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Diffstat (limited to 'arch/hexagon/kernel/process.c')
| -rw-r--r-- | arch/hexagon/kernel/process.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/arch/hexagon/kernel/process.c b/arch/hexagon/kernel/process.c new file mode 100644 index 000000000..e15eeaebd --- /dev/null +++ b/arch/hexagon/kernel/process.c @@ -0,0 +1,182 @@ +// 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/resume_user_mode.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(struct task_struct *p, const struct kernel_clone_args *args) +{ + unsigned long clone_flags = args->flags; + unsigned long usp = args->stack; + unsigned long tls = args->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(args->fn)) { + memset(childregs, 0, sizeof(struct pt_regs)); + /* r24 <- fn, r25 <- arg */ + ss->r24 = (unsigned long)args->fn; + ss->r25 = (unsigned long)args->fn_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 + */ + + return 0; +} + +/* + * 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; + + 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) { + resume_user_mode_work(regs); + return 1; + } + + /* Should not even reach here */ + panic("%s: bad thread_info flags 0x%08x\n", __func__, + thread_info_flags); +} |