[bolt] Use a fixed name for the kernel imageusers/xur-llvm/spr/bolt

Use a fixed name for the kernel image to process kernel profiles,
regardless of the presence of a build ID or not.

This is to address the issue when the provided kernel image lacks a
matching build ID. This name, "[kernel.kallsyms]", is the default
for kernel DSOs in the Linux kernel source code
(see https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/perf/util/dso.c#n428).

While "[guest.kernel.kallsyms]" is the kernel DSO name for guest kernel,
support for VM profiles is currently limited. Therefore, we can
skip this name for now.

1 files changed, 3 insertions, 1 deletions

diff --git a/bolt/lib/Profile/DataAggregator.cpp b/bolt/lib/Profile/DataAggregator.cpp
index e2b7038f42e6..3ee80db6f4e0 100644
--- a/bolt/lib/Profile/DataAggregator.cpp
+++ b/bolt/lib/Profile/DataAggregator.cpp
@@ -2097,6 +2097,8 @@ std::error_code DataAggregator::parseMMapEvents() {
            << "\" for profile matching\n";
     NameToUse = BuildIDBinaryName;
   }
+  if (BC->IsLinuxKernel)
+    NameToUse = "[kernel.kallsyms]";
 
   auto Range = GlobalMMapInfo.equal_range(NameToUse);
   for (MMapInfo &MMapInfo : llvm::make_second_range(make_range(Range))) {
@@ -2145,7 +2147,7 @@ std::error_code DataAggregator::parseMMapEvents() {
     // Update mapping size.
     const uint64_t EndAddress = MMapInfo.MMapAddress + MMapInfo.Size;
     const uint64_t Size = EndAddress - BinaryMMapInfo[MMapInfo.PID].BaseAddress;
-    if (Size > BinaryMMapInfo[MMapInfo.PID].Size)
+    if (!BC->IsLinuxKernel && Size > BinaryMMapInfo[MMapInfo.PID].Size)
       BinaryMMapInfo[MMapInfo.PID].Size = Size;
   }