Protect SuperPMI from crashes calling jitStartup

When we call jitStartup, we pass a JitHost interface that the JIT
calls to query for data. These queries look up in the recorded
MCH data, and could fail (and throw an exception) if data is
missing, which it can be for running non-matching altjit against
a collection. Protect these calls with exception handling.

Author: BruceForstall

src/ToolBox/superpmi/superpmi/jitinstance.cpp

@@ -190,7 +190,11 @@ HRESULT JitInstance::StartUp(char*          PathToJit,
     {
         mc      = firstContext;
         jitHost = new JitHost(*this);
-        pnjitStartup(jitHost);
+        if (!callJitStartup(jitHost))
+        {
+            LogError("jitStartup failed");
+            return -1;
+        }
     }
 
     pJitInstance = pngetJit();
@@ -256,7 +260,11 @@ bool JitInstance::reLoad(MethodContext* firstContext)
     {
         mc      = firstContext;
         jitHost = new JitHost(*this);
-        pnjitStartup(jitHost);
+        if (!callJitStartup(jitHost))
+        {
+            LogError("jitStartup failed");
+            return false;
+        }
     }
 
     pJitInstance = pngetJit();
@@ -465,17 +473,56 @@ void JitInstance::freeLongLivedArray(void* array)
     HeapFree(ourHeap, 0, array);
 }
 
+// Helper for calling pnjitStartup. Needed to allow SEH here.
+bool JitInstance::callJitStartup(ICorJitHost* jithost)
+{
+    // Calling into the collection, which could fail, especially
+    // for altjits. So protect the call.
+
+    struct Param : FilterSuperPMIExceptionsParam_CaptureException
+    {
+        JitInstance* pThis;
+        ICorJitHost* jithost;
+        bool         result;
+    } param;
+    param.pThis   = this;
+    param.jithost = jithost;
+    param.result  = false;
+
+    PAL_TRY(Param*, pParam, &param)
+    {
+        pParam->pThis->pnjitStartup(pParam->jithost);
+        pParam->result = true;
+    }
+    PAL_EXCEPT_FILTER(FilterSuperPMIExceptions_CaptureExceptionAndStop)
+    {
+        SpmiException e(&param.exceptionPointers);
+
+        LogError("failed to call jitStartup.");
+        e.ShowAndDeleteMessage();
+    }
+    PAL_ENDTRY
+
+    return param.result;
+}
+
 // Reset JitConfig, that stores Enviroment variables.
 bool JitInstance::resetConfig(MethodContext* firstContext)
 {
-    if (pnjitStartup != nullptr)
+    if (pnjitStartup == nullptr)
+    {
+        return false;
+    }
+
+    mc = firstContext;
+    ICorJitHost* newHost = new JitHost(*this);
+
+    if (!callJitStartup(newHost))
     {
-        mc                   = firstContext;
-        ICorJitHost* newHost = new JitHost(*this);
-        pnjitStartup(newHost);
-        delete static_cast<JitHost*>(jitHost);
-        jitHost = newHost;
-        return true;
+        return false;
     }
-    return false;
-}
+
+    delete static_cast<JitHost*>(jitHost);
+    jitHost = newHost;
+    return true;
+}

src/ToolBox/superpmi/superpmi/jitinstance.h

@@ -54,6 +54,8 @@ class JitInstance
     HRESULT StartUp(char* PathToJit, bool copyJit, bool breakOnDebugBreakorAV, MethodContext* firstContext);
     bool reLoad(MethodContext* firstContext);
 
+    bool callJitStartup(ICorJitHost* newHost);
+
     bool resetConfig(MethodContext* firstContext);
 
     Result CompileMethod(MethodContext* MethodToCompile, int mcIndex, bool collectThroughput);