Unverified Commit ab9164da authored by Jisheng Zhang's avatar Jisheng Zhang Committed by Palmer Dabbelt
Browse files

riscv: entry: Consolidate ret_from_kernel_thread into ret_from_fork 



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: default avatarJisheng Zhang <jszhang@kernel.org>
Reviewed-by: default avatarBjörn Töpel <bjorn@rivosinc.com>
Reviewed-by: default avatarGuo Ren <guoren@kernel.org>
Tested-by: default avatarGuo Ren <guoren@kernel.org>
Signed-off-by: default avatarGuo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20230222033021.983168-7-guoren@kernel.org


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 0bf298ad

arch/riscv/kernel/entry.S

+3 −9
Original line number Diff line number Diff line
@@ -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)
@@ -334,20 +333,15 @@ 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

arch/riscv/kernel/process.c

+2 −3
Original line number Diff line number Diff line
@@ -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)

{
@@ -173,7 +172,6 @@ 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 {
@@ -183,8 +181,9 @@ 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;

}