From 3e1907d5bf5a1e0b182ee599f92586f0165029e2 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Wed, 30 Mar 2016 16:46:00 +0200 Subject: 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 Signed-off-by: Will Deacon --- arch/arm64/include/asm/memory.h | 18 +++++++++++++++++- arch/arm64/include/asm/pgtable.h | 11 +++-------- arch/arm64/mm/dump.c | 16 ++++++++-------- arch/arm64/mm/init.c | 14 ++++++++++---- 4 files changed, 38 insertions(+), 21 deletions(-) (limited to 'arch') diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index 12f8a00fb3f1..8a2ab195ca77 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -39,6 +39,21 @@ */ #define PCI_IO_SIZE SZ_16M +/* + * Log2 of the upper bound of the size of a struct page. Used for sizing + * the vmemmap region only, does not affect actual memory footprint. + * We don't use sizeof(struct page) directly since taking its size here + * requires its definition to be available at this point in the inclusion + * chain, and it may not be a power of 2 in the first place. + */ +#define STRUCT_PAGE_MAX_SHIFT 6 + +/* + * VMEMMAP_SIZE - allows the whole linear region to be covered by + * a struct page array + */ +#define VMEMMAP_SIZE (UL(1) << (VA_BITS - PAGE_SHIFT - 1 + STRUCT_PAGE_MAX_SHIFT)) + /* * PAGE_OFFSET - the virtual address of the start of the kernel image (top * (VA_BITS - 1)) @@ -54,7 +69,8 @@ #define MODULES_END (MODULES_VADDR + MODULES_VSIZE) #define MODULES_VADDR (VA_START + KASAN_SHADOW_SIZE) #define MODULES_VSIZE (SZ_128M) -#define PCI_IO_END (PAGE_OFFSET - SZ_2M) +#define VMEMMAP_START (PAGE_OFFSET - VMEMMAP_SIZE) +#define PCI_IO_END (VMEMMAP_START - SZ_2M) #define PCI_IO_START (PCI_IO_END - PCI_IO_SIZE) #define FIXADDR_TOP (PCI_IO_START - SZ_2M) #define TASK_SIZE_64 (UL(1) << VA_BITS) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 377257a8d393..2abfa4d09e65 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -24,20 +24,15 @@ #include /* - * VMALLOC and SPARSEMEM_VMEMMAP ranges. + * VMALLOC range. * - * VMEMAP_SIZE: allows the whole linear region to be covered by a struct page array - * (rounded up to PUD_SIZE). * VMALLOC_START: beginning of the kernel vmalloc space - * VMALLOC_END: extends to the available space below vmmemmap, PCI I/O space, - * fixed mappings and modules + * VMALLOC_END: extends to the available space below vmmemmap, PCI I/O space + * and fixed mappings */ -#define VMEMMAP_SIZE ALIGN((1UL << (VA_BITS - PAGE_SHIFT - 1)) * sizeof(struct page), PUD_SIZE) - #define VMALLOC_START (MODULES_END) #define VMALLOC_END (PAGE_OFFSET - PUD_SIZE - VMEMMAP_SIZE - SZ_64K) -#define VMEMMAP_START (VMALLOC_END + SZ_64K) #define vmemmap ((struct page *)VMEMMAP_START - (memstart_addr >> PAGE_SHIFT)) #define FIRST_USER_ADDRESS 0UL diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c index f9271cb2f5e3..a21f47421b0c 100644 --- a/arch/arm64/mm/dump.c +++ b/arch/arm64/mm/dump.c @@ -37,14 +37,14 @@ enum address_markers_idx { MODULES_END_NR, VMALLOC_START_NR, VMALLOC_END_NR, -#ifdef CONFIG_SPARSEMEM_VMEMMAP - VMEMMAP_START_NR, - VMEMMAP_END_NR, -#endif FIXADDR_START_NR, FIXADDR_END_NR, PCI_START_NR, PCI_END_NR, +#ifdef CONFIG_SPARSEMEM_VMEMMAP + VMEMMAP_START_NR, + VMEMMAP_END_NR, +#endif KERNEL_SPACE_NR, }; @@ -53,14 +53,14 @@ static struct addr_marker address_markers[] = { { MODULES_END, "Modules end" }, { VMALLOC_START, "vmalloc() Area" }, { VMALLOC_END, "vmalloc() End" }, -#ifdef CONFIG_SPARSEMEM_VMEMMAP - { 0, "vmemmap start" }, - { 0, "vmemmap end" }, -#endif { FIXADDR_START, "Fixmap start" }, { FIXADDR_TOP, "Fixmap end" }, { PCI_IO_START, "PCI I/O start" }, { PCI_IO_END, "PCI I/O end" }, +#ifdef CONFIG_SPARSEMEM_VMEMMAP + { 0, "vmemmap start" }, + { 0, "vmemmap end" }, +#endif { PAGE_OFFSET, "Linear Mapping" }, { -1, NULL }, }; diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 89376f3c65a3..d55d720dba79 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -412,6 +412,10 @@ void __init mem_init(void) MLK_ROUNDUP(__start_rodata, _etext), MLK_ROUNDUP(__init_begin, __init_end), MLK_ROUNDUP(_sdata, _edata)); + pr_cont(" fixed : 0x%16lx - 0x%16lx (%6ld KB)\n", + MLK(FIXADDR_START, FIXADDR_TOP)); + pr_cont(" PCI I/O : 0x%16lx - 0x%16lx (%6ld MB)\n", + MLM(PCI_IO_START, PCI_IO_END)); #ifdef CONFIG_SPARSEMEM_VMEMMAP pr_cont(" vmemmap : 0x%16lx - 0x%16lx (%6ld GB maximum)\n" " 0x%16lx - 0x%16lx (%6ld MB actual)\n", @@ -420,10 +424,6 @@ void __init mem_init(void) MLM((unsigned long)phys_to_page(memblock_start_of_DRAM()), (unsigned long)virt_to_page(high_memory))); #endif - pr_cont(" fixed : 0x%16lx - 0x%16lx (%6ld KB)\n", - MLK(FIXADDR_START, FIXADDR_TOP)); - pr_cont(" PCI I/O : 0x%16lx - 0x%16lx (%6ld MB)\n", - MLM(PCI_IO_START, PCI_IO_END)); pr_cont(" memory : 0x%16lx - 0x%16lx (%6ld MB)\n", MLM(__phys_to_virt(memblock_start_of_DRAM()), (unsigned long)high_memory)); @@ -440,6 +440,12 @@ void __init mem_init(void) BUILD_BUG_ON(TASK_SIZE_32 > TASK_SIZE_64); #endif + /* + * Make sure we chose the upper bound of sizeof(struct page) + * correctly. + */ + BUILD_BUG_ON(sizeof(struct page) > (1 << STRUCT_PAGE_MAX_SHIFT)); + if (PAGE_SIZE >= 16384 && get_num_physpages() <= 128) { extern int sysctl_overcommit_memory; /* -- cgit v1.2.3-59-g8ed1b