diff options
| -rw-r--r-- | arch/arc/Kconfig | 7 | ||||
| -rw-r--r-- | arch/arc/include/asm/highmem.h | 61 | ||||
| -rw-r--r-- | arch/arc/include/asm/kmap_types.h | 18 | ||||
| -rw-r--r-- | arch/arc/include/asm/processor.h | 7 | ||||
| -rw-r--r-- | arch/arc/mm/Makefile | 1 | ||||
| -rw-r--r-- | arch/arc/mm/highmem.c | 140 |
6 files changed, 233 insertions, 1 deletions
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig index cc938967282b..fd9632f4ddc8 100644 --- a/arch/arc/Kconfig +++ b/arch/arc/Kconfig @@ -446,6 +446,13 @@ config LINUX_LINK_BASE Linux needs to be scooted a bit. If you don't know what the above means, leave this setting alone. +config HIGHMEM + bool "High Memory Support" + help + With ARC 2G:2G address split, only upper 2G is directly addressable by + kernel. Enable this to potentially allow access to rest of 2G and PAE + in future + config ARC_CURR_IN_REG bool "Dedicate Register r25 for current_task pointer" default y diff --git a/arch/arc/include/asm/highmem.h b/arch/arc/include/asm/highmem.h new file mode 100644 index 000000000000..b1585c96324a --- /dev/null +++ b/arch/arc/include/asm/highmem.h @@ -0,0 +1,61 @@ +/* + * Copyright (C) 2015 Synopsys, Inc. (www.synopsys.com) + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#ifndef _ASM_HIGHMEM_H +#define _ASM_HIGHMEM_H + +#ifdef CONFIG_HIGHMEM + +#include <uapi/asm/page.h> +#include <asm/kmap_types.h> + +/* start after vmalloc area */ +#define FIXMAP_BASE (PAGE_OFFSET - FIXMAP_SIZE - PKMAP_SIZE) +#define FIXMAP_SIZE PGDIR_SIZE /* only 1 PGD worth */ +#define KM_TYPE_NR ((FIXMAP_SIZE >> PAGE_SHIFT)/NR_CPUS) +#define FIXMAP_ADDR(nr) (FIXMAP_BASE + ((nr) << PAGE_SHIFT)) + +/* start after fixmap area */ +#define PKMAP_BASE (FIXMAP_BASE + FIXMAP_SIZE) +#define PKMAP_SIZE PGDIR_SIZE +#define LAST_PKMAP (PKMAP_SIZE >> PAGE_SHIFT) +#define LAST_PKMAP_MASK (LAST_PKMAP - 1) +#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT)) +#define PKMAP_NR(virt) (((virt) - PKMAP_BASE) >> PAGE_SHIFT) + +#define kmap_prot PAGE_KERNEL + + +#include <asm/cacheflush.h> + +extern void *kmap(struct page *page); +extern void *kmap_high(struct page *page); +extern void *kmap_atomic(struct page *page); +extern void __kunmap_atomic(void *kvaddr); +extern void kunmap_high(struct page *page); + +extern void kmap_init(void); + +static inline void flush_cache_kmaps(void) +{ + flush_cache_all(); +} + +static inline void kunmap(struct page *page) +{ + BUG_ON(in_interrupt()); + if (!PageHighMem(page)) + return; + kunmap_high(page); +} + + +#endif + +#endif diff --git a/arch/arc/include/asm/kmap_types.h b/arch/arc/include/asm/kmap_types.h new file mode 100644 index 000000000000..f0d7f6acea4e --- /dev/null +++ b/arch/arc/include/asm/kmap_types.h @@ -0,0 +1,18 @@ +/* + * Copyright (C) 2015 Synopsys, Inc. (www.synopsys.com) + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#ifndef _ASM_KMAP_TYPES_H +#define _ASM_KMAP_TYPES_H + +/* + * We primarily need to define KM_TYPE_NR here but that in turn + * is a function of PGDIR_SIZE etc. + * To avoid circular deps issue, put everything in asm/highmem.h + */ +#endif diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h index ee682d8e0213..44545354e9e8 100644 --- a/arch/arc/include/asm/processor.h +++ b/arch/arc/include/asm/processor.h @@ -114,7 +114,12 @@ extern unsigned int get_wchan(struct task_struct *p); * ----------------------------------------------------------------------------- */ #define VMALLOC_START 0x70000000 -#define VMALLOC_SIZE (PAGE_OFFSET - VMALLOC_START) + +/* + * 1 PGDIR_SIZE each for fixmap/pkmap, 2 PGDIR_SIZE gutter + * See asm/highmem.h for details + */ +#define VMALLOC_SIZE (PAGE_OFFSET - VMALLOC_START - PGDIR_SIZE * 4) #define VMALLOC_END (VMALLOC_START + VMALLOC_SIZE) #define USER_KERNEL_GUTTER 0x10000000 diff --git a/arch/arc/mm/Makefile b/arch/arc/mm/Makefile index 7beb941556c3..3703a4969349 100644 --- a/arch/arc/mm/Makefile +++ b/arch/arc/mm/Makefile @@ -8,3 +8,4 @@ obj-y := extable.o ioremap.o dma.o fault.o init.o obj-y += tlb.o tlbex.o cache.o mmap.o +obj-$(CONFIG_HIGHMEM) += highmem.o diff --git a/arch/arc/mm/highmem.c b/arch/arc/mm/highmem.c new file mode 100644 index 000000000000..065ee6bfa82a --- /dev/null +++ b/arch/arc/mm/highmem.c @@ -0,0 +1,140 @@ +/* + * Copyright (C) 2015 Synopsys, Inc. (www.synopsys.com) + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#include <linux/bootmem.h> +#include <linux/export.h> +#include <linux/highmem.h> +#include <asm/processor.h> +#include <asm/pgtable.h> +#include <asm/pgalloc.h> +#include <asm/tlbflush.h> + +/* + * HIGHMEM API: + * + * kmap() API provides sleep semantics hence refered to as "permanent maps" + * It allows mapping LAST_PKMAP pages, using @last_pkmap_nr as the cursor + * for book-keeping + * + * kmap_atomic() can't sleep (calls pagefault_disable()), thus it provides + * shortlived ala "temporary mappings" which historically were implemented as + * fixmaps (compile time addr etc). Their book-keeping is done per cpu. + * + * Both these facts combined (preemption disabled and per-cpu allocation) + * means the total number of concurrent fixmaps will be limited to max + * such allocations in a single control path. Thus KM_TYPE_NR (another + * historic relic) is a small'ish number which caps max percpu fixmaps + * + * ARC HIGHMEM Details + * + * - the kernel vaddr space from 0x7z to 0x8z (currently used by vmalloc/module) + * is now shared between vmalloc and kmap (non overlapping though) + * + * - Both fixmap/pkmap use a dedicated page table each, hooked up to swapper PGD + * This means each only has 1 PGDIR_SIZE worth of kvaddr mappings, which means + * 2M of kvaddr space for typical config (8K page and 11:8:13 traversal split) + * + * - fixmap anyhow needs a limited number of mappings. So 2M kvaddr == 256 PTE + * slots across NR_CPUS would be more than sufficient (generic code defines + * KM_TYPE_NR as 20). + * + * - pkmap being preemptible, in theory could do with more than 256 concurrent + * mappings. However, generic pkmap code: map_new_virtual(), doesn't traverse + * the PGD and only works with a single page table @pkmap_page_table, hence + * sets the limit + */ + +extern pte_t * pkmap_page_table; +static pte_t * fixmap_page_table; + +void *kmap(struct page *page) +{ + BUG_ON(in_interrupt()); + if (!PageHighMem(page)) + return page_address(page); + + return kmap_high(page); +} + +void *kmap_atomic(struct page *page) +{ + int idx, cpu_idx; + unsigned long vaddr; + + preempt_disable(); + pagefault_disable(); + if (!PageHighMem(page)) + return page_address(page); + + cpu_idx = kmap_atomic_idx_push(); + idx = cpu_idx + KM_TYPE_NR * smp_processor_id(); + vaddr = FIXMAP_ADDR(idx); + + set_pte_at(&init_mm, vaddr, fixmap_page_table + idx, + mk_pte(page, kmap_prot)); + + return (void *)vaddr; +} +EXPORT_SYMBOL(kmap_atomic); + +void __kunmap_atomic(void *kv) +{ + unsigned long kvaddr = (unsigned long)kv; + + if (kvaddr >= FIXMAP_BASE && kvaddr < (FIXMAP_BASE + FIXMAP_SIZE)) { + + /* + * Because preemption is disabled, this vaddr can be associated + * with the current allocated index. + * But in case of multiple live kmap_atomic(), it still relies on + * callers to unmap in right order. + */ + int cpu_idx = kmap_atomic_idx(); + int idx = cpu_idx + KM_TYPE_NR * smp_processor_id(); + + WARN_ON(kvaddr != FIXMAP_ADDR(idx)); + + pte_clear(&init_mm, kvaddr, fixmap_page_table + idx); + local_flush_tlb_kernel_range(kvaddr, kvaddr + PAGE_SIZE); + + kmap_atomic_idx_pop(); + } + + pagefault_enable(); + preempt_enable(); +} +EXPORT_SYMBOL(__kunmap_atomic); + +noinline pte_t *alloc_kmap_pgtable(unsigned long kvaddr) +{ + pgd_t *pgd_k; + pud_t *pud_k; + pmd_t *pmd_k; + pte_t *pte_k; + + pgd_k = pgd_offset_k(kvaddr); + pud_k = pud_offset(pgd_k, kvaddr); + pmd_k = pmd_offset(pud_k, kvaddr); + + pte_k = (pte_t *)alloc_bootmem_low_pages(PAGE_SIZE); + pmd_populate_kernel(&init_mm, pmd_k, pte_k); + return pte_k; +} + +void kmap_init(void) +{ + /* Due to recursive include hell, we can't do this in processor.h */ + BUILD_BUG_ON(PAGE_OFFSET < (VMALLOC_END + FIXMAP_SIZE + PKMAP_SIZE)); + + BUILD_BUG_ON(KM_TYPE_NR > PTRS_PER_PTE); + pkmap_page_table = alloc_kmap_pgtable(PKMAP_BASE); + + BUILD_BUG_ON(LAST_PKMAP > PTRS_PER_PTE); + fixmap_page_table = alloc_kmap_pgtable(FIXMAP_BASE); +} |