[Lldb-commits] [lldb] 60b90b5 - [lldb][DynamicLoader] Fix lldb unable to stop at _dl_debug_state if user set it before the process launched. (#88792)

[via lldb-commits]

Author: Zequan Wu
Date: 2024-04-17T16:09:38-04:00
New Revision: 60b90b523323f8196a9e4a68b1f33358624c09eb

URL: https://github.com/llvm/llvm-project/commit/60b90b523323f8196a9e4a68b1f33358624c09eb
DIFF: https://github.com/llvm/llvm-project/commit/60b90b523323f8196a9e4a68b1f33358624c09eb.diff

LOG: [lldb][DynamicLoader] Fix lldb unable to stop at _dl_debug_state if user set it before the process launched. (#88792)

If user sets a breakpoint at `_dl_debug_state` before the process
launched, the breakpoint is not resolved yet. When lldb loads dynamic
loader module, it's created with `Target::GetOrCreateModule` which
notifies any pending breakpoint to resolve. However, the module's
sections are not loaded at this time. They are loaded after returned
from
[Target::GetOrCreateModule](https://github.com/llvm/llvm-project/blob/0287a5cc4e2a5ded1ae2e4079f91052e6a6b8d9b/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp#L574-L577).
This change fixes it by manually resolving breakpoints after creating
dynamic loader module.

Added: 
    

Modified: 
    lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp
    lldb/test/API/functionalities/breakpoint/breakpoint_command/TestBreakpointCommand.py

Removed: 
    


################################################################################
diff  --git a/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp b/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp
index 9baf86da4dc799..9fa245fc41d40c 100644
--- a/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp
+++ b/lldb/source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp
@@ -571,10 +571,17 @@ ModuleSP DynamicLoaderPOSIXDYLD::LoadInterpreterModule() {
   FileSpec file(info.GetName().GetCString());
   ModuleSpec module_spec(file, target.GetArchitecture());
 
-  if (ModuleSP module_sp = target.GetOrCreateModule(module_spec,
-                                                    true /* notify */)) {
+  // Don't notify that module is added here because its loading section
+  // addresses are not updated yet. We manually notify it below.
+  if (ModuleSP module_sp =
+          target.GetOrCreateModule(module_spec, /*notify=*/false)) {
     UpdateLoadedSections(module_sp, LLDB_INVALID_ADDRESS, m_interpreter_base,
                          false);
+    // Manually notify that dynamic linker is loaded after updating load section
+    // addersses so that breakpoints can be resolved.
+    ModuleList module_list;
+    module_list.Append(module_sp);
+    target.ModulesDidLoad(module_list);
     m_interpreter_module = module_sp;
     return module_sp;
   }

diff  --git a/lldb/test/API/functionalities/breakpoint/breakpoint_command/TestBreakpointCommand.py b/lldb/test/API/functionalities/breakpoint/breakpoint_command/TestBreakpointCommand.py
index ea242952e409ec..850235fdcefa70 100644
--- a/lldb/test/API/functionalities/breakpoint/breakpoint_command/TestBreakpointCommand.py
+++ b/lldb/test/API/functionalities/breakpoint/breakpoint_command/TestBreakpointCommand.py
@@ -671,3 +671,20 @@ def test_breakpoint_statistics_hitcount(self):
         self.assertNotEqual(breakpoints_stats, None)
         for breakpoint_stats in breakpoints_stats:
             self.assertIn("hitCount", breakpoint_stats)
+
+    @skipIf(oslist=no_match(["linux"]))
+    def test_break_at__dl_debug_state(self):
+        """
+        Test lldb is able to stop at _dl_debug_state if it is set before the
+        process is launched.
+        """
+        self.build()
+        exe = self.getBuildArtifact("a.out")
+        self.runCmd("target create %s" % exe)
+        bpid = lldbutil.run_break_set_by_symbol(
+            self, "_dl_debug_state", num_expected_locations=0
+        )
+        self.runCmd("run")
+        self.assertIsNotNone(
+            lldbutil.get_one_thread_stopped_at_breakpoint_id(self.process(), bpid)
+        )