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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,
	catalin.marinas@arm.com, bhsharma@redhat.com,
	Steve Capper <steve.capper@arm.com>,
	maz@kernel.org, will@kernel.org
Subject: [PATCH V4 09/11] arm64: mm: Modify calculation of VMEMMAP_SIZE
Date: Mon, 29 Jul 2019 17:21:15 +0100	[thread overview]
Message-ID: <20190729162117.832-10-steve.capper@arm.com> (raw)
In-Reply-To: <20190729162117.832-1-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).

Signed-off-by: Steve Capper <steve.capper@arm.com>
---
 arch/arm64/include/asm/memory.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 93341f4fe840..aa7186006ee5 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -26,8 +26,15 @@
 /*
  * 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
-- 
2.20.1


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  parent reply	other threads:[~2019-07-29 16:26 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-29 16:21 [PATCH V4 00/11] 52-bit kernel + user VAs Steve Capper
2019-07-29 16:21 ` [PATCH V4 01/11] arm64: mm: Remove bit-masking optimisations for PAGE_OFFSET and VMEMMAP_START Steve Capper
2019-08-05 11:07   ` Catalin Marinas
2019-07-29 16:21 ` [PATCH V4 02/11] arm64: mm: Flip kernel VA space Steve Capper
2019-08-05 11:29   ` Catalin Marinas
2019-08-05 11:50     ` Steve Capper
2019-07-29 16:21 ` [PATCH V4 03/11] arm64: kasan: Switch to using KASAN_SHADOW_OFFSET Steve Capper
2019-08-05 16:37   ` Catalin Marinas
2019-08-06  9:05     ` Steve Capper
2019-07-29 16:21 ` [PATCH V4 04/11] arm64: dump: De-constify VA_START and KASAN_SHADOW_START Steve Capper
2019-08-05 16:38   ` Catalin Marinas
2019-07-29 16:21 ` [PATCH V4 05/11] arm64: mm: Introduce VA_BITS_MIN Steve Capper
2019-08-05 17:17   ` Catalin Marinas
2019-08-05 17:20   ` Catalin Marinas
2019-08-06  9:11     ` Steve Capper
2019-07-29 16:21 ` [PATCH V4 06/11] arm64: mm: Introduce VA_BITS_ACTUAL Steve Capper
2019-08-05 17:26   ` Catalin Marinas
2019-08-06 11:32     ` Steve Capper
2019-08-06 14:48       ` Catalin Marinas
2019-08-07 13:27         ` Steve Capper
2019-07-29 16:21 ` [PATCH V4 07/11] arm64: mm: Logic to make offset_ttbr1 conditional Steve Capper
2019-08-05 17:06   ` Catalin Marinas
2019-07-29 16:21 ` [PATCH V4 08/11] arm64: mm: Separate out vmemmap Steve Capper
2019-08-05 17:07   ` Catalin Marinas
2019-07-29 16:21 ` Steve Capper [this message]
2019-08-05 17:10   ` [PATCH V4 09/11] arm64: mm: Modify calculation of VMEMMAP_SIZE Catalin Marinas
2019-07-29 16:21 ` [PATCH V4 10/11] arm64: mm: Introduce 52-bit Kernel VAs Steve Capper
2019-08-05 17:27   ` Catalin Marinas
2019-08-06 14:55   ` Catalin Marinas
2019-08-06 14:58     ` Catalin Marinas
2019-07-29 16:21 ` [PATCH V4 11/11] docs: arm64: Add layout and 52-bit info to memory document Steve Capper
2019-08-06 15:27   ` Catalin Marinas
2019-08-07 13:29     ` Steve Capper
2019-08-07 14:55       ` Will Deacon
2019-08-07 15:57         ` Steve Capper

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