| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * Process creation support for Hexagon |
| * |
| * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved. |
| */ |
| |
| #include <linux/sched.h> |
| #include <linux/sched/debug.h> |
| #include <linux/sched/task.h> |
| #include <linux/sched/task_stack.h> |
| #include <linux/types.h> |
| #include <linux/module.h> |
| #include <linux/tick.h> |
| #include <linux/uaccess.h> |
| #include <linux/slab.h> |
| #include <linux/tracehook.h> |
| |
| /* |
| * Program thread launch. Often defined as a macro in processor.h, |
| * but we're shooting for a small footprint and it's not an inner-loop |
| * performance-critical operation. |
| * |
| * The Hexagon ABI specifies that R28 is zero'ed before program launch, |
| * so that gets automatically done here. If we ever stop doing that here, |
| * we'll probably want to define the ELF_PLAT_INIT macro. |
| */ |
| void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) |
| { |
| /* We want to zero all data-containing registers. Is this overkill? */ |
| memset(regs, 0, sizeof(*regs)); |
| /* We might want to also zero all Processor registers here */ |
| pt_set_usermode(regs); |
| pt_set_elr(regs, pc); |
| pt_set_rte_sp(regs, sp); |
| } |
| |
| /* |
| * Spin, or better still, do a hardware or VM wait instruction |
| * If hardware or VM offer wait termination even though interrupts |
| * are disabled. |
| */ |
| void arch_cpu_idle(void) |
| { |
| __vmwait(); |
| /* interrupts wake us up, but irqs are still disabled */ |
| raw_local_irq_enable(); |
| } |
| |
| /* |
| * Copy architecture-specific thread state |
| */ |
| int copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long arg, |
| struct task_struct *p, unsigned long tls) |
| { |
| struct thread_info *ti = task_thread_info(p); |
| struct hexagon_switch_stack *ss; |
| struct pt_regs *childregs; |
| asmlinkage void ret_from_fork(void); |
| |
| childregs = (struct pt_regs *) (((unsigned long) ti + THREAD_SIZE) - |
| sizeof(*childregs)); |
| |
| ti->regs = childregs; |
| |
| /* |
| * Establish kernel stack pointer and initial PC for new thread |
| * Note that unlike the usual situation, we do not copy the |
| * parent's callee-saved here; those are in pt_regs and whatever |
| * we leave here will be overridden on return to userland. |
| */ |
| ss = (struct hexagon_switch_stack *) ((unsigned long) childregs - |
| sizeof(*ss)); |
| ss->lr = (unsigned long)ret_from_fork; |
| p->thread.switch_sp = ss; |
| if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) { |
| memset(childregs, 0, sizeof(struct pt_regs)); |
| /* r24 <- fn, r25 <- arg */ |
| ss->r24 = usp; |
| ss->r25 = arg; |
| pt_set_kmode(childregs); |
| return 0; |
| } |
| memcpy(childregs, current_pt_regs(), sizeof(*childregs)); |
| ss->r2524 = 0; |
| |
| if (usp) |
| pt_set_rte_sp(childregs, usp); |
| |
| /* Child sees zero return value */ |
| childregs->r00 = 0; |
| |
| /* |
| * The clone syscall has the C signature: |
| * int [r0] clone(int flags [r0], |
| * void *child_frame [r1], |
| * void *parent_tid [r2], |
| * void *child_tid [r3], |
| * void *thread_control_block [r4]); |
| * ugp is used to provide TLS support. |
| */ |
| if (clone_flags & CLONE_SETTLS) |
| childregs->ugp = tls; |
| |
| /* |
| * Parent sees new pid -- not necessary, not even possible at |
| * this point in the fork process |
| * Might also want to set things like ti->addr_limit |
| */ |
| |
| return 0; |
| } |
| |
| /* |
| * Release any architecture-specific resources locked by thread |
| */ |
| void release_thread(struct task_struct *dead_task) |
| { |
| } |
| |
| /* |
| * Some archs flush debug and FPU info here |
| */ |
| void flush_thread(void) |
| { |
| } |
| |
| /* |
| * The "wait channel" terminology is archaic, but what we want |
| * is an identification of the point at which the scheduler |
| * was invoked by a blocked thread. |
| */ |
| unsigned long get_wchan(struct task_struct *p) |
| { |
| unsigned long fp, pc; |
| unsigned long stack_page; |
| int count = 0; |
| if (!p || p == current || p->state == TASK_RUNNING) |
| return 0; |
| |
| stack_page = (unsigned long)task_stack_page(p); |
| fp = ((struct hexagon_switch_stack *)p->thread.switch_sp)->fp; |
| do { |
| if (fp < (stack_page + sizeof(struct thread_info)) || |
| fp >= (THREAD_SIZE - 8 + stack_page)) |
| return 0; |
| pc = ((unsigned long *)fp)[1]; |
| if (!in_sched_functions(pc)) |
| return pc; |
| fp = *(unsigned long *) fp; |
| } while (count++ < 16); |
| |
| return 0; |
| } |
| |
| /* |
| * Called on the exit path of event entry; see vm_entry.S |
| * |
| * Interrupts will already be disabled. |
| * |
| * Returns 0 if there's no need to re-check for more work. |
| */ |
| |
| int do_work_pending(struct pt_regs *regs, u32 thread_info_flags) |
| { |
| if (!(thread_info_flags & _TIF_WORK_MASK)) { |
| return 0; |
| } /* shortcut -- no work to be done */ |
| |
| local_irq_enable(); |
| |
| if (thread_info_flags & _TIF_NEED_RESCHED) { |
| schedule(); |
| return 1; |
| } |
| |
| if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) { |
| do_signal(regs); |
| return 1; |
| } |
| |
| if (thread_info_flags & _TIF_NOTIFY_RESUME) { |
| tracehook_notify_resume(regs); |
| return 1; |
| } |
| |
| /* Should not even reach here */ |
| panic("%s: bad thread_info flags 0x%08x\n", __func__, |
| thread_info_flags); |
| } |