traps.c

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/*
 * 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>
#include <asm/pda.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 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\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