[PATCH -next V12 6/7] riscv: entry: Consolidate ret_from_kernel_thread into ret_from_fork

guoren
2023-01-03T03:37:19Z

From: Jisheng Zhang <jszhang@kernel.org>

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
achieved by testing fn is NULL or not, I.E s0 is 0 or not. Many
architectures have done the same thing, it makes entry.S more clean.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Tested-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Guo Ren <guoren@kernel.org>
---
arch/riscv/kernel/entry.S | 12 +++---------
arch/riscv/kernel/process.c | 5 ++---
2 files changed, 5 insertions(+), 12 deletions(-)

diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 997886fb37a2..1a36e313adc4 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -132,7 +132,6 @@ SYM_CODE_END(handle_exception)
* caller list:
* - handle_exception
* - ret_from_fork
- * - ret_from_kernel_thread
*/
SYM_CODE_START_NOALIGN(ret_from_exception)
REG_L s0, PT_STATUS(sp)
@@ -336,20 +335,15 @@ SYM_CODE_END(handle_kernel_stack_overflow)

SYM_CODE_START(ret_from_fork)
call schedule_tail
- move a0, sp /* pt_regs */
- la ra, ret_from_exception
- tail syscall_exit_to_user_mode
-SYM_CODE_END(ret_from_fork)
-
-SYM_CODE_START(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
-SYM_CODE_END(ret_from_kernel_thread)
+SYM_CODE_END(ret_from_fork)

/*
* Integer register context switch
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 8955f2432c2d..46806d5d10fa 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;
}
--
2.36.1