No empty .Rs/.Re

[netbsd-mini2440.git] / sys / arch / arm / arm32 / fault.c

/*      $NetBSD: fault.c,v 1.73 2009/11/21 20:32:18 rmind Exp $ */

/*
 * Copyright 2003 Wasabi Systems, Inc.
 * All rights reserved.
 *
 * Written by Steve C. Woodford for Wasabi Systems, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed for the NetBSD Project by
 *      Wasabi Systems, Inc.
 * 4. The name of Wasabi Systems, Inc. may not be used to endorse
 *    or promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL WASABI SYSTEMS, INC
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
/*
 * Copyright (c) 1994-1997 Mark Brinicombe.
 * Copyright (c) 1994 Brini.
 * All rights reserved.
 *
 * This code is derived from software written for Brini by Mark Brinicombe
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Brini.
 * 4. The name of the company nor the name of the author may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY BRINI ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL BRINI OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * RiscBSD kernel project
 *
 * fault.c
 *
 * Fault handlers
 *
 * Created      : 28/11/94
 */

#include "opt_ddb.h"
#include "opt_kgdb.h"
#include "opt_sa.h"

#include <sys/types.h>
__KERNEL_RCSID(0, "$NetBSD: fault.c,v 1.73 2009/11/21 20:32:18 rmind Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/kauth.h>

#include <sys/savar.h>
#include <sys/cpu.h>

#include <uvm/uvm_extern.h>
#include <uvm/uvm_stat.h>
#ifdef UVMHIST
#include <uvm/uvm.h>
#endif

#include <arm/cpuconf.h>

#include <machine/frame.h>
#include <arm/arm32/katelib.h>
#include <machine/intr.h>
#if defined(DDB) || defined(KGDB)
#include <machine/db_machdep.h>
#ifdef KGDB
#include <sys/kgdb.h>
#endif
#if !defined(DDB)
#define kdb_trap        kgdb_trap
#endif
#endif

#include <arch/arm/arm/disassem.h>
#include <arm/arm32/machdep.h>
 
extern char fusubailout[];

#ifdef DEBUG
int last_fault_code;    /* For the benefit of pmap_fault_fixup() */
#endif

#if defined(CPU_ARM3) || defined(CPU_ARM6) || \
    defined(CPU_ARM7) || defined(CPU_ARM7TDMI)
/* These CPUs may need data/prefetch abort fixups */
#define CPU_ABORT_FIXUP_REQUIRED
#endif

struct data_abort {
        int (*func)(trapframe_t *, u_int, u_int, struct lwp *, ksiginfo_t *);
        const char *desc;
};

static int dab_fatal(trapframe_t *, u_int, u_int, struct lwp *, ksiginfo_t *);
static int dab_align(trapframe_t *, u_int, u_int, struct lwp *, ksiginfo_t *);
static int dab_buserr(trapframe_t *, u_int, u_int, struct lwp *, ksiginfo_t *);

static const struct data_abort data_aborts[] = {
        {dab_fatal,     "Vector Exception"},
        {dab_align,     "Alignment Fault 1"},
        {dab_fatal,     "Terminal Exception"},
        {dab_align,     "Alignment Fault 3"},
        {dab_buserr,    "External Linefetch Abort (S)"},
        {NULL,          "Translation Fault (S)"},
        {dab_buserr,    "External Linefetch Abort (P)"},
        {NULL,          "Translation Fault (P)"},
        {dab_buserr,    "External Non-Linefetch Abort (S)"},
        {NULL,          "Domain Fault (S)"},
        {dab_buserr,    "External Non-Linefetch Abort (P)"},
        {NULL,          "Domain Fault (P)"},
        {dab_buserr,    "External Translation Abort (L1)"},
        {NULL,          "Permission Fault (S)"},
        {dab_buserr,    "External Translation Abort (L2)"},
        {NULL,          "Permission Fault (P)"}
};

/* Determine if a fault came from user mode */
#define TRAP_USERMODE(tf)       ((tf->tf_spsr & PSR_MODE) == PSR_USR32_MODE)

/* Determine if 'x' is a permission fault */
#define IS_PERMISSION_FAULT(x)                                  \
        (((1 << ((x) & FAULT_TYPE_MASK)) &                      \
          ((1 << FAULT_PERM_P) | (1 << FAULT_PERM_S))) != 0)

#if 0
/* maybe one day we'll do emulations */
#define TRAPSIGNAL(l,k) (*(l)->l_proc->p_emul->e_trapsignal)((l), (k))
#else
#define TRAPSIGNAL(l,k) trapsignal((l), (k))
#endif

static inline void
call_trapsignal(struct lwp *l, ksiginfo_t *ksi)
{

        TRAPSIGNAL(l, ksi);
}

static inline int
data_abort_fixup(trapframe_t *tf, u_int fsr, u_int far, struct lwp *l)
{
#ifdef CPU_ABORT_FIXUP_REQUIRED
        int error;

        /* Call the CPU specific data abort fixup routine */
        error = cpu_dataabt_fixup(tf);
        if (__predict_true(error != ABORT_FIXUP_FAILED))
                return (error);

        /*
         * Oops, couldn't fix up the instruction
         */
        printf("data_abort_fixup: fixup for %s mode data abort failed.\n",
            TRAP_USERMODE(tf) ? "user" : "kernel");
#ifdef THUMB_CODE
        if (tf->tf_spsr & PSR_T_bit) {
                printf("pc = 0x%08x, opcode 0x%04x, 0x%04x, insn = ",
                    tf->tf_pc, *((u_int16 *)(tf->tf_pc & ~1)),
                    *((u_int16 *)((tf->tf_pc + 2) & ~1)));
        }
        else
#endif
        {
                printf("pc = 0x%08x, opcode 0x%08x, insn = ", tf->tf_pc,
                    *((u_int *)tf->tf_pc));
        }
        disassemble(tf->tf_pc);

        /* Die now if this happened in kernel mode */
        if (!TRAP_USERMODE(tf))
                dab_fatal(tf, fsr, far, l, NULL);

        return (error);
#else
        return (ABORT_FIXUP_OK);
#endif /* CPU_ABORT_FIXUP_REQUIRED */
}

void
data_abort_handler(trapframe_t *tf)
{
        struct vm_map *map;
        struct pcb *pcb;
        struct lwp *l;
        u_int user, far, fsr;
        vm_prot_t ftype;
        void *onfault;
        vaddr_t va;
        int error;
        ksiginfo_t ksi;

        UVMHIST_FUNC("data_abort_handler"); 

        /* Grab FAR/FSR before enabling interrupts */
        far = cpu_faultaddress();
        fsr = cpu_faultstatus();

        UVMHIST_CALLED(maphist);
        /* Update vmmeter statistics */
        uvmexp.traps++;

        /* Re-enable interrupts if they were enabled previously */
        KASSERT(!TRAP_USERMODE(tf) || (tf->tf_spsr & IF32_bits) == 0);
        if (__predict_true((tf->tf_spsr & IF32_bits) != IF32_bits))
                restore_interrupts(tf->tf_spsr & IF32_bits);

        /* Get the current lwp structure */
        KASSERT(curlwp != NULL);
        l = curlwp;

        UVMHIST_LOG(maphist, " (pc=0x%x, l=0x%x, far=0x%x, fsr=0x%x)",
            tf->tf_pc, l, far, fsr);

        /* Data abort came from user mode? */
        if ((user = TRAP_USERMODE(tf)) != 0)
                LWP_CACHE_CREDS(l, l->l_proc);

        /* Grab the current pcb */
        pcb = lwp_getpcb(l);

        /* Invoke the appropriate handler, if necessary */
        if (__predict_false(data_aborts[fsr & FAULT_TYPE_MASK].func != NULL)) {
                if ((data_aborts[fsr & FAULT_TYPE_MASK].func)(tf, fsr, far,
                    l, &ksi))
                        goto do_trapsignal;
                goto out;
        }

        /*
         * At this point, we're dealing with one of the following data aborts:
         *
         *  FAULT_TRANS_S  - Translation -- Section
         *  FAULT_TRANS_P  - Translation -- Page
         *  FAULT_DOMAIN_S - Domain -- Section
         *  FAULT_DOMAIN_P - Domain -- Page
         *  FAULT_PERM_S   - Permission -- Section
         *  FAULT_PERM_P   - Permission -- Page
         *
         * These are the main virtual memory-related faults signalled by
         * the MMU.
         */

        /* fusubailout is used by [fs]uswintr to avoid page faulting */
        if (__predict_false(pcb->pcb_onfault == fusubailout)) {
                tf->tf_r0 = EFAULT;
                tf->tf_pc = (register_t)(intptr_t) pcb->pcb_onfault;
                return;
        }

        if (user) {
                pcb->pcb_tf = tf;
        }

        /*
         * Make sure the Program Counter is sane. We could fall foul of
         * someone executing Thumb code, in which case the PC might not
         * be word-aligned. This would cause a kernel alignment fault
         * further down if we have to decode the current instruction.
         */
#ifdef THUMB_CODE
        /* 
         * XXX: It would be nice to be able to support Thumb in the kernel
         * at some point.
         */
        if (__predict_false(!user && (tf->tf_pc & 3) != 0)) {
                printf("\ndata_abort_fault: Misaligned Kernel-mode "
                    "Program Counter\n");
                dab_fatal(tf, fsr, far, l, NULL);
        }
#else
        if (__predict_false((tf->tf_pc & 3) != 0)) {
                if (user) {
                        /*
                         * Give the user an illegal instruction signal.
                         */
                        /* Deliver a SIGILL to the process */
                        KSI_INIT_TRAP(&ksi);
                        ksi.ksi_signo = SIGILL;
                        ksi.ksi_code = ILL_ILLOPC;
                        ksi.ksi_addr = (u_int32_t *)(intptr_t) far;
                        ksi.ksi_trap = fsr;
                        goto do_trapsignal;
                }

                /*
                 * The kernel never executes Thumb code.
                 */
                printf("\ndata_abort_fault: Misaligned Kernel-mode "
                    "Program Counter\n");
                dab_fatal(tf, fsr, far, l, NULL);
        }
#endif

        /* See if the CPU state needs to be fixed up */
        switch (data_abort_fixup(tf, fsr, far, l)) {
        case ABORT_FIXUP_RETURN:
                return;
        case ABORT_FIXUP_FAILED:
                /* Deliver a SIGILL to the process */
                KSI_INIT_TRAP(&ksi);
                ksi.ksi_signo = SIGILL;
                ksi.ksi_code = ILL_ILLOPC;
                ksi.ksi_addr = (u_int32_t *)(intptr_t) far;
                ksi.ksi_trap = fsr;
                goto do_trapsignal;
        default:
                break;
        }

        va = trunc_page((vaddr_t)far);

        /*
         * It is only a kernel address space fault iff:
         *      1. user == 0  and
         *      2. pcb_onfault not set or
         *      3. pcb_onfault set and not LDRT/LDRBT/STRT/STRBT instruction.
         */
        if (user == 0 && (va >= VM_MIN_KERNEL_ADDRESS ||
            (va < VM_MIN_ADDRESS && vector_page == ARM_VECTORS_LOW)) &&
            __predict_true((pcb->pcb_onfault == NULL ||
             (ReadWord(tf->tf_pc) & 0x05200000) != 0x04200000))) {
                map = kernel_map;

                /* Was the fault due to the FPE/IPKDB ? */
                if (__predict_false((tf->tf_spsr & PSR_MODE)==PSR_UND32_MODE)) {
                        KSI_INIT_TRAP(&ksi);
                        ksi.ksi_signo = SIGSEGV;
                        ksi.ksi_code = SEGV_ACCERR;
                        ksi.ksi_addr = (u_int32_t *)(intptr_t) far;
                        ksi.ksi_trap = fsr;

                        /*
                         * Force exit via userret()
                         * This is necessary as the FPE is an extension to
                         * userland that actually runs in a priveledged mode
                         * but uses USR mode permissions for its accesses.
                         */
                        user = 1;
                        goto do_trapsignal;
                }
        } else {
                map = &l->l_proc->p_vmspace->vm_map;
#ifdef KERN_SA
                if ((l->l_flag & LW_SA) && (~l->l_pflag & LP_SA_NOBLOCK)) {
                        l->l_savp->savp_faultaddr = (vaddr_t)far;
                        l->l_pflag |= LP_SA_PAGEFAULT;
                }
#endif
        }

        /*
         * We need to know whether the page should be mapped
         * as R or R/W. The MMU does not give us the info as
         * to whether the fault was caused by a read or a write.
         *
         * However, we know that a permission fault can only be
         * the result of a write to a read-only location, so
         * we can deal with those quickly.
         *
         * Otherwise we need to disassemble the instruction
         * responsible to determine if it was a write.
         */
        if (IS_PERMISSION_FAULT(fsr))
                ftype = VM_PROT_WRITE; 
        else {
#ifdef THUMB_CODE
                /* Fast track the ARM case.  */
                if (__predict_false(tf->tf_spsr & PSR_T_bit)) {
                        u_int insn = fusword((void *)(tf->tf_pc & ~1));
                        u_int insn_f8 = insn & 0xf800;
                        u_int insn_fe = insn & 0xfe00;

                        if (insn_f8 == 0x6000 || /* STR(1) */
                            insn_f8 == 0x7000 || /* STRB(1) */
                            insn_f8 == 0x8000 || /* STRH(1) */
                            insn_f8 == 0x9000 || /* STR(3) */
                            insn_f8 == 0xc000 || /* STM */
                            insn_fe == 0x5000 || /* STR(2) */
                            insn_fe == 0x5200 || /* STRH(2) */
                            insn_fe == 0x5400)   /* STRB(2) */
                                ftype = VM_PROT_WRITE;
                        else
                                ftype = VM_PROT_READ;
                }
                else
#endif
                {
                        u_int insn = ReadWord(tf->tf_pc);

                        if (((insn & 0x0c100000) == 0x04000000) || /* STR[B] */
                            ((insn & 0x0e1000b0) == 0x000000b0) || /* STR[HD]*/
                            ((insn & 0x0a100000) == 0x08000000))   /* STM/CDT*/
                                ftype = VM_PROT_WRITE; 
                        else if ((insn & 0x0fb00ff0) == 0x01000090)/* SWP */
                                ftype = VM_PROT_READ | VM_PROT_WRITE; 
                        else
                                ftype = VM_PROT_READ; 
                }
        }

        /*
         * See if the fault is as a result of ref/mod emulation,
         * or domain mismatch.
         */
#ifdef DEBUG
        last_fault_code = fsr;
#endif
        if (pmap_fault_fixup(map->pmap, va, ftype, user)) {
#ifdef KERN_SA
                if (map != kernel_map)
                        l->l_pflag &= ~LP_SA_PAGEFAULT;
#endif
                UVMHIST_LOG(maphist, " <- ref/mod emul", 0, 0, 0, 0);
                goto out;
        }

        if (__predict_false(curcpu()->ci_intr_depth > 0)) {
                if (pcb->pcb_onfault) {
                        tf->tf_r0 = EINVAL;
                        tf->tf_pc = (register_t)(intptr_t) pcb->pcb_onfault;
                        return;
                }
                printf("\nNon-emulated page fault with intr_depth > 0\n");
                dab_fatal(tf, fsr, far, l, NULL);
        }

        onfault = pcb->pcb_onfault;
        pcb->pcb_onfault = NULL;
        error = uvm_fault(map, va, ftype);
        pcb->pcb_onfault = onfault;

#ifdef KERN_SA
        if (map != kernel_map)
                l->l_pflag &= ~LP_SA_PAGEFAULT;
#endif

        if (__predict_true(error == 0)) {
                if (user)
                        uvm_grow(l->l_proc, va); /* Record any stack growth */
                UVMHIST_LOG(maphist, " <- uvm", 0, 0, 0, 0);
                goto out;
        }

        if (user == 0) {
                if (pcb->pcb_onfault) {
                        tf->tf_r0 = error;
                        tf->tf_pc = (register_t)(intptr_t) pcb->pcb_onfault;
                        return;
                }

                printf("\nuvm_fault(%p, %lx, %x) -> %x\n", map, va, ftype,
                    error);
                dab_fatal(tf, fsr, far, l, NULL);
        }

        KSI_INIT_TRAP(&ksi);

        if (error == ENOMEM) {
                printf("UVM: pid %d (%s), uid %d killed: "
                    "out of swap\n", l->l_proc->p_pid, l->l_proc->p_comm,
                    l->l_cred ? kauth_cred_geteuid(l->l_cred) : -1);
                ksi.ksi_signo = SIGKILL;
        } else
                ksi.ksi_signo = SIGSEGV;

        ksi.ksi_code = (error == EACCES) ? SEGV_ACCERR : SEGV_MAPERR;
        ksi.ksi_addr = (u_int32_t *)(intptr_t) far;
        ksi.ksi_trap = fsr;
        UVMHIST_LOG(maphist, " <- error (%d)", error, 0, 0, 0);

do_trapsignal:
        call_trapsignal(l, &ksi);
out:
        /* If returning to user mode, make sure to invoke userret() */
        if (user)
                userret(l);
}

/*
 * dab_fatal() handles the following data aborts:
 *
 *  FAULT_WRTBUF_0 - Vector Exception
 *  FAULT_WRTBUF_1 - Terminal Exception
 *
 * We should never see these on a properly functioning system.
 *
 * This function is also called by the other handlers if they
 * detect a fatal problem.
 *
 * Note: If 'l' is NULL, we assume we're dealing with a prefetch abort.
 */
static int
dab_fatal(trapframe_t *tf, u_int fsr, u_int far, struct lwp *l, ksiginfo_t *ksi)
{
        const char *mode;

        mode = TRAP_USERMODE(tf) ? "user" : "kernel";

        if (l != NULL) {
                printf("Fatal %s mode data abort: '%s'\n", mode,
                    data_aborts[fsr & FAULT_TYPE_MASK].desc);
                printf("trapframe: %p\nFSR=%08x, FAR=", tf, fsr);
                if ((fsr & FAULT_IMPRECISE) == 0)
                        printf("%08x, ", far);
                else
                        printf("Invalid,  ");
                printf("spsr=%08x\n", tf->tf_spsr);
        } else {
                printf("Fatal %s mode prefetch abort at 0x%08x\n",
                    mode, tf->tf_pc);
                printf("trapframe: %p, spsr=%08x\n", tf, tf->tf_spsr);
        }

        printf("r0 =%08x, r1 =%08x, r2 =%08x, r3 =%08x\n",
            tf->tf_r0, tf->tf_r1, tf->tf_r2, tf->tf_r3);
        printf("r4 =%08x, r5 =%08x, r6 =%08x, r7 =%08x\n",
            tf->tf_r4, tf->tf_r5, tf->tf_r6, tf->tf_r7);
        printf("r8 =%08x, r9 =%08x, r10=%08x, r11=%08x\n",
            tf->tf_r8, tf->tf_r9, tf->tf_r10, tf->tf_r11);
        printf("r12=%08x, ", tf->tf_r12);

        if (TRAP_USERMODE(tf))
                printf("usp=%08x, ulr=%08x",
                    tf->tf_usr_sp, tf->tf_usr_lr);
        else
                printf("ssp=%08x, slr=%08x",
                    tf->tf_svc_sp, tf->tf_svc_lr);
        printf(", pc =%08x\n\n", tf->tf_pc);

#if defined(DDB) || defined(KGDB)
        kdb_trap(T_FAULT, tf);
#endif
        panic("Fatal abort");
        /*NOTREACHED*/
}

/*
 * dab_align() handles the following data aborts:
 *
 *  FAULT_ALIGN_0 - Alignment fault
 *  FAULT_ALIGN_0 - Alignment fault
 *
 * These faults are fatal if they happen in kernel mode. Otherwise, we
 * deliver a bus error to the process.
 */
static int
dab_align(trapframe_t *tf, u_int fsr, u_int far, struct lwp *l, ksiginfo_t *ksi)
{
        struct pcb *pcb = lwp_getpcb(l);

        /* Alignment faults are always fatal if they occur in kernel mode */
        if (!TRAP_USERMODE(tf))
                dab_fatal(tf, fsr, far, l, NULL);

        /* pcb_onfault *must* be NULL at this point */
        KDASSERT(pcb->pcb_onfault == NULL);

        /* See if the CPU state needs to be fixed up */
        (void) data_abort_fixup(tf, fsr, far, l);

        /* Deliver a bus error signal to the process */
        KSI_INIT_TRAP(ksi);
        ksi->ksi_signo = SIGBUS;
        ksi->ksi_code = BUS_ADRALN;
        ksi->ksi_addr = (u_int32_t *)(intptr_t)far;
        ksi->ksi_trap = fsr;

        pcb->pcb_tf = tf;

        return (1);
}

/*
 * dab_buserr() handles the following data aborts:
 *
 *  FAULT_BUSERR_0 - External Abort on Linefetch -- Section
 *  FAULT_BUSERR_1 - External Abort on Linefetch -- Page
 *  FAULT_BUSERR_2 - External Abort on Non-linefetch -- Section
 *  FAULT_BUSERR_3 - External Abort on Non-linefetch -- Page
 *  FAULT_BUSTRNL1 - External abort on Translation -- Level 1
 *  FAULT_BUSTRNL2 - External abort on Translation -- Level 2
 *
 * If pcb_onfault is set, flag the fault and return to the handler.
 * If the fault occurred in user mode, give the process a SIGBUS.
 *
 * Note: On XScale, FAULT_BUSERR_0, FAULT_BUSERR_1, and FAULT_BUSERR_2
 * can be flagged as imprecise in the FSR. This causes a real headache
 * since some of the machine state is lost. In this case, tf->tf_pc
 * may not actually point to the offending instruction. In fact, if
 * we've taken a double abort fault, it generally points somewhere near
 * the top of "data_abort_entry" in exception.S.
 *
 * In all other cases, these data aborts are considered fatal.
 */
static int
dab_buserr(trapframe_t *tf, u_int fsr, u_int far, struct lwp *l,
    ksiginfo_t *ksi)
{
        struct pcb *pcb = lwp_getpcb(l);

#ifdef __XSCALE__
        if ((fsr & FAULT_IMPRECISE) != 0 &&
            (tf->tf_spsr & PSR_MODE) == PSR_ABT32_MODE) {
                /*
                 * Oops, an imprecise, double abort fault. We've lost the
                 * r14_abt/spsr_abt values corresponding to the original
                 * abort, and the spsr saved in the trapframe indicates
                 * ABT mode.
                 */
                tf->tf_spsr &= ~PSR_MODE;

                /*
                 * We use a simple heuristic to determine if the double abort
                 * happened as a result of a kernel or user mode access.
                 * If the current trapframe is at the top of the kernel stack,
                 * the fault _must_ have come from user mode.
                 */
                if (tf != ((trapframe_t *)pcb->pcb_un.un_32.pcb32_sp) - 1) {
                        /*
                         * Kernel mode. We're either about to die a
                         * spectacular death, or pcb_onfault will come
                         * to our rescue. Either way, the current value
                         * of tf->tf_pc is irrelevant.
                         */
                        tf->tf_spsr |= PSR_SVC32_MODE;
                        if (pcb->pcb_onfault == NULL)
                                printf("\nKernel mode double abort!\n");
                } else {
                        /*
                         * User mode. We've lost the program counter at the
                         * time of the fault (not that it was accurate anyway;
                         * it's not called an imprecise fault for nothing).
                         * About all we can do is copy r14_usr to tf_pc and
                         * hope for the best. The process is about to get a
                         * SIGBUS, so it's probably history anyway.
                         */
                        tf->tf_spsr |= PSR_USR32_MODE;
                        tf->tf_pc = tf->tf_usr_lr;
#ifdef THUMB_CODE
                        tf->tf_spsr &= ~PSR_T_bit;
                        if (tf->tf_usr_lr & 1)
                                tf->tf_spsr |= PSR_T_bit;
#endif
                }
        }

        /* FAR is invalid for imprecise exceptions */
        if ((fsr & FAULT_IMPRECISE) != 0)
                far = 0;
#endif /* __XSCALE__ */

        if (pcb->pcb_onfault) {
                KDASSERT(TRAP_USERMODE(tf) == 0);
                tf->tf_r0 = EFAULT;
                tf->tf_pc = (register_t)(intptr_t) pcb->pcb_onfault;
                return (0);
        }

        /* See if the CPU state needs to be fixed up */
        (void) data_abort_fixup(tf, fsr, far, l);

        /*
         * At this point, if the fault happened in kernel mode, we're toast
         */
        if (!TRAP_USERMODE(tf))
                dab_fatal(tf, fsr, far, l, NULL);

        /* Deliver a bus error signal to the process */
        KSI_INIT_TRAP(ksi);
        ksi->ksi_signo = SIGBUS;
        ksi->ksi_code = BUS_ADRERR;
        ksi->ksi_addr = (u_int32_t *)(intptr_t)far;
        ksi->ksi_trap = fsr;

        pcb->pcb_tf = tf;

        return (1);
}

static inline int
prefetch_abort_fixup(trapframe_t *tf)
{
#ifdef CPU_ABORT_FIXUP_REQUIRED
        int error;

        /* Call the CPU specific prefetch abort fixup routine */
        error = cpu_prefetchabt_fixup(tf);
        if (__predict_true(error != ABORT_FIXUP_FAILED))
                return (error);

        /*
         * Oops, couldn't fix up the instruction
         */
        printf(
            "prefetch_abort_fixup: fixup for %s mode prefetch abort failed.\n",
            TRAP_USERMODE(tf) ? "user" : "kernel");
#ifdef THUMB_CODE
        if (tf->tf_spsr & PSR_T_bit) {
                printf("pc = 0x%08x, opcode 0x%04x, 0x%04x, insn = ",
                    tf->tf_pc, *((u_int16 *)(tf->tf_pc & ~1),
                    *((u_int16 *)((tf->tf_pc + 2) & ~1));
        }
        else
#endif
        {
                printf("pc = 0x%08x, opcode 0x%08x, insn = ", tf->tf_pc,
                    *((u_int *)tf->tf_pc));
        }
        disassemble(tf->tf_pc);

        /* Die now if this happened in kernel mode */
        if (!TRAP_USERMODE(tf))
                dab_fatal(tf, 0, tf->tf_pc, NULL, NULL);

        return (error);
#else
        return (ABORT_FIXUP_OK);
#endif /* CPU_ABORT_FIXUP_REQUIRED */
}

/*
 * void prefetch_abort_handler(trapframe_t *tf)
 *
 * Abort handler called when instruction execution occurs at
 * a non existent or restricted (access permissions) memory page.
 * If the address is invalid and we were in SVC mode then panic as
 * the kernel should never prefetch abort.
 * If the address is invalid and the page is mapped then the user process
 * does no have read permission so send it a signal.
 * Otherwise fault the page in and try again.
 */
void
prefetch_abort_handler(trapframe_t *tf)
{
        struct lwp *l;
        struct pcb *pcb;
        struct vm_map *map;
        vaddr_t fault_pc, va;
        ksiginfo_t ksi;
        int error, user;

        UVMHIST_FUNC("prefetch_abort_handler"); UVMHIST_CALLED(maphist);

        /* Update vmmeter statistics */
        uvmexp.traps++;

        l = curlwp;
        pcb = lwp_getpcb(l);

        if ((user = TRAP_USERMODE(tf)) != 0)
                LWP_CACHE_CREDS(l, l->l_proc);

        /*
         * Enable IRQ's (disabled by the abort) This always comes
         * from user mode so we know interrupts were not disabled.
         * But we check anyway.
         */
        KASSERT(!TRAP_USERMODE(tf) || (tf->tf_spsr & IF32_bits) == 0);
        if (__predict_true((tf->tf_spsr & I32_bit) != IF32_bits))
                restore_interrupts(tf->tf_spsr & IF32_bits);

        /* See if the CPU state needs to be fixed up */
        switch (prefetch_abort_fixup(tf)) {
        case ABORT_FIXUP_RETURN:
                KASSERT(!TRAP_USERMODE(tf) || (tf->tf_spsr & IF32_bits) == 0);
                return;
        case ABORT_FIXUP_FAILED:
                /* Deliver a SIGILL to the process */
                KSI_INIT_TRAP(&ksi);
                ksi.ksi_signo = SIGILL;
                ksi.ksi_code = ILL_ILLOPC;
                ksi.ksi_addr = (u_int32_t *)(intptr_t) tf->tf_pc;
                pcb->pcb_tf = tf;
                goto do_trapsignal;
        default:
                break;
        }

        /* Prefetch aborts cannot happen in kernel mode */
        if (__predict_false(!user))
                dab_fatal(tf, 0, tf->tf_pc, NULL, NULL);

        /* Get fault address */
        fault_pc = tf->tf_pc;
        pcb->pcb_tf = tf;
        UVMHIST_LOG(maphist, " (pc=0x%x, l=0x%x, tf=0x%x)", fault_pc, l, tf,
            0);

        /* Ok validate the address, can only execute in USER space */
        if (__predict_false(fault_pc >= VM_MAXUSER_ADDRESS ||
            (fault_pc < VM_MIN_ADDRESS && vector_page == ARM_VECTORS_LOW))) {
                KSI_INIT_TRAP(&ksi);
                ksi.ksi_signo = SIGSEGV;
                ksi.ksi_code = SEGV_ACCERR;
                ksi.ksi_addr = (u_int32_t *)(intptr_t) fault_pc;
                ksi.ksi_trap = fault_pc;
                goto do_trapsignal;
        }

        map = &l->l_proc->p_vmspace->vm_map;
        va = trunc_page(fault_pc);

        /*
         * See if the pmap can handle this fault on its own...
         */
#ifdef DEBUG
        last_fault_code = -1;
#endif
        if (pmap_fault_fixup(map->pmap, va, VM_PROT_READ, 1)) {
                UVMHIST_LOG (maphist, " <- emulated", 0, 0, 0, 0);
                goto out;
        }

#ifdef DIAGNOSTIC
        if (__predict_false(l->l_cpu->ci_intr_depth > 0)) {
                printf("\nNon-emulated prefetch abort with intr_depth > 0\n");
                dab_fatal(tf, 0, tf->tf_pc, NULL, NULL);
        }
#endif

#ifdef KERN_SA
        if (map != kernel_map && (l->l_flag & LW_SA)) {
                l->l_savp->savp_faultaddr = fault_pc;
                l->l_pflag |= LP_SA_PAGEFAULT;
        }
#endif

        error = uvm_fault(map, va, VM_PROT_READ);

#ifdef KERN_SA
        if (map != kernel_map)
                l->l_pflag &= ~LP_SA_PAGEFAULT;
#endif

        if (__predict_true(error == 0)) {
                UVMHIST_LOG (maphist, " <- uvm", 0, 0, 0, 0);
                goto out;
        }
        KSI_INIT_TRAP(&ksi);

        UVMHIST_LOG (maphist, " <- fatal (%d)", error, 0, 0, 0);
        if (error == ENOMEM) {
                printf("UVM: pid %d (%s), uid %d killed: "
                    "out of swap\n", l->l_proc->p_pid, l->l_proc->p_comm,
                    l->l_cred ? kauth_cred_geteuid(l->l_cred) : -1);
                ksi.ksi_signo = SIGKILL;
        } else
                ksi.ksi_signo = SIGSEGV;

        ksi.ksi_code = SEGV_MAPERR;
        ksi.ksi_addr = (u_int32_t *)(intptr_t) fault_pc;
        ksi.ksi_trap = fault_pc;

do_trapsignal:
        call_trapsignal(l, &ksi);

out:
        KASSERT(!TRAP_USERMODE(tf) || (tf->tf_spsr & IF32_bits) == 0);
        userret(l);
}

/*
 * Tentatively read an 8, 16, or 32-bit value from 'addr'.
 * If the read succeeds, the value is written to 'rptr' and zero is returned.
 * Else, return EFAULT.
 */
int
badaddr_read(void *addr, size_t size, void *rptr)
{
        extern int badaddr_read_1(const uint8_t *, uint8_t *);
        extern int badaddr_read_2(const uint16_t *, uint16_t *);
        extern int badaddr_read_4(const uint32_t *, uint32_t *);
        union {
                uint8_t v1;
                uint16_t v2;
                uint32_t v4;
        } u;
        struct pcb *curpcb_save;
        int rv, s;

        cpu_drain_writebuf();

        /*
         * We might be called at interrupt time, so arrange to steal
         * lwp0's PCB temporarily, if required, so that pcb_onfault
         * handling works correctly.
         */
        s = splhigh();
        if ((curpcb_save = curpcb) == NULL)
                curpcb = lwp_getpcb(&lwp0);

        /* Read from the test address. */
        switch (size) {
        case sizeof(uint8_t):
                rv = badaddr_read_1(addr, &u.v1);
                if (rv == 0 && rptr)
                        *(uint8_t *) rptr = u.v1;
                break;

        case sizeof(uint16_t):
                rv = badaddr_read_2(addr, &u.v2);
                if (rv == 0 && rptr)
                        *(uint16_t *) rptr = u.v2;
                break;

        case sizeof(uint32_t):
                rv = badaddr_read_4(addr, &u.v4);
                if (rv == 0 && rptr)
                        *(uint32_t *) rptr = u.v4;
                break;

        default:
                curpcb = curpcb_save;
                panic("badaddr: invalid size (%lu)", (u_long) size);
        }

        /* Restore curpcb */
        curpcb = curpcb_save;
        splx(s);

        /* Return EFAULT if the address was invalid, else zero */
        return (rv);
}