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Message-ID: <alpine.LFD.2.02.1301291905510.6300@xanadu.home>
Date: Tue, 29 Jan 2013 19:06:35 -0500 (EST)
From: Nicolas Pitre <nicolas.pitre@...aro.org>
To: Joonsoo Kim <iamjoonsoo.kim@....com>
cc: Russell King <linux@....linux.org.uk>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
js1304@...il.com, Will Deacon <will.deacon@....com>,
Catalin Marinas <catalin.marinas@....com>
Subject: Re: [PATCH v3 3/3] ARM: mm: use static_vm for managing static mapped
areas
On Thu, 24 Jan 2013, Joonsoo Kim wrote:
> From: Joonsoo Kim <js1304@...il.com>
>
> A static mapped area is ARM-specific, so it is better not to use
> generic vmalloc data structure, that is, vmlist and vmlist_lock
> for managing static mapped area. And it causes some needless overhead and
> reducing this overhead is better idea.
>
> Now, we have newly introduced static_vm infrastructure.
> With it, we don't need to iterate all mapped areas. Instead, we just
> iterate static mapped areas. It helps to reduce an overhead of finding
> matched area. And architecture dependency on vmalloc layer is removed,
> so it will help to maintainability for vmalloc layer.
>
> Signed-off-by: Joonsoo Kim <js1304@...il.com>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
Given my comments to patch #2, the content of this patch should be
reworked accordingly.
>
> diff --git a/arch/arm/include/asm/mach/static_vm.h b/arch/arm/include/asm/mach/static_vm.h
> index 72c8339..24672b1 100644
> --- a/arch/arm/include/asm/mach/static_vm.h
> +++ b/arch/arm/include/asm/mach/static_vm.h
> @@ -32,6 +32,12 @@ struct static_vm {
> const void *caller;
> };
>
> +#define STATIC_VM_MEM 0x00000001
> +#define STATIC_VM_EMPTY 0x00000002
> +
> +/* mtype should be less than 28 */
> +#define STATIC_VM_MTYPE(mt) (1UL << ((mt) + 4))
> +
> extern struct static_vm *static_vmlist;
> extern spinlock_t static_vmlist_lock;
>
> diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
> index 88fd86c..2c0d3a1 100644
> --- a/arch/arm/mm/ioremap.c
> +++ b/arch/arm/mm/ioremap.c
> @@ -36,6 +36,7 @@
> #include <asm/system_info.h>
>
> #include <asm/mach/map.h>
> +#include <asm/mach/static_vm.h>
> #include <asm/mach/pci.h>
> #include "mm.h"
>
> @@ -197,7 +198,8 @@ void __iomem * __arm_ioremap_pfn_caller(unsigned long pfn,
> const struct mem_type *type;
> int err;
> unsigned long addr;
> - struct vm_struct * area;
> + struct vm_struct *area;
> + phys_addr_t paddr = __pfn_to_phys(pfn);
>
> #ifndef CONFIG_ARM_LPAE
> /*
> @@ -219,24 +221,17 @@ void __iomem * __arm_ioremap_pfn_caller(unsigned long pfn,
> /*
> * Try to reuse one of the static mapping whenever possible.
> */
> - read_lock(&vmlist_lock);
> - for (area = vmlist; area; area = area->next) {
> - if (!size || (sizeof(phys_addr_t) == 4 && pfn >= 0x100000))
> - break;
> - if (!(area->flags & VM_ARM_STATIC_MAPPING))
> - continue;
> - if ((area->flags & VM_ARM_MTYPE_MASK) != VM_ARM_MTYPE(mtype))
> - continue;
> - if (__phys_to_pfn(area->phys_addr) > pfn ||
> - __pfn_to_phys(pfn) + size-1 > area->phys_addr + area->size-1)
> - continue;
> - /* we can drop the lock here as we know *area is static */
> - read_unlock(&vmlist_lock);
> - addr = (unsigned long)area->addr;
> - addr += __pfn_to_phys(pfn) - area->phys_addr;
> - return (void __iomem *) (offset + addr);
> + if (size && !((sizeof(phys_addr_t) == 4 && pfn >= 0x100000))) {
> + struct static_vm *static_vm;
> +
> + static_vm = find_static_vm_paddr(__pfn_to_phys(pfn), size,
> + STATIC_VM_MEM | STATIC_VM_MTYPE(mtype));
> + if (static_vm) {
> + addr = (unsigned long)static_vm->vaddr;
> + addr += paddr - static_vm->paddr;
> + return (void __iomem *) (offset + addr);
> + }
> }
> - read_unlock(&vmlist_lock);
>
> /*
> * Don't allow RAM to be mapped - this causes problems with ARMv6+
> @@ -248,7 +243,7 @@ void __iomem * __arm_ioremap_pfn_caller(unsigned long pfn,
> if (!area)
> return NULL;
> addr = (unsigned long)area->addr;
> - area->phys_addr = __pfn_to_phys(pfn);
> + area->phys_addr = paddr;
>
> #if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
> if (DOMAIN_IO == 0 &&
> @@ -346,34 +341,20 @@ __arm_ioremap_exec(unsigned long phys_addr, size_t size, bool cached)
> void __iounmap(volatile void __iomem *io_addr)
> {
> void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);
> - struct vm_struct *vm;
> -
> - read_lock(&vmlist_lock);
> - for (vm = vmlist; vm; vm = vm->next) {
> - if (vm->addr > addr)
> - break;
> - if (!(vm->flags & VM_IOREMAP))
> - continue;
> - /* If this is a static mapping we must leave it alone */
> - if ((vm->flags & VM_ARM_STATIC_MAPPING) &&
> - (vm->addr <= addr) && (vm->addr + vm->size > addr)) {
> - read_unlock(&vmlist_lock);
> - return;
> - }
> + struct static_vm *static_vm;
> +
> + static_vm = find_static_vm_vaddr(addr);
> + if (static_vm)
> + return;
> +
> #if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE)
> - /*
> - * If this is a section based mapping we need to handle it
> - * specially as the VM subsystem does not know how to handle
> - * such a beast.
> - */
> - if ((vm->addr == addr) &&
> - (vm->flags & VM_ARM_SECTION_MAPPING)) {
> + {
> + struct vm_struct *vm;
> + vm = find_vm_area(addr);
> + if (vm && (vm->flags & VM_ARM_SECTION_MAPPING))
> unmap_area_sections((unsigned long)vm->addr, vm->size);
> - break;
> - }
> -#endif
> }
> - read_unlock(&vmlist_lock);
> +#endif
>
> vunmap(addr);
> }
> diff --git a/arch/arm/mm/mm.h b/arch/arm/mm/mm.h
> index a8ee92d..3ae75e5 100644
> --- a/arch/arm/mm/mm.h
> +++ b/arch/arm/mm/mm.h
> @@ -52,16 +52,6 @@ extern void __flush_dcache_page(struct address_space *mapping, struct page *page
> /* (super)section-mapped I/O regions used by ioremap()/iounmap() */
> #define VM_ARM_SECTION_MAPPING 0x80000000
>
> -/* permanent static mappings from iotable_init() */
> -#define VM_ARM_STATIC_MAPPING 0x40000000
> -
> -/* empty mapping */
> -#define VM_ARM_EMPTY_MAPPING 0x20000000
> -
> -/* mapping type (attributes) for permanent static mappings */
> -#define VM_ARM_MTYPE(mt) ((mt) << 20)
> -#define VM_ARM_MTYPE_MASK (0x1f << 20)
> -
> /* consistent regions used by dma_alloc_attrs() */
> #define VM_ARM_DMA_CONSISTENT 0x20000000
>
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index 9f06102..b799b69 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -31,6 +31,7 @@
>
> #include <asm/mach/arch.h>
> #include <asm/mach/map.h>
> +#include <asm/mach/static_vm.h>
> #include <asm/mach/pci.h>
>
> #include "mm.h"
> @@ -757,21 +758,28 @@ void __init iotable_init(struct map_desc *io_desc, int nr)
> {
> struct map_desc *md;
> struct vm_struct *vm;
> + struct static_vm *static_vm;
>
> if (!nr)
> return;
>
> vm = early_alloc_aligned(sizeof(*vm) * nr, __alignof__(*vm));
> + static_vm = early_alloc_aligned(sizeof(*static_vm) * nr,
> + __alignof__(*static_vm));
>
> for (md = io_desc; nr; md++, nr--) {
> create_mapping(md);
> +
> vm->addr = (void *)(md->virtual & PAGE_MASK);
> vm->size = PAGE_ALIGN(md->length + (md->virtual & ~PAGE_MASK));
> vm->phys_addr = __pfn_to_phys(md->pfn);
> - vm->flags = VM_IOREMAP | VM_ARM_STATIC_MAPPING;
> - vm->flags |= VM_ARM_MTYPE(md->type);
> + vm->flags = VM_IOREMAP;
> vm->caller = iotable_init;
> +
> + init_static_vm(static_vm, vm, STATIC_VM_MEM |
> + STATIC_VM_MTYPE(md->type));
> vm_area_add_early(vm++);
> + insert_static_vm(static_vm++);
> }
> }
>
> @@ -779,13 +787,20 @@ void __init vm_reserve_area_early(unsigned long addr, unsigned long size,
> void *caller)
> {
> struct vm_struct *vm;
> + struct static_vm *static_vm;
>
> vm = early_alloc_aligned(sizeof(*vm), __alignof__(*vm));
> + static_vm = early_alloc_aligned(sizeof(*static_vm),
> + __alignof__(*static_vm));
> +
> vm->addr = (void *)addr;
> vm->size = size;
> - vm->flags = VM_IOREMAP | VM_ARM_EMPTY_MAPPING;
> + vm->flags = VM_IOREMAP;
> vm->caller = caller;
> +
> + init_static_vm(static_vm, vm, STATIC_VM_EMPTY);
> vm_area_add_early(vm);
> + insert_static_vm(static_vm);
> }
>
> #ifndef CONFIG_ARM_LPAE
> @@ -810,15 +825,19 @@ static void __init pmd_empty_section_gap(unsigned long addr)
>
> static void __init fill_pmd_gaps(void)
> {
> - struct vm_struct *vm;
> + struct static_vm *area;
> unsigned long addr, next = 0;
> pmd_t *pmd;
>
> - /* we're still single threaded hence no lock needed here */
> - for (vm = vmlist; vm; vm = vm->next) {
> - if (!(vm->flags & (VM_ARM_STATIC_MAPPING | VM_ARM_EMPTY_MAPPING)))
> - continue;
> - addr = (unsigned long)vm->addr;
> + /*
> + * We should not take a lock here, because pmd_empty_section_gap()
> + * invokes vm_reserve_area_early(), and then it call insert_static_vm()
> + * which try to take a lock.
> + * We're still single thread, so traverse whole list without a lock
> + * is safe for now. And inserting new entry is also safe.
> + */
> + for (area = static_vmlist; area; area = area->next) {
> + addr = (unsigned long)area->vaddr;
> if (addr < next)
> continue;
>
> @@ -838,7 +857,7 @@ static void __init fill_pmd_gaps(void)
> * If so and the second section entry for this PMD is empty
> * then we block the corresponding virtual address.
> */
> - addr += vm->size;
> + addr += area->size;
> if ((addr & ~PMD_MASK) == SECTION_SIZE) {
> pmd = pmd_off_k(addr) + 1;
> if (pmd_none(*pmd))
> @@ -857,19 +876,12 @@ static void __init fill_pmd_gaps(void)
> #if defined(CONFIG_PCI) && !defined(CONFIG_NEED_MACH_IO_H)
> static void __init pci_reserve_io(void)
> {
> - struct vm_struct *vm;
> - unsigned long addr;
> + struct static_vm *static_vm;
>
> - /* we're still single threaded hence no lock needed here */
> - for (vm = vmlist; vm; vm = vm->next) {
> - if (!(vm->flags & VM_ARM_STATIC_MAPPING))
> - continue;
> - addr = (unsigned long)vm->addr;
> - addr &= ~(SZ_2M - 1);
> - if (addr == PCI_IO_VIRT_BASE)
> - return;
> + static_vm = find_static_vm_vaddr((void *)PCI_IO_VIRT_BASE);
> + if (static_vm)
> + return;
>
> - }
> vm_reserve_area_early(PCI_IO_VIRT_BASE, SZ_2M, pci_reserve_io);
> }
> #else
> --
> 1.7.9.5
>
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