https://github.com/Jlalond created 
https://github.com/llvm/llvm-project/pull/140150

Recently, I was on an issue that generated a large number of Coredumps, and 
every time in both LLDB and GDB the signal was just `SIGSEGV`.

This was frustrating because we would expect a `SIGSEGV` to have an address, or 
ideally even bounds. After some digging I found the `si_code` consistently was 
-6. With some help from [@cdown](https://github.com/cdown), we found neither 
LLDB or GDB supports the si_codes sent from [user 
space](https://github.com/torvalds/linux/blob/master/include/uapi/asm-generic/siginfo.h#L185).

Excerpted from the sigaction man page.
```
       For a regular signal, the following list shows the values which
       can be placed in si_code for any signal, along with the reason
       that the signal was generated.
```

For which I added all of the si_codes to every Linux signal. Now for the 
Coredump that triggered this whole investigation we get the accurate and now 
very informative summary.

<img width="524" alt="image" 
src="https://github.com/user-attachments/assets/5149f781-ef21-4491-a077-8fac862fbc20";
 />


Importantly, I didn't add an equivalent of `siginfo_t` to ELFSigInfo, and I 
think we should open an issue for this to make a (build) platform agnostic 
struct of siginfo_t. I'll defer to your expertise @labath and @DavidSpickett 


>From 86ec6c076b9cf8e7afeb7d6bb0e334434f6e0d9e Mon Sep 17 00:00:00 2001
From: Jacob Lalonde <jalalo...@fb.com>
Date: Thu, 15 May 2025 13:57:11 -0700
Subject: [PATCH 1/4] Update ThreadElfCore

---
 lldb/include/lldb/Target/UnixSignals.h          |  6 ++++--
 .../Plugins/Process/Utility/LinuxSignals.cpp    | 17 ++++++++++++++---
 .../Plugins/Process/elf-core/ThreadElfCore.cpp  | 10 +++++++---
 .../Plugins/Process/elf-core/ThreadElfCore.h    |  6 ++++++
 lldb/source/Target/UnixSignals.cpp              |  9 +++++++--
 5 files changed, 38 insertions(+), 10 deletions(-)

diff --git a/lldb/include/lldb/Target/UnixSignals.h 
b/lldb/include/lldb/Target/UnixSignals.h
index b3605ccefddbe..a1807d69f329b 100644
--- a/lldb/include/lldb/Target/UnixSignals.h
+++ b/lldb/include/lldb/Target/UnixSignals.h
@@ -36,7 +36,9 @@ class UnixSignals {
                        std::optional<int32_t> code = std::nullopt,
                        std::optional<lldb::addr_t> addr = std::nullopt,
                        std::optional<lldb::addr_t> lower = std::nullopt,
-                       std::optional<lldb::addr_t> upper = std::nullopt) const;
+                       std::optional<lldb::addr_t> upper = std::nullopt,
+                       std::optional<uint32_t> pid = std::nullopt,
+                       std::optional<uint32_t> uid = std::nullopt) const;
 
   bool SignalIsValid(int32_t signo) const;
 
@@ -105,7 +107,7 @@ class UnixSignals {
                  llvm::StringRef description,
                  llvm::StringRef alias = llvm::StringRef());
 
-  enum SignalCodePrintOption { None, Address, Bounds };
+  enum SignalCodePrintOption { None, Address, Bounds, Sender };
 
   // Instead of calling this directly, use a ADD_SIGCODE macro to get compile
   // time checks when on the native platform.
diff --git a/lldb/source/Plugins/Process/Utility/LinuxSignals.cpp 
b/lldb/source/Plugins/Process/Utility/LinuxSignals.cpp
index 9c4fe55147a28..25d4e4609bbb8 100644
--- a/lldb/source/Plugins/Process/Utility/LinuxSignals.cpp
+++ b/lldb/source/Plugins/Process/Utility/LinuxSignals.cpp
@@ -38,6 +38,17 @@
 #define ADD_SIGCODE(signal_name, signal_value, code_name, code_value, ...)     
\
   AddSignalCode(signal_value, code_value, __VA_ARGS__)
 #endif /* if defined(__linux__) && !defined(__mips__) */
+// See siginfo.h in the Linux Kernel, these codes can be sent for any signal.
+#define ADD_LINUX_SIGNAL(signo, name, ...) \
+  AddSignal(signo, name, __VA_ARGS__); \
+  ADD_SIGCODE(signo, signo, SI_QUEUE, -1, "sent by sigqueue"); \
+  ADD_SIGCODE(signo, signo, SI_TIMER, -2, "sent by timer expiration"); \
+  ADD_SIGCODE(signo, signo, SI_MESGQ, -3, "sent by real time mesq state 
change"); \
+  ADD_SIGCODE(signo, signo, SI_ASYNCIO, -4, "sent by AIO completion"); \
+  ADD_SIGCODE(signo, signo, SI_SIGIO, -5, "sent by queued SIGIO"); \
+  ADD_SIGCODE(signo, signo, SI_TKILL, -6, "sent by tkill system call"); \
+  ADD_SIGCODE(signo, signo, SI_DETHREAD, -7, "sent by execve() killing 
subsidiary threads"); \
+  ADD_SIGCODE(signo, signo, SI_ASYNCNL, -60, "sent by glibc async name lookup 
completion"); 
 
 using namespace lldb_private;
 
@@ -46,9 +57,9 @@ LinuxSignals::LinuxSignals() : UnixSignals() { Reset(); }
 void LinuxSignals::Reset() {
   m_signals.clear();
   // clang-format off
-  //        SIGNO   NAME            SUPPRESS  STOP    NOTIFY  DESCRIPTION
-  //        ======  ==============  ========  ======  ======  
===================================================
-  AddSignal(1,      "SIGHUP",       false,    true,   true,   "hangup");
+  //               SIGNO   NAME            SUPPRESS  STOP    NOTIFY  
DESCRIPTION
+  //               ======  ==============  ========  ======  ======  
===================================================
+  ADD_LINUX_SIGNAL(1,      "SIGHUP",       false,    true,   true,   "hangup");
   AddSignal(2,      "SIGINT",       true,     true,   true,   "interrupt");
   AddSignal(3,      "SIGQUIT",      false,    true,   true,   "quit");
 
diff --git a/lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp 
b/lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp
index a0cd0ee5025bd..267879a473463 100644
--- a/lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp
+++ b/lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp
@@ -584,9 +584,13 @@ Status ELFLinuxSigInfo::Parse(const DataExtractor &data, 
const ArchSpec &arch,
   // 64b ELF have a 4 byte pad.
   if (data.GetAddressByteSize() == 8)
     offset += 4;
-  // Not every stop signal has a valid address, but that will get resolved in
-  // the unix_signals.GetSignalDescription() call below.
-  if (unix_signals.GetShouldStop(si_signo)) {
+
+ if (si_code < 0) {
+  sigfault.kill._pid = data.GetU32(&offset);
+  sigfault.kill._uid = data.GetU32(&offset);
+ } else if (unix_signals.GetShouldStop(si_signo)) {
+    // Not every stop signal has a valid address, but that will get resolved in
+    // the unix_signals.GetSignalDescription() call below.
     // Instead of memcpy we call all these individually as the extractor will
     // handle endianness for us.
     sigfault.si_addr = data.GetAddress(&offset);
diff --git a/lldb/source/Plugins/Process/elf-core/ThreadElfCore.h 
b/lldb/source/Plugins/Process/elf-core/ThreadElfCore.h
index 6f8d41351a6bf..2cbf794c2b5b1 100644
--- a/lldb/source/Plugins/Process/elf-core/ThreadElfCore.h
+++ b/lldb/source/Plugins/Process/elf-core/ThreadElfCore.h
@@ -96,6 +96,12 @@ struct ELFLinuxSigInfo {
       /* used when si_code=SEGV_PKUERR */
       uint32_t _pkey;
     } bounds;
+
+    // We need this for all the generic signals.
+    struct {
+      uint32_t _pid;   /* sender's pid */
+      uint32_t _uid;   /* sender's uid */
+    } _kill;
   } sigfault;
 
   enum SigInfoNoteType : uint8_t { eUnspecified, eNT_SIGINFO };
diff --git a/lldb/source/Target/UnixSignals.cpp 
b/lldb/source/Target/UnixSignals.cpp
index da661003925c7..a5dbfd029410a 100644
--- a/lldb/source/Target/UnixSignals.cpp
+++ b/lldb/source/Target/UnixSignals.cpp
@@ -141,7 +141,9 @@ std::string
 UnixSignals::GetSignalDescription(int32_t signo, std::optional<int32_t> code,
                                   std::optional<lldb::addr_t> addr,
                                   std::optional<lldb::addr_t> lower,
-                                  std::optional<lldb::addr_t> upper) const {
+                                  std::optional<lldb::addr_t> upper,
+                                  std::optional<uint32_t> pid,
+                                  std::optional<uint32_t> uid) const {
   std::string str;
 
   collection::const_iterator pos = m_signals.find(signo);
@@ -180,6 +182,10 @@ UnixSignals::GetSignalDescription(int32_t signo, 
std::optional<int32_t> code,
             strm << sc.m_description.str();
 
           break;
+        case SignalCodePrintOption::Sender:
+          if (pid && uid)
+            strm << " (sender pid=" << *pid << ", uid=" << *uid << ")";
+          break;
         }
         str += strm.str();
       }
@@ -397,4 +403,3 @@ bool UnixSignals::ResetSignal(int32_t signo, bool 
reset_stop,
     (*elem).second.Reset(reset_stop, reset_notify, reset_suppress);
     return true;
 }
-

>From 6d8a30cc38816f661cd3126613987ccbde39ab05 Mon Sep 17 00:00:00 2001
From: Jacob Lalonde <jalalo...@fb.com>
Date: Thu, 15 May 2025 14:33:15 -0700
Subject: [PATCH 2/4] Add sender option to LinuxSignals.cpp

---
 .../Plugins/Process/Utility/LinuxSignals.cpp  | 142 +++++++++---------
 .../Process/elf-core/ThreadElfCore.cpp        |  32 ++--
 .../Plugins/Process/elf-core/ThreadElfCore.h  |  44 +++---
 3 files changed, 111 insertions(+), 107 deletions(-)

diff --git a/lldb/source/Plugins/Process/Utility/LinuxSignals.cpp 
b/lldb/source/Plugins/Process/Utility/LinuxSignals.cpp
index 25d4e4609bbb8..da0abf5a1f471 100644
--- a/lldb/source/Plugins/Process/Utility/LinuxSignals.cpp
+++ b/lldb/source/Plugins/Process/Utility/LinuxSignals.cpp
@@ -41,14 +41,14 @@
 // See siginfo.h in the Linux Kernel, these codes can be sent for any signal.
 #define ADD_LINUX_SIGNAL(signo, name, ...) \
   AddSignal(signo, name, __VA_ARGS__); \
-  ADD_SIGCODE(signo, signo, SI_QUEUE, -1, "sent by sigqueue"); \
-  ADD_SIGCODE(signo, signo, SI_TIMER, -2, "sent by timer expiration"); \
-  ADD_SIGCODE(signo, signo, SI_MESGQ, -3, "sent by real time mesq state 
change"); \
-  ADD_SIGCODE(signo, signo, SI_ASYNCIO, -4, "sent by AIO completion"); \
-  ADD_SIGCODE(signo, signo, SI_SIGIO, -5, "sent by queued SIGIO"); \
-  ADD_SIGCODE(signo, signo, SI_TKILL, -6, "sent by tkill system call"); \
-  ADD_SIGCODE(signo, signo, SI_DETHREAD, -7, "sent by execve() killing 
subsidiary threads"); \
-  ADD_SIGCODE(signo, signo, SI_ASYNCNL, -60, "sent by glibc async name lookup 
completion"); 
+  ADD_SIGCODE(signo, signo, SI_QUEUE, -1, "sent by sigqueue", 
SignalCodePrintOption::Sender); \
+  ADD_SIGCODE(signo, signo, SI_TIMER, -2, "sent by timer expiration", 
SignalCodePrintOption::Sender); \
+  ADD_SIGCODE(signo, signo, SI_MESGQ, -3, "sent by real time mesq state 
change", SignalCodePrintOption::Sender); \
+  ADD_SIGCODE(signo, signo, SI_ASYNCIO, -4, "sent by AIO completion", 
SignalCodePrintOption::Sender); \
+  ADD_SIGCODE(signo, signo, SI_SIGIO, -5, "sent by queued SIGIO", 
SignalCodePrintOption::Sender); \
+  ADD_SIGCODE(signo, signo, SI_TKILL, -6, "sent by tkill system call", 
SignalCodePrintOption::Sender); \
+  ADD_SIGCODE(signo, signo, SI_DETHREAD, -7, "sent by execve() killing 
subsidiary threads", SignalCodePrintOption::Sender); \
+  ADD_SIGCODE(signo, signo, SI_ASYNCNL, -60, "sent by glibc async name lookup 
completion", SignalCodePrintOption::Sender); 
 
 using namespace lldb_private;
 
@@ -60,10 +60,10 @@ void LinuxSignals::Reset() {
   //               SIGNO   NAME            SUPPRESS  STOP    NOTIFY  
DESCRIPTION
   //               ======  ==============  ========  ======  ======  
===================================================
   ADD_LINUX_SIGNAL(1,      "SIGHUP",       false,    true,   true,   "hangup");
-  AddSignal(2,      "SIGINT",       true,     true,   true,   "interrupt");
-  AddSignal(3,      "SIGQUIT",      false,    true,   true,   "quit");
+  ADD_LINUX_SIGNAL(2,      "SIGINT",       true,     true,   true,   
"interrupt");
+  ADD_LINUX_SIGNAL(3,      "SIGQUIT",      false,    true,   true,   "quit");
 
-  AddSignal(4,      "SIGILL",       false,    true,   true,   "illegal 
instruction");
+  ADD_LINUX_SIGNAL(4,      "SIGILL",       false,    true,   true,   "illegal 
instruction");
   ADD_SIGCODE(SIGILL, 4, ILL_ILLOPC, 1, "illegal opcode");
   ADD_SIGCODE(SIGILL, 4, ILL_ILLOPN, 2, "illegal operand");
   ADD_SIGCODE(SIGILL, 4, ILL_ILLADR, 3, "illegal addressing mode");
@@ -73,15 +73,15 @@ void LinuxSignals::Reset() {
   ADD_SIGCODE(SIGILL, 4, ILL_COPROC, 7, "coprocessor error");
   ADD_SIGCODE(SIGILL, 4, ILL_BADSTK, 8, "internal stack error");
 
-  AddSignal(5,      "SIGTRAP",      true,     true,   true,   "trace trap (not 
reset when caught)");
-  AddSignal(6,      "SIGABRT",      false,    true,   true,   "abort()/IOT 
trap", "SIGIOT");
+  ADD_LINUX_SIGNAL(5,      "SIGTRAP",      true,     true,   true,   "trace 
trap (not reset when caught)");
+  ADD_LINUX_SIGNAL(6,      "SIGABRT",      false,    true,   true,   
"abort()/IOT trap", "SIGIOT");
 
-  AddSignal(7,      "SIGBUS",       false,    true,   true,   "bus error");
+  ADD_LINUX_SIGNAL(7,      "SIGBUS",       false,    true,   true,   "bus 
error");
   ADD_SIGCODE(SIGBUS, 7, BUS_ADRALN, 1, "illegal alignment");
   ADD_SIGCODE(SIGBUS, 7, BUS_ADRERR, 2, "illegal address");
   ADD_SIGCODE(SIGBUS, 7, BUS_OBJERR, 3, "hardware error");
 
-  AddSignal(8,      "SIGFPE",       false,    true,   true,   "floating point 
exception");
+  ADD_LINUX_SIGNAL(8,      "SIGFPE",       false,    true,   true,   "floating 
point exception");
   ADD_SIGCODE(SIGFPE, 8, FPE_INTDIV, 1, "integer divide by zero");
   ADD_SIGCODE(SIGFPE, 8, FPE_INTOVF, 2, "integer overflow");
   ADD_SIGCODE(SIGFPE, 8, FPE_FLTDIV, 3, "floating point divide by zero");
@@ -91,10 +91,10 @@ void LinuxSignals::Reset() {
   ADD_SIGCODE(SIGFPE, 8, FPE_FLTINV, 7, "floating point invalid operation");
   ADD_SIGCODE(SIGFPE, 8, FPE_FLTSUB, 8, "subscript out of range");
 
-  AddSignal(9,      "SIGKILL",      false,    true,   true,   "kill");
-  AddSignal(10,     "SIGUSR1",      false,    true,   true,   "user defined 
signal 1");
+  ADD_LINUX_SIGNAL(9,      "SIGKILL",      false,    true,   true,   "kill");
+  ADD_LINUX_SIGNAL(10,     "SIGUSR1",      false,    true,   true,   "user 
defined signal 1");
 
-  AddSignal(11,     "SIGSEGV",      false,    true,   true,   "segmentation 
violation");
+  ADD_LINUX_SIGNAL(11,     "SIGSEGV",      false,    true,   true,   
"segmentation violation");
   ADD_SIGCODE(SIGSEGV, 11, SEGV_MAPERR,  1, "address not mapped to object", 
SignalCodePrintOption::Address);
   ADD_SIGCODE(SIGSEGV, 11, SEGV_ACCERR,  2, "invalid permissions for mapped 
object", SignalCodePrintOption::Address);
   ADD_SIGCODE(SIGSEGV, 11, SEGV_BNDERR,  3, "failed address bounds checks", 
SignalCodePrintOption::Bounds);
@@ -105,58 +105,58 @@ void LinuxSignals::Reset() {
   // codes. One way to get this is via unaligned SIMD loads. Treat it as 
invalid address.
   ADD_SIGCODE(SIGSEGV, 11, SI_KERNEL, 0x80, "invalid address", 
SignalCodePrintOption::Address);
 
-  AddSignal(12,     "SIGUSR2",      false,    true,   true,   "user defined 
signal 2");
-  AddSignal(13,     "SIGPIPE",      false,    true,   true,   "write to pipe 
with reading end closed");
-  AddSignal(14,     "SIGALRM",      false,    false,  false,  "alarm");
-  AddSignal(15,     "SIGTERM",      false,    true,   true,   "termination 
requested");
-  AddSignal(16,     "SIGSTKFLT",    false,    true,   true,   "stack fault");
-  AddSignal(17,     "SIGCHLD",      false,    false,  true,   "child status 
has changed", "SIGCLD");
-  AddSignal(18,     "SIGCONT",      false,    false,  true,   "process 
continue");
-  AddSignal(19,     "SIGSTOP",      true,     true,   true,   "process stop");
-  AddSignal(20,     "SIGTSTP",      false,    true,   true,   "tty stop");
-  AddSignal(21,     "SIGTTIN",      false,    true,   true,   "background tty 
read");
-  AddSignal(22,     "SIGTTOU",      false,    true,   true,   "background tty 
write");
-  AddSignal(23,     "SIGURG",       false,    true,   true,   "urgent data on 
socket");
-  AddSignal(24,     "SIGXCPU",      false,    true,   true,   "CPU resource 
exceeded");
-  AddSignal(25,     "SIGXFSZ",      false,    true,   true,   "file size limit 
exceeded");
-  AddSignal(26,     "SIGVTALRM",    false,    true,   true,   "virtual time 
alarm");
-  AddSignal(27,     "SIGPROF",      false,    false,  false,  "profiling time 
alarm");
-  AddSignal(28,     "SIGWINCH",     false,    true,   true,   "window size 
changes");
-  AddSignal(29,     "SIGIO",        false,    true,   true,   "input/output 
ready/Pollable event", "SIGPOLL");
-  AddSignal(30,     "SIGPWR",       false,    true,   true,   "power failure");
-  AddSignal(31,     "SIGSYS",       false,    true,   true,   "invalid system 
call");
-  AddSignal(32,     "SIG32",        false,    false,  false,  "threading 
library internal signal 1");
-  AddSignal(33,     "SIG33",        false,    false,  false,  "threading 
library internal signal 2");
-  AddSignal(34,     "SIGRTMIN",     false,    false,  false,  "real time 
signal 0");
-  AddSignal(35,     "SIGRTMIN+1",   false,    false,  false,  "real time 
signal 1");
-  AddSignal(36,     "SIGRTMIN+2",   false,    false,  false,  "real time 
signal 2");
-  AddSignal(37,     "SIGRTMIN+3",   false,    false,  false,  "real time 
signal 3");
-  AddSignal(38,     "SIGRTMIN+4",   false,    false,  false,  "real time 
signal 4");
-  AddSignal(39,     "SIGRTMIN+5",   false,    false,  false,  "real time 
signal 5");
-  AddSignal(40,     "SIGRTMIN+6",   false,    false,  false,  "real time 
signal 6");
-  AddSignal(41,     "SIGRTMIN+7",   false,    false,  false,  "real time 
signal 7");
-  AddSignal(42,     "SIGRTMIN+8",   false,    false,  false,  "real time 
signal 8");
-  AddSignal(43,     "SIGRTMIN+9",   false,    false,  false,  "real time 
signal 9");
-  AddSignal(44,     "SIGRTMIN+10",  false,    false,  false,  "real time 
signal 10");
-  AddSignal(45,     "SIGRTMIN+11",  false,    false,  false,  "real time 
signal 11");
-  AddSignal(46,     "SIGRTMIN+12",  false,    false,  false,  "real time 
signal 12");
-  AddSignal(47,     "SIGRTMIN+13",  false,    false,  false,  "real time 
signal 13");
-  AddSignal(48,     "SIGRTMIN+14",  false,    false,  false,  "real time 
signal 14");
-  AddSignal(49,     "SIGRTMIN+15",  false,    false,  false,  "real time 
signal 15");
-  AddSignal(50,     "SIGRTMAX-14",  false,    false,  false,  "real time 
signal 16"); // switching to SIGRTMAX-xxx to match "kill -l" output
-  AddSignal(51,     "SIGRTMAX-13",  false,    false,  false,  "real time 
signal 17");
-  AddSignal(52,     "SIGRTMAX-12",  false,    false,  false,  "real time 
signal 18");
-  AddSignal(53,     "SIGRTMAX-11",  false,    false,  false,  "real time 
signal 19");
-  AddSignal(54,     "SIGRTMAX-10",  false,    false,  false,  "real time 
signal 20");
-  AddSignal(55,     "SIGRTMAX-9",   false,    false,  false,  "real time 
signal 21");
-  AddSignal(56,     "SIGRTMAX-8",   false,    false,  false,  "real time 
signal 22");
-  AddSignal(57,     "SIGRTMAX-7",   false,    false,  false,  "real time 
signal 23");
-  AddSignal(58,     "SIGRTMAX-6",   false,    false,  false,  "real time 
signal 24");
-  AddSignal(59,     "SIGRTMAX-5",   false,    false,  false,  "real time 
signal 25");
-  AddSignal(60,     "SIGRTMAX-4",   false,    false,  false,  "real time 
signal 26");
-  AddSignal(61,     "SIGRTMAX-3",   false,    false,  false,  "real time 
signal 27");
-  AddSignal(62,     "SIGRTMAX-2",   false,    false,  false,  "real time 
signal 28");
-  AddSignal(63,     "SIGRTMAX-1",   false,    false,  false,  "real time 
signal 29");
-  AddSignal(64,     "SIGRTMAX",     false,    false,  false,  "real time 
signal 30");
+  ADD_LINUX_SIGNAL(12,     "SIGUSR2",      false,    true,   true,   "user 
defined signal 2");
+  ADD_LINUX_SIGNAL(13,     "SIGPIPE",      false,    true,   true,   "write to 
pipe with reading end closed");
+  ADD_LINUX_SIGNAL(14,     "SIGALRM",      false,    false,  false,  "alarm");
+  ADD_LINUX_SIGNAL(15,     "SIGTERM",      false,    true,   true,   
"termination requested");
+  ADD_LINUX_SIGNAL(16,     "SIGSTKFLT",    false,    true,   true,   "stack 
fault");
+  ADD_LINUX_SIGNAL(17,     "SIGCHLD",      false,    false,  true,   "child 
status has changed", "SIGCLD");
+  ADD_LINUX_SIGNAL(18,     "SIGCONT",      false,    false,  true,   "process 
continue");
+  ADD_LINUX_SIGNAL(19,     "SIGSTOP",      true,     true,   true,   "process 
stop");
+  ADD_LINUX_SIGNAL(20,     "SIGTSTP",      false,    true,   true,   "tty 
stop");
+  ADD_LINUX_SIGNAL(21,     "SIGTTIN",      false,    true,   true,   
"background tty read");
+  ADD_LINUX_SIGNAL(22,     "SIGTTOU",      false,    true,   true,   
"background tty write");
+  ADD_LINUX_SIGNAL(23,     "SIGURG",       false,    true,   true,   "urgent 
data on socket");
+  ADD_LINUX_SIGNAL(24,     "SIGXCPU",      false,    true,   true,   "CPU 
resource exceeded");
+  ADD_LINUX_SIGNAL(25,     "SIGXFSZ",      false,    true,   true,   "file 
size limit exceeded");
+  ADD_LINUX_SIGNAL(26,     "SIGVTALRM",    false,    true,   true,   "virtual 
time alarm");
+  ADD_LINUX_SIGNAL(27,     "SIGPROF",      false,    false,  false,  
"profiling time alarm");
+  ADD_LINUX_SIGNAL(28,     "SIGWINCH",     false,    true,   true,   "window 
size changes");
+  ADD_LINUX_SIGNAL(29,     "SIGIO",        false,    true,   true,   
"input/output ready/Pollable event", "SIGPOLL");
+  ADD_LINUX_SIGNAL(30,     "SIGPWR",       false,    true,   true,   "power 
failure");
+  ADD_LINUX_SIGNAL(31,     "SIGSYS",       false,    true,   true,   "invalid 
system call");
+  ADD_LINUX_SIGNAL(32,     "SIG32",        false,    false,  false,  
"threading library internal signal 1");
+  ADD_LINUX_SIGNAL(33,     "SIG33",        false,    false,  false,  
"threading library internal signal 2");
+  ADD_LINUX_SIGNAL(34,     "SIGRTMIN",     false,    false,  false,  "real 
time signal 0");
+  ADD_LINUX_SIGNAL(35,     "SIGRTMIN+1",   false,    false,  false,  "real 
time signal 1");
+  ADD_LINUX_SIGNAL(36,     "SIGRTMIN+2",   false,    false,  false,  "real 
time signal 2");
+  ADD_LINUX_SIGNAL(37,     "SIGRTMIN+3",   false,    false,  false,  "real 
time signal 3");
+  ADD_LINUX_SIGNAL(38,     "SIGRTMIN+4",   false,    false,  false,  "real 
time signal 4");
+  ADD_LINUX_SIGNAL(39,     "SIGRTMIN+5",   false,    false,  false,  "real 
time signal 5");
+  ADD_LINUX_SIGNAL(40,     "SIGRTMIN+6",   false,    false,  false,  "real 
time signal 6");
+  ADD_LINUX_SIGNAL(41,     "SIGRTMIN+7",   false,    false,  false,  "real 
time signal 7");
+  ADD_LINUX_SIGNAL(42,     "SIGRTMIN+8",   false,    false,  false,  "real 
time signal 8");
+  ADD_LINUX_SIGNAL(43,     "SIGRTMIN+9",   false,    false,  false,  "real 
time signal 9");
+  ADD_LINUX_SIGNAL(44,     "SIGRTMIN+10",  false,    false,  false,  "real 
time signal 10");
+  ADD_LINUX_SIGNAL(45,     "SIGRTMIN+11",  false,    false,  false,  "real 
time signal 11");
+  ADD_LINUX_SIGNAL(46,     "SIGRTMIN+12",  false,    false,  false,  "real 
time signal 12");
+  ADD_LINUX_SIGNAL(47,     "SIGRTMIN+13",  false,    false,  false,  "real 
time signal 13");
+  ADD_LINUX_SIGNAL(48,     "SIGRTMIN+14",  false,    false,  false,  "real 
time signal 14");
+  ADD_LINUX_SIGNAL(49,     "SIGRTMIN+15",  false,    false,  false,  "real 
time signal 15");
+  ADD_LINUX_SIGNAL(50,     "SIGRTMAX-14",  false,    false,  false,  "real 
time signal 16"); // switching to SIGRTMAX-xxx to match "kill -l" output
+  ADD_LINUX_SIGNAL(51,     "SIGRTMAX-13",  false,    false,  false,  "real 
time signal 17");
+  ADD_LINUX_SIGNAL(52,     "SIGRTMAX-12",  false,    false,  false,  "real 
time signal 18");
+  ADD_LINUX_SIGNAL(53,     "SIGRTMAX-11",  false,    false,  false,  "real 
time signal 19");
+  ADD_LINUX_SIGNAL(54,     "SIGRTMAX-10",  false,    false,  false,  "real 
time signal 20");
+  ADD_LINUX_SIGNAL(55,     "SIGRTMAX-9",   false,    false,  false,  "real 
time signal 21");
+  ADD_LINUX_SIGNAL(56,     "SIGRTMAX-8",   false,    false,  false,  "real 
time signal 22");
+  ADD_LINUX_SIGNAL(57,     "SIGRTMAX-7",   false,    false,  false,  "real 
time signal 23");
+  ADD_LINUX_SIGNAL(58,     "SIGRTMAX-6",   false,    false,  false,  "real 
time signal 24");
+  ADD_LINUX_SIGNAL(59,     "SIGRTMAX-5",   false,    false,  false,  "real 
time signal 25");
+  ADD_LINUX_SIGNAL(60,     "SIGRTMAX-4",   false,    false,  false,  "real 
time signal 26");
+  ADD_LINUX_SIGNAL(61,     "SIGRTMAX-3",   false,    false,  false,  "real 
time signal 27");
+  ADD_LINUX_SIGNAL(62,     "SIGRTMAX-2",   false,    false,  false,  "real 
time signal 28");
+  ADD_LINUX_SIGNAL(63,     "SIGRTMAX-1",   false,    false,  false,  "real 
time signal 29");
+  ADD_LINUX_SIGNAL(64,     "SIGRTMAX",     false,    false,  false,  "real 
time signal 30");
   // clang-format on
 }
diff --git a/lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp 
b/lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp
index 267879a473463..ce0f65cd9f14c 100644
--- a/lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp
+++ b/lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp
@@ -586,24 +586,24 @@ Status ELFLinuxSigInfo::Parse(const DataExtractor &data, 
const ArchSpec &arch,
     offset += 4;
 
  if (si_code < 0) {
-  sigfault.kill._pid = data.GetU32(&offset);
-  sigfault.kill._uid = data.GetU32(&offset);
+  sifields.kill.pid = data.GetU32(&offset);
+  sifields.kill.uid = data.GetU32(&offset);
  } else if (unix_signals.GetShouldStop(si_signo)) {
     // Not every stop signal has a valid address, but that will get resolved in
     // the unix_signals.GetSignalDescription() call below.
     // Instead of memcpy we call all these individually as the extractor will
     // handle endianness for us.
-    sigfault.si_addr = data.GetAddress(&offset);
-    sigfault.si_addr_lsb = data.GetU16(&offset);
-    if (data.GetByteSize() - offset >= sizeof(sigfault.bounds)) {
-      sigfault.bounds._addr_bnd._lower = data.GetAddress(&offset);
-      sigfault.bounds._addr_bnd._upper = data.GetAddress(&offset);
-      sigfault.bounds._pkey = data.GetU32(&offset);
+    sifields.sigfault.si_addr = data.GetAddress(&offset);
+    sifields.sigfault.si_addr_lsb = data.GetU16(&offset);
+    if (data.GetByteSize() - offset >= sizeof(sifields.sigfault.bounds)) {
+      sifields.sigfault.bounds._addr_bnd._lower = data.GetAddress(&offset);
+      sifields.sigfault.bounds._addr_bnd._upper = data.GetAddress(&offset);
+      sifields.sigfault.bounds._pkey = data.GetU32(&offset);
     } else {
       // Set these to 0 so we don't use bogus data for the description.
-      sigfault.bounds._addr_bnd._lower = 0;
-      sigfault.bounds._addr_bnd._upper = 0;
-      sigfault.bounds._pkey = 0;
+      sifields.sigfault.bounds._addr_bnd._lower = 0;
+      sifields.sigfault.bounds._addr_bnd._upper = 0;
+      sifields.sigfault.bounds._pkey = 0;
     }
   }
 
@@ -613,13 +613,15 @@ Status ELFLinuxSigInfo::Parse(const DataExtractor &data, 
const ArchSpec &arch,
 std::string ELFLinuxSigInfo::GetDescription(
     const lldb_private::UnixSignals &unix_signals) const {
   if (unix_signals.GetShouldStop(si_signo) && note_type == eNT_SIGINFO) {
-    if (sigfault.bounds._addr_bnd._upper != 0)
+    if (si_code < 0)
+      return unix_signals.GetSignalDescription(si_signo, si_code, 
std::nullopt, std::nullopt, std::nullopt, sifields.kill.pid, sifields.kill.uid);
+    else if (sifields.sigfault.bounds._addr_bnd._upper != 0)
       return unix_signals.GetSignalDescription(
-          si_signo, si_code, sigfault.si_addr, 
sigfault.bounds._addr_bnd._lower,
-          sigfault.bounds._addr_bnd._upper);
+          si_signo, si_code, sifields.sigfault.si_addr, 
sifields.sigfault.bounds._addr_bnd._lower,
+          sifields.sigfault.bounds._addr_bnd._upper);
     else
       return unix_signals.GetSignalDescription(si_signo, si_code,
-                                               sigfault.si_addr);
+        sifields.sigfault.si_addr);
   }
 
   // This looks weird, but there is an existing pattern where we don't pass a
diff --git a/lldb/source/Plugins/Process/elf-core/ThreadElfCore.h 
b/lldb/source/Plugins/Process/elf-core/ThreadElfCore.h
index 2cbf794c2b5b1..2c254b4b522e9 100644
--- a/lldb/source/Plugins/Process/elf-core/ThreadElfCore.h
+++ b/lldb/source/Plugins/Process/elf-core/ThreadElfCore.h
@@ -82,27 +82,29 @@ struct ELFLinuxSigInfo {
   int32_t si_signo; // Order matters for the first 3.
   int32_t si_errno;
   int32_t si_code;
-  // Copied from siginfo_t so we don't have to include signal.h on non 'Nix
-  // builds. Slight modifications to ensure no 32b vs 64b differences.
-  struct alignas(8) {
-    lldb::addr_t si_addr; /* faulting insn/memory ref. */
-    int16_t si_addr_lsb;  /* Valid LSB of the reported address.  */
-    union {
-      /* used when si_code=SEGV_BNDERR */
-      struct {
-        lldb::addr_t _lower;
-        lldb::addr_t _upper;
-      } _addr_bnd;
-      /* used when si_code=SEGV_PKUERR */
-      uint32_t _pkey;
-    } bounds;
-
-    // We need this for all the generic signals.
-    struct {
-      uint32_t _pid;   /* sender's pid */
-      uint32_t _uid;   /* sender's uid */
-    } _kill;
-  } sigfault;
+  union alignas(8) {
+    struct alignas(8) {
+      uint32_t pid;    /* sender's pid */
+      uint32_t uid;    /* sender's uid */
+    } kill;
+    // Copied from siginfo_t so we don't have to include signal.h on non 'Nix
+    // builds. Slight modifications to ensure no 32b vs 64b differences.
+    struct alignas(8) {
+      lldb::addr_t si_addr; /* faulting insn/memory ref. */
+      int16_t si_addr_lsb;  /* Valid LSB of the reported address.  */
+      union {
+        /* used when si_code=SEGV_BNDERR */
+        struct {
+          lldb::addr_t _lower;
+          lldb::addr_t _upper;
+        } _addr_bnd;
+        /* used when si_code=SEGV_PKUERR */
+        uint32_t _pkey;
+      } bounds;
+
+      // We need this for all the generic signals.
+    } sigfault;
+  } sifields;
 
   enum SigInfoNoteType : uint8_t { eUnspecified, eNT_SIGINFO };
   SigInfoNoteType note_type;

>From 9e352e71666628c7e81f520e8619779cc7a6e150 Mon Sep 17 00:00:00 2001
From: Jacob Lalonde <jalalo...@fb.com>
Date: Thu, 15 May 2025 14:46:40 -0700
Subject: [PATCH 3/4] Add test for sender case

---
 lldb/unittests/Signals/UnixSignalsTest.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lldb/unittests/Signals/UnixSignalsTest.cpp 
b/lldb/unittests/Signals/UnixSignalsTest.cpp
index 9a7d9afc2b185..825cc5ea6a782 100644
--- a/lldb/unittests/Signals/UnixSignalsTest.cpp
+++ b/lldb/unittests/Signals/UnixSignalsTest.cpp
@@ -27,6 +27,7 @@ class TestSignals : public UnixSignals {
     AddSignalCode(16, 2, "SIG16 with a fault address",
                   SignalCodePrintOption::Address);
     AddSignalCode(16, 3, "bounds violation", SignalCodePrintOption::Bounds);
+    AddSignalCode(16, -6, "sent by tkill system call", 
SignalCodePrintOption::Sender);
   }
 };
 
@@ -124,6 +125,10 @@ TEST(UnixSignalsTest, GetAsString) {
   // No address given just print the code description.
   ASSERT_EQ("SIG16: SIG16 with a fault address",
             signals.GetSignalDescription(16, 2));
+  // TKill, but with no sender
+  ASSERT_EQ("SIG16: sent by tkill system call", 
signals.GetSignalDescription(16, -6, 0xCAFEF00D));
+  // TKill, but with no sender
+  ASSERT_EQ("SIG16: sent by tkill system call (sender pid=912, uid=99)", 
signals.GetSignalDescription(16, -6, 0xCAFEF00D, std::nullopt, std::nullopt, 
912, 99));
 
   const char *expected = "SIG16: bounds violation";
   // Must pass all needed info to get full output.

>From 1a1b9fa48bead59a15291a58814e363cd4412f55 Mon Sep 17 00:00:00 2001
From: Jacob Lalonde <jalalo...@fb.com>
Date: Thu, 15 May 2025 15:03:32 -0700
Subject: [PATCH 4/4] run GCF

---
 .../Plugins/Process/Utility/LinuxSignals.cpp  | 31 +++++++++++++------
 .../Process/elf-core/ThreadElfCore.cpp        | 17 +++++-----
 .../Plugins/Process/elf-core/ThreadElfCore.h  |  4 +--
 lldb/source/Target/UnixSignals.cpp            | 12 +++----
 lldb/unittests/Signals/UnixSignalsTest.cpp    | 10 ++++--
 5 files changed, 45 insertions(+), 29 deletions(-)

diff --git a/lldb/source/Plugins/Process/Utility/LinuxSignals.cpp 
b/lldb/source/Plugins/Process/Utility/LinuxSignals.cpp
index da0abf5a1f471..76c32e376eb4b 100644
--- a/lldb/source/Plugins/Process/Utility/LinuxSignals.cpp
+++ b/lldb/source/Plugins/Process/Utility/LinuxSignals.cpp
@@ -39,16 +39,27 @@
   AddSignalCode(signal_value, code_value, __VA_ARGS__)
 #endif /* if defined(__linux__) && !defined(__mips__) */
 // See siginfo.h in the Linux Kernel, these codes can be sent for any signal.
-#define ADD_LINUX_SIGNAL(signo, name, ...) \
-  AddSignal(signo, name, __VA_ARGS__); \
-  ADD_SIGCODE(signo, signo, SI_QUEUE, -1, "sent by sigqueue", 
SignalCodePrintOption::Sender); \
-  ADD_SIGCODE(signo, signo, SI_TIMER, -2, "sent by timer expiration", 
SignalCodePrintOption::Sender); \
-  ADD_SIGCODE(signo, signo, SI_MESGQ, -3, "sent by real time mesq state 
change", SignalCodePrintOption::Sender); \
-  ADD_SIGCODE(signo, signo, SI_ASYNCIO, -4, "sent by AIO completion", 
SignalCodePrintOption::Sender); \
-  ADD_SIGCODE(signo, signo, SI_SIGIO, -5, "sent by queued SIGIO", 
SignalCodePrintOption::Sender); \
-  ADD_SIGCODE(signo, signo, SI_TKILL, -6, "sent by tkill system call", 
SignalCodePrintOption::Sender); \
-  ADD_SIGCODE(signo, signo, SI_DETHREAD, -7, "sent by execve() killing 
subsidiary threads", SignalCodePrintOption::Sender); \
-  ADD_SIGCODE(signo, signo, SI_ASYNCNL, -60, "sent by glibc async name lookup 
completion", SignalCodePrintOption::Sender); 
+#define ADD_LINUX_SIGNAL(signo, name, ...)                                     
\
+  AddSignal(signo, name, __VA_ARGS__);                                         
\
+  ADD_SIGCODE(signo, signo, SI_QUEUE, -1, "sent by sigqueue",                  
\
+              SignalCodePrintOption::Sender);                                  
\
+  ADD_SIGCODE(signo, signo, SI_TIMER, -2, "sent by timer expiration",          
\
+              SignalCodePrintOption::Sender);                                  
\
+  ADD_SIGCODE(signo, signo, SI_MESGQ, -3,                                      
\
+              "sent by real time mesq state change",                           
\
+              SignalCodePrintOption::Sender);                                  
\
+  ADD_SIGCODE(signo, signo, SI_ASYNCIO, -4, "sent by AIO completion",          
\
+              SignalCodePrintOption::Sender);                                  
\
+  ADD_SIGCODE(signo, signo, SI_SIGIO, -5, "sent by queued SIGIO",              
\
+              SignalCodePrintOption::Sender);                                  
\
+  ADD_SIGCODE(signo, signo, SI_TKILL, -6, "sent by tkill system call",         
\
+              SignalCodePrintOption::Sender);                                  
\
+  ADD_SIGCODE(signo, signo, SI_DETHREAD, -7,                                   
\
+              "sent by execve() killing subsidiary threads",                   
\
+              SignalCodePrintOption::Sender);                                  
\
+  ADD_SIGCODE(signo, signo, SI_ASYNCNL, -60,                                   
\
+              "sent by glibc async name lookup completion",                    
\
+              SignalCodePrintOption::Sender);
 
 using namespace lldb_private;
 
diff --git a/lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp 
b/lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp
index ce0f65cd9f14c..907e009bc7b80 100644
--- a/lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp
+++ b/lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp
@@ -585,10 +585,10 @@ Status ELFLinuxSigInfo::Parse(const DataExtractor &data, 
const ArchSpec &arch,
   if (data.GetAddressByteSize() == 8)
     offset += 4;
 
- if (si_code < 0) {
-  sifields.kill.pid = data.GetU32(&offset);
-  sifields.kill.uid = data.GetU32(&offset);
- } else if (unix_signals.GetShouldStop(si_signo)) {
+  if (si_code < 0) {
+    sifields.kill.pid = data.GetU32(&offset);
+    sifields.kill.uid = data.GetU32(&offset);
+  } else if (unix_signals.GetShouldStop(si_signo)) {
     // Not every stop signal has a valid address, but that will get resolved in
     // the unix_signals.GetSignalDescription() call below.
     // Instead of memcpy we call all these individually as the extractor will
@@ -614,14 +614,17 @@ std::string ELFLinuxSigInfo::GetDescription(
     const lldb_private::UnixSignals &unix_signals) const {
   if (unix_signals.GetShouldStop(si_signo) && note_type == eNT_SIGINFO) {
     if (si_code < 0)
-      return unix_signals.GetSignalDescription(si_signo, si_code, 
std::nullopt, std::nullopt, std::nullopt, sifields.kill.pid, sifields.kill.uid);
+      return unix_signals.GetSignalDescription(
+          si_signo, si_code, std::nullopt, std::nullopt, std::nullopt,
+          sifields.kill.pid, sifields.kill.uid);
     else if (sifields.sigfault.bounds._addr_bnd._upper != 0)
       return unix_signals.GetSignalDescription(
-          si_signo, si_code, sifields.sigfault.si_addr, 
sifields.sigfault.bounds._addr_bnd._lower,
+          si_signo, si_code, sifields.sigfault.si_addr,
+          sifields.sigfault.bounds._addr_bnd._lower,
           sifields.sigfault.bounds._addr_bnd._upper);
     else
       return unix_signals.GetSignalDescription(si_signo, si_code,
-        sifields.sigfault.si_addr);
+                                               sifields.sigfault.si_addr);
   }
 
   // This looks weird, but there is an existing pattern where we don't pass a
diff --git a/lldb/source/Plugins/Process/elf-core/ThreadElfCore.h 
b/lldb/source/Plugins/Process/elf-core/ThreadElfCore.h
index 2c254b4b522e9..40434543b7bb2 100644
--- a/lldb/source/Plugins/Process/elf-core/ThreadElfCore.h
+++ b/lldb/source/Plugins/Process/elf-core/ThreadElfCore.h
@@ -84,8 +84,8 @@ struct ELFLinuxSigInfo {
   int32_t si_code;
   union alignas(8) {
     struct alignas(8) {
-      uint32_t pid;    /* sender's pid */
-      uint32_t uid;    /* sender's uid */
+      uint32_t pid; /* sender's pid */
+      uint32_t uid; /* sender's uid */
     } kill;
     // Copied from siginfo_t so we don't have to include signal.h on non 'Nix
     // builds. Slight modifications to ensure no 32b vs 64b differences.
diff --git a/lldb/source/Target/UnixSignals.cpp 
b/lldb/source/Target/UnixSignals.cpp
index a5dbfd029410a..6113c6648817c 100644
--- a/lldb/source/Target/UnixSignals.cpp
+++ b/lldb/source/Target/UnixSignals.cpp
@@ -137,13 +137,11 @@ llvm::StringRef UnixSignals::GetSignalAsStringRef(int32_t 
signo) const {
   return pos->second.m_name;
 }
 
-std::string
-UnixSignals::GetSignalDescription(int32_t signo, std::optional<int32_t> code,
-                                  std::optional<lldb::addr_t> addr,
-                                  std::optional<lldb::addr_t> lower,
-                                  std::optional<lldb::addr_t> upper,
-                                  std::optional<uint32_t> pid,
-                                  std::optional<uint32_t> uid) const {
+std::string UnixSignals::GetSignalDescription(
+    int32_t signo, std::optional<int32_t> code,
+    std::optional<lldb::addr_t> addr, std::optional<lldb::addr_t> lower,
+    std::optional<lldb::addr_t> upper, std::optional<uint32_t> pid,
+    std::optional<uint32_t> uid) const {
   std::string str;
 
   collection::const_iterator pos = m_signals.find(signo);
diff --git a/lldb/unittests/Signals/UnixSignalsTest.cpp 
b/lldb/unittests/Signals/UnixSignalsTest.cpp
index 825cc5ea6a782..582e441556067 100644
--- a/lldb/unittests/Signals/UnixSignalsTest.cpp
+++ b/lldb/unittests/Signals/UnixSignalsTest.cpp
@@ -27,7 +27,8 @@ class TestSignals : public UnixSignals {
     AddSignalCode(16, 2, "SIG16 with a fault address",
                   SignalCodePrintOption::Address);
     AddSignalCode(16, 3, "bounds violation", SignalCodePrintOption::Bounds);
-    AddSignalCode(16, -6, "sent by tkill system call", 
SignalCodePrintOption::Sender);
+    AddSignalCode(16, -6, "sent by tkill system call",
+                  SignalCodePrintOption::Sender);
   }
 };
 
@@ -126,9 +127,12 @@ TEST(UnixSignalsTest, GetAsString) {
   ASSERT_EQ("SIG16: SIG16 with a fault address",
             signals.GetSignalDescription(16, 2));
   // TKill, but with no sender
-  ASSERT_EQ("SIG16: sent by tkill system call", 
signals.GetSignalDescription(16, -6, 0xCAFEF00D));
+  ASSERT_EQ("SIG16: sent by tkill system call",
+            signals.GetSignalDescription(16, -6, 0xCAFEF00D));
   // TKill, but with no sender
-  ASSERT_EQ("SIG16: sent by tkill system call (sender pid=912, uid=99)", 
signals.GetSignalDescription(16, -6, 0xCAFEF00D, std::nullopt, std::nullopt, 
912, 99));
+  ASSERT_EQ("SIG16: sent by tkill system call (sender pid=912, uid=99)",
+            signals.GetSignalDescription(16, -6, 0xCAFEF00D, std::nullopt,
+                                         std::nullopt, 912, 99));
 
   const char *expected = "SIG16: bounds violation";
   // Must pass all needed info to get full output.

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