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
10 * Copyright (C) 2013 Imagination Technologies Ltd.
12 #include <linux/errno.h>
13 #include <linux/sched.h>
14 #include <linux/tick.h>
15 #include <linux/kernel.h>
17 #include <linux/stddef.h>
18 #include <linux/unistd.h>
19 #include <linux/export.h>
20 #include <linux/ptrace.h>
21 #include <linux/mman.h>
22 #include <linux/personality.h>
23 #include <linux/sys.h>
24 #include <linux/init.h>
25 #include <linux/completion.h>
26 #include <linux/kallsyms.h>
27 #include <linux/random.h>
28 #include <linux/prctl.h>
31 #include <asm/bootinfo.h>
36 #include <asm/pgtable.h>
37 #include <asm/mipsregs.h>
38 #include <asm/processor.h>
40 #include <asm/uaccess.h>
43 #include <asm/isadep.h>
45 #include <asm/stacktrace.h>
46 #include <asm/irq_regs.h>
48 #ifdef CONFIG_HOTPLUG_CPU
49 void arch_cpu_idle_dead(void)
51 /* What the heck is this check doing ? */
52 if (!cpumask_test_cpu(smp_processor_id(), &cpu_callin_map))
57 asmlinkage void ret_from_fork(void);
58 asmlinkage void ret_from_kernel_thread(void);
60 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
64 /* New thread loses kernel privileges. */
65 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
67 regs->cp0_status = status;
69 clear_thread_flag(TIF_MSA_CTX_LIVE);
76 void exit_thread(void)
80 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
83 * Save any process state which is live in hardware registers to the
84 * parent context prior to duplication. This prevents the new child
85 * state becoming stale if the parent is preempted before copy_thread()
86 * gets a chance to save the parent's live hardware registers to the
93 else if (is_fpu_owner())
105 * Copy architecture-specific thread state
107 int copy_thread(unsigned long clone_flags, unsigned long usp,
108 unsigned long kthread_arg, struct task_struct *p)
110 struct thread_info *ti = task_thread_info(p);
111 struct pt_regs *childregs, *regs = current_pt_regs();
112 unsigned long childksp;
113 p->set_child_tid = p->clear_child_tid = NULL;
115 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
117 /* set up new TSS. */
118 childregs = (struct pt_regs *) childksp - 1;
119 /* Put the stack after the struct pt_regs. */
120 childksp = (unsigned long) childregs;
121 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
122 if (unlikely(p->flags & PF_KTHREAD)) {
124 unsigned long status = p->thread.cp0_status;
125 memset(childregs, 0, sizeof(struct pt_regs));
126 ti->addr_limit = KERNEL_DS;
127 p->thread.reg16 = usp; /* fn */
128 p->thread.reg17 = kthread_arg;
129 p->thread.reg29 = childksp;
130 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
131 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
132 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
133 ((status & (ST0_KUC | ST0_IEC)) << 2);
137 childregs->cp0_status = status;
143 childregs->regs[7] = 0; /* Clear error flag */
144 childregs->regs[2] = 0; /* Child gets zero as return value */
146 childregs->regs[29] = usp;
147 ti->addr_limit = USER_DS;
149 p->thread.reg29 = (unsigned long) childregs;
150 p->thread.reg31 = (unsigned long) ret_from_fork;
153 * New tasks lose permission to use the fpu. This accelerates context
154 * switching for most programs since they don't use the fpu.
156 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
158 clear_tsk_thread_flag(p, TIF_USEDFPU);
159 clear_tsk_thread_flag(p, TIF_USEDMSA);
160 clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
162 #ifdef CONFIG_MIPS_MT_FPAFF
163 clear_tsk_thread_flag(p, TIF_FPUBOUND);
164 #endif /* CONFIG_MIPS_MT_FPAFF */
166 if (clone_flags & CLONE_SETTLS)
167 ti->tp_value = regs->regs[7];
172 #ifdef CONFIG_CC_STACKPROTECTOR
173 #include <linux/stackprotector.h>
174 unsigned long __stack_chk_guard __read_mostly;
175 EXPORT_SYMBOL(__stack_chk_guard);
178 struct mips_frame_info {
180 unsigned long func_size;
185 #define J_TARGET(pc,target) \
186 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
188 static inline int is_ra_save_ins(union mips_instruction *ip)
190 #ifdef CONFIG_CPU_MICROMIPS
191 union mips_instruction mmi;
195 * swm16 reglist,offset(sp)
196 * swm32 reglist,offset(sp)
198 * jradiussp - NOT SUPPORTED
200 * microMIPS is way more fun...
202 if (mm_insn_16bit(ip->halfword[0])) {
203 mmi.word = (ip->halfword[0] << 16);
204 return (mmi.mm16_r5_format.opcode == mm_swsp16_op &&
205 mmi.mm16_r5_format.rt == 31) ||
206 (mmi.mm16_m_format.opcode == mm_pool16c_op &&
207 mmi.mm16_m_format.func == mm_swm16_op);
210 mmi.halfword[0] = ip->halfword[1];
211 mmi.halfword[1] = ip->halfword[0];
212 return (mmi.mm_m_format.opcode == mm_pool32b_op &&
213 mmi.mm_m_format.rd > 9 &&
214 mmi.mm_m_format.base == 29 &&
215 mmi.mm_m_format.func == mm_swm32_func) ||
216 (mmi.i_format.opcode == mm_sw32_op &&
217 mmi.i_format.rs == 29 &&
218 mmi.i_format.rt == 31);
221 /* sw / sd $ra, offset($sp) */
222 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
223 ip->i_format.rs == 29 &&
224 ip->i_format.rt == 31;
228 static inline int is_jump_ins(union mips_instruction *ip)
230 #ifdef CONFIG_CPU_MICROMIPS
232 * jr16,jrc,jalr16,jalr16
234 * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
235 * jraddiusp - NOT SUPPORTED
237 * microMIPS is kind of more fun...
239 union mips_instruction mmi;
241 mmi.word = (ip->halfword[0] << 16);
243 if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
244 (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
245 ip->j_format.opcode == mm_jal32_op)
247 if (ip->r_format.opcode != mm_pool32a_op ||
248 ip->r_format.func != mm_pool32axf_op)
250 return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
252 if (ip->j_format.opcode == j_op)
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;
262 static inline int is_sp_move_ins(union mips_instruction *ip)
264 #ifdef CONFIG_CPU_MICROMIPS
269 * jradiussp - NOT SUPPORTED
271 * microMIPS is not more fun...
273 if (mm_insn_16bit(ip->halfword[0])) {
274 union mips_instruction mmi;
276 mmi.word = (ip->halfword[0] << 16);
277 return (mmi.mm16_r3_format.opcode == mm_pool16d_op &&
278 mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
279 (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
280 mmi.mm16_r5_format.rt == 29);
282 return ip->mm_i_format.opcode == mm_addiu32_op &&
283 ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29;
285 /* addiu/daddiu sp,sp,-imm */
286 if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
288 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
294 static int get_frame_info(struct mips_frame_info *info)
296 #ifdef CONFIG_CPU_MICROMIPS
297 union mips_instruction *ip = (void *) (((char *) info->func) - 1);
299 union mips_instruction *ip = info->func;
301 unsigned max_insns = info->func_size / sizeof(union mips_instruction);
304 info->pc_offset = -1;
305 info->frame_size = 0;
311 max_insns = 128U; /* unknown function size */
312 max_insns = min(128U, max_insns);
314 for (i = 0; i < max_insns; i++, ip++) {
318 if (!info->frame_size) {
319 if (is_sp_move_ins(ip))
321 #ifdef CONFIG_CPU_MICROMIPS
322 if (mm_insn_16bit(ip->halfword[0]))
326 if (ip->halfword[0] & mm_addiusp_func)
328 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
329 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
331 tmp = (ip->halfword[0] >> 1);
332 info->frame_size = -(signed short)(tmp & 0xf);
334 ip = (void *) &ip->halfword[1];
338 info->frame_size = - ip->i_format.simmediate;
342 if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
344 ip->i_format.simmediate / sizeof(long);
348 if (info->frame_size && info->pc_offset >= 0) /* nested */
350 if (info->pc_offset < 0) /* leaf */
352 /* prologue seems boggus... */
357 static struct mips_frame_info schedule_mfi __read_mostly;
359 #ifdef CONFIG_KALLSYMS
360 static unsigned long get___schedule_addr(void)
362 return kallsyms_lookup_name("__schedule");
365 static unsigned long get___schedule_addr(void)
367 union mips_instruction *ip = (void *)schedule;
371 for (i = 0; i < max_insns; i++, ip++) {
372 if (ip->j_format.opcode == j_op)
373 return J_TARGET(ip, ip->j_format.target);
379 static int __init frame_info_init(void)
381 unsigned long size = 0;
382 #ifdef CONFIG_KALLSYMS
387 addr = get___schedule_addr();
389 addr = (unsigned long)schedule;
391 #ifdef CONFIG_KALLSYMS
392 kallsyms_lookup_size_offset(addr, &size, &ofs);
394 schedule_mfi.func = (void *)addr;
395 schedule_mfi.func_size = size;
397 get_frame_info(&schedule_mfi);
400 * Without schedule() frame info, result given by
401 * thread_saved_pc() and get_wchan() are not reliable.
403 if (schedule_mfi.pc_offset < 0)
404 printk("Can't analyze schedule() prologue at %p\n", schedule);
409 arch_initcall(frame_info_init);
412 * Return saved PC of a blocked thread.
414 unsigned long thread_saved_pc(struct task_struct *tsk)
416 struct thread_struct *t = &tsk->thread;
418 /* New born processes are a special case */
419 if (t->reg31 == (unsigned long) ret_from_fork)
421 if (schedule_mfi.pc_offset < 0)
423 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
427 #ifdef CONFIG_KALLSYMS
428 /* generic stack unwinding function */
429 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
434 struct mips_frame_info info;
435 unsigned long size, ofs;
437 extern void ret_from_irq(void);
438 extern void ret_from_exception(void);
444 * If we reached the bottom of interrupt context,
445 * return saved pc in pt_regs.
447 if (pc == (unsigned long)ret_from_irq ||
448 pc == (unsigned long)ret_from_exception) {
449 struct pt_regs *regs;
450 if (*sp >= stack_page &&
451 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
452 regs = (struct pt_regs *)*sp;
454 if (!user_mode(regs) && __kernel_text_address(pc)) {
455 *sp = regs->regs[29];
456 *ra = regs->regs[31];
462 if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
465 * Return ra if an exception occurred at the first instruction
467 if (unlikely(ofs == 0)) {
473 info.func = (void *)(pc - ofs);
474 info.func_size = ofs; /* analyze from start to ofs */
475 leaf = get_frame_info(&info);
479 if (*sp < stack_page ||
480 *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
485 * For some extreme cases, get_frame_info() can
486 * consider wrongly a nested function as a leaf
487 * one. In that cases avoid to return always the
490 pc = pc != *ra ? *ra : 0;
492 pc = ((unsigned long *)(*sp))[info.pc_offset];
494 *sp += info.frame_size;
496 return __kernel_text_address(pc) ? pc : 0;
498 EXPORT_SYMBOL(unwind_stack_by_address);
500 /* used by show_backtrace() */
501 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
502 unsigned long pc, unsigned long *ra)
504 unsigned long stack_page = (unsigned long)task_stack_page(task);
505 return unwind_stack_by_address(stack_page, sp, pc, ra);
510 * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
512 unsigned long get_wchan(struct task_struct *task)
514 unsigned long pc = 0;
515 #ifdef CONFIG_KALLSYMS
517 unsigned long ra = 0;
520 if (!task || task == current || task->state == TASK_RUNNING)
522 if (!task_stack_page(task))
525 pc = thread_saved_pc(task);
527 #ifdef CONFIG_KALLSYMS
528 sp = task->thread.reg29 + schedule_mfi.frame_size;
530 while (in_sched_functions(pc))
531 pc = unwind_stack(task, &sp, pc, &ra);
539 * Don't forget that the stack pointer must be aligned on a 8 bytes
540 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
542 unsigned long arch_align_stack(unsigned long sp)
544 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
545 sp -= get_random_int() & ~PAGE_MASK;
550 static void arch_dump_stack(void *info)
552 struct pt_regs *regs;
554 regs = get_irq_regs();
562 void arch_trigger_all_cpu_backtrace(bool include_self)
564 smp_call_function(arch_dump_stack, NULL, 1);
567 int mips_get_process_fp_mode(struct task_struct *task)
571 if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
572 value |= PR_FP_MODE_FR;
573 if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
574 value |= PR_FP_MODE_FRE;
579 static void prepare_for_fp_mode_switch(void *info)
581 struct mm_struct *mm = info;
583 if (current->mm == mm)
587 int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
589 const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
590 struct task_struct *t;
593 /* Check the value is valid */
594 if (value & ~known_bits)
597 /* Avoid inadvertently triggering emulation */
598 if ((value & PR_FP_MODE_FR) && cpu_has_fpu &&
599 !(current_cpu_data.fpu_id & MIPS_FPIR_F64))
601 if ((value & PR_FP_MODE_FRE) && cpu_has_fpu && !cpu_has_fre)
604 /* FR = 0 not supported in MIPS R6 */
605 if (!(value & PR_FP_MODE_FR) && cpu_has_fpu && cpu_has_mips_r6)
608 /* Proceed with the mode switch */
611 /* Save FP & vector context, then disable FPU & MSA */
612 if (task->signal == current->signal)
615 /* Prevent any threads from obtaining live FP context */
616 atomic_set(&task->mm->context.fp_mode_switching, 1);
617 smp_mb__after_atomic();
620 * If there are multiple online CPUs then force any which are running
621 * threads in this process to lose their FPU context, which they can't
622 * regain until fp_mode_switching is cleared later.
624 if (num_online_cpus() > 1) {
625 /* No need to send an IPI for the local CPU */
626 max_users = (task->mm == current->mm) ? 1 : 0;
628 if (atomic_read(¤t->mm->mm_users) > max_users)
629 smp_call_function(prepare_for_fp_mode_switch,
630 (void *)current->mm, 1);
634 * There are now no threads of the process with live FP context, so it
635 * is safe to proceed with the FP mode switch.
637 for_each_thread(task, t) {
638 /* Update desired FP register width */
639 if (value & PR_FP_MODE_FR) {
640 clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
642 set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
643 clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
646 /* Update desired FP single layout */
647 if (value & PR_FP_MODE_FRE)
648 set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
650 clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
653 /* Allow threads to use FP again */
654 atomic_set(&task->mm->context.fp_mode_switching, 0);