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-rw-r--r--arch/hexagon/kernel/process.c213
1 files changed, 213 insertions, 0 deletions
diff --git a/arch/hexagon/kernel/process.c b/arch/hexagon/kernel/process.c
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+++ b/arch/hexagon/kernel/process.c
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+/*
+ * Process creation support for Hexagon
+ *
+ * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#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 */
+ 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)
+{
+ 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)) {
+ 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 = childregs->r04;
+
+ /*
+ * 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;
+}
+
+/*
+ * Required placeholder.
+ */
+int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
+{
+ 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) {
+ do_signal(regs);
+ return 1;
+ }
+
+ if (thread_info_flags & _TIF_NOTIFY_RESUME) {
+ clear_thread_flag(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);
+}