diff options
Diffstat (limited to 'kernel/kcov.c')
| -rw-r--r-- | kernel/kcov.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/kcov.c b/kernel/kcov.c index 1d85597057e1..6563141f5de9 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -978,6 +978,15 @@ static void kcov_move_area(enum kcov_mode mode, void *dst_area, memcpy(dst_entries, src_entries, bytes_to_move); entries_moved = bytes_to_move >> entry_size_log; + /* + * A write memory barrier is required here, to ensure + * that the writes from the memcpy() are visible before + * the count is updated. Without this, it is possible for + * a user to observe a new count value but stale + * coverage data. + */ + smp_wmb(); + switch (mode) { case KCOV_MODE_TRACE_PC: WRITE_ONCE(*(unsigned long *)dst_area, dst_len + entries_moved); |