1/*
  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
  4 * for more details.
  5 *
  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.
 11 */
 12#include <linux/cpu.h>
 13#include <linux/errno.h>
 14#include <linux/init.h>
 15#include <linux/kallsyms.h>
 
 16#include <linux/kernel.h>
 17#include <linux/nmi.h>
 
 
 
 
 18#include <linux/personality.h>
 19#include <linux/prctl.h>
 
 
 
 
 20#include <linux/random.h>
 21#include <linux/sched.h>
 22#include <linux/sched/debug.h>
 23#include <linux/sched/task_stack.h>
 24
 25#include <asm/abi.h>
 26#include <asm/asm.h>
 27#include <asm/dsemul.h>
 
 28#include <asm/dsp.h>
 29#include <asm/exec.h>
 30#include <asm/fpu.h>
 31#include <asm/inst.h>
 32#include <asm/irq.h>
 33#include <asm/irq_regs.h>
 34#include <asm/isadep.h>
 35#include <asm/msa.h>
 36#include <asm/mips-cps.h>
 37#include <asm/mipsregs.h>
 38#include <asm/processor.h>
 39#include <asm/reg.h>
 
 
 
 
 40#include <asm/stacktrace.h>
 41
 42#ifdef CONFIG_HOTPLUG_CPU
 43void arch_cpu_idle_dead(void)
 
 
 
 
 44{
 45	play_dead();
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 46}
 47#endif
 48
 49asmlinkage void ret_from_fork(void);
 50asmlinkage void ret_from_kernel_thread(void);
 51
 52void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
 53{
 54	unsigned long status;
 55
 56	/* New thread loses kernel privileges. */
 57	status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_CU2|ST0_FR|KU_MASK);
 
 
 
 58	status |= KU_USER;
 59	regs->cp0_status = status;
 60	lose_fpu(0);
 61	clear_thread_flag(TIF_MSA_CTX_LIVE);
 62	clear_used_math();
 63#ifdef CONFIG_MIPS_FP_SUPPORT
 64	atomic_set(&current->thread.bd_emu_frame, BD_EMUFRAME_NONE);
 65#endif
 66	init_dsp();
 67	regs->cp0_epc = pc;
 68	regs->regs[29] = sp;
 69}
 70
 71void exit_thread(struct task_struct *tsk)
 72{
 73	/*
 74	 * User threads may have allocated a delay slot emulation frame.
 75	 * If so, clean up that allocation.
 76	 */
 77	if (!(current->flags & PF_KTHREAD))
 78		dsemul_thread_cleanup(tsk);
 79}
 80
 81int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 82{
 83	/*
 84	 * Save any process state which is live in hardware registers to the
 85	 * parent context prior to duplication. This prevents the new child
 86	 * state becoming stale if the parent is preempted before copy_thread()
 87	 * gets a chance to save the parent's live hardware registers to the
 88	 * child context.
 89	 */
 90	preempt_disable();
 91
 92	if (is_msa_enabled())
 93		save_msa(current);
 94	else if (is_fpu_owner())
 95		_save_fp(current);
 96
 97	save_dsp(current);
 98
 99	preempt_enable();
100
101	*dst = *src;
102	return 0;
103}
104
105/*
106 * Copy architecture-specific thread state
107 */
108int copy_thread(unsigned long clone_flags, unsigned long usp,
109		unsigned long kthread_arg, struct task_struct *p,
110		unsigned long tls)
111{
112	struct thread_info *ti = task_thread_info(p);
113	struct pt_regs *childregs, *regs = current_pt_regs();
114	unsigned long childksp;
 
115
116	childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
117
 
 
 
 
 
 
 
 
 
 
118	/* set up new TSS. */
119	childregs = (struct pt_regs *) childksp - 1;
120	/*  Put the stack after the struct pt_regs.  */
121	childksp = (unsigned long) childregs;
122	p->thread.cp0_status = (read_c0_status() & ~(ST0_CU2|ST0_CU1)) | ST0_KERNEL_CUMASK;
123	if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
124		/* kernel thread */
125		unsigned long status = p->thread.cp0_status;
126		memset(childregs, 0, sizeof(struct pt_regs));
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);
134#else
135		status |= ST0_EXL;
136#endif
137		childregs->cp0_status = status;
138		return 0;
139	}
140
141	/* user thread */
142	*childregs = *regs;
143	childregs->regs[7] = 0; /* Clear error flag */
144	childregs->regs[2] = 0; /* Child gets zero as return value */
145	if (usp)
146		childregs->regs[29] = usp;
147
 
 
 
 
 
 
 
 
 
 
148	p->thread.reg29 = (unsigned long) childregs;
149	p->thread.reg31 = (unsigned long) ret_from_fork;
150
151	/*
152	 * New tasks lose permission to use the fpu. This accelerates context
153	 * switching for most programs since they don't use the fpu.
154	 */
 
155	childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
156
 
 
 
 
 
 
 
157	clear_tsk_thread_flag(p, TIF_USEDFPU);
158	clear_tsk_thread_flag(p, TIF_USEDMSA);
159	clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
160
161#ifdef CONFIG_MIPS_MT_FPAFF
162	clear_tsk_thread_flag(p, TIF_FPUBOUND);
163#endif /* CONFIG_MIPS_MT_FPAFF */
164
165#ifdef CONFIG_MIPS_FP_SUPPORT
166	atomic_set(&p->thread.bd_emu_frame, BD_EMUFRAME_NONE);
167#endif
168
169	if (clone_flags & CLONE_SETTLS)
170		ti->tp_value = tls;
171
172	return 0;
173}
174
175#ifdef CONFIG_STACKPROTECTOR
176#include <linux/stackprotector.h>
177unsigned long __stack_chk_guard __read_mostly;
178EXPORT_SYMBOL(__stack_chk_guard);
179#endif
180
181struct mips_frame_info {
182	void		*func;
183	unsigned long	func_size;
184	int		frame_size;
185	int		pc_offset;
186};
187
188#define J_TARGET(pc,target)	\
189		(((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
190
191static inline int is_jr_ra_ins(union mips_instruction *ip)
192{
193#ifdef CONFIG_CPU_MICROMIPS
194	/*
195	 * jr16 ra
196	 * jr ra
197	 */
198	if (mm_insn_16bit(ip->word >> 16)) {
199		if (ip->mm16_r5_format.opcode == mm_pool16c_op &&
200		    ip->mm16_r5_format.rt == mm_jr16_op &&
201		    ip->mm16_r5_format.imm == 31)
202			return 1;
203		return 0;
204	}
205
206	if (ip->r_format.opcode == mm_pool32a_op &&
207	    ip->r_format.func == mm_pool32axf_op &&
208	    ((ip->u_format.uimmediate >> 6) & GENMASK(9, 0)) == mm_jalr_op &&
209	    ip->r_format.rt == 31)
210		return 1;
211	return 0;
212#else
213	if (ip->r_format.opcode == spec_op &&
214	    ip->r_format.func == jr_op &&
215	    ip->r_format.rs == 31)
216		return 1;
217	return 0;
 
 
 
218#endif
219}
220
221static inline int is_ra_save_ins(union mips_instruction *ip, int *poff)
222{
223#ifdef CONFIG_CPU_MICROMIPS
224	/*
225	 * swsp ra,offset
226	 * swm16 reglist,offset(sp)
227	 * swm32 reglist,offset(sp)
228	 * sw32 ra,offset(sp)
229	 * jradiussp - NOT SUPPORTED
230	 *
231	 * microMIPS is way more fun...
232	 */
233	if (mm_insn_16bit(ip->word >> 16)) {
234		switch (ip->mm16_r5_format.opcode) {
235		case mm_swsp16_op:
236			if (ip->mm16_r5_format.rt != 31)
237				return 0;
238
239			*poff = ip->mm16_r5_format.imm;
240			*poff = (*poff << 2) / sizeof(ulong);
241			return 1;
242
243		case mm_pool16c_op:
244			switch (ip->mm16_m_format.func) {
245			case mm_swm16_op:
246				*poff = ip->mm16_m_format.imm;
247				*poff += 1 + ip->mm16_m_format.rlist;
248				*poff = (*poff << 2) / sizeof(ulong);
249				return 1;
250
251			default:
252				return 0;
253			}
254
255		default:
256			return 0;
257		}
258	}
259
260	switch (ip->i_format.opcode) {
261	case mm_sw32_op:
262		if (ip->i_format.rs != 29)
263			return 0;
264		if (ip->i_format.rt != 31)
265			return 0;
 
266
267		*poff = ip->i_format.simmediate / sizeof(ulong);
268		return 1;
 
269
270	case mm_pool32b_op:
271		switch (ip->mm_m_format.func) {
272		case mm_swm32_func:
273			if (ip->mm_m_format.rd < 0x10)
274				return 0;
275			if (ip->mm_m_format.base != 29)
276				return 0;
277
278			*poff = ip->mm_m_format.simmediate;
279			*poff += (ip->mm_m_format.rd & 0xf) * sizeof(u32);
280			*poff /= sizeof(ulong);
281			return 1;
282		default:
283			return 0;
284		}
285
286	default:
287		return 0;
288	}
 
 
 
 
289#else
290	/* sw / sd $ra, offset($sp) */
291	if ((ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
292		ip->i_format.rs == 29 && ip->i_format.rt == 31) {
293		*poff = ip->i_format.simmediate / sizeof(ulong);
294		return 1;
295	}
296#ifdef CONFIG_CPU_LOONGSON64
297	if ((ip->loongson3_lswc2_format.opcode == swc2_op) &&
298		      (ip->loongson3_lswc2_format.ls == 1) &&
299		      (ip->loongson3_lswc2_format.fr == 0) &&
300		      (ip->loongson3_lswc2_format.base == 29)) {
301		if (ip->loongson3_lswc2_format.rt == 31) {
302			*poff = ip->loongson3_lswc2_format.offset << 1;
303			return 1;
304		}
305		if (ip->loongson3_lswc2_format.rq == 31) {
306			*poff = (ip->loongson3_lswc2_format.offset << 1) + 1;
307			return 1;
308		}
309	}
310#endif
311	return 0;
312#endif
 
 
 
313}
314
315static inline int is_jump_ins(union mips_instruction *ip)
 
 
 
 
 
 
 
 
 
 
316{
317#ifdef CONFIG_CPU_MICROMIPS
318	/*
319	 * jr16,jrc,jalr16,jalr16
320	 * jal
321	 * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
322	 * jraddiusp - NOT SUPPORTED
323	 *
324	 * microMIPS is kind of more fun...
325	 */
326	if (mm_insn_16bit(ip->word >> 16)) {
327		if ((ip->mm16_r5_format.opcode == mm_pool16c_op &&
328		    (ip->mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op))
329			return 1;
330		return 0;
331	}
332
333	if (ip->j_format.opcode == mm_j32_op)
334		return 1;
335	if (ip->j_format.opcode == mm_jal32_op)
336		return 1;
337	if (ip->r_format.opcode != mm_pool32a_op ||
338			ip->r_format.func != mm_pool32axf_op)
339		return 0;
340	return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
341#else
342	if (ip->j_format.opcode == j_op)
343		return 1;
344	if (ip->j_format.opcode == jal_op)
345		return 1;
346	if (ip->r_format.opcode != spec_op)
347		return 0;
348	return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
349#endif
350}
351
352static inline int is_sp_move_ins(union mips_instruction *ip, int *frame_size)
353{
354#ifdef CONFIG_CPU_MICROMIPS
355	unsigned short tmp;
356
357	/*
358	 * addiusp -imm
359	 * addius5 sp,-imm
360	 * addiu32 sp,sp,-imm
361	 * jradiussp - NOT SUPPORTED
362	 *
363	 * microMIPS is not more fun...
364	 */
365	if (mm_insn_16bit(ip->word >> 16)) {
366		if (ip->mm16_r3_format.opcode == mm_pool16d_op &&
367		    ip->mm16_r3_format.simmediate & mm_addiusp_func) {
368			tmp = ip->mm_b0_format.simmediate >> 1;
369			tmp = ((tmp & 0x1ff) ^ 0x100) - 0x100;
370			if ((tmp + 2) < 4) /* 0x0,0x1,0x1fe,0x1ff are special */
371				tmp ^= 0x100;
372			*frame_size = -(signed short)(tmp << 2);
373			return 1;
374		}
375		if (ip->mm16_r5_format.opcode == mm_pool16d_op &&
376		    ip->mm16_r5_format.rt == 29) {
377			tmp = ip->mm16_r5_format.imm >> 1;
378			*frame_size = -(signed short)(tmp & 0xf);
379			return 1;
380		}
381		return 0;
382	}
383
384	if (ip->mm_i_format.opcode == mm_addiu32_op &&
385	    ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29) {
386		*frame_size = -ip->i_format.simmediate;
387		return 1;
388	}
389#else
390	/* addiu/daddiu sp,sp,-imm */
391	if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
392		return 0;
393
394	if (ip->i_format.opcode == addiu_op ||
395	    ip->i_format.opcode == daddiu_op) {
396		*frame_size = -ip->i_format.simmediate;
397		return 1;
398	}
399#endif
400	return 0;
401}
402
403static int get_frame_info(struct mips_frame_info *info)
404{
405	bool is_mmips = IS_ENABLED(CONFIG_CPU_MICROMIPS);
406	union mips_instruction insn, *ip, *ip_end;
407	unsigned int last_insn_size = 0;
408	bool saw_jump = false;
409
410	info->pc_offset = -1;
411	info->frame_size = 0;
412
413	ip = (void *)msk_isa16_mode((ulong)info->func);
414	if (!ip)
415		goto err;
416
417	ip_end = (void *)ip + (info->func_size ? info->func_size : 512);
 
 
418
419	while (ip < ip_end) {
420		ip = (void *)ip + last_insn_size;
421
422		if (is_mmips && mm_insn_16bit(ip->halfword[0])) {
423			insn.word = ip->halfword[0] << 16;
424			last_insn_size = 2;
425		} else if (is_mmips) {
426			insn.word = ip->halfword[0] << 16 | ip->halfword[1];
427			last_insn_size = 4;
428		} else {
429			insn.word = ip->word;
430			last_insn_size = 4;
431		}
432
433		if (is_jr_ra_ins(ip)) {
434			break;
435		} else if (!info->frame_size) {
436			is_sp_move_ins(&insn, &info->frame_size);
437			continue;
438		} else if (!saw_jump && is_jump_ins(ip)) {
439			/*
440			 * If we see a jump instruction, we are finished
441			 * with the frame save.
442			 *
443			 * Some functions can have a shortcut return at
444			 * the beginning of the function, so don't start
445			 * looking for jump instruction until we see the
446			 * frame setup.
447			 *
448			 * The RA save instruction can get put into the
449			 * delay slot of the jump instruction, so look
450			 * at the next instruction, too.
451			 */
452			saw_jump = true;
453			continue;
454		}
455		if (info->pc_offset == -1 &&
456		    is_ra_save_ins(&insn, &info->pc_offset))
457			break;
458		if (saw_jump)
459			break;
 
460	}
461	if (info->frame_size && info->pc_offset >= 0) /* nested */
462		return 0;
463	if (info->pc_offset < 0) /* leaf */
464		return 1;
465	/* prologue seems bogus... */
466err:
467	return -1;
468}
469
470static struct mips_frame_info schedule_mfi __read_mostly;
471
472#ifdef CONFIG_KALLSYMS
473static unsigned long get___schedule_addr(void)
474{
475	return kallsyms_lookup_name("__schedule");
476}
477#else
478static unsigned long get___schedule_addr(void)
479{
480	union mips_instruction *ip = (void *)schedule;
481	int max_insns = 8;
482	int i;
483
484	for (i = 0; i < max_insns; i++, ip++) {
485		if (ip->j_format.opcode == j_op)
486			return J_TARGET(ip, ip->j_format.target);
487	}
488	return 0;
489}
490#endif
491
492static int __init frame_info_init(void)
493{
494	unsigned long size = 0;
495#ifdef CONFIG_KALLSYMS
496	unsigned long ofs;
497#endif
498	unsigned long addr;
499
500	addr = get___schedule_addr();
501	if (!addr)
502		addr = (unsigned long)schedule;
503
504#ifdef CONFIG_KALLSYMS
505	kallsyms_lookup_size_offset(addr, &size, &ofs);
506#endif
507	schedule_mfi.func = (void *)addr;
508	schedule_mfi.func_size = size;
509
510	get_frame_info(&schedule_mfi);
511
512	/*
513	 * Without schedule() frame info, result given by
514	 * thread_saved_pc() and get_wchan() are not reliable.
515	 */
516	if (schedule_mfi.pc_offset < 0)
517		printk("Can't analyze schedule() prologue at %p\n", schedule);
518
519	return 0;
520}
521
522arch_initcall(frame_info_init);
523
524/*
525 * Return saved PC of a blocked thread.
526 */
527static unsigned long thread_saved_pc(struct task_struct *tsk)
528{
529	struct thread_struct *t = &tsk->thread;
530
531	/* New born processes are a special case */
532	if (t->reg31 == (unsigned long) ret_from_fork)
533		return t->reg31;
534	if (schedule_mfi.pc_offset < 0)
535		return 0;
536	return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
537}
538
539
540#ifdef CONFIG_KALLSYMS
541/* generic stack unwinding function */
542unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
543					      unsigned long *sp,
544					      unsigned long pc,
545					      unsigned long *ra)
546{
547	unsigned long low, high, irq_stack_high;
548	struct mips_frame_info info;
549	unsigned long size, ofs;
550	struct pt_regs *regs;
551	int leaf;
 
 
552
553	if (!stack_page)
554		return 0;
555
556	/*
557	 * IRQ stacks start at IRQ_STACK_START
558	 * task stacks at THREAD_SIZE - 32
559	 */
560	low = stack_page;
561	if (!preemptible() && on_irq_stack(raw_smp_processor_id(), *sp)) {
562		high = stack_page + IRQ_STACK_START;
563		irq_stack_high = high;
564	} else {
565		high = stack_page + THREAD_SIZE - 32;
566		irq_stack_high = 0;
567	}
568
569	/*
570	 * If we reached the top of the interrupt stack, start unwinding
571	 * the interrupted task stack.
572	 */
573	if (unlikely(*sp == irq_stack_high)) {
574		unsigned long task_sp = *(unsigned long *)*sp;
575
576		/*
577		 * Check that the pointer saved in the IRQ stack head points to
578		 * something within the stack of the current task
579		 */
580		if (!object_is_on_stack((void *)task_sp))
581			return 0;
582
583		/*
584		 * Follow pointer to tasks kernel stack frame where interrupted
585		 * state was saved.
586		 */
587		regs = (struct pt_regs *)task_sp;
588		pc = regs->cp0_epc;
589		if (!user_mode(regs) && __kernel_text_address(pc)) {
590			*sp = regs->regs[29];
591			*ra = regs->regs[31];
592			return pc;
593		}
594		return 0;
595	}
596	if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
597		return 0;
598	/*
599	 * Return ra if an exception occurred at the first instruction
600	 */
601	if (unlikely(ofs == 0)) {
602		pc = *ra;
603		*ra = 0;
604		return pc;
605	}
606
607	info.func = (void *)(pc - ofs);
608	info.func_size = ofs;	/* analyze from start to ofs */
609	leaf = get_frame_info(&info);
610	if (leaf < 0)
611		return 0;
612
613	if (*sp < low || *sp + info.frame_size > high)
 
614		return 0;
615
616	if (leaf)
617		/*
618		 * For some extreme cases, get_frame_info() can
619		 * consider wrongly a nested function as a leaf
620		 * one. In that cases avoid to return always the
621		 * same value.
622		 */
623		pc = pc != *ra ? *ra : 0;
624	else
625		pc = ((unsigned long *)(*sp))[info.pc_offset];
626
627	*sp += info.frame_size;
628	*ra = 0;
629	return __kernel_text_address(pc) ? pc : 0;
630}
631EXPORT_SYMBOL(unwind_stack_by_address);
632
633/* used by show_backtrace() */
634unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
635			   unsigned long pc, unsigned long *ra)
636{
637	unsigned long stack_page = 0;
638	int cpu;
639
640	for_each_possible_cpu(cpu) {
641		if (on_irq_stack(cpu, *sp)) {
642			stack_page = (unsigned long)irq_stack[cpu];
643			break;
644		}
645	}
646
647	if (!stack_page)
648		stack_page = (unsigned long)task_stack_page(task);
649
650	return unwind_stack_by_address(stack_page, sp, pc, ra);
651}
652#endif
653
654/*
655 * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
656 */
657unsigned long get_wchan(struct task_struct *task)
658{
659	unsigned long pc = 0;
660#ifdef CONFIG_KALLSYMS
661	unsigned long sp;
662	unsigned long ra = 0;
663#endif
664
665	if (!task || task == current || task_is_running(task))
666		goto out;
667	if (!task_stack_page(task))
668		goto out;
669
670	pc = thread_saved_pc(task);
671
672#ifdef CONFIG_KALLSYMS
673	sp = task->thread.reg29 + schedule_mfi.frame_size;
674
675	while (in_sched_functions(pc))
676		pc = unwind_stack(task, &sp, pc, &ra);
677#endif
678
679out:
680	return pc;
681}
682
683unsigned long mips_stack_top(void)
684{
685	unsigned long top = TASK_SIZE & PAGE_MASK;
686
687	if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) {
688		/* One page for branch delay slot "emulation" */
689		top -= PAGE_SIZE;
690	}
691
692	/* Space for the VDSO, data page & GIC user page */
693	top -= PAGE_ALIGN(current->thread.abi->vdso->size);
694	top -= PAGE_SIZE;
695	top -= mips_gic_present() ? PAGE_SIZE : 0;
696
697	/* Space for cache colour alignment */
698	if (cpu_has_dc_aliases)
699		top -= shm_align_mask + 1;
700
701	/* Space to randomize the VDSO base */
702	if (current->flags & PF_RANDOMIZE)
703		top -= VDSO_RANDOMIZE_SIZE;
704
705	return top;
706}
707
708/*
709 * Don't forget that the stack pointer must be aligned on a 8 bytes
710 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
711 */
712unsigned long arch_align_stack(unsigned long sp)
713{
714	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
715		sp -= get_random_int() & ~PAGE_MASK;
716
717	return sp & ALMASK;
718}
719
720static struct cpumask backtrace_csd_busy;
721
722static void handle_backtrace(void *info)
723{
724	nmi_cpu_backtrace(get_irq_regs());
725	cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
726}
727
728static DEFINE_PER_CPU(call_single_data_t, backtrace_csd) =
729	CSD_INIT(handle_backtrace, NULL);
730
731static void raise_backtrace(cpumask_t *mask)
732{
733	call_single_data_t *csd;
734	int cpu;
735
736	for_each_cpu(cpu, mask) {
737		/*
738		 * If we previously sent an IPI to the target CPU & it hasn't
739		 * cleared its bit in the busy cpumask then it didn't handle
740		 * our previous IPI & it's not safe for us to reuse the
741		 * call_single_data_t.
742		 */
743		if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) {
744			pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
745				cpu);
746			continue;
747		}
748
749		csd = &per_cpu(backtrace_csd, cpu);
750		smp_call_function_single_async(cpu, csd);
751	}
752}
753
754void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
755{
756	nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace);
757}
758
759int mips_get_process_fp_mode(struct task_struct *task)
760{
761	int value = 0;
762
763	if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
764		value |= PR_FP_MODE_FR;
765	if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
766		value |= PR_FP_MODE_FRE;
767
768	return value;
769}
770
771static long prepare_for_fp_mode_switch(void *unused)
772{
773	/*
774	 * This is icky, but we use this to simply ensure that all CPUs have
775	 * context switched, regardless of whether they were previously running
776	 * kernel or user code. This ensures that no CPU that a mode-switching
777	 * program may execute on keeps its FPU enabled (& in the old mode)
778	 * throughout the mode switch.
779	 */
780	return 0;
781}
782
783int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
784{
785	const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
786	struct task_struct *t;
787	struct cpumask process_cpus;
788	int cpu;
789
790	/* If nothing to change, return right away, successfully.  */
791	if (value == mips_get_process_fp_mode(task))
792		return 0;
793
794	/* Only accept a mode change if 64-bit FP enabled for o32.  */
795	if (!IS_ENABLED(CONFIG_MIPS_O32_FP64_SUPPORT))
796		return -EOPNOTSUPP;
797
798	/* And only for o32 tasks.  */
799	if (IS_ENABLED(CONFIG_64BIT) && !test_thread_flag(TIF_32BIT_REGS))
800		return -EOPNOTSUPP;
801
802	/* Check the value is valid */
803	if (value & ~known_bits)
804		return -EOPNOTSUPP;
805
806	/* Setting FRE without FR is not supported.  */
807	if ((value & (PR_FP_MODE_FR | PR_FP_MODE_FRE)) == PR_FP_MODE_FRE)
808		return -EOPNOTSUPP;
809
810	/* Avoid inadvertently triggering emulation */
811	if ((value & PR_FP_MODE_FR) && raw_cpu_has_fpu &&
812	    !(raw_current_cpu_data.fpu_id & MIPS_FPIR_F64))
813		return -EOPNOTSUPP;
814	if ((value & PR_FP_MODE_FRE) && raw_cpu_has_fpu && !cpu_has_fre)
815		return -EOPNOTSUPP;
816
817	/* FR = 0 not supported in MIPS R6 */
818	if (!(value & PR_FP_MODE_FR) && raw_cpu_has_fpu && cpu_has_mips_r6)
819		return -EOPNOTSUPP;
820
821	/* Indicate the new FP mode in each thread */
822	for_each_thread(task, t) {
823		/* Update desired FP register width */
824		if (value & PR_FP_MODE_FR) {
825			clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
826		} else {
827			set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
828			clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
829		}
830
831		/* Update desired FP single layout */
832		if (value & PR_FP_MODE_FRE)
833			set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
834		else
835			clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
836	}
837
838	/*
839	 * We need to ensure that all threads in the process have switched mode
840	 * before returning, in order to allow userland to not worry about
841	 * races. We can do this by forcing all CPUs that any thread in the
842	 * process may be running on to schedule something else - in this case
843	 * prepare_for_fp_mode_switch().
844	 *
845	 * We begin by generating a mask of all CPUs that any thread in the
846	 * process may be running on.
847	 */
848	cpumask_clear(&process_cpus);
849	for_each_thread(task, t)
850		cpumask_set_cpu(task_cpu(t), &process_cpus);
851
852	/*
853	 * Now we schedule prepare_for_fp_mode_switch() on each of those CPUs.
854	 *
855	 * The CPUs may have rescheduled already since we switched mode or
856	 * generated the cpumask, but that doesn't matter. If the task in this
857	 * process is scheduled out then our scheduling
858	 * prepare_for_fp_mode_switch() will simply be redundant. If it's
859	 * scheduled in then it will already have picked up the new FP mode
860	 * whilst doing so.
861	 */
862	get_online_cpus();
863	for_each_cpu_and(cpu, &process_cpus, cpu_online_mask)
864		work_on_cpu(cpu, prepare_for_fp_mode_switch, NULL);
865	put_online_cpus();
866
867	return 0;
868}
869
870#if defined(CONFIG_32BIT) || defined(CONFIG_MIPS32_O32)
871void mips_dump_regs32(u32 *uregs, const struct pt_regs *regs)
872{
873	unsigned int i;
874
875	for (i = MIPS32_EF_R1; i <= MIPS32_EF_R31; i++) {
876		/* k0/k1 are copied as zero. */
877		if (i == MIPS32_EF_R26 || i == MIPS32_EF_R27)
878			uregs[i] = 0;
879		else
880			uregs[i] = regs->regs[i - MIPS32_EF_R0];
881	}
882
883	uregs[MIPS32_EF_LO] = regs->lo;
884	uregs[MIPS32_EF_HI] = regs->hi;
885	uregs[MIPS32_EF_CP0_EPC] = regs->cp0_epc;
886	uregs[MIPS32_EF_CP0_BADVADDR] = regs->cp0_badvaddr;
887	uregs[MIPS32_EF_CP0_STATUS] = regs->cp0_status;
888	uregs[MIPS32_EF_CP0_CAUSE] = regs->cp0_cause;
889}
890#endif /* CONFIG_32BIT || CONFIG_MIPS32_O32 */
891
892#ifdef CONFIG_64BIT
893void mips_dump_regs64(u64 *uregs, const struct pt_regs *regs)
894{
895	unsigned int i;
896
897	for (i = MIPS64_EF_R1; i <= MIPS64_EF_R31; i++) {
898		/* k0/k1 are copied as zero. */
899		if (i == MIPS64_EF_R26 || i == MIPS64_EF_R27)
900			uregs[i] = 0;
901		else
902			uregs[i] = regs->regs[i - MIPS64_EF_R0];
903	}
904
905	uregs[MIPS64_EF_LO] = regs->lo;
906	uregs[MIPS64_EF_HI] = regs->hi;
907	uregs[MIPS64_EF_CP0_EPC] = regs->cp0_epc;
908	uregs[MIPS64_EF_CP0_BADVADDR] = regs->cp0_badvaddr;
909	uregs[MIPS64_EF_CP0_STATUS] = regs->cp0_status;
910	uregs[MIPS64_EF_CP0_CAUSE] = regs->cp0_cause;
911}
912#endif /* CONFIG_64BIT */