initial spawn implementation

7 files changed, 28 insertions, 17 deletions

diff --git a/arch/riscv64/kernel/entry.S b/arch/riscv64/kernel/entry.S
index 8ff642a..db662bb 100644
--- a/arch/riscv64/kernel/entry.S
+++ b/arch/riscv64/kernel/entry.S
@@ -87,7 +87,8 @@ handle_syscall:
 	 * twice */
 	csrr    s0, CSR_SEPC
 	addi	s0, s0, 4
-	csrw	CSR_SEPC, s0
+	/* store execution continuation point */
+	sr	s0, 0(tp)
 	/* allocate space for sys_ret structure on stack and shift argument
 	 * registers down one to make room for the pointer to this structure */
 	addi	sp, sp, -sizeof_sys_ret
@@ -112,6 +113,9 @@ handle_syscall:
 	/* get associated kernel stack */
 	mv	sp, tp
 	addi	sp, sp, -sizeof_registers
+	/* set execution continuation */
+	lr	s0, 0(tp)
+	csrw	CSR_SEPC, s0
 	/* restore system call result */
 	j	restore_noreturn
 
diff --git a/arch/riscv64/kernel/proc.c b/arch/riscv64/kernel/proc.c
index ab833b2..f85f597 100644
--- a/arch/riscv64/kernel/proc.c
+++ b/arch/riscv64/kernel/proc.c
@@ -15,6 +15,7 @@ stat_t run_init(struct tcb *t, void *fdt)
 {
 	/** \todo actually map fdt into the target address space */
 	csr_write(CSR_SSCRATCH, t);
+	csr_write(CSR_SEPC, t->exec);
 	__asm__ volatile ("mv sp, %0\n" : : "r" (t->thread_stack_top) : "memory");
 	__asm__ volatile ("mv a0, %0\n" : : "r" (fdt) : );
 	__asm__ volatile ("sret\n" ::: "memory");
@@ -22,12 +23,6 @@ stat_t run_init(struct tcb *t, void *fdt)
 	return ERR_ADDR;
 }
 
-stat_t set_return(vm_t v)
-{
-	csr_write(CSR_SEPC, v);
-	return OK;
-}
-
 stat_t set_ipc(struct tcb *t, id_t pid, id_t tid)
 {
 	struct riscv_regs *r = (struct riscv_regs *)(--t);
diff --git a/common/proc.c b/common/proc.c
index b2caa54..6a3bedf 100644
--- a/common/proc.c
+++ b/common/proc.c
@@ -23,7 +23,7 @@ stat_t prepare_proc(struct tcb *t, vm_t bin, vm_t interp)
 
 	alloc_stacks(t);
 	set_thread(t);
-	set_return(entry);
+	set_return(t, entry);
 	return OK;
 }
 
diff --git a/common/tcb.c b/common/tcb.c
index 8ff86ab..f618cd6 100644
--- a/common/tcb.c
+++ b/common/tcb.c
@@ -342,3 +342,8 @@ stat_t clone_proc_maps(struct tcb *r)
 
 	return OK;
 }
+
+void set_return(struct tcb *t, vm_t v)
+{
+	t->exec = v;
+}
diff --git a/common/uapi/proc.c b/common/uapi/proc.c
index d1d2bd7..a668246 100644
--- a/common/uapi/proc.c
+++ b/common/uapi/proc.c
@@ -91,7 +91,11 @@ SYSCALL_DEFINE2(exec)(sys_arg_t bin, sys_arg_t interp){
  */
 SYSCALL_DEFINE2(spawn)(sys_arg_t bin, sys_arg_t interp)
 {
-	/* @todo implement */
+	struct tcb *t = create_proc(NULL);
+	if (!t)
+		return (struct sys_ret){ERR_OOMEM, 0, 0, 0, 0, 0};
+
+	return (struct sys_ret){prepare_proc(t, bin, interp), t->pid, 0, 0, 0, 0};
 }
 
 /**
diff --git a/include/apos/tcb.h b/include/apos/tcb.h
index 63bf037..a31e308 100644
--- a/include/apos/tcb.h
+++ b/include/apos/tcb.h
@@ -75,6 +75,9 @@ enum tcb_notify {
 
 /** Thread control block. Main way to handle threads. */
 struct tcb {
+	/** Execution continuation point. Important that it is first. */
+	vm_t exec;
+
 	/** Arch-specific data. */
 	struct arch_tcbd tcbd;
 
@@ -319,4 +322,12 @@ stat_t clone_rpc_maps(struct tcb *r);
  */
 stat_t alloc_stacks(struct tcb *t);
 
+/**
+ * Set address to jump to when returning to userspace.
+ *
+ * @param t Thread return address to set.
+ * @param r Address to jump to.
+ */
+void set_return(struct tcb *t, vm_t r);
+
 #endif /* APOS_TCB_H */
diff --git a/include/arch/proc.h b/include/arch/proc.h
index dd739bf..d5367f6 100644
--- a/include/arch/proc.h
+++ b/include/arch/proc.h
@@ -16,14 +16,6 @@
 #endif
 
 /**
- * Set address to jump to when returning to userspace.
- *
- * @param r Address to jump to.
- * @return \ref OK.
- */
-stat_t set_return(vm_t r);
-
-/**
  * Attach IPC data to load into argument registers when returning to userspace.
  *
  * @param t Thread that will run after return.