feat: add SYS_FUTEX_WAIT and SYS_FUTEX_WAKE syscalls; revamp desktop application categories

kernel/src/Api/BuildNo.hpp

@@ -12,4 +12,4 @@
 
 #pragma once
 
-#define MONTAUK_BUILD_NUMBER 296
+#define MONTAUK_BUILD_NUMBER 302

kernel/src/Api/Process.hpp

@@ -302,6 +302,14 @@ namespace montauk::abi {
         return Sched::GetCurrentTid();
     }
 
+    static int Sys_FutexWait(uint64_t addr, uint32_t expected, uint64_t timeoutNs) {
+        return Sched::FutexWait(addr, expected, timeoutNs);
+    }
+
+    static int Sys_FutexWake(uint64_t addr, uint32_t count) {
+        return Sched::FutexWake(addr, count);
+    }
+
     static int Sys_Chdir(const char* path) {
         auto* proc = Sched::GetCurrentProcessPtr();
         if (proc == nullptr || path == nullptr) return InvalidArgument;

kernel/src/Api/Syscall.cpp

@@ -545,6 +545,13 @@ namespace montauk::abi {
                 return Sys_ThreadJoin((int)frame->arg1, (int*)frame->arg2);
             case SYS_THREAD_SELF:
                 return Sys_ThreadSelf();
+            case SYS_FUTEX_WAIT:
+                // Validation demand-commits the page so the scheduler can
+                // read the word with its lock held without faulting.
+                if (!UserMemory::Readable<uint32_t>(frame->arg1)) return BadPointer;
+                return Sys_FutexWait(frame->arg1, (uint32_t)frame->arg2, frame->arg3);
+            case SYS_FUTEX_WAKE:
+                return Sys_FutexWake(frame->arg1, (uint32_t)frame->arg2);
             case SYS_BTSCAN:
                 if (!Sched::HasCapability(CAP_DEVICE_ADMIN)) return CapabilityDenied;
                 if ((int64_t)frame->arg2 < 0) return InvalidArgument;

kernel/src/Api/Syscall.hpp

@@ -364,6 +364,17 @@ namespace montauk::abi {
     static constexpr uint64_t SYS_GETKEY_EX            = 194;  // (KeyEvent*, size) -> 0; blocks like SYS_GETKEY
     static constexpr uint64_t SYS_CHILDIO_WRITEKEY_EX  = 195;  // (childPid, const KeyEvent*, size) -> status
 
+    /* Futexes: process-private wait queues keyed by a user address. WAIT
+       blocks only if *addr still equals `expected` (checked atomically with
+       enrollment). timeoutNs: FUTEX_WAIT_FOREVER = no deadline, 0 = check
+       only; rounded up to the 1 ms scheduler tick. WAIT returns 0 when woken,
+       WouldBlock on value mismatch, TimedOut on deadline. WAKE returns the
+       number of threads woken (count = FUTEX_WAKE_ALL wakes every waiter). */
+    static constexpr uint64_t SYS_FUTEX_WAIT           = 196;  // (uint32_t* addr, expected, timeoutNs) -> status
+    static constexpr uint64_t SYS_FUTEX_WAKE           = 197;  // (uint32_t* addr, count) -> woken, or status
+    static constexpr uint64_t FUTEX_WAIT_FOREVER       = ~0ULL;
+    static constexpr uint32_t FUTEX_WAKE_ALL           = 0xFFFFFFFFu;
+
     /* 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;