Patchwork ARM: net: JIT compiler for packet filters

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Submitter Mircea Gherzan
Date Dec. 18, 2011, 11:48 p.m.
Message ID <1324252115-15774-1-git-send-email-mgherzan@gmail.com>
Download mbox | patch
Permalink /patch/132139/
State Superseded
Delegated to: David Miller
Headers show

Comments

Mircea Gherzan - Dec. 18, 2011, 11:48 p.m.
Based of Matt Evans's PPC64 implementation.

Supports only ARM mode with EABI.

Supports both little and big endian. Depends on the support for
unaligned loads on ARMv7. Does not support all the BPF opcodes
that deal with ancillary data. The scratch memory of the filter
lives on the stack.

Enabled in the same way as for x86-64 and PPC64:

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

A value greater than 1 enables opcode output.

Signed-off-by: Mircea Gherzan <mgherzan@gmail.com>
---
 arch/arm/Kconfig          |    1 +
 arch/arm/Makefile         |    1 +
 arch/arm/net/Makefile     |    3 +
 arch/arm/net/bpf_jit_32.c |  840 +++++++++++++++++++++++++++++++++++++++++++++
 arch/arm/net/bpf_jit_32.h |  174 ++++++++++
 5 files changed, 1019 insertions(+), 0 deletions(-)
 create mode 100644 arch/arm/net/Makefile
 create mode 100644 arch/arm/net/bpf_jit_32.c
 create mode 100644 arch/arm/net/bpf_jit_32.h

Patch

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index abba5b8..ea65c41 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -30,6 +30,7 @@  config ARM
 	select HAVE_SPARSE_IRQ
 	select GENERIC_IRQ_SHOW
 	select CPU_PM if (SUSPEND || CPU_IDLE)
+	select HAVE_BPF_JIT if (!THUMB2_KERNEL && AEABI)
 	help
 	  The ARM series is a line of low-power-consumption RISC chip designs
 	  licensed by ARM Ltd and targeted at embedded applications and
diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index dfcf3b0..8810a10 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -255,6 +255,7 @@  core-$(CONFIG_VFP)		+= arch/arm/vfp/
 
 # If we have a machine-specific directory, then include it in the build.
 core-y				+= arch/arm/kernel/ arch/arm/mm/ arch/arm/common/
+core-y				+= arch/arm/net/
 core-y				+= $(machdirs) $(platdirs)
 
 drivers-$(CONFIG_OPROFILE)      += arch/arm/oprofile/
diff --git a/arch/arm/net/Makefile b/arch/arm/net/Makefile
new file mode 100644
index 0000000..c2c1084
--- /dev/null
+++ b/arch/arm/net/Makefile
@@ -0,0 +1,3 @@ 
+# ARM-specific networking code
+
+obj-$(CONFIG_BPF_JIT) += bpf_jit_32.o
diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
new file mode 100644
index 0000000..4d4c2a0
--- /dev/null
+++ b/arch/arm/net/bpf_jit_32.c
@@ -0,0 +1,840 @@ 
+/*
+ * Just-In-Time compiler for BPF filters on 32bit ARM
+ *
+ * Copyright (c) 2011 Mircea Gherzan <mgherzan@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; version 2 of the License.
+ */
+
+#include <linux/bitops.h>
+#include <linux/compiler.h>
+#include <linux/filter.h>
+#include <linux/moduleloader.h>
+#include <linux/netdevice.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <asm/cacheflush.h>
+
+#include "bpf_jit_32.h"
+
+/*
+ * ABI:
+ *
+ * r0	scratch register
+ * r4	BPF register A
+ * r5	BPF register X
+ * r6	pointer to the skb
+ * r7	skb->data
+ * r8	skb_headlen(skb)
+ */
+
+#define r_scratch	ARM_R0
+/* r1-r3 are (also) used for the unaligned loads on the non-ARMv7 slowpath */
+#define r_off		ARM_R1
+#define r_A		ARM_R4
+#define r_X		ARM_R5
+#define r_skb		ARM_R6
+#define r_skb_data	ARM_R7
+#define r_skb_hl	ARM_R8
+
+#define SCRATCH_SP_OFFSET	0
+#define SCRATCH_OFF(k)		(SCRATCH_SP_OFFSET + (k))
+
+#define SEEN_MEM		0xff
+#define SEEN_MEM_WORD(k)	(1 << (k))
+#define SEEN_X			(1 << 16)
+#define SEEN_CALL		(1 << 17)
+#define SEEN_DATA		(1 << 18)
+#define SEEN_LEN		(1 << 19)
+
+struct jit_ctx {
+	const struct sk_filter *skf;
+	unsigned idx;
+	unsigned prologue_bytes;
+	int ret0_fp_idx;
+	u32 seen;
+	u32 *offsets;
+	u32 *target;
+#if __LINUX_ARM_ARCH__ < 7
+	u16 epilogue_bytes;
+	u16 imm_count;
+	u32 *imms;
+#endif
+};
+
+int bpf_jit_enable __read_mostly;
+
+static u8 jit_get_skb_b(struct sk_buff *skb, unsigned offset)
+{
+	u8 ret;
+	skb_copy_bits(skb, offset, &ret, 1);
+	return ret;
+}
+
+static u16 jit_get_skb_h(struct sk_buff *skb, unsigned offset)
+{
+	u16 ret;
+	skb_copy_bits(skb, offset, &ret, 2);
+	return ntohs(ret);
+}
+
+static u32 jit_get_skb_w(struct sk_buff *skb, unsigned offset)
+{
+	u32 ret;
+	skb_copy_bits(skb, offset, &ret, 4);
+	return ntohl(ret);
+}
+
+static inline void _emit(int cond, u32 inst, struct jit_ctx *ctx)
+{
+	if (ctx->target != NULL)
+		ctx->target[ctx->idx] = inst | (cond << 28);
+
+	ctx->idx++;
+}
+
+/*
+ * Emit an instruction that will be executed unconditionally.
+ */
+static inline void emit(u32 inst, struct jit_ctx *ctx)
+{
+	_emit(ARM_COND_AL, inst, ctx);
+}
+
+static u16 saved_regs(struct jit_ctx *ctx)
+{
+	u16 ret = 0;
+
+	if (ctx->skf->len > 1)
+		ret |= 1 << r_A;
+
+#ifdef CONFIG_FRAME_POINTER
+	ret |= (1 << ARM_FP) | (1 << ARM_IP) | (1 << ARM_LR) | (1 << ARM_PC);
+#else
+	if (ctx->seen & SEEN_CALL)
+		ret |= 1 << ARM_LR;
+#endif
+	if (ctx->seen & (SEEN_DATA | SEEN_LEN))
+		ret |= 1 << r_skb;
+	if (ctx->seen & SEEN_DATA)
+		ret |= (1 << r_skb_data) | (1 << r_skb_hl);
+	if (ctx->seen & SEEN_X)
+		ret |= 1 << r_X;
+
+	return ret;
+}
+
+static inline int mem_words_used(struct jit_ctx *ctx)
+{
+	u32 words = ctx->seen & SEEN_MEM;
+	/* yes, we do waste some stack space IF there are "holes" in the set" */
+	return (words) ? 16 - __builtin_clz(words) : 0;
+}
+
+static inline bool is_load_to_a(u16 inst)
+{
+	switch (inst) {
+	case BPF_S_LD_W_LEN:
+	case BPF_S_LD_W_ABS:
+	case BPF_S_LD_H_ABS:
+	case BPF_S_LD_B_ABS:
+	case BPF_S_ANC_CPU:
+	case BPF_S_ANC_IFINDEX:
+	case BPF_S_ANC_MARK:
+	case BPF_S_ANC_PROTOCOL:
+	case BPF_S_ANC_RXHASH:
+	case BPF_S_ANC_QUEUE:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static void build_prologue(struct jit_ctx *ctx)
+{
+	u16 reg_set = saved_regs(ctx);
+	u16 first_inst = ctx->skf->insns[0].code;
+	u16 off;
+
+#ifdef CONFIG_FRAME_POINTER
+	emit(ARM_MOV_R(ARM_IP, ARM_SP), ctx);
+	emit(ARM_PUSH(reg_set), ctx);
+	emit(ARM_SUB_I(ARM_FP, ARM_IP, 4), ctx);
+#else
+	if (reg_set)
+		emit(ARM_PUSH(reg_set), ctx);
+#endif
+
+	if (ctx->seen & (SEEN_DATA | SEEN_LEN))
+		emit(ARM_MOV_R(r_skb, ARM_R0), ctx);
+
+	if (ctx->seen & SEEN_DATA) {
+		off = offsetof(struct sk_buff, data);
+		emit(ARM_LDR_I(r_skb_data, r_skb, off), ctx);
+		/* headlen = len - data_len */
+		off = offsetof(struct sk_buff, len);
+		emit(ARM_LDR_I(r_skb_hl, r_skb, off), ctx);
+		off = offsetof(struct sk_buff, data_len);
+		emit(ARM_LDR_I(r_scratch, r_skb, off), ctx);
+		emit(ARM_SUB_R(r_skb_hl, r_skb_hl, r_scratch), ctx);
+	}
+
+	if (ctx->seen & SEEN_X)
+		emit(ARM_MOV_I(r_X, 0), ctx);
+
+	/* do not leak kernel data to userspace */
+	if ((first_inst != BPF_S_RET_K) && !(is_load_to_a(first_inst)))
+		emit(ARM_MOV_I(r_A, 0), ctx);
+
+	/* stack space for the BPF_MEM words */
+	if (ctx->seen & SEEN_MEM)
+		emit(ARM_SUB_I(ARM_SP, ARM_SP, mem_words_used(ctx) * 4), ctx);
+}
+
+static void build_epilogue(struct jit_ctx *ctx)
+{
+	u16 reg_set = saved_regs(ctx);
+
+	if (ctx->seen & SEEN_MEM)
+		emit(ARM_ADD_I(ARM_SP, ARM_SP, mem_words_used(ctx) * 4), ctx);
+
+	reg_set &= ~(1 << ARM_LR);
+
+#ifdef CONFIG_FRAME_POINTER
+	/* the first instruction of the prologue was: mov ip, sp */
+	reg_set &= ~(1 << ARM_IP);
+	reg_set |= (1 << ARM_SP);
+	emit(ARM_LDM(ARM_SP, reg_set), ctx);
+#else
+	if (ctx->seen)
+		emit(ARM_POP(reg_set | (1 << ARM_PC)), ctx);
+	else
+		emit(ARM_BX(ARM_LR), ctx);
+#endif
+}
+
+static int16_t imm8m(u32 x)
+{
+	u32 rot;
+
+	for (rot = 0; rot < 16; rot++)
+		if ((x & ~ror32(0xff, 2 * rot)) == 0)
+			return rol32(x, 2 * rot) | (rot << 8);
+
+	return -1;
+}
+
+#if __LINUX_ARM_ARCH__ < 7
+static u16 imm_offset(u32 k, struct jit_ctx *ctx)
+{
+	unsigned i = 0, offset;
+	u16 imm;
+
+	/* on the "fake" run we just count them (duplicates included) */
+	if (ctx->target == NULL) {
+		ctx->imm_count++;
+		return 0;
+	}
+
+	while ((i < ctx->imm_count) && ctx->imms[i]) {
+		if (ctx->imms[i] == k)
+			break;
+		i++;
+	}
+
+	if (ctx->imms[i] == 0)
+		ctx->imms[i] = k;
+
+	/* constants go just after the epilogue */
+	offset =  ctx->offsets[ctx->skf->len];
+	offset += ctx->prologue_bytes;
+	offset += ctx->epilogue_bytes;
+	offset += i * 4;
+
+	ctx->target[offset / 4] = k;
+
+	/* PC in ARM mode == address of the instruction + 8 */
+	imm = offset - (8 + ctx->idx * 4);
+
+	return imm;
+}
+#endif /* __LINUX_ARM_ARCH__ */
+
+
+/*
+ * Move an immediate that's not an imm8m to a core register.
+ */
+static inline void emit_mov_i_no8m(int rd, u32 val, struct jit_ctx *ctx)
+{
+#if __LINUX_ARM_ARCH__ >= 7
+	emit(ARM_MOVW(rd, val & 0xffff), ctx);
+	if (val > 0xffff)
+		emit(ARM_MOVT(rd, val >> 16), ctx);
+#else
+	emit(ARM_LDR_I(rd, ARM_PC, imm_offset(val, ctx)), ctx);
+#endif
+}
+
+static inline void emit_mov_i(int rd, u32 val, struct jit_ctx *ctx)
+{
+	int imm12 = imm8m(val);
+
+	if (imm12 >= 0)
+		emit(ARM_MOV_I(rd, imm12), ctx);
+	else
+		emit_mov_i_no8m(rd, val, ctx);
+}
+
+#if __LINUX_ARM_ARCH__ < 7
+
+static void emit_load_be32(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx)
+{
+	_emit(cond, ARM_LDRB_I(ARM_R3, r_addr, 1), ctx);
+	_emit(cond, ARM_LDRB_I(ARM_R1, r_addr, 0), ctx);
+	_emit(cond, ARM_LDRB_I(ARM_R2, r_addr, 3), ctx);
+	_emit(cond, ARM_LSL_I(ARM_R3, ARM_R3, 16), ctx);
+	_emit(cond, ARM_LDRB_I(ARM_R0, r_addr, 2), ctx);
+	_emit(cond, ARM_ORR_S(ARM_R3, ARM_R3, ARM_R1, SRTYPE_LSL, 24), ctx);
+	_emit(cond, ARM_ORR_R(ARM_R3, ARM_R3, ARM_R2), ctx);
+	_emit(cond, ARM_ORR_S(r_res, ARM_R3, ARM_R0, SRTYPE_LSL, 8), ctx);
+}
+
+static void emit_load_be16(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx)
+{
+	_emit(cond, ARM_LDRB_I(ARM_R1, r_addr, 0), ctx);
+	_emit(cond, ARM_LDRB_I(ARM_R2, r_addr, 1), ctx);
+	_emit(cond, ARM_ORR_S(r_res, ARM_R2, ARM_R1, SRTYPE_LSL, 8), ctx);
+}
+
+
+#else  /* ARMv7 */
+
+static void emit_load_be32(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx)
+{
+	_emit(cond, ARM_LDR_I(r_res, r_addr, 0), ctx);
+#ifdef __LITTLE_ENDIAN
+	_emit(cond, ARM_REV(r_res, r_res), ctx);
+#endif
+}
+
+static void emit_load_be16(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx)
+{
+	_emit(cond, ARM_LDRH_I(r_res, r_addr, 0), ctx);
+#ifdef __LITTLE_ENDIAN
+	_emit(cond, ARM_REV16(r_res, r_res), ctx);
+#endif
+}
+
+
+#endif /* __LINUX_ARM_ARCH__ < 6 */
+
+#if __LINUX_ARM_ARCH__ >= 6
+
+static inline void emit_swap16(u8 r_dst, u8 r_src, struct jit_ctx *ctx)
+{
+	emit(ARM_LSL_R(ARM_R1, r_src, 8), ctx);
+	emit(ARM_ORR_S(r_dst, ARM_R1, r_src, SRTYPE_LSL, 8), ctx);
+	emit(ARM_LSL_I(r_dst, r_dst, 8), ctx);
+	emit(ARM_LSL_R(r_dst, r_dst, 8), ctx);
+}
+
+#else /* ARMv6 or ARMv7 */
+
+static inline void emit_swap16(u8 r_dst __maybe_unused,
+			       u8 r_src __maybe_unused,
+			       struct jit_ctx *ctx __maybe_unused)
+{
+#ifdef __LITTLE_ENDIAN
+	emit(ARM_REV16(r_dst, r_src), ctx);
+#endif
+}
+
+#endif /* __LINUX_ARM_ARCH__ < 6 */
+
+
+/* Compute the immediate value for a PC-relative branch. */
+static inline u32 b_imm(unsigned tgt, struct jit_ctx *ctx)
+{
+	u32 imm;
+
+	if (ctx->target == NULL)
+		return 0;
+	/*
+	 * BPF allows only forward jumps and the offset of the target is
+	 * still the one computed during the first pass.
+	 */
+	imm  = ctx->offsets[tgt] + ctx->prologue_bytes - (ctx->idx * 4 + 8);
+
+	return imm >> 2;
+}
+
+#define OP_IMM3(op, r1, r2, imm_val, ctx)				\
+	do {								\
+		imm12 = imm8m(imm_val);					\
+		if (imm12 < 0) {					\
+			emit_mov_i_no8m(r_scratch, imm_val, ctx);	\
+			emit(op ## _R((r1), (r2), r_scratch), ctx);	\
+		} else {						\
+			emit(op ## _I((r1), (r2), imm12), ctx);		\
+		}							\
+	} while (0)
+
+static inline void emit_err_ret(u8 cond, struct jit_ctx *ctx)
+{
+	if (ctx->ret0_fp_idx >= 0) {
+		_emit(cond, ARM_B(b_imm(ctx->ret0_fp_idx, ctx)), ctx);
+		/* NOP to keep the size constant between passes */
+		emit(ARM_MOV_R(ARM_R0, ARM_R0), ctx);
+	} else {
+		_emit(cond, ARM_MOV_I(ARM_R0, 0), ctx);
+		_emit(cond, ARM_B(b_imm(ctx->skf->len, ctx)), ctx);
+	}
+}
+
+static int build_body(struct jit_ctx *ctx)
+{
+	void  *load_func[] = {jit_get_skb_b, jit_get_skb_h, jit_get_skb_w};
+	const struct sk_filter *prog = ctx->skf;
+	const struct sock_filter *inst;
+	unsigned i, load_order, off, condt, condf;
+	int imm12;
+	u32 k;
+
+	for (i = 0; i < prog->len; i++) {
+		inst = &(prog->insns[i]);
+		/* K as an immediate value operand */
+		k = inst->k;
+
+		/* compute offsets only in the fake pass */
+		if (ctx->target == NULL)
+			ctx->offsets[i] = ctx->idx * 4;
+
+		switch (inst->code) {
+		case BPF_S_LD_IMM:
+			emit_mov_i(r_A, k, ctx);
+			break;
+		case BPF_S_LD_W_LEN:
+			ctx->seen |= SEEN_LEN;
+			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
+			emit(ARM_LDR_I(r_A, r_skb,
+				       offsetof(struct sk_buff, len)), ctx);
+			break;
+		case BPF_S_LD_MEM:
+			/* A = scratch[k] */
+			ctx->seen |= SEEN_MEM_WORD(k);
+			emit(ARM_LDR_I(r_A, ARM_SP, SCRATCH_OFF(k)), ctx);
+			break;
+		case BPF_S_LD_W_ABS:
+			load_order = 2;
+			goto load;
+		case BPF_S_LD_H_ABS:
+			load_order = 1;
+			goto load;
+		case BPF_S_LD_B_ABS:
+			load_order = 0;
+load:
+			emit_mov_i(r_off, k, ctx);
+load_common:
+			ctx->seen |= SEEN_DATA | SEEN_CALL;
+
+			if (load_order > 0) {
+				emit(ARM_SUB_I(r_scratch, r_skb_hl,
+					       1 << load_order), ctx);
+				emit(ARM_CMP_R(r_scratch, r_off), ctx);
+				condt = ARM_COND_HS;
+			} else {
+				emit(ARM_CMP_R(r_skb_hl, r_off), ctx);
+				condt = ARM_COND_HI;
+			}
+
+			_emit(condt, ARM_ADD_R(r_scratch, r_off, r_skb_data),
+			      ctx);
+
+			if (load_order == 0)
+				_emit(condt, ARM_LDRB_I(r_A, r_scratch, 0),
+				      ctx);
+			else if (load_order == 1)
+				emit_load_be16(condt, r_A, r_scratch, ctx);
+			else if (load_order == 2)
+				emit_load_be32(condt, r_A, r_scratch, ctx);
+
+			_emit(condt, ARM_B(b_imm(i + 1, ctx)), ctx);
+
+			/* the slowpath */
+			emit_mov_i(ARM_R3, (u32)load_func[load_order], ctx);
+			emit(ARM_MOV_R(ARM_R0, r_skb), ctx);
+			/* the offset is already in R1 */
+			emit(ARM_BLX_R(ARM_R3), ctx);
+			emit(ARM_MOV_R(r_A, ARM_R0), ctx);
+			break;
+		case BPF_S_LD_W_IND:
+			load_order = 2;
+			goto load_ind;
+		case BPF_S_LD_H_IND:
+			load_order = 1;
+			goto load_ind;
+		case BPF_S_LD_B_IND:
+			load_order = 0;
+load_ind:
+			OP_IMM3(ARM_ADD, r_off, r_X, k, ctx);
+			goto load_common;
+		case BPF_S_LDX_IMM:
+			ctx->seen |= SEEN_X;
+			emit_mov_i(r_X, k, ctx);
+			break;
+		case BPF_S_LDX_W_LEN:
+			ctx->seen |= SEEN_X;
+			emit(ARM_LDR_I(r_X, r_skb,
+				       offsetof(struct sk_buff, len)), ctx);
+			break;
+		case BPF_S_LDX_MEM:
+			ctx->seen |= SEEN_X | SEEN_MEM_WORD(k);
+			emit(ARM_LDR_I(r_X, ARM_SP, SCRATCH_OFF(k)), ctx);
+			break;
+		case BPF_S_LDX_B_MSH:
+			/* x = ((*(frame + k)) & 0xf) << 2; */
+			ctx->seen |= SEEN_X | SEEN_DATA | SEEN_CALL;
+			/* offset in r1: we might have to take the slow path */
+			emit_mov_i(r_off, k, ctx);
+			emit(ARM_CMP_R(r_skb_hl, r_off), ctx);
+
+			/* load in r0: common with the slowpath */
+			_emit(ARM_COND_HI, ARM_LDRB_R(ARM_R0, r_skb_data,
+						      ARM_R1), ctx);
+			_emit(ARM_COND_HI, ARM_B((3 * 4 - 8) >> 2), ctx);
+
+			emit(ARM_MOV_R(ARM_R0, r_skb), ctx);
+			/* r_off is r1 */
+			emit(ARM_MOV_I(ARM_R3, (u32)jit_get_skb_b), ctx);
+			emit(ARM_BLX_R(ARM_R3), ctx);
+
+			emit(ARM_ORR_I(r_X, ARM_R0, 0x00f), ctx);
+			emit(ARM_LSL_I(r_X, r_X, 2), ctx);
+			break;
+		case BPF_S_ST:
+			ctx->seen |= SEEN_MEM_WORD(k);
+			emit(ARM_STR_I(r_A, ARM_SP, SCRATCH_OFF(k)), ctx);
+			break;
+		case BPF_S_STX:
+			ctx->seen |= SEEN_MEM_WORD(k) | SEEN_X;
+			emit(ARM_STR_I(r_X, ARM_SP, SCRATCH_OFF(k)), ctx);
+			break;
+		case BPF_S_ALU_ADD_K:
+			/* A += K */
+			OP_IMM3(ARM_ADD, r_A, r_A, k, ctx);
+			break;
+		case BPF_S_ALU_ADD_X:
+			ctx->seen |= SEEN_X;
+			emit(ARM_ADD_R(r_A, r_A, r_X), ctx);
+			break;
+		case BPF_S_ALU_SUB_K:
+			/* A -= K */
+			OP_IMM3(ARM_SUB, r_A, r_A, k, ctx);
+			break;
+		case BPF_S_ALU_SUB_X:
+			ctx->seen |= SEEN_X;
+			emit(ARM_SUB_R(r_A, r_A, r_X), ctx);
+			break;
+		case BPF_S_ALU_MUL_K:
+			/* A *= K */
+			emit_mov_i(r_scratch, k, ctx);
+			emit(ARM_MUL(r_A, r_A, r_scratch), ctx);
+			break;
+		case BPF_S_ALU_MUL_X:
+			ctx->seen |= SEEN_X;
+			emit(ARM_MUL(r_A, r_A, r_X), ctx);
+			break;
+		case BPF_S_ALU_DIV_K:
+			/* K is not zero, it was previously checked */
+			emit_mov_i(ARM_R1, k, ctx);
+			goto div;
+		case BPF_S_ALU_DIV_X:
+			ctx->seen |= SEEN_X;
+			emit(ARM_CMP_I(r_X, 0), ctx);
+			emit_err_ret(ARM_COND_EQ, ctx);
+			emit(ARM_MOV_R(ARM_R1, r_X), ctx);
+div:
+			ctx->seen |= SEEN_CALL;
+
+			emit(ARM_MOV_R(ARM_R0, r_A), ctx);
+			emit_mov_i(r_scratch, (u32)__aeabi_uidiv, ctx);
+			emit(ARM_BLX_R(r_scratch), ctx);
+			emit(ARM_MOV_R(r_A, ARM_R0), ctx);
+			break;
+		case BPF_S_ALU_OR_K:
+			/* A |= K */
+			OP_IMM3(ARM_ORR, r_A, r_A, k, ctx);
+			break;
+		case BPF_S_ALU_OR_X:
+			ctx->seen |= SEEN_X;
+			emit(ARM_ORR_I(r_A, r_A, r_X), ctx);
+			break;
+		case BPF_S_ALU_AND_K:
+			/* A &= K */
+			OP_IMM3(ARM_AND, r_A, r_A, k, ctx);
+			break;
+		case BPF_S_ALU_AND_X:
+			ctx->seen |= SEEN_X;
+			emit(ARM_AND_R(r_A, r_A, r_X), ctx);
+			break;
+		case BPF_S_ALU_LSH_K:
+			if (unlikely(k > 31))
+				return -1;
+			emit(ARM_LSL_I(r_A, r_A, k), ctx);
+			break;
+		case BPF_S_ALU_LSH_X:
+			ctx->seen |= SEEN_X;
+			emit(ARM_LSL_R(r_A, r_A, r_X), ctx);
+			break;
+		case BPF_S_ALU_RSH_K:
+			if (unlikely(k > 31))
+				return -1;
+			emit(ARM_LSR_I(r_A, r_A, k), ctx);
+			break;
+		case BPF_S_ALU_RSH_X:
+			ctx->seen |= SEEN_X;
+			emit(ARM_LSR_R(r_A, r_A, r_X), ctx);
+			break;
+		case BPF_S_JMP_JA:
+			/* pc += K */
+			emit(ARM_B(b_imm(i + k, ctx)), ctx);
+			break;
+		case BPF_S_JMP_JEQ_K:
+			/* pc += (A == K) ? pc->jt : pc->jf */
+			condt   = ARM_COND_EQ;
+			condf  = ARM_COND_NE;
+			goto cmp_imm;
+		case BPF_S_JMP_JGT_K:
+			/* pc += (A > K) ? pc->jt : pc->jf */
+			condt   = ARM_COND_HI;
+			condf  = ARM_COND_LS;
+			goto cmp_imm;
+		case BPF_S_JMP_JGE_K:
+			/* pc += (A >= K) ? pc->jt : pc->jf */
+			condt   = ARM_COND_HI;
+			condf  = ARM_COND_LS;
+			/* (x >= y) IFF (x > y - 1) */
+			if (unlikely(k == 0))
+				return -1;
+			k--;
+cmp_imm:
+			imm12 = imm8m(k);
+			if (imm12 < 0) {
+				emit_mov_i_no8m(r_scratch, k, ctx);
+				emit(ARM_CMP_R(r_A, r_scratch), ctx);
+			} else {
+				emit(ARM_CMP_I(r_A, imm12), ctx);
+			}
+cond_jump:
+			if (inst->jt)
+				_emit(condt, ARM_B(b_imm(i + inst->jt + 1,
+						   ctx)), ctx);
+			if (inst->jf)
+				_emit(condf, ARM_B(b_imm(i + inst->jf + 1,
+						   ctx)), ctx);
+			break;
+		case BPF_S_JMP_JEQ_X:
+			/* pc += (A == X) ? pc->jt : pc->jf */
+			condt   = ARM_COND_EQ;
+			condf  = ARM_COND_NE;
+			goto cmp_x;
+		case BPF_S_JMP_JGT_X:
+			/* pc += (A > X) ? pc->jt : pc->jf */
+			condt   = ARM_COND_HI;
+			condf  = ARM_COND_LS;
+			goto cmp_x;
+		case BPF_S_JMP_JGE_X:
+			/* pc += (A >= X) ? pc->jt : pc->jf */
+			condt   = ARM_COND_CS;
+			condf  = ARM_COND_CC;
+cmp_x:
+			ctx->seen |= SEEN_X;
+			emit(ARM_CMP_R(r_A, r_X), ctx);
+			goto cond_jump;
+		case BPF_S_JMP_JSET_K:
+			/* pc += (A & K) ? pc->jt : pc->jf */
+			condt  = ARM_COND_NE;
+			/* not set iff all zeroes iff Z==1 iff EQ */
+			condf  = ARM_COND_EQ;
+
+			imm12 = imm8m(k);
+			if (imm12 < 0) {
+				emit_mov_i_no8m(r_scratch, k, ctx);
+				emit(ARM_TST_R(r_A, r_scratch), ctx);
+			} else {
+				emit(ARM_TST_I(r_A, imm12), ctx);
+			}
+			goto cond_jump;
+		case BPF_S_JMP_JSET_X:
+			/* pc += (A & X) ? pc->jt : pc->jf */
+			condt  = ARM_COND_NE;
+			condf  = ARM_COND_EQ;
+			emit(ARM_TST_R(r_A, r_X), ctx);
+			goto cond_jump;
+		case BPF_S_RET_A:
+			emit(ARM_MOV_R(ARM_R0, r_A), ctx);
+			goto b_epilogue;
+		case BPF_S_RET_K:
+			if ((k == 0) && (ctx->ret0_fp_idx < 0))
+				ctx->ret0_fp_idx = i;
+			emit_mov_i(ARM_R0, k, ctx);
+b_epilogue:
+			if (i != ctx->skf->len - 1)
+				emit(ARM_B(b_imm(prog->len, ctx)), ctx);
+			break;
+		case BPF_S_MISC_TAX:
+			/* X = A */
+			emit(ARM_MOV_R(r_X, r_A), ctx);
+			break;
+		case BPF_S_MISC_TXA:
+			/* A = X */
+			emit(ARM_MOV_R(r_A, r_X), ctx);
+			break;
+		case BPF_S_ANC_PROTOCOL:
+			/* A = ntohs(skb->protocol) */
+			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
+						  protocol) != 2);
+			off = offsetof(struct sk_buff, protocol);
+			emit(ARM_LDRH_I(r_scratch, r_skb, off), ctx);
+			emit_swap16(r_A, r_scratch, ctx);
+			break;
+		case BPF_S_ANC_CPU:
+			/* A = current_thread_info()->cpu */
+			emit_mov_i(r_scratch, (~(THREAD_SIZE - 1)), ctx);
+			emit(ARM_ADD_R(r_scratch, ARM_SP, r_scratch), ctx);
+
+			BUILD_BUG_ON(FIELD_SIZEOF(struct thread_info, cpu) != 4);
+			off = offsetof(struct thread_info, cpu);
+			emit(ARM_LDR_I(r_A, r_scratch, off), ctx);
+			break;
+		case BPF_S_ANC_IFINDEX:
+			/* A = skb->dev->ifindex */
+			off = offsetof(struct sk_buff, dev);
+			emit(ARM_LDR_I(r_scratch, r_skb, off), ctx);
+
+			emit(ARM_CMP_I(r_scratch, 0), ctx);
+			emit_err_ret(ARM_COND_EQ, ctx);
+
+			BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
+						  ifindex) != 4);
+			off = offsetof(struct net_device, ifindex);
+			emit(ARM_LDR_I(r_A, r_scratch, off), ctx);
+			break;
+		case BPF_S_ANC_MARK:
+			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
+			off = offsetof(struct sk_buff, mark);
+			emit(ARM_LDR_I(r_A, r_skb, off), ctx);
+			break;
+		case BPF_S_ANC_RXHASH:
+			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
+			off = offsetof(struct sk_buff, rxhash);
+			emit(ARM_LDR_I(r_A, r_skb, off), ctx);
+			break;
+		case BPF_S_ANC_QUEUE:
+			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
+						  queue_mapping) != 2);
+			BUILD_BUG_ON(offsetof(struct sk_buff,
+					      queue_mapping) > 0xff);
+			off = offsetof(struct sk_buff, queue_mapping);
+			emit(ARM_LDRH_I(r_A, r_skb, off), ctx);
+			break;
+		default:
+			return -1;
+		}
+	}
+
+	/* compute offsets only during the first pass */
+	if (ctx->target == NULL)
+		ctx->offsets[i] = ctx->idx * 4;
+
+	return 0;
+}
+
+
+void bpf_jit_compile(struct sk_filter *fp)
+{
+	struct jit_ctx ctx;
+	unsigned tmp_idx;
+	unsigned alloc_size;
+
+	memset(&ctx, 0, sizeof(ctx));
+	ctx.skf		= fp;
+	ctx.ret0_fp_idx = -1;
+
+	ctx.offsets = kzalloc(GFP_KERNEL, 4 * (ctx.skf->len + 1));
+	if (ctx.offsets == NULL)
+		return;
+
+	/* fake pass to fill in the ctx->seen */
+	if (unlikely(build_body(&ctx)))
+		goto out;
+
+	tmp_idx = ctx.idx;
+	build_prologue(&ctx);
+	ctx.prologue_bytes = (ctx.idx - tmp_idx) * 4;
+
+#if __LINUX_ARM_ARCH__ < 7
+	tmp_idx = ctx.idx;
+	build_epilogue(&ctx);
+	ctx.epilogue_bytes = (ctx.idx - tmp_idx) * 4;
+
+	ctx.idx += ctx.imm_count;
+	if (ctx.imm_count) {
+		ctx.imms = kzalloc(GFP_KERNEL, 4 * ctx.imm_count);
+		if (ctx.imms == NULL)
+			goto out;
+	}
+#else
+	/* there's nothing after the epilogue on ARMv7 */
+	build_epilogue(&ctx);
+#endif
+
+	alloc_size = 4 * ctx.idx;
+	ctx.target = module_alloc(alloc_size > sizeof(struct work_struct) ?
+				  alloc_size : sizeof(struct work_struct));
+	if (unlikely(ctx.target == NULL))
+		goto out;
+
+	ctx.idx = 0;
+	build_prologue(&ctx);
+	build_body(&ctx);
+	build_epilogue(&ctx);
+
+	flush_icache_range((u32)ctx.target, (u32)(ctx.target + ctx.idx));
+
+#if __LINUX_ARM_ARCH__ < 7
+	if (ctx.imm_count)
+		kfree(ctx.imms);
+#endif
+
+	if (bpf_jit_enable > 1)
+		print_hex_dump(KERN_INFO, "BPF JIT code: ",
+			       DUMP_PREFIX_ADDRESS, 16, 4, ctx.target,
+			       alloc_size, false);
+
+	fp->bpf_func = (void *)ctx.target;
+
+out:
+	kfree(ctx.offsets);
+	return;
+}
+
+static void bpf_jit_free_worker(struct work_struct *work)
+{
+	module_free(NULL, work);
+}
+
+void bpf_jit_free(struct sk_filter *fp)
+{
+	struct work_struct *work;
+
+	if (fp->bpf_func != sk_run_filter) {
+		work = (struct work_struct *)fp->bpf_func;
+
+		INIT_WORK(work, bpf_jit_free_worker);
+		schedule_work(work);
+	}
+}
+
diff --git a/arch/arm/net/bpf_jit_32.h b/arch/arm/net/bpf_jit_32.h
new file mode 100644
index 0000000..de68a51
--- /dev/null
+++ b/arch/arm/net/bpf_jit_32.h
@@ -0,0 +1,174 @@ 
+/*
+ * Just-In-Time compiler for BPF filters on 32bit ARM
+ *
+ * Copyright (c) 2011 Mircea Gherzan <mgherzan@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; version 2 of the License.
+ */
+
+#ifndef PFILTER_OPCODES_ARM_H
+#define PFILTER_OPCODES_ARM_H
+
+extern void *__aeabi_uidiv;
+
+#define ARM_R0	0
+#define ARM_R1	1
+#define ARM_R2	2
+#define ARM_R3	3
+#define ARM_R4	4
+#define ARM_R5	5
+#define ARM_R6	6
+#define ARM_R7	7
+#define ARM_R8	8
+#define ARM_R9	9
+#define ARM_R10	10
+#define ARM_FP	11
+#define ARM_IP	12
+#define ARM_SP	13
+#define ARM_LR	14
+#define ARM_PC	15
+
+#define ARM_COND_EQ		0x0
+#define ARM_COND_NE		0x1
+#define ARM_COND_CS		0x2
+#define ARM_COND_HS		ARM_COND_CS
+#define ARM_COND_CC		0x3
+#define ARM_COND_LO		ARM_COND_CC
+#define ARM_COND_MI		0x4
+#define ARM_COND_PL		0x5
+#define ARM_COND_VS		0x6
+#define ARM_COND_VC		0x7
+#define ARM_COND_HI		0x8
+#define ARM_COND_LS		0x9
+#define ARM_COND_GE		0xa
+#define ARM_COND_LT		0xb
+#define ARM_COND_GT		0xc
+#define ARM_COND_LE		0xd
+#define ARM_COND_AL		0xe
+
+/* register shift types */
+#define SRTYPE_LSL		0
+#define SRTYPE_LSR		1
+#define SRTYPE_ASR		2
+#define SRTYPE_ROR		3
+
+#define ARM_INST_ADD_R		0x00800000
+#define ARM_INST_ADD_I		0x02800000
+
+#define ARM_INST_AND_R		0x00000000
+#define ARM_INST_AND_I		0x02000000
+
+#define ARM_INST_B		0x0a000000
+#define ARM_INST_BX		0x012FFF10
+#define ARM_INST_BLX_R		0x012fff30
+
+#define ARM_INST_CMP_R		0x01500000
+#define ARM_INST_CMP_I		0x03500000
+
+#define ARM_INST_LDRB_I		0x05d00000
+#define ARM_INST_LDRB_R		0x07d00000
+#define ARM_INST_LDRH_I		0x01d000b0
+#define ARM_INST_LDR_I		0x05900000
+
+#define ARM_INST_LDM		0x08900000
+
+#define ARM_INST_LSL_I		0x01a00000
+#define ARM_INST_LSL_R		0x01a00010
+
+#define ARM_INST_LSR_I		0x01a00020
+#define ARM_INST_LSR_R		0x01a00030
+
+#define ARM_INST_MOV_R		0x01a00000
+#define ARM_INST_MOV_I		0x03a00000
+#define ARM_INST_MOVW		0x03000000
+#define ARM_INST_MOVT		0x03400000
+
+#define ARM_INST_MUL		0x00000090
+
+#define ARM_INST_POP		0x08bd0000
+#define ARM_INST_PUSH		0x092d0000
+
+#define ARM_INST_REV		0x06bf0f30
+#define ARM_INST_REV16		0x06bf0fb0
+
+#define ARM_INST_ORR_R		0x01800000
+#define ARM_INST_ORR_I		0x03800000
+
+#define ARM_INST_SUB_R		0x00400000
+#define ARM_INST_SUB_I		0x02400000
+
+#define ARM_INST_STR_I		0x05800000
+
+#define ARM_INST_TST_R		0x01100000
+#define ARM_INST_TST_I		0x03100000
+
+
+/* register */
+#define _AL3_R(op, rd, rn, rm)	((op ## _R) | (rd) << 12 | (rn) << 16 | (rm))
+/* immediate */
+#define _AL3_I(op, rd, rn, imm)	((op ## _I) | (rd) << 12 | (rn) << 16 | (imm))
+
+#define ARM_ADD_R(rd, rn, rm)	_AL3_R(ARM_INST_ADD, rd, rn, rm)
+#define ARM_ADD_I(rd, rn, imm)	_AL3_I(ARM_INST_ADD, rd, rn, imm)
+
+#define ARM_AND_R(rd, rn, rm)	_AL3_R(ARM_INST_AND, rd, rn, rm)
+#define ARM_AND_I(rd, rn, imm)	_AL3_I(ARM_INST_AND, rd, rn, imm)
+
+#define ARM_B(imm24)		(ARM_INST_B | (imm24))
+#define ARM_BX(rm)		(ARM_INST_BX | (rm))
+#define ARM_BLX_R(rm)		(ARM_INST_BLX_R | (rm))
+
+#define ARM_CMP_R(rn, rm)	_AL3_R(ARM_INST_CMP, 0, rn, rm)
+#define ARM_CMP_I(rn, imm)	_AL3_I(ARM_INST_CMP, 0, rn, imm)
+
+#define ARM_LDR_I(rt, rn, off)	(ARM_INST_LDR_I | (rt) << 12 | (rn) << 16 \
+				 | (off))
+#define ARM_LDRB_I(rt, rn, off)	(ARM_INST_LDRB_I | (rt) << 12 | (rn) << 16 \
+				 | (off))
+#define ARM_LDRB_R(rt, rn, rm)	(ARM_INST_LDRB_R | (rt) << 12 | (rn) << 16 \
+				 | (rm))
+#define ARM_LDRH_I(rt, rn, off)	(ARM_INST_LDRH_I | (rt) << 12 | (rn) << 16 \
+				 | (((off) & 0xf0) << 4) | ((off) & 0xf))
+
+#define ARM_LDM(rn, regs)	(ARM_INST_LDM | (rn) << 16 | (regs))
+
+#define ARM_LSL_R(rd, rn, rm)	(_AL3_R(ARM_INST_LSL, rd, 0, rn) | (rm) << 8)
+#define ARM_LSL_I(rd, rn, imm)	(_AL3_R(ARM_INST_LSL, rd, 0, rn) | (imm) << 7)
+
+#define ARM_LSR_R(rd, rn, rm)	(_AL3_R(ARM_INST_LSR, rd, 0, rn) | (rm) << 8)
+#define ARM_LSR_I(rd, rn, imm)	(_AL3_R(ARM_INST_LSR, rd, 0, rn) | (imm) << 7)
+
+#define ARM_MOV_R(rd, rm)	_AL3_R(ARM_INST_MOV, rd, 0, rm)
+#define ARM_MOV_I(rd, imm)	_AL3_I(ARM_INST_MOV, rd, 0, imm)
+
+#define ARM_MOVW(rd, imm)	\
+	(ARM_INST_MOVW | ((imm) >> 12) << 16 | (rd) << 12 | ((imm) & 0x0fff))
+
+#define ARM_MOVT(rd, imm)	\
+	(ARM_INST_MOVT | ((imm) >> 12) << 16 | (rd) << 12 | ((imm) & 0x0fff))
+
+#define ARM_MUL(rd, rm, rn)	(ARM_INST_MUL | (rd) << 16 | (rm) << 8 | (rn))
+
+#define ARM_POP(regs)		(ARM_INST_POP | (regs))
+#define ARM_PUSH(regs)		(ARM_INST_PUSH | (regs))
+
+#define ARM_ORR_R(rd, rn, rm)	_AL3_R(ARM_INST_ORR, rd, rn, rm)
+#define ARM_ORR_I(rd, rn, imm)	_AL3_I(ARM_INST_ORR, rd, rn, imm)
+#define ARM_ORR_S(rd, rn, rm, type, rs)	\
+	(ARM_ORR_R(rd, rn, rm) | (type) << 5 | (rs) << 7)
+
+#define ARM_REV(rd, rm)		(ARM_INST_REV | (rd) << 12 | (rm))
+#define ARM_REV16(rd, rm)	(ARM_INST_REV16 | (rd) << 12 | (rm))
+
+#define ARM_SUB_R(rd, rn, rm)	_AL3_R(ARM_INST_SUB, rd, rn, rm)
+#define ARM_SUB_I(rd, rn, imm)	_AL3_I(ARM_INST_SUB, rd, rn, imm)
+
+#define ARM_STR_I(rt, rn, off)	(ARM_INST_STR_I | (rt) << 12 | (rn) << 16 \
+				 | (off))
+
+#define ARM_TST_R(rn, rm)	_AL3_R(ARM_INST_TST, 0, rn, rm)
+#define ARM_TST_I(rn, imm)	_AL3_I(ARM_INST_TST, 0, rn, imm)
+
+#endif /* PFILTER_OPCODES_ARM_H */