int
>   	default 48 if ARM64_PA_BITS_48
> diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
> index e2fe378d2a63..243ec4f0c00f 100644
> --- a/arch/arm64/include/asm/assembler.h
> +++ b/arch/arm64/include/asm/assembler.h
> @@ -342,11 +342,10 @@ alternative_endif
>   	.endm
>   
>   /*
> - * tcr_set_idmap_t0sz - update TCR.T0SZ so that we can load the ID map
> + * tcr_set_t0sz - update TCR.T0SZ so that we can load the ID map
>    */
> -	.macro	tcr_set_idmap_t0sz, valreg, tmpreg
> -	ldr_l	\tmpreg, idmap_t0sz
> -	bfi	\valreg, \tmpreg, #TCR_T0SZ_OFFSET, #TCR_TxSZ_WIDTH
> +	.macro	tcr_set_t0sz, valreg, t0sz
> +	bfi	\valreg, \t0sz, #TCR_T0SZ_OFFSET, #TCR_TxSZ_WIDTH
>   	.endm
>   
>   /*
> diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
> index 1e58bf58c22b..b125fafc611b 100644
> --- a/arch/arm64/include/asm/mmu_context.h
> +++ b/arch/arm64/include/asm/mmu_context.h
> @@ -72,6 +72,9 @@ extern u64 idmap_ptrs_per_pgd;
>   
>   static inline bool __cpu_uses_extended_idmap(void)
>   {
> +	if (IS_ENABLED(CONFIG_ARM64_52BIT_VA))
> +		return false;
> +
>   	return unlikely(idmap_t0sz != TCR_T0SZ(VA_BITS));
>   }
>   
> diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
> index fe95fd8b065e..b363fc705be4 100644
> --- a/arch/arm64/include/asm/processor.h
> +++ b/arch/arm64/include/asm/processor.h
> @@ -19,11 +19,12 @@
>   #ifndef __ASM_PROCESSOR_H
>   #define __ASM_PROCESSOR_H
>   
> -#define TASK_SIZE_64		(UL(1) << VA_BITS)
> -
> -#define KERNEL_DS	UL(-1)
> -#define USER_DS		(TASK_SIZE_64 - 1)
> -
> +#define KERNEL_DS		UL(-1)
> +#ifdef CONFIG_ARM64_52BIT_VA
> +#define USER_DS			((UL(1) << 52) - 1)
> +#else
> +#define USER_DS			((UL(1) << VA_BITS) - 1)
> +#endif /* CONFIG_ARM64_52IT_VA */
>   #ifndef __ASSEMBLY__
>   #ifdef __KERNEL__
>   
> @@ -48,6 +49,9 @@
>   
>   #define DEFAULT_MAP_WINDOW_64	(UL(1) << VA_BITS)
>   
> +extern u64 vabits_user;
> +#define TASK_SIZE_64		(UL(1) << vabits_user)
> +
>   #ifdef CONFIG_COMPAT
>   #define TASK_SIZE_32		UL(0x100000000)
>   #define TASK_SIZE		(test_thread_flag(TIF_32BIT) ? \
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index f60081be9a1b..5bc776b8ee5e 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -318,6 +318,19 @@ __create_page_tables:
>   	adrp	x0, idmap_pg_dir
>   	adrp	x3, __idmap_text_start		// __pa(__idmap_text_start)
>   
> +#ifdef CONFIG_ARM64_52BIT_VA
> +	mrs_s	x6, SYS_ID_AA64MMFR2_EL1
> +	and	x6, x6, #(0xf << ID_AA64MMFR2_LVA_SHIFT)
> +	mov	x5, #52
> +	cbnz	x6, 1f
> +#endif
> +	mov	x5, #VA_BITS
> +1:
> +	adr_l	x6, vabits_user
> +	str	x5, [x6]
> +	dmb	sy
> +	dc	ivac, x6		// Invalidate potentially stale cache line
> +

I think we may need a check for the secondary CPUs to make sure that they have
the 52bit support once the boot CPU has decided to use the feature and fail the
CPU bring up (just like we do for the granule support).

Suzuki

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH V4 5/6] arm64: mm: introduce 52-bit userspace support

[Steve Capper]

On Wed, Dec 05, 2018 at 06:22:27PM +0000, Suzuki K Poulose wrote:
> Hi Steve,
> 
[...] 
> I think we may need a check for the secondary CPUs to make sure that they have
> the 52bit support once the boot CPU has decided to use the feature and fail the
> CPU bring up (just like we do for the granule support).
> 
> Suzuki

Hi Suzuki,
I have just written a patch to detect a mismatch between 52-bit VA that
is being tested now.

As 52-bit kernel VA support is coming in future, the patch checks for a
mismatch during the secondary boot path and, if one is found, prevents
the secondary from booting (and displays an error message to the user).

Cheers,
-- 
Steve

Re: [PATCH V4 5/6] arm64: mm: introduce 52-bit userspace support

[Steve Capper]

On Wed, Dec 05, 2018 at 06:22:27PM +0000, Suzuki K Poulose wrote:
> Hi Steve,
> 
[...] 
> I think we may need a check for the secondary CPUs to make sure that they have
> the 52bit support once the boot CPU has decided to use the feature and fail the
> CPU bring up (just like we do for the granule support).
> 
> Suzuki

Hi Suzuki,
I have just written a patch to detect a mismatch between 52-bit VA that
is being tested now.

As 52-bit kernel VA support is coming in future, the patch checks for a
mismatch during the secondary boot path and, if one is found, prevents
the secondary from booting (and displays an error message to the user).

Cheers,
-- 
Steve

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH V4 5/6] arm64: mm: introduce 52-bit userspace support

[Suzuki K Poulose]

On 06/12/2018 12:26, Steve Capper wrote:
> On Wed, Dec 05, 2018 at 06:22:27PM +0000, Suzuki K Poulose wrote:
>> Hi Steve,
>>
> [...]
>> I think we may need a check for the secondary CPUs to make sure that they have
>> the 52bit support once the boot CPU has decided to use the feature and fail the
>> CPU bring up (just like we do for the granule support).
>>
>> Suzuki
> 
> Hi Suzuki,
> I have just written a patch to detect a mismatch between 52-bit VA that
> is being tested now.
> 
> As 52-bit kernel VA support is coming in future, the patch checks for a
> mismatch during the secondary boot path and, if one is found, prevents
> the secondary from booting (and displays an error message to the user).

Right now, it is the boot CPU which decides the Userspace 52bit VA, isn't it ?
Irrespective of the kernel VA support, the userspace must be able to run on
all the CPUs on the system, right ? So don't we need it now, with this series ?


Cheers
Suzuki

Re: [PATCH V4 5/6] arm64: mm: introduce 52-bit userspace support

[Suzuki K Poulose]

On 06/12/2018 12:26, Steve Capper wrote:
> On Wed, Dec 05, 2018 at 06:22:27PM +0000, Suzuki K Poulose wrote:
>> Hi Steve,
>>
> [...]
>> I think we may need a check for the secondary CPUs to make sure that they have
>> the 52bit support once the boot CPU has decided to use the feature and fail the
>> CPU bring up (just like we do for the granule support).
>>
>> Suzuki
> 
> Hi Suzuki,
> I have just written a patch to detect a mismatch between 52-bit VA that
> is being tested now.
> 
> As 52-bit kernel VA support is coming in future, the patch checks for a
> mismatch during the secondary boot path and, if one is found, prevents
> the secondary from booting (and displays an error message to the user).

Right now, it is the boot CPU which decides the Userspace 52bit VA, isn't it ?
Irrespective of the kernel VA support, the userspace must be able to run on
all the CPUs on the system, right ? So don't we need it now, with this series ?


Cheers
Suzuki

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH V4 5/6] arm64: mm: introduce 52-bit userspace support

[Steve Capper]

On Thu, Dec 06, 2018 at 02:35:20PM +0000, Suzuki K Poulose wrote:
> 
> 
> On 06/12/2018 12:26, Steve Capper wrote:
> > On Wed, Dec 05, 2018 at 06:22:27PM +0000, Suzuki K Poulose wrote:
> > > Hi Steve,
> > > 
> > [...]
> > > I think we may need a check for the secondary CPUs to make sure that they have
> > > the 52bit support once the boot CPU has decided to use the feature and fail the
> > > CPU bring up (just like we do for the granule support).
> > > 
> > > Suzuki
> > 
> > Hi Suzuki,
> > I have just written a patch to detect a mismatch between 52-bit VA that
> > is being tested now.
> > 
> > As 52-bit kernel VA support is coming in future, the patch checks for a
> > mismatch during the secondary boot path and, if one is found, prevents
> > the secondary from booting (and displays an error message to the user).
> 
> Right now, it is the boot CPU which decides the Userspace 52bit VA, isn't it ?
> Irrespective of the kernel VA support, the userspace must be able to run on
> all the CPUs on the system, right ? So don't we need it now, with this series ?

Hi Suzuki,

Yes the boot CPU determines vabits_user. My idea was to have the
secondary CPUs check to see if vabits_user was 52, and if so, then check
to see if it's capable of supporting 52-bit. If not, then it stops
booting (and sets a flag to indicate why).

This check will be valid for 52-bit userspace support and also valid for
52-bit kernel support (as the check is performed before the secondary
mmu is enabled). I didn't want to write a higher level detection
routine for the userspace support and then have to re-write it later
when introducing 52-bit kernel support.

I'm happy to do what works though, I thought this way was simplest :-).

Cheers,
-- 
Steve

Re: [PATCH V4 5/6] arm64: mm: introduce 52-bit userspace support

[Steve Capper]

On Thu, Dec 06, 2018 at 02:35:20PM +0000, Suzuki K Poulose wrote:
> 
> 
> On 06/12/2018 12:26, Steve Capper wrote:
> > On Wed, Dec 05, 2018 at 06:22:27PM +0000, Suzuki K Poulose wrote:
> > > Hi Steve,
> > > 
> > [...]
> > > I think we may need a check for the secondary CPUs to make sure that they have
> > > the 52bit support once the boot CPU has decided to use the feature and fail the
> > > CPU bring up (just like we do for the granule support).
> > > 
> > > Suzuki
> > 
> > Hi Suzuki,
> > I have just written a patch to detect a mismatch between 52-bit VA that
> > is being tested now.
> > 
> > As 52-bit kernel VA support is coming in future, the patch checks for a
> > mismatch during the secondary boot path and, if one is found, prevents
> > the secondary from booting (and displays an error message to the user).
> 
> Right now, it is the boot CPU which decides the Userspace 52bit VA, isn't it ?
> Irrespective of the kernel VA support, the userspace must be able to run on
> all the CPUs on the system, right ? So don't we need it now, with this series ?

Hi Suzuki,

Yes the boot CPU determines vabits_user. My idea was to have the
secondary CPUs check to see if vabits_user was 52, and if so, then check
to see if it's capable of supporting 52-bit. If not, then it stops
booting (and sets a flag to indicate why).

This check will be valid for 52-bit userspace support and also valid for
52-bit kernel support (as the check is performed before the secondary
mmu is enabled). I didn't want to write a higher level detection
routine for the userspace support and then have to re-write it later
when introducing 52-bit kernel support.

I'm happy to do what works though, I thought this way was simplest :-).

Cheers,
-- 
Steve

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH V4 6/6] arm64: mm: Allow forcing all userspace addresses to 52-bit

[Steve Capper]

On arm64 52-bit VAs are provided to userspace when a hint is supplied to
mmap. This helps maintain compatibility with software that expects at
most 48-bit VAs to be returned.

In order to help identify software that has 48-bit VA assumptions, this
patch allows one to compile a kernel where 52-bit VAs are returned by
default on HW that supports it.

This feature is intended to be for development systems only.

Signed-off-by: Steve Capper <steve.capper@arm.com>
---
 arch/arm64/Kconfig                 | 13 +++++++++++++
 arch/arm64/include/asm/elf.h       |  4 ++++
 arch/arm64/include/asm/processor.h |  9 ++++++++-
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index eab02d24f5d1..9f50dc8af110 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1165,6 +1165,19 @@ config ARM64_CNP
 	  at runtime, and does not affect PEs that do not implement
 	  this feature.
 
+config ARM64_FORCE_52BIT
+	bool "Force 52-bit virtual addresses for userspace"
+	depends on ARM64_52BIT_VA && EXPERT
+	help
+	  For systems with 52-bit userspace VAs enabled, the kernel will attempt
+	  to maintain compatibility with older software by providing 48-bit VAs
+	  unless a hint is supplied to mmap.
+
+	  This configuration option disables the 48-bit compatibility logic, and
+	  forces all userspace addresses to be 52-bit on HW that supports it. One
+	  should only enable this configuration option for stress testing userspace
+	  memory management code. If unsure say N here.
+
 endmenu
 
 config ARM64_SVE
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index bc9bd9e77d9d..6adc1a90e7e6 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -117,7 +117,11 @@
  * 64-bit, this is above 4GB to leave the entire 32-bit address
  * space open for things that want to use the area for 32-bit pointers.
  */
+#ifdef CONFIG_ARM64_FORCE_52BIT
+#define ELF_ET_DYN_BASE		(2 * TASK_SIZE_64 / 3)
+#else
 #define ELF_ET_DYN_BASE		(2 * DEFAULT_MAP_WINDOW_64 / 3)
+#endif /* CONFIG_ARM64_FORCE_52BIT */
 
 #ifndef __ASSEMBLY__
 
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index b363fc705be4..9abd91570b5b 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -65,8 +65,13 @@ extern u64 vabits_user;
 #define DEFAULT_MAP_WINDOW	DEFAULT_MAP_WINDOW_64
 #endif /* CONFIG_COMPAT */
 
-#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(DEFAULT_MAP_WINDOW / 4))
+#ifdef CONFIG_ARM64_FORCE_52BIT
+#define STACK_TOP_MAX		TASK_SIZE_64
+#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(TASK_SIZE / 4))
+#else
 #define STACK_TOP_MAX		DEFAULT_MAP_WINDOW_64
+#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(DEFAULT_MAP_WINDOW / 4))
+#endif /* CONFIG_ARM64_FORCE_52BIT */
 
 #ifdef CONFIG_COMPAT
 #define AARCH32_VECTORS_BASE	0xffff0000
@@ -76,12 +81,14 @@ extern u64 vabits_user;
 #define STACK_TOP		STACK_TOP_MAX
 #endif /* CONFIG_COMPAT */
 
+#ifndef CONFIG_ARM64_FORCE_52BIT
 #define arch_get_mmap_end(addr) ((addr > DEFAULT_MAP_WINDOW) ? TASK_SIZE :\
 				DEFAULT_MAP_WINDOW)
 
 #define arch_get_mmap_base(addr, base) ((addr > DEFAULT_MAP_WINDOW) ? \
 					base + TASK_SIZE - DEFAULT_MAP_WINDOW :\
 					base)
+#endif /* CONFIG_ARM64_FORCE_52BIT */
 
 extern phys_addr_t arm64_dma_phys_limit;
 #define ARCH_LOW_ADDRESS_LIMIT	(arm64_dma_phys_limit - 1)
-- 
2.19.2

[PATCH V4 6/6] arm64: mm: Allow forcing all userspace addresses to 52-bit

[Steve Capper]

On arm64 52-bit VAs are provided to userspace when a hint is supplied to
mmap. This helps maintain compatibility with software that expects at
most 48-bit VAs to be returned.

In order to help identify software that has 48-bit VA assumptions, this
patch allows one to compile a kernel where 52-bit VAs are returned by
default on HW that supports it.

This feature is intended to be for development systems only.

Signed-off-by: Steve Capper <steve.capper@arm.com>
---
 arch/arm64/Kconfig                 | 13 +++++++++++++
 arch/arm64/include/asm/elf.h       |  4 ++++
 arch/arm64/include/asm/processor.h |  9 ++++++++-
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index eab02d24f5d1..9f50dc8af110 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1165,6 +1165,19 @@ config ARM64_CNP
 	  at runtime, and does not affect PEs that do not implement
 	  this feature.
 
+config ARM64_FORCE_52BIT
+	bool "Force 52-bit virtual addresses for userspace"
+	depends on ARM64_52BIT_VA && EXPERT
+	help
+	  For systems with 52-bit userspace VAs enabled, the kernel will attempt
+	  to maintain compatibility with older software by providing 48-bit VAs
+	  unless a hint is supplied to mmap.
+
+	  This configuration option disables the 48-bit compatibility logic, and
+	  forces all userspace addresses to be 52-bit on HW that supports it. One
+	  should only enable this configuration option for stress testing userspace
+	  memory management code. If unsure say N here.
+
 endmenu
 
 config ARM64_SVE
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index bc9bd9e77d9d..6adc1a90e7e6 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -117,7 +117,11 @@
  * 64-bit, this is above 4GB to leave the entire 32-bit address
  * space open for things that want to use the area for 32-bit pointers.
  */
+#ifdef CONFIG_ARM64_FORCE_52BIT
+#define ELF_ET_DYN_BASE		(2 * TASK_SIZE_64 / 3)
+#else
 #define ELF_ET_DYN_BASE		(2 * DEFAULT_MAP_WINDOW_64 / 3)
+#endif /* CONFIG_ARM64_FORCE_52BIT */
 
 #ifndef __ASSEMBLY__
 
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index b363fc705be4..9abd91570b5b 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -65,8 +65,13 @@ extern u64 vabits_user;
 #define DEFAULT_MAP_WINDOW	DEFAULT_MAP_WINDOW_64
 #endif /* CONFIG_COMPAT */
 
-#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(DEFAULT_MAP_WINDOW / 4))
+#ifdef CONFIG_ARM64_FORCE_52BIT
+#define STACK_TOP_MAX		TASK_SIZE_64
+#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(TASK_SIZE / 4))
+#else
 #define STACK_TOP_MAX		DEFAULT_MAP_WINDOW_64
+#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(DEFAULT_MAP_WINDOW / 4))
+#endif /* CONFIG_ARM64_FORCE_52BIT */
 
 #ifdef CONFIG_COMPAT
 #define AARCH32_VECTORS_BASE	0xffff0000
@@ -76,12 +81,14 @@ extern u64 vabits_user;
 #define STACK_TOP		STACK_TOP_MAX
 #endif /* CONFIG_COMPAT */
 
+#ifndef CONFIG_ARM64_FORCE_52BIT
 #define arch_get_mmap_end(addr) ((addr > DEFAULT_MAP_WINDOW) ? TASK_SIZE :\
 				DEFAULT_MAP_WINDOW)
 
 #define arch_get_mmap_base(addr, base) ((addr > DEFAULT_MAP_WINDOW) ? \
 					base + TASK_SIZE - DEFAULT_MAP_WINDOW :\
 					base)
+#endif /* CONFIG_ARM64_FORCE_52BIT */
 
 extern phys_addr_t arm64_dma_phys_limit;
 #define ARCH_LOW_ADDRESS_LIMIT	(arm64_dma_phys_limit - 1)
-- 
2.19.2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH V4 6/6] arm64: mm: Allow forcing all userspace addresses to 52-bit

[Catalin Marinas]

On Wed, Dec 05, 2018 at 04:41:45PM +0000, Steve Capper wrote:
> On arm64 52-bit VAs are provided to userspace when a hint is supplied to
> mmap. This helps maintain compatibility with software that expects at
> most 48-bit VAs to be returned.
> 
> In order to help identify software that has 48-bit VA assumptions, this
> patch allows one to compile a kernel where 52-bit VAs are returned by
> default on HW that supports it.
> 
> This feature is intended to be for development systems only.
> 
> Signed-off-by: Steve Capper <steve.capper@arm.com>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Re: [PATCH V4 6/6] arm64: mm: Allow forcing all userspace addresses to 52-bit

[Catalin Marinas]

On Wed, Dec 05, 2018 at 04:41:45PM +0000, Steve Capper wrote:
> On arm64 52-bit VAs are provided to userspace when a hint is supplied to
> mmap. This helps maintain compatibility with software that expects at
> most 48-bit VAs to be returned.
> 
> In order to help identify software that has 48-bit VA assumptions, this
> patch allows one to compile a kernel where 52-bit VAs are returned by
> default on HW that supports it.
> 
> This feature is intended to be for development systems only.
> 
> Signed-off-by: Steve Capper <steve.capper@arm.com>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH V4 6/6] arm64: mm: Allow forcing all userspace addresses to 52-bit

[Steve Capper]

On Thu, Dec 06, 2018 at 11:51:33AM +0000, Catalin Marinas wrote:
> On Wed, Dec 05, 2018 at 04:41:45PM +0000, Steve Capper wrote:
> > On arm64 52-bit VAs are provided to userspace when a hint is supplied to
> > mmap. This helps maintain compatibility with software that expects at
> > most 48-bit VAs to be returned.
> > 
> > In order to help identify software that has 48-bit VA assumptions, this
> > patch allows one to compile a kernel where 52-bit VAs are returned by
> > default on HW that supports it.
> > 
> > This feature is intended to be for development systems only.
> > 
> > Signed-off-by: Steve Capper <steve.capper@arm.com>
> 
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Thanks Catalin.

Re: [PATCH V4 6/6] arm64: mm: Allow forcing all userspace addresses to 52-bit

[Steve Capper]

On Thu, Dec 06, 2018 at 11:51:33AM +0000, Catalin Marinas wrote:
> On Wed, Dec 05, 2018 at 04:41:45PM +0000, Steve Capper wrote:
> > On arm64 52-bit VAs are provided to userspace when a hint is supplied to
> > mmap. This helps maintain compatibility with software that expects at
> > most 48-bit VAs to be returned.
> > 
> > In order to help identify software that has 48-bit VA assumptions, this
> > patch allows one to compile a kernel where 52-bit VAs are returned by
> > default on HW that supports it.
> > 
> > This feature is intended to be for development systems only.
> > 
> > Signed-off-by: Steve Capper <steve.capper@arm.com>
> 
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Thanks Catalin.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel