604046faf3
. restore state depends on how saving of state was done; also remember trap style in sig context . actually set and restore TRACEBIT with new trap styles; have to remove it once process enters kernel though, done in debug trap exception handler . introduce MF_STEP that makes arch-specific code turn on trace bit instead of setting TRACEBIT directly, a bit more arch-friendly and avoids keeping precious state in per-process PSW arch-dependently
387 lines
10 KiB
C
387 lines
10 KiB
C
/* This file contains a simple exception handler. Exceptions in user
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* processes are converted to signals. Exceptions in a kernel task cause
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* a panic.
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*/
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#include "kernel/kernel.h"
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#include "arch_proto.h"
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#include <signal.h>
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#include <string.h>
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#include <assert.h>
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#include <machine/vm.h>
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struct ex_s {
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char *msg;
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int signum;
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int minprocessor;
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};
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static struct ex_s ex_data[] = {
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{ "Divide error", SIGFPE, 86 },
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{ "Debug exception", SIGTRAP, 86 },
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{ "Nonmaskable interrupt", SIGBUS, 86 },
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{ "Breakpoint", SIGEMT, 86 },
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{ "Overflow", SIGFPE, 86 },
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{ "Bounds check", SIGFPE, 186 },
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{ "Invalid opcode", SIGILL, 186 },
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{ "Coprocessor not available", SIGFPE, 186 },
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{ "Double fault", SIGBUS, 286 },
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{ "Coprocessor segment overrun", SIGSEGV, 286 },
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{ "Invalid TSS", SIGSEGV, 286 },
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{ "Segment not present", SIGSEGV, 286 },
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{ "Stack exception", SIGSEGV, 286 }, /* STACK_FAULT already used */
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{ "General protection", SIGSEGV, 286 },
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{ "Page fault", SIGSEGV, 386 }, /* not close */
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{ NULL, SIGILL, 0 }, /* probably software trap */
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{ "Coprocessor error", SIGFPE, 386 },
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{ "Alignment check", SIGBUS, 386 },
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{ "Machine check", SIGBUS, 386 },
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{ "SIMD exception", SIGFPE, 386 },
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};
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static void inkernel_disaster(struct proc *saved_proc,
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struct exception_frame *frame, struct ex_s *ep, int is_nested);
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extern int catch_pagefaults;
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static void proc_stacktrace_execute(struct proc *whichproc, reg_t v_bp, reg_t pc);
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static void pagefault( struct proc *pr,
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struct exception_frame * frame,
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int is_nested)
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{
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int in_physcopy = 0, in_memset = 0;
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reg_t pagefaultcr2;
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message m_pagefault;
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int err;
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pagefaultcr2 = read_cr2();
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#if 0
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printf("kernel: pagefault in pr %d, addr 0x%lx, his cr3 0x%lx, actual cr3 0x%lx\n",
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pr->p_endpoint, pagefaultcr2, pr->p_seg.p_cr3, read_cr3());
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#endif
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in_physcopy = (frame->eip > (vir_bytes) phys_copy) &&
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(frame->eip < (vir_bytes) phys_copy_fault);
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in_memset = (frame->eip > (vir_bytes) phys_memset) &&
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(frame->eip < (vir_bytes) memset_fault);
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if((is_nested || iskernelp(pr)) &&
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catch_pagefaults && (in_physcopy || in_memset)) {
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#if 0
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printf("pf caught! addr 0x%lx\n", pagefaultcr2);
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#endif
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if (is_nested) {
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if(in_physcopy) {
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assert(!in_memset);
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frame->eip = (reg_t) phys_copy_fault_in_kernel;
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} else {
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frame->eip = (reg_t) memset_fault_in_kernel;
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}
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}
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else {
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pr->p_reg.pc = (reg_t) phys_copy_fault;
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pr->p_reg.retreg = pagefaultcr2;
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}
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return;
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}
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if(is_nested) {
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printf("pagefault in kernel at pc 0x%lx address 0x%lx\n",
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frame->eip, pagefaultcr2);
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inkernel_disaster(pr, frame, NULL, is_nested);
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}
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/* VM can't handle page faults. */
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if(pr->p_endpoint == VM_PROC_NR) {
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/* Page fault we can't / don't want to
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* handle.
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*/
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printf("pagefault for VM on CPU %d, "
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"pc = 0x%x, addr = 0x%x, flags = 0x%x, is_nested %d\n",
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cpuid, pr->p_reg.pc, pagefaultcr2, frame->errcode,
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is_nested);
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proc_stacktrace(pr);
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printf("pc of pagefault: 0x%lx\n", frame->eip);
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panic("pagefault in VM");
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return;
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}
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/* Don't schedule this process until pagefault is handled. */
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RTS_SET(pr, RTS_PAGEFAULT);
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/* tell Vm about the pagefault */
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m_pagefault.m_source = pr->p_endpoint;
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m_pagefault.m_type = VM_PAGEFAULT;
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m_pagefault.VPF_ADDR = pagefaultcr2;
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m_pagefault.VPF_FLAGS = frame->errcode;
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if ((err = mini_send(pr, VM_PROC_NR,
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&m_pagefault, FROM_KERNEL))) {
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panic("WARNING: pagefault: mini_send returned %d\n", err);
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}
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return;
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}
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static void inkernel_disaster(struct proc *saved_proc,
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struct exception_frame * frame, struct ex_s *ep,
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int is_nested)
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{
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#if USE_SYSDEBUG
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if(ep) {
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if (ep->msg == NULL)
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printf("\nIntel-reserved exception %d\n", frame->vector);
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else
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printf("\n%s\n", ep->msg);
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}
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printf("cpu %d is_nested = %d ", cpuid, is_nested);
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printf("vec_nr= %d, trap_errno= 0x%x, eip= 0x%x, "
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"cs= 0x%x, eflags= 0x%x trap_esp 0x%08x\n",
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frame->vector, frame->errcode, frame->eip,
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frame->cs, frame->eflags, frame);
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printf("KERNEL registers :\n");
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#define REG(n) (((u32_t *)frame)[-n])
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printf(
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"\t%%eax 0x%08x %%ebx 0x%08x %%ecx 0x%08x %%edx 0x%08x\n"
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"\t%%esp 0x%08x %%ebp 0x%08x %%esi 0x%08x %%edi 0x%08x\n",
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REG(1), REG(2), REG(3), REG(4),
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REG(5), REG(6), REG(7), REG(8));
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{
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reg_t k_ebp = REG(6);
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printf("KERNEL stacktrace, starting with ebp = 0x%lx:\n", k_ebp);
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proc_stacktrace_execute(proc_addr(SYSTEM), k_ebp, frame->eip);
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}
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if (saved_proc) {
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printf("scheduled was: process %d (%s), ", saved_proc->p_endpoint, saved_proc->p_name);
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printf("pc = 0x%x\n", (unsigned) saved_proc->p_reg.pc);
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proc_stacktrace(saved_proc);
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panic("Unhandled kernel exception");
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}
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/* in an early stage of boot process we don't have processes yet */
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panic("exception in kernel while booting, no saved_proc yet");
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#endif /* USE_SYSDEBUG */
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}
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/*===========================================================================*
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* exception *
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*===========================================================================*/
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void exception_handler(int is_nested, struct exception_frame * frame)
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{
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/* An exception or unexpected interrupt has occurred. */
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register struct ex_s *ep;
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struct proc *saved_proc;
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/* Save proc_ptr, because it may be changed by debug statements. */
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saved_proc = get_cpulocal_var(proc_ptr);
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ep = &ex_data[frame->vector];
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if (frame->vector == 2) { /* spurious NMI on some machines */
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printf("got spurious NMI\n");
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return;
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}
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/*
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* handle special cases for nested problems as they might be tricky or filter
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* them out quickly if the traps are not nested
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*/
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if (is_nested) {
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/*
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* if a problem occured while copying a message from userspace because
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* of a wrong pointer supplied by userland, handle it the only way we
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* can handle it ...
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*/
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if (((void*)frame->eip >= (void*)copy_msg_to_user &&
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(void*)frame->eip <= (void*)__copy_msg_to_user_end) ||
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((void*)frame->eip >= (void*)copy_msg_from_user &&
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(void*)frame->eip <= (void*)__copy_msg_from_user_end)) {
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switch(frame->vector) {
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/* these error are expected */
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case PAGE_FAULT_VECTOR:
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case PROTECTION_VECTOR:
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frame->eip = (reg_t) __user_copy_msg_pointer_failure;
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return;
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default:
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panic("Copy involving a user pointer failed unexpectedly!");
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}
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}
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/* Pass any error resulting from restoring FPU state, as a FPU
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* exception to the process.
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*/
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if (((void*)frame->eip >= (void*)fxrstor &&
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(void *)frame->eip <= (void*)__fxrstor_end) ||
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((void*)frame->eip >= (void*)frstor &&
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(void *)frame->eip <= (void*)__frstor_end)) {
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frame->eip = (reg_t) __frstor_failure;
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return;
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}
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if(frame->vector == DEBUG_VECTOR
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&& (saved_proc->p_reg.psw & TRACEBIT)
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&& (saved_proc->p_seg.p_kern_trap_style == KTS_NONE)) {
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/* Getting a debug trap in the kernel is legitimate
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* if a traced process entered the kernel using sysenter
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* or syscall; the trap flag is not cleared then.
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*
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* It triggers on the first kernel entry so the trap
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* style is still KTS_NONE.
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*/
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frame->eflags &= ~TRACEBIT;
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return;
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/* If control passes, this case is not recognized as legitimate
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* and we panic later on after all.
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*/
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}
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}
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if(frame->vector == PAGE_FAULT_VECTOR) {
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pagefault(saved_proc, frame, is_nested);
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return;
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}
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/* If an exception occurs while running a process, the is_nested variable
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* will be zero. Exceptions in interrupt handlers or system traps will make
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* is_nested non-zero.
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*/
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if (is_nested == 0 && ! iskernelp(saved_proc)) {
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#if 0
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{
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printf(
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"vec_nr= %d, trap_errno= 0x%lx, eip= 0x%lx, cs= 0x%x, eflags= 0x%lx\n",
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frame->vector, (unsigned long)frame->errcode,
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(unsigned long)frame->eip, frame->cs,
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(unsigned long)frame->eflags);
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proc_stacktrace(saved_proc);
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}
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#endif
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cause_sig(proc_nr(saved_proc), ep->signum);
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return;
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}
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/* Exception in system code. This is not supposed to happen. */
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inkernel_disaster(saved_proc, frame, ep, is_nested);
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panic("return from inkernel_disaster");
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}
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#if USE_SYSDEBUG
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/*===========================================================================*
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* proc_stacktrace_execute *
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*===========================================================================*/
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static void proc_stacktrace_execute(struct proc *whichproc, reg_t v_bp, reg_t pc)
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{
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reg_t v_hbp;
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int iskernel;
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int n = 0;
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iskernel = iskernelp(whichproc);
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printf("%-8.8s %6d 0x%lx ",
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whichproc->p_name, whichproc->p_endpoint, pc);
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while(v_bp) {
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reg_t v_pc;
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#define PRCOPY(pr, pv, v, n) \
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(iskernel ? (memcpy((char *) v, (char *) pv, n), OK) : \
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data_copy(pr->p_endpoint, pv, KERNEL, (vir_bytes) (v), n))
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if(PRCOPY(whichproc, v_bp, &v_hbp, sizeof(v_hbp)) != OK) {
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printf("(v_bp 0x%lx ?)", v_bp);
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break;
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}
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if(PRCOPY(whichproc, v_bp + sizeof(v_pc), &v_pc, sizeof(v_pc)) != OK) {
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printf("(v_pc 0x%lx ?)", v_bp + sizeof(v_pc));
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break;
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}
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printf("0x%lx ", (unsigned long) v_pc);
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if(v_hbp != 0 && v_hbp <= v_bp) {
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printf("(hbp %lx ?)", v_hbp);
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break;
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}
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v_bp = v_hbp;
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if(n++ > 50) {
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printf("(truncated after %d steps) ", n);
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break;
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}
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}
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printf("\n");
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}
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#endif /* USE_SYSDEBUG */
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/*===========================================================================*
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* proc_stacktrace *
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*===========================================================================*/
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void proc_stacktrace(struct proc *whichproc)
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{
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u32_t use_bp;
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if(whichproc->p_seg.p_kern_trap_style == KTS_NONE) {
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printf("WARNING: stacktrace of running proecss\n");
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}
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switch(whichproc->p_seg.p_kern_trap_style) {
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case KTS_SYSENTER:
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case KTS_SYSCALL:
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{
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u32_t sp = whichproc->p_reg.sp;
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/* Full context is not available in the p_reg
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* struct. Obtain it from the user's stack.
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* The use stack pointer is always available.
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* The fact that it's there, and the 16 byte offset,
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* is a dependency on the trap code in
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* kernel/arch/i386/usermapped_glo_ipc.S.
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*/
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if(data_copy(whichproc->p_endpoint, sp+16,
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KERNEL, (vir_bytes) &use_bp,
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sizeof(use_bp)) != OK) {
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printf("stacktrace: aborting, copy failed\n");
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return;
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}
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break;
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}
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default:
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/* Full context is available; use the stored ebp */
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use_bp = whichproc->p_reg.fp;
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break;
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}
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#if USE_SYSDEBUG
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proc_stacktrace_execute(whichproc, use_bp, whichproc->p_reg.pc);
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#endif /* USE_SYSDEBUG */
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}
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void enable_fpu_exception(void)
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{
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u32_t cr0 = read_cr0();
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if(!(cr0 & I386_CR0_TS))
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write_cr0(cr0 | I386_CR0_TS);
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}
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void disable_fpu_exception(void)
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{
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clts();
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}
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