unwind.c

xen虚拟机源代码安装包

}

static inline void
desc_gr_gr (unsigned char grmask, unsigned char gr, 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_GR,
				sr->region_start + sr->region_len - 1, gr++);
		grmask >>= 1;
	}
}

static inline void
desc_gr_mem (unsigned char grmask, 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;
	}
}

static inline void
desc_mem_stack_f (unw_word t, unw_word size, struct unw_state_record *sr)
{
	set_reg(sr->curr.reg + UNW_REG_PSP, UNW_WHERE_NONE,
		sr->region_start + min_t(int, t, sr->region_len - 1), 16*size);
}

static inline void
desc_mem_stack_v (unw_word t, struct unw_state_record *sr)
{
	sr->curr.reg[UNW_REG_PSP].when = sr->region_start + min_t(int, t, sr->region_len - 1);
}

static inline void
desc_reg_gr (unsigned char reg, unsigned char dst, struct unw_state_record *sr)
{
	set_reg(sr->curr.reg + reg, UNW_WHERE_GR, sr->region_start + sr->region_len - 1, dst);
}

static inline void
desc_reg_psprel (unsigned char reg, unw_word pspoff, struct unw_state_record *sr)
{
	set_reg(sr->curr.reg + reg, UNW_WHERE_PSPREL, sr->region_start + sr->region_len - 1,
		0x10 - 4*pspoff);
}

static inline void
desc_reg_sprel (unsigned char reg, unw_word spoff, struct unw_state_record *sr)
{
	set_reg(sr->curr.reg + reg, UNW_WHERE_SPREL, sr->region_start + sr->region_len - 1,
		4*spoff);
}

static inline void
desc_rp_br (unsigned char dst, struct unw_state_record *sr)
{
	sr->return_link_reg = dst;
}

static inline void
desc_reg_when (unsigned char regnum, unw_word t, struct unw_state_record *sr)
{
	struct unw_reg_info *reg = sr->curr.reg + regnum;

	if (reg->where == UNW_WHERE_NONE)
		reg->where = UNW_WHERE_GR_SAVE;
	reg->when = sr->region_start + min_t(int, t, sr->region_len - 1);
}

static inline void
desc_spill_base (unw_word pspoff, struct unw_state_record *sr)
{
	sr->spill_offset = 0x10 - 4*pspoff;
}

static inline unsigned char *
desc_spill_mask (unsigned char *imaskp, struct unw_state_record *sr)
{
	sr->imask = imaskp;
	return imaskp + (2*sr->region_len + 7)/8;
}

/*
 * Body descriptors.
 */
static inline void
desc_epilogue (unw_word t, unw_word ecount, struct unw_state_record *sr)
{
	sr->epilogue_start = sr->region_start + sr->region_len - 1 - t;
	sr->epilogue_count = ecount + 1;
}

static inline void
desc_copy_state (unw_word label, struct unw_state_record *sr)
{
	struct unw_labeled_state *ls;

	for (ls = sr->labeled_states; ls; ls = ls->next) {
		if (ls->label == label) {
			free_state_stack(&sr->curr);
			memcpy(&sr->curr, &ls->saved_state, sizeof(sr->curr));
			sr->curr.next = dup_state_stack(ls->saved_state.next);
			return;
		}
	}
	printk(KERN_ERR "unwind: failed to find state labeled 0x%lx\n", label);
}

static inline void
desc_label_state (unw_word label, struct unw_state_record *sr)
{
	struct unw_labeled_state *ls;

	ls = alloc_labeled_state();
	if (!ls) {
		printk(KERN_ERR "unwind.desc_label_state(): out of memory\n");
		return;
	}
	ls->label = label;
	memcpy(&ls->saved_state, &sr->curr, sizeof(ls->saved_state));
	ls->saved_state.next = dup_state_stack(sr->curr.next);

	/* insert into list of labeled states: */
	ls->next = sr->labeled_states;
	sr->labeled_states = ls;
}

/*
 * General descriptors.
 */

static inline int
desc_is_active (unsigned char qp, unw_word t, struct unw_state_record *sr)
{
	if (sr->when_target <= sr->region_start + min_t(int, t, sr->region_len - 1))
		return 0;
	if (qp > 0) {
		if ((sr->pr_val & (1UL << qp)) == 0)
			return 0;
		sr->pr_mask |= (1UL << qp);
	}
	return 1;
}

static inline void
desc_restore_p (unsigned char qp, unw_word t, unsigned char abreg, struct unw_state_record *sr)
{
	struct unw_reg_info *r;

	if (!desc_is_active(qp, t, sr))
		return;

	r = sr->curr.reg + decode_abreg(abreg, 0);
	r->where = UNW_WHERE_NONE;
	r->when = UNW_WHEN_NEVER;
	r->val = 0;
}

static inline void
desc_spill_reg_p (unsigned char qp, unw_word t, unsigned char abreg, unsigned char x,
		     unsigned char ytreg, struct unw_state_record *sr)
{
	enum unw_where where = UNW_WHERE_GR;
	struct unw_reg_info *r;

	if (!desc_is_active(qp, t, sr))
		return;

	if (x)
		where = UNW_WHERE_BR;
	else if (ytreg & 0x80)
		where = UNW_WHERE_FR;

	r = sr->curr.reg + decode_abreg(abreg, 0);
	r->where = where;
	r->when = sr->region_start + min_t(int, t, sr->region_len - 1);
	r->val = (ytreg & 0x7f);
}

static inline void
desc_spill_psprel_p (unsigned char qp, unw_word t, unsigned char abreg, unw_word pspoff,
		     struct unw_state_record *sr)
{
	struct unw_reg_info *r;

	if (!desc_is_active(qp, t, sr))
		return;

	r = sr->curr.reg + decode_abreg(abreg, 1);
	r->where = UNW_WHERE_PSPREL;
	r->when = sr->region_start + min_t(int, t, sr->region_len - 1);
	r->val = 0x10 - 4*pspoff;
}

static inline void
desc_spill_sprel_p (unsigned char qp, unw_word t, unsigned char abreg, unw_word spoff,
		       struct unw_state_record *sr)
{
	struct unw_reg_info *r;

	if (!desc_is_active(qp, t, sr))
		return;

	r = sr->curr.reg + decode_abreg(abreg, 1);
	r->where = UNW_WHERE_SPREL;
	r->when = sr->region_start + min_t(int, t, sr->region_len - 1);
	r->val = 4*spoff;
}

#define UNW_DEC_BAD_CODE(code)			printk(KERN_ERR "unwind: unknown code 0x%02x\n", \
						       code);

/*
 * region headers:
 */
#define UNW_DEC_PROLOGUE_GR(fmt,r,m,gr,arg)	desc_prologue(0,r,m,gr,arg)
#define UNW_DEC_PROLOGUE(fmt,b,r,arg)		desc_prologue(b,r,0,32,arg)
/*
 * prologue descriptors:
 */
#define UNW_DEC_ABI(fmt,a,c,arg)		desc_abi(a,c,arg)
#define UNW_DEC_BR_GR(fmt,b,g,arg)		desc_br_gr(b,g,arg)
#define UNW_DEC_BR_MEM(fmt,b,arg)		desc_br_mem(b,arg)
#define UNW_DEC_FRGR_MEM(fmt,g,f,arg)		desc_frgr_mem(g,f,arg)
#define UNW_DEC_FR_MEM(fmt,f,arg)		desc_fr_mem(f,arg)
#define UNW_DEC_GR_GR(fmt,m,g,arg)		desc_gr_gr(m,g,arg)
#define UNW_DEC_GR_MEM(fmt,m,arg)		desc_gr_mem(m,arg)
#define UNW_DEC_MEM_STACK_F(fmt,t,s,arg)	desc_mem_stack_f(t,s,arg)
#define UNW_DEC_MEM_STACK_V(fmt,t,arg)		desc_mem_stack_v(t,arg)
#define UNW_DEC_REG_GR(fmt,r,d,arg)		desc_reg_gr(r,d,arg)
#define UNW_DEC_REG_PSPREL(fmt,r,o,arg)		desc_reg_psprel(r,o,arg)
#define UNW_DEC_REG_SPREL(fmt,r,o,arg)		desc_reg_sprel(r,o,arg)
#define UNW_DEC_REG_WHEN(fmt,r,t,arg)		desc_reg_when(r,t,arg)
#define UNW_DEC_PRIUNAT_WHEN_GR(fmt,t,arg)	desc_reg_when(UNW_REG_PRI_UNAT_GR,t,arg)
#define UNW_DEC_PRIUNAT_WHEN_MEM(fmt,t,arg)	desc_reg_when(UNW_REG_PRI_UNAT_MEM,t,arg)
#define UNW_DEC_PRIUNAT_GR(fmt,r,arg)		desc_reg_gr(UNW_REG_PRI_UNAT_GR,r,arg)
#define UNW_DEC_PRIUNAT_PSPREL(fmt,o,arg)	desc_reg_psprel(UNW_REG_PRI_UNAT_MEM,o,arg)
#define UNW_DEC_PRIUNAT_SPREL(fmt,o,arg)	desc_reg_sprel(UNW_REG_PRI_UNAT_MEM,o,arg)
#define UNW_DEC_RP_BR(fmt,d,arg)		desc_rp_br(d,arg)
#define UNW_DEC_SPILL_BASE(fmt,o,arg)		desc_spill_base(o,arg)
#define UNW_DEC_SPILL_MASK(fmt,m,arg)		(m = desc_spill_mask(m,arg))
/*
 * body descriptors:
 */
#define UNW_DEC_EPILOGUE(fmt,t,c,arg)		desc_epilogue(t,c,arg)
#define UNW_DEC_COPY_STATE(fmt,l,arg)		desc_copy_state(l,arg)
#define UNW_DEC_LABEL_STATE(fmt,l,arg)		desc_label_state(l,arg)
/*
 * general unwind descriptors:
 */
#define UNW_DEC_SPILL_REG_P(f,p,t,a,x,y,arg)	desc_spill_reg_p(p,t,a,x,y,arg)
#define UNW_DEC_SPILL_REG(f,t,a,x,y,arg)	desc_spill_reg_p(0,t,a,x,y,arg)
#define UNW_DEC_SPILL_PSPREL_P(f,p,t,a,o,arg)	desc_spill_psprel_p(p,t,a,o,arg)
#define UNW_DEC_SPILL_PSPREL(f,t,a,o,arg)	desc_spill_psprel_p(0,t,a,o,arg)
#define UNW_DEC_SPILL_SPREL_P(f,p,t,a,o,arg)	desc_spill_sprel_p(p,t,a,o,arg)
#define UNW_DEC_SPILL_SPREL(f,t,a,o,arg)	desc_spill_sprel_p(0,t,a,o,arg)
#define UNW_DEC_RESTORE_P(f,p,t,a,arg)		desc_restore_p(p,t,a,arg)
#define UNW_DEC_RESTORE(f,t,a,arg)		desc_restore_p(0,t,a,arg)

#include "unwind_decoder.c"


/* Unwind scripts. */

static inline unw_hash_index_t
hash (unsigned long ip)
{
#	define hashmagic	0x9e3779b97f4a7c16UL	/* based on (sqrt(5)/2-1)*2^64 */

	return (ip >> 4)*hashmagic >> (64 - UNW_LOG_HASH_SIZE);
#undef hashmagic
}

static inline long
cache_match (struct unw_script *script, unsigned long ip, unsigned long pr)
{
	read_lock(&script->lock);
	if (ip == script->ip && ((pr ^ script->pr_val) & script->pr_mask) == 0)
		/* keep the read lock... */
		return 1;
	read_unlock(&script->lock);
	return 0;
}

static inline struct unw_script *
script_lookup (struct unw_frame_info *info)
{
	struct unw_script *script = unw.cache + info->hint;
	unsigned short index;
	unsigned long ip, pr;

	if (UNW_DEBUG_ON(0))
		return NULL;	/* Always regenerate scripts in debug mode */

	STAT(++unw.stat.cache.lookups);

	ip = info->ip;
	pr = info->pr;

	if (cache_match(script, ip, pr)) {
		STAT(++unw.stat.cache.hinted_hits);
		return script;
	}

	index = unw.hash[hash(ip)];
	if (index >= UNW_CACHE_SIZE)
		return NULL;

	script = unw.cache + index;
	while (1) {
		if (cache_match(script, ip, pr)) {
			/* update hint; no locking required as single-word writes are atomic */
			STAT(++unw.stat.cache.normal_hits);
			unw.cache[info->prev_script].hint = script - unw.cache;
			return script;
		}
		if (script->coll_chain >= UNW_HASH_SIZE)
			return NULL;
		script = unw.cache + script->coll_chain;
		STAT(++unw.stat.cache.collision_chain_traversals);
	}
}

/*
 * On returning, a write lock for the SCRIPT is still being held.
 */
static inline struct unw_script *
script_new (unsigned long ip)
{
	struct unw_script *script, *prev, *tmp;
	unw_hash_index_t index;
	unsigned short head;

	STAT(++unw.stat.script.news);

	/*
	 * Can't (easily) use cmpxchg() here because of ABA problem
	 * that is intrinsic in cmpxchg()...
	 */
	head = unw.lru_head;
	script = unw.cache + head;
	unw.lru_head = script->lru_chain;

	/*
	 * We'd deadlock here if we interrupted a thread that is holding a read lock on
	 * script->lock.  Thus, if the write_trylock() fails, we simply bail out.  The
	 * alternative would be to disable interrupts whenever we hold a read-lock, but
	 * that seems silly.
	 */
	if (!write_trylock(&script->lock))
		return NULL;

	/* re-insert script at the tail of the LRU chain: */
	unw.cache[unw.lru_tail].lru_chain = head;
	unw.lru_tail = head;

	/* remove the old script from the hash table (if it's there): */
	if (script->ip) {
		index = hash(script->ip);
		tmp = unw.cache + unw.hash[index];
		prev = NULL;
		while (1) {
			if (tmp == script) {
				if (prev)
					prev->coll_chain = tmp->coll_chain;
				else
					unw.hash[index] = tmp->coll_chain;
				break;
			} else
				prev = tmp;
			if (tmp->coll_chain >= UNW_CACHE_SIZE)
			/* old script wasn't in the hash-table */
				break;
			tmp = unw.cache + tmp->coll_chain;
		}
	}

	/* enter new script in the hash table */
	index = hash(ip);
	script->coll_chain = unw.hash[index];
	unw.hash[index] = script - unw.cache;

	script->ip = ip;	/* set new IP while we're holding the locks */

	STAT(if (script->coll_chain < UNW_CACHE_SIZE) ++unw.stat.script.collisions);

	script->flags = 0;
	script->hint = 0;
	script->count = 0;
	return script;
}

static void
script_finalize (struct unw_script *script, struct unw_state_record *sr)
{
	script->pr_mask = sr->pr_mask;
	script->pr_val = sr->pr_val;
	/*
	 * We could down-grade our write-lock on script->lock here but
	 * the rwlock API doesn't offer atomic lock downgrading, so
	 * we'll just keep the write-lock and release it later when
	 * we're done using the script.
	 */
}

static inline void
script_emit (struct unw_script *script, struct unw_insn insn)
{
	if (script->count >= UNW_MAX_SCRIPT_LEN) {
		UNW_DPRINT(0, "unwind.%s: script exceeds maximum size of %u instructions!\n",
			__FUNCTION__, UNW_MAX_SCRIPT_LEN);
		return;
	}
	script->insn[script->count++] = insn;
}

static inline void
emit_nat_info (struct unw_state_record *sr, int i, struct unw_script *script)
{
	struct unw_reg_info *r = sr->curr.reg + i;
	enum unw_insn_opcode opc;
	struct unw_insn insn;
	unsigned long val = 0;

	switch (r->where) {
	      case UNW_WHERE_GR:
		if (r->val >= 32) {
			/* register got spilled to a stacked register */
			opc = UNW_INSN_SETNAT_TYPE;
			val = UNW_NAT_REGSTK;
		} else
			/* register got spilled to a scratch register */
			opc = UNW_INSN_SETNAT_MEMSTK;
		break;

	      case UNW_WHERE_FR:
		opc = UNW_INSN_SETNAT_TYPE;
		val = UNW_NAT_VAL;
		break;

	      case UNW_WHERE_BR:
		opc = UNW_INSN_SETNAT_TYPE;
		val = UNW_NAT_NONE;
		break;

	      case UNW_WHERE_PSPREL:
	      case UNW_WHERE_SPREL:
		opc = UNW_INSN_SETNAT_MEMSTK;
		break;

	      default:
		UNW_DPRINT(0, "unwind.%s: don't know how to emit nat info for where = %u\n",
			   __FUNCTION__, r->where);
		return;
	}
	insn.opc = opc;
	insn.dst = unw.preg_index[i];
	insn.val = val;
	script_emit(script, insn);
}

static void
compile_reg (struct unw_state_record *sr, int i, struct unw_script *script)
{
	struct unw_reg_info *r = sr->curr.reg + i;
	enum unw_insn_opcode opc;
	unsigned long val, rval;
	struct unw_insn insn;
	long need_nat_info;