arch/sparc/net/bpf_jit_comp.c - kernel/msm-4.9 - Gitiles

 #include <linux/moduleloader.h>
 #include <linux/workqueue.h>
 #include <linux/netdevice.h>
 #include <linux/filter.h>
 #include <linux/cache.h>

 #include <asm/cacheflush.h>
 #include <asm/ptrace.h>

 #include "bpf_jit.h"

 int bpf_jit_enable __read_mostly;

 static inline bool is_simm13(unsigned int value)
 {
 	return value + 0x1000 < 0x2000;
 }

 static void bpf_flush_icache(void *start_, void *end_)
 {
 #ifdef CONFIG_SPARC64
 	/* Cheetah's I-cache is fully coherent.  */
 	if (tlb_type == spitfire) {
 		unsigned long start = (unsigned long) start_;
 		unsigned long end = (unsigned long) end_;

 		start &= ~7UL;
 		end = (end + 7UL) & ~7UL;
 		while (start < end) {
 			flushi(start);
 			start += 32;
 		}
 	}
 #endif
 }

 #define SEEN_DATAREF 1 /* might call external helpers */
 #define SEEN_XREG    2 /* ebx is used */
 #define SEEN_MEM     4 /* use mem[] for temporary storage */

 #define S13(X)		((X) & 0x1fff)
 #define IMMED		0x00002000
 #define RD(X)		((X) << 25)
 #define RS1(X)		((X) << 14)
 #define RS2(X)		((X))
 #define OP(X)		((X) << 30)
 #define OP2(X)		((X) << 22)
 #define OP3(X)		((X) << 19)
 #define COND(X)		((X) << 25)
 #define F1(X)		OP(X)
 #define F2(X, Y)	(OP(X) | OP2(Y))
 #define F3(X, Y)	(OP(X) | OP3(Y))

 #define CONDN		COND(0x0)
 #define CONDE		COND(0x1)
 #define CONDLE		COND(0x2)
 #define CONDL		COND(0x3)
 #define CONDLEU		COND(0x4)
 #define CONDCS		COND(0x5)
 #define CONDNEG		COND(0x6)
 #define CONDVC		COND(0x7)
 #define CONDA		COND(0x8)
 #define CONDNE		COND(0x9)
 #define CONDG		COND(0xa)
 #define CONDGE		COND(0xb)
 #define CONDGU		COND(0xc)
 #define CONDCC		COND(0xd)
 #define CONDPOS		COND(0xe)
 #define CONDVS		COND(0xf)

 #define CONDGEU		CONDCC
 #define CONDLU		CONDCS

 #define WDISP22(X)	(((X) >> 2) & 0x3fffff)

 #define BA		(F2(0, 2) | CONDA)
 #define BGU		(F2(0, 2) | CONDGU)
 #define BLEU		(F2(0, 2) | CONDLEU)
 #define BGEU		(F2(0, 2) | CONDGEU)
 #define BLU		(F2(0, 2) | CONDLU)
 #define BE		(F2(0, 2) | CONDE)
 #define BNE		(F2(0, 2) | CONDNE)

 #ifdef CONFIG_SPARC64
 #define BNE_PTR		(F2(0, 1) | CONDNE | (2 << 20))
 #else
 #define BNE_PTR		BNE
 #endif

 #define SETHI(K, REG)	\
 	(F2(0, 0x4) | RD(REG) | (((K) >> 10) & 0x3fffff))
 #define OR_LO(K, REG)	\
 	(F3(2, 0x02) | IMMED | RS1(REG) | ((K) & 0x3ff) | RD(REG))

 #define ADD		F3(2, 0x00)
 #define AND		F3(2, 0x01)
 #define ANDCC		F3(2, 0x11)
 #define OR		F3(2, 0x02)
 #define SUB		F3(2, 0x04)
 #define SUBCC		F3(2, 0x14)
 #define MUL		F3(2, 0x0a)	/* umul */
 #define DIV		F3(2, 0x0e)	/* udiv */
 #define SLL		F3(2, 0x25)
 #define SRL		F3(2, 0x26)
 #define JMPL		F3(2, 0x38)
 #define CALL		F1(1)
 #define BR		F2(0, 0x01)
 #define RD_Y		F3(2, 0x28)
 #define WR_Y		F3(2, 0x30)

 #define LD32		F3(3, 0x00)
 #define LD8		F3(3, 0x01)
 #define LD16		F3(3, 0x02)
 #define LD64		F3(3, 0x0b)
 #define ST32		F3(3, 0x04)

 #ifdef CONFIG_SPARC64
 #define LDPTR		LD64
 #define BASE_STACKFRAME	176
 #else
 #define LDPTR		LD32
 #define BASE_STACKFRAME	96
 #endif

 #define LD32I		(LD32 | IMMED)
 #define LD8I		(LD8 | IMMED)
 #define LD16I		(LD16 | IMMED)
 #define LD64I		(LD64 | IMMED)
 #define LDPTRI		(LDPTR | IMMED)
 #define ST32I		(ST32 | IMMED)

 #define emit_nop()		\
 do {				\
 	*prog++ = SETHI(0, G0);	\
 } while (0)

 #define emit_neg()					\
 do {	/* sub %g0, r_A, r_A */				\
 	*prog++ = SUB | RS1(G0) | RS2(r_A) | RD(r_A);	\
 } while (0)

 #define emit_reg_move(FROM, TO)				\
 do {	/* or %g0, FROM, TO */				\
 	*prog++ = OR | RS1(G0) | RS2(FROM) | RD(TO);	\
 } while (0)

 #define emit_clear(REG)					\
 do {	/* or %g0, %g0, REG */				\
 	*prog++ = OR | RS1(G0) | RS2(G0) | RD(REG);	\
 } while (0)

 #define emit_set_const(K, REG)					\
 do {	/* sethi %hi(K), REG */					\
 	*prog++ = SETHI(K, REG);				\
 	/* or REG, %lo(K), REG */				\
 	*prog++ = OR_LO(K, REG);				\
 } while (0)

 	/* Emit
 	 *
 	 *	OP	r_A, r_X, r_A
 	 */
 #define emit_alu_X(OPCODE)					\
 do {								\
 	seen |= SEEN_XREG;					\
 	*prog++ = OPCODE | RS1(r_A) | RS2(r_X) | RD(r_A);	\
 } while (0)

 	/* Emit either:
 	 *
 	 *	OP	r_A, K, r_A
 	 *
 	 * or
 	 *
 	 *	sethi	%hi(K), r_TMP
 	 *	or	r_TMP, %lo(K), r_TMP
 	 *	OP	r_A, r_TMP, r_A
 	 *
 	 * depending upon whether K fits in a signed 13-bit
 	 * immediate instruction field.  Emit nothing if K
 	 * is zero.
 	 */
 #define emit_alu_K(OPCODE, K)					\
 do {								\
 	if (K) {						\
 		unsigned int _insn = OPCODE;			\
 		_insn |= RS1(r_A) | RD(r_A);			\
 		if (is_simm13(K)) {				\
 			*prog++ = _insn | IMMED | S13(K);	\
 		} else {					\
 			emit_set_const(K, r_TMP);		\
 			*prog++ = _insn | RS2(r_TMP);		\
 		}						\
 	}							\
 } while (0)

 #define emit_loadimm(K, DEST)						\
 do {									\
 	if (is_simm13(K)) {						\
 		/* or %g0, K, DEST */					\
 		*prog++ = OR | IMMED | RS1(G0) | S13(K) | RD(DEST);	\
 	} else {							\
 		emit_set_const(K, DEST);				\
 	}								\
 } while (0)

 #define emit_loadptr(BASE, STRUCT, FIELD, DEST)				\
 do {	unsigned int _off = offsetof(STRUCT, FIELD);			\
 	BUILD_BUG_ON(FIELD_SIZEOF(STRUCT, FIELD) != sizeof(void *));	\
 	*prog++ = LDPTRI | RS1(BASE) | S13(_off) | RD(DEST);		\
 } while (0)

 #define emit_load32(BASE, STRUCT, FIELD, DEST)				\
 do {	unsigned int _off = offsetof(STRUCT, FIELD);			\
 	BUILD_BUG_ON(FIELD_SIZEOF(STRUCT, FIELD) != sizeof(u32));	\
 	*prog++ = LD32I | RS1(BASE) | S13(_off) | RD(DEST);		\
 } while (0)

 #define emit_load16(BASE, STRUCT, FIELD, DEST)				\
 do {	unsigned int _off = offsetof(STRUCT, FIELD);			\
 	BUILD_BUG_ON(FIELD_SIZEOF(STRUCT, FIELD) != sizeof(u16));	\
 	*prog++ = LD16I | RS1(BASE) | S13(_off) | RD(DEST);		\
 } while (0)

 #define __emit_load8(BASE, STRUCT, FIELD, DEST)				\
 do {	unsigned int _off = offsetof(STRUCT, FIELD);			\
 	*prog++ = LD8I | RS1(BASE) | S13(_off) | RD(DEST);		\
 } while (0)

 #define emit_load8(BASE, STRUCT, FIELD, DEST)				\
 do {	BUILD_BUG_ON(FIELD_SIZEOF(STRUCT, FIELD) != sizeof(u8));	\
 	__emit_load8(BASE, STRUCT, FIELD, DEST);			\
 } while (0)

 #define emit_ldmem(OFF, DEST)					\
 do {	*prog++ = LD32I | RS1(FP) | S13(-(OFF)) | RD(DEST);	\
 } while (0)

 #define emit_stmem(OFF, SRC)					\
 do {	*prog++ = LD32I | RS1(FP) | S13(-(OFF)) | RD(SRC);	\
 } while (0)

 #ifdef CONFIG_SMP
 #ifdef CONFIG_SPARC64
 #define emit_load_cpu(REG)						\
 	emit_load16(G6, struct thread_info, cpu, REG)
 #else
 #define emit_load_cpu(REG)						\
 	emit_load32(G6, struct thread_info, cpu, REG)
 #endif
 #else
 #define emit_load_cpu(REG)	emit_clear(REG)
 #endif

 #define emit_skb_loadptr(FIELD, DEST) \
 	emit_loadptr(r_SKB, struct sk_buff, FIELD, DEST)
 #define emit_skb_load32(FIELD, DEST) \
 	emit_load32(r_SKB, struct sk_buff, FIELD, DEST)
 #define emit_skb_load16(FIELD, DEST) \
 	emit_load16(r_SKB, struct sk_buff, FIELD, DEST)
 #define __emit_skb_load8(FIELD, DEST) \
 	__emit_load8(r_SKB, struct sk_buff, FIELD, DEST)
 #define emit_skb_load8(FIELD, DEST) \
 	emit_load8(r_SKB, struct sk_buff, FIELD, DEST)

 #define emit_jmpl(BASE, IMM_OFF, LREG) \
 	*prog++ = (JMPL | IMMED | RS1(BASE) | S13(IMM_OFF) | RD(LREG))

 #define emit_call(FUNC)					\
 do {	void *_here = image + addrs[i] - 8;		\
 	unsigned int _off = (void *)(FUNC) - _here;	\
 	*prog++ = CALL | (((_off) >> 2) & 0x3fffffff);	\
 	emit_nop();					\
 } while (0)

 #define emit_branch(BR_OPC, DEST)			\
 do {	unsigned int _here = addrs[i] - 8;		\
 	*prog++ = BR_OPC | WDISP22((DEST) - _here);	\
 } while (0)

 #define emit_branch_off(BR_OPC, OFF)			\
 do {	*prog++ = BR_OPC | WDISP22(OFF);		\
 } while (0)

 #define emit_jump(DEST)		emit_branch(BA, DEST)

 #define emit_read_y(REG)	*prog++ = RD_Y | RD(REG)
 #define emit_write_y(REG)	*prog++ = WR_Y | IMMED | RS1(REG) | S13(0)

 #define emit_cmp(R1, R2) \
 	*prog++ = (SUBCC | RS1(R1) | RS2(R2) | RD(G0))

 #define emit_cmpi(R1, IMM) \
 	*prog++ = (SUBCC | IMMED | RS1(R1) | S13(IMM) | RD(G0));

 #define emit_btst(R1, R2) \
 	*prog++ = (ANDCC | RS1(R1) | RS2(R2) | RD(G0))

 #define emit_btsti(R1, IMM) \
 	*prog++ = (ANDCC | IMMED | RS1(R1) | S13(IMM) | RD(G0));

 #define emit_sub(R1, R2, R3) \
 	*prog++ = (SUB | RS1(R1) | RS2(R2) | RD(R3))

 #define emit_subi(R1, IMM, R3) \
 	*prog++ = (SUB | IMMED | RS1(R1) | S13(IMM) | RD(R3))

 #define emit_add(R1, R2, R3) \
 	*prog++ = (ADD | RS1(R1) | RS2(R2) | RD(R3))

 #define emit_addi(R1, IMM, R3) \
 	*prog++ = (ADD | IMMED | RS1(R1) | S13(IMM) | RD(R3))

 #define emit_alloc_stack(SZ) \
 	*prog++ = (SUB | IMMED | RS1(SP) | S13(SZ) | RD(SP))

 #define emit_release_stack(SZ) \
 	*prog++ = (ADD | IMMED | RS1(SP) | S13(SZ) | RD(SP))

 /* A note about branch offset calculations.  The addrs[] array,
  * indexed by BPF instruction, records the address after all the
  * sparc instructions emitted for that BPF instruction.
  *
  * The most common case is to emit a branch at the end of such
  * a code sequence.  So this would be two instructions, the
  * branch and it's delay slot.
  *
  * Therefore by default the branch emitters calculate the branch
  * offset field as:
  *
  *	destination - (addrs[i] - 8)
  *
  * This "addrs[i] - 8" is the address of the branch itself or
  * what "." would be in assembler notation.  The "8" part is
  * how we take into consideration the branch and it's delay
  * slot mentioned above.
  *
  * Sometimes we need to emit a branch earlier in the code
  * sequence.  And in these situations we adjust "destination"
  * to accomodate this difference.  For example, if we needed
  * to emit a branch (and it's delay slot) right before the
  * final instruction emitted for a BPF opcode, we'd use
  * "destination + 4" instead of just plain "destination" above.
  *
  * This is why you see all of these funny emit_branch() and
  * emit_jump() calls with adjusted offsets.
  */

 void bpf_jit_compile(struct sk_filter *fp)
 {
 	unsigned int cleanup_addr, proglen, oldproglen = 0;
 	u32 temp[8], *prog, *func, seen = 0, pass;
 	const struct sock_filter *filter = fp->insns;
 	int i, flen = fp->len, pc_ret0 = -1;
 	unsigned int *addrs;
 	void *image;

 	if (!bpf_jit_enable)
 		return;

 	addrs = kmalloc(flen * sizeof(*addrs), GFP_KERNEL);
 	if (addrs == NULL)
 		return;

 	/* Before first pass, make a rough estimation of addrs[]
 	 * each bpf instruction is translated to less than 64 bytes
 	 */
 	for (proglen = 0, i = 0; i < flen; i++) {
 		proglen += 64;
 		addrs[i] = proglen;
 	}
 	cleanup_addr = proglen; /* epilogue address */
 	image = NULL;
 	for (pass = 0; pass < 10; pass++) {
 		u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG | SEEN_DATAREF | SEEN_MEM) : seen;

 		/* no prologue/epilogue for trivial filters (RET something) */
 		proglen = 0;
 		prog = temp;

 		/* Prologue */
 		if (seen_or_pass0) {
 			if (seen_or_pass0 & SEEN_MEM) {
 				unsigned int sz = BASE_STACKFRAME;
 				sz += BPF_MEMWORDS * sizeof(u32);
 				emit_alloc_stack(sz);
 			}

 			/* Make sure we dont leek kernel memory. */
 			if (seen_or_pass0 & SEEN_XREG)
 				emit_clear(r_X);

 			/* If this filter needs to access skb data,
 			 * load %o4 and %o5 with:
 			 *  %o4 = skb->len - skb->data_len
 			 *  %o5 = skb->data
 			 * And also back up %o7 into r_saved_O7 so we can
 			 * invoke the stubs using 'call'.
 			 */
 			if (seen_or_pass0 & SEEN_DATAREF) {
 				emit_load32(r_SKB, struct sk_buff, len, r_HEADLEN);
 				emit_load32(r_SKB, struct sk_buff, data_len, r_TMP);
 				emit_sub(r_HEADLEN, r_TMP, r_HEADLEN);
 				emit_loadptr(r_SKB, struct sk_buff, data, r_SKB_DATA);
 			}
 		}
 		emit_reg_move(O7, r_saved_O7);

 		switch (filter[0].code) {
 		case BPF_S_RET_K:
 		case BPF_S_LD_W_LEN:
 		case BPF_S_ANC_PROTOCOL:
 		case BPF_S_ANC_PKTTYPE:
 		case BPF_S_ANC_IFINDEX:
 		case BPF_S_ANC_MARK:
 		case BPF_S_ANC_RXHASH:
 		case BPF_S_ANC_CPU:
 		case BPF_S_ANC_QUEUE:
 		case BPF_S_LD_W_ABS:
 		case BPF_S_LD_H_ABS:
 		case BPF_S_LD_B_ABS:
 			/* The first instruction sets the A register (or is
 			 * a "RET 'constant'")
 			 */
 			break;
 		default:
 			/* Make sure we dont leak kernel information to the
 			 * user.
 			 */
 			emit_clear(r_A); /* A = 0 */
 		}

 		for (i = 0; i < flen; i++) {
 			unsigned int K = filter[i].k;
 			unsigned int t_offset;
 			unsigned int f_offset;
 			u32 t_op, f_op;
 			int ilen;

 			switch (filter[i].code) {
 			case BPF_S_ALU_ADD_X:	/* A += X; */
 				emit_alu_X(ADD);
 				break;
 			case BPF_S_ALU_ADD_K:	/* A += K; */
 				emit_alu_K(ADD, K);
 				break;
 			case BPF_S_ALU_SUB_X:	/* A -= X; */
 				emit_alu_X(SUB);
 				break;
 			case BPF_S_ALU_SUB_K:	/* A -= K */
 				emit_alu_K(SUB, K);
 				break;
 			case BPF_S_ALU_AND_X:	/* A &= X */
 				emit_alu_X(AND);
 				break;
 			case BPF_S_ALU_AND_K:	/* A &= K */
 				emit_alu_K(AND, K);
 				break;
 			case BPF_S_ALU_OR_X:	/* A |= X */
 				emit_alu_X(OR);
 				break;
 			case BPF_S_ALU_OR_K:	/* A |= K */
 				emit_alu_K(OR, K);
 				break;
 			case BPF_S_ALU_LSH_X:	/* A <<= X */
 				emit_alu_X(SLL);
 				break;
 			case BPF_S_ALU_LSH_K:	/* A <<= K */
 				emit_alu_K(SLL, K);
 				break;
 			case BPF_S_ALU_RSH_X:	/* A >>= X */
 				emit_alu_X(SRL);
 				break;
 			case BPF_S_ALU_RSH_K:	/* A >>= K */
 				emit_alu_K(SRL, K);
 				break;
 			case BPF_S_ALU_MUL_X:	/* A *= X; */
 				emit_alu_X(MUL);
 				break;
 			case BPF_S_ALU_MUL_K:	/* A *= K */
 				emit_alu_K(MUL, K);
 				break;
 			case BPF_S_ALU_DIV_K:	/* A /= K */
 				emit_alu_K(MUL, K);
 				emit_read_y(r_A);
 				break;
 			case BPF_S_ALU_DIV_X:	/* A /= X; */
 				emit_cmpi(r_X, 0);
 				if (pc_ret0 > 0) {
 					t_offset = addrs[pc_ret0 - 1];
 #ifdef CONFIG_SPARC32
 					emit_branch(BE, t_offset + 20);
 #else
 					emit_branch(BE, t_offset + 8);
 #endif
 					emit_nop(); /* delay slot */
 				} else {
 					emit_branch_off(BNE, 16);
 					emit_nop();
 #ifdef CONFIG_SPARC32
 					emit_jump(cleanup_addr + 20);
 #else
 					emit_jump(cleanup_addr + 8);
 #endif
 					emit_clear(r_A);
 				}
 				emit_write_y(G0);
 #ifdef CONFIG_SPARC32
 				/* The Sparc v8 architecture requires
 				 * three instructions between a %y
 				 * register write and the first use.
 				 */
 				emit_nop();
 				emit_nop();
 				emit_nop();
 #endif
 				emit_alu_X(DIV);
 				break;
 			case BPF_S_ALU_NEG:
 				emit_neg();
 				break;
 			case BPF_S_RET_K:
 				if (!K) {
 					if (pc_ret0 == -1)
 						pc_ret0 = i;
 					emit_clear(r_A);
 				} else {
 					emit_loadimm(K, r_A);
 				}
 				/* Fallthrough */
 			case BPF_S_RET_A:
 				if (seen_or_pass0) {
 					if (i != flen - 1) {
 						emit_jump(cleanup_addr);
 						emit_nop();
 						break;
 					}
 					if (seen_or_pass0 & SEEN_MEM) {
 						unsigned int sz = BASE_STACKFRAME;
 						sz += BPF_MEMWORDS * sizeof(u32);
 						emit_release_stack(sz);
 					}
 				}
 				/* jmpl %r_saved_O7 + 8, %g0 */
 				emit_jmpl(r_saved_O7, 8, G0);
 				emit_reg_move(r_A, O0); /* delay slot */
 				break;
 			case BPF_S_MISC_TAX:
 				seen |= SEEN_XREG;
 				emit_reg_move(r_A, r_X);
 				break;
 			case BPF_S_MISC_TXA:
 				seen |= SEEN_XREG;
 				emit_reg_move(r_X, r_A);
 				break;
 			case BPF_S_ANC_CPU:
 				emit_load_cpu(r_A);
 				break;
 			case BPF_S_ANC_PROTOCOL:
 				emit_skb_load16(protocol, r_A);
 				break;
 #if 0
 				/* GCC won't let us take the address of
 				 * a bit field even though we very much
 				 * know what we are doing here.
 				 */
 			case BPF_S_ANC_PKTTYPE:
 				__emit_skb_load8(pkt_type, r_A);
 				emit_alu_K(SRL, 5);
 				break;
 #endif
 			case BPF_S_ANC_IFINDEX:
 				emit_skb_loadptr(dev, r_A);
 				emit_cmpi(r_A, 0);
 				emit_branch(BNE_PTR, cleanup_addr + 4);
 				emit_nop();
 				emit_load32(r_A, struct net_device, ifindex, r_A);
 				break;
 			case BPF_S_ANC_MARK:
 				emit_skb_load32(mark, r_A);
 				break;
 			case BPF_S_ANC_QUEUE:
 				emit_skb_load16(queue_mapping, r_A);
 				break;
 			case BPF_S_ANC_HATYPE:
 				emit_skb_loadptr(dev, r_A);
 				emit_cmpi(r_A, 0);
 				emit_branch(BNE_PTR, cleanup_addr + 4);
 				emit_nop();
 				emit_load16(r_A, struct net_device, type, r_A);
 				break;
 			case BPF_S_ANC_RXHASH:
 				emit_skb_load32(rxhash, r_A);
 				break;

 			case BPF_S_LD_IMM:
 				emit_loadimm(K, r_A);
 				break;
 			case BPF_S_LDX_IMM:
 				emit_loadimm(K, r_X);
 				break;
 			case BPF_S_LD_MEM:
 				emit_ldmem(K * 4, r_A);
 				break;
 			case BPF_S_LDX_MEM:
 				emit_ldmem(K * 4, r_X);
 				break;
 			case BPF_S_ST:
 				emit_stmem(K * 4, r_A);
 				break;
 			case BPF_S_STX:
 				emit_stmem(K * 4, r_X);
 				break;

 #define CHOOSE_LOAD_FUNC(K, func) \
 	((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset)

 			case BPF_S_LD_W_ABS:
 				func = CHOOSE_LOAD_FUNC(K, bpf_jit_load_word);
 common_load:			seen |= SEEN_DATAREF;
 				emit_loadimm(K, r_OFF);
 				emit_call(func);
 				break;
 			case BPF_S_LD_H_ABS:
 				func = CHOOSE_LOAD_FUNC(K, bpf_jit_load_half);
 				goto common_load;
 			case BPF_S_LD_B_ABS:
 				func = CHOOSE_LOAD_FUNC(K, bpf_jit_load_byte);
 				goto common_load;
 			case BPF_S_LDX_B_MSH:
 				func = CHOOSE_LOAD_FUNC(K, bpf_jit_load_byte_msh);
 				goto common_load;
 			case BPF_S_LD_W_IND:
 				func = bpf_jit_load_word;
 common_load_ind:		seen |= SEEN_DATAREF | SEEN_XREG;
 				if (K) {
 					if (is_simm13(K)) {
 						emit_addi(r_X, K, r_OFF);
 					} else {
 						emit_loadimm(K, r_TMP);
 						emit_add(r_X, r_TMP, r_OFF);
 					}
 				} else {
 					emit_reg_move(r_X, r_OFF);
 				}
 				emit_call(func);
 				break;
 			case BPF_S_LD_H_IND:
 				func = bpf_jit_load_half;
 				goto common_load_ind;
 			case BPF_S_LD_B_IND:
 				func = bpf_jit_load_byte;
 				goto common_load_ind;
 			case BPF_S_JMP_JA:
 				emit_jump(addrs[i + K]);
 				emit_nop();
 				break;

 #define COND_SEL(CODE, TOP, FOP)	\
 	case CODE:			\
 		t_op = TOP;		\
 		f_op = FOP;		\
 		goto cond_branch

 			COND_SEL(BPF_S_JMP_JGT_K, BGU, BLEU);
 			COND_SEL(BPF_S_JMP_JGE_K, BGEU, BLU);
 			COND_SEL(BPF_S_JMP_JEQ_K, BE, BNE);
 			COND_SEL(BPF_S_JMP_JSET_K, BNE, BE);
 			COND_SEL(BPF_S_JMP_JGT_X, BGU, BLEU);
 			COND_SEL(BPF_S_JMP_JGE_X, BGEU, BLU);
 			COND_SEL(BPF_S_JMP_JEQ_X, BE, BNE);
 			COND_SEL(BPF_S_JMP_JSET_X, BNE, BE);

 cond_branch:			f_offset = addrs[i + filter[i].jf];
 				t_offset = addrs[i + filter[i].jt];

 				/* same targets, can avoid doing the test :) */
 				if (filter[i].jt == filter[i].jf) {
 					emit_jump(t_offset);
 					emit_nop();
 					break;
 				}

 				switch (filter[i].code) {
 				case BPF_S_JMP_JGT_X:
 				case BPF_S_JMP_JGE_X:
 				case BPF_S_JMP_JEQ_X:
 					seen |= SEEN_XREG;
 					emit_cmp(r_A, r_X);
 					break;
 				case BPF_S_JMP_JSET_X:
 					seen |= SEEN_XREG;
 					emit_btst(r_A, r_X);
 					break;
 				case BPF_S_JMP_JEQ_K:
 				case BPF_S_JMP_JGT_K:
 				case BPF_S_JMP_JGE_K:
 					if (is_simm13(K)) {
 						emit_cmpi(r_A, K);
 					} else {
 						emit_loadimm(K, r_TMP);
 						emit_cmp(r_A, r_TMP);
 					}
 					break;
 				case BPF_S_JMP_JSET_K:
 					if (is_simm13(K)) {
 						emit_btsti(r_A, K);
 					} else {
 						emit_loadimm(K, r_TMP);
 						emit_btst(r_A, r_TMP);
 					}
 					break;
 				}
 				if (filter[i].jt != 0) {
 					if (filter[i].jf)
 						t_offset += 8;
 					emit_branch(t_op, t_offset);
 					emit_nop(); /* delay slot */
 					if (filter[i].jf) {
 						emit_jump(f_offset);
 						emit_nop();
 					}
 					break;
 				}
 				emit_branch(f_op, f_offset);
 				emit_nop(); /* delay slot */
 				break;

 			default:
 				/* hmm, too complex filter, give up with jit compiler */
 				goto out;
 			}
 			ilen = (void *) prog - (void *) temp;
 			if (image) {
 				if (unlikely(proglen + ilen > oldproglen)) {
 					pr_err("bpb_jit_compile fatal error\n");
 					kfree(addrs);
 					module_free(NULL, image);
 					return;
 				}
 				memcpy(image + proglen, temp, ilen);
 			}
 			proglen += ilen;
 			addrs[i] = proglen;
 			prog = temp;
 		}
 		/* last bpf instruction is always a RET :
 		 * use it to give the cleanup instruction(s) addr
 		 */
 		cleanup_addr = proglen - 8; /* jmpl; mov r_A,%o0; */
 		if (seen_or_pass0 & SEEN_MEM)
 			cleanup_addr -= 4; /* add %sp, X, %sp; */

 		if (image) {
 			if (proglen != oldproglen)
 				pr_err("bpb_jit_compile proglen=%u != oldproglen=%u\n",
 				       proglen, oldproglen);
 			break;
 		}
 		if (proglen == oldproglen) {
 			image = module_alloc(max_t(unsigned int,
 						   proglen,
 						   sizeof(struct work_struct)));
 			if (!image)
 				goto out;
 		}
 		oldproglen = proglen;
 	}

 	if (bpf_jit_enable > 1)
 		pr_err("flen=%d proglen=%u pass=%d image=%p\n",
 		       flen, proglen, pass, image);

 	if (image) {
 		if (bpf_jit_enable > 1)
 			print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_ADDRESS,
 				       16, 1, image, proglen, false);
 		bpf_flush_icache(image, image + proglen);
 		fp->bpf_func = (void *)image;
 	}
 out:
 	kfree(addrs);
 	return;
 }

 static void jit_free_defer(struct work_struct *arg)
 {
 	module_free(NULL, arg);
 }

 /* run from softirq, we must use a work_struct to call
  * module_free() from process context
  */
 void bpf_jit_free(struct sk_filter *fp)
 {
 	if (fp->bpf_func != sk_run_filter) {
 		struct work_struct *work = (struct work_struct *)fp->bpf_func;

 		INIT_WORK(work, jit_free_defer);
 		schedule_work(work);
 	}
 }
	#include <linux/moduleloader.h>
	#include <linux/workqueue.h>
	#include <linux/netdevice.h>
	#include <linux/filter.h>
	#include <linux/cache.h>

	#include <asm/cacheflush.h>
	#include <asm/ptrace.h>

	#include "bpf_jit.h"

	int bpf_jit_enable __read_mostly;

	static inline bool is_simm13(unsigned int value)
	{
	return value + 0x1000 < 0x2000;
	}

	static void bpf_flush_icache(void start_, void end_)
	{
	#ifdef CONFIG_SPARC64
	/* Cheetah's I-cache is fully coherent. */
	if (tlb_type == spitfire) {
	unsigned long start = (unsigned long) start_;
	unsigned long end = (unsigned long) end_;

	start &= ~7UL;
	end = (end + 7UL) & ~7UL;
	while (start < end) {
	flushi(start);
	start += 32;
	}
	}
	#endif
	}

	#define SEEN_DATAREF 1 /* might call external helpers */
	#define SEEN_XREG 2 /* ebx is used */
	#define SEEN_MEM 4 /* use mem[] for temporary storage */

	#define S13(X) ((X) & 0x1fff)
	#define IMMED 0x00002000
	#define RD(X) ((X) << 25)
	#define RS1(X) ((X) << 14)
	#define RS2(X) ((X))
	#define OP(X) ((X) << 30)
	#define OP2(X) ((X) << 22)
	#define OP3(X) ((X) << 19)
	#define COND(X) ((X) << 25)
	#define F1(X) OP(X)
	#define F2(X, Y) (OP(X) \| OP2(Y))
	#define F3(X, Y) (OP(X) \| OP3(Y))

	#define CONDN COND(0x0)
	#define CONDE COND(0x1)
	#define CONDLE COND(0x2)
	#define CONDL COND(0x3)
	#define CONDLEU COND(0x4)
	#define CONDCS COND(0x5)
	#define CONDNEG COND(0x6)
	#define CONDVC COND(0x7)
	#define CONDA COND(0x8)
	#define CONDNE COND(0x9)
	#define CONDG COND(0xa)
	#define CONDGE COND(0xb)
	#define CONDGU COND(0xc)
	#define CONDCC COND(0xd)
	#define CONDPOS COND(0xe)
	#define CONDVS COND(0xf)

	#define CONDGEU CONDCC
	#define CONDLU CONDCS

	#define WDISP22(X) (((X) >> 2) & 0x3fffff)

	#define BA (F2(0, 2) \| CONDA)
	#define BGU (F2(0, 2) \| CONDGU)
	#define BLEU (F2(0, 2) \| CONDLEU)
	#define BGEU (F2(0, 2) \| CONDGEU)
	#define BLU (F2(0, 2) \| CONDLU)
	#define BE (F2(0, 2) \| CONDE)
	#define BNE (F2(0, 2) \| CONDNE)

	#ifdef CONFIG_SPARC64
	#define BNE_PTR (F2(0, 1) \| CONDNE \| (2 << 20))
	#else
	#define BNE_PTR BNE
	#endif

	#define SETHI(K, REG) \
	(F2(0, 0x4) \| RD(REG) \| (((K) >> 10) & 0x3fffff))
	#define OR_LO(K, REG) \
	(F3(2, 0x02) \| IMMED \| RS1(REG) \| ((K) & 0x3ff) \| RD(REG))

	#define ADD F3(2, 0x00)
	#define AND F3(2, 0x01)
	#define ANDCC F3(2, 0x11)
	#define OR F3(2, 0x02)
	#define SUB F3(2, 0x04)
	#define SUBCC F3(2, 0x14)
	#define MUL F3(2, 0x0a) /* umul */
	#define DIV F3(2, 0x0e) /* udiv */
	#define SLL F3(2, 0x25)
	#define SRL F3(2, 0x26)
	#define JMPL F3(2, 0x38)
	#define CALL F1(1)
	#define BR F2(0, 0x01)
	#define RD_Y F3(2, 0x28)
	#define WR_Y F3(2, 0x30)

	#define LD32 F3(3, 0x00)
	#define LD8 F3(3, 0x01)
	#define LD16 F3(3, 0x02)
	#define LD64 F3(3, 0x0b)
	#define ST32 F3(3, 0x04)

	#ifdef CONFIG_SPARC64
	#define LDPTR LD64
	#define BASE_STACKFRAME 176
	#else
	#define LDPTR LD32
	#define BASE_STACKFRAME 96
	#endif

	#define LD32I (LD32 \| IMMED)
	#define LD8I (LD8 \| IMMED)
	#define LD16I (LD16 \| IMMED)
	#define LD64I (LD64 \| IMMED)
	#define LDPTRI (LDPTR \| IMMED)
	#define ST32I (ST32 \| IMMED)

	#define emit_nop() \
	do { \
	*prog++ = SETHI(0, G0); \
	} while (0)

	#define emit_neg() \
	do { /* sub %g0, r_A, r_A */ \
	*prog++ = SUB \| RS1(G0) \| RS2(r_A) \| RD(r_A); \
	} while (0)

	#define emit_reg_move(FROM, TO) \
	do { /* or %g0, FROM, TO */ \
	*prog++ = OR \| RS1(G0) \| RS2(FROM) \| RD(TO); \
	} while (0)

	#define emit_clear(REG) \
	do { /* or %g0, %g0, REG */ \
	*prog++ = OR \| RS1(G0) \| RS2(G0) \| RD(REG); \
	} while (0)

	#define emit_set_const(K, REG) \
	do { /* sethi %hi(K), REG */ \
	*prog++ = SETHI(K, REG); \
	/* or REG, %lo(K), REG */ \
	*prog++ = OR_LO(K, REG); \
	} while (0)

	/* Emit
	*
	* OP r_A, r_X, r_A
	*/
	#define emit_alu_X(OPCODE) \
	do { \
	seen \|= SEEN_XREG; \
	*prog++ = OPCODE \| RS1(r_A) \| RS2(r_X) \| RD(r_A); \
	} while (0)

	/* Emit either:
	*
	* OP r_A, K, r_A
	*
	* or
	*
	* sethi %hi(K), r_TMP
	* or r_TMP, %lo(K), r_TMP
	* OP r_A, r_TMP, r_A
	*
	* depending upon whether K fits in a signed 13-bit
	* immediate instruction field. Emit nothing if K
	* is zero.
	*/
	#define emit_alu_K(OPCODE, K) \
	do { \
	if (K) { \
	unsigned int _insn = OPCODE; \
	_insn \|= RS1(r_A) \| RD(r_A); \
	if (is_simm13(K)) { \
	*prog++ = _insn \| IMMED \| S13(K); \
	} else { \
	emit_set_const(K, r_TMP); \
	*prog++ = _insn \| RS2(r_TMP); \
	} \
	} \
	} while (0)

	#define emit_loadimm(K, DEST) \
	do { \
	if (is_simm13(K)) { \
	/* or %g0, K, DEST */ \
	*prog++ = OR \| IMMED \| RS1(G0) \| S13(K) \| RD(DEST); \
	} else { \
	emit_set_const(K, DEST); \
	} \
	} while (0)

	#define emit_loadptr(BASE, STRUCT, FIELD, DEST) \
	do { unsigned int _off = offsetof(STRUCT, FIELD); \
	BUILD_BUG_ON(FIELD_SIZEOF(STRUCT, FIELD) != sizeof(void *)); \
	*prog++ = LDPTRI \| RS1(BASE) \| S13(_off) \| RD(DEST); \
	} while (0)

	#define emit_load32(BASE, STRUCT, FIELD, DEST) \
	do { unsigned int _off = offsetof(STRUCT, FIELD); \
	BUILD_BUG_ON(FIELD_SIZEOF(STRUCT, FIELD) != sizeof(u32)); \
	*prog++ = LD32I \| RS1(BASE) \| S13(_off) \| RD(DEST); \
	} while (0)

	#define emit_load16(BASE, STRUCT, FIELD, DEST) \
	do { unsigned int _off = offsetof(STRUCT, FIELD); \
	BUILD_BUG_ON(FIELD_SIZEOF(STRUCT, FIELD) != sizeof(u16)); \
	*prog++ = LD16I \| RS1(BASE) \| S13(_off) \| RD(DEST); \
	} while (0)

	#define __emit_load8(BASE, STRUCT, FIELD, DEST) \
	do { unsigned int _off = offsetof(STRUCT, FIELD); \
	*prog++ = LD8I \| RS1(BASE) \| S13(_off) \| RD(DEST); \
	} while (0)

	#define emit_load8(BASE, STRUCT, FIELD, DEST) \
	do { BUILD_BUG_ON(FIELD_SIZEOF(STRUCT, FIELD) != sizeof(u8)); \
	__emit_load8(BASE, STRUCT, FIELD, DEST); \
	} while (0)

	#define emit_ldmem(OFF, DEST) \
	do { *prog++ = LD32I \| RS1(FP) \| S13(-(OFF)) \| RD(DEST); \
	} while (0)

	#define emit_stmem(OFF, SRC) \
	do { *prog++ = LD32I \| RS1(FP) \| S13(-(OFF)) \| RD(SRC); \
	} while (0)

	#ifdef CONFIG_SMP
	#ifdef CONFIG_SPARC64
	#define emit_load_cpu(REG) \
	emit_load16(G6, struct thread_info, cpu, REG)
	#else
	#define emit_load_cpu(REG) \
	emit_load32(G6, struct thread_info, cpu, REG)
	#endif
	#else
	#define emit_load_cpu(REG) emit_clear(REG)
	#endif

	#define emit_skb_loadptr(FIELD, DEST) \
	emit_loadptr(r_SKB, struct sk_buff, FIELD, DEST)
	#define emit_skb_load32(FIELD, DEST) \
	emit_load32(r_SKB, struct sk_buff, FIELD, DEST)
	#define emit_skb_load16(FIELD, DEST) \
	emit_load16(r_SKB, struct sk_buff, FIELD, DEST)
	#define __emit_skb_load8(FIELD, DEST) \
	__emit_load8(r_SKB, struct sk_buff, FIELD, DEST)
	#define emit_skb_load8(FIELD, DEST) \
	emit_load8(r_SKB, struct sk_buff, FIELD, DEST)

	#define emit_jmpl(BASE, IMM_OFF, LREG) \
	*prog++ = (JMPL \| IMMED \| RS1(BASE) \| S13(IMM_OFF) \| RD(LREG))

	#define emit_call(FUNC) \
	do { void *_here = image + addrs[i] - 8; \
	unsigned int _off = (void *)(FUNC) - _here; \
	*prog++ = CALL \| (((_off) >> 2) & 0x3fffffff); \
	emit_nop(); \
	} while (0)

	#define emit_branch(BR_OPC, DEST) \
	do { unsigned int _here = addrs[i] - 8; \
	*prog++ = BR_OPC \| WDISP22((DEST) - _here); \
	} while (0)

	#define emit_branch_off(BR_OPC, OFF) \
	do { *prog++ = BR_OPC \| WDISP22(OFF); \
	} while (0)

	#define emit_jump(DEST) emit_branch(BA, DEST)

	#define emit_read_y(REG) *prog++ = RD_Y \| RD(REG)
	#define emit_write_y(REG) *prog++ = WR_Y \| IMMED \| RS1(REG) \| S13(0)

	#define emit_cmp(R1, R2) \
	*prog++ = (SUBCC \| RS1(R1) \| RS2(R2) \| RD(G0))

	#define emit_cmpi(R1, IMM) \
	*prog++ = (SUBCC \| IMMED \| RS1(R1) \| S13(IMM) \| RD(G0));

	#define emit_btst(R1, R2) \
	*prog++ = (ANDCC \| RS1(R1) \| RS2(R2) \| RD(G0))

	#define emit_btsti(R1, IMM) \
	*prog++ = (ANDCC \| IMMED \| RS1(R1) \| S13(IMM) \| RD(G0));

	#define emit_sub(R1, R2, R3) \
	*prog++ = (SUB \| RS1(R1) \| RS2(R2) \| RD(R3))

	#define emit_subi(R1, IMM, R3) \
	*prog++ = (SUB \| IMMED \| RS1(R1) \| S13(IMM) \| RD(R3))

	#define emit_add(R1, R2, R3) \
	*prog++ = (ADD \| RS1(R1) \| RS2(R2) \| RD(R3))

	#define emit_addi(R1, IMM, R3) \
	*prog++ = (ADD \| IMMED \| RS1(R1) \| S13(IMM) \| RD(R3))

	#define emit_alloc_stack(SZ) \
	*prog++ = (SUB \| IMMED \| RS1(SP) \| S13(SZ) \| RD(SP))

	#define emit_release_stack(SZ) \
	*prog++ = (ADD \| IMMED \| RS1(SP) \| S13(SZ) \| RD(SP))

	/* A note about branch offset calculations. The addrs[] array,
	* indexed by BPF instruction, records the address after all the
	* sparc instructions emitted for that BPF instruction.
	*
	* The most common case is to emit a branch at the end of such
	* a code sequence. So this would be two instructions, the
	* branch and it's delay slot.
	*
	* Therefore by default the branch emitters calculate the branch
	* offset field as:
	*
	* destination - (addrs[i] - 8)
	*
	* This "addrs[i] - 8" is the address of the branch itself or
	* what "." would be in assembler notation. The "8" part is
	* how we take into consideration the branch and it's delay
	* slot mentioned above.
	*
	* Sometimes we need to emit a branch earlier in the code
	* sequence. And in these situations we adjust "destination"
	* to accomodate this difference. For example, if we needed
	* to emit a branch (and it's delay slot) right before the
	* final instruction emitted for a BPF opcode, we'd use
	* "destination + 4" instead of just plain "destination" above.
	*
	* This is why you see all of these funny emit_branch() and
	* emit_jump() calls with adjusted offsets.
	*/

	void bpf_jit_compile(struct sk_filter *fp)
	{
	unsigned int cleanup_addr, proglen, oldproglen = 0;
	u32 temp[8], prog, func, seen = 0, pass;
	const struct sock_filter *filter = fp->insns;
	int i, flen = fp->len, pc_ret0 = -1;
	unsigned int *addrs;
	void *image;

	if (!bpf_jit_enable)
	return;

	addrs = kmalloc(flen * sizeof(*addrs), GFP_KERNEL);
	if (addrs == NULL)
	return;

	/* Before first pass, make a rough estimation of addrs[]
	* each bpf instruction is translated to less than 64 bytes
	*/
	for (proglen = 0, i = 0; i < flen; i++) {
	proglen += 64;
	addrs[i] = proglen;
	}
	cleanup_addr = proglen; /* epilogue address */
	image = NULL;
	for (pass = 0; pass < 10; pass++) {
	u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG \| SEEN_DATAREF \| SEEN_MEM) : seen;

	/* no prologue/epilogue for trivial filters (RET something) */
	proglen = 0;
	prog = temp;

	/* Prologue */
	if (seen_or_pass0) {
	if (seen_or_pass0 & SEEN_MEM) {
	unsigned int sz = BASE_STACKFRAME;
	sz += BPF_MEMWORDS * sizeof(u32);
	emit_alloc_stack(sz);
	}

	/* Make sure we dont leek kernel memory. */
	if (seen_or_pass0 & SEEN_XREG)
	emit_clear(r_X);

	/* If this filter needs to access skb data,
	* load %o4 and %o5 with:
	* %o4 = skb->len - skb->data_len
	* %o5 = skb->data
	* And also back up %o7 into r_saved_O7 so we can
	* invoke the stubs using 'call'.
	*/
	if (seen_or_pass0 & SEEN_DATAREF) {
	emit_load32(r_SKB, struct sk_buff, len, r_HEADLEN);
	emit_load32(r_SKB, struct sk_buff, data_len, r_TMP);
	emit_sub(r_HEADLEN, r_TMP, r_HEADLEN);
	emit_loadptr(r_SKB, struct sk_buff, data, r_SKB_DATA);
	}
	}
	emit_reg_move(O7, r_saved_O7);

	switch (filter[0].code) {
	case BPF_S_RET_K:
	case BPF_S_LD_W_LEN:
	case BPF_S_ANC_PROTOCOL:
	case BPF_S_ANC_PKTTYPE:
	case BPF_S_ANC_IFINDEX:
	case BPF_S_ANC_MARK:
	case BPF_S_ANC_RXHASH:
	case BPF_S_ANC_CPU:
	case BPF_S_ANC_QUEUE:
	case BPF_S_LD_W_ABS:
	case BPF_S_LD_H_ABS:
	case BPF_S_LD_B_ABS:
	/* The first instruction sets the A register (or is
	* a "RET 'constant'")
	*/
	break;
	default:
	/* Make sure we dont leak kernel information to the
	* user.
	*/
	emit_clear(r_A); /* A = 0 */
	}

	for (i = 0; i < flen; i++) {
	unsigned int K = filter[i].k;
	unsigned int t_offset;
	unsigned int f_offset;
	u32 t_op, f_op;
	int ilen;

	switch (filter[i].code) {
	case BPF_S_ALU_ADD_X: /* A += X; */
	emit_alu_X(ADD);
	break;
	case BPF_S_ALU_ADD_K: /* A += K; */
	emit_alu_K(ADD, K);
	break;
	case BPF_S_ALU_SUB_X: /* A -= X; */
	emit_alu_X(SUB);
	break;
	case BPF_S_ALU_SUB_K: /* A -= K */
	emit_alu_K(SUB, K);
	break;
	case BPF_S_ALU_AND_X: /* A &= X */
	emit_alu_X(AND);
	break;
	case BPF_S_ALU_AND_K: /* A &= K */
	emit_alu_K(AND, K);
	break;
	case BPF_S_ALU_OR_X: /* A \|= X */
	emit_alu_X(OR);
	break;
	case BPF_S_ALU_OR_K: /* A \|= K */
	emit_alu_K(OR, K);
	break;
	case BPF_S_ALU_LSH_X: /* A <<= X */
	emit_alu_X(SLL);
	break;
	case BPF_S_ALU_LSH_K: /* A <<= K */
	emit_alu_K(SLL, K);
	break;
	case BPF_S_ALU_RSH_X: /* A >>= X */
	emit_alu_X(SRL);
	break;
	case BPF_S_ALU_RSH_K: /* A >>= K */
	emit_alu_K(SRL, K);
	break;
	case BPF_S_ALU_MUL_X: /* A = X; /
	emit_alu_X(MUL);
	break;
	case BPF_S_ALU_MUL_K: /* A = K /
	emit_alu_K(MUL, K);
	break;
	case BPF_S_ALU_DIV_K: /* A /= K */
	emit_alu_K(MUL, K);
	emit_read_y(r_A);
	break;
	case BPF_S_ALU_DIV_X: /* A /= X; */
	emit_cmpi(r_X, 0);
	if (pc_ret0 > 0) {
	t_offset = addrs[pc_ret0 - 1];
	#ifdef CONFIG_SPARC32
	emit_branch(BE, t_offset + 20);
	#else
	emit_branch(BE, t_offset + 8);
	#endif
	emit_nop(); /* delay slot */
	} else {
	emit_branch_off(BNE, 16);
	emit_nop();
	#ifdef CONFIG_SPARC32
	emit_jump(cleanup_addr + 20);
	#else
	emit_jump(cleanup_addr + 8);
	#endif
	emit_clear(r_A);
	}
	emit_write_y(G0);
	#ifdef CONFIG_SPARC32
	/* The Sparc v8 architecture requires
	* three instructions between a %y
	* register write and the first use.
	*/
	emit_nop();
	emit_nop();
	emit_nop();
	#endif
	emit_alu_X(DIV);
	break;
	case BPF_S_ALU_NEG:
	emit_neg();
	break;
	case BPF_S_RET_K:
	if (!K) {
	if (pc_ret0 == -1)
	pc_ret0 = i;
	emit_clear(r_A);
	} else {
	emit_loadimm(K, r_A);
	}
	/* Fallthrough */
	case BPF_S_RET_A:
	if (seen_or_pass0) {
	if (i != flen - 1) {
	emit_jump(cleanup_addr);
	emit_nop();
	break;
	}
	if (seen_or_pass0 & SEEN_MEM) {
	unsigned int sz = BASE_STACKFRAME;
	sz += BPF_MEMWORDS * sizeof(u32);
	emit_release_stack(sz);
	}
	}
	/* jmpl %r_saved_O7 + 8, %g0 */
	emit_jmpl(r_saved_O7, 8, G0);
	emit_reg_move(r_A, O0); /* delay slot */
	break;
	case BPF_S_MISC_TAX:
	seen \|= SEEN_XREG;
	emit_reg_move(r_A, r_X);
	break;
	case BPF_S_MISC_TXA:
	seen \|= SEEN_XREG;
	emit_reg_move(r_X, r_A);
	break;
	case BPF_S_ANC_CPU:
	emit_load_cpu(r_A);
	break;
	case BPF_S_ANC_PROTOCOL:
	emit_skb_load16(protocol, r_A);
	break;
	#if 0
	/* GCC won't let us take the address of
	* a bit field even though we very much
	* know what we are doing here.
	*/
	case BPF_S_ANC_PKTTYPE:
	__emit_skb_load8(pkt_type, r_A);
	emit_alu_K(SRL, 5);
	break;
	#endif
	case BPF_S_ANC_IFINDEX:
	emit_skb_loadptr(dev, r_A);
	emit_cmpi(r_A, 0);
	emit_branch(BNE_PTR, cleanup_addr + 4);
	emit_nop();
	emit_load32(r_A, struct net_device, ifindex, r_A);
	break;
	case BPF_S_ANC_MARK:
	emit_skb_load32(mark, r_A);
	break;
	case BPF_S_ANC_QUEUE:
	emit_skb_load16(queue_mapping, r_A);
	break;
	case BPF_S_ANC_HATYPE:
	emit_skb_loadptr(dev, r_A);
	emit_cmpi(r_A, 0);
	emit_branch(BNE_PTR, cleanup_addr + 4);
	emit_nop();
	emit_load16(r_A, struct net_device, type, r_A);
	break;
	case BPF_S_ANC_RXHASH:
	emit_skb_load32(rxhash, r_A);
	break;

	case BPF_S_LD_IMM:
	emit_loadimm(K, r_A);
	break;
	case BPF_S_LDX_IMM:
	emit_loadimm(K, r_X);
	break;
	case BPF_S_LD_MEM:
	emit_ldmem(K * 4, r_A);
	break;
	case BPF_S_LDX_MEM:
	emit_ldmem(K * 4, r_X);
	break;
	case BPF_S_ST:
	emit_stmem(K * 4, r_A);
	break;
	case BPF_S_STX:
	emit_stmem(K * 4, r_X);
	break;

	#define CHOOSE_LOAD_FUNC(K, func) \
	((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset)

	case BPF_S_LD_W_ABS:
	func = CHOOSE_LOAD_FUNC(K, bpf_jit_load_word);
	common_load: seen \|= SEEN_DATAREF;
	emit_loadimm(K, r_OFF);
	emit_call(func);
	break;
	case BPF_S_LD_H_ABS:
	func = CHOOSE_LOAD_FUNC(K, bpf_jit_load_half);
	goto common_load;
	case BPF_S_LD_B_ABS:
	func = CHOOSE_LOAD_FUNC(K, bpf_jit_load_byte);
	goto common_load;
	case BPF_S_LDX_B_MSH:
	func = CHOOSE_LOAD_FUNC(K, bpf_jit_load_byte_msh);
	goto common_load;
	case BPF_S_LD_W_IND:
	func = bpf_jit_load_word;
	common_load_ind: seen \|= SEEN_DATAREF \| SEEN_XREG;
	if (K) {
	if (is_simm13(K)) {
	emit_addi(r_X, K, r_OFF);
	} else {
	emit_loadimm(K, r_TMP);
	emit_add(r_X, r_TMP, r_OFF);
	}
	} else {
	emit_reg_move(r_X, r_OFF);
	}
	emit_call(func);
	break;
	case BPF_S_LD_H_IND:
	func = bpf_jit_load_half;
	goto common_load_ind;
	case BPF_S_LD_B_IND:
	func = bpf_jit_load_byte;
	goto common_load_ind;
	case BPF_S_JMP_JA:
	emit_jump(addrs[i + K]);
	emit_nop();
	break;

	#define COND_SEL(CODE, TOP, FOP) \
	case CODE: \
	t_op = TOP; \
	f_op = FOP; \
	goto cond_branch

	COND_SEL(BPF_S_JMP_JGT_K, BGU, BLEU);
	COND_SEL(BPF_S_JMP_JGE_K, BGEU, BLU);
	COND_SEL(BPF_S_JMP_JEQ_K, BE, BNE);
	COND_SEL(BPF_S_JMP_JSET_K, BNE, BE);
	COND_SEL(BPF_S_JMP_JGT_X, BGU, BLEU);
	COND_SEL(BPF_S_JMP_JGE_X, BGEU, BLU);
	COND_SEL(BPF_S_JMP_JEQ_X, BE, BNE);
	COND_SEL(BPF_S_JMP_JSET_X, BNE, BE);

	cond_branch: f_offset = addrs[i + filter[i].jf];
	t_offset = addrs[i + filter[i].jt];

	/* same targets, can avoid doing the test :) */
	if (filter[i].jt == filter[i].jf) {
	emit_jump(t_offset);
	emit_nop();
	break;
	}

	switch (filter[i].code) {
	case BPF_S_JMP_JGT_X:
	case BPF_S_JMP_JGE_X:
	case BPF_S_JMP_JEQ_X:
	seen \|= SEEN_XREG;
	emit_cmp(r_A, r_X);
	break;
	case BPF_S_JMP_JSET_X:
	seen \|= SEEN_XREG;
	emit_btst(r_A, r_X);
	break;
	case BPF_S_JMP_JEQ_K:
	case BPF_S_JMP_JGT_K:
	case BPF_S_JMP_JGE_K:
	if (is_simm13(K)) {
	emit_cmpi(r_A, K);
	} else {
	emit_loadimm(K, r_TMP);
	emit_cmp(r_A, r_TMP);
	}
	break;
	case BPF_S_JMP_JSET_K:
	if (is_simm13(K)) {
	emit_btsti(r_A, K);
	} else {
	emit_loadimm(K, r_TMP);
	emit_btst(r_A, r_TMP);
	}
	break;
	}
	if (filter[i].jt != 0) {
	if (filter[i].jf)
	t_offset += 8;
	emit_branch(t_op, t_offset);
	emit_nop(); /* delay slot */
	if (filter[i].jf) {
	emit_jump(f_offset);
	emit_nop();
	}
	break;
	}
	emit_branch(f_op, f_offset);
	emit_nop(); /* delay slot */
	break;

	default:
	/* hmm, too complex filter, give up with jit compiler */
	goto out;
	}
	ilen = (void ) prog - (void ) temp;
	if (image) {
	if (unlikely(proglen + ilen > oldproglen)) {
	pr_err("bpb_jit_compile fatal error\n");
	kfree(addrs);
	module_free(NULL, image);
	return;
	}
	memcpy(image + proglen, temp, ilen);
	}
	proglen += ilen;
	addrs[i] = proglen;
	prog = temp;
	}
	/* last bpf instruction is always a RET :
	* use it to give the cleanup instruction(s) addr
	*/
	cleanup_addr = proglen - 8; /* jmpl; mov r_A,%o0; */
	if (seen_or_pass0 & SEEN_MEM)
	cleanup_addr -= 4; /* add %sp, X, %sp; */

	if (image) {
	if (proglen != oldproglen)
	pr_err("bpb_jit_compile proglen=%u != oldproglen=%u\n",
	proglen, oldproglen);
	break;
	}
	if (proglen == oldproglen) {
	image = module_alloc(max_t(unsigned int,
	proglen,
	sizeof(struct work_struct)));
	if (!image)
	goto out;
	}
	oldproglen = proglen;
	}

	if (bpf_jit_enable > 1)
	pr_err("flen=%d proglen=%u pass=%d image=%p\n",
	flen, proglen, pass, image);

	if (image) {
	if (bpf_jit_enable > 1)
	print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_ADDRESS,
	16, 1, image, proglen, false);
	bpf_flush_icache(image, image + proglen);
	fp->bpf_func = (void *)image;
	}
	out:
	kfree(addrs);
	return;
	}

	static void jit_free_defer(struct work_struct *arg)
	{
	module_free(NULL, arg);
	}

	/* run from softirq, we must use a work_struct to call
	* module_free() from process context
	*/
	void bpf_jit_free(struct sk_filter *fp)
	{
	if (fp->bpf_func != sk_run_filter) {
	struct work_struct work = (struct work_struct )fp->bpf_func;

	INIT_WORK(work, jit_free_defer);
	schedule_work(work);
	}
	}