Merge remote-tracking branch 'origin/4.3'

 Conflicts:
	app/perfsymboltable.cpp
	app/perfunwind.cpp

Change-Id: If343bb33fabeb60a3eab566769cf2c4dda88fcc5

4 files changed, 48 insertions, 17 deletions

diff --git a/app/main.cpp b/app/main.cpp
index 242676a..5a6023a 100644
--- a/app/main.cpp
+++ b/app/main.cpp
@@ -70,7 +70,7 @@ int main(int argc, char *argv[])
 {
     QCoreApplication app(argc, argv);
     app.setApplicationName(QLatin1String("perfparser"));
-    app.setApplicationVersion(QLatin1String("1.0"));
+    app.setApplicationVersion(QLatin1String("4.3"));
 
     QCommandLineParser parser;
     parser.setApplicationDescription(QLatin1String("Perf data parser and unwinder."));
diff --git a/app/perfsymboltable.cpp b/app/perfsymboltable.cpp
index f23b0f4..5501a68 100644
--- a/app/perfsymboltable.cpp
+++ b/app/perfsymboltable.cpp
@@ -37,7 +37,11 @@
 
 PerfSymbolTable::PerfSymbolTable(quint32 pid, Dwfl_Callbacks *callbacks, PerfUnwind *parent) :
     m_perfMapFile(QString::fromLatin1("/tmp/perf-%1.map").arg(pid)),
-    m_unwind(parent), m_firstElf(nullptr), m_callbacks(callbacks), m_pid(pid)
+    m_cacheIsDirty(false),
+    m_unwind(parent),
+    m_firstElf(nullptr),
+    m_callbacks(callbacks),
+    m_pid(pid)
 {
     m_dwfl = dwfl_begin(m_callbacks);
 }
@@ -422,8 +426,10 @@ Dwfl_Module *PerfSymbolTable::reportElf(const PerfElfMap::ElfInfo& info)
                 m_dwfl, info.originalFileName.constData(),
                 info.localFile.absoluteFilePath().toLocal8Bit().constData(), -1, info.addr,
                 false);
-    if (!ret)
+    if (!ret) {
         reportError(info, dwfl_errmsg(dwfl_errno()));
+        m_cacheIsDirty = true;
+    }
 
     return ret;
 }
@@ -632,4 +638,6 @@ void PerfSymbolTable::clearCache()
     // Throw out the dwfl state
     dwfl_end(m_dwfl);
     m_dwfl = dwfl_begin(m_callbacks);
+
+    m_cacheIsDirty = false;
 }
diff --git a/app/perfsymboltable.h b/app/perfsymboltable.h
index 840fa93..4f9503b 100644
--- a/app/perfsymboltable.h
+++ b/app/perfsymboltable.h
@@ -72,6 +72,7 @@ public:
 
     Dwfl *attachDwfl(void *arg);
     void clearCache();
+    bool cacheIsDirty() const { return m_cacheIsDirty; }
 
 private:
 
@@ -83,6 +84,7 @@ private:
     QFile m_perfMapFile;
     QVector<PerfMapSymbol> m_perfMap;
     QHash<Dwarf_Addr, AddressCacheEntry> m_addressCache;
+    bool m_cacheIsDirty;
 
     PerfUnwind *m_unwind;
     Dwfl *m_dwfl;
diff --git a/app/perfunwind.cpp b/app/perfunwind.cpp
index cf86b72..0878dbb 100644
--- a/app/perfunwind.cpp
+++ b/app/perfunwind.cpp
@@ -304,10 +304,14 @@ static int frameCallback(Dwfl_Frame *state, void *arg)
 
     Dwarf_Addr pc_adjusted = pc - (isactivation ? 0 : 1);
 
+    auto* symbolTable = ui->unwind->symbolTable(ui->sample->pid());
     // isKernel = false as unwinding generally only works on user code
     bool isInterworking = false;
-    ui->frames.append(ui->unwind->symbolTable(ui->sample->pid())->lookupFrame(
-                          pc_adjusted, false, &isInterworking));
+    const auto frame = symbolTable->lookupFrame(pc_adjusted, false, &isInterworking);
+    if (symbolTable->cacheIsDirty())
+        return DWARF_CB_ABORT;
+
+    ui->frames.append(frame);
     if (isInterworking && ui->frames.length() == 1)
         ui->isInterworking = true;
     return DWARF_CB_OK;
@@ -375,6 +379,9 @@ void PerfUnwind::resolveCallchain()
                                               ip, isKernel,
                                               &m_currentUnwind.isInterworking));
         }
+
+        if (symbols->cacheIsDirty())
+            break;
     }
 }
 
@@ -388,23 +395,37 @@ void PerfUnwind::analyze(const PerfRecordSample &sample)
     if (m_stats.enabled) // don't do any time intensive work in stats mode
         return;
 
-    m_currentUnwind.isInterworking = false;
-    m_currentUnwind.firstGuessedFrame = -1;
-    m_currentUnwind.sample = &sample;
-    m_currentUnwind.frames.clear();
-
     const bool isKernel = ipIsInKernelSpace(sample.ip());
 
     PerfSymbolTable *userSymbols = symbolTable(sample.pid());
-    userSymbols->updatePerfMap();
 
-    // Do this before any lookupFrame() calls; we want to clear the caches if timestamps reset.
-    Dwfl *userDwfl = userSymbols->attachDwfl(&m_currentUnwind);
-    if (sample.callchain().length() > 0)
-        resolveCallchain();
+    for (int unwindingAttempt = 0; unwindingAttempt < 2; ++unwindingAttempt) {
+        m_currentUnwind.isInterworking = false;
+        m_currentUnwind.firstGuessedFrame = -1;
+        m_currentUnwind.sample = &sample;
+        m_currentUnwind.frames.clear();
+
+        userSymbols->updatePerfMap();
+
+        Dwfl *userDwfl = userSymbols->attachDwfl(&m_currentUnwind);
+        if (sample.callchain().length() > 0)
+            resolveCallchain();
 
-    if (userDwfl && sample.registerAbi() != 0 && sample.userStack().length() > 0)
-        unwindStack(userDwfl);
+        // only try to unwind when resolveCallchain did not dirty the cache
+        if (!userSymbols->cacheIsDirty()) {
+            if (userDwfl && sample.registerAbi() != 0 && sample.userStack().length() > 0)
+                unwindStack(userDwfl);
+            else
+                break;
+        }
+
+        // when the cache is dirty, we clean it up and try again, otherwise we can
+        // stop as unwinding should have succeeded
+        if (userSymbols->cacheIsDirty())
+            userSymbols->clearCache(); // fail, try again
+        else
+            break; // success
+    }
 
     // If nothing was found, at least look up the IP
     if (m_currentUnwind.frames.isEmpty()) {