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traps.c

/*
 * 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\n",
            trapnr, fp->ipend, fp->pc, fp->retx); */

      /* send the appropriate signal to the user program */
      switch (trapnr) {

      /* This table works in conjuction 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\n";
            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\n";
            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\n";
            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\n",
                  (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\n\n");
            else
#endif
                  dump_bfin_trace_buffer();

            if (oops_in_progress) {
                  /* Dump the current kernel stack */
                  verbose_printk(KERN_NOTICE "Kernel Stack\n");
                  show_stack(current, NULL);
                  print_modules();
#ifndef CONFIG_ACCESS_CHECK
                  verbose_printk(KERN_EMERG "Please turn on "
                         "CONFIG_ACCESS_CHECK\n");
#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\n");
                  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\n");
#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:\n",
                  (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\n", buf);
            decode_address(buf, cpu_pda[cpu].icplb_doublefault_addr);
            printk(KERN_NOTICE "   ICPLB_FAULT_ADDR: %s\n", buf);

            decode_address(buf, fp->retx);
            printk(KERN_NOTICE "The instruction at %s caused a double exception\n", 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\n");
            break;
      case CPLB_PROT_VIOL:
            return;
      case CPLB_NO_ADDR_MATCH:
            return;
      case CPLB_UNKNOWN_ERR:
            printk(KERN_EMERG "Unknown CPLB Exception\n");
            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

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