[Lldb-commits] [lldb] 05f0e86 - [lldb] Change lldb's breakpoint handling behavior (#96260)
via lldb-commits
lldb-commits at lists.llvm.org
Fri Jul 19 17:26:17 PDT 2024
Author: Jason Molenda
Date: 2024-07-19T17:26:13-07:00
New Revision: 05f0e86cc895181b3d2210458c78938f83353002
URL: https://github.com/llvm/llvm-project/commit/05f0e86cc895181b3d2210458c78938f83353002
DIFF: https://github.com/llvm/llvm-project/commit/05f0e86cc895181b3d2210458c78938f83353002.diff
LOG: [lldb] Change lldb's breakpoint handling behavior (#96260)
lldb today has two rules: When a thread stops at a BreakpointSite, we
set the thread's StopReason to be "breakpoint hit" (regardless if we've
actually hit the breakpoint, or if we've merely stopped *at* the
breakpoint instruction/point and haven't tripped it yet). And second,
when resuming a process, any thread sitting at a BreakpointSite is
silently stepped over the BreakpointSite -- because we've already
flagged the breakpoint hit when we stopped there originally.
In this patch, I change lldb to only set a thread's stop reason to
breakpoint-hit when we've actually executed the instruction/triggered
the breakpoint. When we resume, we only silently step past a
BreakpointSite that we've registered as hit. We preserve this state
across inferior function calls that the user may do while stopped, etc.
Also, when a user adds a new breakpoint at $pc while stopped, or changes
$pc to be the address of a BreakpointSite, we will silently step past
that breakpoint when the process resumes. This is purely a UX call, I
don't think there's any person who wants to set a breakpoint at $pc and
then hit it immediately on resuming.
One non-intuitive UX from this change, but I'm convinced it is
necessary: If you're stopped at a BreakpointSite that has not yet
executed, you `stepi`, you will hit the breakpoint and the pc will not
yet advance. This thread has not completed its stepi, and the thread
plan is still on the stack. If you then `continue` the thread, lldb will
now stop and say, "instruction step completed", one instruction past the
BreakpointSite. You can continue a second time to resume execution. I
discussed this with Jim, and trying to paper over this behavior will
lead to more complicated scenarios behaving non-intuitively. And mostly
it's the testsuite that was trying to instruction step past a breakpoint
and getting thrown off -- and I changed those tests to expect the new
behavior.
The bugs driving this change are all from lldb dropping the real stop
reason for a thread and setting it to breakpoint-hit when that was not
the case. Jim hit one where we have an aarch64 watchpoint that triggers
one instruction before a BreakpointSite. On this arch we are notified of
the watchpoint hit after the instruction has been unrolled -- we disable
the watchpoint, instruction step, re-enable the watchpoint and collect
the new value. But now we're on a BreakpointSite so the watchpoint-hit
stop reason is lost.
Another was reported by ZequanWu in
https://discourse.llvm.org/t/lldb-unable-to-break-at-start/78282 we
attach to/launch a process with the pc at a BreakpointSite and
misbehave. Caroline Tice mentioned it is also a problem they've had with
putting a breakpoint on _dl_debug_state.
The change to each Process plugin that does execution control is that
1. If we've stopped at a BreakpointSite that has not been executed yet,
we will call Thread::SetThreadStoppedAtUnexecutedBP(pc) to record
that. When the thread resumes, if the pc is still at the same site, we
will continue, hit the breakpoint, and stop again.
2. When we've actually hit a breakpoint (enabled for this thread or not),
the Process plugin should call Thread::SetThreadHitBreakpointSite().
When we go to resume the thread, we will push a step-over-breakpoint
ThreadPlan before resuming.
The biggest set of changes is to StopInfoMachException where we
translate a Mach Exception into a stop reason. The Mach exception codes
differ in a few places depending on the target (unambiguously), and I
didn't want to duplicate the new code for each target so I've tested
what mach exceptions we get for each action on each target, and
reorganized StopInfoMachException::CreateStopReasonWithMachException to
document these possible values, and handle them without specializing
based on the target arch.
rdar://123942164
Added:
Modified:
lldb/include/lldb/Target/Thread.h
lldb/source/Plugins/Process/Utility/StopInfoMachException.cpp
lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
lldb/source/Plugins/Process/scripted/ScriptedThread.cpp
lldb/source/Target/StopInfo.cpp
lldb/source/Target/Thread.cpp
lldb/test/API/functionalities/breakpoint/consecutive_breakpoints/TestConsecutiveBreakpoints.py
lldb/test/API/functionalities/breakpoint/step_over_breakpoint/TestStepOverBreakpoint.py
Removed:
################################################################################
diff --git a/lldb/include/lldb/Target/Thread.h b/lldb/include/lldb/Target/Thread.h
index 2ff1f50d497e2..d3e429e9256df 100644
--- a/lldb/include/lldb/Target/Thread.h
+++ b/lldb/include/lldb/Target/Thread.h
@@ -129,6 +129,7 @@ class Thread : public std::enable_shared_from_this<Thread>,
register_backup_sp; // You need to restore the registers, of course...
uint32_t current_inlined_depth;
lldb::addr_t current_inlined_pc;
+ lldb::addr_t stopped_at_unexecuted_bp;
};
/// Constructor
@@ -378,6 +379,26 @@ class Thread : public std::enable_shared_from_this<Thread>,
virtual void SetQueueLibdispatchQueueAddress(lldb::addr_t dispatch_queue_t) {}
+ /// When a thread stops at an enabled BreakpointSite that has not executed,
+ /// the Process plugin should call SetThreadStoppedAtUnexecutedBP(pc).
+ /// If that BreakpointSite was actually triggered (the instruction was
+ /// executed, for a software breakpoint), regardless of whether the
+ /// breakpoint is valid for this thread, SetThreadHitBreakpointSite()
+ /// should be called to record that fact.
+ ///
+ /// Depending on the structure of the Process plugin, it may be easiest
+ /// to call SetThreadStoppedAtUnexecutedBP(pc) unconditionally when at
+ /// a BreakpointSite, and later when it is known that it was triggered,
+ /// SetThreadHitBreakpointSite() can be called. These two methods
+ /// overwrite the same piece of state in the Thread, the last one
+ /// called on a Thread wins.
+ void SetThreadStoppedAtUnexecutedBP(lldb::addr_t pc) {
+ m_stopped_at_unexecuted_bp = pc;
+ }
+ void SetThreadHitBreakpointSite() {
+ m_stopped_at_unexecuted_bp = LLDB_INVALID_ADDRESS;
+ }
+
/// Whether this Thread already has all the Queue information cached or not
///
/// A Thread may be associated with a libdispatch work Queue at a given
@@ -1312,6 +1333,9 @@ class Thread : public std::enable_shared_from_this<Thread>,
bool m_should_run_before_public_stop; // If this thread has "stop others"
// private work to do, then it will
// set this.
+ lldb::addr_t m_stopped_at_unexecuted_bp; // Set to the address of a breakpoint
+ // instruction that we have not yet
+ // hit, but will hit when we resume.
const uint32_t m_index_id; ///< A unique 1 based index assigned to each thread
/// for easy UI/command line access.
lldb::RegisterContextSP m_reg_context_sp; ///< The register context for this
diff --git a/lldb/source/Plugins/Process/Utility/StopInfoMachException.cpp b/lldb/source/Plugins/Process/Utility/StopInfoMachException.cpp
index 25cee369d7ee3..f1853be12638e 100644
--- a/lldb/source/Plugins/Process/Utility/StopInfoMachException.cpp
+++ b/lldb/source/Plugins/Process/Utility/StopInfoMachException.cpp
@@ -488,38 +488,6 @@ const char *StopInfoMachException::GetDescription() {
return m_description.c_str();
}
-static StopInfoSP GetStopInfoForHardwareBP(Thread &thread, Target *target,
- uint32_t exc_data_count,
- uint64_t exc_sub_code,
- uint64_t exc_sub_sub_code) {
- // Try hardware watchpoint.
- if (target) {
- // The exc_sub_code indicates the data break address.
- WatchpointResourceSP wp_rsrc_sp =
- target->GetProcessSP()->GetWatchpointResourceList().FindByAddress(
- (addr_t)exc_sub_code);
- if (wp_rsrc_sp && wp_rsrc_sp->GetNumberOfConstituents() > 0) {
- return StopInfo::CreateStopReasonWithWatchpointID(
- thread, wp_rsrc_sp->GetConstituentAtIndex(0)->GetID());
- }
- }
-
- // Try hardware breakpoint.
- ProcessSP process_sp(thread.GetProcess());
- if (process_sp) {
- // The exc_sub_code indicates the data break address.
- lldb::BreakpointSiteSP bp_sp =
- process_sp->GetBreakpointSiteList().FindByAddress(
- (lldb::addr_t)exc_sub_code);
- if (bp_sp && bp_sp->IsEnabled()) {
- return StopInfo::CreateStopReasonWithBreakpointSiteID(thread,
- bp_sp->GetID());
- }
- }
-
- return nullptr;
-}
-
#if defined(__APPLE__)
const char *
StopInfoMachException::MachException::Name(exception_type_t exc_type) {
@@ -607,6 +575,25 @@ StopInfoSP StopInfoMachException::CreateStopReasonWithMachException(
target ? target->GetArchitecture().GetMachine()
: llvm::Triple::UnknownArch;
+ ProcessSP process_sp(thread.GetProcess());
+ RegisterContextSP reg_ctx_sp(thread.GetRegisterContext());
+ // Caveat: with x86 KDP if we've hit a breakpoint, the pc we
+ // receive is past the breakpoint instruction.
+ // If we have a breakpoints at 0x100 and 0x101, we hit the
+ // 0x100 breakpoint and the pc is reported at 0x101.
+ // We will initially mark this thread as being stopped at an
+ // unexecuted breakpoint at 0x101. Later when we see that
+ // we stopped for a Breakpoint reason, we will decrement the
+ // pc, and update the thread to record that we hit the
+ // breakpoint at 0x100.
+ // The fact that the pc may be off by one at this point
+ // (for an x86 KDP breakpoint hit) is not a problem.
+ addr_t pc = reg_ctx_sp->GetPC();
+ BreakpointSiteSP bp_site_sp =
+ process_sp->GetBreakpointSiteList().FindByAddress(pc);
+ if (bp_site_sp && bp_site_sp->IsEnabled())
+ thread.SetThreadStoppedAtUnexecutedBP(pc);
+
switch (exc_type) {
case 1: // EXC_BAD_ACCESS
case 2: // EXC_BAD_INSTRUCTION
@@ -633,171 +620,158 @@ StopInfoSP StopInfoMachException::CreateStopReasonWithMachException(
}
break;
+ // A mach exception comes with 2-4 pieces of data.
+ // The sub-codes are only provided for certain types
+ // of mach exceptions.
+ // [exc_type, exc_code, exc_sub_code, exc_sub_sub_code]
+ //
+ // Here are all of the EXC_BREAKPOINT, exc_type==6,
+ // exceptions we can receive.
+ //
+ // Instruction step:
+ // [6, 1, 0]
+ // Intel KDP [6, 3, ??]
+ // armv7 [6, 0x102, <stop-pc>] Same as software breakpoint!
+ //
+ // Software breakpoint:
+ // x86 [6, 2, 0]
+ // Intel KDP [6, 2, <bp-addr + 1>]
+ // arm64 [6, 1, <bp-addr>]
+ // armv7 [6, 0x102, <bp-addr>] Same as instruction step!
+ //
+ // Hardware breakpoint:
+ // x86 [6, 1, <bp-addr>, 0]
+ // x86/Rosetta not implemented, see software breakpoint
+ // arm64 [6, 1, <bp-addr>]
+ // armv7 not implemented, see software breakpoint
+ //
+ // Hardware watchpoint:
+ // x86 [6, 1, <accessed-addr>, 0] (both Intel hw and Rosetta)
+ // arm64 [6, 0x102, <accessed-addr>, 0]
+ // armv7 [6, 0x102, <accessed-addr>, 0]
+ //
+ // arm64 BRK instruction (imm arg not reflected in the ME)
+ // [ 6, 1, <addr-of-BRK-insn>]
+ //
+ // In order of codes mach exceptions:
+ // [6, 1, 0] - instruction step
+ // [6, 1, <bp-addr>] - hardware breakpoint or watchpoint
+ //
+ // [6, 2, 0] - software breakpoint
+ // [6, 2, <bp-addr + 1>] - software breakpoint
+ //
+ // [6, 3] - instruction step
+ //
+ // [6, 0x102, <stop-pc>] armv7 instruction step
+ // [6, 0x102, <bp-addr>] armv7 software breakpoint
+ // [6, 0x102, <accessed-addr>, 0] arm64/armv7 watchpoint
+
case 6: // EXC_BREAKPOINT
{
- bool is_actual_breakpoint = false;
- bool is_trace_if_actual_breakpoint_missing = false;
- switch (cpu) {
- case llvm::Triple::x86:
- case llvm::Triple::x86_64:
- if (exc_code == 1) // EXC_I386_SGL
- {
- if (!exc_sub_code) {
- // This looks like a plain trap.
- // Have to check if there is a breakpoint here as well. When you
- // single-step onto a trap, the single step stops you not to trap.
- // Since we also do that check below, let's just use that logic.
- is_actual_breakpoint = true;
- is_trace_if_actual_breakpoint_missing = true;
- } else {
- if (StopInfoSP stop_info =
- GetStopInfoForHardwareBP(thread, target, exc_data_count,
- exc_sub_code, exc_sub_sub_code))
- return stop_info;
- }
- } else if (exc_code == 2 || // EXC_I386_BPT
- exc_code == 3) // EXC_I386_BPTFLT
- {
- // KDP returns EXC_I386_BPTFLT for trace breakpoints
- if (exc_code == 3)
- is_trace_if_actual_breakpoint_missing = true;
-
- is_actual_breakpoint = true;
+ bool stopped_by_hitting_breakpoint = false;
+ bool stopped_by_completing_stepi = false;
+ bool stopped_watchpoint = false;
+ std::optional<addr_t> address;
+
+ // exc_code 1
+ if (exc_code == 1) {
+ if (exc_sub_code == 0) {
+ stopped_by_completing_stepi = true;
+ } else {
+ // Ambiguous: could be signalling a
+ // breakpoint or watchpoint hit.
+ stopped_by_hitting_breakpoint = true;
+ stopped_watchpoint = true;
+ address = exc_sub_code;
+ }
+ }
+
+ // exc_code 2
+ if (exc_code == 2) {
+ if (exc_sub_code == 0)
+ stopped_by_hitting_breakpoint = true;
+ else {
+ stopped_by_hitting_breakpoint = true;
+ // Intel KDP software breakpoint
if (!pc_already_adjusted)
pc_decrement = 1;
}
- break;
+ }
- case llvm::Triple::arm:
- case llvm::Triple::thumb:
- if (exc_code == 0x102) // EXC_ARM_DA_DEBUG
- {
- // LWP_TODO: We need to find the WatchpointResource that matches
- // the address, and evaluate its Watchpoints.
-
- // It's a watchpoint, then, if the exc_sub_code indicates a
- // known/enabled data break address from our watchpoint list.
- lldb::WatchpointSP wp_sp;
- if (target)
- wp_sp = target->GetWatchpointList().FindByAddress(
- (lldb::addr_t)exc_sub_code);
- if (wp_sp && wp_sp->IsEnabled()) {
- return StopInfo::CreateStopReasonWithWatchpointID(thread,
- wp_sp->GetID());
- } else {
- is_actual_breakpoint = true;
- is_trace_if_actual_breakpoint_missing = true;
- }
- } else if (exc_code == 1) // EXC_ARM_BREAKPOINT
- {
- is_actual_breakpoint = true;
- is_trace_if_actual_breakpoint_missing = true;
- } else if (exc_code == 0) // FIXME not EXC_ARM_BREAKPOINT but a kernel
- // is currently returning this so accept it
- // as indicating a breakpoint until the
- // kernel is fixed
- {
- is_actual_breakpoint = true;
- is_trace_if_actual_breakpoint_missing = true;
- }
- break;
+ // exc_code 3
+ if (exc_code == 3)
+ stopped_by_completing_stepi = true;
- case llvm::Triple::aarch64_32:
- case llvm::Triple::aarch64: {
- // xnu describes three things with type EXC_BREAKPOINT:
- //
- // exc_code 0x102 [EXC_ARM_DA_DEBUG], exc_sub_code addr-of-insn
- // Watchpoint access. exc_sub_code is the address of the
- // instruction which trigged the watchpoint trap.
- // debugserver may add the watchpoint number that was triggered
- // in exc_sub_sub_code.
- //
- // exc_code 1 [EXC_ARM_BREAKPOINT], exc_sub_code 0
- // Instruction step has completed.
- //
- // exc_code 1 [EXC_ARM_BREAKPOINT], exc_sub_code address-of-instruction
- // Software breakpoint instruction executed.
-
- if (exc_code == 1 && exc_sub_code == 0) // EXC_ARM_BREAKPOINT
- {
- // This is hit when we single instruction step aka MDSCR_EL1 SS bit 0
- // is set
- is_actual_breakpoint = true;
- is_trace_if_actual_breakpoint_missing = true;
- if (thread.GetTemporaryResumeState() != eStateStepping)
- not_stepping_but_got_singlestep_exception = true;
- }
- if (exc_code == 0x102) // EXC_ARM_DA_DEBUG
- {
- // LWP_TODO: We need to find the WatchpointResource that matches
- // the address, and evaluate its Watchpoints.
-
- // It's a watchpoint, then, if the exc_sub_code indicates a
- // known/enabled data break address from our watchpoint list.
- lldb::WatchpointSP wp_sp;
- if (target)
- wp_sp = target->GetWatchpointList().FindByAddress(
- (lldb::addr_t)exc_sub_code);
- if (wp_sp && wp_sp->IsEnabled()) {
- return StopInfo::CreateStopReasonWithWatchpointID(thread,
- wp_sp->GetID());
- }
- // EXC_ARM_DA_DEBUG seems to be reused for EXC_BREAKPOINT as well as
- // EXC_BAD_ACCESS
- if (thread.GetTemporaryResumeState() == eStateStepping)
- return StopInfo::CreateStopReasonToTrace(thread);
+ // exc_code 0x102
+ if (exc_code == 0x102 && exc_sub_code != 0) {
+ if (cpu == llvm::Triple::arm || cpu == llvm::Triple::thumb) {
+ stopped_by_hitting_breakpoint = true;
+ stopped_by_completing_stepi = true;
}
- // It looks like exc_sub_code has the 4 bytes of the instruction that
- // triggered the exception, i.e. our breakpoint opcode
- is_actual_breakpoint = exc_code == 1;
- break;
+ stopped_watchpoint = true;
+ address = exc_sub_code;
}
- default:
- break;
- }
+ // The Mach Exception may have been ambiguous --
+ // e.g. we stopped either because of a breakpoint
+ // or a watchpoint. We'll disambiguate which it
+ // really was.
- if (is_actual_breakpoint) {
- RegisterContextSP reg_ctx_sp(thread.GetRegisterContext());
+ if (stopped_by_hitting_breakpoint) {
addr_t pc = reg_ctx_sp->GetPC() - pc_decrement;
- ProcessSP process_sp(thread.CalculateProcess());
-
- lldb::BreakpointSiteSP bp_site_sp;
- if (process_sp)
+ if (address)
+ bp_site_sp =
+ process_sp->GetBreakpointSiteList().FindByAddress(*address);
+ if (!bp_site_sp && reg_ctx_sp) {
bp_site_sp = process_sp->GetBreakpointSiteList().FindByAddress(pc);
+ }
if (bp_site_sp && bp_site_sp->IsEnabled()) {
- // Update the PC if we were asked to do so, but only do so if we find
- // a breakpoint that we know about cause this could be a trap
- // instruction in the code
- if (pc_decrement > 0 && adjust_pc_if_needed)
- reg_ctx_sp->SetPC(pc);
-
- // If the breakpoint is for this thread, then we'll report the hit,
- // but if it is for another thread, we can just report no reason. We
- // don't need to worry about stepping over the breakpoint here, that
- // will be taken care of when the thread resumes and notices that
- // there's a breakpoint under the pc. If we have an operating system
- // plug-in, we might have set a thread specific breakpoint using the
- // operating system thread ID, so we can't make any assumptions about
- // the thread ID so we must always report the breakpoint regardless
- // of the thread.
+ // We've hit this breakpoint, whether it was intended for this thread
+ // or not. Clear this in the Tread object so we step past it on resume.
+ thread.SetThreadHitBreakpointSite();
+
+ // If we have an operating system plug-in, we might have set a thread
+ // specific breakpoint using the operating system thread ID, so we
+ // can't make any assumptions about the thread ID so we must always
+ // report the breakpoint regardless of the thread.
if (bp_site_sp->ValidForThisThread(thread) ||
- thread.GetProcess()->GetOperatingSystem() != nullptr)
+ thread.GetProcess()->GetOperatingSystem() != nullptr) {
+ // Update the PC if we were asked to do so, but only do so if we find
+ // a breakpoint that we know about cause this could be a trap
+ // instruction in the code
+ if (pc_decrement > 0 && adjust_pc_if_needed && reg_ctx_sp)
+ reg_ctx_sp->SetPC(pc);
return StopInfo::CreateStopReasonWithBreakpointSiteID(
thread, bp_site_sp->GetID());
- else if (is_trace_if_actual_breakpoint_missing)
- return StopInfo::CreateStopReasonToTrace(thread);
- else
+ } else {
return StopInfoSP();
+ }
}
+ }
- // Don't call this a trace if we weren't single stepping this thread.
- if (is_trace_if_actual_breakpoint_missing &&
- thread.GetTemporaryResumeState() == eStateStepping) {
- return StopInfo::CreateStopReasonToTrace(thread);
+ // Breakpoint-hit events are handled.
+ // Now handle watchpoints.
+
+ if (stopped_watchpoint && address) {
+ WatchpointResourceSP wp_rsrc_sp =
+ target->GetProcessSP()->GetWatchpointResourceList().FindByAddress(
+ *address);
+ if (wp_rsrc_sp && wp_rsrc_sp->GetNumberOfConstituents() > 0) {
+ return StopInfo::CreateStopReasonWithWatchpointID(
+ thread, wp_rsrc_sp->GetConstituentAtIndex(0)->GetID());
}
}
+
+ // Finally, handle instruction step.
+
+ if (stopped_by_completing_stepi) {
+ if (thread.GetTemporaryResumeState() != eStateStepping)
+ not_stepping_but_got_singlestep_exception = true;
+ else
+ return StopInfo::CreateStopReasonToTrace(thread);
+ }
+
} break;
case 7: // EXC_SYSCALL
diff --git a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
index f383b3d40a4f3..8b12b87eacbc6 100644
--- a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
+++ b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
@@ -377,24 +377,17 @@ void ProcessWindows::RefreshStateAfterStop() {
if (!stop_thread)
return;
- switch (active_exception->GetExceptionCode()) {
- case EXCEPTION_SINGLE_STEP: {
- RegisterContextSP register_context = stop_thread->GetRegisterContext();
- const uint64_t pc = register_context->GetPC();
- BreakpointSiteSP site(GetBreakpointSiteList().FindByAddress(pc));
- if (site && site->ValidForThisThread(*stop_thread)) {
- LLDB_LOG(log,
- "Single-stepped onto a breakpoint in process {0} at "
- "address {1:x} with breakpoint site {2}",
- m_session_data->m_debugger->GetProcess().GetProcessId(), pc,
- site->GetID());
- stop_info = StopInfo::CreateStopReasonWithBreakpointSiteID(*stop_thread,
- site->GetID());
- stop_thread->SetStopInfo(stop_info);
+ RegisterContextSP register_context = stop_thread->GetRegisterContext();
+ uint64_t pc = register_context->GetPC();
- return;
- }
+ // If we're at a BreakpointSite, mark this as an Unexecuted Breakpoint.
+ // We'll clear that state if we've actually executed the breakpoint.
+ BreakpointSiteSP site(GetBreakpointSiteList().FindByAddress(pc));
+ if (site && site->IsEnabled())
+ stop_thread->SetThreadStoppedAtUnexecutedBP(pc);
+ switch (active_exception->GetExceptionCode()) {
+ case EXCEPTION_SINGLE_STEP: {
auto *reg_ctx = static_cast<RegisterContextWindows *>(
stop_thread->GetRegisterContext().get());
uint32_t slot_id = reg_ctx->GetTriggeredHardwareBreakpointSlotId();
@@ -419,8 +412,6 @@ void ProcessWindows::RefreshStateAfterStop() {
}
case EXCEPTION_BREAKPOINT: {
- RegisterContextSP register_context = stop_thread->GetRegisterContext();
-
int breakpoint_size = 1;
switch (GetTarget().GetArchitecture().GetMachine()) {
case llvm::Triple::aarch64:
@@ -443,9 +434,9 @@ void ProcessWindows::RefreshStateAfterStop() {
}
// The current PC is AFTER the BP opcode, on all architectures.
- uint64_t pc = register_context->GetPC() - breakpoint_size;
+ pc = register_context->GetPC() - breakpoint_size;
- BreakpointSiteSP site(GetBreakpointSiteList().FindByAddress(pc));
+ site = GetBreakpointSiteList().FindByAddress(pc);
if (site) {
LLDB_LOG(log,
"detected breakpoint in process {0} at address {1:x} with "
@@ -453,6 +444,7 @@ void ProcessWindows::RefreshStateAfterStop() {
m_session_data->m_debugger->GetProcess().GetProcessId(), pc,
site->GetID());
+ stop_thread->SetThreadHitBreakpointSite();
if (site->ValidForThisThread(*stop_thread)) {
LLDB_LOG(log,
"Breakpoint site {0} is valid for this thread ({1:x}), "
diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
index 604c92369e9a2..9ab03c1fb8ff3 100644
--- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -1598,29 +1598,8 @@ bool ProcessGDBRemote::CalculateThreadStopInfo(ThreadGDBRemote *thread) {
// that have stop reasons, and if there is no entry for a thread, then it
// has no stop reason.
thread->GetRegisterContext()->InvalidateIfNeeded(true);
- if (!GetThreadStopInfoFromJSON(thread, m_jstopinfo_sp)) {
- // If a thread is stopped at a breakpoint site, set that as the stop
- // reason even if it hasn't executed the breakpoint instruction yet.
- // We will silently step over the breakpoint when we resume execution
- // and miss the fact that this thread hit the breakpoint.
- const size_t num_thread_ids = m_thread_ids.size();
- for (size_t i = 0; i < num_thread_ids; i++) {
- if (m_thread_ids[i] == thread->GetID() && m_thread_pcs.size() > i) {
- addr_t pc = m_thread_pcs[i];
- lldb::BreakpointSiteSP bp_site_sp =
- thread->GetProcess()->GetBreakpointSiteList().FindByAddress(pc);
- if (bp_site_sp) {
- if (bp_site_sp->ValidForThisThread(*thread)) {
- thread->SetStopInfo(
- StopInfo::CreateStopReasonWithBreakpointSiteID(
- *thread, bp_site_sp->GetID()));
- return true;
- }
- }
- }
- }
+ if (!GetThreadStopInfoFromJSON(thread, m_jstopinfo_sp))
thread->SetStopInfo(StopInfoSP());
- }
return true;
}
@@ -1729,6 +1708,12 @@ ThreadSP ProcessGDBRemote::SetThreadStopInfo(
if (ThreadSP memory_thread_sp = m_thread_list.GetBackingThread(thread_sp))
thread_sp = memory_thread_sp;
+ addr_t pc = thread_sp->GetRegisterContext()->GetPC();
+ BreakpointSiteSP bp_site_sp =
+ thread_sp->GetProcess()->GetBreakpointSiteList().FindByAddress(pc);
+ if (bp_site_sp && bp_site_sp->IsEnabled())
+ thread_sp->SetThreadStoppedAtUnexecutedBP(pc);
+
if (exc_type != 0) {
const size_t exc_data_size = exc_data.size();
@@ -1745,26 +1730,10 @@ ThreadSP ProcessGDBRemote::SetThreadStopInfo(
// to no reason.
if (!reason.empty() && reason != "none") {
if (reason == "trace") {
- addr_t pc = thread_sp->GetRegisterContext()->GetPC();
- lldb::BreakpointSiteSP bp_site_sp =
- thread_sp->GetProcess()->GetBreakpointSiteList().FindByAddress(
- pc);
-
- // If the current pc is a breakpoint site then the StopInfo should be
- // set to Breakpoint Otherwise, it will be set to Trace.
- if (bp_site_sp && bp_site_sp->ValidForThisThread(*thread_sp)) {
- thread_sp->SetStopInfo(
- StopInfo::CreateStopReasonWithBreakpointSiteID(
- *thread_sp, bp_site_sp->GetID()));
- } else
- thread_sp->SetStopInfo(
- StopInfo::CreateStopReasonToTrace(*thread_sp));
+ thread_sp->SetStopInfo(StopInfo::CreateStopReasonToTrace(*thread_sp));
handled = true;
} else if (reason == "breakpoint") {
- addr_t pc = thread_sp->GetRegisterContext()->GetPC();
- lldb::BreakpointSiteSP bp_site_sp =
- thread_sp->GetProcess()->GetBreakpointSiteList().FindByAddress(
- pc);
+ thread_sp->SetThreadHitBreakpointSite();
if (bp_site_sp) {
// If the breakpoint is for this thread, then we'll report the hit,
// but if it is for another thread, we can just report no reason.
@@ -1880,39 +1849,41 @@ ThreadSP ProcessGDBRemote::SetThreadStopInfo(
StopInfo::CreateStopReasonVForkDone(*thread_sp));
handled = true;
}
- } else if (!signo) {
- addr_t pc = thread_sp->GetRegisterContext()->GetPC();
- lldb::BreakpointSiteSP bp_site_sp =
- thread_sp->GetProcess()->GetBreakpointSiteList().FindByAddress(pc);
-
- // If a thread is stopped at a breakpoint site, set that as the stop
- // reason even if it hasn't executed the breakpoint instruction yet.
- // We will silently step over the breakpoint when we resume execution
- // and miss the fact that this thread hit the breakpoint.
- if (bp_site_sp && bp_site_sp->ValidForThisThread(*thread_sp)) {
- thread_sp->SetStopInfo(StopInfo::CreateStopReasonWithBreakpointSiteID(
- *thread_sp, bp_site_sp->GetID()));
- handled = true;
- }
}
if (!handled && signo && !did_exec) {
if (signo == SIGTRAP) {
// Currently we are going to assume SIGTRAP means we are either
// hitting a breakpoint or hardware single stepping.
+
+ // We can't disambiguate between stepping-to-a-breakpointsite and
+ // hitting-a-breakpointsite.
+ //
+ // A user can instruction-step, and be stopped at a BreakpointSite.
+ // Or a user can be sitting at a BreakpointSite,
+ // instruction-step which hits the breakpoint and the pc does not
+ // advance.
+ //
+ // In both cases, we're at a BreakpointSite when stopped, and
+ // the resume state was eStateStepping.
+
+ // Assume if we're at a BreakpointSite, we hit it.
handled = true;
addr_t pc =
thread_sp->GetRegisterContext()->GetPC() + m_breakpoint_pc_offset;
- lldb::BreakpointSiteSP bp_site_sp =
+ BreakpointSiteSP bp_site_sp =
thread_sp->GetProcess()->GetBreakpointSiteList().FindByAddress(
pc);
+ // We can't know if we hit it or not. So if we are stopped at
+ // a BreakpointSite, assume we hit it, and should step past the
+ // breakpoint when we resume. This is contrary to how we handle
+ // BreakpointSites in any other location, but we can't know for
+ // sure what happened so it's a reasonable default.
if (bp_site_sp) {
- // If the breakpoint is for this thread, then we'll report the hit,
- // but if it is for another thread, we can just report no reason.
- // We don't need to worry about stepping over the breakpoint here,
- // that will be taken care of when the thread resumes and notices
- // that there's a breakpoint under the pc.
+ if (bp_site_sp->IsEnabled())
+ thread_sp->SetThreadHitBreakpointSite();
+
if (bp_site_sp->ValidForThisThread(*thread_sp)) {
if (m_breakpoint_pc_offset != 0)
thread_sp->GetRegisterContext()->SetPC(pc);
@@ -1926,8 +1897,6 @@ ThreadSP ProcessGDBRemote::SetThreadStopInfo(
} else {
// If we were stepping then assume the stop was the result of the
// trace. If we were not stepping then report the SIGTRAP.
- // FIXME: We are still missing the case where we single step over a
- // trap instruction.
if (thread_sp->GetTemporaryResumeState() == eStateStepping)
thread_sp->SetStopInfo(
StopInfo::CreateStopReasonToTrace(*thread_sp));
diff --git a/lldb/source/Plugins/Process/scripted/ScriptedThread.cpp b/lldb/source/Plugins/Process/scripted/ScriptedThread.cpp
index 88a4ca3b0389f..d0d1508e85172 100644
--- a/lldb/source/Plugins/Process/scripted/ScriptedThread.cpp
+++ b/lldb/source/Plugins/Process/scripted/ScriptedThread.cpp
@@ -229,6 +229,17 @@ bool ScriptedThread::CalculateStopInfo() {
LLVM_PRETTY_FUNCTION, "Failed to get scripted thread stop info.", error,
LLDBLog::Thread);
+ // If we're at a BreakpointSite, mark that we stopped there and
+ // need to hit the breakpoint when we resume. This will be cleared
+ // if we CreateStopReasonWithBreakpointSiteID.
+ if (RegisterContextSP reg_ctx_sp = GetRegisterContext()) {
+ addr_t pc = reg_ctx_sp->GetPC();
+ if (BreakpointSiteSP bp_site_sp =
+ GetProcess()->GetBreakpointSiteList().FindByAddress(pc))
+ if (bp_site_sp->IsEnabled())
+ SetThreadStoppedAtUnexecutedBP(pc);
+ }
+
lldb::StopInfoSP stop_info_sp;
lldb::StopReason stop_reason_type;
diff --git a/lldb/source/Target/StopInfo.cpp b/lldb/source/Target/StopInfo.cpp
index 95f78056b1644..895306b5ef0d4 100644
--- a/lldb/source/Target/StopInfo.cpp
+++ b/lldb/source/Target/StopInfo.cpp
@@ -1365,6 +1365,8 @@ class StopInfoVForkDone : public StopInfo {
StopInfoSP StopInfo::CreateStopReasonWithBreakpointSiteID(Thread &thread,
break_id_t break_id) {
+ thread.SetThreadHitBreakpointSite();
+
return StopInfoSP(new StopInfoBreakpoint(thread, break_id));
}
diff --git a/lldb/source/Target/Thread.cpp b/lldb/source/Target/Thread.cpp
index e75f5a356cec2..2105efe9305fe 100644
--- a/lldb/source/Target/Thread.cpp
+++ b/lldb/source/Target/Thread.cpp
@@ -217,6 +217,7 @@ Thread::Thread(Process &process, lldb::tid_t tid, bool use_invalid_index_id)
m_process_wp(process.shared_from_this()), m_stop_info_sp(),
m_stop_info_stop_id(0), m_stop_info_override_stop_id(0),
m_should_run_before_public_stop(false),
+ m_stopped_at_unexecuted_bp(LLDB_INVALID_ADDRESS),
m_index_id(use_invalid_index_id ? LLDB_INVALID_INDEX32
: process.GetNextThreadIndexID(tid)),
m_reg_context_sp(), m_state(eStateUnloaded), m_state_mutex(),
@@ -519,6 +520,7 @@ bool Thread::CheckpointThreadState(ThreadStateCheckpoint &saved_state) {
saved_state.current_inlined_depth = GetCurrentInlinedDepth();
saved_state.m_completed_plan_checkpoint =
GetPlans().CheckpointCompletedPlans();
+ saved_state.stopped_at_unexecuted_bp = m_stopped_at_unexecuted_bp;
return true;
}
@@ -554,6 +556,7 @@ void Thread::RestoreThreadStateFromCheckpoint(
saved_state.current_inlined_depth);
GetPlans().RestoreCompletedPlanCheckpoint(
saved_state.m_completed_plan_checkpoint);
+ m_stopped_at_unexecuted_bp = saved_state.stopped_at_unexecuted_bp;
}
StateType Thread::GetState() const {
@@ -622,7 +625,15 @@ void Thread::SetupForResume() {
const addr_t thread_pc = reg_ctx_sp->GetPC();
BreakpointSiteSP bp_site_sp =
GetProcess()->GetBreakpointSiteList().FindByAddress(thread_pc);
- if (bp_site_sp) {
+ // If we're at a BreakpointSite which we have either
+ // 1. already triggered/hit, or
+ // 2. the Breakpoint was added while stopped, or the pc was moved
+ // to this BreakpointSite
+ // Step past the breakpoint before resuming.
+ // If we stopped at a breakpoint instruction/BreakpointSite location
+ // without hitting it, and we're still at that same address on
+ // resuming, then we want to hit the BreakpointSite when we resume.
+ if (bp_site_sp && m_stopped_at_unexecuted_bp != thread_pc) {
// Note, don't assume there's a ThreadPlanStepOverBreakpoint, the
// target may not require anything special to step over a breakpoint.
@@ -711,6 +722,7 @@ bool Thread::ShouldResume(StateType resume_state) {
if (need_to_resume) {
ClearStackFrames();
+ m_stopped_at_unexecuted_bp = LLDB_INVALID_ADDRESS;
// Let Thread subclasses do any special work they need to prior to resuming
WillResume(resume_state);
}
@@ -1894,6 +1906,7 @@ Unwind &Thread::GetUnwinder() {
void Thread::Flush() {
ClearStackFrames();
m_reg_context_sp.reset();
+ m_stopped_at_unexecuted_bp = LLDB_INVALID_ADDRESS;
}
bool Thread::IsStillAtLastBreakpointHit() {
diff --git a/lldb/test/API/functionalities/breakpoint/consecutive_breakpoints/TestConsecutiveBreakpoints.py b/lldb/test/API/functionalities/breakpoint/consecutive_breakpoints/TestConsecutiveBreakpoints.py
index 73de4a294388b..ecea28c6e1f6d 100644
--- a/lldb/test/API/functionalities/breakpoint/consecutive_breakpoints/TestConsecutiveBreakpoints.py
+++ b/lldb/test/API/functionalities/breakpoint/consecutive_breakpoints/TestConsecutiveBreakpoints.py
@@ -2,7 +2,6 @@
Test that we handle breakpoints on consecutive instructions correctly.
"""
-
import lldb
from lldbsuite.test.decorators import *
from lldbsuite.test.lldbtest import *
@@ -64,20 +63,30 @@ def test_single_step(self):
"""Test that single step stops at the second breakpoint."""
self.prepare_test()
+ # Instruction step to the next instruction
+ # We haven't executed breakpoint2 yet, we're sitting at it now.
+ step_over = False
+ self.thread.StepInstruction(step_over)
+
step_over = False
self.thread.StepInstruction(step_over)
+ # We've now hit the breakpoint and this StepInstruction has
+ # been interrupted, it is still sitting on the thread plan stack.
+
self.assertState(self.process.GetState(), lldb.eStateStopped)
self.assertEqual(
self.thread.GetFrameAtIndex(0).GetPCAddress().GetLoadAddress(self.target),
self.bkpt_address.GetLoadAddress(self.target),
)
- self.thread = lldbutil.get_one_thread_stopped_at_breakpoint(
- self.process, self.breakpoint2
- )
- self.assertIsNotNone(
- self.thread, "Expected one thread to be stopped at breakpoint 2"
- )
+
+ # One more instruction to complete the Step that was interrupted
+ # earlier.
+ self.thread.StepInstruction(step_over)
+ strm = lldb.SBStream()
+ self.thread.GetDescription(strm)
+ self.assertIn("instruction step into", strm.GetData())
+ self.assertIsNotNone(self.thread, "Expected to see that step-in had completed")
self.finish_test()
@@ -106,4 +115,7 @@ def test_single_step_thread_specific(self):
"Stop reason should be 'plan complete'",
)
+ # Hit our second breakpoint
+ self.process.Continue()
+
self.finish_test()
diff --git a/lldb/test/API/functionalities/breakpoint/step_over_breakpoint/TestStepOverBreakpoint.py b/lldb/test/API/functionalities/breakpoint/step_over_breakpoint/TestStepOverBreakpoint.py
index 3a7440a31677a..1315288b35c55 100644
--- a/lldb/test/API/functionalities/breakpoint/step_over_breakpoint/TestStepOverBreakpoint.py
+++ b/lldb/test/API/functionalities/breakpoint/step_over_breakpoint/TestStepOverBreakpoint.py
@@ -5,7 +5,6 @@
and eStopReasonPlanComplete when breakpoint's condition fails.
"""
-
import lldb
from lldbsuite.test.decorators import *
from lldbsuite.test.lldbtest import *
@@ -90,6 +89,11 @@ def test_step_instruction(self):
self.assertGreaterEqual(step_count, steps_expected)
break
+ # We did a `stepi` when we hit our last breakpoint, and the stepi was not
+ # completed yet, so when we resume it will complete (running process.Continue()
+ # would have the same result - we step one instruction and stop again when
+ # our interrupted stepi completes).
+ self.thread.StepInstruction(True)
# Run the process until termination
self.process.Continue()
self.assertState(self.process.GetState(), lldb.eStateExited)
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