ptos/amd64+ke: Add system call groundwork + exit syscall

Signed-off-by: Chloe M. <chloe@mensia.org>

sdk/head/ptapi/syscall.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: System calls
+ * Author:      Chloe M.
+ */
+
+#ifndef _PTAPI_SYSCALL_H_
+#define _PTAPI_SYSCALL_H_ 1
+
+#define SYS_NOP  0x00       /* Does nothing / reserved */
+#define SYS_EXIT 0x01       /* Exit the current thread */
+#define _SYSCALL_MAX 0x02   /* Always bump when adding new system call */
+
+#endif  /* !_PTAPI_SYSCALL_H_ */

service/ptos/arch/amd64/cpu/init.c

@@ -38,6 +38,7 @@ InitInterrupts(VOID)
     MdIdtSetGate(0x0C, (UPTR)TrapStackSegmentFault, IDT_TRAP_GATE, 0);
     MdIdtSetGate(0x0D, (UPTR)TrapGeneralProtection, IDT_TRAP_GATE, 0);
     MdIdtSetGate(0x0E, (UPTR)TrapPageFault, IDT_TRAP_GATE, 0);
+    MdIdtSetGate(0x2E, (UPTR)TrapLegacySyscall, IDT_USER_GATE, 0);
     MdIdtLoad();
 }
 

service/ptos/arch/amd64/cpu/vector.S

@@ -151,3 +151,10 @@ LapicTmrIsr:
     call HalContextSwitch
     call MdLapicSendEoi
     INTR_EXIT()
+
+    .globl TrapLegacySyscall
+TrapLegacySyscall:
+    INTR_ENTRY($0x2C)
+    mov %rsp, %rdi
+    call MdSyscallDispatch
+    INTR_EXIT()

service/ptos/arch/amd64/ke/syscall.c

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: System call dispatch
+ * Author:      Chloe M.
+ */
+
+#include <ke/syscall.h>
+#include <machine/frame.h>
+
+/*
+ * Dispatch incoming system calls
+ *
+ * @Frame:  Trapframe snapshot
+ */
+VOID
+MdSyscallDispatch(TRAP_FRAME *Frame)
+{
+    SYSCALL_ARGS ScArgs;
+
+    if (Frame == NULL) {
+        return;
+    }
+
+    /* Is this system call number valid? */
+    if (Frame->Rax == 0 || Frame->Rax >= _SYSCALL_MAX) {
+        Frame->Rax = STATUS_INVALID_PARAM;
+        return;
+    }
+
+    ScArgs.Arg[0] = Frame->Rdi;
+    ScArgs.Arg[1] = Frame->Rsi;
+    ScArgs.Arg[2] = Frame->Rdx;
+    ScArgs.Arg[3] = Frame->Rcx;
+    ScArgs.Arg[4] = Frame->R8;
+    ScArgs.Arg[5] = Frame->R9;
+    SystemCallTable[Frame->Rax](&ScArgs);
+}

service/ptos/head/arch/amd64/trap.h

@@ -28,6 +28,7 @@
 #define TRAP_STACK_SEG_FAULT    0x0C
 #define TRAP_GENERAL_PROTECTION 0x0D
 #define TRAP_PAGE_FAULT         0x0E
+#define TRAP_SYSCALL            0x2E
 
 /* Prototypes of trap functions */
 VOID TrapDivError(VOID);

service/ptos/head/ke/syscall.h

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: System calls
+ * Author:      Chloe M.
+ */
+
+#ifndef _KE_SYSCALL_H_
+#define _KE_SYSCALL_H_ 1
+
+#include <ptapi/status.h>
+#include <ptapi/syscall.h>
+#include <ptdef.h>
+
+/*
+ * System call arguments passed to system call handlers
+ */
+typedef struct {
+    UQUAD Arg[6];
+} SYSCALL_ARGS;
+
+extern PT_STATUS(*SystemCallTable[_SYSCALL_MAX])(SYSCALL_ARGS *Args);
+
+#endif  /* !_KE_SYSCALL_H_ */

service/ptos/head/ps/uapi.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Process related user-API
+ * Author:      Chloe M.
+ */
+
+#ifndef _PS_UAPI_H_
+#define _PS_UAPI_H_ 1
+
+#include <ps/thread.h>
+#include <ke/syscall.h>
+
+/*
+ * Exit the current thread:
+ *
+ * @ARG[0]:  Exit status code
+ */
+PT_STATUS PsSysThreadExit(SYSCALL_ARGS *Args);
+
+#endif  /* !_PS_UAPI_H_ */

service/ptos/ke/syscall.c

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: System calls
+ * Author:      Chloe M.
+ */
+
+#include <ptdef.h>
+#include <ke/syscall.h>
+#include <ps/uapi.h>
+
+/* System call table */
+PT_STATUS(*SystemCallTable[_SYSCALL_MAX])(SYSCALL_ARGS *Args) = {
+    [SYS_EXIT] = PsSysThreadExit
+};

service/ptos/ps/thread_uapi.c

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Thread related user-API
+ * Author:      Chloe M.
+ */
+
+#include <ps/uapi.h>
+#include <ps/thread.h>
+
+#include <ex/trace.h>
+
+PT_STATUS
+PsSysThreadExit(SYSCALL_ARGS *Args)
+{
+    PsExitThread(Args->Arg[0]);
+    UNREACHABLE();
+}