feat: add process termination codes and SYS_ABORT; whole-process abort() from any thread in libc and montauk-rt

kernel/src/Api/BuildNo.hpp

@@ -12,4 +12,4 @@
 
 #pragma once
 
-#define MONTAUK_BUILD_NUMBER 306
+#define MONTAUK_BUILD_NUMBER 308

kernel/src/Api/Process.hpp

@@ -220,10 +220,17 @@ namespace montauk::abi {
         return count;
     }
 
+    // Flag every thread of the caller's process with TerminatedAborted, then
+    // exit this one. A sibling's ExitProcess ends only itself; the main
+    // thread and the other siblings follow via killPending.
+    static void Sys_Abort() {
+        Sched::KillProcess(Sched::GetCurrentPid(), TerminatedAborted);
+        Sched::ExitProcess();
+    }
+
     static int Sys_Kill(int pid) {
-        // A process may always kill itself: a sibling thread has no other
+        // A process may always kill itself (kill(getpid(), ...)); waiters
-        // way to take the whole process down (SYS_EXIT from a sibling ends
+        // see TerminatedKilled. abort() uses SYS_ABORT instead.
-        // only that thread), which abort()/panic=abort need.
         if (pid == Sched::GetCurrentPid()) return Sched::KillProcess(pid);
         if (!Sched::HasCapability(CAP_PROCESS_ADMIN)) {
             int ancestor = pid;

kernel/src/Api/Syscall.cpp

@@ -400,6 +400,9 @@ namespace montauk::abi {
                 return (int64_t)Sys_ProcList((ProcInfo*)frame->arg1, (int)frame->arg2);
             case SYS_KILL:
                 return (int64_t)Sys_Kill((int)frame->arg1);
+            case SYS_ABORT:
+                Sys_Abort();
+                return Success;
             case SYS_SETSESSION:
                 return (int64_t)Sys_SetSession();
             case SYS_KILLSESSION:

kernel/src/Api/Syscall.hpp

@@ -375,6 +375,11 @@ namespace montauk::abi {
     static constexpr uint64_t FUTEX_WAIT_FOREVER       = ~0ULL;
     static constexpr uint32_t FUTEX_WAKE_ALL           = 0xFFFFFFFFu;
 
+    /* Abnormal termination from any thread: ends the whole process (every
+       thread) with exit code TerminatedAborted (256+SIGABRT). SYS_EXIT from a
+       sibling thread ends only that thread, so abort() needs its own call. */
+    static constexpr uint64_t SYS_ABORT                = 198;  // () -> does not return
+
     /* Kernel-owned process capabilities. User identities may namespace
        per-user resources, but never participate in authorization decisions. */
     static constexpr uint64_t CAP_PROCESS_ADMIN = 1ULL << 0;

kernel/src/Common/TerminationCodes.hpp

@@ -0,0 +1,37 @@
+/*
+    * TerminationCodes.hpp
+    * MontaukOS process termination codes.
+    * Copyright (c) 2026 Daniel Hammer
+*/
+
+#pragma once
+
+#include <cstdint>
+
+// Exit code recorded when the kernel ends a process, as opposed to the
+// process calling SYS_EXIT (which is masked to 0..255). Encoded as
+// 256 + POSIX signal number so libc waitpid can report WTERMSIG.
+// Mirrored in userspace at programs/include/montauk/statuscodes.h.
+enum TerminationCodes {
+    TerminationBase = 256,
+    TerminatedIllegalInstruction = TerminationBase + 4,     // SIGILL
+    TerminatedBreakpoint = TerminationBase + 5,             // SIGTRAP
+    TerminatedAborted = TerminationBase + 6,                // SIGABRT
+    TerminatedArithmeticError = TerminationBase + 8,        // SIGFPE
+    TerminatedKilled = TerminationBase + 9,                 // SIGKILL
+    TerminatedAccessViolation = TerminationBase + 11        // SIGSEGV
+};
+
+// Termination code for a user-mode CPU exception. The exact vector is
+// kept in the crash report; this is only the category.
+inline TerminationCodes TerminationFromVector(uint8_t vector) {
+    switch (vector) {
+        case 0x06: return TerminatedIllegalInstruction;     // #UD
+        case 0x01:                                          // #DB
+        case 0x03: return TerminatedBreakpoint;             // #BP
+        case 0x00:                                          // #DE
+        case 0x10:                                          // #MF
+        case 0x13: return TerminatedArithmeticError;        // #XM
+        default:   return TerminatedAccessViolation;        // #PF, #GP, #SS, #NP, #AC, #OF, #BR, #CP, ...
+    }
+}

kernel/src/Hal/IDT.cpp

@@ -8,6 +8,7 @@
 
 #include <Memory/Heap.hpp>
 #include <Common/Panic.hpp>
+#include <Common/TerminationCodes.hpp>
 #include <Platform/Registers.hpp>
 #include <CppLib/Stream.hpp>
 #include <Memory/PageFrameAllocator.hpp>
@@ -170,23 +171,20 @@ namespace Hal {
             CrashReport::AddReport(rep);
             Sched::SpawnCrashPad(proc->pid);
 
-            // Record a killed-by-signal exit code (256+sig) so a parent
+            // Record a termination code (256+sig) so a parent blocked in
-            // blocked in SYS_WAITPID can tell a crash from a clean exit.
+            // SYS_WAITPID can tell a crash from a clean exit.
             {
-                int sig = 11;                       /* SIGSEGV */
+                int code = TerminationFromVector(i);
-                if (i == 0x00) sig = 8;             /* #DE -> SIGFPE */
-                else if (i == 0x06) sig = 4;        /* #UD -> SIGILL */
-                else if (i == 0x10 || i == 0x13) sig = 8;  /* x87/SIMD FP */
 
                 // ExitProcess from a sibling thread ends only that thread,
                 // which would leave the process running with the crash
                 // swallowed. Flag the whole process (main thread and every
                 // sibling) first, carrying the crash code rather than
-                // KillProcess's default SIGKILL, so waiters see the fault.
+                // KillProcess's default TerminatedKilled, so waiters see the fault.
                 if (Sched::GetCurrentThreadPtr() != proc) {
-                    Sched::KillProcess(proc->pid, 256 + sig);
+                    Sched::KillProcess(proc->pid, code);
                 } else {
-                    Sched::SetProcessExitCode(proc->pid, 256 + sig);
+                    Sched::SetProcessExitCode(proc->pid, code);
                 }
             }
 

kernel/src/Sched/Scheduler.cpp

@@ -1885,7 +1885,7 @@ namespace Sched {
                 continue;
             }
 
-            primary.exitCode = 256 + 9; /* killed (SIGKILL) */
+            primary.exitCode = TerminatedKilled;
             primary.killPending = true;
             if (primary.state == ProcessState::Blocked) {
                 primary.state = ProcessState::Ready;

kernel/src/Sched/Scheduler.hpp

@@ -6,6 +6,7 @@
 
 #pragma once
 #include <cstdint>
+#include <Common/TerminationCodes.hpp>
 #include <atomic>
 #include <Api/Syscall.hpp>
 
@@ -303,9 +304,9 @@ namespace Sched {
 
     // Kill a process by PID. If the process is running on another CPU,
     // sets a kill-pending flag checked on the next timer tick. exitCode is
-    // what a waiter sees (256+sig; SIGKILL by default).
+    // what a waiter sees (a TerminationCodes value).
     // Returns 0 on success, -1 on failure.
-    int KillProcess(int pid, int exitCode = 256 + 9);
+    int KillProcess(int pid, int exitCode = TerminatedKilled);
 
     // Start a new process session for the caller, or terminate every process
     // belonging to a session. KillSession returns the number of live members

programs/include/Api/Syscall.hpp

@@ -288,6 +288,11 @@ namespace montauk::abi {
     static constexpr uint64_t FUTEX_WAIT_FOREVER       = ~0ULL;
     static constexpr uint32_t FUTEX_WAKE_ALL           = 0xFFFFFFFFu;
 
+    /* Abnormal termination from any thread: ends the whole process (every
+       thread) with exit code TerminatedAborted (256+SIGABRT). SYS_EXIT from a
+       sibling thread ends only that thread, so abort() needs its own call. */
+    static constexpr uint64_t SYS_ABORT                = 198;  // () -> does not return
+
     /* Kernel-owned process capabilities. User identities may namespace
        per-user resources, but never participate in authorization decisions. */
     static constexpr uint64_t CAP_PROCESS_ADMIN = 1ULL << 0;

programs/include/libc/montauk.h

@@ -221,6 +221,7 @@ extern "C" {
 #define MTK_SYS_CHILDIO_WRITEKEY_EX 195
 #define MTK_SYS_FUTEX_WAIT          196
 #define MTK_SYS_FUTEX_WAKE          197
+#define MTK_SYS_ABORT               198
 /* @SYSCALLS-END */
 
 /* Syscall status codes (montauk/statuscodes.h for C++). */

programs/include/montauk/statuscodes.h

@@ -101,6 +101,33 @@ inline const char* GetStatusExplanationText(StatusCode statusCode) {
     return GetStatusText(statusCode);
 }
 
+// Process termination codes: what waitpid returns when the kernel ended the
+// process (crash, kill, abort) instead of it calling exit. 256 + POSIX
+// signal number, so normal exit codes (0..255) can never collide.
+// Analogous to kernel/src/Common/TerminationCodes.hpp; same values.
+typedef enum {
+    TerminationBase = 256,
+    TerminatedIllegalInstruction = TerminationBase + 4,     // SIGILL
+    TerminatedBreakpoint = TerminationBase + 5,             // SIGTRAP
+    TerminatedAborted = TerminationBase + 6,                // SIGABRT
+    TerminatedArithmeticError = TerminationBase + 8,        // SIGFPE
+    TerminatedKilled = TerminationBase + 9,                 // SIGKILL
+    TerminatedAccessViolation = TerminationBase + 11        // SIGSEGV
+} TerminationCode;
+
+// Shared with C (libc.c), so no nullptr. Returns 0 for an unknown code.
+inline const char* GetTerminationText(int exitCode) {
+    switch (exitCode) {
+        case TerminatedIllegalInstruction: return "Illegal instruction";
+        case TerminatedBreakpoint:         return "Breakpoint";
+        case TerminatedAborted:            return "Aborted";
+        case TerminatedArithmeticError:    return "Arithmetic error";
+        case TerminatedKilled:             return "Killed";
+        case TerminatedAccessViolation:    return "Access violation";
+        default:                           return 0;
+    }
+}
+
 #ifdef __cplusplus
 }
 #endif

programs/include/montauk/syscall.h

@@ -527,6 +527,11 @@ namespace montauk {
     inline int kill(int pid) {
         return (int)syscall1(montauk::abi::SYS_KILL, (uint64_t)pid);
     }
+    // End the whole process from any thread (exit code TerminatedAborted).
+    [[noreturn]] inline void abort() {
+        syscall0(montauk::abi::SYS_ABORT);
+        __builtin_unreachable();
+    }
     inline int setsession() {
         return (int)syscall0(montauk::abi::SYS_SETSESSION);
     }

programs/lib/libc/libc.c

@@ -130,6 +130,7 @@ static inline long _mtk_syscall4(long nr, long a1, long a2, long a3, long a4) {
 #define SYS_GETENVIRON 171
 #define SYS_SETENVIRON 172
 #define SYS_SPAWN_ENV 173
+#define SYS_ABORT     198
 
 /* ========================================================================
    errno
@@ -1243,9 +1244,9 @@ void exit(int status) {
     __builtin_unreachable();
 }
 
+/* Ends the whole process from any thread; waitpid sees WTERMSIG == SIGABRT. */
 void abort(void) {
-    _mtk_syscall1(SYS_PRINT, (long)"abort() called\n");
+    _mtk_syscall0(SYS_ABORT);
-    _mtk_syscall1(SYS_EXIT, 1);
     __builtin_unreachable();
 }
 
@@ -4055,8 +4056,8 @@ pid_t waitpid(pid_t pid, int *status, int options) {
     }
     long code = _mtk_syscall1(SYS_WAITPID, (long)pid);
     if (status != NULL) {
-        if (code >= 256) {
+        if (code >= TerminationBase) {
-            *status = (int)((code - 256) & 0x7F);   /* signaled */
+            *status = (int)((code - TerminationBase) & 0x7F);   /* signaled */
         } else {
             *status = (int)((code & 0xFF) << 8);    /* exited */
         }

programs/rust/montauk-rt/src/process.rs

@@ -18,16 +18,12 @@ pub fn id() -> u32 {
     unsafe { sys::syscall0(sys::SYS_GETPID) as u32 }
 }
 
-/// Terminate the whole process from any thread.
+/// Terminate the whole process from any thread. Waiters see exit code
+/// TerminatedAborted (256 + SIGABRT).
 pub fn abort() -> ! {
     unsafe {
-        if crate::thread::current_id() == id() {
+        sys::syscall0(sys::SYS_ABORT);
-            sys::syscall1(sys::SYS_EXIT, 134);
+        // Not reached. No panic here: the panic handler calls abort().
-        } else {
-            // Sibling: SYS_EXIT would end only this thread. Self-kill flags
-            // every thread; park here until the kernel reaps us.
-            sys::syscall1(sys::SYS_KILL, id() as u64);
-        }
         loop {
             sys::syscall0(sys::SYS_YIELD);
         }

programs/src/shell/exec.cpp

@@ -23,9 +23,9 @@ static void print_exit_code(const int exitCode) {
     if (code == 0) return;
     char buf[16];
     int n = 0;
-    if (code >= 256) {
+    if (code >= montauk::TerminationBase) {
         montauk::print("[terminated by signal ");
-        code -= 256;
+        code -= montauk::TerminationBase;
     } else {
         montauk::print("[exit code ");
     }
@@ -39,13 +39,16 @@ static void print_exit_code(const int exitCode) {
         montauk::print(c);
     }
     
-    if (exitCode > 0 && exitCode <= montauk::MaxStatusCode) {
+    const char* statusText = nullptr;
-        const char* statusText = montauk::GetStatusText((montauk::StatusCode)exitCode);
+    if (exitCode >= montauk::TerminationBase) {
+        statusText = montauk::GetTerminationText(exitCode);
+    } else if (exitCode > 0 && exitCode <= montauk::MaxStatusCode) {
+        statusText = montauk::GetStatusText((montauk::StatusCode)exitCode);
+    }
 
-        if (statusText != nullptr) {
+    if (statusText != nullptr) {
-            montauk::print(" - ");
+        montauk::print(" - ");
-            montauk::print(statusText);
+        montauk::print(statusText);
-        }
     }
 
     montauk::print("]\n");