[PATCH 13/24] trace: Correct the relocation handover with buffer overflow

[Simon Glass]

When the early trace buffer overflows it leaves a gap in the trace buffer
between where the actual data finished and where it would have finished if
there were enough buffer space. This results in corrupted output.

Adjust the logic to resolve this and add a message when the buffer
overflows.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

 lib/trace.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/lib/trace.c b/lib/trace.c
index c3354a256fb..bbc316af295 100644
--- a/lib/trace.c
+++ b/lib/trace.c
@@ -360,8 +360,8 @@ int notrace trace_init(void *buff, size_t buff_size)
 
 	if (!was_disabled) {
 #ifdef CONFIG_TRACE_EARLY
+		ulong used, count;
 		char *end;
-		ulong used;
 
 		/*
 		 * Copy over the early trace data if we have it. Disable
@@ -370,12 +370,19 @@ int notrace trace_init(void *buff, size_t buff_size)
 		trace_enabled = 0;
 		hdr = map_sysmem(CONFIG_TRACE_EARLY_ADDR,
 				 CONFIG_TRACE_EARLY_SIZE);
-		end = (char *)&hdr->ftrace[min(hdr->ftrace_count,
-					       hdr->ftrace_size)];
+		count = min(hdr->ftrace_count, hdr->ftrace_size);
+		end = (char *)&hdr->ftrace[count];
 		used = end - (char *)hdr;
 		printf("trace: copying %08lx bytes of early data from %x to %08lx\n",
 		       used, CONFIG_TRACE_EARLY_ADDR,
 		       (ulong)map_to_sysmem(buff));
+		printf("%lu traced function calls", count);
+		if (hdr->ftrace_count > hdr->ftrace_size) {
+			printf(" (%lu dropped due to overflow)",
+			       hdr->ftrace_count - hdr->ftrace_size);
+			hdr->ftrace_count = hdr->ftrace_size;
+		}
+		puts("\n");
 		memcpy(buff, hdr, used);
 #else
 		puts("trace: already enabled\n");
-- 
2.39.0.314.g84b9a713c41-goog