minix/kernel/arch/i386/exception.c
Ben Gras 604046faf3 kernel: trap-dependent state restore, trace fixes
. 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
2013-01-08 15:47:37 +00:00

386 lines
10 KiB
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 %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 proecss\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();
}