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/sched.h>
13 #include <linux/tick.h>
14 #include <linux/kernel.h>
16 #include <linux/stddef.h>
17 #include <linux/unistd.h>
18 #include <linux/export.h>
19 #include <linux/ptrace.h>
20 #include <linux/mman.h>
21 #include <linux/personality.h>
22 #include <linux/sys.h>
23 #include <linux/user.h>
24 #include <linux/init.h>
25 #include <linux/completion.h>
26 #include <linux/kallsyms.h>
27 #include <linux/random.h>
30 #include <asm/bootinfo.h>
34 #include <asm/pgtable.h>
35 #include <asm/mipsregs.h>
36 #include <asm/processor.h>
37 #include <asm/uaccess.h>
40 #include <asm/isadep.h>
42 #include <asm/stacktrace.h>
45 * The idle thread. There's no useful work to be done, so just try to conserve
46 * power and have a low exit latency (ie sit in a loop waiting for somebody to
47 * say that they'd like to reschedule)
49 void __noreturn
cpu_idle(void)
53 /* CPU is going idle. */
54 cpu
= smp_processor_id();
56 /* endless idle loop with no priority at all */
58 tick_nohz_idle_enter();
60 while (!need_resched() && cpu_online(cpu
)) {
61 #ifdef CONFIG_MIPS_MT_SMTC
62 extern void smtc_idle_loop_hook(void);
64 smtc_idle_loop_hook();
68 /* Don't trace irqs off for idle */
69 stop_critical_timings();
71 start_critical_timings();
74 #ifdef CONFIG_HOTPLUG_CPU
75 if (!cpu_online(cpu
) && !cpu_isset(cpu
, cpu_callin_map
))
79 tick_nohz_idle_exit();
80 schedule_preempt_disabled();
84 asmlinkage
void ret_from_fork(void);
85 asmlinkage
void ret_from_kernel_thread(void);
87 void start_thread(struct pt_regs
* regs
, unsigned long pc
, unsigned long sp
)
91 /* New thread loses kernel privileges. */
92 status
= regs
->cp0_status
& ~(ST0_CU0
|ST0_CU1
|ST0_FR
|KU_MASK
);
94 status
|= test_thread_flag(TIF_32BIT_REGS
) ? 0 : ST0_FR
;
97 regs
->cp0_status
= status
;
106 void exit_thread(void)
110 void flush_thread(void)
114 int copy_thread(unsigned long clone_flags
, unsigned long usp
,
115 unsigned long arg
, struct task_struct
*p
)
117 struct thread_info
*ti
= task_thread_info(p
);
118 struct pt_regs
*childregs
, *regs
= current_pt_regs();
119 unsigned long childksp
;
120 p
->set_child_tid
= p
->clear_child_tid
= NULL
;
122 childksp
= (unsigned long)task_stack_page(p
) + THREAD_SIZE
- 32;
134 /* set up new TSS. */
135 childregs
= (struct pt_regs
*) childksp
- 1;
136 /* Put the stack after the struct pt_regs. */
137 childksp
= (unsigned long) childregs
;
138 p
->thread
.cp0_status
= read_c0_status() & ~(ST0_CU2
|ST0_CU1
);
139 if (unlikely(p
->flags
& PF_KTHREAD
)) {
140 unsigned long status
= p
->thread
.cp0_status
;
141 memset(childregs
, 0, sizeof(struct pt_regs
));
142 ti
->addr_limit
= KERNEL_DS
;
143 p
->thread
.reg16
= usp
; /* fn */
144 p
->thread
.reg17
= arg
;
145 p
->thread
.reg29
= childksp
;
146 p
->thread
.reg31
= (unsigned long) ret_from_kernel_thread
;
147 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
148 status
= (status
& ~(ST0_KUP
| ST0_IEP
| ST0_IEC
)) |
149 ((status
& (ST0_KUC
| ST0_IEC
)) << 2);
153 childregs
->cp0_status
= status
;
157 childregs
->regs
[7] = 0; /* Clear error flag */
158 childregs
->regs
[2] = 0; /* Child gets zero as return value */
160 childregs
->regs
[29] = usp
;
161 ti
->addr_limit
= USER_DS
;
163 p
->thread
.reg29
= (unsigned long) childregs
;
164 p
->thread
.reg31
= (unsigned long) ret_from_fork
;
167 * New tasks lose permission to use the fpu. This accelerates context
168 * switching for most programs since they don't use the fpu.
170 childregs
->cp0_status
&= ~(ST0_CU2
|ST0_CU1
);
172 #ifdef CONFIG_MIPS_MT_SMTC
174 * SMTC restores TCStatus after Status, and the CU bits
177 childregs
->cp0_tcstatus
&= ~(ST0_CU2
|ST0_CU1
);
179 clear_tsk_thread_flag(p
, TIF_USEDFPU
);
181 #ifdef CONFIG_MIPS_MT_FPAFF
182 clear_tsk_thread_flag(p
, TIF_FPUBOUND
);
183 #endif /* CONFIG_MIPS_MT_FPAFF */
185 if (clone_flags
& CLONE_SETTLS
)
186 ti
->tp_value
= regs
->regs
[7];
191 /* Fill in the fpu structure for a core dump.. */
192 int dump_fpu(struct pt_regs
*regs
, elf_fpregset_t
*r
)
194 memcpy(r
, ¤t
->thread
.fpu
, sizeof(current
->thread
.fpu
));
199 void elf_dump_regs(elf_greg_t
*gp
, struct pt_regs
*regs
)
203 for (i
= 0; i
< EF_R0
; i
++)
206 for (i
= 1; i
<= 31; i
++)
207 gp
[EF_R0
+ i
] = regs
->regs
[i
];
210 gp
[EF_LO
] = regs
->lo
;
211 gp
[EF_HI
] = regs
->hi
;
212 gp
[EF_CP0_EPC
] = regs
->cp0_epc
;
213 gp
[EF_CP0_BADVADDR
] = regs
->cp0_badvaddr
;
214 gp
[EF_CP0_STATUS
] = regs
->cp0_status
;
215 gp
[EF_CP0_CAUSE
] = regs
->cp0_cause
;
221 int dump_task_regs(struct task_struct
*tsk
, elf_gregset_t
*regs
)
223 elf_dump_regs(*regs
, task_pt_regs(tsk
));
227 int dump_task_fpu(struct task_struct
*t
, elf_fpregset_t
*fpr
)
229 memcpy(fpr
, &t
->thread
.fpu
, sizeof(current
->thread
.fpu
));
237 struct mips_frame_info
{
239 unsigned long func_size
;
244 static inline int is_ra_save_ins(union mips_instruction
*ip
)
246 /* sw / sd $ra, offset($sp) */
247 return (ip
->i_format
.opcode
== sw_op
|| ip
->i_format
.opcode
== sd_op
) &&
248 ip
->i_format
.rs
== 29 &&
249 ip
->i_format
.rt
== 31;
252 static inline int is_jal_jalr_jr_ins(union mips_instruction
*ip
)
254 if (ip
->j_format
.opcode
== jal_op
)
256 if (ip
->r_format
.opcode
!= spec_op
)
258 return ip
->r_format
.func
== jalr_op
|| ip
->r_format
.func
== jr_op
;
261 static inline int is_sp_move_ins(union mips_instruction
*ip
)
263 /* addiu/daddiu sp,sp,-imm */
264 if (ip
->i_format
.rs
!= 29 || ip
->i_format
.rt
!= 29)
266 if (ip
->i_format
.opcode
== addiu_op
|| ip
->i_format
.opcode
== daddiu_op
)
271 static int get_frame_info(struct mips_frame_info
*info
)
273 union mips_instruction
*ip
= info
->func
;
274 unsigned max_insns
= info
->func_size
/ sizeof(union mips_instruction
);
277 info
->pc_offset
= -1;
278 info
->frame_size
= 0;
284 max_insns
= 128U; /* unknown function size */
285 max_insns
= min(128U, max_insns
);
287 for (i
= 0; i
< max_insns
; i
++, ip
++) {
289 if (is_jal_jalr_jr_ins(ip
))
291 if (!info
->frame_size
) {
292 if (is_sp_move_ins(ip
))
293 info
->frame_size
= - ip
->i_format
.simmediate
;
296 if (info
->pc_offset
== -1 && is_ra_save_ins(ip
)) {
298 ip
->i_format
.simmediate
/ sizeof(long);
302 if (info
->frame_size
&& info
->pc_offset
>= 0) /* nested */
304 if (info
->pc_offset
< 0) /* leaf */
306 /* prologue seems boggus... */
311 static struct mips_frame_info schedule_mfi __read_mostly
;
313 static int __init
frame_info_init(void)
315 unsigned long size
= 0;
316 #ifdef CONFIG_KALLSYMS
319 kallsyms_lookup_size_offset((unsigned long)schedule
, &size
, &ofs
);
321 schedule_mfi
.func
= schedule
;
322 schedule_mfi
.func_size
= size
;
324 get_frame_info(&schedule_mfi
);
327 * Without schedule() frame info, result given by
328 * thread_saved_pc() and get_wchan() are not reliable.
330 if (schedule_mfi
.pc_offset
< 0)
331 printk("Can't analyze schedule() prologue at %p\n", schedule
);
336 arch_initcall(frame_info_init
);
339 * Return saved PC of a blocked thread.
341 unsigned long thread_saved_pc(struct task_struct
*tsk
)
343 struct thread_struct
*t
= &tsk
->thread
;
345 /* New born processes are a special case */
346 if (t
->reg31
== (unsigned long) ret_from_fork
)
348 if (schedule_mfi
.pc_offset
< 0)
350 return ((unsigned long *)t
->reg29
)[schedule_mfi
.pc_offset
];
354 #ifdef CONFIG_KALLSYMS
355 /* generic stack unwinding function */
356 unsigned long notrace
unwind_stack_by_address(unsigned long stack_page
,
361 struct mips_frame_info info
;
362 unsigned long size
, ofs
;
364 extern void ret_from_irq(void);
365 extern void ret_from_exception(void);
371 * If we reached the bottom of interrupt context,
372 * return saved pc in pt_regs.
374 if (pc
== (unsigned long)ret_from_irq
||
375 pc
== (unsigned long)ret_from_exception
) {
376 struct pt_regs
*regs
;
377 if (*sp
>= stack_page
&&
378 *sp
+ sizeof(*regs
) <= stack_page
+ THREAD_SIZE
- 32) {
379 regs
= (struct pt_regs
*)*sp
;
381 if (__kernel_text_address(pc
)) {
382 *sp
= regs
->regs
[29];
383 *ra
= regs
->regs
[31];
389 if (!kallsyms_lookup_size_offset(pc
, &size
, &ofs
))
392 * Return ra if an exception occurred at the first instruction
394 if (unlikely(ofs
== 0)) {
400 info
.func
= (void *)(pc
- ofs
);
401 info
.func_size
= ofs
; /* analyze from start to ofs */
402 leaf
= get_frame_info(&info
);
406 if (*sp
< stack_page
||
407 *sp
+ info
.frame_size
> stack_page
+ THREAD_SIZE
- 32)
412 * For some extreme cases, get_frame_info() can
413 * consider wrongly a nested function as a leaf
414 * one. In that cases avoid to return always the
417 pc
= pc
!= *ra
? *ra
: 0;
419 pc
= ((unsigned long *)(*sp
))[info
.pc_offset
];
421 *sp
+= info
.frame_size
;
423 return __kernel_text_address(pc
) ? pc
: 0;
425 EXPORT_SYMBOL(unwind_stack_by_address
);
427 /* used by show_backtrace() */
428 unsigned long unwind_stack(struct task_struct
*task
, unsigned long *sp
,
429 unsigned long pc
, unsigned long *ra
)
431 unsigned long stack_page
= (unsigned long)task_stack_page(task
);
432 return unwind_stack_by_address(stack_page
, sp
, pc
, ra
);
437 * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
439 unsigned long get_wchan(struct task_struct
*task
)
441 unsigned long pc
= 0;
442 #ifdef CONFIG_KALLSYMS
444 unsigned long ra
= 0;
447 if (!task
|| task
== current
|| task
->state
== TASK_RUNNING
)
449 if (!task_stack_page(task
))
452 pc
= thread_saved_pc(task
);
454 #ifdef CONFIG_KALLSYMS
455 sp
= task
->thread
.reg29
+ schedule_mfi
.frame_size
;
457 while (in_sched_functions(pc
))
458 pc
= unwind_stack(task
, &sp
, pc
, &ra
);
466 * Don't forget that the stack pointer must be aligned on a 8 bytes
467 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
469 unsigned long arch_align_stack(unsigned long sp
)
471 if (!(current
->personality
& ADDR_NO_RANDOMIZE
) && randomize_va_space
)
472 sp
-= get_random_int() & ~PAGE_MASK
;