1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
|
/*
* Process creation support for Hexagon
*
* Copyright (c) 2010-2012, Code Aurora Forum. 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/types.h>
#include <linux/module.h>
#include <linux/tick.h>
#include <linux/uaccess.h>
#include <linux/slab.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)
{
/* Set to run with user-mode data segmentation */
set_fs(USER_DS);
/* 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.
*/
static void default_idle(void)
{
__vmwait();
}
void (*idle_sleep)(void) = default_idle;
void cpu_idle(void)
{
while (1) {
tick_nohz_idle_enter();
local_irq_disable();
while (!need_resched()) {
idle_sleep();
/* interrupts wake us up, but aren't serviced */
local_irq_enable(); /* service interrupt */
local_irq_disable();
}
local_irq_enable();
tick_nohz_idle_exit();
schedule();
}
}
/*
* Return saved PC of a blocked thread
*/
unsigned long thread_saved_pc(struct task_struct *tsk)
{
return 0;
}
/*
* Copy architecture-specific thread state
*/
int copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long arg, struct task_struct *p,
struct pt_regs *regs)
{
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->r2524 = usp | ((u64)arg << 32);
pt_set_kmode(childregs);
return 0;
}
memcpy(childregs, regs, sizeof(*childregs));
ss->r2524 = 0;
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)
{
}
/*
* Free any architecture-specific thread data structures, etc.
*/
void exit_thread(void)
{
}
/*
* 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;
}
|
