x86_64: allocate signal trampoline in thread user space

src/platform/x86_64/ipc/signal.c

@@ -0,0 +1,30 @@
+/*
+ * lux - a lightweight unix-like operating system
+ * Omar Elghoul, 2024
+ * 
+ * Platform-Specific Code for x86_64
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <platform/platform.h>
+#include <platform/context.h>
+#include <kernel/signal.h>
+#include <kernel/sched.h>
+
+extern size_t sigstubSize;
+extern uint8_t sigstub[];
+
+/* platformSignalSetup(): sets up the signal trampoline code in a user process
+ * params: t - thread structure
+ * returns: zero on success
+ */
+
+int platformSignalSetup(Thread *t) {
+    void *trampoline = uxmalloc(sigstubSize);
+    if(!trampoline) return -1;
+
+    memcpy(trampoline, sigstub, sigstubSize);
+    t->signalTrampoline = (uintptr_t) trampoline;
+    return 0;
+}