traps.c

MIZI Research, Inc.发布的嵌入式Linux内核源码

		"	.gprel32 4b\n"
		"	lda $31,5b-4b(%0)\n"
		".previous"
			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2),
			  "=&r"(tmp3), "=&r"(tmp4)
			: "r"(va), "r"(una_reg(reg)), "0"(0));
		if (error)
			goto got_exception;
		return;

	case 0x2d: /* stq */
		__asm__ __volatile__(
		"1:	ldq_u %2,7(%5)\n"
		"2:	ldq_u %1,0(%5)\n"
		"	insqh %6,%5,%4\n"
		"	insql %6,%5,%3\n"
		"	mskqh %2,%5,%2\n"
		"	mskql %1,%5,%1\n"
		"	or %2,%4,%2\n"
		"	or %1,%3,%1\n"
		"3:	stq_u %2,7(%5)\n"
		"4:	stq_u %1,0(%5)\n"
		"5:\n"
		".section __ex_table,\"a\"\n\t"
		"	.gprel32 1b\n"
		"	lda %2,5b-1b(%0)\n"
		"	.gprel32 2b\n"
		"	lda %1,5b-2b(%0)\n"
		"	.gprel32 3b\n"
		"	lda $31,5b-3b(%0)\n"
		"	.gprel32 4b\n"
		"	lda $31,5b-4b(%0)\n"
		".previous"
			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2),
			  "=&r"(tmp3), "=&r"(tmp4)
			: "r"(va), "r"(una_reg(reg)), "0"(0));
		if (error)
			goto got_exception;
		return;
	}

	lock_kernel();
	printk("Bad unaligned kernel access at %016lx: %p %lx %ld\n",
		pc, va, opcode, reg);
	do_exit(SIGSEGV);

got_exception:
	/* Ok, we caught the exception, but we don't want it.  Is there
	   someone to pass it along to?  */
	if ((fixup = search_exception_table(pc, regs.gp)) != 0) {
		unsigned long newpc;
		newpc = fixup_exception(una_reg, fixup, pc);

		printk("Forwarding unaligned exception at %lx (%lx)\n",
		       pc, newpc);

		(&regs)->pc = newpc;
		return;
	}

	/*
	 * Yikes!  No one to forward the exception to.
	 * Since the registers are in a weird format, dump them ourselves.
 	 */
	lock_kernel();

	printk("%s(%d): unhandled unaligned exception\n",
	       current->comm, current->pid);

	printk("pc = [<%016lx>]  ra = [<%016lx>]  ps = %04lx\n",
	       pc, una_reg(26), regs.ps);
	printk("r0 = %016lx  r1 = %016lx  r2 = %016lx\n",
	       una_reg(0), una_reg(1), una_reg(2));
	printk("r3 = %016lx  r4 = %016lx  r5 = %016lx\n",
 	       una_reg(3), una_reg(4), una_reg(5));
	printk("r6 = %016lx  r7 = %016lx  r8 = %016lx\n",
	       una_reg(6), una_reg(7), una_reg(8));
	printk("r9 = %016lx  r10= %016lx  r11= %016lx\n",
	       una_reg(9), una_reg(10), una_reg(11));
	printk("r12= %016lx  r13= %016lx  r14= %016lx\n",
	       una_reg(12), una_reg(13), una_reg(14));
	printk("r15= %016lx\n", una_reg(15));
	printk("r16= %016lx  r17= %016lx  r18= %016lx\n",
	       una_reg(16), una_reg(17), una_reg(18));
	printk("r19= %016lx  r20= %016lx  r21= %016lx\n",
 	       una_reg(19), una_reg(20), una_reg(21));
 	printk("r22= %016lx  r23= %016lx  r24= %016lx\n",
	       una_reg(22), una_reg(23), una_reg(24));
	printk("r25= %016lx  r27= %016lx  r28= %016lx\n",
	       una_reg(25), una_reg(27), una_reg(28));
	printk("gp = %016lx  sp = %p\n", regs.gp, &regs+1);

	dik_show_code((unsigned int *)pc);
	dik_show_trace((unsigned long *)(&regs+1));

	if (current->thread.flags & (1UL << 63)) {
		printk("die_if_kernel recursion detected.\n");
		sti();
		while (1);
	}
	current->thread.flags |= (1UL << 63);
	do_exit(SIGSEGV);
}

/*
 * Convert an s-floating point value in memory format to the
 * corresponding value in register format.  The exponent
 * needs to be remapped to preserve non-finite values
 * (infinities, not-a-numbers, denormals).
 */
static inline unsigned long
s_mem_to_reg (unsigned long s_mem)
{
	unsigned long frac    = (s_mem >>  0) & 0x7fffff;
	unsigned long sign    = (s_mem >> 31) & 0x1;
	unsigned long exp_msb = (s_mem >> 30) & 0x1;
	unsigned long exp_low = (s_mem >> 23) & 0x7f;
	unsigned long exp;

	exp = (exp_msb << 10) | exp_low;	/* common case */
	if (exp_msb) {
		if (exp_low == 0x7f) {
			exp = 0x7ff;
		}
	} else {
		if (exp_low == 0x00) {
			exp = 0x000;
		} else {
			exp |= (0x7 << 7);
		}
	}
	return (sign << 63) | (exp << 52) | (frac << 29);
}

/*
 * Convert an s-floating point value in register format to the
 * corresponding value in memory format.
 */
static inline unsigned long
s_reg_to_mem (unsigned long s_reg)
{
	return ((s_reg >> 62) << 30) | ((s_reg << 5) >> 34);
}

/*
 * Handle user-level unaligned fault.  Handling user-level unaligned
 * faults is *extremely* slow and produces nasty messages.  A user
 * program *should* fix unaligned faults ASAP.
 *
 * Notice that we have (almost) the regular kernel stack layout here,
 * so finding the appropriate registers is a little more difficult
 * than in the kernel case.
 *
 * Finally, we handle regular integer load/stores only.  In
 * particular, load-linked/store-conditionally and floating point
 * load/stores are not supported.  The former make no sense with
 * unaligned faults (they are guaranteed to fail) and I don't think
 * the latter will occur in any decent program.
 *
 * Sigh. We *do* have to handle some FP operations, because GCC will
 * uses them as temporary storage for integer memory to memory copies.
 * However, we need to deal with stt/ldt and sts/lds only.
 */

#define OP_INT_MASK	( 1L << 0x28 | 1L << 0x2c   /* ldl stl */	\
			| 1L << 0x29 | 1L << 0x2d   /* ldq stq */	\
			| 1L << 0x0c | 1L << 0x0d   /* ldwu stw */	\
			| 1L << 0x0a | 1L << 0x0e ) /* ldbu stb */

#define OP_WRITE_MASK	( 1L << 0x26 | 1L << 0x27   /* sts stt */	\
			| 1L << 0x2c | 1L << 0x2d   /* stl stq */	\
			| 1L << 0x0d | 1L << 0x0e ) /* stw stb */

#define R(x)	((size_t) &((struct pt_regs *)0)->x)

static int unauser_reg_offsets[32] = {
	R(r0), R(r1), R(r2), R(r3), R(r4), R(r5), R(r6), R(r7), R(r8),
	/* r9 ... r15 are stored in front of regs.  */
	-56, -48, -40, -32, -24, -16, -8,
	R(r16), R(r17), R(r18),
	R(r19), R(r20), R(r21), R(r22), R(r23), R(r24), R(r25), R(r26),
	R(r27), R(r28), R(gp),
	0, 0
};

#undef R

asmlinkage void
do_entUnaUser(void * va, unsigned long opcode,
	      unsigned long reg, struct pt_regs *regs)
{
	static int cnt = 0;
	static long last_time = 0;

	unsigned long tmp1, tmp2, tmp3, tmp4;
	unsigned long fake_reg, *reg_addr = &fake_reg;
	unsigned long uac_bits;
	long error;

	/* Check the UAC bits to decide what the user wants us to do
	   with the unaliged access.  */

	uac_bits = (current->thread.flags >> UAC_SHIFT) & UAC_BITMASK;
	if (!(uac_bits & UAC_NOPRINT)) {
		if (cnt >= 5 && jiffies - last_time > 5*HZ) {
			cnt = 0;
		}
		if (++cnt < 5) {
			printk("%s(%d): unaligned trap at %016lx: %p %lx %ld\n",
			       current->comm, current->pid,
			       regs->pc - 4, va, opcode, reg);
		}
		last_time = jiffies;
	}
	if (uac_bits & UAC_SIGBUS) {
		goto give_sigbus;
	}
	if (uac_bits & UAC_NOFIX) {
		/* Not sure why you'd want to use this, but... */
		return;
	}

	/* Don't bother reading ds in the access check since we already
	   know that this came from the user.  Also rely on the fact that
	   the page at TASK_SIZE is unmapped and so can't be touched anyway. */
	if (!__access_ok((unsigned long)va, 0, USER_DS))
		goto give_sigsegv;

	++unaligned[1].count;
	unaligned[1].va = (unsigned long)va;
	unaligned[1].pc = regs->pc - 4;

	if ((1L << opcode) & OP_INT_MASK) {
		/* it's an integer load/store */
		if (reg < 30) {
			reg_addr = (unsigned long *)
			  ((char *)regs + unauser_reg_offsets[reg]);
		} else if (reg == 30) {
			/* usp in PAL regs */
			fake_reg = rdusp();
		} else {
			/* zero "register" */
			fake_reg = 0;
		}
	}

	/* We don't want to use the generic get/put unaligned macros as
	   we want to trap exceptions.  Only if we actually get an
	   exception will we decide whether we should have caught it.  */

	switch (opcode) {
	case 0x0c: /* ldwu */
		__asm__ __volatile__(
		"1:	ldq_u %1,0(%3)\n"
		"2:	ldq_u %2,1(%3)\n"
		"	extwl %1,%3,%1\n"
		"	extwh %2,%3,%2\n"
		"3:\n"
		".section __ex_table,\"a\"\n"
		"	.gprel32 1b\n"
		"	lda %1,3b-1b(%0)\n"
		"	.gprel32 2b\n"
		"	lda %2,3b-2b(%0)\n"
		".previous"
			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2)
			: "r"(va), "0"(0));
		if (error)
			goto give_sigsegv;
		*reg_addr = tmp1|tmp2;
		break;

	case 0x22: /* lds */
		__asm__ __volatile__(
		"1:	ldq_u %1,0(%3)\n"
		"2:	ldq_u %2,3(%3)\n"
		"	extll %1,%3,%1\n"
		"	extlh %2,%3,%2\n"
		"3:\n"
		".section __ex_table,\"a\"\n"
		"	.gprel32 1b\n"
		"	lda %1,3b-1b(%0)\n"
		"	.gprel32 2b\n"
		"	lda %2,3b-2b(%0)\n"
		".previous"
			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2)
			: "r"(va), "0"(0));
		if (error)
			goto give_sigsegv;
		alpha_write_fp_reg(reg, s_mem_to_reg((int)(tmp1|tmp2)));
		return;

	case 0x23: /* ldt */
		__asm__ __volatile__(
		"1:	ldq_u %1,0(%3)\n"
		"2:	ldq_u %2,7(%3)\n"
		"	extql %1,%3,%1\n"
		"	extqh %2,%3,%2\n"
		"3:\n"
		".section __ex_table,\"a\"\n"
		"	.gprel32 1b\n"
		"	lda %1,3b-1b(%0)\n"
		"	.gprel32 2b\n"
		"	lda %2,3b-2b(%0)\n"
		".previous"
			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2)
			: "r"(va), "0"(0));
		if (error)
			goto give_sigsegv;
		alpha_write_fp_reg(reg, tmp1|tmp2);
		return;

	case 0x28: /* ldl */
		__asm__ __volatile__(
		"1:	ldq_u %1,0(%3)\n"
		"2:	ldq_u %2,3(%3)\n"
		"	extll %1,%3,%1\n"
		"	extlh %2,%3,%2\n"
		"3:\n"
		".section __ex_table,\"a\"\n"
		"	.gprel32 1b\n"
		"	lda %1,3b-1b(%0)\n"
		"	.gprel32 2b\n"
		"	lda %2,3b-2b(%0)\n"
		".previous"
			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2)
			: "r"(va), "0"(0));
		if (error)
			goto give_sigsegv;
		*reg_addr = (int)(tmp1|tmp2);
		break;

	case 0x29: /* ldq */
		__asm__ __volatile__(
		"1:	ldq_u %1,0(%3)\n"
		"2:	ldq_u %2,7(%3)\n"
		"	extql %1,%3,%1\n"
		"	extqh %2,%3,%2\n"
		"3:\n"
		".section __ex_table,\"a\"\n"
		"	.gprel32 1b\n"
		"	lda %1,3b-1b(%0)\n"
		"	.gprel32 2b\n"
		"	lda %2,3b-2b(%0)\n"
		".previous"
			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2)
			: "r"(va), "0"(0));
		if (error)
			goto give_sigsegv;
		*reg_addr = tmp1|tmp2;
		break;

	/* Note that the store sequences do not indicate that they change
	   memory because it _should_ be affecting nothing in this context.
	   (Otherwise we have other, much larger, problems.)  */
	case 0x0d: /* stw */
		__asm__ __volatile__(
		"1:	ldq_u %2,1(%5)\n"
		"2:	ldq_u %1,0(%5)\n"
		"	inswh %6,%5,%4\n"
		"	inswl %6,%5,%3\n"
		"	mskwh %2,%5,%2\n"
		"	mskwl %1,%5,%1\n"
		"	or %2,%4,%2\n"
		"	or %1,%3,%1\n"
		"3:	stq_u %2,1(%5)\n"
		"4:	stq_u %1,0(%5)\n"
		"5:\n"
		".section __ex_table,\"a\"\n"
		"	.gprel32 1b\n"
		"	lda %2,5b-1b(%0)\n"
		"	.gprel32 2b\n"
		"	lda %1,5b-2b(%0)\n"
		"	.gprel32 3b\n"
		"	lda $31,5b-3b(%0)\n"
		"	.gprel32 4b\n"
		"	lda $31,5b-4b(%0)\n"
		".previous"
			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2),
			  "=&r"(tmp3), "=&r"(tmp4)
			: "r"(va), "r"(*reg_addr), "0"(0));
		if (error)
			goto give_sigsegv;
		return;

	case 0x26: /* sts */
		fake_reg = s_reg_to_mem(alpha_read_fp_reg(reg));
		/* FALLTHRU */

	case 0x2c: /* stl */
		__asm__ __volatile__(
		"1:	ldq_u %2,3(%5)\n"
		"2:	ldq_u %1,0(%5)\n"
		"	inslh %6,%5,%4\n"
		"	insll %6,%5,%3\n"
		"	msklh %2,%5,%2\n"
		"	mskll %1,%5,%1\n"
		"	or %2,%4,%2\n"
		"	or %1,%3,%1\n"
		"3:	stq_u %2,3(%5)\n"
		"4:	stq_u %1,0(%5)\n"
		"5:\n"
		".section __ex_table,\"a\"\n"
		"	.gprel32 1b\n"
		"	lda %2,5b-1b(%0)\n"
		"	.gprel32 2b\n"
		"	lda %1,5b-2b(%0)\n"
		"	.gprel32 3b\n"
		"	lda $31,5b-3b(%0)\n"
		"	.gprel32 4b\n"
		"	lda $31,5b-4b(%0)\n"
		".previous"
			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2),
			  "=&r"(tmp3), "=&r"(tmp4)
			: "r"(va), "r"(*reg_addr), "0"(0));
		if (error)
			goto give_sigsegv;
		return;

	case 0x27: /* stt */
		fake_reg = alpha_read_fp_reg(reg);
		/* FALLTHRU */

	case 0x2d: /* stq */
		__asm__ __volatile__(
		"1:	ldq_u %2,7(%5)\n"
		"2:	ldq_u %1,0(%5)\n"
		"	insqh %6,%5,%4\n"
		"	insql %6,%5,%3\n"
		"	mskqh %2,%5,%2\n"
		"	mskql %1,%5,%1\n"
		"	or %2,%4,%2\n"
		"	or %1,%3,%1\n"
		"3:	stq_u %2,7(%5)\n"
		"4:	stq_u %1,0(%5)\n"
		"5:\n"
		".section __ex_table,\"a\"\n\t"
		"	.gprel32 1b\n"
		"	lda %2,5b-1b(%0)\n"
		"	.gprel32 2b\n"
		"	lda %1,5b-2b(%0)\n"
		"	.gprel32 3b\n"
		"	lda $31,5b-3b(%0)\n"
		"	.gprel32 4b\n"
		"	lda $31,5b-4b(%0)\n"
		".previous"
			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2),
			  "=&r"(tmp3), "=&r"(tmp4)
			: "r"(va), "r"(*reg_addr), "0"(0));
		if (error)
			goto give_sigsegv;
		return;

	default:
		/* What instruction were you trying to use, exactly?  */
		goto give_sigbus;
	}

	/* Only integer loads should get here; everyone else returns early. */
	if (reg == 30)
		wrusp(fake_reg);
	return;

give_sigsegv:
	regs->pc -= 4;  /* make pc point to faulting insn */
	send_sig(SIGSEGV, current, 1);
	return;

give_sigbus:
	regs->pc -= 4;
	send_sig(SIGBUS, current, 1);
	return;
}

/*
 * Unimplemented system calls.
 */
asmlinkage long
alpha_ni_syscall(unsigned long a0, unsigned long a1, unsigned long a2,
		 unsigned long a3, unsigned long a4, unsigned long a5,
		 struct pt_regs regs)
{
	/* We only get here for OSF system calls, minus #112;
	   the rest go to sys_ni_syscall.  */
#if 0
	printk("<sc %ld(%lx,%lx,%lx)>", regs.r0, a0, a1, a2);
#endif
	return -ENOSYS;
}

void
trap_init(void)
{
	/* Tell PAL-code what global pointer we want in the kernel.  */
	register unsigned long gptr __asm__("$29");
	wrkgp(gptr);

	wrent(entArith, 1);
	wrent(entMM, 2);
	wrent(entIF, 3);
	wrent(entUna, 4);
	wrent(entSys, 5);
	wrent(entDbg, 6);

	/* Hack for Multia (UDB) and JENSEN: some of their SRMs have
	 * a bug in the handling of the opDEC fault.  Fix it up if so.
	 */
	if (implver() == IMPLVER_EV4) {
		opDEC_check();
	}
}