Merge tag 'csky-for-linus-5.9-rc1' of https://github.com/c-sky/csky-linux

Pull arch/csky updates from Guo Ren:
 "New features:
   - seccomp-filter
   - err-injection
   - top-down&random mmap-layout
   - irq_work
   - show_ipi
   - context-tracking

  Fixes & Optimizations:
   - kprobe_on_ftrace
   - optimize panic print"

* tag 'csky-for-linus-5.9-rc1' of https://github.com/c-sky/csky-linux:
  csky: Add context tracking support
  csky: Add arch_show_interrupts for IPI interrupts
  csky: Add irq_work support
  csky: Fixup warning by EXPORT_SYMBOL(kmap)
  csky: Set CONFIG_NR_CPU 4 as default
  csky: Use top-down mmap layout
  csky: Optimize the trap processing flow
  csky: Add support for function error injection
  csky: Fixup kprobes handler couldn't change pc
  csky: Fixup duplicated restore sp in RESTORE_REGS_FTRACE
  csky: Add cpu feature register hint for smp
  csky: Add SECCOMP_FILTER supported
  csky: remove unusued thread_saved_pc and *_segments functions/macros

18 files changed, 307 insertions, 142 deletions

diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 902f1142d550..3d5afb5f5685 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -9,6 +9,7 @@ config CSKY
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_QUEUED_RWLOCKS if NR_CPUS>2
 	select ARCH_WANT_FRAME_POINTERS if !CPU_CK610
+	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
 	select COMMON_CLK
 	select CLKSRC_MMIO
 	select CSKY_MPINTC if CPU_CK860
@@ -38,11 +39,16 @@ config CSKY
 	select GX6605S_TIMER if CPU_CK610
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_AUDITSYSCALL
+	select HAVE_ARCH_MMAP_RND_BITS
+	select HAVE_ARCH_SECCOMP_FILTER
+	select HAVE_CONTEXT_TRACKING
+	select HAVE_VIRT_CPU_ACCOUNTING_GEN
 	select HAVE_DEBUG_BUGVERBOSE
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUNCTION_GRAPH_TRACER
+	select HAVE_FUNCTION_ERROR_INJECTION
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_KERNEL_GZIP
 	select HAVE_KERNEL_LZO
@@ -148,6 +154,14 @@ config L1_CACHE_SHIFT
 	default "5"	if (CPU_CK807 || CPU_CK810)
 	default "6"	if (CPU_CK860)
 
+config ARCH_MMAP_RND_BITS_MIN
+	default 8
+
+# max bits determined by the following formula:
+#  VA_BITS - PAGE_SHIFT - 3
+config ARCH_MMAP_RND_BITS_MAX
+	default 17
+
 menu "Processor type and features"
 
 choice
@@ -266,7 +280,7 @@ config NR_CPUS
 	int "Maximum number of CPUs (2-32)"
 	range 2 32
 	depends on SMP
-	default "2"
+	default "4"
 
 config HIGHMEM
 	bool "High Memory Support"
@@ -295,3 +309,16 @@ endmenu
 source "arch/csky/Kconfig.platforms"
 
 source "kernel/Kconfig.hz"
+
+config SECCOMP
+	bool "Enable seccomp to safely compute untrusted bytecode"
+	help
+	  This kernel feature is useful for number crunching applications
+	  that may need to compute untrusted bytecode during their
+	  execution. By using pipes or other transports made available to
+	  the process as file descriptors supporting the read/write
+	  syscalls, it's possible to isolate those applications in
+	  their own address space using seccomp. Once seccomp is
+	  enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
+	  and the task is only allowed to execute a few safe syscalls
+	  defined by each seccomp mode.
diff --git a/arch/csky/abiv2/inc/abi/entry.h b/arch/csky/abiv2/inc/abi/entry.h
index 4fdd6c12e7ff..bedcc6f06bba 100644
--- a/arch/csky/abiv2/inc/abi/entry.h
+++ b/arch/csky/abiv2/inc/abi/entry.h
@@ -136,8 +136,6 @@
 
 .macro	RESTORE_REGS_FTRACE
 	ldw	tls, (sp, 0)
-	ldw	a0, (sp, 16)
-	mtcr	a0, ss0
 
 #ifdef CONFIG_CPU_HAS_HILO
 	ldw	a0, (sp, 140)
@@ -158,7 +156,6 @@
 	addi    sp, 40
 	ldm     r16-r30, (sp)
 	addi    sp, 72
-	mfcr	sp, ss0
 .endm
 
 .macro SAVE_SWITCH_STACK
diff --git a/arch/csky/abiv2/mcount.S b/arch/csky/abiv2/mcount.S
index 911512bf480f..d745e10c10b0 100644
--- a/arch/csky/abiv2/mcount.S
+++ b/arch/csky/abiv2/mcount.S
@@ -55,7 +55,9 @@
 
 .macro mcount_exit_regs
 	RESTORE_REGS_FTRACE
-	ldw	t1, (sp, 0)
+	subi	sp, 152
+	ldw	t1, (sp, 4)
+	addi	sp, 152
 	ldw	r8, (sp, 4)
 	ldw	lr, (sp, 8)
 	addi	sp, 12
diff --git a/arch/csky/include/asm/Kbuild b/arch/csky/include/asm/Kbuild
index 93372255984d..64876e59e2ef 100644
--- a/arch/csky/include/asm/Kbuild
+++ b/arch/csky/include/asm/Kbuild
@@ -4,5 +4,6 @@ generic-y += gpio.h
 generic-y += kvm_para.h
 generic-y += local64.h
 generic-y += qrwlock.h
+generic-y += seccomp.h
 generic-y += user.h
 generic-y += vmlinux.lds.h
diff --git a/arch/csky/include/asm/bug.h b/arch/csky/include/asm/bug.h
index bd7b3235bb84..33ebd16b9c78 100644
--- a/arch/csky/include/asm/bug.h
+++ b/arch/csky/include/asm/bug.h
@@ -20,7 +20,8 @@ do {					\
 
 struct pt_regs;
 
-void die_if_kernel(char *str, struct pt_regs *regs, int nr);
+void die(struct pt_regs *regs, const char *str);
 void show_regs(struct pt_regs *regs);
+void show_code(struct pt_regs *regs);
 
 #endif /* __ASM_CSKY_BUG_H */
diff --git a/arch/csky/include/asm/irq_work.h b/arch/csky/include/asm/irq_work.h
new file mode 100644
index 000000000000..33aaf39d6f94
--- /dev/null
+++ b/arch/csky/include/asm/irq_work.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_CSKY_IRQ_WORK_H
+#define __ASM_CSKY_IRQ_WORK_H
+
+static inline bool arch_irq_work_has_interrupt(void)
+{
+	return true;
+}
+extern void arch_irq_work_raise(void);
+#endif /* __ASM_CSKY_IRQ_WORK_H */
diff --git a/arch/csky/include/asm/processor.h b/arch/csky/include/asm/processor.h
index 24442d8e86f9..4800f6563abb 100644
--- a/arch/csky/include/asm/processor.h
+++ b/arch/csky/include/asm/processor.h
@@ -82,12 +82,6 @@ static inline void release_thread(struct task_struct *dead_task)
 
 extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 
-#define copy_segments(tsk, mm)		do { } while (0)
-#define release_segments(mm)		do { } while (0)
-#define forget_segments()		do { } while (0)
-
-extern unsigned long thread_saved_pc(struct task_struct *tsk);
-
 unsigned long get_wchan(struct task_struct *p);
 
 #define KSTK_EIP(tsk)		(task_pt_regs(tsk)->pc)
diff --git a/arch/csky/include/asm/ptrace.h b/arch/csky/include/asm/ptrace.h
index bcfb7070e48d..91ceb1b454c9 100644
--- a/arch/csky/include/asm/ptrace.h
+++ b/arch/csky/include/asm/ptrace.h
@@ -24,6 +24,7 @@
 #define user_mode(regs) (!((regs)->sr & PS_S))
 #define instruction_pointer(regs) ((regs)->pc)
 #define profile_pc(regs) instruction_pointer(regs)
+#define trap_no(regs) ((regs->sr >> 16) & 0xff)
 
 static inline void instruction_pointer_set(struct pt_regs *regs,
 					   unsigned long val)
@@ -52,6 +53,12 @@ static inline unsigned long regs_return_value(struct pt_regs *regs)
 	return regs->a0;
 }
 
+static inline void regs_set_return_value(struct pt_regs *regs,
+					 unsigned long val)
+{
+	regs->a0 = val;
+}
+
 /* Valid only for Kernel mode traps. */
 static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
 {
diff --git a/arch/csky/include/asm/thread_info.h b/arch/csky/include/asm/thread_info.h
index 8980e4e64391..68e7a1227170 100644
--- a/arch/csky/include/asm/thread_info.h
+++ b/arch/csky/include/asm/thread_info.h
@@ -85,6 +85,6 @@ static inline struct thread_info *current_thread_info(void)
 				 _TIF_NOTIFY_RESUME | _TIF_UPROBE)
 
 #define _TIF_SYSCALL_WORK	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
-				 _TIF_SYSCALL_TRACEPOINT)
+				 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP)
 
 #endif	/* _ASM_CSKY_THREAD_INFO_H */
diff --git a/arch/csky/kernel/entry.S b/arch/csky/kernel/entry.S
index f13800383a19..5a5cabd076e1 100644
--- a/arch/csky/kernel/entry.S
+++ b/arch/csky/kernel/entry.S
@@ -23,6 +23,24 @@
 #endif
 .endm
 
+.macro	context_tracking
+#ifdef CONFIG_CONTEXT_TRACKING
+	mfcr	a0, epsr
+	btsti	a0, 31
+	bt	1f
+	jbsr	context_tracking_user_exit
+	ldw	a0, (sp, LSAVE_A0)
+	ldw	a1, (sp, LSAVE_A1)
+	ldw	a2, (sp, LSAVE_A2)
+	ldw	a3, (sp, LSAVE_A3)
+#if defined(__CSKYABIV1__)
+	ldw	r6, (sp, LSAVE_A4)
+	ldw	r7, (sp, LSAVE_A5)
+#endif
+1:
+#endif
+.endm
+
 .macro tlbop_begin name, val0, val1, val2
 ENTRY(csky_\name)
 	mtcr    a3, ss2
@@ -103,6 +121,7 @@ ENTRY(csky_\name)
 .endm
 .macro tlbop_end is_write
 	zero_fp
+	context_tracking
 	RD_MEH	a2
 	psrset  ee, ie
 	mov     a0, sp
@@ -128,6 +147,7 @@ tlbop_end 1
 ENTRY(csky_systemcall)
 	SAVE_ALL TRAP0_SIZE
 	zero_fp
+	context_tracking
 	psrset  ee, ie
 
 	lrw     r9, __NR_syscalls
@@ -168,6 +188,8 @@ ENTRY(csky_systemcall)
 csky_syscall_trace:
 	mov	a0, sp                  /* sp = pt_regs pointer */
 	jbsr	syscall_trace_enter
+	cmpnei	a0, 0
+	bt	1f
 	/* Prepare args before do system call */
 	ldw	a0, (sp, LSAVE_A0)
 	ldw	a1, (sp, LSAVE_A1)
@@ -188,6 +210,7 @@ csky_syscall_trace:
 #endif
 	stw	a0, (sp, LSAVE_A0)	/* Save return value */
 
+1:
 #ifdef CONFIG_DEBUG_RSEQ
 	mov	a0, sp
 	jbsr	rseq_syscall
@@ -234,6 +257,9 @@ ret_from_exception:
 	and	r10, r9
 	cmpnei	r10, 0
 	bt	exit_work
+#ifdef CONFIG_CONTEXT_TRACKING
+	jbsr	context_tracking_user_enter
+#endif
 1:
 #ifdef CONFIG_PREEMPTION
 	mov	r9, sp
@@ -274,6 +300,7 @@ work_resched:
 ENTRY(csky_trap)
 	SAVE_ALL 0
 	zero_fp
+	context_tracking
 	psrset	ee
 	mov	a0, sp                 /* Push Stack pointer arg */
 	jbsr	trap_c                 /* Call C-level trap handler */
@@ -308,6 +335,7 @@ ENTRY(csky_get_tls)
 ENTRY(csky_irq)
 	SAVE_ALL 0
 	zero_fp
+	context_tracking
 	psrset	ee
 
 #ifdef CONFIG_TRACE_IRQFLAGS
diff --git a/arch/csky/kernel/process.c b/arch/csky/kernel/process.c
index 28cfeaaf902a..f730869e21ee 100644
--- a/arch/csky/kernel/process.c
+++ b/arch/csky/kernel/process.c
@@ -30,16 +30,6 @@ asmlinkage void ret_from_kernel_thread(void);
  */
 void flush_thread(void){}
 
-/*
- * Return saved PC from a blocked thread
- */
-unsigned long thread_saved_pc(struct task_struct *tsk)
-{
-	struct switch_stack *sw = (struct switch_stack *)tsk->thread.sp;
-
-	return sw->r15;
-}
-
 int copy_thread(unsigned long clone_flags,
 		unsigned long usp,
 		unsigned long kthread_arg,
diff --git a/arch/csky/kernel/ptrace.c b/arch/csky/kernel/ptrace.c
index 944ca2fdcdd9..b06612c408c4 100644
--- a/arch/csky/kernel/ptrace.c
+++ b/arch/csky/kernel/ptrace.c
@@ -320,16 +320,20 @@ long arch_ptrace(struct task_struct *child, long request,
 	return ret;
 }
 
-asmlinkage void syscall_trace_enter(struct pt_regs *regs)
+asmlinkage int syscall_trace_enter(struct pt_regs *regs)
 {
 	if (test_thread_flag(TIF_SYSCALL_TRACE))
 		if (tracehook_report_syscall_entry(regs))
-			syscall_set_nr(current, regs, -1);
+			return -1;
+
+	if (secure_computing() == -1)
+		return -1;
 
 	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
 		trace_sys_enter(regs, syscall_get_nr(current, regs));
 
 	audit_syscall_entry(regs_syscallid(regs), regs->a0, regs->a1, regs->a2, regs->a3);
+	return 0;
 }
 
 asmlinkage void syscall_trace_exit(struct pt_regs *regs)
@@ -343,13 +347,8 @@ asmlinkage void syscall_trace_exit(struct pt_regs *regs)
 		trace_sys_exit(regs, syscall_get_return_value(current, regs));
 }
 
-extern void show_stack(struct task_struct *task, unsigned long *stack, const char *loglvl);
 void show_regs(struct pt_regs *fp)
 {
-	unsigned long   *sp;
-	unsigned char   *tp;
-	int	i;
-
 	pr_info("\nCURRENT PROCESS:\n\n");
 	pr_info("COMM=%s PID=%d\n", current->comm, current->pid);
 
@@ -396,29 +395,9 @@ void show_regs(struct pt_regs *fp)
 		fp->regs[0], fp->regs[1], fp->regs[2], fp->regs[3]);
 	pr_info("r10: 0x%08lx  r11: 0x%08lx  r12: 0x%08lx  r13: 0x%08lx\n",
 		fp->regs[4], fp->regs[5], fp->regs[6], fp->regs[7]);
-	pr_info("r14: 0x%08lx   r1: 0x%08lx  r15: 0x%08lx\n",
-		fp->regs[8], fp->regs[9], fp->lr);
+	pr_info("r14: 0x%08lx   r1: 0x%08lx\n",
+		fp->regs[8], fp->regs[9]);
 #endif
 
-	pr_info("\nCODE:");
-	tp = ((unsigned char *) fp->pc) - 0x20;
-	tp += ((int)tp % 4) ? 2 : 0;
-	for (sp = (unsigned long *) tp, i = 0; (i < 0x40);  i += 4) {
-		if ((i % 0x10) == 0)
-			pr_cont("\n%08x: ", (int) (tp + i));
-		pr_cont("%08x ", (int) *sp++);
-	}
-	pr_cont("\n");
-
-	pr_info("\nKERNEL STACK:");
-	tp = ((unsigned char *) fp) - 0x40;
-	for (sp = (unsigned long *) tp, i = 0; (i < 0xc0); i += 4) {
-		if ((i % 0x10) == 0)
-			pr_cont("\n%08x: ", (int) (tp + i));
-		pr_cont("%08x ", (int) *sp++);
-	}
-	pr_cont("\n");
-
-	show_stack(NULL, (unsigned long *)fp->regs[4], KERN_INFO);
 	return;
 }
diff --git a/arch/csky/kernel/smp.c b/arch/csky/kernel/smp.c
index b5c5bc3afeb5..e7425e6b0419 100644
--- a/arch/csky/kernel/smp.c
+++ b/arch/csky/kernel/smp.c
@@ -12,8 +12,10 @@
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/irq.h>
+#include <linux/irq_work.h>
 #include <linux/irqdomain.h>
 #include <linux/of.h>
+#include <linux/seq_file.h>
 #include <linux/sched/task_stack.h>
 #include <linux/sched/mm.h>
 #include <linux/sched/hotplug.h>
@@ -26,20 +28,24 @@
 #include <abi/fpu.h>
 #endif
 
-struct ipi_data_struct {
-	unsigned long bits ____cacheline_aligned;
-};
-static DEFINE_PER_CPU(struct ipi_data_struct, ipi_data);
-
 enum ipi_message_type {
 	IPI_EMPTY,
 	IPI_RESCHEDULE,
 	IPI_CALL_FUNC,
+	IPI_IRQ_WORK,
 	IPI_MAX
 };
 
+struct ipi_data_struct {
+	unsigned long bits ____cacheline_aligned;
+	unsigned long stats[IPI_MAX] ____cacheline_aligned;
+};
+static DEFINE_PER_CPU(struct ipi_data_struct, ipi_data);
+
 static irqreturn_t handle_ipi(int irq, void *dev)
 {
+	unsigned long *stats = this_cpu_ptr(&ipi_data)->stats;
+
 	while (true) {
 		unsigned long ops;
 
@@ -47,11 +53,20 @@ static irqreturn_t handle_ipi(int irq, void *dev)
 		if (ops == 0)
 			return IRQ_HANDLED;
 
-		if (ops & (1 << IPI_RESCHEDULE))
+		if (ops & (1 << IPI_RESCHEDULE)) {
+			stats[IPI_RESCHEDULE]++;
 			scheduler_ipi();
+		}
 
-		if (ops & (1 << IPI_CALL_FUNC))
+		if (ops & (1 << IPI_CALL_FUNC)) {
+			stats[IPI_CALL_FUNC]++;
 			generic_smp_call_function_interrupt();
+		}
+
+		if (ops & (1 << IPI_IRQ_WORK)) {
+			stats[IPI_IRQ_WORK]++;
+			irq_work_run();
+		}
 
 		BUG_ON((ops >> IPI_MAX) != 0);
 	}
@@ -83,6 +98,29 @@ send_ipi_message(const struct cpumask *to_whom, enum ipi_message_type operation)
 	send_arch_ipi(to_whom);
 }
 
+static const char * const ipi_names[] = {
+	[IPI_EMPTY]		= "Empty interrupts",
+	[IPI_RESCHEDULE]	= "Rescheduling interrupts",
+	[IPI_CALL_FUNC]		= "Function call interrupts",
+	[IPI_IRQ_WORK]		= "Irq work interrupts",
+};
+
+int arch_show_interrupts(struct seq_file *p, int prec)
+{
+	unsigned int cpu, i;
+
+	for (i = 0; i < IPI_MAX; i++) {
+		seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
+			   prec >= 4 ? " " : "");
+		for_each_online_cpu(cpu)
+			seq_printf(p, "%10lu ",
+				per_cpu_ptr(&ipi_data, cpu)->stats[i]);
+		seq_printf(p, " %s\n", ipi_names[i]);
+	}
+
+	return 0;
+}
+
 void arch_send_call_function_ipi_mask(struct cpumask *mask)
 {
 	send_ipi_message(mask, IPI_CALL_FUNC);
@@ -108,6 +146,13 @@ void smp_send_reschedule(int cpu)
 	send_ipi_message(cpumask_of(cpu), IPI_RESCHEDULE);
 }
 
+#ifdef CONFIG_IRQ_WORK
+void arch_irq_work_raise(void)
+{
+	send_ipi_message(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
+}
+#endif
+
 void __init smp_prepare_boot_cpu(void)
 {
 }
@@ -156,6 +201,7 @@ void __init setup_smp(void)
 extern void _start_smp_secondary(void);
 
 volatile unsigned int secondary_hint;
+volatile unsigned int secondary_hint2;
 volatile unsigned int secondary_ccr;
 volatile unsigned int secondary_stack;
 
@@ -168,6 +214,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 	secondary_stack =
 		(unsigned int) task_stack_page(tidle) + THREAD_SIZE - 8;
 	secondary_hint = mfcr("cr31");
+	secondary_hint2 = mfcr("cr<21, 1>");
 	secondary_ccr  = mfcr("cr18");
 	secondary_msa1 = read_mmu_msa1();
 
@@ -209,6 +256,7 @@ void csky_start_secondary(void)
 	unsigned int cpu = smp_processor_id();
 
 	mtcr("cr31", secondary_hint);
+	mtcr("cr<21, 1>", secondary_hint2);
 	mtcr("cr18", secondary_ccr);
 
 	mtcr("vbr", vec_base);
diff --git a/arch/csky/kernel/traps.c b/arch/csky/kernel/traps.c
index fcc3a69831ad..959a917c989d 100644
--- a/arch/csky/kernel/traps.c
+++ b/arch/csky/kernel/traps.c
@@ -15,6 +15,8 @@
 #include <linux/rtc.h>
 #include <linux/uaccess.h>
 #include <linux/kprobes.h>
+#include <linux/kdebug.h>
+#include <linux/sched/debug.h>
 
 #include <asm/setup.h>
 #include <asm/traps.h>
@@ -27,6 +29,8 @@
 #include <abi/fpu.h>
 #endif
 
+int show_unhandled_signals = 1;
+
 /* Defined in entry.S */
 asmlinkage void csky_trap(void);
 
@@ -77,117 +81,184 @@ void __init trap_init(void)
 #endif
 }
 
-void die_if_kernel(char *str, struct pt_regs *regs, int nr)
+static DEFINE_SPINLOCK(die_lock);
+
+void die(struct pt_regs *regs, const char *str)
 {
-	if (user_mode(regs))
-		return;
+	static int die_counter;
+	int ret;
 
+	oops_enter();
+
+	spin_lock_irq(&die_lock);
 	console_verbose();
-	pr_err("%s: %08x\n", str, nr);
+	bust_spinlocks(1);
+
+	pr_emerg("%s [#%d]\n", str, ++die_counter);
+	print_modules();
 	show_regs(regs);
+	show_stack(current, (unsigned long *)regs->regs[4], KERN_INFO);
+
+	ret = notify_die(DIE_OOPS, str, regs, 0, trap_no(regs), SIGSEGV);
+
+	bust_spinlocks(0);
 	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
-	do_exit(SIGSEGV);
+	spin_unlock_irq(&die_lock);
+	oops_exit();
+
+	if (in_interrupt())
+		panic("Fatal exception in interrupt");
+	if (panic_on_oops)
+		panic("Fatal exception");
+	if (ret != NOTIFY_STOP)
+		do_exit(SIGSEGV);
 }
 
-void buserr(struct pt_regs *regs)
+void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr)
 {
-#ifdef CONFIG_CPU_CK810
-	static unsigned long prev_pc;
+	struct task_struct *tsk = current;
 
-	if ((regs->pc == prev_pc) && prev_pc != 0) {
-		prev_pc = 0;
-	} else {
-		prev_pc = regs->pc;
-		return;
+	if (show_unhandled_signals && unhandled_signal(tsk, signo)
+	    && printk_ratelimit()) {
+		pr_info("%s[%d]: unhandled signal %d code 0x%x at 0x%08lx",
+			tsk->comm, task_pid_nr(tsk), signo, code, addr);
+		print_vma_addr(KERN_CONT " in ", instruction_pointer(regs));
+		pr_cont("\n");
+		show_regs(regs);
 	}
-#endif
 
-	die_if_kernel("Kernel mode BUS error", regs, 0);
+	force_sig_fault(signo, code, (void __user *)addr);
+}
 
-	pr_err("User mode Bus Error\n");
-	show_regs(regs);
+static void do_trap_error(struct pt_regs *regs, int signo, int code,
+	unsigned long addr, const char *str)
+{
+	current->thread.trap_no = trap_no(regs);
 
-	force_sig_fault(SIGSEGV, 0, (void __user *)regs->pc);
+	if (user_mode(regs)) {
+		do_trap(regs, signo, code, addr);
+	} else {
+		if (!fixup_exception(regs))
+			die(regs, str);
+	}
 }
 
-asmlinkage void trap_c(struct pt_regs *regs)
-{
-	int sig;
-	unsigned long vector;
-	siginfo_t info;
-	struct task_struct *tsk = current;
+#define DO_ERROR_INFO(name, signo, code, str)				\
+asmlinkage __visible void name(struct pt_regs *regs)			\
+{									\
+	do_trap_error(regs, signo, code, regs->pc, "Oops - " str);	\
+}
 
-	vector = (regs->sr >> 16) & 0xff;
+DO_ERROR_INFO(do_trap_unknown,
+	SIGILL, ILL_ILLTRP, "unknown exception");
+DO_ERROR_INFO(do_trap_zdiv,
+	SIGFPE, FPE_INTDIV, "error zero div exception");
+DO_ERROR_INFO(do_trap_buserr,
+	SIGSEGV, ILL_ILLADR, "error bus error exception");
 
-	switch (vector) {
-	case VEC_ZERODIV:
-		die_if_kernel("Kernel mode ZERO DIV", regs, vector);
-		sig = SIGFPE;
-		break;
-	/* ptrace */
-	case VEC_TRACE:
+asmlinkage void do_trap_misaligned(struct pt_regs *regs)
+{
+#ifdef CONFIG_CPU_NEED_SOFTALIGN
+	csky_alignment(regs);
+#else
+	current->thread.trap_no = trap_no(regs);
+	do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->pc,
+		      "Oops - load/store address misaligned");
+#endif
+}
+
+asmlinkage void do_trap_bkpt(struct pt_regs *regs)
+{
 #ifdef CONFIG_KPROBES
-		if (kprobe_single_step_handler(regs))
-			return;
+	if (kprobe_single_step_handler(regs))
+		return;
 #endif
 #ifdef CONFIG_UPROBES
-		if (uprobe_single_step_handler(regs))
-			return;
+	if (uprobe_single_step_handler(regs))
+		return;
 #endif
-		info.si_code = TRAP_TRACE;
-		sig = SIGTRAP;
-		break;
-	case VEC_ILLEGAL:
-		tsk->thread.trap_no = vector;
+	if (user_mode(regs)) {
+		send_sig(SIGTRAP, current, 0);
+		return;
+	}
+
+	do_trap_error(regs, SIGILL, ILL_ILLTRP, regs->pc,
+		      "Oops - illegal trap exception");
+}
+
+asmlinkage void do_trap_illinsn(struct pt_regs *regs)
+{
+	current->thread.trap_no = trap_no(regs);
+
 #ifdef CONFIG_KPROBES
-		if (kprobe_breakpoint_handler(regs))
-			return;
+	if (kprobe_breakpoint_handler(regs))
+		return;
 #endif
 #ifdef CONFIG_UPROBES
-		if (uprobe_breakpoint_handler(regs))
-			return;
+	if (uprobe_breakpoint_handler(regs))
+		return;
 #endif
-		die_if_kernel("Kernel mode ILLEGAL", regs, vector);
 #ifndef CONFIG_CPU_NO_USER_BKPT
-		if (*(uint16_t *)instruction_pointer(regs) != USR_BKPT)
+	if (*(uint16_t *)instruction_pointer(regs) != USR_BKPT) {
+		send_sig(SIGTRAP, current, 0);
+		return;
+	}
 #endif
-		{
-			sig = SIGILL;
-			break;
-		}
-	/* gdbserver  breakpoint */
+
+	do_trap_error(regs, SIGILL, ILL_ILLOPC, regs->pc,
+		      "Oops - illegal instruction exception");
+}
+
+asmlinkage void do_trap_fpe(struct pt_regs *regs)
+{
+#ifdef CONFIG_CPU_HAS_FP
+	return fpu_fpe(regs);
+#else
+	do_trap_error(regs, SIGILL, ILL_ILLOPC, regs->pc,
+		      "Oops - fpu instruction exception");
+#endif
+}
+
+asmlinkage void do_trap_priv(struct pt_regs *regs)
+{
+#ifdef CONFIG_CPU_HAS_FP
+	if (user_mode(regs) && fpu_libc_helper(regs))
+		return;
+#endif
+	do_trap_error(regs, SIGILL, ILL_PRVOPC, regs->pc,
+		      "Oops - illegal privileged exception");
+}
+
+asmlinkage void trap_c(struct pt_regs *regs)
+{
+	switch (trap_no(regs)) {
+	case VEC_ZERODIV:
+		do_trap_zdiv(regs);
+		break;
+	case VEC_TRACE:
+		do_trap_bkpt(regs);
+		break;
+	case VEC_ILLEGAL:
+		do_trap_illinsn(regs);
+		break;
 	case VEC_TRAP1:
-	/* jtagserver breakpoint */
 	case VEC_BREAKPOINT:
-		die_if_kernel("Kernel mode BKPT", regs, vector);
-		info.si_code = TRAP_BRKPT;
-		sig = SIGTRAP;
+		do_trap_bkpt(regs);
 		break;
 	case VEC_ACCESS:
-		tsk->thread.trap_no = vector;
-		return buserr(regs);
-#ifdef CONFIG_CPU_NEED_SOFTALIGN
+		do_trap_buserr(regs);
+		break;
 	case VEC_ALIGN:
-		tsk->thread.trap_no = vector;
-		return csky_alignment(regs);
-#endif
-#ifdef CONFIG_CPU_HAS_FPU
+		do_trap_misaligned(regs);
+		break;
 	case VEC_FPE:
-		tsk->thread.trap_no = vector;
-		die_if_kernel("Kernel mode FPE", regs, vector);
-		return fpu_fpe(regs);
+		do_trap_fpe(regs);
+		break;
 	case VEC_PRIV:
-		tsk->thread.trap_no = vector;
-		die_if_kernel("Kernel mode PRIV", regs, vector);
-		if (fpu_libc_helper(regs))
-			return;
-#endif
+		do_trap_priv(regs);
+		break;
 	default:
-		sig = SIGSEGV;
+		do_trap_unknown(regs);
 		break;
 	}
-
-	tsk->thread.trap_no = vector;
-
-	send_sig(sig, current, 0);
 }
diff --git a/arch/csky/lib/Makefile b/arch/csky/lib/Makefile
index 078e2d5f32e1..7fbdbb2c4d12 100644
--- a/arch/csky/lib/Makefile
+++ b/arch/csky/lib/Makefile
@@ -1,2 +1,3 @@
 # SPDX-License-Identifier: GPL-2.0-only
 lib-y  := usercopy.o delay.o
+obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o
diff --git a/arch/csky/lib/error-inject.c b/arch/csky/lib/error-inject.c
new file mode 100644
index 000000000000..c15fb36fe067
--- /dev/null
+++ b/arch/csky/lib/error-inject.c
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/error-injection.h>
+#include <linux/kprobes.h>
+
+void override_function_with_return(struct pt_regs *regs)
+{
+	instruction_pointer_set(regs, regs->lr);
+}
+NOKPROBE_SYMBOL(override_function_with_return);
diff --git a/arch/csky/mm/fault.c b/arch/csky/mm/fault.c
index 0b9cbf2cf6a9..b1dce9f2f04d 100644
--- a/arch/csky/mm/fault.c
+++ b/arch/csky/mm/fault.c
@@ -183,13 +183,13 @@ bad_area:
 bad_area_nosemaphore:
 	/* User mode accesses just cause a SIGSEGV */
 	if (user_mode(regs)) {
-		tsk->thread.trap_no = (regs->sr >> 16) & 0xff;
+		tsk->thread.trap_no = trap_no(regs);
 		force_sig_fault(SIGSEGV, si_code, (void __user *)address);
 		return;
 	}
 
 no_context:
-	tsk->thread.trap_no = (regs->sr >> 16) & 0xff;
+	tsk->thread.trap_no = trap_no(regs);
 
 	/* Are we prepared to handle this kernel fault? */
 	if (fixup_exception(regs))
@@ -202,10 +202,10 @@ no_context:
 	bust_spinlocks(1);
 	pr_alert("Unable to handle kernel paging request at virtual "
 		 "address 0x%08lx, pc: 0x%08lx\n", address, regs->pc);
-	die_if_kernel("Oops", regs, write);
+	die(regs, "Oops");
 
 out_of_memory:
-	tsk->thread.trap_no = (regs->sr >> 16) & 0xff;
+	tsk->thread.trap_no = trap_no(regs);
 
 	/*
 	 * We ran out of memory, call the OOM killer, and return the userspace
@@ -215,7 +215,7 @@ out_of_memory:
 	return;
 
 do_sigbus:
-	tsk->thread.trap_no = (regs->sr >> 16) & 0xff;
+	tsk->thread.trap_no = trap_no(regs);
 
 	mmap_read_unlock(mm);
 
diff --git a/arch/csky/mm/highmem.c b/arch/csky/mm/highmem.c
index 89ec32e602a1..89c10800a002 100644
--- a/arch/csky/mm/highmem.c
+++ b/arch/csky/mm/highmem.c
@@ -19,8 +19,6 @@ void kmap_flush_tlb(unsigned long addr)
 }
 EXPORT_SYMBOL(kmap_flush_tlb);
 
-EXPORT_SYMBOL(kmap);
-
 void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
 {
 	unsigned long vaddr;