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[minix3.git] / minix / kernel / arch / i386 / exception.c

/* This file contains a simple exception handler.  Exceptions in user
 * processes are converted to signals. Exceptions in a kernel task cause
 * a panic.
 */

#include "kernel/kernel.h"
#include "arch_proto.h"
#include <signal.h>
#include <string.h>
#include <assert.h>
#include <machine/vm.h>

struct ex_s {
        char *msg;
        int signum;
        int minprocessor;
};

static struct ex_s ex_data[] = {
        { "Divide error", SIGFPE, 86 },
        { "Debug exception", SIGTRAP, 86 },
        { "Nonmaskable interrupt", SIGBUS, 86 },
        { "Breakpoint", SIGEMT, 86 },
        { "Overflow", SIGFPE, 86 },
        { "Bounds check", SIGFPE, 186 },
        { "Invalid opcode", SIGILL, 186 },
        { "Coprocessor not available", SIGFPE, 186 },
        { "Double fault", SIGBUS, 286 },
        { "Coprocessor segment overrun", SIGSEGV, 286 },
        { "Invalid TSS", SIGSEGV, 286 },
        { "Segment not present", SIGSEGV, 286 },
        { "Stack exception", SIGSEGV, 286 },    /* STACK_FAULT already used */
        { "General protection", SIGSEGV, 286 },
        { "Page fault", SIGSEGV, 386 },         /* not close */
        { NULL, SIGILL, 0 },                    /* probably software trap */
        { "Coprocessor error", SIGFPE, 386 },
        { "Alignment check", SIGBUS, 386 },
        { "Machine check", SIGBUS, 386 },
        { "SIMD exception", SIGFPE, 386 },
};

static void inkernel_disaster(struct proc *saved_proc,
        struct exception_frame *frame, struct ex_s *ep, int is_nested);

extern int catch_pagefaults;

static void proc_stacktrace_execute(struct proc *whichproc, reg_t v_bp, reg_t pc);

static void pagefault( struct proc *pr,
                        struct exception_frame * frame,
                        int is_nested)
{
        int in_physcopy = 0, in_memset = 0;

        reg_t pagefaultcr2;
        message m_pagefault;
        int err;

        pagefaultcr2 = read_cr2();

#if 0
        printf("kernel: pagefault in pr %d, addr 0x%lx, his cr3 0x%lx, actual cr3 0x%lx\n",
                pr->p_endpoint, pagefaultcr2, pr->p_seg.p_cr3, read_cr3());
#endif

        in_physcopy = (frame->eip > (vir_bytes) phys_copy) &&
           (frame->eip < (vir_bytes) phys_copy_fault);

        in_memset = (frame->eip > (vir_bytes) phys_memset) &&
           (frame->eip < (vir_bytes) memset_fault);

        if((is_nested || iskernelp(pr)) &&
                catch_pagefaults && (in_physcopy || in_memset)) {
#if 0
                printf("pf caught! addr 0x%lx\n", pagefaultcr2);
#endif
                if (is_nested) {
                        if(in_physcopy) {
                                assert(!in_memset);
                                frame->eip = (reg_t) phys_copy_fault_in_kernel;
                        } else {
                                frame->eip = (reg_t) memset_fault_in_kernel;
                        }
                }
                else {
                        pr->p_reg.pc = (reg_t) phys_copy_fault;
                        pr->p_reg.retreg = pagefaultcr2;
                }
        
                return;
        }

        if(is_nested) {
                printf("pagefault in kernel at pc 0x%lx address 0x%lx\n",
                        frame->eip, pagefaultcr2);
                inkernel_disaster(pr, frame, NULL, is_nested);
        }

        /* VM can't handle page faults. */
        if(pr->p_endpoint == VM_PROC_NR) {
                /* Page fault we can't / don't want to
                 * handle.
                 */
                printf("pagefault for VM on CPU %d, "
                        "pc = 0x%x, addr = 0x%x, flags = 0x%x, is_nested %d\n",
                        cpuid, pr->p_reg.pc, pagefaultcr2, frame->errcode,
                        is_nested);
                proc_stacktrace(pr);
                printf("pc of pagefault: 0x%lx\n", frame->eip);
                panic("pagefault in VM");

                return;
        }

        /* Don't schedule this process until pagefault is handled. */
        RTS_SET(pr, RTS_PAGEFAULT);

        /* tell Vm about the pagefault */
        m_pagefault.m_source = pr->p_endpoint;
        m_pagefault.m_type   = VM_PAGEFAULT;
        m_pagefault.VPF_ADDR = pagefaultcr2;
        m_pagefault.VPF_FLAGS = frame->errcode;

        if ((err = mini_send(pr, VM_PROC_NR,
                                        &m_pagefault, FROM_KERNEL))) {
                panic("WARNING: pagefault: mini_send returned %d\n", err);
        }

        return;
}

static void inkernel_disaster(struct proc *saved_proc,
        struct exception_frame * frame, struct ex_s *ep,
        int is_nested)
{
#if USE_SYSDEBUG
  if(ep) {
        if (ep->msg == NULL)
                printf("\nIntel-reserved exception %d\n", frame->vector);
          else
                printf("\n%s\n", ep->msg);
  }

  printf("cpu %d is_nested = %d ", cpuid, is_nested);

  printf("vec_nr= %d, trap_errno= 0x%x, eip= 0x%x, "
        "cs= 0x%x, eflags= 0x%x trap_esp 0x%08x\n",
        frame->vector, frame->errcode, frame->eip,
        frame->cs, frame->eflags, frame);
  printf("KERNEL registers :\n");
#define REG(n) (((u32_t *)frame)[-n])
  printf(
                  "\t%%eax 0x%08x %%ebx 0x%08x %%ecx 0x%08x %%edx 0x%08x\n"
                  "\t%%esp 0x%08x %%ebp 0x%08x %%esi 0x%08x %%edi 0x%08x\n",
                  REG(1), REG(2), REG(3), REG(4),
                  REG(5), REG(6), REG(7), REG(8));

  { 
        reg_t k_ebp = REG(6);
        printf("KERNEL stacktrace, starting with ebp = 0x%lx:\n", k_ebp);
        proc_stacktrace_execute(proc_addr(SYSTEM), k_ebp, frame->eip);
  }

  if (saved_proc) {
          printf("scheduled was: process %d (%s), ", saved_proc->p_endpoint, saved_proc->p_name);
          printf("pc = 0x%x\n", (unsigned) saved_proc->p_reg.pc);
          proc_stacktrace(saved_proc);

          panic("Unhandled kernel exception");
  }

  /* in an early stage of boot process we don't have processes yet */
  panic("exception in kernel while booting, no saved_proc yet");
#endif /* USE_SYSDEBUG */
}

/*===========================================================================*
 *                              exception                                    *
 *===========================================================================*/
void exception_handler(int is_nested, struct exception_frame * frame)
{
/* An exception or unexpected interrupt has occurred. */
  register struct ex_s *ep;
  struct proc *saved_proc;

  /* Save proc_ptr, because it may be changed by debug statements. */
  saved_proc = get_cpulocal_var(proc_ptr);
  
  ep = &ex_data[frame->vector];

  if (frame->vector == 2) {             /* spurious NMI on some machines */
        printf("got spurious NMI\n");
        return;
  }

  /*
   * handle special cases for nested problems as they might be tricky or filter
   * them out quickly if the traps are not nested
   */
  if (is_nested) {
        /*
         * if a problem occured while copying a message from userspace because
         * of a wrong pointer supplied by userland, handle it the only way we
         * can handle it ...
         */
        if (((void*)frame->eip >= (void*)copy_msg_to_user &&
                        (void*)frame->eip <= (void*)__copy_msg_to_user_end) ||
                        ((void*)frame->eip >= (void*)copy_msg_from_user &&
                        (void*)frame->eip <= (void*)__copy_msg_from_user_end)) {
                switch(frame->vector) {
                /* these error are expected */
                case PAGE_FAULT_VECTOR:
                case PROTECTION_VECTOR:
                        frame->eip = (reg_t) __user_copy_msg_pointer_failure;
                        return;
                default:
                        panic("Copy involving a user pointer failed unexpectedly!");
                }
        }

        /* Pass any error resulting from restoring FPU state, as a FPU
         * exception to the process.
         */
        if (((void*)frame->eip >= (void*)fxrstor &&
                        (void *)frame->eip <= (void*)__fxrstor_end) ||
                        ((void*)frame->eip >= (void*)frstor &&
                        (void *)frame->eip <= (void*)__frstor_end)) {
                frame->eip = (reg_t) __frstor_failure;
                return;
        }

        if(frame->vector == DEBUG_VECTOR
                && (saved_proc->p_reg.psw & TRACEBIT)
                && (saved_proc->p_seg.p_kern_trap_style == KTS_NONE)) {
                /* Getting a debug trap in the kernel is legitimate
                 * if a traced process entered the kernel using sysenter
                 * or syscall; the trap flag is not cleared then.
                 *
                 * It triggers on the first kernel entry so the trap
                 * style is still KTS_NONE.
                 */

                frame->eflags &= ~TRACEBIT;

                return;

                /* If control passes, this case is not recognized as legitimate
                 * and we panic later on after all.
                 */
        }
  }

  if(frame->vector == PAGE_FAULT_VECTOR) {
        pagefault(saved_proc, frame, is_nested);
        return;
  }

  /* If an exception occurs while running a process, the is_nested variable
   * will be zero. Exceptions in interrupt handlers or system traps will make
   * is_nested non-zero.
   */
  if (is_nested == 0 && ! iskernelp(saved_proc)) {
#if 0
        {

                printf(
  "vec_nr= %d, trap_errno= 0x%lx, eip= 0x%lx, cs= 0x%x, eflags= 0x%lx\n",
                        frame->vector, (unsigned long)frame->errcode,
                        (unsigned long)frame->eip, frame->cs,
                        (unsigned long)frame->eflags);
                proc_stacktrace(saved_proc);
        }

#endif
        cause_sig(proc_nr(saved_proc), ep->signum);
        return;
  }

  /* Exception in system code. This is not supposed to happen. */
  inkernel_disaster(saved_proc, frame, ep, is_nested);

  panic("return from inkernel_disaster");
}

#if USE_SYSDEBUG
/*===========================================================================*
 *                              proc_stacktrace_execute                      *
 *===========================================================================*/
static void proc_stacktrace_execute(struct proc *whichproc, reg_t v_bp, reg_t pc)
{
        reg_t v_hbp;
        int iskernel;
        int n = 0;

        iskernel = iskernelp(whichproc);

        printf("%-8.8s %6d 0x%lx ",
                whichproc->p_name, whichproc->p_endpoint, pc);

        while(v_bp) {
                reg_t v_pc;

#define PRCOPY(pr, pv, v, n) \
  (iskernel ? (memcpy((char *) v, (char *) pv, n), OK) : \
     data_copy(pr->p_endpoint, pv, KERNEL, (vir_bytes) (v), n))

                if(PRCOPY(whichproc, v_bp, &v_hbp, sizeof(v_hbp)) != OK) {
                        printf("(v_bp 0x%lx ?)", v_bp);
                        break;
                }
                if(PRCOPY(whichproc, v_bp + sizeof(v_pc), &v_pc, sizeof(v_pc)) != OK) {
                        printf("(v_pc 0x%lx ?)", v_bp + sizeof(v_pc));
                        break;
                }
                printf("0x%lx ", (unsigned long) v_pc);
                if(v_hbp != 0 && v_hbp <= v_bp) {
                        printf("(hbp 0x%lx ?)", v_hbp);
                        break;
                }
                v_bp = v_hbp;
                if(n++ > 50) {
                        printf("(truncated after %d steps) ", n);
                        break;
                }
        }
        printf("\n");
}
#endif /* USE_SYSDEBUG */

/*===========================================================================*
 *                              proc_stacktrace                      *
 *===========================================================================*/
void proc_stacktrace(struct proc *whichproc)
{
        u32_t use_bp;

        if(whichproc->p_seg.p_kern_trap_style == KTS_NONE) {
                printf("WARNING: stacktrace of running process\n");
        }

        switch(whichproc->p_seg.p_kern_trap_style) {
                case KTS_SYSENTER:
                case KTS_SYSCALL:
                {
                        u32_t sp = whichproc->p_reg.sp;

                        /* Full context is not available in the p_reg
                         * struct. Obtain it from the user's stack.
                         * The use stack pointer is always available.
                         * The fact that it's there, and the 16 byte offset,
                         * is a dependency on the trap code in
                         * kernel/arch/i386/usermapped_glo_ipc.S.
                         */

                        if(data_copy(whichproc->p_endpoint, sp+16,
                          KERNEL, (vir_bytes) &use_bp,
                                sizeof(use_bp)) != OK) {
                                printf("stacktrace: aborting, copy failed\n");
                                return;
                        }

                        break;
                }
                default:
                        /* Full context is available; use the stored ebp */
                        use_bp = whichproc->p_reg.fp;
                        break;
        }

#if USE_SYSDEBUG
        proc_stacktrace_execute(whichproc, use_bp, whichproc->p_reg.pc);
#endif /* USE_SYSDEBUG */
}

void enable_fpu_exception(void)
{
        u32_t cr0 = read_cr0();
        if(!(cr0 & I386_CR0_TS))
                write_cr0(cr0 | I386_CR0_TS);
}

void disable_fpu_exception(void)
{
        clts();
}