Exemplo n.º 1
0
/* Assemble the body code between the prologue & epilogue. */
static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
			      struct codegen_context *ctx,
			      unsigned int *addrs)
{
	const struct sock_filter *filter = fp->insns;
	int flen = fp->len;
	u8 *func;
	unsigned int true_cond;
	int i;

	/* Start of epilogue code */
	unsigned int exit_addr = addrs[flen];

	for (i = 0; i < flen; i++) {
		unsigned int K = filter[i].k;
		u16 code = bpf_anc_helper(&filter[i]);

		/*
		 * addrs[] maps a BPF bytecode address into a real offset from
		 * the start of the body code.
		 */
		addrs[i] = ctx->idx * 4;

		switch (code) {
			/*** ALU ops ***/
		case BPF_ALU | BPF_ADD | BPF_X: /* A += X; */
			ctx->seen |= SEEN_XREG;
			PPC_ADD(r_A, r_A, r_X);
			break;
		case BPF_ALU | BPF_ADD | BPF_K: /* A += K; */
			if (!K)
				break;
			PPC_ADDI(r_A, r_A, IMM_L(K));
			if (K >= 32768)
				PPC_ADDIS(r_A, r_A, IMM_HA(K));
			break;
		case BPF_ALU | BPF_SUB | BPF_X: /* A -= X; */
			ctx->seen |= SEEN_XREG;
			PPC_SUB(r_A, r_A, r_X);
			break;
		case BPF_ALU | BPF_SUB | BPF_K: /* A -= K */
			if (!K)
				break;
			PPC_ADDI(r_A, r_A, IMM_L(-K));
			if (K >= 32768)
				PPC_ADDIS(r_A, r_A, IMM_HA(-K));
			break;
		case BPF_ALU | BPF_MUL | BPF_X: /* A *= X; */
			ctx->seen |= SEEN_XREG;
			PPC_MUL(r_A, r_A, r_X);
			break;
		case BPF_ALU | BPF_MUL | BPF_K: /* A *= K */
			if (K < 32768)
				PPC_MULI(r_A, r_A, K);
			else {
				PPC_LI32(r_scratch1, K);
				PPC_MUL(r_A, r_A, r_scratch1);
			}
			break;
		case BPF_ALU | BPF_MOD | BPF_X: /* A %= X; */
			ctx->seen |= SEEN_XREG;
			PPC_CMPWI(r_X, 0);
			if (ctx->pc_ret0 != -1) {
				PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]);
			} else {
				PPC_BCC_SHORT(COND_NE, (ctx->idx*4)+12);
				PPC_LI(r_ret, 0);
				PPC_JMP(exit_addr);
			}
			PPC_DIVWU(r_scratch1, r_A, r_X);
			PPC_MUL(r_scratch1, r_X, r_scratch1);
			PPC_SUB(r_A, r_A, r_scratch1);
			break;
		case BPF_ALU | BPF_MOD | BPF_K: /* A %= K; */
			PPC_LI32(r_scratch2, K);
			PPC_DIVWU(r_scratch1, r_A, r_scratch2);
			PPC_MUL(r_scratch1, r_scratch2, r_scratch1);
			PPC_SUB(r_A, r_A, r_scratch1);
			break;
		case BPF_ALU | BPF_DIV | BPF_X: /* A /= X; */
			ctx->seen |= SEEN_XREG;
			PPC_CMPWI(r_X, 0);
			if (ctx->pc_ret0 != -1) {
				PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]);
			} else {
				/*
				 * Exit, returning 0; first pass hits here
				 * (longer worst-case code size).
				 */
				PPC_BCC_SHORT(COND_NE, (ctx->idx*4)+12);
				PPC_LI(r_ret, 0);
				PPC_JMP(exit_addr);
			}
			PPC_DIVWU(r_A, r_A, r_X);
			break;
		case BPF_ALU | BPF_DIV | BPF_K: /* A /= K */
			if (K == 1)
				break;
			PPC_LI32(r_scratch1, K);
			PPC_DIVWU(r_A, r_A, r_scratch1);
			break;
		case BPF_ALU | BPF_AND | BPF_X:
			ctx->seen |= SEEN_XREG;
			PPC_AND(r_A, r_A, r_X);
			break;
		case BPF_ALU | BPF_AND | BPF_K:
			if (!IMM_H(K))
				PPC_ANDI(r_A, r_A, K);
			else {
				PPC_LI32(r_scratch1, K);
				PPC_AND(r_A, r_A, r_scratch1);
			}
			break;
		case BPF_ALU | BPF_OR | BPF_X:
			ctx->seen |= SEEN_XREG;
			PPC_OR(r_A, r_A, r_X);
			break;
		case BPF_ALU | BPF_OR | BPF_K:
			if (IMM_L(K))
				PPC_ORI(r_A, r_A, IMM_L(K));
			if (K >= 65536)
				PPC_ORIS(r_A, r_A, IMM_H(K));
			break;
		case BPF_ANC | SKF_AD_ALU_XOR_X:
		case BPF_ALU | BPF_XOR | BPF_X: /* A ^= X */
			ctx->seen |= SEEN_XREG;
			PPC_XOR(r_A, r_A, r_X);
			break;
		case BPF_ALU | BPF_XOR | BPF_K: /* A ^= K */
			if (IMM_L(K))
				PPC_XORI(r_A, r_A, IMM_L(K));
			if (K >= 65536)
				PPC_XORIS(r_A, r_A, IMM_H(K));
			break;
		case BPF_ALU | BPF_LSH | BPF_X: /* A <<= X; */
			ctx->seen |= SEEN_XREG;
			PPC_SLW(r_A, r_A, r_X);
			break;
		case BPF_ALU | BPF_LSH | BPF_K:
			if (K == 0)
				break;
			else
				PPC_SLWI(r_A, r_A, K);
			break;
		case BPF_ALU | BPF_RSH | BPF_X: /* A >>= X; */
			ctx->seen |= SEEN_XREG;
			PPC_SRW(r_A, r_A, r_X);
			break;
		case BPF_ALU | BPF_RSH | BPF_K: /* A >>= K; */
			if (K == 0)
				break;
			else
				PPC_SRWI(r_A, r_A, K);
			break;
		case BPF_ALU | BPF_NEG:
			PPC_NEG(r_A, r_A);
			break;
		case BPF_RET | BPF_K:
			PPC_LI32(r_ret, K);
			if (!K) {
				if (ctx->pc_ret0 == -1)
					ctx->pc_ret0 = i;
			}
			/*
			 * If this isn't the very last instruction, branch to
			 * the epilogue if we've stuff to clean up.  Otherwise,
			 * if there's nothing to tidy, just return.  If we /are/
			 * the last instruction, we're about to fall through to
			 * the epilogue to return.
			 */
			if (i != flen - 1) {
				/*
				 * Note: 'seen' is properly valid only on pass
				 * #2.	Both parts of this conditional are the
				 * same instruction size though, meaning the
				 * first pass will still correctly determine the
				 * code size/addresses.
				 */
				if (ctx->seen)
					PPC_JMP(exit_addr);
				else
					PPC_BLR();
			}
			break;
		case BPF_RET | BPF_A:
			PPC_MR(r_ret, r_A);
			if (i != flen - 1) {
				if (ctx->seen)
					PPC_JMP(exit_addr);
				else
					PPC_BLR();
			}
			break;
		case BPF_MISC | BPF_TAX: /* X = A */
			PPC_MR(r_X, r_A);
			break;
		case BPF_MISC | BPF_TXA: /* A = X */
			ctx->seen |= SEEN_XREG;
			PPC_MR(r_A, r_X);
			break;

			/*** Constant loads/M[] access ***/
		case BPF_LD | BPF_IMM: /* A = K */
			PPC_LI32(r_A, K);
			break;
		case BPF_LDX | BPF_IMM: /* X = K */
			PPC_LI32(r_X, K);
			break;
		case BPF_LD | BPF_MEM: /* A = mem[K] */
			PPC_MR(r_A, r_M + (K & 0xf));
			ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
			break;
		case BPF_LDX | BPF_MEM: /* X = mem[K] */
			PPC_MR(r_X, r_M + (K & 0xf));
			ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
			break;
		case BPF_ST: /* mem[K] = A */
			PPC_MR(r_M + (K & 0xf), r_A);
			ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
			break;
		case BPF_STX: /* mem[K] = X */
			PPC_MR(r_M + (K & 0xf), r_X);
			ctx->seen |= SEEN_XREG | SEEN_MEM | (1<<(K & 0xf));
			break;
		case BPF_LD | BPF_W | BPF_LEN: /*	A = skb->len; */
			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
			PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff, len));
			break;
		case BPF_LDX | BPF_W | BPF_LEN: /* X = skb->len; */
			PPC_LWZ_OFFS(r_X, r_skb, offsetof(struct sk_buff, len));
			break;

			/*** Ancillary info loads ***/
		case BPF_ANC | SKF_AD_PROTOCOL: /* A = ntohs(skb->protocol); */
			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
						  protocol) != 2);
			PPC_NTOHS_OFFS(r_A, r_skb, offsetof(struct sk_buff,
							    protocol));
			break;
		case BPF_ANC | SKF_AD_IFINDEX:
			PPC_LD_OFFS(r_scratch1, r_skb, offsetof(struct sk_buff,
								dev));
			PPC_CMPDI(r_scratch1, 0);
			if (ctx->pc_ret0 != -1) {
				PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]);
			} else {
				/* Exit, returning 0; first pass hits here. */
				PPC_BCC_SHORT(COND_NE, (ctx->idx*4)+12);
				PPC_LI(r_ret, 0);
				PPC_JMP(exit_addr);
			}
			BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
						  ifindex) != 4);
			PPC_LWZ_OFFS(r_A, r_scratch1,
				     offsetof(struct net_device, ifindex));
			break;
		case BPF_ANC | SKF_AD_MARK:
			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
			PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
							  mark));
			break;
		case BPF_ANC | SKF_AD_RXHASH:
			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4);
			PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
							  hash));
			break;
		case BPF_ANC | SKF_AD_VLAN_TAG:
		case BPF_ANC | SKF_AD_VLAN_TAG_PRESENT:
			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
			BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000);

			PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
							  vlan_tci));
			if (code == (BPF_ANC | SKF_AD_VLAN_TAG)) {
				PPC_ANDI(r_A, r_A, ~VLAN_TAG_PRESENT);
			} else {
				PPC_ANDI(r_A, r_A, VLAN_TAG_PRESENT);
				PPC_SRWI(r_A, r_A, 12);
			}
			break;
		case BPF_ANC | SKF_AD_QUEUE:
			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
						  queue_mapping) != 2);
			PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
							  queue_mapping));
			break;
		case BPF_ANC | SKF_AD_CPU:
#ifdef CONFIG_SMP
			/*
			 * PACA ptr is r13:
			 * raw_smp_processor_id() = local_paca->paca_index
			 */
			BUILD_BUG_ON(FIELD_SIZEOF(struct paca_struct,
						  paca_index) != 2);
			PPC_LHZ_OFFS(r_A, 13,
				     offsetof(struct paca_struct, paca_index));
#else
			PPC_LI(r_A, 0);
#endif
			break;

			/*** Absolute loads from packet header/data ***/
		case BPF_LD | BPF_W | BPF_ABS:
			func = CHOOSE_LOAD_FUNC(K, sk_load_word);
			goto common_load;
		case BPF_LD | BPF_H | BPF_ABS:
			func = CHOOSE_LOAD_FUNC(K, sk_load_half);
			goto common_load;
		case BPF_LD | BPF_B | BPF_ABS:
			func = CHOOSE_LOAD_FUNC(K, sk_load_byte);
		common_load:
			/* Load from [K]. */
			ctx->seen |= SEEN_DATAREF;
			PPC_LI64(r_scratch1, func);
			PPC_MTLR(r_scratch1);
			PPC_LI32(r_addr, K);
			PPC_BLRL();
			/*
			 * Helper returns 'lt' condition on error, and an
			 * appropriate return value in r3
			 */
			PPC_BCC(COND_LT, exit_addr);
			break;

			/*** Indirect loads from packet header/data ***/
		case BPF_LD | BPF_W | BPF_IND:
			func = sk_load_word;
			goto common_load_ind;
		case BPF_LD | BPF_H | BPF_IND:
			func = sk_load_half;
			goto common_load_ind;
		case BPF_LD | BPF_B | BPF_IND:
			func = sk_load_byte;
		common_load_ind:
			/*
			 * Load from [X + K].  Negative offsets are tested for
			 * in the helper functions.
			 */
			ctx->seen |= SEEN_DATAREF | SEEN_XREG;
			PPC_LI64(r_scratch1, func);
			PPC_MTLR(r_scratch1);
			PPC_ADDI(r_addr, r_X, IMM_L(K));
			if (K >= 32768)
				PPC_ADDIS(r_addr, r_addr, IMM_HA(K));
			PPC_BLRL();
			/* If error, cr0.LT set */
			PPC_BCC(COND_LT, exit_addr);
			break;

		case BPF_LDX | BPF_B | BPF_MSH:
			func = CHOOSE_LOAD_FUNC(K, sk_load_byte_msh);
			goto common_load;
			break;

			/*** Jump and branches ***/
		case BPF_JMP | BPF_JA:
			if (K != 0)
				PPC_JMP(addrs[i + 1 + K]);
			break;

		case BPF_JMP | BPF_JGT | BPF_K:
		case BPF_JMP | BPF_JGT | BPF_X:
			true_cond = COND_GT;
			goto cond_branch;
		case BPF_JMP | BPF_JGE | BPF_K:
		case BPF_JMP | BPF_JGE | BPF_X:
			true_cond = COND_GE;
			goto cond_branch;
		case BPF_JMP | BPF_JEQ | BPF_K:
		case BPF_JMP | BPF_JEQ | BPF_X:
			true_cond = COND_EQ;
			goto cond_branch;
		case BPF_JMP | BPF_JSET | BPF_K:
		case BPF_JMP | BPF_JSET | BPF_X:
			true_cond = COND_NE;
			/* Fall through */
		cond_branch:
			/* same targets, can avoid doing the test :) */
			if (filter[i].jt == filter[i].jf) {
				if (filter[i].jt > 0)
					PPC_JMP(addrs[i + 1 + filter[i].jt]);
				break;
			}

			switch (code) {
			case BPF_JMP | BPF_JGT | BPF_X:
			case BPF_JMP | BPF_JGE | BPF_X:
			case BPF_JMP | BPF_JEQ | BPF_X:
				ctx->seen |= SEEN_XREG;
				PPC_CMPLW(r_A, r_X);
				break;
			case BPF_JMP | BPF_JSET | BPF_X:
				ctx->seen |= SEEN_XREG;
				PPC_AND_DOT(r_scratch1, r_A, r_X);
				break;
			case BPF_JMP | BPF_JEQ | BPF_K:
			case BPF_JMP | BPF_JGT | BPF_K:
			case BPF_JMP | BPF_JGE | BPF_K:
				if (K < 32768)
					PPC_CMPLWI(r_A, K);
				else {
					PPC_LI32(r_scratch1, K);
					PPC_CMPLW(r_A, r_scratch1);
				}
				break;
			case BPF_JMP | BPF_JSET | BPF_K:
				if (K < 32768)
					/* PPC_ANDI is /only/ dot-form */
					PPC_ANDI(r_scratch1, r_A, K);
				else {
					PPC_LI32(r_scratch1, K);
					PPC_AND_DOT(r_scratch1, r_A,
						    r_scratch1);
				}
				break;
			}
			/* Sometimes branches are constructed "backward", with
			 * the false path being the branch and true path being
			 * a fallthrough to the next instruction.
			 */
			if (filter[i].jt == 0)
				/* Swap the sense of the branch */
				PPC_BCC(true_cond ^ COND_CMP_TRUE,
					addrs[i + 1 + filter[i].jf]);
			else {
				PPC_BCC(true_cond, addrs[i + 1 + filter[i].jt]);
				if (filter[i].jf != 0)
					PPC_JMP(addrs[i + 1 + filter[i].jf]);
			}
			break;
		default:
			/* The filter contains something cruel & unusual.
			 * We don't handle it, but also there shouldn't be
			 * anything missing from our list.
			 */
			if (printk_ratelimit())
				pr_err("BPF filter opcode %04x (@%d) unsupported\n",
				       filter[i].code, i);
			return -ENOTSUPP;
		}

	}
	/* Set end-of-body-code address for exit. */
	addrs[i] = ctx->idx * 4;

	return 0;
}
Exemplo n.º 2
0
/* Assemble the body code between the prologue & epilogue */
static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
			      struct codegen_context *ctx,
			      u32 *addrs, bool extra_pass)
{
	const struct bpf_insn *insn = fp->insnsi;
	int flen = fp->len;
	int i, ret;

	/* Start of epilogue code - will only be valid 2nd pass onwards */
	u32 exit_addr = addrs[flen];

	for (i = 0; i < flen; i++) {
		u32 code = insn[i].code;
		u32 dst_reg = b2p[insn[i].dst_reg];
		u32 src_reg = b2p[insn[i].src_reg];
		s16 off = insn[i].off;
		s32 imm = insn[i].imm;
		bool func_addr_fixed;
		u64 func_addr;
		u64 imm64;
		u32 true_cond;
		u32 tmp_idx;

		/*
		 * addrs[] maps a BPF bytecode address into a real offset from
		 * the start of the body code.
		 */
		addrs[i] = ctx->idx * 4;

		/*
		 * As an optimization, we note down which non-volatile registers
		 * are used so that we can only save/restore those in our
		 * prologue and epilogue. We do this here regardless of whether
		 * the actual BPF instruction uses src/dst registers or not
		 * (for instance, BPF_CALL does not use them). The expectation
		 * is that those instructions will have src_reg/dst_reg set to
		 * 0. Even otherwise, we just lose some prologue/epilogue
		 * optimization but everything else should work without
		 * any issues.
		 */
		if (dst_reg >= BPF_PPC_NVR_MIN && dst_reg < 32)
			bpf_set_seen_register(ctx, insn[i].dst_reg);
		if (src_reg >= BPF_PPC_NVR_MIN && src_reg < 32)
			bpf_set_seen_register(ctx, insn[i].src_reg);

		switch (code) {
		/*
		 * Arithmetic operations: ADD/SUB/MUL/DIV/MOD/NEG
		 */
		case BPF_ALU | BPF_ADD | BPF_X: /* (u32) dst += (u32) src */
		case BPF_ALU64 | BPF_ADD | BPF_X: /* dst += src */
			PPC_ADD(dst_reg, dst_reg, src_reg);
			goto bpf_alu32_trunc;
		case BPF_ALU | BPF_SUB | BPF_X: /* (u32) dst -= (u32) src */
		case BPF_ALU64 | BPF_SUB | BPF_X: /* dst -= src */
			PPC_SUB(dst_reg, dst_reg, src_reg);
			goto bpf_alu32_trunc;
		case BPF_ALU | BPF_ADD | BPF_K: /* (u32) dst += (u32) imm */
		case BPF_ALU | BPF_SUB | BPF_K: /* (u32) dst -= (u32) imm */
		case BPF_ALU64 | BPF_ADD | BPF_K: /* dst += imm */
		case BPF_ALU64 | BPF_SUB | BPF_K: /* dst -= imm */
			if (BPF_OP(code) == BPF_SUB)
				imm = -imm;
			if (imm) {
				if (imm >= -32768 && imm < 32768)
					PPC_ADDI(dst_reg, dst_reg, IMM_L(imm));
				else {
					PPC_LI32(b2p[TMP_REG_1], imm);
					PPC_ADD(dst_reg, dst_reg, b2p[TMP_REG_1]);
				}
			}
			goto bpf_alu32_trunc;
		case BPF_ALU | BPF_MUL | BPF_X: /* (u32) dst *= (u32) src */
		case BPF_ALU64 | BPF_MUL | BPF_X: /* dst *= src */
			if (BPF_CLASS(code) == BPF_ALU)
				PPC_MULW(dst_reg, dst_reg, src_reg);
			else
				PPC_MULD(dst_reg, dst_reg, src_reg);
			goto bpf_alu32_trunc;
		case BPF_ALU | BPF_MUL | BPF_K: /* (u32) dst *= (u32) imm */
		case BPF_ALU64 | BPF_MUL | BPF_K: /* dst *= imm */
			if (imm >= -32768 && imm < 32768)
				PPC_MULI(dst_reg, dst_reg, IMM_L(imm));
			else {
				PPC_LI32(b2p[TMP_REG_1], imm);
				if (BPF_CLASS(code) == BPF_ALU)
					PPC_MULW(dst_reg, dst_reg,
							b2p[TMP_REG_1]);
				else
					PPC_MULD(dst_reg, dst_reg,
							b2p[TMP_REG_1]);
			}
			goto bpf_alu32_trunc;
		case BPF_ALU | BPF_DIV | BPF_X: /* (u32) dst /= (u32) src */
		case BPF_ALU | BPF_MOD | BPF_X: /* (u32) dst %= (u32) src */
			if (BPF_OP(code) == BPF_MOD) {
				PPC_DIVWU(b2p[TMP_REG_1], dst_reg, src_reg);
				PPC_MULW(b2p[TMP_REG_1], src_reg,
						b2p[TMP_REG_1]);
				PPC_SUB(dst_reg, dst_reg, b2p[TMP_REG_1]);
			} else
				PPC_DIVWU(dst_reg, dst_reg, src_reg);
			goto bpf_alu32_trunc;
		case BPF_ALU64 | BPF_DIV | BPF_X: /* dst /= src */
		case BPF_ALU64 | BPF_MOD | BPF_X: /* dst %= src */
			if (BPF_OP(code) == BPF_MOD) {
				PPC_DIVD(b2p[TMP_REG_1], dst_reg, src_reg);
				PPC_MULD(b2p[TMP_REG_1], src_reg,
						b2p[TMP_REG_1]);
				PPC_SUB(dst_reg, dst_reg, b2p[TMP_REG_1]);
			} else
				PPC_DIVD(dst_reg, dst_reg, src_reg);
			break;
		case BPF_ALU | BPF_MOD | BPF_K: /* (u32) dst %= (u32) imm */
		case BPF_ALU | BPF_DIV | BPF_K: /* (u32) dst /= (u32) imm */
		case BPF_ALU64 | BPF_MOD | BPF_K: /* dst %= imm */
		case BPF_ALU64 | BPF_DIV | BPF_K: /* dst /= imm */
			if (imm == 0)
				return -EINVAL;
			else if (imm == 1)
				goto bpf_alu32_trunc;

			PPC_LI32(b2p[TMP_REG_1], imm);
			switch (BPF_CLASS(code)) {
			case BPF_ALU:
				if (BPF_OP(code) == BPF_MOD) {
					PPC_DIVWU(b2p[TMP_REG_2], dst_reg,
							b2p[TMP_REG_1]);
					PPC_MULW(b2p[TMP_REG_1],
							b2p[TMP_REG_1],
							b2p[TMP_REG_2]);
					PPC_SUB(dst_reg, dst_reg,
							b2p[TMP_REG_1]);
				} else
					PPC_DIVWU(dst_reg, dst_reg,
							b2p[TMP_REG_1]);
				break;
			case BPF_ALU64:
				if (BPF_OP(code) == BPF_MOD) {
					PPC_DIVD(b2p[TMP_REG_2], dst_reg,
							b2p[TMP_REG_1]);
					PPC_MULD(b2p[TMP_REG_1],
							b2p[TMP_REG_1],
							b2p[TMP_REG_2]);
					PPC_SUB(dst_reg, dst_reg,
							b2p[TMP_REG_1]);
				} else
					PPC_DIVD(dst_reg, dst_reg,
							b2p[TMP_REG_1]);
				break;
			}
			goto bpf_alu32_trunc;
		case BPF_ALU | BPF_NEG: /* (u32) dst = -dst */
		case BPF_ALU64 | BPF_NEG: /* dst = -dst */
			PPC_NEG(dst_reg, dst_reg);
			goto bpf_alu32_trunc;

		/*
		 * Logical operations: AND/OR/XOR/[A]LSH/[A]RSH
		 */
		case BPF_ALU | BPF_AND | BPF_X: /* (u32) dst = dst & src */
		case BPF_ALU64 | BPF_AND | BPF_X: /* dst = dst & src */
			PPC_AND(dst_reg, dst_reg, src_reg);
			goto bpf_alu32_trunc;
		case BPF_ALU | BPF_AND | BPF_K: /* (u32) dst = dst & imm */
		case BPF_ALU64 | BPF_AND | BPF_K: /* dst = dst & imm */
			if (!IMM_H(imm))
				PPC_ANDI(dst_reg, dst_reg, IMM_L(imm));
			else {
				/* Sign-extended */
				PPC_LI32(b2p[TMP_REG_1], imm);
				PPC_AND(dst_reg, dst_reg, b2p[TMP_REG_1]);
			}
			goto bpf_alu32_trunc;
		case BPF_ALU | BPF_OR | BPF_X: /* dst = (u32) dst | (u32) src */
		case BPF_ALU64 | BPF_OR | BPF_X: /* dst = dst | src */
			PPC_OR(dst_reg, dst_reg, src_reg);
			goto bpf_alu32_trunc;
		case BPF_ALU | BPF_OR | BPF_K:/* dst = (u32) dst | (u32) imm */
		case BPF_ALU64 | BPF_OR | BPF_K:/* dst = dst | imm */
			if (imm < 0 && BPF_CLASS(code) == BPF_ALU64) {
				/* Sign-extended */
				PPC_LI32(b2p[TMP_REG_1], imm);
				PPC_OR(dst_reg, dst_reg, b2p[TMP_REG_1]);
			} else {
				if (IMM_L(imm))
					PPC_ORI(dst_reg, dst_reg, IMM_L(imm));
				if (IMM_H(imm))
					PPC_ORIS(dst_reg, dst_reg, IMM_H(imm));
			}
			goto bpf_alu32_trunc;
		case BPF_ALU | BPF_XOR | BPF_X: /* (u32) dst ^= src */
		case BPF_ALU64 | BPF_XOR | BPF_X: /* dst ^= src */
			PPC_XOR(dst_reg, dst_reg, src_reg);
			goto bpf_alu32_trunc;
		case BPF_ALU | BPF_XOR | BPF_K: /* (u32) dst ^= (u32) imm */
		case BPF_ALU64 | BPF_XOR | BPF_K: /* dst ^= imm */
			if (imm < 0 && BPF_CLASS(code) == BPF_ALU64) {
				/* Sign-extended */
				PPC_LI32(b2p[TMP_REG_1], imm);
				PPC_XOR(dst_reg, dst_reg, b2p[TMP_REG_1]);
			} else {
				if (IMM_L(imm))
					PPC_XORI(dst_reg, dst_reg, IMM_L(imm));
				if (IMM_H(imm))
					PPC_XORIS(dst_reg, dst_reg, IMM_H(imm));
			}
			goto bpf_alu32_trunc;
		case BPF_ALU | BPF_LSH | BPF_X: /* (u32) dst <<= (u32) src */
			/* slw clears top 32 bits */
			PPC_SLW(dst_reg, dst_reg, src_reg);
			break;
		case BPF_ALU64 | BPF_LSH | BPF_X: /* dst <<= src; */
			PPC_SLD(dst_reg, dst_reg, src_reg);
			break;
		case BPF_ALU | BPF_LSH | BPF_K: /* (u32) dst <<== (u32) imm */
			/* with imm 0, we still need to clear top 32 bits */
			PPC_SLWI(dst_reg, dst_reg, imm);
			break;
		case BPF_ALU64 | BPF_LSH | BPF_K: /* dst <<== imm */
			if (imm != 0)
				PPC_SLDI(dst_reg, dst_reg, imm);
			break;
		case BPF_ALU | BPF_RSH | BPF_X: /* (u32) dst >>= (u32) src */
			PPC_SRW(dst_reg, dst_reg, src_reg);
			break;
		case BPF_ALU64 | BPF_RSH | BPF_X: /* dst >>= src */
			PPC_SRD(dst_reg, dst_reg, src_reg);
			break;
		case BPF_ALU | BPF_RSH | BPF_K: /* (u32) dst >>= (u32) imm */
			PPC_SRWI(dst_reg, dst_reg, imm);
			break;
		case BPF_ALU64 | BPF_RSH | BPF_K: /* dst >>= imm */
			if (imm != 0)
				PPC_SRDI(dst_reg, dst_reg, imm);
			break;
		case BPF_ALU | BPF_ARSH | BPF_X: /* (s32) dst >>= src */
			PPC_SRAW(dst_reg, dst_reg, src_reg);
			goto bpf_alu32_trunc;
		case BPF_ALU64 | BPF_ARSH | BPF_X: /* (s64) dst >>= src */
			PPC_SRAD(dst_reg, dst_reg, src_reg);
			break;
		case BPF_ALU | BPF_ARSH | BPF_K: /* (s32) dst >>= imm */
			PPC_SRAWI(dst_reg, dst_reg, imm);
			goto bpf_alu32_trunc;
		case BPF_ALU64 | BPF_ARSH | BPF_K: /* (s64) dst >>= imm */
			if (imm != 0)
				PPC_SRADI(dst_reg, dst_reg, imm);
			break;

		/*
		 * MOV
		 */
		case BPF_ALU | BPF_MOV | BPF_X: /* (u32) dst = src */
		case BPF_ALU64 | BPF_MOV | BPF_X: /* dst = src */
			PPC_MR(dst_reg, src_reg);
			goto bpf_alu32_trunc;
		case BPF_ALU | BPF_MOV | BPF_K: /* (u32) dst = imm */
		case BPF_ALU64 | BPF_MOV | BPF_K: /* dst = (s64) imm */
			PPC_LI32(dst_reg, imm);
			if (imm < 0)
				goto bpf_alu32_trunc;
			break;

bpf_alu32_trunc:
		/* Truncate to 32-bits */
		if (BPF_CLASS(code) == BPF_ALU)
			PPC_RLWINM(dst_reg, dst_reg, 0, 0, 31);
		break;

		/*
		 * BPF_FROM_BE/LE
		 */
		case BPF_ALU | BPF_END | BPF_FROM_LE:
		case BPF_ALU | BPF_END | BPF_FROM_BE:
#ifdef __BIG_ENDIAN__
			if (BPF_SRC(code) == BPF_FROM_BE)
				goto emit_clear;
#else /* !__BIG_ENDIAN__ */
			if (BPF_SRC(code) == BPF_FROM_LE)
				goto emit_clear;
#endif
			switch (imm) {
			case 16:
				/* Rotate 8 bits left & mask with 0x0000ff00 */
				PPC_RLWINM(b2p[TMP_REG_1], dst_reg, 8, 16, 23);
				/* Rotate 8 bits right & insert LSB to reg */
				PPC_RLWIMI(b2p[TMP_REG_1], dst_reg, 24, 24, 31);
				/* Move result back to dst_reg */
				PPC_MR(dst_reg, b2p[TMP_REG_1]);
				break;
			case 32:
				/*
				 * Rotate word left by 8 bits:
				 * 2 bytes are already in their final position
				 * -- byte 2 and 4 (of bytes 1, 2, 3 and 4)
				 */
				PPC_RLWINM(b2p[TMP_REG_1], dst_reg, 8, 0, 31);
				/* Rotate 24 bits and insert byte 1 */
				PPC_RLWIMI(b2p[TMP_REG_1], dst_reg, 24, 0, 7);
				/* Rotate 24 bits and insert byte 3 */
				PPC_RLWIMI(b2p[TMP_REG_1], dst_reg, 24, 16, 23);
				PPC_MR(dst_reg, b2p[TMP_REG_1]);
				break;
			case 64:
				/*
				 * Way easier and faster(?) to store the value
				 * into stack and then use ldbrx
				 *
				 * ctx->seen will be reliable in pass2, but
				 * the instructions generated will remain the
				 * same across all passes
				 */
				PPC_STD(dst_reg, 1, bpf_jit_stack_local(ctx));
				PPC_ADDI(b2p[TMP_REG_1], 1, bpf_jit_stack_local(ctx));
				PPC_LDBRX(dst_reg, 0, b2p[TMP_REG_1]);
				break;
			}
			break;

emit_clear:
			switch (imm) {
			case 16:
				/* zero-extend 16 bits into 64 bits */
				PPC_RLDICL(dst_reg, dst_reg, 0, 48);
				break;
			case 32:
				/* zero-extend 32 bits into 64 bits */
				PPC_RLDICL(dst_reg, dst_reg, 0, 32);
				break;
			case 64:
				/* nop */
				break;
			}
			break;

		/*
		 * BPF_ST(X)
		 */
		case BPF_STX | BPF_MEM | BPF_B: /* *(u8 *)(dst + off) = src */
		case BPF_ST | BPF_MEM | BPF_B: /* *(u8 *)(dst + off) = imm */
			if (BPF_CLASS(code) == BPF_ST) {
				PPC_LI(b2p[TMP_REG_1], imm);
				src_reg = b2p[TMP_REG_1];
			}
			PPC_STB(src_reg, dst_reg, off);
			break;
		case BPF_STX | BPF_MEM | BPF_H: /* (u16 *)(dst + off) = src */
		case BPF_ST | BPF_MEM | BPF_H: /* (u16 *)(dst + off) = imm */
			if (BPF_CLASS(code) == BPF_ST) {
				PPC_LI(b2p[TMP_REG_1], imm);
				src_reg = b2p[TMP_REG_1];
			}
			PPC_STH(src_reg, dst_reg, off);
			break;
		case BPF_STX | BPF_MEM | BPF_W: /* *(u32 *)(dst + off) = src */
		case BPF_ST | BPF_MEM | BPF_W: /* *(u32 *)(dst + off) = imm */
			if (BPF_CLASS(code) == BPF_ST) {
				PPC_LI32(b2p[TMP_REG_1], imm);
				src_reg = b2p[TMP_REG_1];
			}
			PPC_STW(src_reg, dst_reg, off);
			break;
		case BPF_STX | BPF_MEM | BPF_DW: /* (u64 *)(dst + off) = src */
		case BPF_ST | BPF_MEM | BPF_DW: /* *(u64 *)(dst + off) = imm */
			if (BPF_CLASS(code) == BPF_ST) {
				PPC_LI32(b2p[TMP_REG_1], imm);
				src_reg = b2p[TMP_REG_1];
			}
			PPC_STD(src_reg, dst_reg, off);
			break;

		/*
		 * BPF_STX XADD (atomic_add)
		 */
		/* *(u32 *)(dst + off) += src */
		case BPF_STX | BPF_XADD | BPF_W:
			/* Get EA into TMP_REG_1 */
			PPC_ADDI(b2p[TMP_REG_1], dst_reg, off);
			tmp_idx = ctx->idx * 4;
			/* load value from memory into TMP_REG_2 */
			PPC_BPF_LWARX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1], 0);
			/* add value from src_reg into this */
			PPC_ADD(b2p[TMP_REG_2], b2p[TMP_REG_2], src_reg);
			/* store result back */
			PPC_BPF_STWCX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1]);
			/* we're done if this succeeded */
			PPC_BCC_SHORT(COND_NE, tmp_idx);
			break;
		/* *(u64 *)(dst + off) += src */
		case BPF_STX | BPF_XADD | BPF_DW:
			PPC_ADDI(b2p[TMP_REG_1], dst_reg, off);
			tmp_idx = ctx->idx * 4;
			PPC_BPF_LDARX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1], 0);
			PPC_ADD(b2p[TMP_REG_2], b2p[TMP_REG_2], src_reg);
			PPC_BPF_STDCX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1]);
			PPC_BCC_SHORT(COND_NE, tmp_idx);
			break;

		/*
		 * BPF_LDX
		 */
		/* dst = *(u8 *)(ul) (src + off) */
		case BPF_LDX | BPF_MEM | BPF_B:
			PPC_LBZ(dst_reg, src_reg, off);
			break;
		/* dst = *(u16 *)(ul) (src + off) */
		case BPF_LDX | BPF_MEM | BPF_H:
			PPC_LHZ(dst_reg, src_reg, off);
			break;
		/* dst = *(u32 *)(ul) (src + off) */
		case BPF_LDX | BPF_MEM | BPF_W:
			PPC_LWZ(dst_reg, src_reg, off);
			break;
		/* dst = *(u64 *)(ul) (src + off) */
		case BPF_LDX | BPF_MEM | BPF_DW:
			PPC_LD(dst_reg, src_reg, off);
			break;

		/*
		 * Doubleword load
		 * 16 byte instruction that uses two 'struct bpf_insn'
		 */
		case BPF_LD | BPF_IMM | BPF_DW: /* dst = (u64) imm */
			imm64 = ((u64)(u32) insn[i].imm) |
				    (((u64)(u32) insn[i+1].imm) << 32);
			/* Adjust for two bpf instructions */
			addrs[++i] = ctx->idx * 4;
			PPC_LI64(dst_reg, imm64);
			break;

		/*
		 * Return/Exit
		 */
		case BPF_JMP | BPF_EXIT:
			/*
			 * If this isn't the very last instruction, branch to
			 * the epilogue. If we _are_ the last instruction,
			 * we'll just fall through to the epilogue.
			 */
			if (i != flen - 1)
				PPC_JMP(exit_addr);
			/* else fall through to the epilogue */
			break;

		/*
		 * Call kernel helper or bpf function
		 */
		case BPF_JMP | BPF_CALL:
			ctx->seen |= SEEN_FUNC;

			ret = bpf_jit_get_func_addr(fp, &insn[i], extra_pass,
						    &func_addr, &func_addr_fixed);
			if (ret < 0)
				return ret;

			if (func_addr_fixed)
				bpf_jit_emit_func_call_hlp(image, ctx, func_addr);
			else
				bpf_jit_emit_func_call_rel(image, ctx, func_addr);
			/* move return value from r3 to BPF_REG_0 */
			PPC_MR(b2p[BPF_REG_0], 3);
			break;

		/*
		 * Jumps and branches
		 */
		case BPF_JMP | BPF_JA:
			PPC_JMP(addrs[i + 1 + off]);
			break;

		case BPF_JMP | BPF_JGT | BPF_K:
		case BPF_JMP | BPF_JGT | BPF_X:
		case BPF_JMP | BPF_JSGT | BPF_K:
		case BPF_JMP | BPF_JSGT | BPF_X:
			true_cond = COND_GT;
			goto cond_branch;
		case BPF_JMP | BPF_JLT | BPF_K:
		case BPF_JMP | BPF_JLT | BPF_X:
		case BPF_JMP | BPF_JSLT | BPF_K:
		case BPF_JMP | BPF_JSLT | BPF_X:
			true_cond = COND_LT;
			goto cond_branch;
		case BPF_JMP | BPF_JGE | BPF_K:
		case BPF_JMP | BPF_JGE | BPF_X:
		case BPF_JMP | BPF_JSGE | BPF_K:
		case BPF_JMP | BPF_JSGE | BPF_X:
			true_cond = COND_GE;
			goto cond_branch;
		case BPF_JMP | BPF_JLE | BPF_K:
		case BPF_JMP | BPF_JLE | BPF_X:
		case BPF_JMP | BPF_JSLE | BPF_K:
		case BPF_JMP | BPF_JSLE | BPF_X:
			true_cond = COND_LE;
			goto cond_branch;
		case BPF_JMP | BPF_JEQ | BPF_K:
		case BPF_JMP | BPF_JEQ | BPF_X:
			true_cond = COND_EQ;
			goto cond_branch;
		case BPF_JMP | BPF_JNE | BPF_K:
		case BPF_JMP | BPF_JNE | BPF_X:
			true_cond = COND_NE;
			goto cond_branch;
		case BPF_JMP | BPF_JSET | BPF_K:
		case BPF_JMP | BPF_JSET | BPF_X:
			true_cond = COND_NE;
			/* Fall through */

cond_branch:
			switch (code) {
			case BPF_JMP | BPF_JGT | BPF_X:
			case BPF_JMP | BPF_JLT | BPF_X:
			case BPF_JMP | BPF_JGE | BPF_X:
			case BPF_JMP | BPF_JLE | BPF_X:
			case BPF_JMP | BPF_JEQ | BPF_X:
			case BPF_JMP | BPF_JNE | BPF_X:
				/* unsigned comparison */
				PPC_CMPLD(dst_reg, src_reg);
				break;
			case BPF_JMP | BPF_JSGT | BPF_X:
			case BPF_JMP | BPF_JSLT | BPF_X:
			case BPF_JMP | BPF_JSGE | BPF_X:
			case BPF_JMP | BPF_JSLE | BPF_X:
				/* signed comparison */
				PPC_CMPD(dst_reg, src_reg);
				break;
			case BPF_JMP | BPF_JSET | BPF_X:
				PPC_AND_DOT(b2p[TMP_REG_1], dst_reg, src_reg);
				break;
			case BPF_JMP | BPF_JNE | BPF_K:
			case BPF_JMP | BPF_JEQ | BPF_K:
			case BPF_JMP | BPF_JGT | BPF_K:
			case BPF_JMP | BPF_JLT | BPF_K:
			case BPF_JMP | BPF_JGE | BPF_K:
			case BPF_JMP | BPF_JLE | BPF_K:
				/*
				 * Need sign-extended load, so only positive
				 * values can be used as imm in cmpldi
				 */
				if (imm >= 0 && imm < 32768)
					PPC_CMPLDI(dst_reg, imm);
				else {
					/* sign-extending load */
					PPC_LI32(b2p[TMP_REG_1], imm);
					/* ... but unsigned comparison */
					PPC_CMPLD(dst_reg, b2p[TMP_REG_1]);
				}
				break;
			case BPF_JMP | BPF_JSGT | BPF_K:
			case BPF_JMP | BPF_JSLT | BPF_K:
			case BPF_JMP | BPF_JSGE | BPF_K:
			case BPF_JMP | BPF_JSLE | BPF_K:
				/*
				 * signed comparison, so any 16-bit value
				 * can be used in cmpdi
				 */
				if (imm >= -32768 && imm < 32768)
					PPC_CMPDI(dst_reg, imm);
				else {
					PPC_LI32(b2p[TMP_REG_1], imm);
					PPC_CMPD(dst_reg, b2p[TMP_REG_1]);
				}
				break;
			case BPF_JMP | BPF_JSET | BPF_K:
				/* andi does not sign-extend the immediate */
				if (imm >= 0 && imm < 32768)
					/* PPC_ANDI is _only/always_ dot-form */
					PPC_ANDI(b2p[TMP_REG_1], dst_reg, imm);
				else {
					PPC_LI32(b2p[TMP_REG_1], imm);
					PPC_AND_DOT(b2p[TMP_REG_1], dst_reg,
						    b2p[TMP_REG_1]);
				}
				break;
			}
			PPC_BCC(true_cond, addrs[i + 1 + off]);
			break;

		/*
		 * Tail call
		 */
		case BPF_JMP | BPF_TAIL_CALL:
			ctx->seen |= SEEN_TAILCALL;
			bpf_jit_emit_tail_call(image, ctx, addrs[i + 1]);
			break;

		default:
			/*
			 * The filter contains something cruel & unusual.
			 * We don't handle it, but also there shouldn't be
			 * anything missing from our list.
			 */
			pr_err_ratelimited("eBPF filter opcode %04x (@%d) unsupported\n",
					code, i);
			return -ENOTSUPP;
		}
	}

	/* Set end-of-body-code address for exit. */
	addrs[i] = ctx->idx * 4;

	return 0;
}
Exemplo n.º 3
0
/* Assemble the body code between the prologue & epilogue. */
static int bpf_jit_build_body(struct sk_filter *fp, u32 *image,
			      struct codegen_context *ctx,
			      unsigned int *addrs)
{
	const struct sock_filter *filter = fp->insns;
	int flen = fp->len;
	u8 *func;
	unsigned int true_cond;
	int i;

	/* Start of epilogue code */
	unsigned int exit_addr = addrs[flen];

	for (i = 0; i < flen; i++) {
		unsigned int K = filter[i].k;

		/*
		 * addrs[] maps a BPF bytecode address into a real offset from
		 * the start of the body code.
		 */
		addrs[i] = ctx->idx * 4;

		switch (filter[i].code) {
			/*** ALU ops ***/
		case BPF_S_ALU_ADD_X: /* A += X; */
			ctx->seen |= SEEN_XREG;
			PPC_ADD(r_A, r_A, r_X);
			break;
		case BPF_S_ALU_ADD_K: /* A += K; */
			if (!K)
				break;
			PPC_ADDI(r_A, r_A, IMM_L(K));
			if (K >= 32768)
				PPC_ADDIS(r_A, r_A, IMM_HA(K));
			break;
		case BPF_S_ALU_SUB_X: /* A -= X; */
			ctx->seen |= SEEN_XREG;
			PPC_SUB(r_A, r_A, r_X);
			break;
		case BPF_S_ALU_SUB_K: /* A -= K */
			if (!K)
				break;
			PPC_ADDI(r_A, r_A, IMM_L(-K));
			if (K >= 32768)
				PPC_ADDIS(r_A, r_A, IMM_HA(-K));
			break;
		case BPF_S_ALU_MUL_X: /* A *= X; */
			ctx->seen |= SEEN_XREG;
			PPC_MUL(r_A, r_A, r_X);
			break;
		case BPF_S_ALU_MUL_K: /* A *= K */
			if (K < 32768)
				PPC_MULI(r_A, r_A, K);
			else {
				PPC_LI32(r_scratch1, K);
				PPC_MUL(r_A, r_A, r_scratch1);
			}
			break;
		case BPF_S_ALU_DIV_X: /* A /= X; */
			ctx->seen |= SEEN_XREG;
			PPC_CMPWI(r_X, 0);
			if (ctx->pc_ret0 != -1) {
				PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]);
			} else {
				/*
				 * Exit, returning 0; first pass hits here
				 * (longer worst-case code size).
				 */
				PPC_BCC_SHORT(COND_NE, (ctx->idx*4)+12);
				PPC_LI(r_ret, 0);
				PPC_JMP(exit_addr);
			}
			PPC_DIVWU(r_A, r_A, r_X);
			break;
		case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K); */
			PPC_LI32(r_scratch1, K);
			/* Top 32 bits of 64bit result -> A */
			PPC_MULHWU(r_A, r_A, r_scratch1);
			break;
		case BPF_S_ALU_AND_X:
			ctx->seen |= SEEN_XREG;
			PPC_AND(r_A, r_A, r_X);
			break;
		case BPF_S_ALU_AND_K:
			if (!IMM_H(K))
				PPC_ANDI(r_A, r_A, K);
			else {
				PPC_LI32(r_scratch1, K);
				PPC_AND(r_A, r_A, r_scratch1);
			}
			break;
		case BPF_S_ALU_OR_X:
			ctx->seen |= SEEN_XREG;
			PPC_OR(r_A, r_A, r_X);
			break;
		case BPF_S_ALU_OR_K:
			if (IMM_L(K))
				PPC_ORI(r_A, r_A, IMM_L(K));
			if (K >= 65536)
				PPC_ORIS(r_A, r_A, IMM_H(K));
			break;
		case BPF_S_ALU_LSH_X: /* A <<= X; */
			ctx->seen |= SEEN_XREG;
			PPC_SLW(r_A, r_A, r_X);
			break;
		case BPF_S_ALU_LSH_K:
			if (K == 0)
				break;
			else
				PPC_SLWI(r_A, r_A, K);
			break;
		case BPF_S_ALU_RSH_X: /* A >>= X; */
			ctx->seen |= SEEN_XREG;
			PPC_SRW(r_A, r_A, r_X);
			break;
		case BPF_S_ALU_RSH_K: /* A >>= K; */
			if (K == 0)
				break;
			else
				PPC_SRWI(r_A, r_A, K);
			break;
		case BPF_S_ALU_NEG:
			PPC_NEG(r_A, r_A);
			break;
		case BPF_S_RET_K:
			PPC_LI32(r_ret, K);
			if (!K) {
				if (ctx->pc_ret0 == -1)
					ctx->pc_ret0 = i;
			}
			/*
			 * If this isn't the very last instruction, branch to
			 * the epilogue if we've stuff to clean up.  Otherwise,
			 * if there's nothing to tidy, just return.  If we /are/
			 * the last instruction, we're about to fall through to
			 * the epilogue to return.
			 */
			if (i != flen - 1) {
				/*
				 * Note: 'seen' is properly valid only on pass
				 * #2.	Both parts of this conditional are the
				 * same instruction size though, meaning the
				 * first pass will still correctly determine the
				 * code size/addresses.
				 */
				if (ctx->seen)
					PPC_JMP(exit_addr);
				else
					PPC_BLR();
			}
			break;
		case BPF_S_RET_A:
			PPC_MR(r_ret, r_A);
			if (i != flen - 1) {
				if (ctx->seen)
					PPC_JMP(exit_addr);
				else
					PPC_BLR();
			}
			break;
		case BPF_S_MISC_TAX: /* X = A */
			PPC_MR(r_X, r_A);
			break;
		case BPF_S_MISC_TXA: /* A = X */
			ctx->seen |= SEEN_XREG;
			PPC_MR(r_A, r_X);
			break;

			/*** Constant loads/M[] access ***/
		case BPF_S_LD_IMM: /* A = K */
			PPC_LI32(r_A, K);
			break;
		case BPF_S_LDX_IMM: /* X = K */
			PPC_LI32(r_X, K);
			break;
		case BPF_S_LD_MEM: /* A = mem[K] */
			PPC_MR(r_A, r_M + (K & 0xf));
			ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
			break;
		case BPF_S_LDX_MEM: /* X = mem[K] */
			PPC_MR(r_X, r_M + (K & 0xf));
			ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
			break;
		case BPF_S_ST: /* mem[K] = A */
			PPC_MR(r_M + (K & 0xf), r_A);
			ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
			break;
		case BPF_S_STX: /* mem[K] = X */
			PPC_MR(r_M + (K & 0xf), r_X);
			ctx->seen |= SEEN_XREG | SEEN_MEM | (1<<(K & 0xf));
			break;
		case BPF_S_LD_W_LEN: /*	A = skb->len; */
			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
			PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff, len));
			break;
		case BPF_S_LDX_W_LEN: /* X = skb->len; */
			PPC_LWZ_OFFS(r_X, r_skb, offsetof(struct sk_buff, len));
			break;

			/*** Ancillary info loads ***/

			/* None of the BPF_S_ANC* codes appear to be passed by
			 * sk_chk_filter().  The interpreter and the x86 BPF
			 * compiler implement them so we do too -- they may be
			 * planted in future.
			 */
		case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
						  protocol) != 2);
			PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
							  protocol));
			/* ntohs is a NOP with BE loads. */
			break;
		case BPF_S_ANC_IFINDEX:
			PPC_LD_OFFS(r_scratch1, r_skb, offsetof(struct sk_buff,
								dev));
			PPC_CMPDI(r_scratch1, 0);
			if (ctx->pc_ret0 != -1) {
				PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]);
			} else {
				/* Exit, returning 0; first pass hits here. */
				PPC_BCC_SHORT(COND_NE, (ctx->idx*4)+12);
				PPC_LI(r_ret, 0);
				PPC_JMP(exit_addr);
			}
			BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
						  ifindex) != 4);
			PPC_LWZ_OFFS(r_A, r_scratch1,
				     offsetof(struct net_device, ifindex));
			break;
		case BPF_S_ANC_MARK:
			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
			PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
							  mark));
			break;
		case BPF_S_ANC_RXHASH:
			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
			PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
							  rxhash));
			break;
		case BPF_S_ANC_QUEUE:
			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
						  queue_mapping) != 2);
			PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
							  queue_mapping));
			break;
		case BPF_S_ANC_CPU:
#ifdef CONFIG_SMP
			/*
			 * PACA ptr is r13:
			 * raw_smp_processor_id() = local_paca->paca_index
			 */
			BUILD_BUG_ON(FIELD_SIZEOF(struct paca_struct,
						  paca_index) != 2);
			PPC_LHZ_OFFS(r_A, 13,
				     offsetof(struct paca_struct, paca_index));
#else
			PPC_LI(r_A, 0);
#endif
			break;

			/*** Absolute loads from packet header/data ***/
		case BPF_S_LD_W_ABS:
			func = sk_load_word;
			goto common_load;
		case BPF_S_LD_H_ABS:
			func = sk_load_half;
			goto common_load;
		case BPF_S_LD_B_ABS:
			func = sk_load_byte;
		common_load:
			/*
			 * Load from [K].  Reference with the (negative)
			 * SKF_NET_OFF/SKF_LL_OFF offsets is unsupported.
			 */
			ctx->seen |= SEEN_DATAREF;
			if ((int)K < 0)
				return -ENOTSUPP;
			PPC_LI64(r_scratch1, func);
			PPC_MTLR(r_scratch1);
			PPC_LI32(r_addr, K);
			PPC_BLRL();
			/*
			 * Helper returns 'lt' condition on error, and an
			 * appropriate return value in r3
			 */
			PPC_BCC(COND_LT, exit_addr);
			break;

			/*** Indirect loads from packet header/data ***/
		case BPF_S_LD_W_IND:
			func = sk_load_word;
			goto common_load_ind;
		case BPF_S_LD_H_IND:
			func = sk_load_half;
			goto common_load_ind;
		case BPF_S_LD_B_IND:
			func = sk_load_byte;
		common_load_ind:
			/*
			 * Load from [X + K].  Negative offsets are tested for
			 * in the helper functions, and result in a 'ret 0'.
			 */
			ctx->seen |= SEEN_DATAREF | SEEN_XREG;
			PPC_LI64(r_scratch1, func);
			PPC_MTLR(r_scratch1);
			PPC_ADDI(r_addr, r_X, IMM_L(K));
			if (K >= 32768)
				PPC_ADDIS(r_addr, r_addr, IMM_HA(K));
			PPC_BLRL();
			/* If error, cr0.LT set */
			PPC_BCC(COND_LT, exit_addr);
			break;

		case BPF_S_LDX_B_MSH:
			/*
			 * x86 version drops packet (RET 0) when K<0, whereas
			 * interpreter does allow K<0 (__load_pointer, special
			 * ancillary data).  common_load returns ENOTSUPP if K<0,
			 * so we fall back to interpreter & filter works.
			 */
			func = sk_load_byte_msh;
			goto common_load;
			break;

			/*** Jump and branches ***/
		case BPF_S_JMP_JA:
			if (K != 0)
				PPC_JMP(addrs[i + 1 + K]);
			break;

		case BPF_S_JMP_JGT_K:
		case BPF_S_JMP_JGT_X:
			true_cond = COND_GT;
			goto cond_branch;
		case BPF_S_JMP_JGE_K:
		case BPF_S_JMP_JGE_X:
			true_cond = COND_GE;
			goto cond_branch;
		case BPF_S_JMP_JEQ_K:
		case BPF_S_JMP_JEQ_X:
			true_cond = COND_EQ;
			goto cond_branch;
		case BPF_S_JMP_JSET_K:
		case BPF_S_JMP_JSET_X:
			true_cond = COND_NE;
			/* Fall through */
		cond_branch:
			/* same targets, can avoid doing the test :) */
			if (filter[i].jt == filter[i].jf) {
				if (filter[i].jt > 0)
					PPC_JMP(addrs[i + 1 + filter[i].jt]);
				break;
			}

			switch (filter[i].code) {
			case BPF_S_JMP_JGT_X:
			case BPF_S_JMP_JGE_X:
			case BPF_S_JMP_JEQ_X:
				ctx->seen |= SEEN_XREG;
				PPC_CMPLW(r_A, r_X);
				break;
			case BPF_S_JMP_JSET_X:
				ctx->seen |= SEEN_XREG;
				PPC_AND_DOT(r_scratch1, r_A, r_X);
				break;
			case BPF_S_JMP_JEQ_K:
			case BPF_S_JMP_JGT_K:
			case BPF_S_JMP_JGE_K:
				if (K < 32768)
					PPC_CMPLWI(r_A, K);
				else {
					PPC_LI32(r_scratch1, K);
					PPC_CMPLW(r_A, r_scratch1);
				}
				break;
			case BPF_S_JMP_JSET_K:
				if (K < 32768)
					/* PPC_ANDI is /only/ dot-form */
					PPC_ANDI(r_scratch1, r_A, K);
				else {
					PPC_LI32(r_scratch1, K);
					PPC_AND_DOT(r_scratch1, r_A,
						    r_scratch1);
				}
				break;
			}
			/* Sometimes branches are constructed "backward", with
			 * the false path being the branch and true path being
			 * a fallthrough to the next instruction.
			 */
			if (filter[i].jt == 0)
				/* Swap the sense of the branch */
				PPC_BCC(true_cond ^ COND_CMP_TRUE,
					addrs[i + 1 + filter[i].jf]);
			else {
				PPC_BCC(true_cond, addrs[i + 1 + filter[i].jt]);
				if (filter[i].jf != 0)
					PPC_JMP(addrs[i + 1 + filter[i].jf]);
			}
			break;
		default:
			/* The filter contains something cruel & unusual.
			 * We don't handle it, but also there shouldn't be
			 * anything missing from our list.
			 */
			if (printk_ratelimit())
				pr_err("BPF filter opcode %04x (@%d) unsupported\n",
				       filter[i].code, i);
			return -ENOTSUPP;
		}

	}
	/* Set end-of-body-code address for exit. */
	addrs[i] = ctx->idx * 4;

	return 0;
}
Exemplo n.º 4
0
static void bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 out)
{
	/*
	 * By now, the eBPF program has already setup parameters in r3, r4 and r5
	 * r3/BPF_REG_1 - pointer to ctx -- passed as is to the next bpf program
	 * r4/BPF_REG_2 - pointer to bpf_array
	 * r5/BPF_REG_3 - index in bpf_array
	 */
	int b2p_bpf_array = b2p[BPF_REG_2];
	int b2p_index = b2p[BPF_REG_3];

	/*
	 * if (index >= array->map.max_entries)
	 *   goto out;
	 */
	PPC_LWZ(b2p[TMP_REG_1], b2p_bpf_array, offsetof(struct bpf_array, map.max_entries));
	PPC_RLWINM(b2p_index, b2p_index, 0, 0, 31);
	PPC_CMPLW(b2p_index, b2p[TMP_REG_1]);
	PPC_BCC(COND_GE, out);

	/*
	 * if (tail_call_cnt > MAX_TAIL_CALL_CNT)
	 *   goto out;
	 */
	PPC_LD(b2p[TMP_REG_1], 1, bpf_jit_stack_tailcallcnt(ctx));
	PPC_CMPLWI(b2p[TMP_REG_1], MAX_TAIL_CALL_CNT);
	PPC_BCC(COND_GT, out);

	/*
	 * tail_call_cnt++;
	 */
	PPC_ADDI(b2p[TMP_REG_1], b2p[TMP_REG_1], 1);
	PPC_BPF_STL(b2p[TMP_REG_1], 1, bpf_jit_stack_tailcallcnt(ctx));

	/* prog = array->ptrs[index]; */
	PPC_MULI(b2p[TMP_REG_1], b2p_index, 8);
	PPC_ADD(b2p[TMP_REG_1], b2p[TMP_REG_1], b2p_bpf_array);
	PPC_LD(b2p[TMP_REG_1], b2p[TMP_REG_1], offsetof(struct bpf_array, ptrs));

	/*
	 * if (prog == NULL)
	 *   goto out;
	 */
	PPC_CMPLDI(b2p[TMP_REG_1], 0);
	PPC_BCC(COND_EQ, out);

	/* goto *(prog->bpf_func + prologue_size); */
	PPC_LD(b2p[TMP_REG_1], b2p[TMP_REG_1], offsetof(struct bpf_prog, bpf_func));
#ifdef PPC64_ELF_ABI_v1
	/* skip past the function descriptor */
	PPC_ADDI(b2p[TMP_REG_1], b2p[TMP_REG_1],
			FUNCTION_DESCR_SIZE + BPF_TAILCALL_PROLOGUE_SIZE);
#else
	PPC_ADDI(b2p[TMP_REG_1], b2p[TMP_REG_1], BPF_TAILCALL_PROLOGUE_SIZE);
#endif
	PPC_MTCTR(b2p[TMP_REG_1]);

	/* tear down stack, restore NVRs, ... */
	bpf_jit_emit_common_epilogue(image, ctx);

	PPC_BCTR();
	/* out: */
}