================
@@ -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);
----------------
DavidSpickett wrote:
Why do we do this one byte at a time?
>From what I gather, this message buffer tells us the size of each message, so
>we can we just try to read the whole message at once?
Maybe I am missing a corner case here.
https://github.com/llvm/llvm-project/pull/178027
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