summaryrefslogtreecommitdiff
path: root/arch/powerpc/mm/highmem.c
diff options
context:
space:
mode:
authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/powerpc/mm/highmem.c
Initial import
Diffstat (limited to 'arch/powerpc/mm/highmem.c')
-rw-r--r--arch/powerpc/mm/highmem.c86
1 files changed, 86 insertions, 0 deletions
diff --git a/arch/powerpc/mm/highmem.c b/arch/powerpc/mm/highmem.c
new file mode 100644
index 000000000..e7450bdbe
--- /dev/null
+++ b/arch/powerpc/mm/highmem.c
@@ -0,0 +1,86 @@
+/*
+ * highmem.c: virtual kernel memory mappings for high memory
+ *
+ * PowerPC version, stolen from the i386 version.
+ *
+ * Used in CONFIG_HIGHMEM systems for memory pages which
+ * are not addressable by direct kernel virtual addresses.
+ *
+ * Copyright (C) 1999 Gerhard Wichert, Siemens AG
+ * Gerhard.Wichert@pdb.siemens.de
+ *
+ *
+ * Redesigned the x86 32-bit VM architecture to deal with
+ * up to 16 Terrabyte physical memory. With current x86 CPUs
+ * we now support up to 64 Gigabytes physical RAM.
+ *
+ * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
+ *
+ * Reworked for PowerPC by various contributors. Moved from
+ * highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp.
+ */
+
+#include <linux/highmem.h>
+#include <linux/module.h>
+
+/*
+ * 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.
+ */
+void *kmap_atomic_prot(struct page *page, pgprot_t prot)
+{
+ unsigned long vaddr;
+ int idx, type;
+
+ /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
+ 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);
+#ifdef CONFIG_DEBUG_HIGHMEM
+ BUG_ON(!pte_none(*(kmap_pte-idx)));
+#endif
+ __set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot), 1);
+ local_flush_tlb_page(NULL, vaddr);
+
+ return (void*) vaddr;
+}
+EXPORT_SYMBOL(kmap_atomic_prot);
+
+void __kunmap_atomic(void *kvaddr)
+{
+ unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
+ int type;
+
+ if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
+ pagefault_enable();
+ return;
+ }
+
+ type = kmap_atomic_idx();
+
+#ifdef CONFIG_DEBUG_HIGHMEM
+ {
+ unsigned int idx;
+
+ idx = type + KM_TYPE_NR * smp_processor_id();
+ BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
+
+ /*
+ * 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);
+ local_flush_tlb_page(NULL, vaddr);
+ }
+#endif
+
+ kmap_atomic_idx_pop();
+ pagefault_enable();
+}
+EXPORT_SYMBOL(__kunmap_atomic);