kern: Add syscall entry and SYS_exit syscall

Signed-off-by: Ian Moffett <ian@osmora.org>

8 files changed, 187 insertions, 0 deletions

diff --git a/src/sys/arch/amd64/cpu/cpu_conf.c b/src/sys/arch/amd64/cpu/cpu_conf.c
index e462ef3..531f53b 100644
--- a/src/sys/arch/amd64/cpu/cpu_conf.c
+++ b/src/sys/arch/amd64/cpu/cpu_conf.c
@@ -36,6 +36,8 @@
 #include <machine/gdt.h>
 #include <string.h>
 
+extern void syscall_isr(void);
+
 /*
  * Initialize interrupt vectors
  */
@@ -54,6 +56,7 @@ init_vectors(void)
     idt_set_desc(0xC, IDT_TRAP_GATE, ISR(ss_fault), 0);
     idt_set_desc(0xD, IDT_TRAP_GATE, ISR(general_prot), 0);
     idt_set_desc(0xE, IDT_TRAP_GATE, ISR(page_fault), 0);
+    idt_set_desc(0x80, IDT_USER_GATE, ISR(syscall_isr), 0);
 }
 
 void
diff --git a/src/sys/arch/amd64/cpu/trap.S b/src/sys/arch/amd64/cpu/trap.S
index ef5c14f..6e4d58c 100644
--- a/src/sys/arch/amd64/cpu/trap.S
+++ b/src/sys/arch/amd64/cpu/trap.S
@@ -107,3 +107,9 @@ INTR_ENTRY(lapic_tmr_isr)
     mov %rsp, %rdi
     call md_sched_switch
 INTR_EXIT(lapic_tmr_isr)
+
+    .global syscall_isr
+INTR_ENTRY(syscall_isr)
+    mov %rsp, %rdi
+    call trap_syscall
+INTR_EXIT(syscall_isr)
diff --git a/src/sys/arch/amd64/cpu/trap.c b/src/sys/arch/amd64/cpu/trap.c
index 046263b..6ddc079 100644
--- a/src/sys/arch/amd64/cpu/trap.c
+++ b/src/sys/arch/amd64/cpu/trap.c
@@ -36,6 +36,7 @@
 #include <sys/cdefs.h>
 #include <sys/panic.h>
 #include <sys/syslog.h>
+#include <sys/syscall.h>
 #include <machine/trap.h>
 
 /*
@@ -146,6 +147,24 @@ trapframe_dump(struct trapframe *tf)
 }
 
 void
+trap_syscall(struct trapframe *tf)
+{
+    struct syscall_args scargs = {
+        .arg[0] = tf->rdi,
+        .arg[1] = tf->rsi,
+        .arg[2] = tf->rdx,
+        .arg[3] = tf->r10,
+        .arg[4] = tf->r9,
+        .arg[5] = tf->r8,
+        .tf = tf
+    };
+
+    if (tf->rax < MAX_SYSCALLS && tf->rax > 0) {
+        tf->rax = g_sctab[tf->rax](&scargs);
+    }
+}
+
+void
 trap_handler(struct trapframe *tf)
 {
     trapframe_dump(tf);
diff --git a/src/sys/include/arch/amd64/trap.h b/src/sys/include/arch/amd64/trap.h
index 53f38e8..4b6e33a 100644
--- a/src/sys/include/arch/amd64/trap.h
+++ b/src/sys/include/arch/amd64/trap.h
@@ -62,6 +62,7 @@ void general_prot(void *sf);
 void page_fault(void *sf);
 void nmi(void *sf);
 void ss_fault(void *sf);
+void trap_syscall(struct trapframe *tf);
 void trap_handler(struct trapframe *tf);
 
 #endif  /* !__ASSEMBLER__ */
diff --git a/src/sys/include/sys/proc.h b/src/sys/include/sys/proc.h
index c7d3a39..1b1636c 100644
--- a/src/sys/include/sys/proc.h
+++ b/src/sys/include/sys/proc.h
@@ -31,6 +31,7 @@
 #define _SYS_PROC_H_
 
 #include <sys/types.h>
+#include <sys/syscall.h>
 #include <sys/cdefs.h>
 #include <sys/param.h>
 #include <sys/queue.h>
@@ -131,5 +132,11 @@ __dead void md_proc_yield(void);
  * @procp: Process pointer
  */
 __dead void md_proc_kick(struct proc *procp);
+
+/*
+ * Exit the current process - exit(2) syscall
+ */
+scret_t sys_exit(struct syscall_args *scargs);
+
 #endif  /* !_KERNEL */
 #endif  /* !_SYS_PROC_H_ */
diff --git a/src/sys/include/sys/syscall.h b/src/sys/include/sys/syscall.h
new file mode 100644
index 0000000..108f164
--- /dev/null
+++ b/src/sys/include/sys/syscall.h
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _SYS_SYSCALL_H_
+#define _SYS_SYSCALL_H_
+
+#include <sys/types.h>
+
+/*
+ * Syscall numbers
+ */
+#define SYS_none    0x00
+#define SYS_exit    0x01
+
+#if defined(_KERNEL)
+/*
+ * Acquire a specific syscall argument
+ */
+#define SCARG(SCARGS, TYPE, SYSNO) ((TYPE)(SCARGS)->arg[(SYSNO)])
+
+typedef ssize_t scret_t;
+typedef ssize_t scarg_t;
+
+struct syscall_args {
+    scarg_t arg[6];
+    struct trapframe *tf;
+};
+
+extern scret_t(*g_sctab[])(struct syscall_args *);
+extern const size_t MAX_SYSCALLS;
+
+#endif  /* _KERNEL */
+
+#endif  /* !_SYS_SYSCALL_H_ */
diff --git a/src/sys/os/os_syscall.c b/src/sys/os/os_syscall.c
new file mode 100644
index 0000000..060f774
--- /dev/null
+++ b/src/sys/os/os_syscall.c
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/proc.h>
+
+scret_t(*g_sctab[])(struct syscall_args *) = {
+    [SYS_none]   = NULL,
+    [SYS_exit]   = sys_exit
+};
+
+const size_t MAX_SYSCALLS = NELEM(g_sctab);
diff --git a/src/sys/os/proc_syscall.c b/src/sys/os/proc_syscall.c
new file mode 100644
index 0000000..e71d546
--- /dev/null
+++ b/src/sys/os/proc_syscall.c
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/syscall.h>
+#include <sys/cpuvar.h>
+#include <sys/types.h>
+#include <sys/proc.h>
+#include <sys/cdefs.h>
+#include <sys/param.h>
+
+#include <sys/syslog.h>
+
+/*
+ * ARG 0: Status
+ */
+__dead scret_t
+sys_exit(struct syscall_args *scargs)
+{
+    struct pcore *core = this_core();
+    int status;
+
+    status = SCARG(scargs, int, 0);
+    proc_kill(core->curproc, status);
+    md_proc_yield();    /* unreachable */
+}