1 files changed, 553 insertions, 219 deletions

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index ddc76103e78c..a3101f2268c6 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -9,45 +9,40 @@
  * Copyright (C) 2004 Thiemo Seufer
  * Copyright (C) 2013  Imagination Technologies Ltd.
  */
+#include <linux/cpu.h>
 #include <linux/errno.h>
-#include <linux/sched.h>
-#include <linux/tick.h>
-#include <linux/kernel.h>
-#include <linux/mm.h>
-#include <linux/stddef.h>
-#include <linux/unistd.h>
-#include <linux/export.h>
-#include <linux/ptrace.h>
-#include <linux/mman.h>
-#include <linux/personality.h>
-#include <linux/sys.h>
-#include <linux/user.h>
 #include <linux/init.h>
-#include <linux/completion.h>
 #include <linux/kallsyms.h>
+#include <linux/kernel.h>
+#include <linux/nmi.h>
+#include <linux/personality.h>
+#include <linux/prctl.h>
 #include <linux/random.h>
+#include <linux/sched.h>
+#include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
 
+#include <asm/abi.h>
 #include <asm/asm.h>
-#include <asm/bootinfo.h>
-#include <asm/cpu.h>
+#include <asm/dsemul.h>
 #include <asm/dsp.h>
+#include <asm/exec.h>
 #include <asm/fpu.h>
-#include <asm/pgtable.h>
+#include <asm/inst.h>
+#include <asm/irq.h>
+#include <asm/irq_regs.h>
+#include <asm/isadep.h>
+#include <asm/msa.h>
+#include <asm/mips-cps.h>
 #include <asm/mipsregs.h>
 #include <asm/processor.h>
-#include <asm/uaccess.h>
-#include <asm/io.h>
-#include <asm/elf.h>
-#include <asm/isadep.h>
-#include <asm/inst.h>
+#include <asm/reg.h>
 #include <asm/stacktrace.h>
 
 #ifdef CONFIG_HOTPLUG_CPU
-void arch_cpu_idle_dead(void)
+void __noreturn arch_cpu_idle_dead(void)
 {
-	/* What the heck is this check doing ? */
-	if (!cpu_isset(smp_processor_id(), cpu_callin_map))
-		play_dead();
+	play_dead();
 }
 #endif
 
@@ -59,62 +54,95 @@ void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
 	unsigned long status;
 
 	/* New thread loses kernel privileges. */
-	status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
-#ifdef CONFIG_64BIT
-	status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR;
-#endif
+	status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_CU2|ST0_FR|KU_MASK);
 	status |= KU_USER;
 	regs->cp0_status = status;
+	lose_fpu(0);
+	clear_thread_flag(TIF_MSA_CTX_LIVE);
 	clear_used_math();
-	clear_fpu_owner();
-	if (cpu_has_dsp)
-		__init_dsp();
+#ifdef CONFIG_MIPS_FP_SUPPORT
+	atomic_set(&current->thread.bd_emu_frame, BD_EMUFRAME_NONE);
+#endif
+	init_dsp();
 	regs->cp0_epc = pc;
 	regs->regs[29] = sp;
 }
 
-void exit_thread(void)
+void exit_thread(struct task_struct *tsk)
 {
+	/*
+	 * User threads may have allocated a delay slot emulation frame.
+	 * If so, clean up that allocation.
+	 */
+	if (!(current->flags & PF_KTHREAD))
+		dsemul_thread_cleanup(tsk);
 }
 
-void flush_thread(void)
+int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
+	/*
+	 * Save any process state which is live in hardware registers to the
+	 * parent context prior to duplication. This prevents the new child
+	 * state becoming stale if the parent is preempted before copy_thread()
+	 * gets a chance to save the parent's live hardware registers to the
+	 * child context.
+	 */
+	preempt_disable();
+
+	if (is_msa_enabled())
+		save_msa(current);
+	else if (is_fpu_owner())
+		_save_fp(current);
+
+	save_dsp(current);
+
+	preempt_enable();
+
+	*dst = *src;
+	return 0;
 }
 
-int copy_thread(unsigned long clone_flags, unsigned long usp,
-	unsigned long arg, struct task_struct *p)
+/*
+ * Copy architecture-specific thread state
+ */
+int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 {
+	u64 clone_flags = args->flags;
+	unsigned long usp = args->stack;
+	unsigned long tls = args->tls;
 	struct thread_info *ti = task_thread_info(p);
 	struct pt_regs *childregs, *regs = current_pt_regs();
 	unsigned long childksp;
-	p->set_child_tid = p->clear_child_tid = NULL;
 
 	childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
 
-	preempt_disable();
-
-	if (is_fpu_owner())
-		save_fp(p);
-
-	if (cpu_has_dsp)
-		save_dsp(p);
-
-	preempt_enable();
-
 	/* set up new TSS. */
 	childregs = (struct pt_regs *) childksp - 1;
 	/*  Put the stack after the struct pt_regs.  */
 	childksp = (unsigned long) childregs;
-	p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
-	if (unlikely(p->flags & PF_KTHREAD)) {
+	p->thread.cp0_status = (read_c0_status() & ~(ST0_CU2|ST0_CU1)) | ST0_KERNEL_CUMASK;
+
+	/*
+	 * New tasks lose permission to use the fpu. This accelerates context
+	 * switching for most programs since they don't use the fpu.
+	 */
+	clear_tsk_thread_flag(p, TIF_USEDFPU);
+	clear_tsk_thread_flag(p, TIF_USEDMSA);
+	clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
+
+#ifdef CONFIG_MIPS_MT_FPAFF
+	clear_tsk_thread_flag(p, TIF_FPUBOUND);
+#endif /* CONFIG_MIPS_MT_FPAFF */
+
+	if (unlikely(args->fn)) {
+		/* kernel thread */
 		unsigned long status = p->thread.cp0_status;
 		memset(childregs, 0, sizeof(struct pt_regs));
-		ti->addr_limit = KERNEL_DS;
-		p->thread.reg16 = usp; /* fn */
-		p->thread.reg17 = arg;
+		p->thread.reg16 = (unsigned long)args->fn;
+		p->thread.reg17 = (unsigned long)args->fn_arg;
 		p->thread.reg29 = childksp;
 		p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
-#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
+#if defined(CONFIG_CPU_R3000)
 		status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
 			 ((status & (ST0_KUC | ST0_IEC)) << 2);
 #else
@@ -123,85 +151,30 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
 		childregs->cp0_status = status;
 		return 0;
 	}
+
+	/* user thread */
 	*childregs = *regs;
 	childregs->regs[7] = 0; /* Clear error flag */
 	childregs->regs[2] = 0; /* Child gets zero as return value */
 	if (usp)
 		childregs->regs[29] = usp;
-	ti->addr_limit = USER_DS;
 
 	p->thread.reg29 = (unsigned long) childregs;
 	p->thread.reg31 = (unsigned long) ret_from_fork;
 
-	/*
-	 * New tasks lose permission to use the fpu. This accelerates context
-	 * switching for most programs since they don't use the fpu.
-	 */
 	childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 
-#ifdef CONFIG_MIPS_MT_SMTC
-	/*
-	 * SMTC restores TCStatus after Status, and the CU bits
-	 * are aliased there.
-	 */
-	childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1);
+#ifdef CONFIG_MIPS_FP_SUPPORT
+	atomic_set(&p->thread.bd_emu_frame, BD_EMUFRAME_NONE);
 #endif
-	clear_tsk_thread_flag(p, TIF_USEDFPU);
-
-#ifdef CONFIG_MIPS_MT_FPAFF
-	clear_tsk_thread_flag(p, TIF_FPUBOUND);
-#endif /* CONFIG_MIPS_MT_FPAFF */
 
 	if (clone_flags & CLONE_SETTLS)
-		ti->tp_value = regs->regs[7];
+		ti->tp_value = tls;
 
 	return 0;
 }
 
-/* Fill in the fpu structure for a core dump.. */
-int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
-{
-	memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
-
-	return 1;
-}
-
-void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs)
-{
-	int i;
-
-	for (i = 0; i < EF_R0; i++)
-		gp[i] = 0;
-	gp[EF_R0] = 0;
-	for (i = 1; i <= 31; i++)
-		gp[EF_R0 + i] = regs->regs[i];
-	gp[EF_R26] = 0;
-	gp[EF_R27] = 0;
-	gp[EF_LO] = regs->lo;
-	gp[EF_HI] = regs->hi;
-	gp[EF_CP0_EPC] = regs->cp0_epc;
-	gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
-	gp[EF_CP0_STATUS] = regs->cp0_status;
-	gp[EF_CP0_CAUSE] = regs->cp0_cause;
-#ifdef EF_UNUSED0
-	gp[EF_UNUSED0] = 0;
-#endif
-}
-
-int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
-{
-	elf_dump_regs(*regs, task_pt_regs(tsk));
-	return 1;
-}
-
-int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr)
-{
-	memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
-
-	return 1;
-}
-
-#ifdef CONFIG_CC_STACKPROTECTOR
+#ifdef CONFIG_STACKPROTECTOR
 #include <linux/stackprotector.h>
 unsigned long __stack_chk_guard __read_mostly;
 EXPORT_SYMBOL(__stack_chk_guard);
@@ -217,11 +190,39 @@ struct mips_frame_info {
 #define J_TARGET(pc,target)	\
 		(((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
 
-static inline int is_ra_save_ins(union mips_instruction *ip)
+static inline int is_jr_ra_ins(union mips_instruction *ip)
 {
 #ifdef CONFIG_CPU_MICROMIPS
-	union mips_instruction mmi;
+	/*
+	 * jr16 ra
+	 * jr ra
+	 */
+	if (mm_insn_16bit(ip->word >> 16)) {
+		if (ip->mm16_r5_format.opcode == mm_pool16c_op &&
+		    ip->mm16_r5_format.rt == mm_jr16_op &&
+		    ip->mm16_r5_format.imm == 31)
+			return 1;
+		return 0;
+	}
+
+	if (ip->r_format.opcode == mm_pool32a_op &&
+	    ip->r_format.func == mm_pool32axf_op &&
+	    ((ip->u_format.uimmediate >> 6) & GENMASK(9, 0)) == mm_jalr_op &&
+	    ip->r_format.rt == 31)
+		return 1;
+	return 0;
+#else
+	if (ip->r_format.opcode == spec_op &&
+	    ip->r_format.func == jr_op &&
+	    ip->r_format.rs == 31)
+		return 1;
+	return 0;
+#endif
+}
 
+static inline int is_ra_save_ins(union mips_instruction *ip, int *poff)
+{
+#ifdef CONFIG_CPU_MICROMIPS
 	/*
 	 * swsp ra,offset
 	 * swm16 reglist,offset(sp)
@@ -231,29 +232,85 @@ static inline int is_ra_save_ins(union mips_instruction *ip)
 	 *
 	 * microMIPS is way more fun...
 	 */
-	if (mm_insn_16bit(ip->halfword[0])) {
-		mmi.word = (ip->halfword[0] << 16);
-		return ((mmi.mm16_r5_format.opcode == mm_swsp16_op &&
-			 mmi.mm16_r5_format.rt == 31) ||
-			(mmi.mm16_m_format.opcode == mm_pool16c_op &&
-			 mmi.mm16_m_format.func == mm_swm16_op));
+	if (mm_insn_16bit(ip->word >> 16)) {
+		switch (ip->mm16_r5_format.opcode) {
+		case mm_swsp16_op:
+			if (ip->mm16_r5_format.rt != 31)
+				return 0;
+
+			*poff = ip->mm16_r5_format.imm;
+			*poff = (*poff << 2) / sizeof(ulong);
+			return 1;
+
+		case mm_pool16c_op:
+			switch (ip->mm16_m_format.func) {
+			case mm_swm16_op:
+				*poff = ip->mm16_m_format.imm;
+				*poff += 1 + ip->mm16_m_format.rlist;
+				*poff = (*poff << 2) / sizeof(ulong);
+				return 1;
+
+			default:
+				return 0;
+			}
+
+		default:
+			return 0;
+		}
 	}
-	else {
-		mmi.halfword[0] = ip->halfword[1];
-		mmi.halfword[1] = ip->halfword[0];
-		return ((mmi.mm_m_format.opcode == mm_pool32b_op &&
-			 mmi.mm_m_format.rd > 9 &&
-			 mmi.mm_m_format.base == 29 &&
-			 mmi.mm_m_format.func == mm_swm32_func) ||
-			(mmi.i_format.opcode == mm_sw32_op &&
-			 mmi.i_format.rs == 29 &&
-			 mmi.i_format.rt == 31));
+
+	switch (ip->i_format.opcode) {
+	case mm_sw32_op:
+		if (ip->i_format.rs != 29)
+			return 0;
+		if (ip->i_format.rt != 31)
+			return 0;
+
+		*poff = ip->i_format.simmediate / sizeof(ulong);
+		return 1;
+
+	case mm_pool32b_op:
+		switch (ip->mm_m_format.func) {
+		case mm_swm32_func:
+			if (ip->mm_m_format.rd < 0x10)
+				return 0;
+			if (ip->mm_m_format.base != 29)
+				return 0;
+
+			*poff = ip->mm_m_format.simmediate;
+			*poff += (ip->mm_m_format.rd & 0xf) * sizeof(u32);
+			*poff /= sizeof(ulong);
+			return 1;
+		default:
+			return 0;
+		}
+
+	default:
+		return 0;
 	}
 #else
 	/* sw / sd $ra, offset($sp) */
-	return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
-		ip->i_format.rs == 29 &&
-		ip->i_format.rt == 31;
+	if ((ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
+		ip->i_format.rs == 29 && ip->i_format.rt == 31) {
+		*poff = ip->i_format.simmediate / sizeof(ulong);
+		return 1;
+	}
+#ifdef CONFIG_CPU_LOONGSON64
+	if ((ip->loongson3_lswc2_format.opcode == swc2_op) &&
+		      (ip->loongson3_lswc2_format.ls == 1) &&
+		      (ip->loongson3_lswc2_format.fr == 0) &&
+		      (ip->loongson3_lswc2_format.base == 29)) {
+		if (ip->loongson3_lswc2_format.rt == 31) {
+			*poff = ip->loongson3_lswc2_format.offset << 1;
+			return 1;
+		}
+		if (ip->loongson3_lswc2_format.rq == 31) {
+			*poff = (ip->loongson3_lswc2_format.offset << 1) + 1;
+			return 1;
+		}
+	}
+#endif
+	return 0;
 #endif
 }
 
@@ -268,18 +325,21 @@ static inline int is_jump_ins(union mips_instruction *ip)
 	 *
 	 * microMIPS is kind of more fun...
 	 */
-	union mips_instruction mmi;
-
-	mmi.word = (ip->halfword[0] << 16);
+	if (mm_insn_16bit(ip->word >> 16)) {
+		if ((ip->mm16_r5_format.opcode == mm_pool16c_op &&
+		    (ip->mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op))
+			return 1;
+		return 0;
+	}
 
-	if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
-	    (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
-	    ip->j_format.opcode == mm_jal32_op)
+	if (ip->j_format.opcode == mm_j32_op)
+		return 1;
+	if (ip->j_format.opcode == mm_jal32_op)
 		return 1;
 	if (ip->r_format.opcode != mm_pool32a_op ||
 			ip->r_format.func != mm_pool32axf_op)
 		return 0;
-	return (((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op);
+	return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
 #else
 	if (ip->j_format.opcode == j_op)
 		return 1;
@@ -291,9 +351,11 @@ static inline int is_jump_ins(union mips_instruction *ip)
 #endif
 }
 
-static inline int is_sp_move_ins(union mips_instruction *ip)
+static inline int is_sp_move_ins(union mips_instruction *ip, int *frame_size)
 {
 #ifdef CONFIG_CPU_MICROMIPS
+	unsigned short tmp;
+
 	/*
 	 * addiusp -imm
 	 * addius5 sp,-imm
@@ -302,86 +364,107 @@ static inline int is_sp_move_ins(union mips_instruction *ip)
 	 *
 	 * microMIPS is not more fun...
 	 */
-	if (mm_insn_16bit(ip->halfword[0])) {
-		union mips_instruction mmi;
-
-		mmi.word = (ip->halfword[0] << 16);
-		return ((mmi.mm16_r3_format.opcode == mm_pool16d_op &&
-			 mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
-			(mmi.mm16_r5_format.opcode == mm_pool16d_op &&
-			 mmi.mm16_r5_format.rt == 29));
+	if (mm_insn_16bit(ip->word >> 16)) {
+		if (ip->mm16_r3_format.opcode == mm_pool16d_op &&
+		    ip->mm16_r3_format.simmediate & mm_addiusp_func) {
+			tmp = ip->mm_b0_format.simmediate >> 1;
+			tmp = ((tmp & 0x1ff) ^ 0x100) - 0x100;
+			if ((tmp + 2) < 4) /* 0x0,0x1,0x1fe,0x1ff are special */
+				tmp ^= 0x100;
+			*frame_size = -(signed short)(tmp << 2);
+			return 1;
+		}
+		if (ip->mm16_r5_format.opcode == mm_pool16d_op &&
+		    ip->mm16_r5_format.rt == 29) {
+			tmp = ip->mm16_r5_format.imm >> 1;
+			*frame_size = -(signed short)(tmp & 0xf);
+			return 1;
+		}
+		return 0;
+	}
+
+	if (ip->mm_i_format.opcode == mm_addiu32_op &&
+	    ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29) {
+		*frame_size = -ip->i_format.simmediate;
+		return 1;
 	}
-	return (ip->mm_i_format.opcode == mm_addiu32_op &&
-		 ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29);
 #else
 	/* addiu/daddiu sp,sp,-imm */
 	if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
 		return 0;
-	if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
+
+	if (ip->i_format.opcode == addiu_op ||
+	    ip->i_format.opcode == daddiu_op) {
+		*frame_size = -ip->i_format.simmediate;
 		return 1;
+	}
 #endif
 	return 0;
 }
 
 static int get_frame_info(struct mips_frame_info *info)
 {
-#ifdef CONFIG_CPU_MICROMIPS
-	union mips_instruction *ip = (void *) (((char *) info->func) - 1);
-#else
-	union mips_instruction *ip = info->func;
-#endif
-	unsigned max_insns = info->func_size / sizeof(union mips_instruction);
-	unsigned i;
+	bool is_mmips = IS_ENABLED(CONFIG_CPU_MICROMIPS);
+	union mips_instruction insn, *ip, *ip_end;
+	unsigned int last_insn_size = 0;
+	bool saw_jump = false;
 
 	info->pc_offset = -1;
 	info->frame_size = 0;
 
+	ip = (void *)msk_isa16_mode((ulong)info->func);
 	if (!ip)
 		goto err;
 
-	if (max_insns == 0)
-		max_insns = 128U;	/* unknown function size */
-	max_insns = min(128U, max_insns);
+	ip_end = (void *)ip + (info->func_size ? info->func_size : 512);
 
-	for (i = 0; i < max_insns; i++, ip++) {
+	while (ip < ip_end) {
+		ip = (void *)ip + last_insn_size;
+
+		if (is_mmips && mm_insn_16bit(ip->halfword[0])) {
+			insn.word = ip->halfword[0] << 16;
+			last_insn_size = 2;
+		} else if (is_mmips) {
+			insn.word = ip->halfword[0] << 16 | ip->halfword[1];
+			last_insn_size = 4;
+		} else {
+			insn.word = ip->word;
+			last_insn_size = 4;
+		}
 
-		if (is_jump_ins(ip))
+		if (is_jr_ra_ins(ip)) {
 			break;
-		if (!info->frame_size) {
-			if (is_sp_move_ins(ip))
-			{
-#ifdef CONFIG_CPU_MICROMIPS
-				if (mm_insn_16bit(ip->halfword[0]))
-				{
-					unsigned short tmp;
-
-					if (ip->halfword[0] & mm_addiusp_func)
-					{
-						tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
-						info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
-					} else {
-						tmp = (ip->halfword[0] >> 1);
-						info->frame_size = -(signed short)(tmp & 0xf);
-					}
-					ip = (void *) &ip->halfword[1];
-					ip--;
-				} else
-#endif
-				info->frame_size = - ip->i_format.simmediate;
-			}
+		} else if (!info->frame_size) {
+			is_sp_move_ins(&insn, &info->frame_size);
+			continue;
+		} else if (!saw_jump && is_jump_ins(ip)) {
+			/*
+			 * If we see a jump instruction, we are finished
+			 * with the frame save.
+			 *
+			 * Some functions can have a shortcut return at
+			 * the beginning of the function, so don't start
+			 * looking for jump instruction until we see the
+			 * frame setup.
+			 *
+			 * The RA save instruction can get put into the
+			 * delay slot of the jump instruction, so look
+			 * at the next instruction, too.
+			 */
+			saw_jump = true;
 			continue;
 		}
-		if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
-			info->pc_offset =
-				ip->i_format.simmediate / sizeof(long);
+		if (info->pc_offset == -1 &&
+		    is_ra_save_ins(&insn, &info->pc_offset))
+			break;
+		if (saw_jump)
 			break;
-		}
 	}
 	if (info->frame_size && info->pc_offset >= 0) /* nested */
 		return 0;
 	if (info->pc_offset < 0) /* leaf */
 		return 1;
-	/* prologue seems boggus... */
+	/* prologue seems bogus... */
 err:
 	return -1;
 }
@@ -430,7 +513,7 @@ static int __init frame_info_init(void)
 
 	/*
 	 * Without schedule() frame info, result given by
-	 * thread_saved_pc() and get_wchan() are not reliable.
+	 * thread_saved_pc() and __get_wchan() are not reliable.
 	 */
 	if (schedule_mfi.pc_offset < 0)
 		printk("Can't analyze schedule() prologue at %p\n", schedule);
@@ -443,7 +526,7 @@ arch_initcall(frame_info_init);
 /*
  * Return saved PC of a blocked thread.
  */
-unsigned long thread_saved_pc(struct task_struct *tsk)
+static unsigned long thread_saved_pc(struct task_struct *tsk)
 {
 	struct thread_struct *t = &tsk->thread;
 
@@ -463,31 +546,52 @@ unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
 					      unsigned long pc,
 					      unsigned long *ra)
 {
+	unsigned long low, high, irq_stack_high;
 	struct mips_frame_info info;
 	unsigned long size, ofs;
+	struct pt_regs *regs;
 	int leaf;
-	extern void ret_from_irq(void);
-	extern void ret_from_exception(void);
 
 	if (!stack_page)
 		return 0;
 
 	/*
-	 * If we reached the bottom of interrupt context,
-	 * return saved pc in pt_regs.
+	 * IRQ stacks start at IRQ_STACK_START
+	 * task stacks at THREAD_SIZE - 32
 	 */
-	if (pc == (unsigned long)ret_from_irq ||
-	    pc == (unsigned long)ret_from_exception) {
-		struct pt_regs *regs;
-		if (*sp >= stack_page &&
-		    *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
-			regs = (struct pt_regs *)*sp;
-			pc = regs->cp0_epc;
-			if (__kernel_text_address(pc)) {
-				*sp = regs->regs[29];
-				*ra = regs->regs[31];
-				return pc;
-			}
+	low = stack_page;
+	if (!preemptible() && on_irq_stack(raw_smp_processor_id(), *sp)) {
+		high = stack_page + IRQ_STACK_START;
+		irq_stack_high = high;
+	} else {
+		high = stack_page + THREAD_SIZE - 32;
+		irq_stack_high = 0;
+	}
+
+	/*
+	 * If we reached the top of the interrupt stack, start unwinding
+	 * the interrupted task stack.
+	 */
+	if (unlikely(*sp == irq_stack_high)) {
+		unsigned long task_sp = *(unsigned long *)*sp;
+
+		/*
+		 * Check that the pointer saved in the IRQ stack head points to
+		 * something within the stack of the current task
+		 */
+		if (!object_is_on_stack((void *)task_sp))
+			return 0;
+
+		/*
+		 * Follow pointer to tasks kernel stack frame where interrupted
+		 * state was saved.
+		 */
+		regs = (struct pt_regs *)task_sp;
+		pc = regs->cp0_epc;
+		if (!user_mode(regs) && __kernel_text_address(pc)) {
+			*sp = regs->regs[29];
+			*ra = regs->regs[31];
+			return pc;
 		}
 		return 0;
 	}
@@ -508,8 +612,7 @@ unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
 	if (leaf < 0)
 		return 0;
 
-	if (*sp < stack_page ||
-	    *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
+	if (*sp < low || *sp + info.frame_size > high)
 		return 0;
 
 	if (leaf)
@@ -533,15 +636,27 @@ EXPORT_SYMBOL(unwind_stack_by_address);
 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
 			   unsigned long pc, unsigned long *ra)
 {
-	unsigned long stack_page = (unsigned long)task_stack_page(task);
+	unsigned long stack_page = 0;
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		if (on_irq_stack(cpu, *sp)) {
+			stack_page = (unsigned long)irq_stack[cpu];
+			break;
+		}
+	}
+
+	if (!stack_page)
+		stack_page = (unsigned long)task_stack_page(task);
+
 	return unwind_stack_by_address(stack_page, sp, pc, ra);
 }
 #endif
 
 /*
- * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
+ * __get_wchan - a maintenance nightmare^W^Wpain in the ass ...
  */
-unsigned long get_wchan(struct task_struct *task)
+unsigned long __get_wchan(struct task_struct *task)
 {
 	unsigned long pc = 0;
 #ifdef CONFIG_KALLSYMS
@@ -549,8 +664,6 @@ unsigned long get_wchan(struct task_struct *task)
 	unsigned long ra = 0;
 #endif
 
-	if (!task || task == current || task->state == TASK_RUNNING)
-		goto out;
 	if (!task_stack_page(task))
 		goto out;
 
@@ -567,6 +680,33 @@ out:
 	return pc;
 }
 
+unsigned long mips_stack_top(void)
+{
+	unsigned long top = TASK_SIZE & PAGE_MASK;
+
+	if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) {
+		/* One page for branch delay slot "emulation" */
+		top -= PAGE_SIZE;
+	}
+
+	/* Space for the VDSO, data page & GIC user page */
+	if (current->thread.abi) {
+		top -= PAGE_ALIGN(current->thread.abi->vdso->size);
+		top -= VDSO_NR_PAGES * PAGE_SIZE;
+		top -= mips_gic_present() ? PAGE_SIZE : 0;
+
+		/* Space to randomize the VDSO base */
+		if (current->flags & PF_RANDOMIZE)
+			top -= VDSO_RANDOMIZE_SIZE;
+	}
+
+	/* Space for cache colour alignment */
+	if (cpu_has_dc_aliases)
+		top -= shm_align_mask + 1;
+
+	return top;
+}
+
 /*
  * Don't forget that the stack pointer must be aligned on a 8 bytes
  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
@@ -574,7 +714,201 @@ out:
 unsigned long arch_align_stack(unsigned long sp)
 {
 	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
-		sp -= get_random_int() & ~PAGE_MASK;
+		sp -= get_random_u32_below(PAGE_SIZE);
 
 	return sp & ALMASK;
 }
+
+static struct cpumask backtrace_csd_busy;
+
+static void handle_backtrace(void *info)
+{
+	nmi_cpu_backtrace(get_irq_regs());
+	cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
+}
+
+static DEFINE_PER_CPU(call_single_data_t, backtrace_csd) =
+	CSD_INIT(handle_backtrace, NULL);
+
+static void raise_backtrace(cpumask_t *mask)
+{
+	call_single_data_t *csd;
+	int cpu;
+
+	for_each_cpu(cpu, mask) {
+		/*
+		 * If we previously sent an IPI to the target CPU & it hasn't
+		 * cleared its bit in the busy cpumask then it didn't handle
+		 * our previous IPI & it's not safe for us to reuse the
+		 * call_single_data_t.
+		 */
+		if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) {
+			pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
+				cpu);
+			continue;
+		}
+
+		csd = &per_cpu(backtrace_csd, cpu);
+		smp_call_function_single_async(cpu, csd);
+	}
+}
+
+void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
+{
+	nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_backtrace);
+}
+
+int mips_get_process_fp_mode(struct task_struct *task)
+{
+	int value = 0;
+
+	if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
+		value |= PR_FP_MODE_FR;
+	if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
+		value |= PR_FP_MODE_FRE;
+
+	return value;
+}
+
+static long prepare_for_fp_mode_switch(void *unused)
+{
+	/*
+	 * This is icky, but we use this to simply ensure that all CPUs have
+	 * context switched, regardless of whether they were previously running
+	 * kernel or user code. This ensures that no CPU that a mode-switching
+	 * program may execute on keeps its FPU enabled (& in the old mode)
+	 * throughout the mode switch.
+	 */
+	return 0;
+}
+
+int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
+{
+	const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
+	struct task_struct *t;
+	struct cpumask process_cpus;
+	int cpu;
+
+	/* If nothing to change, return right away, successfully.  */
+	if (value == mips_get_process_fp_mode(task))
+		return 0;
+
+	/* Only accept a mode change if 64-bit FP enabled for o32.  */
+	if (!IS_ENABLED(CONFIG_MIPS_O32_FP64_SUPPORT))
+		return -EOPNOTSUPP;
+
+	/* And only for o32 tasks.  */
+	if (IS_ENABLED(CONFIG_64BIT) && !test_thread_flag(TIF_32BIT_REGS))
+		return -EOPNOTSUPP;
+
+	/* Check the value is valid */
+	if (value & ~known_bits)
+		return -EOPNOTSUPP;
+
+	/* Setting FRE without FR is not supported.  */
+	if ((value & (PR_FP_MODE_FR | PR_FP_MODE_FRE)) == PR_FP_MODE_FRE)
+		return -EOPNOTSUPP;
+
+	/* Avoid inadvertently triggering emulation */
+	if ((value & PR_FP_MODE_FR) && raw_cpu_has_fpu &&
+	    !(raw_current_cpu_data.fpu_id & MIPS_FPIR_F64))
+		return -EOPNOTSUPP;
+	if ((value & PR_FP_MODE_FRE) && raw_cpu_has_fpu && !cpu_has_fre)
+		return -EOPNOTSUPP;
+
+	/* FR = 0 not supported in MIPS R6 */
+	if (!(value & PR_FP_MODE_FR) && raw_cpu_has_fpu && cpu_has_mips_r6)
+		return -EOPNOTSUPP;
+
+	/* Indicate the new FP mode in each thread */
+	for_each_thread(task, t) {
+		/* Update desired FP register width */
+		if (value & PR_FP_MODE_FR) {
+			clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
+		} else {
+			set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
+			clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
+		}
+
+		/* Update desired FP single layout */
+		if (value & PR_FP_MODE_FRE)
+			set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
+		else
+			clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
+	}
+
+	/*
+	 * We need to ensure that all threads in the process have switched mode
+	 * before returning, in order to allow userland to not worry about
+	 * races. We can do this by forcing all CPUs that any thread in the
+	 * process may be running on to schedule something else - in this case
+	 * prepare_for_fp_mode_switch().
+	 *
+	 * We begin by generating a mask of all CPUs that any thread in the
+	 * process may be running on.
+	 */
+	cpumask_clear(&process_cpus);
+	for_each_thread(task, t)
+		cpumask_set_cpu(task_cpu(t), &process_cpus);
+
+	/*
+	 * Now we schedule prepare_for_fp_mode_switch() on each of those CPUs.
+	 *
+	 * The CPUs may have rescheduled already since we switched mode or
+	 * generated the cpumask, but that doesn't matter. If the task in this
+	 * process is scheduled out then our scheduling
+	 * prepare_for_fp_mode_switch() will simply be redundant. If it's
+	 * scheduled in then it will already have picked up the new FP mode
+	 * whilst doing so.
+	 */
+	cpus_read_lock();
+	for_each_cpu_and(cpu, &process_cpus, cpu_online_mask)
+		work_on_cpu(cpu, prepare_for_fp_mode_switch, NULL);
+	cpus_read_unlock();
+
+	return 0;
+}
+
+#if defined(CONFIG_32BIT) || defined(CONFIG_MIPS32_O32)
+void mips_dump_regs32(u32 *uregs, const struct pt_regs *regs)
+{
+	unsigned int i;
+
+	for (i = MIPS32_EF_R1; i <= MIPS32_EF_R31; i++) {
+		/* k0/k1 are copied as zero. */
+		if (i == MIPS32_EF_R26 || i == MIPS32_EF_R27)
+			uregs[i] = 0;
+		else
+			uregs[i] = regs->regs[i - MIPS32_EF_R0];
+	}
+
+	uregs[MIPS32_EF_LO] = regs->lo;
+	uregs[MIPS32_EF_HI] = regs->hi;
+	uregs[MIPS32_EF_CP0_EPC] = regs->cp0_epc;
+	uregs[MIPS32_EF_CP0_BADVADDR] = regs->cp0_badvaddr;
+	uregs[MIPS32_EF_CP0_STATUS] = regs->cp0_status;
+	uregs[MIPS32_EF_CP0_CAUSE] = regs->cp0_cause;
+}
+#endif /* CONFIG_32BIT || CONFIG_MIPS32_O32 */
+
+#ifdef CONFIG_64BIT
+void mips_dump_regs64(u64 *uregs, const struct pt_regs *regs)
+{
+	unsigned int i;
+
+	for (i = MIPS64_EF_R1; i <= MIPS64_EF_R31; i++) {
+		/* k0/k1 are copied as zero. */
+		if (i == MIPS64_EF_R26 || i == MIPS64_EF_R27)
+			uregs[i] = 0;
+		else
+			uregs[i] = regs->regs[i - MIPS64_EF_R0];
+	}
+
+	uregs[MIPS64_EF_LO] = regs->lo;
+	uregs[MIPS64_EF_HI] = regs->hi;
+	uregs[MIPS64_EF_CP0_EPC] = regs->cp0_epc;
+	uregs[MIPS64_EF_CP0_BADVADDR] = regs->cp0_badvaddr;
+	uregs[MIPS64_EF_CP0_STATUS] = regs->cp0_status;
+	uregs[MIPS64_EF_CP0_CAUSE] = regs->cp0_cause;
+}
+#endif /* CONFIG_64BIT */