/*

   * Main exception handling logic.
   *
   * Copyright 2004-2010 Analog Devices Inc.

   *

   * Licensed under the GPL-2 or later

   */

  #include <linux/bug.h>

  #include <linux/uaccess.h>

  #include <linux/module.h>

  #include <asm/traps.h>

  #include <asm/cplb.h>

  #include <asm/blackfin.h>

  #include <asm/irq_handler.h>

  #include <linux/irq.h>

  #include <asm/trace.h>

  #include <asm/fixed_code.h>

  #include <asm/pseudo_instructions.h>

  
  #ifdef CONFIG_KGDB

  # include <linux/kgdb.h>

  
  # define CHK_DEBUGGER_TRAP() \
  	do { \

  		kgdb_handle_exception(trapnr, sig, info.si_code, fp); \

  	} while (0)
  # define CHK_DEBUGGER_TRAP_MAYBE() \
  	do { \
  		if (kgdb_connected) \
  			CHK_DEBUGGER_TRAP(); \
  	} while (0)
  #else
  # define CHK_DEBUGGER_TRAP() do { } while (0)
  # define CHK_DEBUGGER_TRAP_MAYBE() do { } while (0)

  #endif

  #ifdef CONFIG_DEBUG_VERBOSE

  #define verbose_printk(fmt, arg...) \
  	printk(fmt, ##arg)
  #else
  #define verbose_printk(fmt, arg...) \
  	({ if (0) printk(fmt, ##arg); 0; })
  #endif

  #if defined(CONFIG_DEBUG_MMRS) || defined(CONFIG_DEBUG_MMRS_MODULE)
  u32 last_seqstat;
  #ifdef CONFIG_DEBUG_MMRS_MODULE
  EXPORT_SYMBOL(last_seqstat);
  #endif
  #endif

  /* Initiate the event table handler */
  void __init trap_init(void)
  {
  	CSYNC();
  	bfin_write_EVT3(trap);
  	CSYNC();
  }

  static int kernel_mode_regs(struct pt_regs *regs)
  {
  	return regs->ipend & 0xffc0;
  }

  asmlinkage notrace void trap_c(struct pt_regs *fp)

  {

  #ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
  	int j;
  #endif

  #ifdef CONFIG_BFIN_PSEUDODBG_INSNS
  	int opcode;
  #endif

  	unsigned int cpu = raw_smp_processor_id();

  	const char *strerror = NULL;

  	int sig = 0;

  	siginfo_t info;
  	unsigned long trapnr = fp->seqstat & SEQSTAT_EXCAUSE;

  	trace_buffer_save(j);

  #if defined(CONFIG_DEBUG_MMRS) || defined(CONFIG_DEBUG_MMRS_MODULE)
  	last_seqstat = (u32)fp->seqstat;
  #endif

  
  	/* Important - be very careful dereferncing pointers - will lead to
  	 * double faults if the stack has become corrupt
  	 */

  	/* trap_c() will be called for exceptions. During exceptions
  	 * processing, the pc value should be set with retx value.
  	 * With this change we can cleanup some code in signal.c- TODO
  	 */
  	fp->orig_pc = fp->retx;
  	/* printk("exception: 0x%x, ipend=%x, reti=%x, retx=%x
  ",
  		trapnr, fp->ipend, fp->pc, fp->retx); */
  
  	/* send the appropriate signal to the user program */
  	switch (trapnr) {

  	/* This table works in conjunction with the one in ./mach-common/entry.S

  	 * Some exceptions are handled there (in assembly, in exception space)
  	 * Some are handled here, (in C, in interrupt space)
  	 * Some, like CPLB, are handled in both, where the normal path is
  	 * handled in assembly/exception space, and the error path is handled
  	 * here
  	 */
  
  	/* 0x00 - Linux Syscall, getting here is an error */
  	/* 0x01 - userspace gdb breakpoint, handled here */
  	case VEC_EXCPT01:
  		info.si_code = TRAP_ILLTRAP;
  		sig = SIGTRAP;
  		CHK_DEBUGGER_TRAP_MAYBE();
  		/* Check if this is a breakpoint in kernel space */

  		if (kernel_mode_regs(fp))

  			goto traps_done;

  		else
  			break;

  	/* 0x03 - User Defined, userspace stack overflow */

  	case VEC_EXCPT03:
  		info.si_code = SEGV_STACKFLOW;
  		sig = SIGSEGV;

  		strerror = KERN_NOTICE EXC_0x03(KERN_NOTICE);

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;

  	/* 0x02 - KGDB initial connection and break signal trap */
  	case VEC_EXCPT02:
  #ifdef CONFIG_KGDB
  		info.si_code = TRAP_ILLTRAP;
  		sig = SIGTRAP;
  		CHK_DEBUGGER_TRAP();

  		goto traps_done;

  #endif

  	/* 0x04 - User Defined */
  	/* 0x05 - User Defined */
  	/* 0x06 - User Defined */
  	/* 0x07 - User Defined */
  	/* 0x08 - User Defined */
  	/* 0x09 - User Defined */
  	/* 0x0A - User Defined */
  	/* 0x0B - User Defined */
  	/* 0x0C - User Defined */
  	/* 0x0D - User Defined */
  	/* 0x0E - User Defined */
  	/* 0x0F - User Defined */

  	/* If we got here, it is most likely that someone was trying to use a

  	 * custom exception handler, and it is not actually installed properly
  	 */
  	case VEC_EXCPT04 ... VEC_EXCPT15:
  		info.si_code = ILL_ILLPARAOP;
  		sig = SIGILL;

  		strerror = KERN_NOTICE EXC_0x04(KERN_NOTICE);

  		CHK_DEBUGGER_TRAP_MAYBE();
  		break;

  	/* 0x10 HW Single step, handled here */
  	case VEC_STEP:
  		info.si_code = TRAP_STEP;
  		sig = SIGTRAP;
  		CHK_DEBUGGER_TRAP_MAYBE();
  		/* Check if this is a single step in kernel space */

  		if (kernel_mode_regs(fp))

  			goto traps_done;

  		else
  			break;
  	/* 0x11 - Trace Buffer Full, handled here */
  	case VEC_OVFLOW:
  		info.si_code = TRAP_TRACEFLOW;
  		sig = SIGTRAP;

  		strerror = KERN_NOTICE EXC_0x11(KERN_NOTICE);

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;
  	/* 0x12 - Reserved, Caught by default */
  	/* 0x13 - Reserved, Caught by default */
  	/* 0x14 - Reserved, Caught by default */
  	/* 0x15 - Reserved, Caught by default */
  	/* 0x16 - Reserved, Caught by default */
  	/* 0x17 - Reserved, Caught by default */
  	/* 0x18 - Reserved, Caught by default */
  	/* 0x19 - Reserved, Caught by default */
  	/* 0x1A - Reserved, Caught by default */
  	/* 0x1B - Reserved, Caught by default */
  	/* 0x1C - Reserved, Caught by default */
  	/* 0x1D - Reserved, Caught by default */
  	/* 0x1E - Reserved, Caught by default */
  	/* 0x1F - Reserved, Caught by default */
  	/* 0x20 - Reserved, Caught by default */
  	/* 0x21 - Undefined Instruction, handled here */
  	case VEC_UNDEF_I:

  #ifdef CONFIG_BUG
  		if (kernel_mode_regs(fp)) {
  			switch (report_bug(fp->pc, fp)) {
  			case BUG_TRAP_TYPE_NONE:
  				break;
  			case BUG_TRAP_TYPE_WARN:
  				dump_bfin_trace_buffer();
  				fp->pc += 2;
  				goto traps_done;
  			case BUG_TRAP_TYPE_BUG:
  				/* call to panic() will dump trace, and it is
  				 * off at this point, so it won't be clobbered
  				 */
  				panic("BUG()");
  			}
  		}
  #endif

  #ifdef CONFIG_BFIN_PSEUDODBG_INSNS
  		/*
  		 * Support for the fake instructions, if the instruction fails,
  		 * then just execute a illegal opcode failure (like normal).
  		 * Don't support these instructions inside the kernel
  		 */
  		if (!kernel_mode_regs(fp) && get_instruction(&opcode, (unsigned short *)fp->pc)) {
  			if (execute_pseudodbg_assert(fp, opcode))
  				goto traps_done;

  			if (execute_pseudodbg(fp, opcode))
  				goto traps_done;

  		}
  #endif

  		info.si_code = ILL_ILLOPC;
  		sig = SIGILL;

  		strerror = KERN_NOTICE EXC_0x21(KERN_NOTICE);

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;
  	/* 0x22 - Illegal Instruction Combination, handled here */
  	case VEC_ILGAL_I:
  		info.si_code = ILL_ILLPARAOP;
  		sig = SIGILL;

  		strerror = KERN_NOTICE EXC_0x22(KERN_NOTICE);

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;

  	/* 0x23 - Data CPLB protection violation, handled here */

  	case VEC_CPLB_VL:
  		info.si_code = ILL_CPLB_VI;

  		sig = SIGSEGV;

  		strerror = KERN_NOTICE EXC_0x23(KERN_NOTICE);

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;
  	/* 0x24 - Data access misaligned, handled here */
  	case VEC_MISALI_D:
  		info.si_code = BUS_ADRALN;
  		sig = SIGBUS;

  		strerror = KERN_NOTICE EXC_0x24(KERN_NOTICE);

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;
  	/* 0x25 - Unrecoverable Event, handled here */
  	case VEC_UNCOV:
  		info.si_code = ILL_ILLEXCPT;
  		sig = SIGILL;

  		strerror = KERN_NOTICE EXC_0x25(KERN_NOTICE);

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;
  	/* 0x26 - Data CPLB Miss, normal case is handled in _cplb_hdr,
  		error case is handled here */
  	case VEC_CPLB_M:
  		info.si_code = BUS_ADRALN;
  		sig = SIGBUS;

  		strerror = KERN_NOTICE EXC_0x26(KERN_NOTICE);

  		break;
  	/* 0x27 - Data CPLB Multiple Hits - Linux Trap Zero, handled here */
  	case VEC_CPLB_MHIT:
  		info.si_code = ILL_CPLB_MULHIT;

  		sig = SIGSEGV;

  #ifdef CONFIG_DEBUG_HUNT_FOR_ZERO

  		if (cpu_pda[cpu].dcplb_fault_addr < FIXED_CODE_START)

  			strerror = KERN_NOTICE "NULL pointer access
  ";

  		else

  #endif

  			strerror = KERN_NOTICE EXC_0x27(KERN_NOTICE);

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;
  	/* 0x28 - Emulation Watchpoint, handled here */
  	case VEC_WATCH:
  		info.si_code = TRAP_WATCHPT;
  		sig = SIGTRAP;

  		pr_debug(EXC_0x28(KERN_DEBUG));

  		CHK_DEBUGGER_TRAP_MAYBE();
  		/* Check if this is a watchpoint in kernel space */

  		if (kernel_mode_regs(fp))

  			goto traps_done;

  		else
  			break;
  #ifdef CONFIG_BF535
  	/* 0x29 - Instruction fetch access error (535 only) */
  	case VEC_ISTRU_VL:      /* ADSP-BF535 only (MH) */
  		info.si_code = BUS_OPFETCH;
  		sig = SIGBUS;

  		strerror = KERN_NOTICE "BF535: VEC_ISTRU_VL
  ";

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;
  #else
  	/* 0x29 - Reserved, Caught by default */
  #endif
  	/* 0x2A - Instruction fetch misaligned, handled here */
  	case VEC_MISALI_I:
  		info.si_code = BUS_ADRALN;
  		sig = SIGBUS;

  		strerror = KERN_NOTICE EXC_0x2A(KERN_NOTICE);

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;

  	/* 0x2B - Instruction CPLB protection violation, handled here */

  	case VEC_CPLB_I_VL:
  		info.si_code = ILL_CPLB_VI;

  		sig = SIGBUS;

  		strerror = KERN_NOTICE EXC_0x2B(KERN_NOTICE);

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;
  	/* 0x2C - Instruction CPLB miss, handled in _cplb_hdr */
  	case VEC_CPLB_I_M:
  		info.si_code = ILL_CPLB_MISS;
  		sig = SIGBUS;

  		strerror = KERN_NOTICE EXC_0x2C(KERN_NOTICE);

  		break;
  	/* 0x2D - Instruction CPLB Multiple Hits, handled here */
  	case VEC_CPLB_I_MHIT:
  		info.si_code = ILL_CPLB_MULHIT;

  		sig = SIGSEGV;

  #ifdef CONFIG_DEBUG_HUNT_FOR_ZERO

  		if (cpu_pda[cpu].icplb_fault_addr < FIXED_CODE_START)

  			strerror = KERN_NOTICE "Jump to NULL address
  ";

  		else

  #endif

  			strerror = KERN_NOTICE EXC_0x2D(KERN_NOTICE);

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;
  	/* 0x2E - Illegal use of Supervisor Resource, handled here */
  	case VEC_ILL_RES:
  		info.si_code = ILL_PRVOPC;
  		sig = SIGILL;

  		strerror = KERN_NOTICE EXC_0x2E(KERN_NOTICE);

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;
  	/* 0x2F - Reserved, Caught by default */
  	/* 0x30 - Reserved, Caught by default */
  	/* 0x31 - Reserved, Caught by default */
  	/* 0x32 - Reserved, Caught by default */
  	/* 0x33 - Reserved, Caught by default */
  	/* 0x34 - Reserved, Caught by default */
  	/* 0x35 - Reserved, Caught by default */
  	/* 0x36 - Reserved, Caught by default */
  	/* 0x37 - Reserved, Caught by default */
  	/* 0x38 - Reserved, Caught by default */
  	/* 0x39 - Reserved, Caught by default */
  	/* 0x3A - Reserved, Caught by default */
  	/* 0x3B - Reserved, Caught by default */
  	/* 0x3C - Reserved, Caught by default */
  	/* 0x3D - Reserved, Caught by default */
  	/* 0x3E - Reserved, Caught by default */
  	/* 0x3F - Reserved, Caught by default */

  	case VEC_HWERR:
  		info.si_code = BUS_ADRALN;
  		sig = SIGBUS;
  		switch (fp->seqstat & SEQSTAT_HWERRCAUSE) {
  		/* System MMR Error */
  		case (SEQSTAT_HWERRCAUSE_SYSTEM_MMR):
  			info.si_code = BUS_ADRALN;
  			sig = SIGBUS;

  			strerror = KERN_NOTICE HWC_x2(KERN_NOTICE);

  			break;
  		/* External Memory Addressing Error */
  		case (SEQSTAT_HWERRCAUSE_EXTERN_ADDR):

  			if (ANOMALY_05000310) {
  				static unsigned long anomaly_rets;
  
  				if ((fp->pc >= (L1_CODE_START + L1_CODE_LENGTH - 512)) &&
  				    (fp->pc < (L1_CODE_START + L1_CODE_LENGTH))) {
  					/*
  					 * A false hardware error will happen while fetching at
  					 * the L1 instruction SRAM boundary.  Ignore it.
  					 */
  					anomaly_rets = fp->rets;
  					goto traps_done;
  				} else if (fp->rets == anomaly_rets) {
  					/*
  					 * While boundary code returns to a function, at the ret
  					 * point, a new false hardware error might occur too based
  					 * on tests.  Ignore it too.
  					 */
  					goto traps_done;
  				} else if ((fp->rets >= (L1_CODE_START + L1_CODE_LENGTH - 512)) &&
  				           (fp->rets < (L1_CODE_START + L1_CODE_LENGTH))) {
  					/*
  					 * If boundary code calls a function, at the entry point,
  					 * a new false hardware error maybe happen based on tests.
  					 * Ignore it too.
  					 */
  					goto traps_done;
  				} else
  					anomaly_rets = 0;
  			}

  			info.si_code = BUS_ADRERR;
  			sig = SIGBUS;

  			strerror = KERN_NOTICE HWC_x3(KERN_NOTICE);

  			break;
  		/* Performance Monitor Overflow */
  		case (SEQSTAT_HWERRCAUSE_PERF_FLOW):

  			strerror = KERN_NOTICE HWC_x12(KERN_NOTICE);

  			break;
  		/* RAISE 5 instruction */
  		case (SEQSTAT_HWERRCAUSE_RAISE_5):
  			printk(KERN_NOTICE HWC_x18(KERN_NOTICE));
  			break;
  		default:        /* Reserved */
  			printk(KERN_NOTICE HWC_default(KERN_NOTICE));
  			break;
  		}

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;

  	/*
  	 * We should be handling all known exception types above,
  	 * if we get here we hit a reserved one, so panic
  	 */

  	default:

  		info.si_code = ILL_ILLPARAOP;
  		sig = SIGILL;

  		verbose_printk(KERN_EMERG "Caught Unhandled Exception, code = %08lx
  ",

  			(fp->seqstat & SEQSTAT_EXCAUSE));

  		CHK_DEBUGGER_TRAP_MAYBE();

  		break;
  	}

  	BUG_ON(sig == 0);

  	/* If the fault was caused by a kernel thread, or interrupt handler
  	 * we will kernel panic, so the system reboots.
  	 */
  	if (kernel_mode_regs(fp) || (current && !current->mm)) {
  		console_verbose();
  		oops_in_progress = 1;

  	}

  	if (sig != SIGTRAP) {

  		if (strerror)
  			verbose_printk(strerror);

  		dump_bfin_process(fp);

  		dump_bfin_mem(fp);

  		show_regs(fp);

  
  		/* Print out the trace buffer if it makes sense */
  #ifndef CONFIG_DEBUG_BFIN_NO_KERN_HWTRACE
  		if (trapnr == VEC_CPLB_I_M || trapnr == VEC_CPLB_M)

  			verbose_printk(KERN_NOTICE "No trace since you do not have "

  			       "CONFIG_DEBUG_BFIN_NO_KERN_HWTRACE enabled
  
  ");

  		else
  #endif
  			dump_bfin_trace_buffer();

  		if (oops_in_progress) {

  			/* Dump the current kernel stack */

  			verbose_printk(KERN_NOTICE "Kernel Stack
  ");

  			show_stack(current, NULL);

  			print_modules();

  #ifndef CONFIG_ACCESS_CHECK

  			verbose_printk(KERN_EMERG "Please turn on "

  			       "CONFIG_ACCESS_CHECK
  ");

  #endif

  			panic("Kernel exception");

  		} else {

  #ifdef CONFIG_DEBUG_VERBOSE

  			unsigned long *stack;

  			/* Dump the user space stack */
  			stack = (unsigned long *)rdusp();

  			verbose_printk(KERN_NOTICE "Userspace Stack
  ");

  			show_stack(NULL, stack);

  #endif

  		}

  	}

  #ifdef CONFIG_IPIPE
  	if (!ipipe_trap_notify(fp->seqstat & 0x3f, fp))
  #endif
  	{
  		info.si_signo = sig;
  		info.si_errno = 0;

  		switch (trapnr) {
  		case VEC_CPLB_VL:
  		case VEC_MISALI_D:
  		case VEC_CPLB_M:
  		case VEC_CPLB_MHIT:
  			info.si_addr = (void __user *)cpu_pda[cpu].dcplb_fault_addr;
  			break;
  		default:
  			info.si_addr = (void __user *)fp->pc;
  			break;
  		}

  		force_sig_info(sig, &info, current);
  	}

  	if ((ANOMALY_05000461 && trapnr == VEC_HWERR && !access_ok(VERIFY_READ, fp->pc, 8)) ||

  	    (ANOMALY_05000281 && trapnr == VEC_HWERR) ||
  	    (ANOMALY_05000189 && (trapnr == VEC_CPLB_I_VL || trapnr == VEC_CPLB_VL)))

  		fp->pc = SAFE_USER_INSTRUCTION;

   traps_done:

  	trace_buffer_restore(j);

  }

  asmlinkage void double_fault_c(struct pt_regs *fp)

  {

  #ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON

  	int j;
  	trace_buffer_save(j);

  #endif

  	console_verbose();
  	oops_in_progress = 1;

  #ifdef CONFIG_DEBUG_VERBOSE

  	printk(KERN_EMERG "Double Fault
  ");
  #ifdef CONFIG_DEBUG_DOUBLEFAULT_PRINT
  	if (((long)fp->seqstat &  SEQSTAT_EXCAUSE) == VEC_UNCOV) {
  		unsigned int cpu = raw_smp_processor_id();
  		char buf[150];
  		decode_address(buf, cpu_pda[cpu].retx_doublefault);
  		printk(KERN_EMERG "While handling exception (EXCAUSE = 0x%x) at %s:
  ",
  			(unsigned int)cpu_pda[cpu].seqstat_doublefault & SEQSTAT_EXCAUSE, buf);
  		decode_address(buf, cpu_pda[cpu].dcplb_doublefault_addr);
  		printk(KERN_NOTICE "   DCPLB_FAULT_ADDR: %s
  ", buf);
  		decode_address(buf, cpu_pda[cpu].icplb_doublefault_addr);
  		printk(KERN_NOTICE "   ICPLB_FAULT_ADDR: %s
  ", buf);

  		decode_address(buf, fp->retx);
  		printk(KERN_NOTICE "The instruction at %s caused a double exception
  ", buf);

  	} else

  #endif

  	{
  		dump_bfin_process(fp);
  		dump_bfin_mem(fp);
  		show_regs(fp);
  		dump_bfin_trace_buffer();

  	}

  #endif

  	panic("Double Fault - unrecoverable event");

  }

  void panic_cplb_error(int cplb_panic, struct pt_regs *fp)
  {
  	switch (cplb_panic) {
  	case CPLB_NO_UNLOCKED:
  		printk(KERN_EMERG "All CPLBs are locked
  ");
  		break;
  	case CPLB_PROT_VIOL:
  		return;
  	case CPLB_NO_ADDR_MATCH:
  		return;
  	case CPLB_UNKNOWN_ERR:
  		printk(KERN_EMERG "Unknown CPLB Exception
  ");
  		break;
  	}

  	oops_in_progress = 1;

  	dump_bfin_process(fp);

  	dump_bfin_mem(fp);

  	show_regs(fp);

  	dump_stack();

  	panic("Unrecoverable event");

  }

  
  #ifdef CONFIG_BUG
  int is_valid_bugaddr(unsigned long addr)
  {

  	unsigned int opcode;

  
  	if (!get_instruction(&opcode, (unsigned short *)addr))
  		return 0;
  
  	return opcode == BFIN_BUG_OPCODE;
  }
  #endif

  
  /* stub this out */
  #ifndef CONFIG_DEBUG_VERBOSE
  void show_regs(struct pt_regs *fp)
  {
  
  }
  #endif