arm64: eBPF JIT compiler

The JIT compiler emits A64 instructions. It supports eBPF only.
Legacy BPF is supported thanks to conversion by BPF core.

JIT is enabled in the same way as for other architectures:

	echo 1 > /proc/sys/net/core/bpf_jit_enable

Or for additional compiler output:

	echo 2 > /proc/sys/net/core/bpf_jit_enable

See Documentation/networking/filter.txt for more information.

The implementation passes all 57 tests in lib/test_bpf.c
on ARMv8 Foundation Model :) Also tested by Will on Juno platform.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Documentation/networking/filter.txt

@@ -462,9 +462,9 @@ JIT compiler
 ------------
 
 The Linux kernel has a built-in BPF JIT compiler for x86_64, SPARC, PowerPC,
-ARM and s390 and can be enabled through CONFIG_BPF_JIT. The JIT compiler is
-transparently invoked for each attached filter from user space or for internal
-kernel users if it has been previously enabled by root:
+ARM, ARM64 and s390 and can be enabled through CONFIG_BPF_JIT. The JIT compiler
+is transparently invoked for each attached filter from user space or for
+internal kernel users if it has been previously enabled by root:
 
   echo 1 > /proc/sys/net/core/bpf_jit_enable
 

arch/arm64/Kconfig

@@ -35,6 +35,7 @@ config ARM64
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_TRACEHOOK
+	select HAVE_BPF_JIT
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_CC_STACKPROTECTOR
 	select HAVE_DEBUG_BUGVERBOSE

arch/arm64/Makefile

@@ -47,6 +47,7 @@ endif
 export	TEXT_OFFSET GZFLAGS
 
 core-y		+= arch/arm64/kernel/ arch/arm64/mm/
+core-$(CONFIG_NET) += arch/arm64/net/
 core-$(CONFIG_KVM) += arch/arm64/kvm/
 core-$(CONFIG_XEN) += arch/arm64/xen/
 core-$(CONFIG_CRYPTO) += arch/arm64/crypto/

arch/arm64/net/Makefile

@@ -0,0 +1,4 @@
+#
+# ARM64 networking code
+#
+obj-$(CONFIG_BPF_JIT) += bpf_jit_comp.o

arch/arm64/net/bpf_jit.h

@@ -0,0 +1,169 @@
+/*
+ * BPF JIT compiler for ARM64
+ *
+ * Copyright (C) 2014 Zi Shen Lim <zlim.lnx@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef _BPF_JIT_H
+#define _BPF_JIT_H
+
+#include <asm/insn.h>
+
+/* 5-bit Register Operand */
+#define A64_R(x)	AARCH64_INSN_REG_##x
+#define A64_FP		AARCH64_INSN_REG_FP
+#define A64_LR		AARCH64_INSN_REG_LR
+#define A64_ZR		AARCH64_INSN_REG_ZR
+#define A64_SP		AARCH64_INSN_REG_SP
+
+#define A64_VARIANT(sf) \
+	((sf) ? AARCH64_INSN_VARIANT_64BIT : AARCH64_INSN_VARIANT_32BIT)
+
+/* Compare & branch (immediate) */
+#define A64_COMP_BRANCH(sf, Rt, offset, type) \
+	aarch64_insn_gen_comp_branch_imm(0, offset, Rt, A64_VARIANT(sf), \
+		AARCH64_INSN_BRANCH_COMP_##type)
+#define A64_CBZ(sf, Rt, imm19) A64_COMP_BRANCH(sf, Rt, (imm19) << 2, ZERO)
+
+/* Conditional branch (immediate) */
+#define A64_COND_BRANCH(cond, offset) \
+	aarch64_insn_gen_cond_branch_imm(0, offset, cond)
+#define A64_COND_EQ	AARCH64_INSN_COND_EQ /* == */
+#define A64_COND_NE	AARCH64_INSN_COND_NE /* != */
+#define A64_COND_CS	AARCH64_INSN_COND_CS /* unsigned >= */
+#define A64_COND_HI	AARCH64_INSN_COND_HI /* unsigned > */
+#define A64_COND_GE	AARCH64_INSN_COND_GE /* signed >= */
+#define A64_COND_GT	AARCH64_INSN_COND_GT /* signed > */
+#define A64_B_(cond, imm19) A64_COND_BRANCH(cond, (imm19) << 2)
+
+/* Unconditional branch (immediate) */
+#define A64_BRANCH(offset, type) aarch64_insn_gen_branch_imm(0, offset, \
+	AARCH64_INSN_BRANCH_##type)
+#define A64_B(imm26)  A64_BRANCH((imm26) << 2, NOLINK)
+#define A64_BL(imm26) A64_BRANCH((imm26) << 2, LINK)
+
+/* Unconditional branch (register) */
+#define A64_BLR(Rn) aarch64_insn_gen_branch_reg(Rn, AARCH64_INSN_BRANCH_LINK)
+#define A64_RET(Rn) aarch64_insn_gen_branch_reg(Rn, AARCH64_INSN_BRANCH_RETURN)
+
+/* Load/store register (register offset) */
+#define A64_LS_REG(Rt, Rn, Rm, size, type) \
+	aarch64_insn_gen_load_store_reg(Rt, Rn, Rm, \
+		AARCH64_INSN_SIZE_##size, \
+		AARCH64_INSN_LDST_##type##_REG_OFFSET)
+#define A64_STRB(Wt, Xn, Xm)  A64_LS_REG(Wt, Xn, Xm, 8, STORE)
+#define A64_LDRB(Wt, Xn, Xm)  A64_LS_REG(Wt, Xn, Xm, 8, LOAD)
+#define A64_STRH(Wt, Xn, Xm)  A64_LS_REG(Wt, Xn, Xm, 16, STORE)
+#define A64_LDRH(Wt, Xn, Xm)  A64_LS_REG(Wt, Xn, Xm, 16, LOAD)
+#define A64_STR32(Wt, Xn, Xm) A64_LS_REG(Wt, Xn, Xm, 32, STORE)
+#define A64_LDR32(Wt, Xn, Xm) A64_LS_REG(Wt, Xn, Xm, 32, LOAD)
+#define A64_STR64(Xt, Xn, Xm) A64_LS_REG(Xt, Xn, Xm, 64, STORE)
+#define A64_LDR64(Xt, Xn, Xm) A64_LS_REG(Xt, Xn, Xm, 64, LOAD)
+
+/* Load/store register pair */
+#define A64_LS_PAIR(Rt, Rt2, Rn, offset, ls, type) \
+	aarch64_insn_gen_load_store_pair(Rt, Rt2, Rn, offset, \
+		AARCH64_INSN_VARIANT_64BIT, \
+		AARCH64_INSN_LDST_##ls##_PAIR_##type)
+/* Rn -= 16; Rn[0] = Rt; Rn[8] = Rt2; */
+#define A64_PUSH(Rt, Rt2, Rn) A64_LS_PAIR(Rt, Rt2, Rn, -16, STORE, PRE_INDEX)
+/* Rt = Rn[0]; Rt2 = Rn[8]; Rn += 16; */
+#define A64_POP(Rt, Rt2, Rn)  A64_LS_PAIR(Rt, Rt2, Rn, 16, LOAD, POST_INDEX)
+
+/* Add/subtract (immediate) */
+#define A64_ADDSUB_IMM(sf, Rd, Rn, imm12, type) \
+	aarch64_insn_gen_add_sub_imm(Rd, Rn, imm12, \
+		A64_VARIANT(sf), AARCH64_INSN_ADSB_##type)
+/* Rd = Rn OP imm12 */
+#define A64_ADD_I(sf, Rd, Rn, imm12) A64_ADDSUB_IMM(sf, Rd, Rn, imm12, ADD)
+#define A64_SUB_I(sf, Rd, Rn, imm12) A64_ADDSUB_IMM(sf, Rd, Rn, imm12, SUB)
+/* Rd = Rn */
+#define A64_MOV(sf, Rd, Rn) A64_ADD_I(sf, Rd, Rn, 0)
+
+/* Bitfield move */
+#define A64_BITFIELD(sf, Rd, Rn, immr, imms, type) \
+	aarch64_insn_gen_bitfield(Rd, Rn, immr, imms, \
+		A64_VARIANT(sf), AARCH64_INSN_BITFIELD_MOVE_##type)
+/* Signed, with sign replication to left and zeros to right */
+#define A64_SBFM(sf, Rd, Rn, ir, is) A64_BITFIELD(sf, Rd, Rn, ir, is, SIGNED)
+/* Unsigned, with zeros to left and right */
+#define A64_UBFM(sf, Rd, Rn, ir, is) A64_BITFIELD(sf, Rd, Rn, ir, is, UNSIGNED)
+
+/* Rd = Rn << shift */
+#define A64_LSL(sf, Rd, Rn, shift) ({	\
+	int sz = (sf) ? 64 : 32;	\
+	A64_UBFM(sf, Rd, Rn, (unsigned)-(shift) % sz, sz - 1 - (shift)); \
+})
+/* Rd = Rn >> shift */
+#define A64_LSR(sf, Rd, Rn, shift) A64_UBFM(sf, Rd, Rn, shift, (sf) ? 63 : 31)
+/* Rd = Rn >> shift; signed */
+#define A64_ASR(sf, Rd, Rn, shift) A64_SBFM(sf, Rd, Rn, shift, (sf) ? 63 : 31)
+
+/* Move wide (immediate) */
+#define A64_MOVEW(sf, Rd, imm16, shift, type) \
+	aarch64_insn_gen_movewide(Rd, imm16, shift, \
+		A64_VARIANT(sf), AARCH64_INSN_MOVEWIDE_##type)
+/* Rd = Zeros (for MOVZ);
+ * Rd |= imm16 << shift (where shift is {0, 16, 32, 48});
+ * Rd = ~Rd; (for MOVN); */
+#define A64_MOVN(sf, Rd, imm16, shift) A64_MOVEW(sf, Rd, imm16, shift, INVERSE)
+#define A64_MOVZ(sf, Rd, imm16, shift) A64_MOVEW(sf, Rd, imm16, shift, ZERO)
+#define A64_MOVK(sf, Rd, imm16, shift) A64_MOVEW(sf, Rd, imm16, shift, KEEP)
+
+/* Add/subtract (shifted register) */
+#define A64_ADDSUB_SREG(sf, Rd, Rn, Rm, type) \
+	aarch64_insn_gen_add_sub_shifted_reg(Rd, Rn, Rm, 0, \
+		A64_VARIANT(sf), AARCH64_INSN_ADSB_##type)
+/* Rd = Rn OP Rm */
+#define A64_ADD(sf, Rd, Rn, Rm)  A64_ADDSUB_SREG(sf, Rd, Rn, Rm, ADD)
+#define A64_SUB(sf, Rd, Rn, Rm)  A64_ADDSUB_SREG(sf, Rd, Rn, Rm, SUB)
+#define A64_SUBS(sf, Rd, Rn, Rm) A64_ADDSUB_SREG(sf, Rd, Rn, Rm, SUB_SETFLAGS)
+/* Rd = -Rm */
+#define A64_NEG(sf, Rd, Rm) A64_SUB(sf, Rd, A64_ZR, Rm)
+/* Rn - Rm; set condition flags */
+#define A64_CMP(sf, Rn, Rm) A64_SUBS(sf, A64_ZR, Rn, Rm)
+
+/* Data-processing (1 source) */
+#define A64_DATA1(sf, Rd, Rn, type) aarch64_insn_gen_data1(Rd, Rn, \
+	A64_VARIANT(sf), AARCH64_INSN_DATA1_##type)
+/* Rd = BSWAPx(Rn) */
+#define A64_REV16(sf, Rd, Rn) A64_DATA1(sf, Rd, Rn, REVERSE_16)
+#define A64_REV32(sf, Rd, Rn) A64_DATA1(sf, Rd, Rn, REVERSE_32)
+#define A64_REV64(Rd, Rn)     A64_DATA1(1, Rd, Rn, REVERSE_64)
+
+/* Data-processing (2 source) */
+/* Rd = Rn OP Rm */
+#define A64_UDIV(sf, Rd, Rn, Rm) aarch64_insn_gen_data2(Rd, Rn, Rm, \
+	A64_VARIANT(sf), AARCH64_INSN_DATA2_UDIV)
+
+/* Data-processing (3 source) */
+/* Rd = Ra + Rn * Rm */
+#define A64_MADD(sf, Rd, Ra, Rn, Rm) aarch64_insn_gen_data3(Rd, Ra, Rn, Rm, \
+	A64_VARIANT(sf), AARCH64_INSN_DATA3_MADD)
+/* Rd = Rn * Rm */
+#define A64_MUL(sf, Rd, Rn, Rm) A64_MADD(sf, Rd, A64_ZR, Rn, Rm)
+
+/* Logical (shifted register) */
+#define A64_LOGIC_SREG(sf, Rd, Rn, Rm, type) \
+	aarch64_insn_gen_logical_shifted_reg(Rd, Rn, Rm, 0, \
+		A64_VARIANT(sf), AARCH64_INSN_LOGIC_##type)
+/* Rd = Rn OP Rm */
+#define A64_AND(sf, Rd, Rn, Rm)  A64_LOGIC_SREG(sf, Rd, Rn, Rm, AND)
+#define A64_ORR(sf, Rd, Rn, Rm)  A64_LOGIC_SREG(sf, Rd, Rn, Rm, ORR)
+#define A64_EOR(sf, Rd, Rn, Rm)  A64_LOGIC_SREG(sf, Rd, Rn, Rm, EOR)
+#define A64_ANDS(sf, Rd, Rn, Rm) A64_LOGIC_SREG(sf, Rd, Rn, Rm, AND_SETFLAGS)
+/* Rn & Rm; set condition flags */
+#define A64_TST(sf, Rn, Rm) A64_ANDS(sf, A64_ZR, Rn, Rm)
+
+#endif /* _BPF_JIT_H */