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From: Steve Capper <steve.capper@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: crecklin@redhat.com, ard.biesheuvel@linaro.org,
	marc.zyngier@arm.com, catalin.marinas@arm.com,
	bhsharma@redhat.com, will.deacon@arm.com
Subject: [PATCH v2 10/12] arm64: mm: Modify calculation of VMEMMAP_SIZE
Date: Tue, 28 May 2019 17:10:24 +0100	[thread overview]
Message-ID: <20190528161026.13193-11-steve.capper@arm.com> (raw)
In-Reply-To: <20190528161026.13193-1-steve.capper@arm.com>

In a later patch we will need to have a slightly larger VMEMMAP region
to accommodate boot time selection between 48/52-bit kernel VAs.

This patch modifies the formula for computing VMEMMAP_SIZE to depend
explicitly on the PAGE_OFFSET and start of kernel addressable memory.
(This allows for a slightly larger direct linear map in future).

Also this patch removes the use of bitmasking in the computation of
_page_to_voff as this can cause problems if we decide to move regions
around in future.

Signed-off-by: Steve Capper <steve.capper@arm.com>
---
 arch/arm64/include/asm/memory.h | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index c02373035533..e9af8aa36612 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -37,8 +37,15 @@
 /*
  * VMEMMAP_SIZE - allows the whole linear region to be covered by
  *                a struct page array
+ *
+ * If we are configured with a 52-bit kernel VA then our VMEMMAP_SIZE
+ * neads to cover the memory region from the beginning of the 52-bit
+ * PAGE_OFFSET all the way to VA_START for 48-bit. This allows us to
+ * keep a constant PAGE_OFFSET and "fallback" to using the higher end
+ * of the VMEMMAP where 52-bit support is not available in hardware.
  */
-#define VMEMMAP_SIZE (UL(1) << (VA_BITS - PAGE_SHIFT - 1 + STRUCT_PAGE_MAX_SHIFT))
+#define VMEMMAP_SIZE ((_VA_START(VA_BITS_MIN) - PAGE_OFFSET) \
+			>> (PAGE_SHIFT - STRUCT_PAGE_MAX_SHIFT))
 
 /*
  * PAGE_OFFSET - the virtual address of the start of the linear map (top
@@ -319,7 +326,7 @@ static inline void *phys_to_virt(phys_addr_t x)
 #define _virt_addr_valid(kaddr)	pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
 #else
 #define __virt_to_pgoff(kaddr)	(((u64)(kaddr) & ~PAGE_OFFSET) / PAGE_SIZE * sizeof(struct page))
-#define __page_to_voff(kaddr)	(((u64)(kaddr) & ~VMEMMAP_START) * PAGE_SIZE / sizeof(struct page))
+#define __page_to_voff(kaddr)	(((u64)(kaddr) - VMEMMAP_START) * PAGE_SIZE / sizeof(struct page))
 
 #define page_to_virt(page)	({					\
 	unsigned long __addr =						\
-- 
2.20.1


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  parent reply	other threads:[~2019-05-28 16:13 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-28 16:10 [PATCH v2 00/12] 52-bit kernel + user VAs Steve Capper
2019-05-28 16:10 ` [PATCH v2 01/12] arm/arm64: KVM: Formalise end of direct linear map Steve Capper
2019-05-28 16:27   ` Marc Zyngier
2019-05-28 17:01     ` Steve Capper
2019-05-29  9:26       ` Steve Capper
2019-05-28 16:10 ` [PATCH v2 02/12] arm64: mm: Flip kernel VA space Steve Capper
2019-05-28 16:10 ` [PATCH v2 03/12] arm64: kasan: Switch to using KASAN_SHADOW_OFFSET Steve Capper
2019-05-28 16:10 ` [PATCH v2 04/12] arm64: mm: Replace fixed map BUILD_BUG_ON's with BUG_ON's Steve Capper
2019-05-28 17:07   ` Ard Biesheuvel
2019-05-28 17:11     ` Ard Biesheuvel
2019-05-29  9:28       ` Steve Capper
2019-05-28 16:10 ` [PATCH v2 05/12] arm64: dump: Make kernel page table dumper dynamic again Steve Capper
2019-05-28 16:10 ` [PATCH v2 06/12] arm64: mm: Introduce VA_BITS_MIN Steve Capper
2019-05-28 16:10 ` [PATCH v2 07/12] arm64: mm: Introduce VA_BITS_ACTUAL Steve Capper
2019-05-28 16:10 ` [PATCH v2 08/12] arm64: mm: Logic to make offset_ttbr1 conditional Steve Capper
2019-06-10 14:18   ` Catalin Marinas
2019-06-12 10:58     ` Steve Capper
2019-05-28 16:10 ` [PATCH v2 09/12] arm64: mm: Separate out vmemmap Steve Capper
2019-05-28 16:10 ` Steve Capper [this message]
2019-05-28 16:10 ` [PATCH v2 11/12] arm64: mm: Tweak PAGE_OFFSET logic Steve Capper
2019-05-28 16:10 ` [PATCH v2 12/12] arm64: mm: Introduce 52-bit Kernel VAs Steve Capper
2019-06-05 15:34   ` Catalin Marinas
2019-06-07 10:34     ` Steve Capper
2019-06-07 13:53 ` [PATCH v2 00/12] 52-bit kernel + user VAs Anshuman Khandual
2019-06-07 14:24   ` Steve Capper
2019-06-10 10:40 ` Bhupesh Sharma
2019-06-10 10:54   ` Catalin Marinas
2019-06-10 11:15     ` Bhupesh Sharma

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