https://github.com/thetruestblue created
https://github.com/llvm/llvm-project/pull/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
>From db161e5c87eecbd5607f78e7afd00af183aa415c Mon Sep 17 00:00:00 2001
From: Blue Gaston <bgast...@apple.com>
Date: Fri, 14 Jun 2024 12:53:27 -0400
Subject: [PATCH] [LLDB] Don't cache module sp when Activate() fails.
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
---
lldb/source/Target/InstrumentationRuntime.cpp | 2 ++
1 file changed, 2 insertions(+)
diff --git a/lldb/source/Target/InstrumentationRuntime.cpp
b/lldb/source/Target/InstrumentationRuntime.cpp
index 9f22a1be20ccb..94f4ca353d7ef 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.
}
}
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