Be explicit that cpu_reader assumes little endian.
Change-Id: I8dee8e8ece5608576347e34eb7849bc42f105051
diff --git a/src/traced/probes/ftrace/cpu_reader.cc b/src/traced/probes/ftrace/cpu_reader.cc
index 9fd3045b..7b88c5a 100644
--- a/src/traced/probes/ftrace/cpu_reader.cc
+++ b/src/traced/probes/ftrace/cpu_reader.cc
@@ -328,7 +328,10 @@
uint16_t size_bytes = table->ftrace_page_header_spec().size.size;
PERFETTO_CHECK(size_bytes >= 4);
uint32_t overwrite_and_size;
- if (!ReadAndAdvance<uint32_t>(&ptr, end_of_page, &overwrite_and_size))
+ // On little endian, we can just read a uint32_t and reject the rest of the
+ // number later.
+ if (!ReadAndAdvance<uint32_t>(&ptr, end_of_page,
+ base::AssumeLittleEndian(&overwrite_and_size)))
return 0;
page_header.size = (overwrite_and_size & 0x000000000000ffffull) >> 0;
@@ -337,6 +340,9 @@
PERFETTO_DCHECK(page_header.size <= base::kPageSize);
+ // Reject rest of the number, if applicable. On 32-bit, size_bytes - 4 will
+ // evaluate to 0 and this will be a no-op. On 64-bit, this will advance by 4
+ // bytes.
ptr += size_bytes - 4;
const uint8_t* const end = ptr + page_header.size;