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
205
206
207
208
209
210
|
/*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Amit Bhor, Kanika Nema: Codito Technologies 2004
*/
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
#include <linux/elf.h>
#include <linux/tick.h>
SYSCALL_DEFINE1(arc_settls, void *, user_tls_data_ptr)
{
task_thread_info(current)->thr_ptr = (unsigned int)user_tls_data_ptr;
return 0;
}
/*
* We return the user space TLS data ptr as sys-call return code
* Ideally it should be copy to user.
* However we can cheat by the fact that some sys-calls do return
* absurdly high values
* Since the tls dat aptr is not going to be in range of 0xFFFF_xxxx
* it won't be considered a sys-call error
* and it will be loads better than copy-to-user, which is a definite
* D-TLB Miss
*/
SYSCALL_DEFINE0(arc_gettls)
{
return task_thread_info(current)->thr_ptr;
}
void arch_cpu_idle(void)
{
/* sleep, but enable all interrupts before committing */
__asm__("sleep 0x3");
}
asmlinkage void ret_from_fork(void);
/* Layout of Child kernel mode stack as setup at the end of this function is
*
* | ... |
* | ... |
* | unused |
* | |
* ------------------ <==== top of Stack (thread.ksp)
* | UNUSED 1 word|
* ------------------
* | r25 |
* ~ ~
* | --to-- | (CALLEE Regs of user mode)
* | r13 |
* ------------------
* | fp |
* | blink | @ret_from_fork
* ------------------
* | |
* ~ ~
* ~ ~
* | |
* ------------------
* | r12 |
* ~ ~
* | --to-- | (scratch Regs of user mode)
* | r0 |
* ------------------
* | UNUSED 1 word|
* ------------------ <===== END of PAGE
*/
int copy_thread(unsigned long clone_flags,
unsigned long usp, unsigned long arg,
struct task_struct *p)
{
struct pt_regs *c_regs; /* child's pt_regs */
unsigned long *childksp; /* to unwind out of __switch_to() */
struct callee_regs *c_callee; /* child's callee regs */
struct callee_regs *parent_callee; /* paren't callee */
struct pt_regs *regs = current_pt_regs();
/* Mark the specific anchors to begin with (see pic above) */
c_regs = task_pt_regs(p);
childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */
c_callee = ((struct callee_regs *)childksp) - 1;
/*
* __switch_to() uses thread.ksp to start unwinding stack
* For kernel threads we don't need to create callee regs, the
* stack layout nevertheless needs to remain the same.
* Also, since __switch_to anyways unwinds callee regs, we use
* this to populate kernel thread entry-pt/args into callee regs,
* so that ret_from_kernel_thread() becomes simpler.
*/
p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */
/* __switch_to expects FP(0), BLINK(return addr) at top */
childksp[0] = 0; /* fp */
childksp[1] = (unsigned long)ret_from_fork; /* blink */
if (unlikely(p->flags & PF_KTHREAD)) {
memset(c_regs, 0, sizeof(struct pt_regs));
c_callee->r13 = arg; /* argument to kernel thread */
c_callee->r14 = usp; /* function */
return 0;
}
/*--------- User Task Only --------------*/
/* __switch_to expects FP(0), BLINK(return addr) at top of stack */
childksp[0] = 0; /* for POP fp */
childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */
/* Copy parents pt regs on child's kernel mode stack */
*c_regs = *regs;
if (usp)
c_regs->sp = usp;
c_regs->r0 = 0; /* fork returns 0 in child */
parent_callee = ((struct callee_regs *)regs) - 1;
*c_callee = *parent_callee;
if (unlikely(clone_flags & CLONE_SETTLS)) {
/*
* set task's userland tls data ptr from 4th arg
* clone C-lib call is difft from clone sys-call
*/
task_thread_info(p)->thr_ptr = regs->r3;
} else {
/* Normal fork case: set parent's TLS ptr in child */
task_thread_info(p)->thr_ptr =
task_thread_info(current)->thr_ptr;
}
return 0;
}
/*
* Some archs flush debug and FPU info here
*/
void flush_thread(void)
{
}
/*
* Free any architecture-specific thread data structures, etc.
*/
void exit_thread(void)
{
}
int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
{
return 0;
}
/*
* API: expected by schedular Code: If thread is sleeping where is that.
* What is this good for? it will be always the scheduler or ret_from_fork.
* So we hard code that anyways.
*/
unsigned long thread_saved_pc(struct task_struct *t)
{
struct pt_regs *regs = task_pt_regs(t);
unsigned long blink = 0;
/*
* If the thread being queried for in not itself calling this, then it
* implies it is not executing, which in turn implies it is sleeping,
* which in turn implies it got switched OUT by the schedular.
* In that case, it's kernel mode blink can reliably retrieved as per
* the picture above (right above pt_regs).
*/
if (t != current && t->state != TASK_RUNNING)
blink = *((unsigned int *)regs - 1);
return blink;
}
int elf_check_arch(const struct elf32_hdr *x)
{
unsigned int eflags;
if (x->e_machine != EM_ARCOMPACT)
return 0;
eflags = x->e_flags;
if ((eflags & EF_ARC_OSABI_MSK) < EF_ARC_OSABI_CURRENT) {
pr_err("ABI mismatch - you need newer toolchain\n");
force_sigsegv(SIGSEGV, current);
return 0;
}
return 1;
}
EXPORT_SYMBOL(elf_check_arch);
|
