[Lldb-commits] [PATCH] D100263: [lldb] [gdb-remote client] Remove breakpoints in forked processes

[Michał Górny via Phabricator via lldb-commits]

mgorny created this revision.
mgorny added reviewers: labath, emaste, krytarowski.
mgorny requested review of this revision.

Remove software breakpoints from forked processes in order to restore
the original program code before detaching it.


https://reviews.llvm.org/D100263

Files:
  lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
  lldb/test/Shell/Subprocess/clone-follow-parent-softbp.test
  lldb/test/Shell/Subprocess/fork-follow-parent-softbp.test


Index: lldb/test/Shell/Subprocess/fork-follow-parent-softbp.test
===================================================================
--- /dev/null
+++ lldb/test/Shell/Subprocess/fork-follow-parent-softbp.test
@@ -0,0 +1,12 @@
+# REQUIRES: native
+# UNSUPPORTED: system-windows
+# RUN: %clangxx_host %p/Inputs/fork.cpp -DTEST_FORK=fork -o %t
+# RUN: %lldb -b -s %s %t | FileCheck %s
+b parent_func
+b child_func
+process launch
+# CHECK-NOT: function run in parent
+# CHECK: stop reason = breakpoint
+continue
+# CHECK: function run in parent
+# CHECK: child exited: 0
Index: lldb/test/Shell/Subprocess/clone-follow-parent-softbp.test
===================================================================
--- /dev/null
+++ lldb/test/Shell/Subprocess/clone-follow-parent-softbp.test
@@ -0,0 +1,13 @@
+# REQUIRES: native && (system-linux || system-netbsd)
+# clone() tests fails on arm64 Linux, PR #49899
+# UNSUPPORTED: system-linux && target-aarch64
+# RUN: %clangxx_host %p/Inputs/fork.cpp -DTEST_CLONE -o %t
+# RUN: %lldb -b -s %s %t | FileCheck %s
+b parent_func
+b child_func
+process launch
+# CHECK-NOT: function run in parent
+# CHECK: stop reason = breakpoint
+continue
+# CHECK: function run in parent
+# CHECK: child exited: 0
Index: lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
===================================================================
--- lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -5436,13 +5436,39 @@
 void ProcessGDBRemote::DidFork(lldb::pid_t child_pid, lldb::tid_t child_tid) {
   Log *log(ProcessGDBRemoteLog::GetLogIfAllCategoriesSet(GDBR_LOG_PROCESS));
 
+  if (m_gdb_comm.SupportsGDBStoppointPacket(eBreakpointSoftware)) {
+    lldb::pid_t orig_pid = m_gdb_comm.GetCurrentProcessID();
+
+    if (!m_gdb_comm.SetCurrentThread(child_tid, child_pid)) {
+      LLDB_LOG(log, "ProcessGDBRemote::DidFork() unable to set pid/tid");
+      return;
+    }
+
+    // Disable all software breakpoints in the forked process
+    GetBreakpointSiteList().ForEach([this](BreakpointSite *bp_site) {
+      if (bp_site->IsEnabled() &&
+          (bp_site->GetType() == BreakpointSite::eSoftware ||
+           bp_site->GetType() == BreakpointSite::eExternal)) {
+        m_gdb_comm.SendGDBStoppointTypePacket(
+            eBreakpointSoftware, false, bp_site->GetLoadAddress(),
+            bp_site->GetTrapOpcodeMaxByteSize());
+      }
+    });
+
+    // Reset gdb-remote to the original process.  Thread ID does not really
+    // matter, the next command will set it anyway.
+    if (!m_gdb_comm.SetCurrentThread(m_thread_ids.front(), orig_pid)) {
+      LLDB_LOG(log, "ProcessGDBRemote::DidFork() unable to reset pid/tid");
+      return;
+    }
+  }
+
   LLDB_LOG(log, "Detaching forked child {0}", child_pid);
   Status error = m_gdb_comm.Detach(false, child_pid);
   if (error.Fail()) {
-      LLDB_LOG(log,
-               "ProcessGDBRemote::DidFork() detach packet send failed: {0}",
-                error.AsCString() ? error.AsCString() : "<unknown error>");
-      return;
+    LLDB_LOG(log, "ProcessGDBRemote::DidFork() detach packet send failed: {0}",
+             error.AsCString() ? error.AsCString() : "<unknown error>");
+    return;
   }
 }
 


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