[Lldb-commits] [lldb] [lldb][Process/FreeBSDKernelCore] Improve error handling (PR #191423)
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Fri Apr 10 07:16:42 PDT 2026
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-lldb
Author: Minsoo Choo (mchoo7)
<details>
<summary>Changes</summary>
Improve error handling with the following changes:
- If `kvm_open2()` fails in `DoLoadCore()`, log error with a message obtained from the function.
- Return false or continue for loop if memory read fails.
- Rename `!error.Success()` to `error.Fail()` for readability (NFC).
---
Full diff: https://github.com/llvm/llvm-project/pull/191423.diff
1 Files Affected:
- (modified) lldb/source/Plugins/Process/FreeBSD-Kernel-Core/ProcessFreeBSDKernelCore.cpp (+64-9)
``````````diff
diff --git a/lldb/source/Plugins/Process/FreeBSD-Kernel-Core/ProcessFreeBSDKernelCore.cpp b/lldb/source/Plugins/Process/FreeBSD-Kernel-Core/ProcessFreeBSDKernelCore.cpp
index e129a592d0968..3ec46ea7fdf25 100644
--- a/lldb/source/Plugins/Process/FreeBSD-Kernel-Core/ProcessFreeBSDKernelCore.cpp
+++ b/lldb/source/Plugins/Process/FreeBSD-Kernel-Core/ProcessFreeBSDKernelCore.cpp
@@ -193,15 +193,18 @@ Status ProcessFreeBSDKernelCore::DoLoadCore() {
return Status::FromErrorString(
"ProcessFreeBSDKernelCore: no executable module set on target");
+ char errbuf[_POSIX2_LINE_MAX];
m_kvm = kvm_open2(executable->GetFileSpec().GetPath().c_str(),
- GetCoreFile().GetPath().c_str(), O_RDWR, nullptr, nullptr);
+ GetCoreFile().GetPath().c_str(), O_RDWR, errbuf, nullptr);
- if (!m_kvm)
+ if (!m_kvm) {
+ LLDB_LOGF(GetLog(LLDBLog::Process), "FreeBSD-Kernel-Core: %s", errbuf);
return Status::FromErrorStringWithFormat(
"ProcessFreeBSDKernelCore: kvm_open2 failed for core '%s' "
"with kernel '%s'",
GetCoreFile().GetPath().c_str(),
executable->GetFileSpec().GetPath().c_str());
+ }
SetKernelDisplacement();
@@ -275,25 +278,52 @@ bool ProcessFreeBSDKernelCore::DoUpdateThreadList(ThreadList &old_thread_list,
// struct field offsets are written as symbols so that we don't have
// to figure them out ourselves
+ // Process-related offsets:
int32_t offset_p_list = ReadSignedIntegerFromMemory(
FindSymbol("proc_off_p_list"), 4, -1, error);
+ if (error.Fail())
+ return false;
+
int32_t offset_p_pid =
ReadSignedIntegerFromMemory(FindSymbol("proc_off_p_pid"), 4, -1, error);
+ if (error.Fail())
+ return false;
+
int32_t offset_p_threads = ReadSignedIntegerFromMemory(
FindSymbol("proc_off_p_threads"), 4, -1, error);
+ if (error.Fail())
+ return false;
+
int32_t offset_p_comm = ReadSignedIntegerFromMemory(
FindSymbol("proc_off_p_comm"), 4, -1, error);
+ if (error.Fail())
+ return false;
+ // Thread-related offsets:
int32_t offset_td_tid = ReadSignedIntegerFromMemory(
FindSymbol("thread_off_td_tid"), 4, -1, error);
+ if (error.Fail())
+ return false;
+
int32_t offset_td_plist = ReadSignedIntegerFromMemory(
FindSymbol("thread_off_td_plist"), 4, -1, error);
+ if (error.Fail())
+ return false;
+
int32_t offset_td_pcb = ReadSignedIntegerFromMemory(
FindSymbol("thread_off_td_pcb"), 4, -1, error);
+ if (error.Fail())
+ return false;
+
int32_t offset_td_oncpu = ReadSignedIntegerFromMemory(
FindSymbol("thread_off_td_oncpu"), 4, -1, error);
+ if (error.Fail())
+ return false;
+
int32_t offset_td_name = ReadSignedIntegerFromMemory(
FindSymbol("thread_off_td_name"), 4, -1, error);
+ if (error.Fail())
+ return false;
// Fail if we were not able to read any of the offsets.
if (offset_p_list == -1 || offset_p_pid == -1 || offset_p_threads == -1 ||
@@ -305,12 +335,18 @@ bool ProcessFreeBSDKernelCore::DoUpdateThreadList(ThreadList &old_thread_list,
// dumppcb contains its PCB
int32_t dumptid =
ReadSignedIntegerFromMemory(FindSymbol("dumptid"), 4, -1, error);
+ if (error.Fail())
+ return false;
+
lldb::addr_t dumppcb = FindSymbol("dumppcb");
// stoppcbs is an array of PCBs on all CPUs.
// Each element is of size pcb_size.
int32_t pcbsize =
ReadSignedIntegerFromMemory(FindSymbol("pcb_size"), 4, -1, error);
+ if (error.Fail())
+ return false;
+
lldb::addr_t stoppcbs = FindSymbol("stoppcbs");
// Read stopped_cpus bitmask and mp_maxid for CPU validation.
@@ -371,24 +407,39 @@ bool ProcessFreeBSDKernelCore::DoUpdateThreadList(ThreadList &old_thread_list,
// process' command-line string
char comm[fbsd_maxcomlen + 1];
ReadCStringFromMemory(proc + offset_p_comm, comm, sizeof(comm), error);
+ if (error.Fail())
+ continue;
// Iterate through a linked list of all process' threads
// the initial thread is found in process' p_threads, subsequent
- // elements are linked via td_plist field
+ // elements are linked via td_plist field.
+ // If reading memory fails, skip to the next thread.
for (lldb::addr_t td =
ReadPointerFromMemory(proc + offset_p_threads, error);
- td != 0; td = ReadPointerFromMemory(td + offset_td_plist, error)) {
+ error.Success() && td != 0;
+ td = ReadPointerFromMemory(td + offset_td_plist, error)) {
int32_t tid =
ReadSignedIntegerFromMemory(td + offset_td_tid, 4, -1, error);
+ if (error.Fail())
+ continue;
+
lldb::addr_t pcb_addr =
ReadPointerFromMemory(td + offset_td_pcb, error);
+ if (error.Fail())
+ continue;
+
// whether process was on CPU (-1 if not, otherwise CPU number)
int32_t oncpu =
ReadSignedIntegerFromMemory(td + offset_td_oncpu, 4, -2, error);
+ if (error.Fail())
+ continue;
+
// thread name
char thread_name[fbsd_maxcomlen + 1];
ReadCStringFromMemory(td + offset_td_name, thread_name,
sizeof(thread_name), error);
+ if (error.Fail())
+ continue;
// If we failed to read TID, ignore this thread.
if (tid == -1)
@@ -441,6 +492,10 @@ bool ProcessFreeBSDKernelCore::DoUpdateThreadList(ThreadList &old_thread_list,
new_thread_list.AddThread(static_cast<ThreadSP>(thread));
}
+
+ // If reading thread list has failed, return with false.
+ if (error.Fail())
+ return false;
}
} else {
const uint32_t num_threads = old_thread_list.GetSize(false);
@@ -504,7 +559,7 @@ void ProcessFreeBSDKernelCore::PrintUnreadMessage() {
// Read the pointer value
lldb::addr_t msgbufp = ReadPointerFromMemory(msgbufp_addr, error);
- if (!error.Success() || msgbufp == LLDB_INVALID_ADDRESS)
+ if (error.Fail() || msgbufp == LLDB_INVALID_ADDRESS)
return;
// Get the type information for struct msgbuf from DWARF
@@ -569,22 +624,22 @@ void ProcessFreeBSDKernelCore::PrintUnreadMessage() {
// Read struct msgbuf fields
lldb::addr_t bufp = ReadPointerFromMemory(msgbufp + offset_msg_ptr, error);
- if (!error.Success() || bufp == LLDB_INVALID_ADDRESS)
+ if (error.Fail() || bufp == LLDB_INVALID_ADDRESS)
return;
uint32_t size =
ReadUnsignedIntegerFromMemory(msgbufp + offset_msg_size, 4, 0, error);
- if (!error.Success() || size == 0)
+ if (error.Fail() || size == 0)
return;
uint32_t wseq =
ReadUnsignedIntegerFromMemory(msgbufp + offset_msg_wseq, 4, 0, error);
- if (!error.Success())
+ if (error.Fail())
return;
uint32_t rseq =
ReadUnsignedIntegerFromMemory(msgbufp + offset_msg_rseq, 4, 0, error);
- if (!error.Success())
+ if (error.Fail())
return;
// Convert sequences to positions
``````````
</details>
https://github.com/llvm/llvm-project/pull/191423
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