--- /dev/null
+/*
+ * 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
--- /dev/null
+/*
+ * 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);
+}
projects / mirror_ubuntu-eoan-kernel.git / commitdiff