[Lldb-commits] [lldb] 41f6aee - [LLDB] Don't cache module sp when Activate() fails. (#95586)

[via lldb-commits]

Author: thetruestblue
Date: 2024-06-18T07:23:28-07:00
New Revision: 41f6aee769a900558e58eba7b5f9044f8f8a05b7

URL: https://github.com/llvm/llvm-project/commit/41f6aee769a900558e58eba7b5f9044f8f8a05b7
DIFF: https://github.com/llvm/llvm-project/commit/41f6aee769a900558e58eba7b5f9044f8f8a05b7.diff

LOG: [LLDB] Don't cache module sp when Activate() fails. (#95586)

Currently, the instrumentation runtime is caching a library the first
time it sees it in the module list. However, in some rare cases on
Darwin, the cached pre-run unloaded modules are different from the
runtime module that is loaded at runtime. This patch removes the cached
module if the plugin fails to activate, ensuring that on subsequent
calls we don't try to activate using the unloaded cached module.

There are a few related bugs to fix in a follow up: CheckIfRuntimeValid
should have a stronger check to ensure the module is loaded and can be
activated. Further investigation in
UpdateSpecialBinariesFromNewImageInfos calling ModulesDidLoad when the
module list may have unloaded modules.

I have not included a test for the following reasons:
1. This is an incredibly rare occurance and is only observed in a
specific circumstance on Darwin. It is tied to behavior in the
DynamicLoader thai is not commonly encountered.

2. It is difficult to reproduce -- this bug requires precise conditions
on darwin and it is unclear how we'd reproduce that in a controlled
testing environment.

rdar://128971453

Added: 
    

Modified: 
    lldb/source/Target/InstrumentationRuntime.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/source/Target/InstrumentationRuntime.cpp b/lldb/source/Target/InstrumentationRuntime.cpp
index 9f22a1be20ccb..9da06e8e155af 100644
--- a/lldb/source/Target/InstrumentationRuntime.cpp
+++ b/lldb/source/Target/InstrumentationRuntime.cpp
@@ -60,6 +60,8 @@ void InstrumentationRuntime::ModulesDidLoad(
       if (CheckIfRuntimeIsValid(module_sp)) {
         SetRuntimeModuleSP(module_sp);
         Activate();
+        if (!IsActive())
+          SetRuntimeModuleSP({}); // Don't cache module if activation failed.
         return false; // Stop iterating, we're done.
       }
     }