17 files changed, 125 insertions, 141 deletions

diff --git a/arch/arc/kernel/ctx_sw.c b/arch/arc/kernel/ctx_sw.c
index 34410eb1a30..c14a5bea0c7 100644
--- a/arch/arc/kernel/ctx_sw.c
+++ b/arch/arc/kernel/ctx_sw.c
@@ -17,6 +17,8 @@
 #include <asm/asm-offsets.h>
 #include <linux/sched.h>
 
+#define KSP_WORD_OFF 	((TASK_THREAD + THREAD_KSP) / 4)
+
 struct task_struct *__sched
 __switch_to(struct task_struct *prev_task, struct task_struct *next_task)
 {
@@ -45,7 +47,16 @@ __switch_to(struct task_struct *prev_task, struct task_struct *next_task)
 #endif
 
 		/* set ksp of outgoing task in tsk->thread.ksp */
+#if KSP_WORD_OFF <= 255
 		"st.as   sp, [%3, %1]    \n\t"
+#else
+		/*
+		 * Workaround for NR_CPUS=4k
+		 * %1 is bigger than 255 (S9 offset for st.as)
+		 */
+		"add2    r24, %3, %1     \n\t"
+		"st      sp, [r24]       \n\t"
+#endif
 
 		"sync   \n\t"
 
@@ -97,7 +108,7 @@ __switch_to(struct task_struct *prev_task, struct task_struct *next_task)
 		/* FP/BLINK restore generated by gcc (standard func epilogue */
 
 		: "=r"(tmp)
-		: "n"((TASK_THREAD + THREAD_KSP) / 4), "r"(next), "r"(prev)
+		: "n"(KSP_WORD_OFF), "r"(next), "r"(prev)
 		: "blink"
 	);
 
diff --git a/arch/arc/kernel/ctx_sw_asm.S b/arch/arc/kernel/ctx_sw_asm.S
index d8972345e4c..65690e7fcc8 100644
--- a/arch/arc/kernel/ctx_sw_asm.S
+++ b/arch/arc/kernel/ctx_sw_asm.S
@@ -14,6 +14,8 @@
 #include <asm/asm-offsets.h>
 #include <asm/linkage.h>
 
+#define KSP_WORD_OFF 	((TASK_THREAD + THREAD_KSP) / 4)
+
 ;################### Low Level Context Switch ##########################
 
 	.section .sched.text,"ax",@progbits
@@ -28,8 +30,13 @@ __switch_to:
 	SAVE_CALLEE_SAVED_KERNEL
 
 	/* Save the now KSP in task->thread.ksp */
-	st.as  sp, [r0, (TASK_THREAD + THREAD_KSP)/4]
-
+#if KSP_WORD_OFF  <= 255
+	st.as  sp, [r0, KSP_WORD_OFF]
+#else
+	/* Workaround for NR_CPUS=4k as ST.as can only take s9 offset */
+	add2	r24, r0, KSP_WORD_OFF
+	st	sp, [r24]
+#endif
 	/*
 	* Return last task in r0 (return reg)
 	* On ARC, Return reg = First Arg reg = r0.
diff --git a/arch/arc/kernel/devtree.c b/arch/arc/kernel/devtree.c
index 2340af0e1d6..b6dc4e21fd3 100644
--- a/arch/arc/kernel/devtree.c
+++ b/arch/arc/kernel/devtree.c
@@ -14,10 +14,22 @@
 #include <linux/memblock.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
-#include <asm/prom.h>
 #include <asm/clk.h>
 #include <asm/mach_desc.h>
 
+static const void * __init arch_get_next_mach(const char *const **match)
+{
+	static const struct machine_desc *mdesc = __arch_info_begin;
+	const struct machine_desc *m = mdesc;
+
+	if (m >= __arch_info_end)
+		return NULL;
+
+	mdesc++;
+	*match = m->dt_compat;
+	return m;
+}
+
 /**
  * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
  * @dt:		virtual address pointer to dt blob
@@ -25,93 +37,24 @@
  * If a dtb was passed to the kernel, then use it to choose the correct
  * machine_desc and to setup the system.
  */
-struct machine_desc * __init setup_machine_fdt(void *dt)
+const struct machine_desc * __init setup_machine_fdt(void *dt)
 {
-	struct boot_param_header *devtree = dt;
-	struct machine_desc *mdesc = NULL, *mdesc_best = NULL;
-	unsigned int score, mdesc_score = ~1;
+	const struct machine_desc *mdesc;
 	unsigned long dt_root;
-	const char *model, *compat;
 	void *clk;
-	char manufacturer[16];
 	unsigned long len;
 
-	/* check device tree validity */
-	if (be32_to_cpu(devtree->magic) != OF_DT_HEADER)
+	if (!early_init_dt_scan(dt))
 		return NULL;
 
-	initial_boot_params = devtree;
-	dt_root = of_get_flat_dt_root();
-
-	/*
-	 * The kernel could be multi-platform enabled, thus could have many
-	 * "baked-in" machine descriptors. Search thru all for the best
-	 * "compatible" string match.
-	 */
-	for_each_machine_desc(mdesc) {
-		score = of_flat_dt_match(dt_root, mdesc->dt_compat);
-		if (score > 0 && score < mdesc_score) {
-			mdesc_best = mdesc;
-			mdesc_score = score;
-		}
-	}
-	if (!mdesc_best) {
-		const char *prop;
-		long size;
-
-		pr_err("\n unrecognized device tree list:\n[ ");
-
-		prop = of_get_flat_dt_prop(dt_root, "compatible", &size);
-		if (prop) {
-			while (size > 0) {
-				printk("'%s' ", prop);
-				size -= strlen(prop) + 1;
-				prop += strlen(prop) + 1;
-			}
-		}
-		printk("]\n\n");
-
+	mdesc = of_flat_dt_match_machine(NULL, arch_get_next_mach);
+	if (!mdesc)
 		machine_halt();
-	}
-
-	/* compat = "<manufacturer>,<model>" */
-	compat =  mdesc_best->dt_compat[0];
-
-	model = strchr(compat, ',');
-	if (model)
-		model++;
-
-	strlcpy(manufacturer, compat, model ? model - compat : strlen(compat));
-
-	pr_info("Board \"%s\" from %s (Manufacturer)\n", model, manufacturer);
-
-	/* Retrieve various information from the /chosen node */
-	of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
-
-	/* Initialize {size,address}-cells info */
-	of_scan_flat_dt(early_init_dt_scan_root, NULL);
-
-	/* Setup memory, calling early_init_dt_add_memory_arch */
-	of_scan_flat_dt(early_init_dt_scan_memory, NULL);
 
+	dt_root = of_get_flat_dt_root();
 	clk = of_get_flat_dt_prop(dt_root, "clock-frequency", &len);
 	if (clk)
 		arc_set_core_freq(of_read_ulong(clk, len/4));
 
-	return mdesc_best;
-}
-
-/*
- * Copy the flattened DT out of .init since unflattening doesn't copy strings
- * and the normal DT APIs refs them from orig flat DT
- */
-void __init copy_devtree(void)
-{
-	void *alloc = early_init_dt_alloc_memory_arch(
-			be32_to_cpu(initial_boot_params->totalsize), 64);
-	if (alloc) {
-		memcpy(alloc, initial_boot_params,
-				be32_to_cpu(initial_boot_params->totalsize));
-		initial_boot_params = alloc;
-	}
+	return mdesc;
 }
diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index b908dde8a33..47d09d07f09 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -250,6 +250,14 @@ ARC_ENTRY handle_interrupt_level1
 	lr  r0, [icause1]
 	and r0, r0, 0x1f
 
+#ifdef CONFIG_TRACE_IRQFLAGS
+	; icause1 needs to be read early, before calling tracing, which
+	; can clobber scratch regs, hence use of stack to stash it
+	push r0
+	TRACE_ASM_IRQ_DISABLE
+	pop  r0
+#endif
+
 	bl.d  @arch_do_IRQ
 	mov r1, sp
 
@@ -337,9 +345,9 @@ ARC_ENTRY EV_TLBProtV
 	;  vineetg: Mar 6th: Random Seg Fault issue #1
 	;  ecr and efa were not saved in case an Intr sneaks in
 	;  after fake rtie
-	;
+
 	lr  r2, [ecr]
-	lr  r1, [efa]	; Faulting Data address
+	lr  r0, [efa]	; Faulting Data address
 
 	; --------(4) Return from CPU Exception Mode ---------
 	;  Fake a rtie, but rtie to next label
@@ -348,6 +356,8 @@ ARC_ENTRY EV_TLBProtV
 
 	FAKE_RET_FROM_EXCPN r9
 
+	mov   r1, sp
+
 	;------ (5) Type of Protection Violation? ----------
 	;
 	; ProtV Hardware Exception is triggered for Access Faults of 2 types
@@ -358,16 +368,12 @@ ARC_ENTRY EV_TLBProtV
 	bbit1 r2, ECR_C_BIT_PROTV_MISALIG_DATA, 4f
 
 	;========= (6a) Access Violation Processing ========
-	mov r0, sp              ; pt_regs
 	bl  do_page_fault
 	b   ret_from_exception
 
 	;========== (6b) Non aligned access ============
 4:
-	mov r0, r1
-	mov r1, sp              ; pt_regs
 
-#ifdef  CONFIG_ARC_MISALIGN_ACCESS
 	SAVE_CALLEE_SAVED_USER
 	mov r2, sp              ; callee_regs
 
@@ -376,9 +382,6 @@ ARC_ENTRY EV_TLBProtV
 	; TBD: optimize - do this only if a callee reg was involved
 	; either a dst of emulated LD/ST or src with address-writeback
 	RESTORE_CALLEE_SAVED_USER
-#else
-	bl  do_misaligned_error
-#endif
 
 	b   ret_from_exception
 
@@ -575,6 +578,7 @@ resume_user_mode_begin:
 	; --- (Slow Path #2) pending signal  ---
 	mov r0, sp	; pt_regs for arg to do_signal()/do_notify_resume()
 
+	GET_CURR_THR_INFO_FLAGS   r9
 	bbit0  r9, TIF_SIGPENDING, .Lchk_notify_resume
 
 	; Normal Trap/IRQ entry only saves Scratch (caller-saved) regs
@@ -640,6 +644,8 @@ resume_kernel_mode:
 
 restore_regs :
 
+	TRACE_ASM_IRQ_ENABLE
+
 	lr	r10, [status32]
 
 	; Restore REG File. In case multiple Events outstanding,
diff --git a/arch/arc/kernel/head.S b/arch/arc/kernel/head.S
index 0f944f02451..2c878e964a6 100644
--- a/arch/arc/kernel/head.S
+++ b/arch/arc/kernel/head.S
@@ -95,7 +95,7 @@ stext:
 ;----------------------------------------------------------------
 ;     First lines of code run by secondary before jumping to 'C'
 ;----------------------------------------------------------------
-	.section .init.text, "ax",@progbits
+	.section .text, "ax",@progbits
 	.type first_lines_of_secondary, @function
 	.globl first_lines_of_secondary
 
diff --git a/arch/arc/kernel/irq.c b/arch/arc/kernel/irq.c
index 5fc92455da3..a4b141ee9a6 100644
--- a/arch/arc/kernel/irq.c
+++ b/arch/arc/kernel/irq.c
@@ -39,10 +39,14 @@ void arc_init_IRQ(void)
 	level_mask |= IS_ENABLED(CONFIG_ARC_IRQ5_LV2) << 5;
 	level_mask |= IS_ENABLED(CONFIG_ARC_IRQ6_LV2) << 6;
 
-	if (level_mask) {
+	/*
+	 * Write to register, even if no LV2 IRQs configured to reset it
+	 * in case bootloader had mucked with it
+	 */
+	write_aux_reg(AUX_IRQ_LEV, level_mask);
+
+	if (level_mask)
 		pr_info("Level-2 interrupts bitset %x\n", level_mask);
-		write_aux_reg(AUX_IRQ_LEV, level_mask);
-	}
 }
 
 /*
@@ -146,7 +150,7 @@ void arch_do_IRQ(unsigned int irq, struct pt_regs *regs)
 	set_irq_regs(old_regs);
 }
 
-int __init get_hw_config_num_irq(void)
+int get_hw_config_num_irq(void)
 {
 	uint32_t val = read_aux_reg(ARC_REG_VECBASE_BCR);
 
diff --git a/arch/arc/kernel/kgdb.c b/arch/arc/kernel/kgdb.c
index a7698fb1481..a2ff5c5d145 100644
--- a/arch/arc/kernel/kgdb.c
+++ b/arch/arc/kernel/kgdb.c
@@ -196,6 +196,18 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
 	instruction_pointer(regs) = ip;
 }
 
+static void kgdb_call_nmi_hook(void *ignored)
+{
+	kgdb_nmicallback(raw_smp_processor_id(), NULL);
+}
+
+void kgdb_roundup_cpus(unsigned long flags)
+{
+	local_irq_enable();
+	smp_call_function(kgdb_call_nmi_hook, NULL, 0);
+	local_irq_disable();
+}
+
 struct kgdb_arch arch_kgdb_ops = {
 	/* breakpoint instruction: TRAP_S 0x3 */
 #ifdef CONFIG_CPU_BIG_ENDIAN
diff --git a/arch/arc/kernel/kprobes.c b/arch/arc/kernel/kprobes.c
index 72f97822784..42b05046fad 100644
--- a/arch/arc/kernel/kprobes.c
+++ b/arch/arc/kernel/kprobes.c
@@ -87,13 +87,13 @@ static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
 
 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 {
-	__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+	__this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
 	kcb->kprobe_status = kcb->prev_kprobe.status;
 }
 
 static inline void __kprobes set_current_kprobe(struct kprobe *p)
 {
-	__get_cpu_var(current_kprobe) = p;
+	__this_cpu_write(current_kprobe, p);
 }
 
 static void __kprobes resume_execution(struct kprobe *p, unsigned long addr,
@@ -237,7 +237,7 @@ int __kprobes arc_kprobe_handler(unsigned long addr, struct pt_regs *regs)
 
 		return 1;
 	} else if (kprobe_running()) {
-		p = __get_cpu_var(current_kprobe);
+		p = __this_cpu_read(current_kprobe);
 		if (p->break_handler && p->break_handler(p, regs)) {
 			setup_singlestep(p, regs);
 			kcb->kprobe_status = KPROBE_HIT_SS;
@@ -327,7 +327,7 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned long trapnr)
 		 */
 
 		/* We increment the nmissed count for accounting,
-		 * we can also use npre/npostfault count for accouting
+		 * we can also use npre/npostfault count for accounting
 		 * these specific fault cases.
 		 */
 		kprobes_inc_nmissed_count(cur);
diff --git a/arch/arc/kernel/ptrace.c b/arch/arc/kernel/ptrace.c
index 333238564b6..5d76706139d 100644
--- a/arch/arc/kernel/ptrace.c
+++ b/arch/arc/kernel/ptrace.c
@@ -102,7 +102,7 @@ static int genregs_set(struct task_struct *target,
 	REG_IGNORE_ONE(pad2);
 	REG_IN_CHUNK(callee, efa, cregs);	/* callee_regs[r25..r13] */
 	REG_IGNORE_ONE(efa);			/* efa update invalid */
-	REG_IN_ONE(stop_pc, &ptregs->ret);	/* stop_pc: PC update */
+	REG_IGNORE_ONE(stop_pc);			/* PC updated via @ret */
 
 	return ret;
 }
diff --git a/arch/arc/kernel/reset.c b/arch/arc/kernel/reset.c
index e227a2b1c94..2768fa1e39b 100644
--- a/arch/arc/kernel/reset.c
+++ b/arch/arc/kernel/reset.c
@@ -31,3 +31,4 @@ void machine_power_off(void)
 }
 
 void (*pm_power_off) (void) = NULL;
+EXPORT_SYMBOL(pm_power_off);
diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index 2c68bc7e6a7..643eae4436e 100644
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -21,7 +21,6 @@
 #include <asm/setup.h>
 #include <asm/page.h>
 #include <asm/irq.h>
-#include <asm/prom.h>
 #include <asm/unwind.h>
 #include <asm/clk.h>
 #include <asm/mach_desc.h>
@@ -31,14 +30,13 @@
 int running_on_hw = 1;	/* vs. on ISS */
 
 char __initdata command_line[COMMAND_LINE_SIZE];
-struct machine_desc *machine_desc;
+const struct machine_desc *machine_desc;
 
 struct task_struct *_current_task[NR_CPUS];	/* For stack switching */
 
 struct cpuinfo_arc cpuinfo_arc700[NR_CPUS];
 
-
-void read_arc_build_cfg_regs(void)
+static void read_arc_build_cfg_regs(void)
 {
 	struct bcr_perip uncached_space;
 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()];
@@ -106,7 +104,7 @@ static const struct cpuinfo_data arc_cpu_tbl[] = {
 	{ {0x00, NULL		} }
 };
 
-char *arc_cpu_mumbojumbo(int cpu_id, char *buf, int len)
+static char *arc_cpu_mumbojumbo(int cpu_id, char *buf, int len)
 {
 	int n = 0;
 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[cpu_id];
@@ -171,7 +169,7 @@ static const struct id_to_str mac_mul_nm[] = {
 	{0x6, "Dual 16x16 and 32x16"}
 };
 
-char *arc_extn_mumbojumbo(int cpu_id, char *buf, int len)
+static char *arc_extn_mumbojumbo(int cpu_id, char *buf, int len)
 {
 	int n = 0;
 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[cpu_id];
@@ -234,7 +232,7 @@ char *arc_extn_mumbojumbo(int cpu_id, char *buf, int len)
 	return buf;
 }
 
-void arc_chk_ccms(void)
+static void arc_chk_ccms(void)
 {
 #if defined(CONFIG_ARC_HAS_DCCM) || defined(CONFIG_ARC_HAS_ICCM)
 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()];
@@ -269,7 +267,7 @@ void arc_chk_ccms(void)
  * hardware has dedicated regs which need to be saved/restored on ctx-sw
  * (Single Precision uses core regs), thus kernel is kind of oblivious to it
  */
-void arc_chk_fpu(void)
+static void arc_chk_fpu(void)
 {
 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()];
 
@@ -346,8 +344,7 @@ void __init setup_arch(char **cmdline_p)
 	setup_arch_memory();
 
 	/* copy flat DT out of .init and then unflatten it */
-	copy_devtree();
-	unflatten_device_tree();
+	unflatten_and_copy_device_tree();
 
 	/* Can be issue if someone passes cmd line arg "ro"
 	 * But that is unlikely so keeping it as it is
diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c
index ee6ef2f60a2..7e95e1a8651 100644
--- a/arch/arc/kernel/signal.c
+++ b/arch/arc/kernel/signal.c
@@ -101,7 +101,6 @@ SYSCALL_DEFINE0(rt_sigreturn)
 {
 	struct rt_sigframe __user *sf;
 	unsigned int magic;
-	int err;
 	struct pt_regs *regs = current_pt_regs();
 
 	/* Always make any pending restarted system calls return -EINTR */
@@ -119,15 +118,16 @@ SYSCALL_DEFINE0(rt_sigreturn)
 	if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
 		goto badframe;
 
-	err = restore_usr_regs(regs, sf);
-	err |= __get_user(magic, &sf->sigret_magic);
-	if (err)
+	if (__get_user(magic, &sf->sigret_magic))
 		goto badframe;
 
 	if (unlikely(is_do_ss_needed(magic)))
 		if (restore_altstack(&sf->uc.uc_stack))
 			goto badframe;
 
+	if (restore_usr_regs(regs, sf))
+		goto badframe;
+
 	/* Don't restart from sigreturn */
 	syscall_wont_restart(regs);
 
@@ -191,6 +191,15 @@ setup_rt_frame(int signo, struct k_sigaction *ka, siginfo_t *info,
 		return 1;
 
 	/*
+	 * w/o SA_SIGINFO, struct ucontext is partially populated (only
+	 * uc_mcontext/uc_sigmask) for kernel's normal user state preservation
+	 * during signal handler execution. This works for SA_SIGINFO as well
+	 * although the semantics are now overloaded (the same reg state can be
+	 * inspected by userland: but are they allowed to fiddle with it ?
+	 */
+	err |= stash_usr_regs(sf, regs, set);
+
+	/*
 	 * SA_SIGINFO requires 3 args to signal handler:
 	 *  #1: sig-no (common to any handler)
 	 *  #2: struct siginfo
@@ -213,14 +222,6 @@ setup_rt_frame(int signo, struct k_sigaction *ka, siginfo_t *info,
 		magic = MAGIC_SIGALTSTK;
 	}
 
-	/*
-	 * w/o SA_SIGINFO, struct ucontext is partially populated (only
-	 * uc_mcontext/uc_sigmask) for kernel's normal user state preservation
-	 * during signal handler execution. This works for SA_SIGINFO as well
-	 * although the semantics are now overloaded (the same reg state can be
-	 * inspected by userland: but are they allowed to fiddle with it ?
-	 */
-	err |= stash_usr_regs(sf, regs, set);
 	err |= __put_user(magic, &sf->sigret_magic);
 	if (err)
 		return err;
diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c
index bca3052c956..c2f9ebbc38f 100644
--- a/arch/arc/kernel/smp.c
+++ b/arch/arc/kernel/smp.c
@@ -95,7 +95,7 @@ void __init smp_cpus_done(unsigned int max_cpus)
  *        If it turns out to be elaborate, it's better to code it in assembly
  *
  */
-void __attribute__((weak)) arc_platform_smp_wait_to_boot(int cpu)
+void __weak arc_platform_smp_wait_to_boot(int cpu)
 {
 	/*
 	 * As a hack for debugging - since debugger will single-step over the
@@ -128,6 +128,7 @@ void start_kernel_secondary(void)
 	atomic_inc(&mm->mm_users);
 	atomic_inc(&mm->mm_count);
 	current->active_mm = mm;
+	cpumask_set_cpu(cpu, mm_cpumask(mm));
 
 	notify_cpu_starting(cpu);
 	set_cpu_online(cpu, true);
@@ -210,7 +211,6 @@ enum ipi_msg_type {
 	IPI_NOP = 0,
 	IPI_RESCHEDULE = 1,
 	IPI_CALL_FUNC,
-	IPI_CALL_FUNC_SINGLE,
 	IPI_CPU_STOP
 };
 
@@ -254,7 +254,7 @@ void smp_send_stop(void)
 
 void arch_send_call_function_single_ipi(int cpu)
 {
-	ipi_send_msg(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
+	ipi_send_msg(cpumask_of(cpu), IPI_CALL_FUNC);
 }
 
 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
@@ -286,10 +286,6 @@ static inline void __do_IPI(unsigned long *ops, struct ipi_data *ipi, int cpu)
 			generic_smp_call_function_interrupt();
 			break;
 
-		case IPI_CALL_FUNC_SINGLE:
-			generic_smp_call_function_single_interrupt();
-			break;
-
 		case IPI_CPU_STOP:
 			ipi_cpu_stop(cpu);
 			break;
diff --git a/arch/arc/kernel/stacktrace.c b/arch/arc/kernel/stacktrace.c
index f8b7d880304..9ce47cfe230 100644
--- a/arch/arc/kernel/stacktrace.c
+++ b/arch/arc/kernel/stacktrace.c
@@ -237,11 +237,14 @@ unsigned int get_wchan(struct task_struct *tsk)
  */
 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 {
+	/* Assumes @tsk is sleeping so unwinds from __switch_to */
 	arc_unwind_core(tsk, NULL, __collect_all_but_sched, trace);
 }
 
 void save_stack_trace(struct stack_trace *trace)
 {
-	arc_unwind_core(current, NULL, __collect_all, trace);
+	/* Pass NULL for task so it unwinds the current call frame */
+	arc_unwind_core(NULL, NULL, __collect_all, trace);
 }
+EXPORT_SYMBOL_GPL(save_stack_trace);
 #endif
diff --git a/arch/arc/kernel/time.c b/arch/arc/kernel/time.c
index 0e51e69cf30..e5f3a837fb3 100644
--- a/arch/arc/kernel/time.c
+++ b/arch/arc/kernel/time.c
@@ -63,9 +63,10 @@
 
 int arc_counter_setup(void)
 {
-	/* RTSC insn taps into cpu clk, needs no setup */
-
-	/* For SMP, only allowed if cross-core-sync, hence usable as cs */
+	/*
+	 * For SMP this needs to be 0. However Kconfig glue doesn't
+	 * enable this option for SMP configs
+	 */
 	return 1;
 }
 
@@ -206,7 +207,7 @@ static DEFINE_PER_CPU(struct clock_event_device, arc_clockevent_device) = {
 
 static irqreturn_t timer_irq_handler(int irq, void *dev_id)
 {
-	struct clock_event_device *clk = &__get_cpu_var(arc_clockevent_device);
+	struct clock_event_device *clk = this_cpu_ptr(&arc_clockevent_device);
 
 	arc_timer_event_ack(clk->mode == CLOCK_EVT_MODE_PERIODIC);
 	clk->event_handler(clk);
@@ -223,16 +224,13 @@ static struct irqaction arc_timer_irq = {
  * Setup the local event timer for @cpu
  * N.B. weak so that some exotic ARC SoCs can completely override it
  */
-void __attribute__((weak)) arc_local_timer_setup(unsigned int cpu)
+void __weak arc_local_timer_setup(unsigned int cpu)
 {
 	struct clock_event_device *clk = &per_cpu(arc_clockevent_device, cpu);
 
-	clockevents_calc_mult_shift(clk, arc_get_core_freq(), 5);
-
-	clk->max_delta_ns = clockevent_delta2ns(ARC_TIMER_MAX, clk);
 	clk->cpumask = cpumask_of(cpu);
-
-	clockevents_register_device(clk);
+	clockevents_config_and_register(clk, arc_get_core_freq(),
+					0, ARC_TIMER_MAX);
 
 	/*
 	 * setup the per-cpu timer IRQ handler - for all cpus
diff --git a/arch/arc/kernel/traps.c b/arch/arc/kernel/traps.c
index e21692d2fda..3eadfdabc32 100644
--- a/arch/arc/kernel/traps.c
+++ b/arch/arc/kernel/traps.c
@@ -84,19 +84,18 @@ DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", do_memory_error, BUS_ADRERR)
 DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
 DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)
 
-#ifdef CONFIG_ARC_MISALIGN_ACCESS
 /*
  * Entry Point for Misaligned Data access Exception, for emulating in software
  */
 int do_misaligned_access(unsigned long address, struct pt_regs *regs,
 			 struct callee_regs *cregs)
 {
+	/* If emulation not enabled, or failed, kill the task */
 	if (misaligned_fixup(address, regs, cregs) != 0)
 		return do_misaligned_error(address, regs);
 
 	return 0;
 }
-#endif
 
 /*
  * Entry point for miscll errors such as Nested Exceptions
diff --git a/arch/arc/kernel/unaligned.c b/arch/arc/kernel/unaligned.c
index 28d17006074..7ff5b5c183b 100644
--- a/arch/arc/kernel/unaligned.c
+++ b/arch/arc/kernel/unaligned.c
@@ -245,6 +245,12 @@ int misaligned_fixup(unsigned long address, struct pt_regs *regs,
 		regs->status32 &= ~STATUS_DE_MASK;
 	} else {
 		regs->ret += state.instr_len;
+
+		/* handle zero-overhead-loop */
+		if ((regs->ret == regs->lp_end) && (regs->lp_count)) {
+			regs->ret = regs->lp_start;
+			regs->lp_count--;
+		}
 	}
 
 	return 0;