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riscv: entry: Consolidate ret_from_kernel_thread into ret_from_fork

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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>
Link: https://lore.kernel.org/r/20230222033021.983168-7-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Jisheng Zhang 2023-02-21 22:30:20 -05:00 • committed by Palmer Dabbelt
parent 0bf298ad2b
commit ab9164dae2
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GPG key ID: 2E1319F35FBB1889
2 changed files with 7 additions and 14 deletions
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16
arch/riscv/kernel/entry.S
View file

@ -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)
@ -334,21 +333,16 @@ SYM_CODE_END(handle_kernel_stack_overflow)
SYM_CODE_START(ret_from_fork)
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_fork)
SYM_CODE_START(ret_from_kernel_thread)
call schedule_tail
/* Call fn(arg) */
move a0, s1
jalr s0
move a0, sp /* pt_regs */
la ra, ret_from_exception
tail syscall_exit_to_user_mode
SYM_CODE_END(ret_from_kernel_thread)
/*
* Integer register context switch
* The callee-saved registers must be saved and restored.

5
arch/riscv/kernel/process.c
View file

@ -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;
}