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- // 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/vaddrs.h>
- static pte_t *kmap_pte;
- void __init kmap_init(void)
- {
- unsigned long address = __fix_to_virt(FIX_KMAP_BEGIN);
- /* cache the first kmap pte */
- kmap_pte = virt_to_kpte(address);
- }
- void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
- {
- unsigned long vaddr;
- long idx, type;
- 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, prot));
- /* XXX Fix - Anton */
- #if 0
- __flush_tlb_one(vaddr);
- #else
- flush_tlb_all();
- #endif
- return (void*) vaddr;
- }
- EXPORT_SYMBOL(kmap_atomic_high_prot);
- void kunmap_atomic_high(void *kvaddr)
- {
- unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
- int type;
- if (vaddr < FIXADDR_START)
- 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();
- }
- EXPORT_SYMBOL(kunmap_atomic_high);
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