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2 * Process creation support for Hexagon
4 * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 and
8 * only version 2 as published by the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
21 #include <linux/sched.h>
22 #include <linux/sched/debug.h>
23 #include <linux/sched/task.h>
24 #include <linux/types.h>
25 #include <linux/module.h>
26 #include <linux/tick.h>
27 #include <linux/uaccess.h>
28 #include <linux/slab.h>
29 #include <linux/tracehook.h>
32 * Program thread launch. Often defined as a macro in processor.h,
33 * but we're shooting for a small footprint and it's not an inner-loop
34 * performance-critical operation.
36 * The Hexagon ABI specifies that R28 is zero'ed before program launch,
37 * so that gets automatically done here. If we ever stop doing that here,
38 * we'll probably want to define the ELF_PLAT_INIT macro.
40 void start_thread(struct pt_regs
*regs
, unsigned long pc
, unsigned long sp
)
42 /* We want to zero all data-containing registers. Is this overkill? */
43 memset(regs
, 0, sizeof(*regs
));
44 /* We might want to also zero all Processor registers here */
45 pt_set_usermode(regs
);
47 pt_set_rte_sp(regs
, sp
);
51 * Spin, or better still, do a hardware or VM wait instruction
52 * If hardware or VM offer wait termination even though interrupts
55 void arch_cpu_idle(void)
58 /* interrupts wake us up, but irqs are still disabled */
63 * Return saved PC of a blocked thread
65 unsigned long thread_saved_pc(struct task_struct
*tsk
)
71 * Copy architecture-specific thread state
73 int copy_thread(unsigned long clone_flags
, unsigned long usp
,
74 unsigned long arg
, struct task_struct
*p
)
76 struct thread_info
*ti
= task_thread_info(p
);
77 struct hexagon_switch_stack
*ss
;
78 struct pt_regs
*childregs
;
79 asmlinkage
void ret_from_fork(void);
81 childregs
= (struct pt_regs
*) (((unsigned long) ti
+ THREAD_SIZE
) -
87 * Establish kernel stack pointer and initial PC for new thread
88 * Note that unlike the usual situation, we do not copy the
89 * parent's callee-saved here; those are in pt_regs and whatever
90 * we leave here will be overridden on return to userland.
92 ss
= (struct hexagon_switch_stack
*) ((unsigned long) childregs
-
94 ss
->lr
= (unsigned long)ret_from_fork
;
95 p
->thread
.switch_sp
= ss
;
96 if (unlikely(p
->flags
& PF_KTHREAD
)) {
97 memset(childregs
, 0, sizeof(struct pt_regs
));
98 /* r24 <- fn, r25 <- arg */
101 pt_set_kmode(childregs
);
104 memcpy(childregs
, current_pt_regs(), sizeof(*childregs
));
108 pt_set_rte_sp(childregs
, usp
);
110 /* Child sees zero return value */
114 * The clone syscall has the C signature:
115 * int [r0] clone(int flags [r0],
116 * void *child_frame [r1],
117 * void *parent_tid [r2],
118 * void *child_tid [r3],
119 * void *thread_control_block [r4]);
120 * ugp is used to provide TLS support.
122 if (clone_flags
& CLONE_SETTLS
)
123 childregs
->ugp
= childregs
->r04
;
126 * Parent sees new pid -- not necessary, not even possible at
127 * this point in the fork process
128 * Might also want to set things like ti->addr_limit
135 * Release any architecture-specific resources locked by thread
137 void release_thread(struct task_struct
*dead_task
)
142 * Some archs flush debug and FPU info here
144 void flush_thread(void)
149 * The "wait channel" terminology is archaic, but what we want
150 * is an identification of the point at which the scheduler
151 * was invoked by a blocked thread.
153 unsigned long get_wchan(struct task_struct
*p
)
155 unsigned long fp
, pc
;
156 unsigned long stack_page
;
158 if (!p
|| p
== current
|| p
->state
== TASK_RUNNING
)
161 stack_page
= (unsigned long)task_stack_page(p
);
162 fp
= ((struct hexagon_switch_stack
*)p
->thread
.switch_sp
)->fp
;
164 if (fp
< (stack_page
+ sizeof(struct thread_info
)) ||
165 fp
>= (THREAD_SIZE
- 8 + stack_page
))
167 pc
= ((unsigned long *)fp
)[1];
168 if (!in_sched_functions(pc
))
170 fp
= *(unsigned long *) fp
;
171 } while (count
++ < 16);
177 * Required placeholder.
179 int dump_fpu(struct pt_regs
*regs
, elf_fpregset_t
*fpu
)
186 * Called on the exit path of event entry; see vm_entry.S
188 * Interrupts will already be disabled.
190 * Returns 0 if there's no need to re-check for more work.
193 int do_work_pending(struct pt_regs
*regs
, u32 thread_info_flags
)
195 if (!(thread_info_flags
& _TIF_WORK_MASK
)) {
197 } /* shortcut -- no work to be done */
201 if (thread_info_flags
& _TIF_NEED_RESCHED
) {
206 if (thread_info_flags
& _TIF_SIGPENDING
) {
211 if (thread_info_flags
& _TIF_NOTIFY_RESUME
) {
212 clear_thread_flag(TIF_NOTIFY_RESUME
);
213 tracehook_notify_resume(regs
);
217 /* Should not even reach here */
218 panic("%s: bad thread_info flags 0x%08x\n", __func__
,