295 lines
8.2 KiB
C
295 lines
8.2 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 "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 "kernel/proc.h"
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#include "kernel/proto.h"
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#include <machine/vm.h>
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extern int catch_pagefaults;
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PRIVATE 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;
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reg_t pagefaultcr2;
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message m_pagefault;
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int err;
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assert(frame);
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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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if(pr->p_seg.p_cr3) {
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assert(pr->p_seg.p_cr3 == read_cr3());
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}
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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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if((is_nested || iskernelp(pr)) &&
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catch_pagefaults && in_physcopy) {
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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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frame->eip = (reg_t) phys_copy_fault_in_kernel;
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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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panic("pagefault in kernel at pc 0x%lx address 0x%lx", frame->eip, pagefaultcr2);
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}
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/* System processes that don't have their own page table can't
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* have page faults. VM does have its own page table but also
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* can't have page faults (because VM has to handle them).
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*/
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if((pr->p_endpoint <= INIT_PROC_NR &&
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!(pr->p_misc_flags & MF_FULLVM)) || 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 process %d ('%s'), pc = 0x%x, addr = 0x%x, flags = 0x%x, is_nested %d\n",
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pr->p_endpoint, pr->p_name, pr->p_reg.pc,
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pagefaultcr2, frame->errcode, 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("page fault in system process: %d", pr->p_endpoint);
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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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assert(pr->p_seg.p_cr3 == read_cr3());
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assert(!RTS_ISSET(pr, RTS_PAGEFAULT));
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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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/*===========================================================================*
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* exception *
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*===========================================================================*/
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PUBLIC 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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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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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 = 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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}
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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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printseg("cs: ", 1, saved_proc, frame->cs);
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printseg("ds: ", 0, saved_proc, saved_proc->p_reg.ds);
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if(saved_proc->p_reg.ds != saved_proc->p_reg.ss) {
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printseg("ss: ", 0, saved_proc, saved_proc->p_reg.ss);
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}
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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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if (ep->msg == NULL || machine.processor < ep->minprocessor)
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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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printf("is_nested = %d ", 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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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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((u32_t *)frame)[-1],
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((u32_t *)frame)[-2],
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((u32_t *)frame)[-3],
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((u32_t *)frame)[-4],
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((u32_t *)frame)[-5],
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((u32_t *)frame)[-6],
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((u32_t *)frame)[-7],
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((u32_t *)frame)[-8]
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);
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printseg("ker cs: ", 1, NULL, frame->cs);
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printseg("ker ds: ", 0, NULL, DS_SELECTOR);
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/* TODO should we enable this only when compiled for some debug mode? */
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if (saved_proc) {
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printf("scheduled was: process %d (%s), ", proc_nr(saved_proc), saved_proc->p_name);
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printf("pc = %u:0x%x\n", (unsigned) saved_proc->p_reg.cs,
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(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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else {
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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");
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}
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}
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/*===========================================================================*
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* stacktrace *
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*===========================================================================*/
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PUBLIC void proc_stacktrace(struct proc *whichproc)
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{
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reg_t v_bp, v_pc, v_hbp;
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int iskernel;
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v_bp = whichproc->p_reg.fp;
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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, whichproc->p_reg.pc);
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while(v_bp) {
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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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}
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printf("\n");
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}
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PUBLIC void enable_fpu_exception(void)
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{
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write_cr0(read_cr0() | I386_CR0_TS);
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}
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PUBLIC void disable_fpu_exception(void)
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{
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clts();
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}
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