x86 mmiotrace: fix page-unaligned ioremaps

mmiotrace_ioremap() expects to receive the original unaligned map phys address
and size. Also fix {un,}register_kmmio_probe() to deal properly with
unaligned size.
Signed-off-by: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/mm/ioremap.c

@@ -123,6 +123,8 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
 {
 	unsigned long pfn, offset, vaddr;
 	resource_size_t last_addr;
+	const resource_size_t unaligned_phys_addr = phys_addr;
+	const unsigned long unaligned_size = size;
 	struct vm_struct *area;
 	unsigned long new_prot_val;
 	pgprot_t prot;
@@ -236,7 +238,7 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
 	}
 
 	ret_addr = (void __iomem *) (vaddr + offset);
-	mmiotrace_ioremap(phys_addr, size, ret_addr);
+	mmiotrace_ioremap(unaligned_phys_addr, unaligned_size, ret_addr);
 
 	return ret_addr;
 }

arch/x86/mm/kmmio.c

@@ -351,11 +351,19 @@ static void release_kmmio_fault_page(unsigned long page,
 	}
 }
 
+/*
+ * With page-unaligned ioremaps, one or two armed pages may contain
+ * addresses from outside the intended mapping. Events for these addresses
+ * are currently silently dropped. The events may result only from programming
+ * mistakes by accessing addresses before the beginning or past the end of a
+ * mapping.
+ */
 int register_kmmio_probe(struct kmmio_probe *p)
 {
 	unsigned long flags;
 	int ret = 0;
 	unsigned long size = 0;
+	const unsigned long size_lim = p->len + (p->addr & ~PAGE_MASK);
 
 	spin_lock_irqsave(&kmmio_lock, flags);
 	if (get_kmmio_probe(p->addr)) {
@@ -364,7 +372,7 @@ int register_kmmio_probe(struct kmmio_probe *p)
 	}
 	kmmio_count++;
 	list_add_rcu(&p->list, &kmmio_probes);
-	while (size < p->len) {
+	while (size < size_lim) {
 		if (add_kmmio_fault_page(p->addr + size))
 			pr_err("kmmio: Unable to set page fault.\n");
 		size += PAGE_SIZE;
@@ -436,11 +444,12 @@ void unregister_kmmio_probe(struct kmmio_probe *p)
 {
 	unsigned long flags;
 	unsigned long size = 0;
+	const unsigned long size_lim = p->len + (p->addr & ~PAGE_MASK);
 	struct kmmio_fault_page *release_list = NULL;
 	struct kmmio_delayed_release *drelease;
 
 	spin_lock_irqsave(&kmmio_lock, flags);
-	while (size < p->len) {
+	while (size < size_lim) {
 		release_kmmio_fault_page(p->addr + size, &release_list);
 		size += PAGE_SIZE;
 	}

arch/x86/mm/mmio-mod.c

@@ -280,6 +280,7 @@ static void ioremap_trace_core(unsigned long offset, unsigned long size,
 {
 	static atomic_t next_id;
 	struct remap_trace *trace = kmalloc(sizeof(*trace), GFP_KERNEL);
+	/* These are page-unaligned. */
 	struct mmiotrace_map map = {
 		.phys = offset,
 		.virt = (unsigned long)addr,