https://github.com/mchoo7 updated https://github.com/llvm/llvm-project/pull/178027
>From 9986846bb72373e70b181effbd3cb5d7d58825cb Mon Sep 17 00:00:00 2001 From: Minsoo Choo <[email protected]> Date: Sun, 25 Jan 2026 22:00:47 -0500 Subject: [PATCH 1/3] [lldb] [Process/FreeBSDKernel] Show crash info on start This is equivalent of kgdb_dmesg() in fbsd-kvm.c in FreeBSD kgdb(1) port. Crash info isn't printed in batch mode. Signed-off-by: Minsoo Choo <[email protected]> --- .../FreeBSDKernel/ProcessFreeBSDKernel.cpp | 125 +++++++++++++++++- .../FreeBSDKernel/ProcessFreeBSDKernel.h | 5 + 2 files changed, 129 insertions(+), 1 deletion(-) diff --git a/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp b/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp index c7da9f215972f..3dbeb736562e2 100644 --- a/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp +++ b/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp @@ -6,9 +6,12 @@ // //===----------------------------------------------------------------------===// +#include "lldb/Core/Debugger.h" #include "lldb/Core/Module.h" #include "lldb/Core/PluginManager.h" +#include "lldb/Symbol/Type.h" #include "lldb/Target/DynamicLoader.h" +#include "lldb/Utility/StreamString.h" #include "Plugins/DynamicLoader/FreeBSD-Kernel/DynamicLoaderFreeBSDKernel.h" #include "ProcessFreeBSDKernel.h" @@ -118,7 +121,12 @@ bool ProcessFreeBSDKernel::CanDebug(lldb::TargetSP target_sp, return true; } -void ProcessFreeBSDKernel::RefreshStateAfterStop() {} +void ProcessFreeBSDKernel::RefreshStateAfterStop() { + if (!m_displayed_crash_info) { + ShowCrashInfo(); + m_displayed_crash_info = true; + } +} bool ProcessFreeBSDKernel::DoUpdateThreadList(ThreadList &old_thread_list, ThreadList &new_thread_list) { @@ -277,6 +285,121 @@ lldb::addr_t ProcessFreeBSDKernel::FindSymbol(const char *name) { return sym ? sym->GetLoadAddress(&GetTarget()) : LLDB_INVALID_ADDRESS; } +void ProcessFreeBSDKernel::ShowCrashInfo() { + Status error; + + // Find msgbufp symbol (pointer to message buffer) + lldb::addr_t msgbufp_addr = FindSymbol("msgbufp"); + if (msgbufp_addr == LLDB_INVALID_ADDRESS) + return; + + // Read the pointer value + lldb::addr_t msgbufp = ReadPointerFromMemory(msgbufp_addr, error); + if (!error.Success() || msgbufp == LLDB_INVALID_ADDRESS) + return; + + // Get the type information for struct msgbuf from DWARF + TypeQuery query("msgbuf"); + TypeResults results; + GetTarget().GetImages().FindTypes(nullptr, query, results); + + uint64_t offset_msg_ptr = 0; + uint64_t offset_msg_size = 0; + uint64_t offset_msg_wseq = 0; + uint64_t offset_msg_rseq = 0; + + if (results.GetTypeMap().GetSize() > 0) { + // Found type info - use it to get field offsets + CompilerType msgbuf_type = + results.GetTypeMap().GetTypeAtIndex(0)->GetForwardCompilerType(); + + uint32_t num_fields = msgbuf_type.GetNumFields(); + for (uint32_t i = 0; i < num_fields; i++) { + std::string field_name; + uint64_t field_offset = 0; + uint32_t field_bitfield_bit_size = 0; + bool field_is_bitfield = false; + + msgbuf_type.GetFieldAtIndex(i, field_name, &field_offset, + &field_bitfield_bit_size, &field_is_bitfield); + + if (field_name == "msg_ptr") + offset_msg_ptr = field_offset / 8; // Convert bits to bytes + else if (field_name == "msg_size") + offset_msg_size = field_offset / 8; + else if (field_name == "msg_wseq") + offset_msg_wseq = field_offset / 8; + else if (field_name == "msg_rseq") + offset_msg_rseq = field_offset / 8; + } + } else { + // Fallback: use hardcoded offsets based on struct layout + // struct msgbuf layout (from sys/sys/msgbuf.h): + // char *msg_ptr; - offset 0 + // u_int msg_magic; - offset ptr_size + // u_int msg_size; - offset ptr_size + 4 + // u_int msg_wseq; - offset ptr_size + 8 + // u_int msg_rseq; - offset ptr_size + 12 + uint32_t ptr_size = GetAddressByteSize(); + offset_msg_ptr = 0; + offset_msg_size = ptr_size + 4; + offset_msg_wseq = ptr_size + 8; + offset_msg_rseq = ptr_size + 12; + } + + // Read struct msgbuf fields + lldb::addr_t bufp = ReadPointerFromMemory(msgbufp + offset_msg_ptr, error); + if (!error.Success() || bufp == LLDB_INVALID_ADDRESS) + return; + + uint32_t size = + ReadUnsignedIntegerFromMemory(msgbufp + offset_msg_size, 4, 0, error); + if (!error.Success() || size == 0) + return; + + uint32_t wseq = + ReadUnsignedIntegerFromMemory(msgbufp + offset_msg_wseq, 4, 0, error); + if (!error.Success()) + return; + + uint32_t rseq = + ReadUnsignedIntegerFromMemory(msgbufp + offset_msg_rseq, 4, 0, error); + if (!error.Success()) + return; + + // Convert sequences to positions + // MSGBUF_SEQ_TO_POS macro in FreeBSD: ((seq) % (size)) + uint32_t rseq_pos = rseq % size; + uint32_t wseq_pos = wseq % size; + + if (rseq_pos == wseq_pos) + return; + + // Print crash info at once using stream + lldb::StreamSP stream_sp = GetTarget().GetDebugger().GetAsyncOutputStream(); + if (!stream_sp) + return; + + stream_sp->Printf("\nUnread portion of the kernel message buffer:\n"); + + uint8_t c = 0; + while (rseq_pos != wseq_pos) { + size_t bytes_read = ReadMemory(bufp + rseq_pos, &c, 1, error); + if (!error.Success() || bytes_read != 1) + break; + + stream_sp->PutChar(c); + rseq_pos++; + if (rseq_pos >= size) + rseq_pos = 0; + } + + if (c != '\n') + stream_sp->PutChar('\n'); + stream_sp->PutChar('\n'); + stream_sp->Flush(); +} + #if LLDB_ENABLE_FBSDVMCORE ProcessFreeBSDKernelFVC::ProcessFreeBSDKernelFVC(lldb::TargetSP target_sp, diff --git a/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.h b/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.h index 81c567581dd56..7a17dd67f68c5 100644 --- a/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.h +++ b/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.h @@ -49,6 +49,11 @@ class ProcessFreeBSDKernel : public lldb_private::PostMortemProcess { lldb_private::ThreadList &new_thread_list) override; lldb::addr_t FindSymbol(const char *name); + +private: + void ShowCrashInfo(); + + bool m_displayed_crash_info = false; }; #endif // LLDB_SOURCE_PLUGINS_PROCESS_FREEBSDKERNEL_PROCESSFREEBSDKERNEL_H >From d96782c5636ff30617c094ef8c3c2b23791a0d01 Mon Sep 17 00:00:00 2001 From: Minsoo Choo <[email protected]> Date: Wed, 4 Feb 2026 10:06:17 -0500 Subject: [PATCH 2/3] fixup! [lldb] [Process/FreeBSDKernel] Show crash info on start Signed-off-by: Minsoo Choo <[email protected]> --- .../FreeBSDKernel/ProcessFreeBSDKernel.cpp | 53 +++++++++++++------ 1 file changed, 38 insertions(+), 15 deletions(-) diff --git a/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp b/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp index 3dbeb736562e2..375eeb3d68852 100644 --- a/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp +++ b/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp @@ -9,6 +9,7 @@ #include "lldb/Core/Debugger.h" #include "lldb/Core/Module.h" #include "lldb/Core/PluginManager.h" +#include "lldb/Interpreter/CommandInterpreter.h" #include "lldb/Symbol/Type.h" #include "lldb/Target/DynamicLoader.h" #include "lldb/Utility/StreamString.h" @@ -286,6 +287,12 @@ lldb::addr_t ProcessFreeBSDKernel::FindSymbol(const char *name) { } void ProcessFreeBSDKernel::ShowCrashInfo() { + Target &target = GetTarget(); + Debugger &debugger = target.GetDebugger(); + + if (!debugger.GetCommandInterpreter().IsInteractive()) + return; + Status error; // Find msgbufp symbol (pointer to message buffer) @@ -301,7 +308,7 @@ void ProcessFreeBSDKernel::ShowCrashInfo() { // Get the type information for struct msgbuf from DWARF TypeQuery query("msgbuf"); TypeResults results; - GetTarget().GetImages().FindTypes(nullptr, query, results); + target.GetImages().FindTypes(nullptr, query, results); uint64_t offset_msg_ptr = 0; uint64_t offset_msg_size = 0; @@ -376,26 +383,42 @@ void ProcessFreeBSDKernel::ShowCrashInfo() { return; // Print crash info at once using stream - lldb::StreamSP stream_sp = GetTarget().GetDebugger().GetAsyncOutputStream(); + lldb::StreamSP stream_sp = debugger.GetAsyncOutputStream(); if (!stream_sp) return; - stream_sp->Printf("\nUnread portion of the kernel message buffer:\n"); - - uint8_t c = 0; - while (rseq_pos != wseq_pos) { - size_t bytes_read = ReadMemory(bufp + rseq_pos, &c, 1, error); - if (!error.Success() || bytes_read != 1) - break; + stream_sp->PutCString("\nUnread portion of the kernel message buffer:\n"); + + // Read ring buffer in at most two chunks + if (rseq_pos < wseq_pos) { + // No wrap: read from rseq_pos to wseq_pos + size_t len = wseq_pos - rseq_pos; + std::string buf(len, '\0'); + size_t bytes_read = ReadMemory(bufp + rseq_pos, &buf[0], len, error); + if (error.Success() && bytes_read > 0) { + buf.resize(bytes_read); + *stream_sp << buf; + } + } else { + // Wrap around: read from rseq_pos to end, then from start to wseq_pos + size_t len1 = size - rseq_pos; + std::string buf1(len1, '\0'); + size_t bytes_read1 = ReadMemory(bufp + rseq_pos, &buf1[0], len1, error); + if (error.Success() && bytes_read1 > 0) { + buf1.resize(bytes_read1); + *stream_sp << buf1; + } - stream_sp->PutChar(c); - rseq_pos++; - if (rseq_pos >= size) - rseq_pos = 0; + if (wseq_pos > 0) { + std::string buf2(wseq_pos, '\0'); + size_t bytes_read2 = ReadMemory(bufp, &buf2[0], wseq_pos, error); + if (error.Success() && bytes_read2 > 0) { + buf2.resize(bytes_read2); + *stream_sp << buf2; + } + } } - if (c != '\n') - stream_sp->PutChar('\n'); stream_sp->PutChar('\n'); stream_sp->Flush(); } >From 793e17cf81958ec6b7a33d643949c37a24ce3416 Mon Sep 17 00:00:00 2001 From: Minsoo Choo <[email protected]> Date: Tue, 10 Feb 2026 09:17:31 -0500 Subject: [PATCH 3/3] fixup! [lldb] [Process/FreeBSDKernel] Show crash info on start Signed-off-by: Minsoo Choo <[email protected]> --- .../FreeBSDKernel/ProcessFreeBSDKernel.cpp | 22 +++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp b/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp index 375eeb3d68852..6b685b6f5ae64 100644 --- a/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp +++ b/lldb/source/Plugins/Process/FreeBSDKernel/ProcessFreeBSDKernel.cpp @@ -12,6 +12,8 @@ #include "lldb/Interpreter/CommandInterpreter.h" #include "lldb/Symbol/Type.h" #include "lldb/Target/DynamicLoader.h" +#include "lldb/Utility/LLDBLog.h" +#include "lldb/Utility/Log.h" #include "lldb/Utility/StreamString.h" #include "Plugins/DynamicLoader/FreeBSD-Kernel/DynamicLoaderFreeBSDKernel.h" @@ -321,6 +323,7 @@ void ProcessFreeBSDKernel::ShowCrashInfo() { results.GetTypeMap().GetTypeAtIndex(0)->GetForwardCompilerType(); uint32_t num_fields = msgbuf_type.GetNumFields(); + int field_found = 0; for (uint32_t i = 0; i < num_fields; i++) { std::string field_name; uint64_t field_offset = 0; @@ -330,14 +333,25 @@ void ProcessFreeBSDKernel::ShowCrashInfo() { msgbuf_type.GetFieldAtIndex(i, field_name, &field_offset, &field_bitfield_bit_size, &field_is_bitfield); - if (field_name == "msg_ptr") + if (field_name == "msg_ptr") { offset_msg_ptr = field_offset / 8; // Convert bits to bytes - else if (field_name == "msg_size") + field_found++; + } else if (field_name == "msg_size") { offset_msg_size = field_offset / 8; - else if (field_name == "msg_wseq") + field_found++; + } else if (field_name == "msg_wseq") { offset_msg_wseq = field_offset / 8; - else if (field_name == "msg_rseq") + field_found++; + } else if (field_name == "msg_rseq") { offset_msg_rseq = field_offset / 8; + field_found++; + } + } + + if (field_found != 4) { + LLDB_LOGF(GetLog(LLDBLog::Object), + "FreeBSDKernel: Could not find all required fields for msgbuf"); + return; } } else { // Fallback: use hardcoded offsets based on struct layout _______________________________________________ lldb-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
