coresight: trbe: Make sure we have enough space

mainline inclusion
from mainline-v5.15-rc3
commit adf35d05
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5YCYK
CVE: NA

Reference: https://lore.kernel.org/r/20211019163153.3692640-13-suzuki.poulose@arm.com

--------------------------------------------------------------------------

The TRBE driver makes sure that there is enough space for a meaningful
run, otherwise pads the given space and restarts the offset calculation
once. But there is no guarantee that we may find space or hit "no space".
Make sure that we repeat the step until, either :
  - We have the minimum space
   OR
  - There is NO space at all.

Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Reviewed-by: NAnshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: NSuzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20211019163153.3692640-13-suzuki.poulose@arm.comSigned-off-by: NMathieu Poirier <mathieu.poirier@linaro.org>

drivers/hwtracing/coresight/coresight-trbe.c

@@ -409,9 +409,10 @@ static unsigned long trbe_normal_offset(struct perf_output_handle *handle)
 	 * have space for a meaningful run, we rather pad it
 	 * and start fresh.
 	 */
-	if (limit && (limit - head < TRBE_TRACE_MIN_BUF_SIZE)) {
+	while (limit && (limit - head < TRBE_TRACE_MIN_BUF_SIZE)) {
 		trbe_pad_buf(handle, limit - head);
 		limit = __trbe_normal_offset(handle);
+		head = PERF_IDX2OFF(handle->head, buf);
 	}
 	return limit;
 }