Use callee-saved registers to pass args through fork_trampoline().

2 files changed, 9 insertions, 17 deletions

diff --git a/sys/riscv/riscv/swtch.S b/sys/riscv/riscv/swtch.S
index c6336a9..413e666 100644
--- a/sys/riscv/riscv/swtch.S
+++ b/sys/riscv/riscv/swtch.S
@@ -109,14 +109,10 @@ ENTRY(cpu_switch)
 	/* Save the old context. */
 	ld	x13, TD_PCB(a0)
 
-	/* Store the callee-saved registers */
+	/* Store ra, sp and the callee-saved registers */
 	sd	ra, (PCB_RA)(x13)
 	sd	sp, (PCB_SP)(x13)
 
-	/* We use these in fork_trampoline */
-	sd	t0, (PCB_T + 0 * 8)(x13)
-	sd	t1, (PCB_T + 1 * 8)(x13)
-
 	/* s[0-11] */
 	sd	s0, (PCB_S + 0 * 8)(x13)
 	sd	s1, (PCB_S + 1 * 8)(x13)
@@ -167,10 +163,6 @@ ENTRY(cpu_switch)
 	ld	ra, (PCB_RA)(x13)
 	ld	sp, (PCB_SP)(x13)
 
-	/* We use these in fork_trampoline */
-	ld	t0, (PCB_T + 0 * 8)(x13)
-	ld	t1, (PCB_T + 1 * 8)(x13)
-
 	/* s[0-11] */
 	ld	s0, (PCB_S + 0 * 8)(x13)
 	ld	s1, (PCB_S + 1 * 8)(x13)
@@ -195,8 +187,8 @@ END(cpu_switch)
  */
 
 ENTRY(fork_trampoline)
-	mv	a0, x5
-	mv	a1, x6
+	mv	a0, s0
+	mv	a1, s1
 	mv	a2, sp
 	call	_C_LABEL(fork_exit)
 
diff --git a/sys/riscv/riscv/vm_machdep.c b/sys/riscv/riscv/vm_machdep.c
index 5ea352b..49d31ba 100644
--- a/sys/riscv/riscv/vm_machdep.c
+++ b/sys/riscv/riscv/vm_machdep.c
@@ -97,8 +97,8 @@ cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
 	td2->td_frame = tf;
 
 	/* Set the return value registers for fork() */
-	td2->td_pcb->pcb_t[0] = (uintptr_t)fork_return;
-	td2->td_pcb->pcb_t[1] = (uintptr_t)td2;
+	td2->td_pcb->pcb_s[0] = (uintptr_t)fork_return;
+	td2->td_pcb->pcb_s[1] = (uintptr_t)td2;
 	td2->td_pcb->pcb_ra = (uintptr_t)fork_trampoline;
 	td2->td_pcb->pcb_sp = (uintptr_t)td2->td_frame;
 
@@ -165,8 +165,8 @@ cpu_set_upcall(struct thread *td, struct thread *td0)
 	bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
 	bcopy(td0->td_pcb, td->td_pcb, sizeof(struct pcb));
 
-	td->td_pcb->pcb_t[0] = (uintptr_t)fork_return;
-	td->td_pcb->pcb_t[1] = (uintptr_t)td;
+	td->td_pcb->pcb_s[0] = (uintptr_t)fork_return;
+	td->td_pcb->pcb_s[1] = (uintptr_t)td;
 	td->td_pcb->pcb_ra = (uintptr_t)fork_trampoline;
 	td->td_pcb->pcb_sp = (uintptr_t)td->td_frame;
 
@@ -240,8 +240,8 @@ void
 cpu_set_fork_handler(struct thread *td, void (*func)(void *), void *arg)
 {
 
-	td->td_pcb->pcb_t[0] = (uintptr_t)func;
-	td->td_pcb->pcb_t[1] = (uintptr_t)arg;
+	td->td_pcb->pcb_s[0] = (uintptr_t)func;
+	td->td_pcb->pcb_s[1] = (uintptr_t)arg;
 	td->td_pcb->pcb_ra = (uintptr_t)fork_trampoline;
 	td->td_pcb->pcb_sp = (uintptr_t)td->td_frame;
 }