Merge tag 'for-4.18-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave...

[linux-2.6-microblaze.git] / kernel / kcov.c

diff --git a/kernel/kcov.c b/kernel/kcov.c
index 2c16f1a..3ebd09e 100644 (file)
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -58,7 +58,7 @@ struct kcov {
 
 static bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t)
 {
-       enum kcov_mode mode;
+       unsigned int mode;
 
        /*
         * We are interested in code coverage as a function of a syscall inputs,
@@ -241,7 +241,8 @@ static void kcov_put(struct kcov *kcov)
 
 void kcov_task_init(struct task_struct *t)
 {
-       t->kcov_mode = KCOV_MODE_DISABLED;
+       WRITE_ONCE(t->kcov_mode, KCOV_MODE_DISABLED);
+       barrier();
        t->kcov_size = 0;
        t->kcov_area = NULL;
        t->kcov = NULL;
@@ -323,6 +324,21 @@ static int kcov_close(struct inode *inode, struct file *filep)
        return 0;
 }
 
+/*
+ * Fault in a lazily-faulted vmalloc area before it can be used by
+ * __santizer_cov_trace_pc(), to avoid recursion issues if any code on the
+ * vmalloc fault handling path is instrumented.
+ */
+static void kcov_fault_in_area(struct kcov *kcov)
+{
+       unsigned long stride = PAGE_SIZE / sizeof(unsigned long);
+       unsigned long *area = kcov->area;
+       unsigned long offset;
+
+       for (offset = 0; offset < kcov->size; offset += stride)
+               READ_ONCE(area[offset]);
+}
+
 static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd,
                             unsigned long arg)
 {
@@ -371,6 +387,7 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd,
 #endif
                else
                        return -EINVAL;
+               kcov_fault_in_area(kcov);
                /* Cache in task struct for performance. */
                t->kcov_size = kcov->size;
                t->kcov_area = kcov->area;