traps.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 640 行 · 第 1/2 页

	unsigned long fpscr;

	flush_fp_to_thread(current);

	fpscr = current->thread.fpscr;

	/* Invalid operation */
	if ((fpscr & FPSCR_VE) && (fpscr & FPSCR_VX))
		code = FPE_FLTINV;

	/* Overflow */
	else if ((fpscr & FPSCR_OE) && (fpscr & FPSCR_OX))
		code = FPE_FLTOVF;

	/* Underflow */
	else if ((fpscr & FPSCR_UE) && (fpscr & FPSCR_UX))
		code = FPE_FLTUND;

	/* Divide by zero */
	else if ((fpscr & FPSCR_ZE) && (fpscr & FPSCR_ZX))
		code = FPE_FLTDIV;

	/* Inexact result */
	else if ((fpscr & FPSCR_XE) && (fpscr & FPSCR_XX))
		code = FPE_FLTRES;

	_exception(SIGFPE, regs, code, regs->nip);
}

/*
 * Illegal instruction emulation support.  Return non-zero if we can't
 * emulate, or -EFAULT if the associated memory access caused an access
 * fault.  Return zero on success.
 */

#define INST_DCBA		0x7c0005ec
#define INST_DCBA_MASK		0x7c0007fe

#define INST_MCRXR		0x7c000400
#define INST_MCRXR_MASK		0x7c0007fe

static int emulate_instruction(struct pt_regs *regs)
{
	unsigned int instword;

	if (!user_mode(regs))
		return -EINVAL;

	CHECK_FULL_REGS(regs);

	if (get_user(instword, (unsigned int __user *)(regs->nip)))
		return -EFAULT;

	/* Emulating the dcba insn is just a no-op.  */
	if ((instword & INST_DCBA_MASK) == INST_DCBA) {
		static int warned;

		if (!warned) {
			printk(KERN_WARNING
			       "process %d (%s) uses obsolete 'dcba' insn\n",
			       current->pid, current->comm);
			warned = 1;
		}
		return 0;
	}

	/* Emulate the mcrxr insn.  */
	if ((instword & INST_MCRXR_MASK) == INST_MCRXR) {
		static int warned;
		unsigned int shift;

		if (!warned) {
			printk(KERN_WARNING
			       "process %d (%s) uses obsolete 'mcrxr' insn\n",
			       current->pid, current->comm);
			warned = 1;
		}

		shift = (instword >> 21) & 0x1c;
		regs->ccr &= ~(0xf0000000 >> shift);
		regs->ccr |= (regs->xer & 0xf0000000) >> shift;
		regs->xer &= ~0xf0000000;
		return 0;
	}

	return -EINVAL;
}

/*
 * Look through the list of trap instructions that are used for BUG(),
 * BUG_ON() and WARN_ON() and see if we hit one.  At this point we know
 * that the exception was caused by a trap instruction of some kind.
 * Returns 1 if we should continue (i.e. it was a WARN_ON) or 0
 * otherwise.
 */
extern struct bug_entry __start___bug_table[], __stop___bug_table[];

#ifndef CONFIG_MODULES
#define module_find_bug(x)	NULL
#endif

static struct bug_entry *find_bug(unsigned long bugaddr)
{
	struct bug_entry *bug;

	for (bug = __start___bug_table; bug < __stop___bug_table; ++bug)
		if (bugaddr == bug->bug_addr)
			return bug;
	return module_find_bug(bugaddr);
}

int
check_bug_trap(struct pt_regs *regs)
{
	struct bug_entry *bug;
	unsigned long addr;

	if (regs->msr & MSR_PR)
		return 0;	/* not in kernel */
	addr = regs->nip;	/* address of trap instruction */
	if (addr < PAGE_OFFSET)
		return 0;
	bug = find_bug(regs->nip);
	if (bug == NULL)
		return 0;
	if (bug->line & BUG_WARNING_TRAP) {
		/* this is a WARN_ON rather than BUG/BUG_ON */
		printk(KERN_ERR "Badness in %s at %s:%d\n",
		       bug->function, bug->file,
		      (unsigned int)bug->line & ~BUG_WARNING_TRAP);
		show_stack(current, (void *)regs->gpr[1]);
		return 1;
	}
	printk(KERN_CRIT "kernel BUG in %s at %s:%d!\n",
	       bug->function, bug->file, (unsigned int)bug->line);
	return 0;
}

void
ProgramCheckException(struct pt_regs *regs)
{
	if (regs->msr & 0x100000) {
		/* IEEE FP exception */
		parse_fpe(regs);

	} else if (regs->msr & 0x40000) {
		/* Privileged instruction */
		_exception(SIGILL, regs, ILL_PRVOPC, regs->nip);

	} else if (regs->msr & 0x20000) {
		/* trap exception */

		if (debugger_bpt(regs))
			return;

		if (check_bug_trap(regs)) {
			regs->nip += 4;
			return;
		}
		_exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip);

	} else {
		/* Illegal instruction; try to emulate it.  */
		switch (emulate_instruction(regs)) {
		case 0:
			regs->nip += 4;
			emulate_single_step(regs);
			break;

		case -EFAULT:
			_exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);
			break;

		default:
			_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
			break;
		}
	}
}

void KernelFPUnavailableException(struct pt_regs *regs)
{
	printk(KERN_EMERG "Unrecoverable FP Unavailable Exception "
			  "%lx at %lx\n", regs->trap, regs->nip);
	die("Unrecoverable FP Unavailable Exception", regs, SIGABRT);
}

void AltivecUnavailableException(struct pt_regs *regs)
{
#ifndef CONFIG_ALTIVEC
	if (user_mode(regs)) {
		/* A user program has executed an altivec instruction,
		   but this kernel doesn't support altivec. */
		_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
		return;
	}
#endif
	printk(KERN_EMERG "Unrecoverable VMX/Altivec Unavailable Exception "
			  "%lx at %lx\n", regs->trap, regs->nip);
	die("Unrecoverable VMX/Altivec Unavailable Exception", regs, SIGABRT);
}

/* Ensure exceptions are disabled */
#define MMCR0_PMXE      (1UL << (31 - 5))
#define MMCR0_PMAO      (1UL << (31 - 24))

static void dummy_perf(struct pt_regs *regs)
{
	unsigned int mmcr0 = mfspr(SPRN_MMCR0);

	mmcr0 &= ~(MMCR0_PMXE|MMCR0_PMAO);
	mtspr(SPRN_MMCR0, mmcr0);
}

void (*perf_irq)(struct pt_regs *) = dummy_perf;

EXPORT_SYMBOL(perf_irq);

void
PerformanceMonitorException(struct pt_regs *regs)
{
	perf_irq(regs);
}

void
AlignmentException(struct pt_regs *regs)
{
	int fixed;

	fixed = fix_alignment(regs);

	if (fixed == 1) {
		regs->nip += 4;	/* skip over emulated instruction */
		emulate_single_step(regs);
		return;
	}

	/* Operand address was bad */	
	if (fixed == -EFAULT) {
		if (user_mode(regs)) {
			_exception(SIGSEGV, regs, SEGV_MAPERR, regs->dar);
		} else {
			/* Search exception table */
			bad_page_fault(regs, regs->dar, SIGSEGV);
		}

		return;
	}

	_exception(SIGBUS, regs, BUS_ADRALN, regs->nip);
}

#ifdef CONFIG_ALTIVEC
void
AltivecAssistException(struct pt_regs *regs)
{
	int err;
	siginfo_t info;

	if (!user_mode(regs)) {
		printk(KERN_EMERG "VMX/Altivec assist exception in kernel mode"
		       " at %lx\n", regs->nip);
		die("Kernel VMX/Altivec assist exception", regs, SIGILL);
	}

	flush_altivec_to_thread(current);

	err = emulate_altivec(regs);
	if (err == 0) {
		regs->nip += 4;		/* skip emulated instruction */
		emulate_single_step(regs);
		return;
	}

	if (err == -EFAULT) {
		/* got an error reading the instruction */
		info.si_signo = SIGSEGV;
		info.si_errno = 0;
		info.si_code = SEGV_MAPERR;
		info.si_addr = (void __user *) regs->nip;
		force_sig_info(SIGSEGV, &info, current);
	} else {
		/* didn't recognize the instruction */
		/* XXX quick hack for now: set the non-Java bit in the VSCR */
		if (printk_ratelimit())
			printk(KERN_ERR "Unrecognized altivec instruction "
			       "in %s at %lx\n", current->comm, regs->nip);
		current->thread.vscr.u[3] |= 0x10000;
	}
}
#endif /* CONFIG_ALTIVEC */

/*
 * We enter here if we get an unrecoverable exception, that is, one
 * that happened at a point where the RI (recoverable interrupt) bit
 * in the MSR is 0.  This indicates that SRR0/1 are live, and that
 * we therefore lost state by taking this exception.
 */
void unrecoverable_exception(struct pt_regs *regs)
{
	printk(KERN_EMERG "Unrecoverable exception %lx at %lx\n",
	       regs->trap, regs->nip);
	die("Unrecoverable exception", regs, SIGABRT);
}

/*
 * We enter here if we discover during exception entry that we are
 * running in supervisor mode with a userspace value in the stack pointer.
 */
void kernel_bad_stack(struct pt_regs *regs)
{
	printk(KERN_EMERG "Bad kernel stack pointer %lx at %lx\n",
	       regs->gpr[1], regs->nip);
	die("Bad kernel stack pointer", regs, SIGABRT);
}

void __init trap_init(void)
{
}