perf, pt, coresight: Fix address filters for vmas with non-zero offset

Currently, the address range calculation for file-based filters works as
long as the vma that maps the matching part of the object file starts
from offset zero into the file (vm_pgoff==0). Otherwise, the resulting
filter range would be off by vm_pgoff pages. Another related problem is
that in case of a partially matching vma, that is, a vma that matches
part of a filter region, the filter range size wouldn't be adjusted.

Fix the arithmetics around address filter range calculations, taking
into account vma offset, so that the entire calculation is done before
the filter configuration is passed to the PMU drivers instead of having
those drivers do the final bit of arithmetics.

Based on the patch by Adrian Hunter <adrian.hunter.intel.com>.

Reported-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Fixes: 375637bc5249 ("perf/core: Introduce address range filtering")
Link: http://lkml.kernel.org/r/20190215115655.63469-3-alexander.shishkin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 47 insertions, 34 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 2d89efc0a3e0..16609f6737da 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2799,7 +2799,7 @@ static int perf_event_stop(struct perf_event *event, int restart)
  *
  * (p1) when userspace mappings change as a result of (1) or (2) or (3) below,
  *      we update the addresses of corresponding vmas in
- *	event::addr_filters_offs array and bump the event::addr_filters_gen;
+ *	event::addr_filter_ranges array and bump the event::addr_filters_gen;
  * (p2) when an event is scheduled in (pmu::add), it calls
  *      perf_event_addr_filters_sync() which calls pmu::addr_filters_sync()
  *      if the generation has changed since the previous call.
@@ -4446,7 +4446,7 @@ static void _free_event(struct perf_event *event)
 
 	perf_event_free_bpf_prog(event);
 	perf_addr_filters_splice(event, NULL);
-	kfree(event->addr_filters_offs);
+	kfree(event->addr_filter_ranges);
 
 	if (event->destroy)
 		event->destroy(event);
@@ -6687,7 +6687,8 @@ static void perf_event_addr_filters_exec(struct perf_event *event, void *data)
 	raw_spin_lock_irqsave(&ifh->lock, flags);
 	list_for_each_entry(filter, &ifh->list, entry) {
 		if (filter->path.dentry) {
-			event->addr_filters_offs[count] = 0;
+			event->addr_filter_ranges[count].start = 0;
+			event->addr_filter_ranges[count].size = 0;
 			restart++;
 		}
 
@@ -7367,28 +7368,47 @@ static bool perf_addr_filter_match(struct perf_addr_filter *filter,
 	return true;
 }
 
+static bool perf_addr_filter_vma_adjust(struct perf_addr_filter *filter,
+					struct vm_area_struct *vma,
+					struct perf_addr_filter_range *fr)
+{
+	unsigned long vma_size = vma->vm_end - vma->vm_start;
+	unsigned long off = vma->vm_pgoff << PAGE_SHIFT;
+	struct file *file = vma->vm_file;
+
+	if (!perf_addr_filter_match(filter, file, off, vma_size))
+		return false;
+
+	if (filter->offset < off) {
+		fr->start = vma->vm_start;
+		fr->size = min(vma_size, filter->size - (off - filter->offset));
+	} else {
+		fr->start = vma->vm_start + filter->offset - off;
+		fr->size = min(vma->vm_end - fr->start, filter->size);
+	}
+
+	return true;
+}
+
 static void __perf_addr_filters_adjust(struct perf_event *event, void *data)
 {
 	struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
 	struct vm_area_struct *vma = data;
-	unsigned long off = vma->vm_pgoff << PAGE_SHIFT, flags;
-	struct file *file = vma->vm_file;
 	struct perf_addr_filter *filter;
 	unsigned int restart = 0, count = 0;
+	unsigned long flags;
 
 	if (!has_addr_filter(event))
 		return;
 
-	if (!file)
+	if (!vma->vm_file)
 		return;
 
 	raw_spin_lock_irqsave(&ifh->lock, flags);
 	list_for_each_entry(filter, &ifh->list, entry) {
-		if (perf_addr_filter_match(filter, file, off,
-					     vma->vm_end - vma->vm_start)) {
-			event->addr_filters_offs[count] = vma->vm_start;
+		if (perf_addr_filter_vma_adjust(filter, vma,
+						&event->addr_filter_ranges[count]))
 			restart++;
-		}
 
 		count++;
 	}
@@ -8978,26 +8998,19 @@ static void perf_addr_filters_splice(struct perf_event *event,
  * @filter; if so, adjust filter's address range.
  * Called with mm::mmap_sem down for reading.
  */
-static unsigned long perf_addr_filter_apply(struct perf_addr_filter *filter,
-					    struct mm_struct *mm)
+static void perf_addr_filter_apply(struct perf_addr_filter *filter,
+				   struct mm_struct *mm,
+				   struct perf_addr_filter_range *fr)
 {
 	struct vm_area_struct *vma;
 
 	for (vma = mm->mmap; vma; vma = vma->vm_next) {
-		struct file *file = vma->vm_file;
-		unsigned long off = vma->vm_pgoff << PAGE_SHIFT;
-		unsigned long vma_size = vma->vm_end - vma->vm_start;
-
-		if (!file)
+		if (!vma->vm_file)
 			continue;
 
-		if (!perf_addr_filter_match(filter, file, off, vma_size))
-			continue;
-
-		return vma->vm_start;
+		if (perf_addr_filter_vma_adjust(filter, vma, fr))
+			return;
 	}
-
-	return 0;
 }
 
 /*
@@ -9031,15 +9044,15 @@ static void perf_event_addr_filters_apply(struct perf_event *event)
 
 	raw_spin_lock_irqsave(&ifh->lock, flags);
 	list_for_each_entry(filter, &ifh->list, entry) {
-		event->addr_filters_offs[count] = 0;
+		event->addr_filter_ranges[count].start = 0;
+		event->addr_filter_ranges[count].size = 0;
 
 		/*
 		 * Adjust base offset if the filter is associated to a binary
 		 * that needs to be mapped:
 		 */
 		if (filter->path.dentry)
-			event->addr_filters_offs[count] =
-				perf_addr_filter_apply(filter, mm);
+			perf_addr_filter_apply(filter, mm, &event->addr_filter_ranges[count]);
 
 		count++;
 	}
@@ -10305,10 +10318,10 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 		goto err_pmu;
 
 	if (has_addr_filter(event)) {
-		event->addr_filters_offs = kcalloc(pmu->nr_addr_filters,
-						   sizeof(unsigned long),
-						   GFP_KERNEL);
-		if (!event->addr_filters_offs) {
+		event->addr_filter_ranges = kcalloc(pmu->nr_addr_filters,
+						    sizeof(struct perf_addr_filter_range),
+						    GFP_KERNEL);
+		if (!event->addr_filter_ranges) {
 			err = -ENOMEM;
 			goto err_per_task;
 		}
@@ -10321,9 +10334,9 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 			struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
 
 			raw_spin_lock_irq(&ifh->lock);
-			memcpy(event->addr_filters_offs,
-			       event->parent->addr_filters_offs,
-			       pmu->nr_addr_filters * sizeof(unsigned long));
+			memcpy(event->addr_filter_ranges,
+			       event->parent->addr_filter_ranges,
+			       pmu->nr_addr_filters * sizeof(struct perf_addr_filter_range));
 			raw_spin_unlock_irq(&ifh->lock);
 		}
 
@@ -10345,7 +10358,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 	return event;
 
 err_addr_filters:
-	kfree(event->addr_filters_offs);
+	kfree(event->addr_filter_ranges);
 
 err_per_task:
 	exclusive_event_destroy(event);