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>

1 files changed, 11 insertions, 2 deletions

diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c
index 6a92d9111b64..93b1797666cb 100644
--- a/arch/x86/mm/kmmio.c
+++ b/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;
         }