Fixed MTP to work with TWRP

arch/sparc/mm/highmem.c

@@ -0,0 +1,130 @@
+/*
+ *  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;
+
+	/* 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);
+
+/* 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();
+		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();
+}
+EXPORT_SYMBOL(__kunmap_atomic);