arm64: mm: move vmemmap region right below the linear region
This moves the vmemmap region right below PAGE_OFFSET, aka the start of the linear region, and redefines its size to be a power of two. Due to the placement of PAGE_OFFSET in the middle of the address space, whose size is a power of two as well, this guarantees that virt to page conversions and vice versa can be implemented efficiently, by masking and shifting rather than ordinary arithmetic. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Ard Biesheuvel
Will Deacon
parent
e44308e62e
commit
3e1907d5bf
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@ -39,6 +39,21 @@
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*/
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#define PCI_IO_SIZE SZ_16M
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/*
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* Log2 of the upper bound of the size of a struct page. Used for sizing
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* the vmemmap region only, does not affect actual memory footprint.
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* We don't use sizeof(struct page) directly since taking its size here
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* requires its definition to be available at this point in the inclusion
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* chain, and it may not be a power of 2 in the first place.
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*/
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#define STRUCT_PAGE_MAX_SHIFT 6
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/*
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* VMEMMAP_SIZE - allows the whole linear region to be covered by
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* a struct page array
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*/
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#define VMEMMAP_SIZE (UL(1) << (VA_BITS - PAGE_SHIFT - 1 + STRUCT_PAGE_MAX_SHIFT))
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/*
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* PAGE_OFFSET - the virtual address of the start of the kernel image (top
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* (VA_BITS - 1))
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@ -54,7 +69,8 @@
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#define MODULES_END (MODULES_VADDR + MODULES_VSIZE)
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#define MODULES_VADDR (VA_START + KASAN_SHADOW_SIZE)
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#define MODULES_VSIZE (SZ_128M)
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#define PCI_IO_END (PAGE_OFFSET - SZ_2M)
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#define VMEMMAP_START (PAGE_OFFSET - VMEMMAP_SIZE)
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#define PCI_IO_END (VMEMMAP_START - SZ_2M)
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#define PCI_IO_START (PCI_IO_END - PCI_IO_SIZE)
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#define FIXADDR_TOP (PCI_IO_START - SZ_2M)
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#define TASK_SIZE_64 (UL(1) << VA_BITS)
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@ -24,20 +24,15 @@
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#include <asm/pgtable-prot.h>
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/*
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* VMALLOC and SPARSEMEM_VMEMMAP ranges.
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* VMALLOC range.
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*
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* VMEMAP_SIZE: allows the whole linear region to be covered by a struct page array
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* (rounded up to PUD_SIZE).
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* VMALLOC_START: beginning of the kernel vmalloc space
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* VMALLOC_END: extends to the available space below vmmemmap, PCI I/O space,
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* fixed mappings and modules
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* VMALLOC_END: extends to the available space below vmmemmap, PCI I/O space
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* and fixed mappings
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*/
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#define VMEMMAP_SIZE ALIGN((1UL << (VA_BITS - PAGE_SHIFT - 1)) * sizeof(struct page), PUD_SIZE)
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#define VMALLOC_START (MODULES_END)
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#define VMALLOC_END (PAGE_OFFSET - PUD_SIZE - VMEMMAP_SIZE - SZ_64K)
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#define VMEMMAP_START (VMALLOC_END + SZ_64K)
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#define vmemmap ((struct page *)VMEMMAP_START - (memstart_addr >> PAGE_SHIFT))
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#define FIRST_USER_ADDRESS 0UL
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@ -37,14 +37,14 @@ enum address_markers_idx {
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MODULES_END_NR,
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VMALLOC_START_NR,
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VMALLOC_END_NR,
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#ifdef CONFIG_SPARSEMEM_VMEMMAP
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VMEMMAP_START_NR,
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VMEMMAP_END_NR,
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#endif
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FIXADDR_START_NR,
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FIXADDR_END_NR,
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PCI_START_NR,
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PCI_END_NR,
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#ifdef CONFIG_SPARSEMEM_VMEMMAP
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VMEMMAP_START_NR,
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VMEMMAP_END_NR,
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#endif
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KERNEL_SPACE_NR,
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};
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@ -53,14 +53,14 @@ static struct addr_marker address_markers[] = {
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{ MODULES_END, "Modules end" },
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{ VMALLOC_START, "vmalloc() Area" },
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{ VMALLOC_END, "vmalloc() End" },
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#ifdef CONFIG_SPARSEMEM_VMEMMAP
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{ 0, "vmemmap start" },
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{ 0, "vmemmap end" },
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#endif
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{ FIXADDR_START, "Fixmap start" },
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{ FIXADDR_TOP, "Fixmap end" },
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{ PCI_IO_START, "PCI I/O start" },
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{ PCI_IO_END, "PCI I/O end" },
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#ifdef CONFIG_SPARSEMEM_VMEMMAP
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{ 0, "vmemmap start" },
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{ 0, "vmemmap end" },
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#endif
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{ PAGE_OFFSET, "Linear Mapping" },
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{ -1, NULL },
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};
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@ -412,6 +412,10 @@ void __init mem_init(void)
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MLK_ROUNDUP(__start_rodata, _etext),
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MLK_ROUNDUP(__init_begin, __init_end),
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MLK_ROUNDUP(_sdata, _edata));
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pr_cont(" fixed : 0x%16lx - 0x%16lx (%6ld KB)\n",
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MLK(FIXADDR_START, FIXADDR_TOP));
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pr_cont(" PCI I/O : 0x%16lx - 0x%16lx (%6ld MB)\n",
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MLM(PCI_IO_START, PCI_IO_END));
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#ifdef CONFIG_SPARSEMEM_VMEMMAP
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pr_cont(" vmemmap : 0x%16lx - 0x%16lx (%6ld GB maximum)\n"
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" 0x%16lx - 0x%16lx (%6ld MB actual)\n",
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@ -420,10 +424,6 @@ void __init mem_init(void)
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MLM((unsigned long)phys_to_page(memblock_start_of_DRAM()),
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(unsigned long)virt_to_page(high_memory)));
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#endif
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pr_cont(" fixed : 0x%16lx - 0x%16lx (%6ld KB)\n",
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MLK(FIXADDR_START, FIXADDR_TOP));
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pr_cont(" PCI I/O : 0x%16lx - 0x%16lx (%6ld MB)\n",
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MLM(PCI_IO_START, PCI_IO_END));
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pr_cont(" memory : 0x%16lx - 0x%16lx (%6ld MB)\n",
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MLM(__phys_to_virt(memblock_start_of_DRAM()),
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(unsigned long)high_memory));
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@ -440,6 +440,12 @@ void __init mem_init(void)
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BUILD_BUG_ON(TASK_SIZE_32 > TASK_SIZE_64);
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#endif
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/*
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* Make sure we chose the upper bound of sizeof(struct page)
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* correctly.
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*/
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BUILD_BUG_ON(sizeof(struct page) > (1 << STRUCT_PAGE_MAX_SHIFT));
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if (PAGE_SIZE >= 16384 && get_num_physpages() <= 128) {
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extern int sysctl_overcommit_memory;
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/*
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