1 files changed, 393 insertions, 248 deletions

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index fa98f10d013..0a1ec0f3bef 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -4,34 +4,36 @@
  * for more details.
  *
  * Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others.
+ * Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org)
  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
  * Copyright (C) 2004 Thiemo Seufer
+ * Copyright (C) 2013  Imagination Technologies Ltd.
  */
-#include <linux/config.h>
 #include <linux/errno.h>
-#include <linux/module.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/slab.h>
 #include <linux/mman.h>
 #include <linux/personality.h>
 #include <linux/sys.h>
 #include <linux/user.h>
-#include <linux/a.out.h>
 #include <linux/init.h>
 #include <linux/completion.h>
+#include <linux/kallsyms.h>
+#include <linux/random.h>
 
-#include <asm/abi.h>
+#include <asm/asm.h>
 #include <asm/bootinfo.h>
 #include <asm/cpu.h>
 #include <asm/dsp.h>
 #include <asm/fpu.h>
+#include <asm/msa.h>
 #include <asm/pgtable.h>
-#include <asm/system.h>
 #include <asm/mipsregs.h>
 #include <asm/processor.h>
 #include <asm/uaccess.h>
@@ -39,94 +41,35 @@
 #include <asm/elf.h>
 #include <asm/isadep.h>
 #include <asm/inst.h>
+#include <asm/stacktrace.h>
 
-/*
- * The idle thread. There's no useful work to be done, so just try to conserve
- * power and have a low exit latency (ie sit in a loop waiting for somebody to
- * say that they'd like to reschedule)
- */
-ATTRIB_NORET void cpu_idle(void)
+#ifdef CONFIG_HOTPLUG_CPU
+void arch_cpu_idle_dead(void)
 {
-	/* endless idle loop with no priority at all */
-	while (1) {
-		while (!need_resched())
-			if (cpu_wait)
-				(*cpu_wait)();
-		preempt_enable_no_resched();
-		schedule();
-		preempt_disable();
-	}
+	/* What the heck is this check doing ? */
+	if (!cpu_isset(smp_processor_id(), cpu_callin_map))
+		play_dead();
 }
-
-extern int do_signal(sigset_t *oldset, struct pt_regs *regs);
-extern int do_signal32(sigset_t *oldset, struct pt_regs *regs);
-
-/*
- * Native o32 and N64 ABI without DSP ASE
- */
-extern int setup_frame(struct k_sigaction * ka, struct pt_regs *regs,
-        int signr, sigset_t *set);
-extern int setup_rt_frame(struct k_sigaction * ka, struct pt_regs *regs,
-        int signr, sigset_t *set, siginfo_t *info);
-
-struct mips_abi mips_abi = {
-	.do_signal	= do_signal,
-#ifdef CONFIG_TRAD_SIGNALS
-	.setup_frame	= setup_frame,
 #endif
-	.setup_rt_frame	= setup_rt_frame
-};
-
-#ifdef CONFIG_MIPS32_O32
-/*
- * o32 compatibility on 64-bit kernels, without DSP ASE
- */
-extern int setup_frame_32(struct k_sigaction * ka, struct pt_regs *regs,
-        int signr, sigset_t *set);
-extern int setup_rt_frame_32(struct k_sigaction * ka, struct pt_regs *regs,
-        int signr, sigset_t *set, siginfo_t *info);
-
-struct mips_abi mips_abi_32 = {
-	.do_signal	= do_signal32,
-	.setup_frame	= setup_frame_32,
-	.setup_rt_frame	= setup_rt_frame_32
-};
-#endif /* CONFIG_MIPS32_O32 */
-
-#ifdef CONFIG_MIPS32_N32
-/*
- * N32 on 64-bit kernels, without DSP ASE
- */
-extern int setup_rt_frame_n32(struct k_sigaction * ka, struct pt_regs *regs,
-        int signr, sigset_t *set, siginfo_t *info);
-
-struct mips_abi mips_abi_n32 = {
-	.do_signal	= do_signal,
-	.setup_rt_frame	= setup_rt_frame_n32
-};
-#endif /* CONFIG_MIPS32_N32 */
 
 asmlinkage void ret_from_fork(void);
+asmlinkage void ret_from_kernel_thread(void);
 
 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|KU_MASK);
-#ifdef CONFIG_64BIT
-	status &= ~ST0_FR;
-	status |= (current->thread.mflags & MF_32BIT_REGS) ? 0 : ST0_FR;
-#endif
+	status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
 	status |= KU_USER;
 	regs->cp0_status = status;
 	clear_used_math();
-	lose_fpu();
-	if (cpu_has_dsp)
-		__init_dsp();
+	clear_fpu_owner();
+	init_dsp();
+	clear_thread_flag(TIF_MSA_CTX_LIVE);
+	disable_msa();
 	regs->cp0_epc = pc;
 	regs->regs[29] = sp;
-	current_thread_info()->addr_limit = USER_DS;
 }
 
 void exit_thread(void)
@@ -137,19 +80,21 @@ void flush_thread(void)
 {
 }
 
-int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
-	unsigned long unused, struct task_struct *p, struct pt_regs *regs)
+int copy_thread(unsigned long clone_flags, unsigned long usp,
+	unsigned long arg, struct task_struct *p)
 {
 	struct thread_info *ti = task_thread_info(p);
-	struct pt_regs *childregs;
-	long childksp;
+	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())
+	if (is_msa_enabled())
+		save_msa(p);
+	else if (is_fpu_owner())
 		save_fp(p);
 
 	if (cpu_has_dsp)
@@ -159,27 +104,33 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
 
 	/* set up new TSS. */
 	childregs = (struct pt_regs *) childksp - 1;
-	*childregs = *regs;
-	childregs->regs[7] = 0;	/* Clear error flag */
-
-#if defined(CONFIG_BINFMT_IRIX)
-	if (current->personality != PER_LINUX) {
-		/* Under IRIX things are a little different. */
-		childregs->regs[3] = 1;
-		regs->regs[3] = 0;
-	}
-#endif
-	childregs->regs[2] = 0;	/* Child gets zero as return value */
-	regs->regs[2] = p->pid;
-
-	if (childregs->cp0_status & ST0_CU0) {
-		childregs->regs[28] = (unsigned long) ti;
-		childregs->regs[29] = childksp;
+	/*  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)) {
+		unsigned long status = p->thread.cp0_status;
+		memset(childregs, 0, sizeof(struct pt_regs));
 		ti->addr_limit = KERNEL_DS;
-	} else {
-		childregs->regs[29] = usp;
-		ti->addr_limit = USER_DS;
+		p->thread.reg16 = usp; /* fn */
+		p->thread.reg17 = arg;
+		p->thread.reg29 = childksp;
+		p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
+#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
+		status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
+			 ((status & (ST0_KUC | ST0_IEC)) << 2);
+#else
+		status |= ST0_EXL;
+#endif
+		childregs->cp0_status = status;
+		return 0;
 	}
+	*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;
 
@@ -187,10 +138,14 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
 	 * New tasks lose permission to use the fpu. This accelerates context
 	 * switching for most programs since they don't use the fpu.
 	 */
-	p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
 	childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
+
 	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];
 
@@ -200,7 +155,13 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
 /* 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));
+	int i;
+
+	for (i = 0; i < NUM_FPU_REGS; i++)
+		memcpy(&r[i], &current->thread.fpu.fpr[i], sizeof(*r));
+
+	memcpy(&r[NUM_FPU_REGS], &current->thread.fpu.fcr31,
+	       sizeof(current->thread.fpu.fcr31));
 
 	return 1;
 }
@@ -227,156 +188,259 @@ void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs)
 #endif
 }
 
-int dump_task_regs (struct task_struct *tsk, elf_gregset_t *regs)
+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)
+int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr)
 {
-	memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
+	int i;
+
+	for (i = 0; i < NUM_FPU_REGS; i++)
+		memcpy(&fpr[i], &t->thread.fpu.fpr[i], sizeof(*fpr));
+
+	memcpy(&fpr[NUM_FPU_REGS], &t->thread.fpu.fcr31,
+	       sizeof(t->thread.fpu.fcr31));
 
 	return 1;
 }
 
-/*
- * Create a kernel thread
- */
-ATTRIB_NORET void kernel_thread_helper(void *arg, int (*fn)(void *))
+#ifdef CONFIG_CC_STACKPROTECTOR
+#include <linux/stackprotector.h>
+unsigned long __stack_chk_guard __read_mostly;
+EXPORT_SYMBOL(__stack_chk_guard);
+#endif
+
+struct mips_frame_info {
+	void		*func;
+	unsigned long	func_size;
+	int		frame_size;
+	int		pc_offset;
+};
+
+#define J_TARGET(pc,target)	\
+		(((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
+
+static inline int is_ra_save_ins(union mips_instruction *ip)
 {
-	do_exit(fn(arg));
+#ifdef CONFIG_CPU_MICROMIPS
+	union mips_instruction mmi;
+
+	/*
+	 * swsp ra,offset
+	 * swm16 reglist,offset(sp)
+	 * swm32 reglist,offset(sp)
+	 * sw32 ra,offset(sp)
+	 * jradiussp - NOT SUPPORTED
+	 *
+	 * 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));
+	}
+	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));
+	}
+#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;
+#endif
 }
 
-long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
+static inline int is_jump_ins(union mips_instruction *ip)
 {
-	struct pt_regs regs;
+#ifdef CONFIG_CPU_MICROMIPS
+	/*
+	 * jr16,jrc,jalr16,jalr16
+	 * jal
+	 * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
+	 * jraddiusp - NOT SUPPORTED
+	 *
+	 * microMIPS is kind of more fun...
+	 */
+	union mips_instruction mmi;
 
-	memset(&regs, 0, sizeof(regs));
+	mmi.word = (ip->halfword[0] << 16);
 
-	regs.regs[4] = (unsigned long) arg;
-	regs.regs[5] = (unsigned long) fn;
-	regs.cp0_epc = (unsigned long) kernel_thread_helper;
-	regs.cp0_status = read_c0_status();
-#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
-	regs.cp0_status &= ~(ST0_KUP | ST0_IEC);
-	regs.cp0_status |= ST0_IEP;
+	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)
+		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);
 #else
-	regs.cp0_status |= ST0_EXL;
+	if (ip->j_format.opcode == j_op)
+		return 1;
+	if (ip->j_format.opcode == jal_op)
+		return 1;
+	if (ip->r_format.opcode != spec_op)
+		return 0;
+	return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
 #endif
-
-	/* Ok, create the new process.. */
-	return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
 }
 
-static struct mips_frame_info {
-	void *func;
-	int omit_fp;	/* compiled without fno-omit-frame-pointer */
-	int frame_offset;
-	int pc_offset;
-} schedule_frame, mfinfo[] = {
-	{ schedule, 0 },	/* must be first */
-	/* arch/mips/kernel/semaphore.c */
-	{ __down, 1 },
-	{ __down_interruptible, 1 },
-	/* kernel/sched.c */
-#ifdef CONFIG_PREEMPT
-	{ preempt_schedule, 0 },
-#endif
-	{ wait_for_completion, 0 },
-	{ interruptible_sleep_on, 0 },
-	{ interruptible_sleep_on_timeout, 0 },
-	{ sleep_on, 0 },
-	{ sleep_on_timeout, 0 },
-	{ yield, 0 },
-	{ io_schedule, 0 },
-	{ io_schedule_timeout, 0 },
-#if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT)
-	{ __preempt_spin_lock, 0 },
-	{ __preempt_write_lock, 0 },
+static inline int is_sp_move_ins(union mips_instruction *ip)
+{
+#ifdef CONFIG_CPU_MICROMIPS
+	/*
+	 * addiusp -imm
+	 * addius5 sp,-imm
+	 * addiu32 sp,sp,-imm
+	 * jradiussp - NOT SUPPORTED
+	 *
+	 * 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));
+	}
+	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)
+		return 1;
 #endif
-	/* kernel/timer.c */
-	{ schedule_timeout, 1 },
-/*	{ nanosleep_restart, 1 }, */
-	/* lib/rwsem-spinlock.c */
-	{ __down_read, 1 },
-	{ __down_write, 1 },
-};
+	return 0;
+}
 
-static int mips_frame_info_initialized;
-static int __init get_frame_info(struct mips_frame_info *info)
+static int get_frame_info(struct mips_frame_info *info)
 {
-	int i;
-	void *func = info->func;
-	union mips_instruction *ip = (union mips_instruction *)func;
+#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;
+
 	info->pc_offset = -1;
-	info->frame_offset = info->omit_fp ? 0 : -1;
-	for (i = 0; i < 128; i++, ip++) {
-		/* if jal, jalr, jr, stop. */
-		if (ip->j_format.opcode == jal_op ||
-		    (ip->r_format.opcode == spec_op &&
-		     (ip->r_format.func == jalr_op ||
-		      ip->r_format.func == jr_op)))
-			break;
+	info->frame_size = 0;
 
-		if (
-#ifdef CONFIG_32BIT
-		    ip->i_format.opcode == sw_op &&
-#endif
-#ifdef CONFIG_64BIT
-		    ip->i_format.opcode == sd_op &&
+	if (!ip)
+		goto err;
+
+	if (max_insns == 0)
+		max_insns = 128U;	/* unknown function size */
+	max_insns = min(128U, max_insns);
+
+	for (i = 0; i < max_insns; i++, ip++) {
+
+		if (is_jump_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
-		    ip->i_format.rs == 29)
-		{
-			/* sw / sd $ra, offset($sp) */
-			if (ip->i_format.rt == 31) {
-				if (info->pc_offset != -1)
-					continue;
-				info->pc_offset =
-					ip->i_format.simmediate / sizeof(long);
-			}
-			/* sw / sd $s8, offset($sp) */
-			if (ip->i_format.rt == 30) {
-//#if 0	/* gcc 3.4 does aggressive optimization... */
-				if (info->frame_offset != -1)
-					continue;
-//#endif
-				info->frame_offset =
-					ip->i_format.simmediate / sizeof(long);
+				info->frame_size = - ip->i_format.simmediate;
 			}
+			continue;
+		}
+		if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
+			info->pc_offset =
+				ip->i_format.simmediate / sizeof(long);
+			break;
 		}
 	}
-	if (info->pc_offset == -1 || info->frame_offset == -1) {
-		printk("Can't analyze prologue code at %p\n", func);
-		info->pc_offset = -1;
-		info->frame_offset = -1;
-		return -1;
-	}
+	if (info->frame_size && info->pc_offset >= 0) /* nested */
+		return 0;
+	if (info->pc_offset < 0) /* leaf */
+		return 1;
+	/* prologue seems boggus... */
+err:
+	return -1;
+}
+
+static struct mips_frame_info schedule_mfi __read_mostly;
+
+#ifdef CONFIG_KALLSYMS
+static unsigned long get___schedule_addr(void)
+{
+	return kallsyms_lookup_name("__schedule");
+}
+#else
+static unsigned long get___schedule_addr(void)
+{
+	union mips_instruction *ip = (void *)schedule;
+	int max_insns = 8;
+	int i;
 
+	for (i = 0; i < max_insns; i++, ip++) {
+		if (ip->j_format.opcode == j_op)
+			return J_TARGET(ip, ip->j_format.target);
+	}
 	return 0;
 }
+#endif
 
 static int __init frame_info_init(void)
 {
-	int i, found;
-	for (i = 0; i < ARRAY_SIZE(mfinfo); i++)
-		if (get_frame_info(&mfinfo[i]))
-			return -1;
-	schedule_frame = mfinfo[0];
-	/* bubble sort */
-	do {
-		struct mips_frame_info tmp;
-		found = 0;
-		for (i = 1; i < ARRAY_SIZE(mfinfo); i++) {
-			if (mfinfo[i-1].func > mfinfo[i].func) {
-				tmp = mfinfo[i];
-				mfinfo[i] = mfinfo[i-1];
-				mfinfo[i-1] = tmp;
-				found = 1;
-			}
-		}
-	} while (found);
-	mips_frame_info_initialized = 1;
+	unsigned long size = 0;
+#ifdef CONFIG_KALLSYMS
+	unsigned long ofs;
+#endif
+	unsigned long addr;
+
+	addr = get___schedule_addr();
+	if (!addr)
+		addr = (unsigned long)schedule;
+
+#ifdef CONFIG_KALLSYMS
+	kallsyms_lookup_size_offset(addr, &size, &ofs);
+#endif
+	schedule_mfi.func = (void *)addr;
+	schedule_mfi.func_size = size;
+
+	get_frame_info(&schedule_mfi);
+
+	/*
+	 * Without schedule() frame info, result given by
+	 * 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);
+
 	return 0;
 }
 
@@ -392,50 +456,131 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
 	/* New born processes are a special case */
 	if (t->reg31 == (unsigned long) ret_from_fork)
 		return t->reg31;
-
-	if (schedule_frame.pc_offset < 0)
+	if (schedule_mfi.pc_offset < 0)
 		return 0;
-	return ((unsigned long *)t->reg29)[schedule_frame.pc_offset];
+	return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
 }
 
-/* get_wchan - a maintenance nightmare^W^Wpain in the ass ...  */
-unsigned long get_wchan(struct task_struct *p)
+
+#ifdef CONFIG_KALLSYMS
+/* generic stack unwinding function */
+unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
+					      unsigned long *sp,
+					      unsigned long pc,
+					      unsigned long *ra)
 {
-	unsigned long stack_page;
-	unsigned long frame, pc;
+	struct mips_frame_info info;
+	unsigned long size, ofs;
+	int leaf;
+	extern void ret_from_irq(void);
+	extern void ret_from_exception(void);
 
-	if (!p || p == current || p->state == TASK_RUNNING)
+	if (!stack_page)
 		return 0;
 
-	stack_page = (unsigned long)task_stack_page(p);
-	if (!stack_page || !mips_frame_info_initialized)
+	/*
+	 * If we reached the bottom of interrupt context,
+	 * return saved pc in pt_regs.
+	 */
+	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;
+			}
+		}
 		return 0;
-
-	pc = thread_saved_pc(p);
-	if (!in_sched_functions(pc))
+	}
+	if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
+		return 0;
+	/*
+	 * Return ra if an exception occurred at the first instruction
+	 */
+	if (unlikely(ofs == 0)) {
+		pc = *ra;
+		*ra = 0;
 		return pc;
+	}
 
-	frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
-	do {
-		int i;
+	info.func = (void *)(pc - ofs);
+	info.func_size = ofs;	/* analyze from start to ofs */
+	leaf = get_frame_info(&info);
+	if (leaf < 0)
+		return 0;
 
-		if (frame < stack_page || frame > stack_page + THREAD_SIZE - 32)
-			return 0;
+	if (*sp < stack_page ||
+	    *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
+		return 0;
 
-		for (i = ARRAY_SIZE(mfinfo) - 1; i >= 0; i--) {
-			if (pc >= (unsigned long) mfinfo[i].func)
-				break;
-		}
-		if (i < 0)
-			break;
+	if (leaf)
+		/*
+		 * For some extreme cases, get_frame_info() can
+		 * consider wrongly a nested function as a leaf
+		 * one. In that cases avoid to return always the
+		 * same value.
+		 */
+		pc = pc != *ra ? *ra : 0;
+	else
+		pc = ((unsigned long *)(*sp))[info.pc_offset];
+
+	*sp += info.frame_size;
+	*ra = 0;
+	return __kernel_text_address(pc) ? pc : 0;
+}
+EXPORT_SYMBOL(unwind_stack_by_address);
 
-		if (mfinfo[i].omit_fp)
-			break;
-		pc = ((unsigned long *)frame)[mfinfo[i].pc_offset];
-		frame = ((unsigned long *)frame)[mfinfo[i].frame_offset];
-	} while (in_sched_functions(pc));
+/* used by show_backtrace() */
+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);
+	return unwind_stack_by_address(stack_page, sp, pc, ra);
+}
+#endif
+
+/*
+ * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
+ */
+unsigned long get_wchan(struct task_struct *task)
+{
+	unsigned long pc = 0;
+#ifdef CONFIG_KALLSYMS
+	unsigned long sp;
+	unsigned long ra = 0;
+#endif
+
+	if (!task || task == current || task->state == TASK_RUNNING)
+		goto out;
+	if (!task_stack_page(task))
+		goto out;
 
+	pc = thread_saved_pc(task);
+
+#ifdef CONFIG_KALLSYMS
+	sp = task->thread.reg29 + schedule_mfi.frame_size;
+
+	while (in_sched_functions(pc))
+		pc = unwind_stack(task, &sp, pc, &ra);
+#endif
+
+out:
 	return pc;
 }
 
-EXPORT_SYMBOL(get_wchan);
+/*
+ * 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.
+ */
+unsigned long arch_align_stack(unsigned long sp)
+{
+	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
+		sp -= get_random_int() & ~PAGE_MASK;
+
+	return sp & ALMASK;
+}