2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
6 * Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others.
7 * Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org)
8 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
9 * Copyright (C) 2004 Thiemo Seufer
11 #include <linux/errno.h>
12 #include <linux/module.h>
13 #include <linux/sched.h>
14 #include <linux/kernel.h>
16 #include <linux/stddef.h>
17 #include <linux/unistd.h>
18 #include <linux/ptrace.h>
19 #include <linux/slab.h>
20 #include <linux/mman.h>
21 #include <linux/personality.h>
22 #include <linux/sys.h>
23 #include <linux/user.h>
24 #include <linux/a.out.h>
25 #include <linux/init.h>
26 #include <linux/completion.h>
27 #include <linux/kallsyms.h>
28 #include <linux/random.h>
31 #include <asm/bootinfo.h>
35 #include <asm/pgtable.h>
36 #include <asm/system.h>
37 #include <asm/mipsregs.h>
38 #include <asm/processor.h>
39 #include <asm/uaccess.h>
42 #include <asm/isadep.h>
44 #include <asm/stacktrace.h>
47 * The idle thread. There's no useful work to be done, so just try to conserve
48 * power and have a low exit latency (ie sit in a loop waiting for somebody to
49 * say that they'd like to reschedule)
51 void __noreturn
cpu_idle(void)
53 /* endless idle loop with no priority at all */
55 while (!need_resched()) {
56 #ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG
57 extern void smtc_idle_loop_hook(void);
59 smtc_idle_loop_hook();
64 preempt_enable_no_resched();
70 asmlinkage
void ret_from_fork(void);
72 void start_thread(struct pt_regs
* regs
, unsigned long pc
, unsigned long sp
)
76 /* New thread loses kernel privileges. */
77 status
= regs
->cp0_status
& ~(ST0_CU0
|ST0_CU1
|KU_MASK
);
80 status
|= (current
->thread
.mflags
& MF_32BIT_REGS
) ? 0 : ST0_FR
;
83 regs
->cp0_status
= status
;
90 current_thread_info()->addr_limit
= USER_DS
;
93 void exit_thread(void)
97 void flush_thread(void)
101 int copy_thread(int nr
, unsigned long clone_flags
, unsigned long usp
,
102 unsigned long unused
, struct task_struct
*p
, struct pt_regs
*regs
)
104 struct thread_info
*ti
= task_thread_info(p
);
105 struct pt_regs
*childregs
;
107 p
->set_child_tid
= p
->clear_child_tid
= NULL
;
109 childksp
= (unsigned long)task_stack_page(p
) + THREAD_SIZE
- 32;
121 /* set up new TSS. */
122 childregs
= (struct pt_regs
*) childksp
- 1;
124 childregs
->regs
[7] = 0; /* Clear error flag */
126 #if defined(CONFIG_BINFMT_IRIX)
127 if (current
->personality
!= PER_LINUX
) {
128 /* Under IRIX things are a little different. */
129 childregs
->regs
[3] = 1;
133 childregs
->regs
[2] = 0; /* Child gets zero as return value */
134 regs
->regs
[2] = p
->pid
;
136 if (childregs
->cp0_status
& ST0_CU0
) {
137 childregs
->regs
[28] = (unsigned long) ti
;
138 childregs
->regs
[29] = childksp
;
139 ti
->addr_limit
= KERNEL_DS
;
141 childregs
->regs
[29] = usp
;
142 ti
->addr_limit
= USER_DS
;
144 p
->thread
.reg29
= (unsigned long) childregs
;
145 p
->thread
.reg31
= (unsigned long) ret_from_fork
;
148 * New tasks lose permission to use the fpu. This accelerates context
149 * switching for most programs since they don't use the fpu.
151 p
->thread
.cp0_status
= read_c0_status() & ~(ST0_CU2
|ST0_CU1
);
152 childregs
->cp0_status
&= ~(ST0_CU2
|ST0_CU1
);
153 clear_tsk_thread_flag(p
, TIF_USEDFPU
);
155 #ifdef CONFIG_MIPS_MT_FPAFF
157 * FPU affinity support is cleaner if we track the
158 * user-visible CPU affinity from the very beginning.
159 * The generic cpus_allowed mask will already have
160 * been copied from the parent before copy_thread
163 p
->thread
.user_cpus_allowed
= p
->cpus_allowed
;
164 #endif /* CONFIG_MIPS_MT_FPAFF */
166 if (clone_flags
& CLONE_SETTLS
)
167 ti
->tp_value
= regs
->regs
[7];
172 /* Fill in the fpu structure for a core dump.. */
173 int dump_fpu(struct pt_regs
*regs
, elf_fpregset_t
*r
)
175 memcpy(r
, ¤t
->thread
.fpu
, sizeof(current
->thread
.fpu
));
180 void elf_dump_regs(elf_greg_t
*gp
, struct pt_regs
*regs
)
184 for (i
= 0; i
< EF_R0
; i
++)
187 for (i
= 1; i
<= 31; i
++)
188 gp
[EF_R0
+ i
] = regs
->regs
[i
];
191 gp
[EF_LO
] = regs
->lo
;
192 gp
[EF_HI
] = regs
->hi
;
193 gp
[EF_CP0_EPC
] = regs
->cp0_epc
;
194 gp
[EF_CP0_BADVADDR
] = regs
->cp0_badvaddr
;
195 gp
[EF_CP0_STATUS
] = regs
->cp0_status
;
196 gp
[EF_CP0_CAUSE
] = regs
->cp0_cause
;
202 int dump_task_regs (struct task_struct
*tsk
, elf_gregset_t
*regs
)
204 elf_dump_regs(*regs
, task_pt_regs(tsk
));
208 int dump_task_fpu (struct task_struct
*t
, elf_fpregset_t
*fpr
)
210 memcpy(fpr
, &t
->thread
.fpu
, sizeof(current
->thread
.fpu
));
216 * Create a kernel thread
218 static void __noreturn
kernel_thread_helper(void *arg
, int (*fn
)(void *))
223 long kernel_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
227 memset(®s
, 0, sizeof(regs
));
229 regs
.regs
[4] = (unsigned long) arg
;
230 regs
.regs
[5] = (unsigned long) fn
;
231 regs
.cp0_epc
= (unsigned long) kernel_thread_helper
;
232 regs
.cp0_status
= read_c0_status();
233 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
234 regs
.cp0_status
&= ~(ST0_KUP
| ST0_IEC
);
235 regs
.cp0_status
|= ST0_IEP
;
237 regs
.cp0_status
|= ST0_EXL
;
240 /* Ok, create the new process.. */
241 return do_fork(flags
| CLONE_VM
| CLONE_UNTRACED
, 0, ®s
, 0, NULL
, NULL
);
247 struct mips_frame_info
{
249 unsigned long func_size
;
254 static inline int is_ra_save_ins(union mips_instruction
*ip
)
256 /* sw / sd $ra, offset($sp) */
257 return (ip
->i_format
.opcode
== sw_op
|| ip
->i_format
.opcode
== sd_op
) &&
258 ip
->i_format
.rs
== 29 &&
259 ip
->i_format
.rt
== 31;
262 static inline int is_jal_jalr_jr_ins(union mips_instruction
*ip
)
264 if (ip
->j_format
.opcode
== jal_op
)
266 if (ip
->r_format
.opcode
!= spec_op
)
268 return ip
->r_format
.func
== jalr_op
|| ip
->r_format
.func
== jr_op
;
271 static inline int is_sp_move_ins(union mips_instruction
*ip
)
273 /* addiu/daddiu sp,sp,-imm */
274 if (ip
->i_format
.rs
!= 29 || ip
->i_format
.rt
!= 29)
276 if (ip
->i_format
.opcode
== addiu_op
|| ip
->i_format
.opcode
== daddiu_op
)
281 static int get_frame_info(struct mips_frame_info
*info
)
283 union mips_instruction
*ip
= info
->func
;
284 unsigned max_insns
= info
->func_size
/ sizeof(union mips_instruction
);
287 info
->pc_offset
= -1;
288 info
->frame_size
= 0;
294 max_insns
= 128U; /* unknown function size */
295 max_insns
= min(128U, max_insns
);
297 for (i
= 0; i
< max_insns
; i
++, ip
++) {
299 if (is_jal_jalr_jr_ins(ip
))
301 if (!info
->frame_size
) {
302 if (is_sp_move_ins(ip
))
303 info
->frame_size
= - ip
->i_format
.simmediate
;
306 if (info
->pc_offset
== -1 && is_ra_save_ins(ip
)) {
308 ip
->i_format
.simmediate
/ sizeof(long);
312 if (info
->frame_size
&& info
->pc_offset
>= 0) /* nested */
314 if (info
->pc_offset
< 0) /* leaf */
316 /* prologue seems boggus... */
321 static struct mips_frame_info schedule_mfi __read_mostly
;
323 static int __init
frame_info_init(void)
325 unsigned long size
= 0;
326 #ifdef CONFIG_KALLSYMS
329 kallsyms_lookup_size_offset((unsigned long)schedule
, &size
, &ofs
);
331 schedule_mfi
.func
= schedule
;
332 schedule_mfi
.func_size
= size
;
334 get_frame_info(&schedule_mfi
);
337 * Without schedule() frame info, result given by
338 * thread_saved_pc() and get_wchan() are not reliable.
340 if (schedule_mfi
.pc_offset
< 0)
341 printk("Can't analyze schedule() prologue at %p\n", schedule
);
346 arch_initcall(frame_info_init
);
349 * Return saved PC of a blocked thread.
351 unsigned long thread_saved_pc(struct task_struct
*tsk
)
353 struct thread_struct
*t
= &tsk
->thread
;
355 /* New born processes are a special case */
356 if (t
->reg31
== (unsigned long) ret_from_fork
)
358 if (schedule_mfi
.pc_offset
< 0)
360 return ((unsigned long *)t
->reg29
)[schedule_mfi
.pc_offset
];
364 #ifdef CONFIG_KALLSYMS
365 /* used by show_backtrace() */
366 unsigned long unwind_stack(struct task_struct
*task
, unsigned long *sp
,
367 unsigned long pc
, unsigned long *ra
)
369 unsigned long stack_page
;
370 struct mips_frame_info info
;
371 unsigned long size
, ofs
;
373 extern void ret_from_irq(void);
374 extern void ret_from_exception(void);
376 stack_page
= (unsigned long)task_stack_page(task
);
381 * If we reached the bottom of interrupt context,
382 * return saved pc in pt_regs.
384 if (pc
== (unsigned long)ret_from_irq
||
385 pc
== (unsigned long)ret_from_exception
) {
386 struct pt_regs
*regs
;
387 if (*sp
>= stack_page
&&
388 *sp
+ sizeof(*regs
) <= stack_page
+ THREAD_SIZE
- 32) {
389 regs
= (struct pt_regs
*)*sp
;
391 if (__kernel_text_address(pc
)) {
392 *sp
= regs
->regs
[29];
393 *ra
= regs
->regs
[31];
399 if (!kallsyms_lookup_size_offset(pc
, &size
, &ofs
))
402 * Return ra if an exception occured at the first instruction
404 if (unlikely(ofs
== 0)) {
410 info
.func
= (void *)(pc
- ofs
);
411 info
.func_size
= ofs
; /* analyze from start to ofs */
412 leaf
= get_frame_info(&info
);
416 if (*sp
< stack_page
||
417 *sp
+ info
.frame_size
> stack_page
+ THREAD_SIZE
- 32)
422 * For some extreme cases, get_frame_info() can
423 * consider wrongly a nested function as a leaf
424 * one. In that cases avoid to return always the
427 pc
= pc
!= *ra
? *ra
: 0;
429 pc
= ((unsigned long *)(*sp
))[info
.pc_offset
];
431 *sp
+= info
.frame_size
;
433 return __kernel_text_address(pc
) ? pc
: 0;
438 * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
440 unsigned long get_wchan(struct task_struct
*task
)
442 unsigned long pc
= 0;
443 #ifdef CONFIG_KALLSYMS
445 unsigned long ra
= 0;
448 if (!task
|| task
== current
|| task
->state
== TASK_RUNNING
)
450 if (!task_stack_page(task
))
453 pc
= thread_saved_pc(task
);
455 #ifdef CONFIG_KALLSYMS
456 sp
= task
->thread
.reg29
+ schedule_mfi
.frame_size
;
458 while (in_sched_functions(pc
))
459 pc
= unwind_stack(task
, &sp
, pc
, &ra
);
467 * Don't forget that the stack pointer must be aligned on a 8 bytes
468 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
470 unsigned long arch_align_stack(unsigned long sp
)
472 if (!(current
->personality
& ADDR_NO_RANDOMIZE
) && randomize_va_space
)
473 sp
-= get_random_int() & ~PAGE_MASK
;