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From: Ard Biesheuvel <ardb@google.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Ard Biesheuvel <ardb@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	 Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	 Ryan Roberts <ryan.roberts@arm.com>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	 Kees Cook <keescook@chromium.org>
Subject: [PATCH v6 09/41] arm64: mm: Reclaim unused vmemmap region for vmalloc use
Date: Wed, 29 Nov 2023 12:16:05 +0100	[thread overview]
Message-ID: <20231129111555.3594833-52-ardb@google.com> (raw)
In-Reply-To: <20231129111555.3594833-43-ardb@google.com>

From: Ard Biesheuvel <ardb@kernel.org>

The vmemmap array is statically sized based on the maximum supported
size of the virtual address space, but it is located inside the upper VA
region, which is statically sized based on the *minimum* supported size
of the VA space. This doesn't matter much when using 64k pages, which is
the only configuration that currently supports 52-bit virtual
addressing.

However, upcoming LPA2 support will change this picture somewhat, as in
that case, the vmemmap array will take up more than 25% of the upper VA
region when using 4k pages. Given that most of this space is never used
when running on a system that does not support 52-bit virtual
addressing, let's reclaim the unused vmemmap area in that case.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/include/asm/pgtable.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 8d30e2787b1f..5b5bedfa320e 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -18,11 +18,15 @@
  * VMALLOC range.
  *
  * VMALLOC_START: beginning of the kernel vmalloc space
- * VMALLOC_END: extends to the available space below vmemmap, PCI I/O space
- *	and fixed mappings
+ * VMALLOC_END: extends to the available space below vmemmap
  */
 #define VMALLOC_START		(MODULES_END)
+#if VA_BITS == VA_BITS_MIN
 #define VMALLOC_END		(VMEMMAP_START - SZ_8M)
+#else
+#define VMEMMAP_UNUSED_NPAGES	((_PAGE_OFFSET(vabits_actual) - PAGE_OFFSET) >> PAGE_SHIFT)
+#define VMALLOC_END		(VMEMMAP_START + VMEMMAP_UNUSED_NPAGES * sizeof(struct page) - SZ_8M)
+#endif
 
 #define vmemmap			((struct page *)VMEMMAP_START - (memstart_addr >> PAGE_SHIFT))
 
-- 
2.43.0.rc1.413.gea7ed67945-goog


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  parent reply	other threads:[~2023-11-29 12:31 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-29 11:15 [PATCH v6 00/41] arm64: Reorganize kernel VA space for LPA2 Ard Biesheuvel
2023-11-29 11:15 ` [PATCH v6 01/41] arm64: kernel: Disable latent_entropy GCC plugin in early C runtime Ard Biesheuvel
2023-11-30  4:44   ` Anshuman Khandual
2023-11-29 11:15 ` [PATCH v6 02/41] arm64: mm: Take potential load offset into account when KASLR is off Ard Biesheuvel
2023-11-30  5:23   ` Anshuman Khandual
2023-12-04 14:12   ` Mark Rutland
2023-12-04 15:40     ` Ard Biesheuvel
2023-11-29 11:15 ` [PATCH v6 03/41] arm64: mm: get rid of kimage_vaddr global variable Ard Biesheuvel
2023-11-30  5:38   ` Anshuman Khandual
2023-12-04 14:37     ` Mark Rutland
2023-12-05  2:26       ` Anshuman Khandual
2023-11-29 11:16 ` [PATCH v6 04/41] arm64: mm: Move PCI I/O emulation region above the vmemmap region Ard Biesheuvel
2023-11-30  7:59   ` Anshuman Khandual
2023-11-30  8:02     ` Ard Biesheuvel
2023-11-30  8:52       ` Anshuman Khandual
2023-11-30  8:56         ` Ard Biesheuvel
2023-12-11 13:57   ` Mark Rutland
2023-12-11 14:10     ` Ard Biesheuvel
2023-12-11 14:21       ` Mark Rutland
2023-11-29 11:16 ` [PATCH v6 05/41] arm64: mm: Move fixmap region above " Ard Biesheuvel
2023-12-11 14:23   ` Mark Rutland
2023-11-29 11:16 ` [PATCH v6 06/41] arm64: ptdump: Allow all region boundaries to be defined at boot time Ard Biesheuvel
2023-12-11 14:15   ` Mark Rutland
2023-11-29 11:16 ` [PATCH v6 07/41] arm64: ptdump: Discover start of vmemmap region at runtime Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 08/41] arm64: vmemmap: Avoid base2 order of struct page size to dimension region Ard Biesheuvel
2023-12-11 14:35   ` Mark Rutland
2023-12-12 21:34     ` Ard Biesheuvel
2023-11-29 11:16 ` Ard Biesheuvel [this message]
2023-11-29 11:16 ` [PATCH v6 10/41] arm64: kaslr: Adjust randomization range dynamically Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 11/41] arm64: kernel: Manage absolute relocations in code built under pi/ Ard Biesheuvel
2023-11-29 12:27   ` Marc Zyngier
2023-11-29 12:46     ` Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 12/41] arm64: kernel: Don't rely on objcopy to make code under pi/ __init Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 13/41] arm64: head: move relocation handling to C code Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 14/41] arm64: idreg-override: Omit non-NULL checks for override pointer Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 15/41] arm64: idreg-override: Prepare for place relative reloc patching Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 16/41] arm64: idreg-override: Avoid parameq() and parameqn() Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 17/41] arm64: idreg-override: avoid strlen() to check for empty strings Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 18/41] arm64: idreg-override: Avoid sprintf() for simple string concatenation Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 19/41] arm64: idreg-override: Avoid kstrtou64() to parse a single hex digit Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 20/41] arm64/kernel: Move 'nokaslr' parsing out of early idreg code Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 21/41] arm64: idreg-override: Move to early mini C runtime Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 22/41] arm64: kernel: Remove early fdt remap code Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 23/41] arm64: head: Clear BSS and the kernel page tables in one go Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 24/41] arm64: Move feature overrides into the BSS section Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 25/41] arm64: head: Run feature override detection before mapping the kernel Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 26/41] arm64: head: move dynamic shadow call stack patching into early C runtime Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 27/41] arm64: cpufeature: Add helper to test for CPU feature overrides Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 28/41] arm64: kaslr: Use feature override instead of parsing the cmdline again Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 29/41] arm64: idreg-override: Create a pseudo feature for rodata=off Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 30/41] arm64: Add helpers to probe local CPU for PAC and BTI support Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 31/41] arm64: head: allocate more pages for the kernel mapping Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 32/41] arm64: head: move memstart_offset_seed handling to C code Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 33/41] arm64: mm: Make kaslr_requires_kpti() a static inline Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 34/41] arm64: mmu: Make __cpu_replace_ttbr1() out of line Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 35/41] arm64: head: Move early kernel mapping routines into C code Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 36/41] arm64: mm: Use 48-bit virtual addressing for the permanent ID map Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 37/41] arm64: pgtable: Decouple PGDIR size macros from PGD/PUD/PMD levels Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 38/41] arm64: kernel: Create initial ID map from C code Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 39/41] arm64: mm: avoid fixmap for early swapper_pg_dir updates Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 40/41] arm64: mm: omit redundant remap of kernel image Ard Biesheuvel
2023-11-29 11:16 ` [PATCH v6 41/41] arm64: Revert "mm: provide idmap pointer to cpu_replace_ttbr1()" Ard Biesheuvel
2023-12-12 17:20 ` [PATCH v6 00/41] arm64: Reorganize kernel VA space for LPA2 Will Deacon

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