[PATCH v3 2/4] riscv: consolidate ret_from_kernel_thread into ret_from_fork

Jisheng Zhang
2022-10-03T10:39:10Z

The ret_from_kernel_thread() behaves similarly with ret_from_fork(),
the only difference is whether call the fn(arg) or not, this can be
acchieved by testing fn is NULL or not, I.E s0 is 0 or not.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Acked-by: Guo Ren <guoren@kernel.org>
---
arch/riscv/kernel/entry.S | 11 +++--------
arch/riscv/kernel/process.c | 5 ++---
2 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 39097c1474a0..d227aca7f9d4 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -323,20 +323,15 @@ END(handle_kernel_stack_overflow)

ENTRY(ret_from_fork)
call schedule_tail
- move a0, sp /* pt_regs */
- la ra, ret_from_exception
- tail syscall_exit_to_user_mode
-ENDPROC(ret_from_fork)
-
-ENTRY(ret_from_kernel_thread)
- call schedule_tail
+ beqz s0, 1f /* not from kernel thread */
/* Call fn(arg) */
move a0, s1
jalr s0
+1:
move a0, sp /* pt_regs */
la ra, ret_from_exception
tail syscall_exit_to_user_mode
-ENDPROC(ret_from_kernel_thread)
+ENDPROC(ret_from_fork)

/*
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 52002d54b163..fdafed185e21 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -34,7 +34,6 @@ EXPORT_SYMBOL(__stack_chk_guard);
#endif

extern asmlinkage void ret_from_fork(void);
-extern asmlinkage void ret_from_kernel_thread(void);

void arch_cpu_idle(void)
{
@@ -174,7 +173,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
/* Supervisor/Machine, irqs on: */
childregs->status = SR_PP | SR_PIE;

- p->thread.ra = (unsigned long)ret_from_kernel_thread;
p->thread.s[0] = (unsigned long)args->fn;
p->thread.s[1] = (unsigned long)args->fn_arg;
} else {
@@ -184,8 +182,9 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
if (clone_flags & CLONE_SETTLS)
childregs->tp = tls;
childregs->a0 = 0; /* Return value of fork() */
- p->thread.ra = (unsigned long)ret_from_fork;
+ p->thread.s[0] = 0;
}
+ p->thread.ra = (unsigned long)ret_from_fork;
p->thread.sp = (unsigned long)childregs; /* kernel sp */
return 0;
}
--
2.37.2