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;
71 clear_thread_flag(TIF_USEDMSA);
72 clear_thread_flag(TIF_MSA_CTX_LIVE);
78 void exit_thread(void)
82 void flush_thread(void)
86 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
89 * Save any process state which is live in hardware registers to the
90 * parent context prior to duplication. This prevents the new child
91 * state becoming stale if the parent is preempted before copy_thread()
92 * gets a chance to save the parent's live hardware registers to the
99 else if (is_fpu_owner())
111 * Copy architecture-specific thread state
113 int copy_thread(unsigned long clone_flags, unsigned long usp,
114 unsigned long kthread_arg, struct task_struct *p)
116 struct thread_info *ti = task_thread_info(p);
117 struct pt_regs *childregs, *regs = current_pt_regs();
118 unsigned long childksp;
119 p->set_child_tid = p->clear_child_tid = NULL;
121 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
123 /* set up new TSS. */
124 childregs = (struct pt_regs *) childksp - 1;
125 /* Put the stack after the struct pt_regs. */
126 childksp = (unsigned long) childregs;
127 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
128 if (unlikely(p->flags & PF_KTHREAD)) {
130 unsigned long status = p->thread.cp0_status;
131 memset(childregs, 0, sizeof(struct pt_regs));
132 ti->addr_limit = KERNEL_DS;
133 p->thread.reg16 = usp; /* fn */
134 p->thread.reg17 = kthread_arg;
135 p->thread.reg29 = childksp;
136 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
137 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
138 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
139 ((status & (ST0_KUC | ST0_IEC)) << 2);
143 childregs->cp0_status = status;
149 childregs->regs[7] = 0; /* Clear error flag */
150 childregs->regs[2] = 0; /* Child gets zero as return value */
152 childregs->regs[29] = usp;
153 ti->addr_limit = USER_DS;
155 p->thread.reg29 = (unsigned long) childregs;
156 p->thread.reg31 = (unsigned long) ret_from_fork;
159 * New tasks lose permission to use the fpu. This accelerates context
160 * switching for most programs since they don't use the fpu.
162 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
164 clear_tsk_thread_flag(p, TIF_USEDFPU);
165 clear_tsk_thread_flag(p, TIF_USEDMSA);
166 clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
168 #ifdef CONFIG_MIPS_MT_FPAFF
169 clear_tsk_thread_flag(p, TIF_FPUBOUND);
170 #endif /* CONFIG_MIPS_MT_FPAFF */
172 if (clone_flags & CLONE_SETTLS)
173 ti->tp_value = regs->regs[7];
178 #ifdef CONFIG_CC_STACKPROTECTOR
179 #include <linux/stackprotector.h>
180 unsigned long __stack_chk_guard __read_mostly;
181 EXPORT_SYMBOL(__stack_chk_guard);
184 struct mips_frame_info {
186 unsigned long func_size;
191 #define J_TARGET(pc,target) \
192 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
194 static inline int is_ra_save_ins(union mips_instruction *ip)
196 #ifdef CONFIG_CPU_MICROMIPS
199 * swm16 reglist,offset(sp)
200 * swm32 reglist,offset(sp)
202 * jradiussp - NOT SUPPORTED
204 * microMIPS is way more fun...
206 if (mm_insn_16bit(ip->halfword[1])) {
207 return (ip->mm16_r5_format.opcode == mm_swsp16_op &&
208 ip->mm16_r5_format.rt == 31) ||
209 (ip->mm16_m_format.opcode == mm_pool16c_op &&
210 ip->mm16_m_format.func == mm_swm16_op);
213 return (ip->mm_m_format.opcode == mm_pool32b_op &&
214 ip->mm_m_format.rd > 9 &&
215 ip->mm_m_format.base == 29 &&
216 ip->mm_m_format.func == mm_swm32_func) ||
217 (ip->i_format.opcode == mm_sw32_op &&
218 ip->i_format.rs == 29 &&
219 ip->i_format.rt == 31);
222 /* sw / sd $ra, offset($sp) */
223 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
224 ip->i_format.rs == 29 &&
225 ip->i_format.rt == 31;
229 static inline int is_jump_ins(union mips_instruction *ip)
231 #ifdef CONFIG_CPU_MICROMIPS
233 * jr16,jrc,jalr16,jalr16
235 * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
236 * jraddiusp - NOT SUPPORTED
238 * microMIPS is kind of more fun...
240 if ((ip->mm16_r5_format.opcode == mm_pool16c_op &&
241 (ip->mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
242 ip->j_format.opcode == mm_jal32_op)
244 if (ip->r_format.opcode != mm_pool32a_op ||
245 ip->r_format.func != mm_pool32axf_op)
247 return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
249 if (ip->j_format.opcode == j_op)
251 if (ip->j_format.opcode == jal_op)
253 if (ip->r_format.opcode != spec_op)
255 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
259 static inline int is_sp_move_ins(union mips_instruction *ip)
261 #ifdef CONFIG_CPU_MICROMIPS
266 * jradiussp - NOT SUPPORTED
268 * microMIPS is not more fun...
270 if (mm_insn_16bit(ip->halfword[1])) {
271 return (ip->mm16_r3_format.opcode == mm_pool16d_op &&
272 ip->mm16_r3_format.simmediate && mm_addiusp_func) ||
273 (ip->mm16_r5_format.opcode == mm_pool16d_op &&
274 ip->mm16_r5_format.rt == 29);
277 return ip->mm_i_format.opcode == mm_addiu32_op &&
278 ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29;
280 /* addiu/daddiu sp,sp,-imm */
281 if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
283 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
289 static int get_frame_info(struct mips_frame_info *info)
291 bool is_mmips = IS_ENABLED(CONFIG_CPU_MICROMIPS);
292 union mips_instruction insn, *ip;
293 unsigned max_insns = info->func_size / sizeof(union mips_instruction);
296 info->pc_offset = -1;
297 info->frame_size = 0;
299 ip = (void *)msk_isa16_mode((ulong)info->func);
304 max_insns = 128U; /* unknown function size */
305 max_insns = min(128U, max_insns);
307 for (i = 0; i < max_insns; i++, ip++) {
308 if (is_mmips && mm_insn_16bit(ip->halfword[0])) {
309 insn.halfword[0] = 0;
310 insn.halfword[1] = ip->halfword[0];
311 } else if (is_mmips) {
312 insn.halfword[0] = ip->halfword[1];
313 insn.halfword[1] = ip->halfword[0];
315 insn.word = ip->word;
318 if (is_jump_ins(&insn))
321 if (!info->frame_size) {
322 if (is_sp_move_ins(&insn))
324 #ifdef CONFIG_CPU_MICROMIPS
325 if (mm_insn_16bit(ip->halfword[0]))
329 if (ip->halfword[0] & mm_addiusp_func)
331 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
332 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
334 tmp = (ip->halfword[0] >> 1);
335 info->frame_size = -(signed short)(tmp & 0xf);
337 ip = (void *) &ip->halfword[1];
341 info->frame_size = - ip->i_format.simmediate;
345 if (info->pc_offset == -1 && is_ra_save_ins(&insn)) {
347 ip->i_format.simmediate / sizeof(long);
351 if (info->frame_size && info->pc_offset >= 0) /* nested */
353 if (info->pc_offset < 0) /* leaf */
355 /* prologue seems boggus... */
360 static struct mips_frame_info schedule_mfi __read_mostly;
362 #ifdef CONFIG_KALLSYMS
363 static unsigned long get___schedule_addr(void)
365 return kallsyms_lookup_name("__schedule");
368 static unsigned long get___schedule_addr(void)
370 union mips_instruction *ip = (void *)schedule;
374 for (i = 0; i < max_insns; i++, ip++) {
375 if (ip->j_format.opcode == j_op)
376 return J_TARGET(ip, ip->j_format.target);
382 static int __init frame_info_init(void)
384 unsigned long size = 0;
385 #ifdef CONFIG_KALLSYMS
390 addr = get___schedule_addr();
392 addr = (unsigned long)schedule;
394 #ifdef CONFIG_KALLSYMS
395 kallsyms_lookup_size_offset(addr, &size, &ofs);
397 schedule_mfi.func = (void *)addr;
398 schedule_mfi.func_size = size;
400 get_frame_info(&schedule_mfi);
403 * Without schedule() frame info, result given by
404 * thread_saved_pc() and get_wchan() are not reliable.
406 if (schedule_mfi.pc_offset < 0)
407 printk("Can't analyze schedule() prologue at %p\n", schedule);
412 arch_initcall(frame_info_init);
415 * Return saved PC of a blocked thread.
417 unsigned long thread_saved_pc(struct task_struct *tsk)
419 struct thread_struct *t = &tsk->thread;
421 /* New born processes are a special case */
422 if (t->reg31 == (unsigned long) ret_from_fork)
424 if (schedule_mfi.pc_offset < 0)
426 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
430 #ifdef CONFIG_KALLSYMS
431 /* generic stack unwinding function */
432 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
437 struct mips_frame_info info;
438 unsigned long size, ofs;
440 extern void ret_from_irq(void);
441 extern void ret_from_exception(void);
447 * If we reached the bottom of interrupt context,
448 * return saved pc in pt_regs.
450 if (pc == (unsigned long)ret_from_irq ||
451 pc == (unsigned long)ret_from_exception) {
452 struct pt_regs *regs;
453 if (*sp >= stack_page &&
454 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
455 regs = (struct pt_regs *)*sp;
457 if (!user_mode(regs) && __kernel_text_address(pc)) {
458 *sp = regs->regs[29];
459 *ra = regs->regs[31];
465 if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
468 * Return ra if an exception occurred at the first instruction
470 if (unlikely(ofs == 0)) {
476 info.func = (void *)(pc - ofs);
477 info.func_size = ofs; /* analyze from start to ofs */
478 leaf = get_frame_info(&info);
482 if (*sp < stack_page ||
483 *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
488 * For some extreme cases, get_frame_info() can
489 * consider wrongly a nested function as a leaf
490 * one. In that cases avoid to return always the
493 pc = pc != *ra ? *ra : 0;
495 pc = ((unsigned long *)(*sp))[info.pc_offset];
497 *sp += info.frame_size;
499 return __kernel_text_address(pc) ? pc : 0;
501 EXPORT_SYMBOL(unwind_stack_by_address);
503 /* used by show_backtrace() */
504 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
505 unsigned long pc, unsigned long *ra)
507 unsigned long stack_page = (unsigned long)task_stack_page(task);
508 return unwind_stack_by_address(stack_page, sp, pc, ra);
513 * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
515 unsigned long get_wchan(struct task_struct *task)
517 unsigned long pc = 0;
518 #ifdef CONFIG_KALLSYMS
520 unsigned long ra = 0;
523 if (!task || task == current || task->state == TASK_RUNNING)
525 if (!task_stack_page(task))
528 pc = thread_saved_pc(task);
530 #ifdef CONFIG_KALLSYMS
531 sp = task->thread.reg29 + schedule_mfi.frame_size;
533 while (in_sched_functions(pc))
534 pc = unwind_stack(task, &sp, pc, &ra);
542 * Don't forget that the stack pointer must be aligned on a 8 bytes
543 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
545 unsigned long arch_align_stack(unsigned long sp)
547 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
548 sp -= get_random_int() & ~PAGE_MASK;
553 static void arch_dump_stack(void *info)
555 struct pt_regs *regs;
557 regs = get_irq_regs();
565 void arch_trigger_all_cpu_backtrace(bool include_self)
567 smp_call_function(arch_dump_stack, NULL, 1);
570 int mips_get_process_fp_mode(struct task_struct *task)
574 if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
575 value |= PR_FP_MODE_FR;
576 if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
577 value |= PR_FP_MODE_FRE;
582 int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
584 const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
585 unsigned long switch_count;
586 struct task_struct *t;
588 /* Check the value is valid */
589 if (value & ~known_bits)
592 /* Avoid inadvertently triggering emulation */
593 if ((value & PR_FP_MODE_FR) && raw_cpu_has_fpu &&
594 !(raw_current_cpu_data.fpu_id & MIPS_FPIR_F64))
596 if ((value & PR_FP_MODE_FRE) && raw_cpu_has_fpu && !cpu_has_fre)
599 /* FR = 0 not supported in MIPS R6 */
600 if (!(value & PR_FP_MODE_FR) && raw_cpu_has_fpu && cpu_has_mips_r6)
603 /* Proceed with the mode switch */
606 /* Save FP & vector context, then disable FPU & MSA */
607 if (task->signal == current->signal)
610 /* Prevent any threads from obtaining live FP context */
611 atomic_set(&task->mm->context.fp_mode_switching, 1);
612 smp_mb__after_atomic();
615 * If there are multiple online CPUs then wait until all threads whose
616 * FP mode is about to change have been context switched. This approach
617 * allows us to only worry about whether an FP mode switch is in
618 * progress when FP is first used in a tasks time slice. Pretty much all
619 * of the mode switch overhead can thus be confined to cases where mode
620 * switches are actually occuring. That is, to here. However for the
621 * thread performing the mode switch it may take a while...
623 if (num_online_cpus() > 1) {
624 spin_lock_irq(&task->sighand->siglock);
626 for_each_thread(task, t) {
630 switch_count = t->nvcsw + t->nivcsw;
633 spin_unlock_irq(&task->sighand->siglock);
635 spin_lock_irq(&task->sighand->siglock);
636 } while ((t->nvcsw + t->nivcsw) == switch_count);
639 spin_unlock_irq(&task->sighand->siglock);
643 * There are now no threads of the process with live FP context, so it
644 * is safe to proceed with the FP mode switch.
646 for_each_thread(task, t) {
647 /* Update desired FP register width */
648 if (value & PR_FP_MODE_FR) {
649 clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
651 set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
652 clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
655 /* Update desired FP single layout */
656 if (value & PR_FP_MODE_FRE)
657 set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
659 clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
662 /* Allow threads to use FP again */
663 atomic_set(&task->mm->context.fp_mode_switching, 0);