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Diffstat (limited to 'arch/sparc/mm/highmem.c')
| -rw-r--r-- | arch/sparc/mm/highmem.c | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/arch/sparc/mm/highmem.c b/arch/sparc/mm/highmem.c new file mode 100644 index 000000000..86bc2a58d --- /dev/null +++ b/arch/sparc/mm/highmem.c @@ -0,0 +1,133 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * highmem.c: virtual kernel memory mappings for high memory + * + * Provides kernel-static versions of atomic kmap functions originally + * found as inlines in include/asm-sparc/highmem.h. These became + * needed as kmap_atomic() and kunmap_atomic() started getting + * called from within modules. + * -- Tomas Szepe <szepe@pinerecords.com>, September 2002 + * + * But kmap_atomic() and kunmap_atomic() cannot be inlined in + * modules because they are loaded with btfixup-ped functions. + */ + +/* + * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap + * gives a more generic (and caching) interface. But kmap_atomic can + * be used in IRQ contexts, so in some (very limited) cases we need it. + * + * XXX This is an old text. Actually, it's good to use atomic kmaps, + * provided you remember that they are atomic and not try to sleep + * with a kmap taken, much like a spinlock. Non-atomic kmaps are + * shared by CPUs, and so precious, and establishing them requires IPI. + * Atomic kmaps are lightweight and we may have NCPUS more of them. + */ +#include <linux/highmem.h> +#include <linux/export.h> +#include <linux/mm.h> + +#include <asm/cacheflush.h> +#include <asm/tlbflush.h> +#include <asm/pgalloc.h> +#include <asm/vaddrs.h> + +pgprot_t kmap_prot; + +static pte_t *kmap_pte; + +void __init kmap_init(void) +{ + unsigned long address; + pmd_t *dir; + + address = __fix_to_virt(FIX_KMAP_BEGIN); + dir = pmd_offset(pgd_offset_k(address), address); + + /* cache the first kmap pte */ + kmap_pte = pte_offset_kernel(dir, address); + kmap_prot = __pgprot(SRMMU_ET_PTE | SRMMU_PRIV | SRMMU_CACHE); +} + +void *kmap_atomic(struct page *page) +{ + unsigned long vaddr; + long idx, type; + + preempt_disable(); + pagefault_disable(); + if (!PageHighMem(page)) + return page_address(page); + + type = kmap_atomic_idx_push(); + idx = type + KM_TYPE_NR*smp_processor_id(); + vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); + +/* XXX Fix - Anton */ +#if 0 + __flush_cache_one(vaddr); +#else + flush_cache_all(); +#endif + +#ifdef CONFIG_DEBUG_HIGHMEM + BUG_ON(!pte_none(*(kmap_pte-idx))); +#endif + set_pte(kmap_pte-idx, mk_pte(page, kmap_prot)); +/* XXX Fix - Anton */ +#if 0 + __flush_tlb_one(vaddr); +#else + flush_tlb_all(); +#endif + + return (void*) vaddr; +} +EXPORT_SYMBOL(kmap_atomic); + +void __kunmap_atomic(void *kvaddr) +{ + unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; + int type; + + if (vaddr < FIXADDR_START) { // FIXME + pagefault_enable(); + preempt_enable(); + return; + } + + type = kmap_atomic_idx(); + +#ifdef CONFIG_DEBUG_HIGHMEM + { + unsigned long idx; + + idx = type + KM_TYPE_NR * smp_processor_id(); + BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx)); + + /* XXX Fix - Anton */ +#if 0 + __flush_cache_one(vaddr); +#else + flush_cache_all(); +#endif + + /* + * force other mappings to Oops if they'll try to access + * this pte without first remap it + */ + pte_clear(&init_mm, vaddr, kmap_pte-idx); + /* XXX Fix - Anton */ +#if 0 + __flush_tlb_one(vaddr); +#else + flush_tlb_all(); +#endif + } +#endif + + kmap_atomic_idx_pop(); + pagefault_enable(); + preempt_enable(); +} +EXPORT_SYMBOL(__kunmap_atomic); |