1 files changed, 190 insertions, 0 deletions
diff --git a/arch/hexagon/kernel/process.c b/arch/hexagon/kernel/process.c
new file mode 100644
index 000000000..c61165c99
--- /dev/null
+++ b/arch/hexagon/kernel/process.c
@@ -0,0 +1,190 @@
+// 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);
+}