Add setting to require hardware breakpoints.
When debugging read-only memory we cannot use software breakpoint. We
already have support for hardware breakpoints and users can specify them
with `-H`. However, there's no option to force LLDB to use hardware
breakpoints internally, for example while stepping.
This patch adds a setting target.require-hardware-breakpoint that forces
LLDB to always use hardware breakpoints. Because hardware breakpoints
are a limited resource and can fail to resolve, this patch also extends
error handling in thread plans, where breakpoints are used for stepping.
Differential revision: https://reviews.llvm.org/D54221
llvm-svn: 346920
diff --git a/lldb/source/Target/ThreadPlanStepThrough.cpp b/lldb/source/Target/ThreadPlanStepThrough.cpp
index b373edb..d1f3c22 100644
--- a/lldb/source/Target/ThreadPlanStepThrough.cpp
+++ b/lldb/source/Target/ThreadPlanStepThrough.cpp
@@ -58,7 +58,10 @@
->GetTarget()
.CreateBreakpoint(m_backstop_addr, true, false)
.get();
+
if (return_bp != nullptr) {
+ if (return_bp->IsHardware() && !return_bp->HasResolvedLocations())
+ m_could_not_resolve_hw_bp = true;
return_bp->SetThreadID(m_thread.GetID());
m_backstop_bkpt_id = return_bp->GetID();
return_bp->SetBreakpointKind("step-through-backstop");
@@ -135,7 +138,26 @@
}
bool ThreadPlanStepThrough::ValidatePlan(Stream *error) {
- return m_sub_plan_sp.get() != nullptr;
+ if (m_could_not_resolve_hw_bp) {
+ if (error)
+ error->PutCString(
+ "Could not create hardware breakpoint for thread plan.");
+ return false;
+ }
+
+ if (m_backstop_bkpt_id == LLDB_INVALID_BREAK_ID) {
+ if (error)
+ error->PutCString("Could not create backstop breakpoint.");
+ return false;
+ }
+
+ if (!m_sub_plan_sp.get()) {
+ if (error)
+ error->PutCString("Does not have a subplan.");
+ return false;
+ }
+
+ return true;
}
bool ThreadPlanStepThrough::DoPlanExplainsStop(Event *event_ptr) {
@@ -211,6 +233,7 @@
if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
m_thread.GetProcess()->GetTarget().RemoveBreakpointByID(m_backstop_bkpt_id);
m_backstop_bkpt_id = LLDB_INVALID_BREAK_ID;
+ m_could_not_resolve_hw_bp = false;
}
}