Do report overlapping modules from lookupFrame()

We always get many modules that overlap ld.so. We have to report them
when we find them, or otherwise the unwinding will fail. dwfl apparently
doesn't mind the overlap in this case, so we don't have to clear the
cache before.

Change-Id: I68e9f6fe1653073b555755f546e743621e8c7919
Reviewed-by: Milian Wolff <milian.wolff@kdab.com>

1 files changed, 14 insertions, 2 deletions

diff --git a/app/perfsymboltable.cpp b/app/perfsymboltable.cpp
index 6daf0a6..0004f48 100644
--- a/app/perfsymboltable.cpp
+++ b/app/perfsymboltable.cpp
@@ -394,8 +394,20 @@ int PerfSymbolTable::lookupFrame(Dwarf_Addr ip, quint64 timestamp, bool isKernel
     if (elfIt != m_elfs.constEnd()) {
         binaryId = m_unwind->resolveString(elfIt.value().file.fileName().toLocal8Bit());
         elfStart = elfIt.key();
-        if (m_dwfl && !mod)
-            mod = reportElf(elfIt);
+        if (m_dwfl) {
+            if (mod) {
+                // If dwfl has a module and it's not the same as what we want, report the module
+                // we want. Many modules overlap ld.so, so if we've reported even one sample from
+                // ld.so we would otherwise be blocked from reporting anything that overlaps it.
+                Dwarf_Addr mod_start = 0;
+                dwfl_module_info(mod, nullptr, &mod_start, nullptr, nullptr, nullptr, nullptr,
+                                 nullptr);
+                if (elfIt.key() != mod_start)
+                    mod = reportElf(elfIt);
+            } else {
+                mod = reportElf(elfIt);
+            }
+        }
     }
 
     PerfUnwind::Location addressLocation(