unwind.c

xen虚拟机源代码安装包

	if (regnum <= 5) {
		addr = *(&info->f2_loc + (regnum - 2));
		if (!addr)
			addr = &info->sw->f2 + (regnum - 2);
	} else if (regnum <= 15) {
		if (regnum <= 11) {
			pt = get_scratch_regs(info);
			//XXX struct ia64_fpreg and struct pt_fpreg are same.
			addr = (struct ia64_fpreg*)(&pt->f6  + (regnum - 6));
		}
		else
			addr = &info->sw->f12 + (regnum - 12);
	} else if (regnum <= 31) {
		addr = info->fr_loc[regnum - 16];
		if (!addr)
			addr = &info->sw->f16 + (regnum - 16);
	} else {
		struct task_struct *t = info->task;

		if (write)
			ia64_sync_fph(t);
		else
			ia64_flush_fph(t);
#ifdef XEN
		addr = t->arch._thread.fph + (regnum - 32);
#else
		addr = t->thread.fph + (regnum - 32);
#endif
	}

	if (write)
		if (read_only(addr)) {
			UNW_DPRINT(0, "unwind.%s: ignoring attempt to write read-only location\n",
				__FUNCTION__);
		} else
			*addr = *val;
	else
		*val = *addr;
	return 0;
}
EXPORT_SYMBOL(unw_access_fr);

int
unw_access_ar (struct unw_frame_info *info, int regnum, unsigned long *val, int write)
{
	unsigned long *addr;
	struct pt_regs *pt;

	switch (regnum) {
	      case UNW_AR_BSP:
		addr = info->bsp_loc;
		if (!addr)
			addr = &info->sw->ar_bspstore;
		break;

	      case UNW_AR_BSPSTORE:
		addr = info->bspstore_loc;
		if (!addr)
			addr = &info->sw->ar_bspstore;
		break;

	      case UNW_AR_PFS:
		addr = info->pfs_loc;
		if (!addr)
			addr = &info->sw->ar_pfs;
		break;

	      case UNW_AR_RNAT:
		addr = info->rnat_loc;
		if (!addr)
			addr = &info->sw->ar_rnat;
		break;

	      case UNW_AR_UNAT:
		addr = info->unat_loc;
		if (!addr)
			addr = &info->sw->caller_unat;
		break;

	      case UNW_AR_LC:
		addr = info->lc_loc;
		if (!addr)
			addr = &info->sw->ar_lc;
		break;

	      case UNW_AR_EC:
		if (!info->cfm_loc)
			return -1;
		if (write)
			*info->cfm_loc =
				(*info->cfm_loc & ~(0x3fUL << 52)) | ((*val & 0x3f) << 52);
		else
			*val = (*info->cfm_loc >> 52) & 0x3f;
		return 0;

	      case UNW_AR_FPSR:
		addr = info->fpsr_loc;
		if (!addr)
			addr = &info->sw->ar_fpsr;
		break;

	      case UNW_AR_RSC:
		pt = get_scratch_regs(info);
		addr = &pt->ar_rsc;
		break;

	      case UNW_AR_CCV:
		pt = get_scratch_regs(info);
		addr = &pt->ar_ccv;
		break;

	      case UNW_AR_CSD:
		pt = get_scratch_regs(info);
		addr = &pt->ar_csd;
		break;

	      case UNW_AR_SSD:
		pt = get_scratch_regs(info);
		addr = &pt->ar_ssd;
		break;

	      default:
		UNW_DPRINT(0, "unwind.%s: trying to access non-existent ar%u\n",
			   __FUNCTION__, regnum);
		return -1;
	}

	if (write) {
		if (read_only(addr)) {
			UNW_DPRINT(0, "unwind.%s: ignoring attempt to write read-only location\n",
				__FUNCTION__);
		} else
			*addr = *val;
	} else
		*val = *addr;
	return 0;
}
EXPORT_SYMBOL(unw_access_ar);

int
unw_access_pr (struct unw_frame_info *info, unsigned long *val, int write)
{
	unsigned long *addr;

	addr = info->pr_loc;
	if (!addr)
		addr = &info->sw->pr;

	if (write) {
		if (read_only(addr)) {
			UNW_DPRINT(0, "unwind.%s: ignoring attempt to write read-only location\n",
				__FUNCTION__);
		} else
			*addr = *val;
	} else
		*val = *addr;
	return 0;
}
EXPORT_SYMBOL(unw_access_pr);


/* Routines to manipulate the state stack.  */

static inline void
push (struct unw_state_record *sr)
{
	struct unw_reg_state *rs;

	rs = alloc_reg_state();
	if (!rs) {
		printk(KERN_ERR "unwind: cannot stack reg state!\n");
		return;
	}
	memcpy(rs, &sr->curr, sizeof(*rs));
	sr->curr.next = rs;
}

static void
pop (struct unw_state_record *sr)
{
	struct unw_reg_state *rs = sr->curr.next;

	if (!rs) {
		printk(KERN_ERR "unwind: stack underflow!\n");
		return;
	}
	memcpy(&sr->curr, rs, sizeof(*rs));
	free_reg_state(rs);
}

/* Make a copy of the state stack.  Non-recursive to avoid stack overflows.  */
static struct unw_reg_state *
dup_state_stack (struct unw_reg_state *rs)
{
	struct unw_reg_state *copy, *prev = NULL, *first = NULL;

	while (rs) {
		copy = alloc_reg_state();
		if (!copy) {
			printk(KERN_ERR "unwind.dup_state_stack: out of memory\n");
			return NULL;
		}
		memcpy(copy, rs, sizeof(*copy));
		if (first)
			prev->next = copy;
		else
			first = copy;
		rs = rs->next;
		prev = copy;
	}
	return first;
}

/* Free all stacked register states (but not RS itself).  */
static void
free_state_stack (struct unw_reg_state *rs)
{
	struct unw_reg_state *p, *next;

	for (p = rs->next; p != NULL; p = next) {
		next = p->next;
		free_reg_state(p);
	}
	rs->next = NULL;
}

/* Unwind decoder routines */

static enum unw_register_index __attribute_const__
decode_abreg (unsigned char abreg, int memory)
{
	switch (abreg) {
	      case 0x04 ... 0x07: return UNW_REG_R4 + (abreg - 0x04);
	      case 0x22 ... 0x25: return UNW_REG_F2 + (abreg - 0x22);
	      case 0x30 ... 0x3f: return UNW_REG_F16 + (abreg - 0x30);
	      case 0x41 ... 0x45: return UNW_REG_B1 + (abreg - 0x41);
	      case 0x60: return UNW_REG_PR;
	      case 0x61: return UNW_REG_PSP;
	      case 0x62: return memory ? UNW_REG_PRI_UNAT_MEM : UNW_REG_PRI_UNAT_GR;
	      case 0x63: return UNW_REG_RP;
	      case 0x64: return UNW_REG_BSP;
	      case 0x65: return UNW_REG_BSPSTORE;
	      case 0x66: return UNW_REG_RNAT;
	      case 0x67: return UNW_REG_UNAT;
	      case 0x68: return UNW_REG_FPSR;
	      case 0x69: return UNW_REG_PFS;
	      case 0x6a: return UNW_REG_LC;
	      default:
		break;
	}
	UNW_DPRINT(0, "unwind.%s: bad abreg=0x%x\n", __FUNCTION__, abreg);
	return UNW_REG_LC;
}

static void
set_reg (struct unw_reg_info *reg, enum unw_where where, int when, unsigned long val)
{
	reg->val = val;
	reg->where = where;
	if (reg->when == UNW_WHEN_NEVER)
		reg->when = when;
}

static void
alloc_spill_area (unsigned long *offp, unsigned long regsize,
		  struct unw_reg_info *lo, struct unw_reg_info *hi)
{
	struct unw_reg_info *reg;

	for (reg = hi; reg >= lo; --reg) {
		if (reg->where == UNW_WHERE_SPILL_HOME) {
			reg->where = UNW_WHERE_PSPREL;
			*offp -= regsize;
			reg->val = *offp;
		}
	}
}

static inline void
spill_next_when (struct unw_reg_info **regp, struct unw_reg_info *lim, unw_word t)
{
	struct unw_reg_info *reg;

	for (reg = *regp; reg <= lim; ++reg) {
		if (reg->where == UNW_WHERE_SPILL_HOME) {
			reg->when = t;
			*regp = reg + 1;
			return;
		}
	}
	UNW_DPRINT(0, "unwind.%s: excess spill!\n",  __FUNCTION__);
}

static inline void
finish_prologue (struct unw_state_record *sr)
{
	struct unw_reg_info *reg;
	unsigned long off;
	int i;

	/*
	 * First, resolve implicit register save locations (see Section "11.4.2.3 Rules
	 * for Using Unwind Descriptors", rule 3):
	 */
	for (i = 0; i < (int) ARRAY_SIZE(unw.save_order); ++i) {
		reg = sr->curr.reg + unw.save_order[i];
		if (reg->where == UNW_WHERE_GR_SAVE) {
			reg->where = UNW_WHERE_GR;
			reg->val = sr->gr_save_loc++;
		}
	}

	/*
	 * Next, compute when the fp, general, and branch registers get
	 * saved.  This must come before alloc_spill_area() because
	 * we need to know which registers are spilled to their home
	 * locations.
	 */
	if (sr->imask) {
		unsigned char kind, mask = 0, *cp = sr->imask;
		int t;
		static const unsigned char limit[3] = {
			UNW_REG_F31, UNW_REG_R7, UNW_REG_B5
		};
		struct unw_reg_info *(regs[3]);

		regs[0] = sr->curr.reg + UNW_REG_F2;
		regs[1] = sr->curr.reg + UNW_REG_R4;
		regs[2] = sr->curr.reg + UNW_REG_B1;

		for (t = 0; t < sr->region_len; ++t) {
			if ((t & 3) == 0)
				mask = *cp++;
			kind = (mask >> 2*(3-(t & 3))) & 3;
			if (kind > 0)
				spill_next_when(&regs[kind - 1], sr->curr.reg + limit[kind - 1],
						sr->region_start + t);
		}
	}
	/*
	 * Next, lay out the memory stack spill area:
	 */
	if (sr->any_spills) {
		off = sr->spill_offset;
		alloc_spill_area(&off, 16, sr->curr.reg + UNW_REG_F2, sr->curr.reg + UNW_REG_F31);
		alloc_spill_area(&off,  8, sr->curr.reg + UNW_REG_B1, sr->curr.reg + UNW_REG_B5);
		alloc_spill_area(&off,  8, sr->curr.reg + UNW_REG_R4, sr->curr.reg + UNW_REG_R7);
	}
}

/*
 * Region header descriptors.
 */

static void
desc_prologue (int body, unw_word rlen, unsigned char mask, unsigned char grsave,
	       struct unw_state_record *sr)
{
	int i, region_start;

	if (!(sr->in_body || sr->first_region))
		finish_prologue(sr);
	sr->first_region = 0;

	/* check if we're done: */
	if (sr->when_target < sr->region_start + sr->region_len) {
		sr->done = 1;
		return;
	}

	region_start = sr->region_start + sr->region_len;

	for (i = 0; i < sr->epilogue_count; ++i)
		pop(sr);
	sr->epilogue_count = 0;
	sr->epilogue_start = UNW_WHEN_NEVER;

	sr->region_start = region_start;
	sr->region_len = rlen;
	sr->in_body = body;

	if (!body) {
		push(sr);

		for (i = 0; i < 4; ++i) {
			if (mask & 0x8)
				set_reg(sr->curr.reg + unw.save_order[i], UNW_WHERE_GR,
					sr->region_start + sr->region_len - 1, grsave++);
			mask <<= 1;
		}
		sr->gr_save_loc = grsave;
		sr->any_spills = 0;
		sr->imask = NULL;
		sr->spill_offset = 0x10;	/* default to psp+16 */
	}
}

/*
 * Prologue descriptors.
 */

static inline void
desc_abi (unsigned char abi, unsigned char context, struct unw_state_record *sr)
{
	if (abi == 3 && context == 'i') {
		sr->flags |= UNW_FLAG_INTERRUPT_FRAME;
		UNW_DPRINT(3, "unwind.%s: interrupt frame\n",  __FUNCTION__);
	}
	else
		UNW_DPRINT(0, "unwind%s: ignoring unwabi(abi=0x%x,context=0x%x)\n",
				__FUNCTION__, abi, context);
}

static inline void
desc_br_gr (unsigned char brmask, unsigned char gr, struct unw_state_record *sr)
{
	int i;

	for (i = 0; i < 5; ++i) {
		if (brmask & 1)
			set_reg(sr->curr.reg + UNW_REG_B1 + i, UNW_WHERE_GR,
				sr->region_start + sr->region_len - 1, gr++);
		brmask >>= 1;
	}
}

static inline void
desc_br_mem (unsigned char brmask, struct unw_state_record *sr)
{
	int i;

	for (i = 0; i < 5; ++i) {
		if (brmask & 1) {
			set_reg(sr->curr.reg + UNW_REG_B1 + i, UNW_WHERE_SPILL_HOME,
				sr->region_start + sr->region_len - 1, 0);
			sr->any_spills = 1;
		}
		brmask >>= 1;
	}
}

static inline void
desc_frgr_mem (unsigned char grmask, unw_word frmask, struct unw_state_record *sr)
{
	int i;

	for (i = 0; i < 4; ++i) {
		if ((grmask & 1) != 0) {
			set_reg(sr->curr.reg + UNW_REG_R4 + i, UNW_WHERE_SPILL_HOME,
				sr->region_start + sr->region_len - 1, 0);
			sr->any_spills = 1;
		}
		grmask >>= 1;
	}
	for (i = 0; i < 20; ++i) {
		if ((frmask & 1) != 0) {
			int base = (i < 4) ? UNW_REG_F2 : UNW_REG_F16 - 4;
			set_reg(sr->curr.reg + base + i, UNW_WHERE_SPILL_HOME,
				sr->region_start + sr->region_len - 1, 0);
			sr->any_spills = 1;
		}
		frmask >>= 1;
	}
}

static inline void
desc_fr_mem (unsigned char frmask, struct unw_state_record *sr)
{
	int i;

	for (i = 0; i < 4; ++i) {
		if ((frmask & 1) != 0) {
			set_reg(sr->curr.reg + UNW_REG_F2 + i, UNW_WHERE_SPILL_HOME,
				sr->region_start + sr->region_len - 1, 0);
			sr->any_spills = 1;
		}
		frmask >>= 1;
	}