ublk_drv: cleanup ublksrv_ctrl_dev_info

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

diff --git a/kernel/kcov.c b/kernel/kcov.c
index b3732b2..e19c84b 100644 (file)
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -204,8 +204,16 @@ void notrace __sanitizer_cov_trace_pc(void)
        /* The first 64-bit word is the number of subsequent PCs. */
        pos = READ_ONCE(area[0]) + 1;
        if (likely(pos < t->kcov_size)) {
-               area[pos] = ip;
+               /* Previously we write pc before updating pos. However, some
+                * early interrupt code could bypass check_kcov_mode() check
+                * and invoke __sanitizer_cov_trace_pc(). If such interrupt is
+                * raised between writing pc and updating pos, the pc could be
+                * overitten by the recursive __sanitizer_cov_trace_pc().
+                * Update pos before writing pc to avoid such interleaving.
+                */
                WRITE_ONCE(area[0], pos);
+               barrier();
+               area[pos] = ip;
        }
 }
 EXPORT_SYMBOL(__sanitizer_cov_trace_pc);
@@ -236,11 +244,13 @@ static void notrace write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip)
        start_index = 1 + count * KCOV_WORDS_PER_CMP;
        end_pos = (start_index + KCOV_WORDS_PER_CMP) * sizeof(u64);
        if (likely(end_pos <= max_pos)) {
+               /* See comment in __sanitizer_cov_trace_pc(). */
+               WRITE_ONCE(area[0], count + 1);
+               barrier();
                area[start_index] = type;
                area[start_index + 1] = arg1;
                area[start_index + 2] = arg2;
                area[start_index + 3] = ip;
-               WRITE_ONCE(area[0], count + 1);
        }
 }