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arm64: mm: make vmemmap region a projection of the linear region

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Now that we have reverted the introduction of the vmemmap struct page
pointer and the separate physvirt_offset, we can simplify things further,
and place the vmemmap region in the VA space in such a way that virtual
to page translations and vice versa can be implemented using a single
arithmetic shift.

One happy coincidence resulting from this is that the 48-bit/4k and
52-bit/64k configurations (which are assumed to be the two most
prevalent) end up with the same placement of the vmemmap region. In
a subsequent patch, we will take advantage of this, and unify the
memory maps even more.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Steve Capper <steve.capper@arm.com>
Link: https://lore.kernel.org/r/20201008153602.9467-4-ardb@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Ard Biesheuvel 2020-10-08 17:36:01 +02:00 committed by Catalin Marinas
parent f4693c2716
commit 8c96400d6a
3 changed files with 23 additions and 23 deletions
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30
Documentation/arm64/memory.rst
View File

@ -35,14 +35,14 @@ AArch64 Linux memory layout with 4KB pages + 4 levels (48-bit)::
[ ffff600000000000 ffff7fffffffffff ] 32TB [ kasan shadow region ]
ffff800000000000 ffff800007ffffff 128MB bpf jit region
ffff800008000000 ffff80000fffffff 128MB modules
ffff800010000000 fffffdffbffeffff 125TB vmalloc
fffffdffbfff0000 fffffdfffe5f8fff ~998MB [guard region]
fffffdfffe5f9000 fffffdfffe9fffff 4124KB fixed mappings
fffffdfffea00000 fffffdfffebfffff 2MB [guard region]
fffffdfffec00000 fffffdffffbfffff 16MB PCI I/O space
fffffdffffc00000 fffffdffffdfffff 2MB [guard region]
fffffdffffe00000 ffffffffffdfffff 2TB vmemmap
ffffffffffe00000 ffffffffffffffff 2MB [guard region]
ffff800010000000 fffffbffbffeffff 123TB vmalloc
fffffbffbfff0000 fffffbfffe7f8fff ~998MB [guard region]
fffffbfffe7f9000 fffffbfffebfffff 4124KB fixed mappings
fffffbfffec00000 fffffbfffedfffff 2MB [guard region]
fffffbfffee00000 fffffbffffdfffff 16MB PCI I/O space
fffffbffffe00000 fffffbffffffffff 2MB [guard region]
fffffc0000000000 fffffdffffffffff 2TB vmemmap
fffffe0000000000 ffffffffffffffff 2TB [guard region]
AArch64 Linux memory layout with 64KB pages + 3 levels (52-bit with HW support)::
@ -55,13 +55,13 @@ AArch64 Linux memory layout with 64KB pages + 3 levels (52-bit with HW support):
ffff800000000000 ffff800007ffffff 128MB bpf jit region
ffff800008000000 ffff80000fffffff 128MB modules
ffff800010000000 fffff81ffffeffff 120TB vmalloc
fffff81fffff0000 fffffc1ffe58ffff ~3TB [guard region]
fffffc1ffe590000 fffffc1ffe9fffff 4544KB fixed mappings
fffffc1ffea00000 fffffc1ffebfffff 2MB [guard region]
fffffc1ffec00000 fffffc1fffbfffff 16MB PCI I/O space
fffffc1fffc00000 fffffc1fffdfffff 2MB [guard region]
fffffc1fffe00000 ffffffffffdfffff 3968GB vmemmap
ffffffffffe00000 ffffffffffffffff 2MB [guard region]
fffff81fffff0000 fffffbfffe38ffff ~3TB [guard region]
fffffbfffe390000 fffffbfffebfffff 4544KB fixed mappings
fffffbfffec00000 fffffbfffedfffff 2MB [guard region]
fffffbfffee00000 fffffbffffdfffff 16MB PCI I/O space
fffffbffffe00000 fffffbffffffffff 2MB [guard region]
fffffc0000000000 ffffffdfffffffff ~4TB vmemmap
ffffffe000000000 ffffffffffffffff 128GB [guard region]
Translation table lookup with 4KB pages::

14
arch/arm64/include/asm/memory.h
View File

@ -30,8 +30,8 @@
* 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 ((_PAGE_END(VA_BITS_MIN) - PAGE_OFFSET) \
>> (PAGE_SHIFT - STRUCT_PAGE_MAX_SHIFT))
#define VMEMMAP_SHIFT (PAGE_SHIFT - STRUCT_PAGE_MAX_SHIFT)
#define VMEMMAP_SIZE ((_PAGE_END(VA_BITS_MIN) - PAGE_OFFSET) >> VMEMMAP_SHIFT)
/*
* PAGE_OFFSET - the virtual address of the start of the linear map, at the
@ -50,7 +50,7 @@
#define MODULES_END (MODULES_VADDR + MODULES_VSIZE)
#define MODULES_VADDR (BPF_JIT_REGION_END)
#define MODULES_VSIZE (SZ_128M)
#define VMEMMAP_START (-VMEMMAP_SIZE - SZ_2M)
#define VMEMMAP_START (-(UL(1) << (VA_BITS - VMEMMAP_SHIFT)))
#define VMEMMAP_END (VMEMMAP_START + VMEMMAP_SIZE)
#define PCI_IO_END (VMEMMAP_START - SZ_2M)
#define PCI_IO_START (PCI_IO_END - PCI_IO_SIZE)
@ -308,15 +308,13 @@ static inline void *phys_to_virt(phys_addr_t x)
#else
#define page_to_virt(x) ({ \
__typeof__(x) __page = x; \
u64 __idx = ((u64)__page - VMEMMAP_START) / sizeof(struct page);\
u64 __addr = PAGE_OFFSET + (__idx * PAGE_SIZE); \
u64 __addr = (u64)__page << VMEMMAP_SHIFT; \
(void *)__tag_set((const void *)__addr, page_kasan_tag(__page));\
})
#define virt_to_page(x) ({ \
u64 __idx = (__tag_reset((u64)x) - PAGE_OFFSET) / PAGE_SIZE; \
u64 __addr = VMEMMAP_START + (__idx * sizeof(struct page)); \
(struct page *)__addr; \
u64 __addr = __tag_reset((u64)(x)) & PAGE_MASK; \
(struct page *)((s64)__addr >> VMEMMAP_SHIFT); \
})
#endif /* !CONFIG_SPARSEMEM_VMEMMAP || CONFIG_DEBUG_VIRTUAL */

2
arch/arm64/mm/init.c
View File

@ -502,6 +502,8 @@ static void __init free_unused_memmap(void)
*/
void __init mem_init(void)
{
BUILD_BUG_ON(!is_power_of_2(sizeof(struct page)));
if (swiotlb_force == SWIOTLB_FORCE ||
max_pfn > PFN_DOWN(arm64_dma_phys_limit ? : arm64_dma32_phys_limit))
swiotlb_init(1);