--- /dev/null
+/*
+ * 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/errno.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 <asm/hwcap.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 ((1 << BPF_MEMWORDS) - 1)
+#define SEEN_MEM_WORD(k) (1 << (k))
+#define SEEN_X (1 << BPF_MEMWORDS)
+#define SEEN_CALL (1 << (BPF_MEMWORDS + 1))
+#define SEEN_SKB (1 << (BPF_MEMWORDS + 2))
+#define SEEN_DATA (1 << (BPF_MEMWORDS + 3))
+
+#define FLAG_NEED_X_RESET (1 << 0)
+
+struct jit_ctx {
+ const struct sk_filter *skf;
+ unsigned idx;
+ unsigned prologue_bytes;
+ int ret0_fp_idx;
+ u32 seen;
+ u32 flags;
+ 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 u64 jit_get_skb_b(struct sk_buff *skb, unsigned offset)
+{
+ u8 ret;
+ int err;
+
+ err = skb_copy_bits(skb, offset, &ret, 1);
+
+ return (u64)err << 32 | ret;
+}
+
+static u64 jit_get_skb_h(struct sk_buff *skb, unsigned offset)
+{
+ u16 ret;
+ int err;
+
+ err = skb_copy_bits(skb, offset, &ret, 2);
+
+ return (u64)err << 32 | ntohs(ret);
+}
+
+static u64 jit_get_skb_w(struct sk_buff *skb, unsigned offset)
+{
+ u32 ret;
+ int err;
+
+ err = skb_copy_bits(skb, offset, &ret, 4);
+
+ return (u64)err << 32 | ntohl(ret);
+}
+
+/*
+ * Wrapper that handles both OABI and EABI and assures Thumb2 interworking
+ * (where the assembly routines like __aeabi_uidiv could cause problems).
+ */
+static u32 jit_udiv(u32 dividend, u32 divisor)
+{
+ return dividend / divisor;
+}
+
+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) ||
+ (ctx->skf->insns[0].code == BPF_S_RET_A))
+ 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_SKB))
+ 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)
+{
+ /* yes, we do waste some stack space IF there are "holes" in the set" */
+ return fls(ctx->seen & SEEN_MEM);
+}
+
+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_SKB))
+ 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->flags & FLAG_NEED_X_RESET)
+ 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 (reg_set) {
+ if (ctx->seen & SEEN_CALL)
+ reg_set |= 1 << ARM_PC;
+ emit(ARM_POP(reg_set), ctx);
+ }
+
+ if (!(ctx->seen & SEEN_CALL))
+ 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_LDR_I(rd, ARM_PC, imm_offset(val, ctx)), ctx);
+#else
+ emit(ARM_MOVW(rd, val & 0xffff), ctx);
+ if (val > 0xffff)
+ emit(ARM_MOVT(rd, val >> 16), 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__ < 6
+
+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);
+}
+
+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+ */
+
+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
+}
+
+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 inline void emit_blx_r(u8 tgt_reg, struct jit_ctx *ctx)
+{
+#if __LINUX_ARM_ARCH__ < 5
+ emit(ARM_MOV_R(ARM_LR, ARM_PC), ctx);
+
+ if (elf_hwcap & HWCAP_THUMB)
+ emit(ARM_BX(tgt_reg), ctx);
+ else
+ emit(ARM_MOV_R(ARM_PC, tgt_reg), ctx);
+#else
+ emit(ARM_BLX_R(tgt_reg), ctx);
+#endif
+}
+
+static inline void emit_udiv(u8 rd, u8 rm, u8 rn, struct jit_ctx *ctx)
+{
+#if __LINUX_ARM_ARCH__ == 7
+ if (elf_hwcap & HWCAP_IDIVA) {
+ emit(ARM_UDIV(rd, rm, rn), ctx);
+ return;
+ }
+#endif
+ if (rm != ARM_R0)
+ emit(ARM_MOV_R(ARM_R0, rm), ctx);
+ if (rn != ARM_R1)
+ emit(ARM_MOV_R(ARM_R1, rn), ctx);
+
+ ctx->seen |= SEEN_CALL;
+ emit_mov_i(ARM_R3, (u32)jit_udiv, ctx);
+ emit_blx_r(ARM_R3, ctx);
+
+ if (rd != ARM_R0)
+ emit(ARM_MOV_R(rd, ARM_R0), ctx);
+}
+
+static inline void update_on_xread(struct jit_ctx *ctx)
+{
+ if (!(ctx->seen & SEEN_X))
+ ctx->flags |= FLAG_NEED_X_RESET;
+
+ ctx->seen |= SEEN_X;
+}
+
+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;
+ 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_SKB;
+ 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:
+ /* the interpreter will deal with the negative K */
+ if ((int)k < 0)
+ return -ENOTSUPP;
+ 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_blx_r(ARM_R3, ctx);
+ /* check the result of skb_copy_bits */
+ emit(ARM_CMP_I(ARM_R1, 0), ctx);
+ emit_err_ret(ARM_COND_NE, 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 | SEEN_SKB;
+ 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;
+ /* the interpreter should deal with the negative K */
+ if (k < 0)
+ return -1;
+ /* 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_mov_i() might generate one or two instructions,
+ * the same holds for emit_blx_r()
+ */
+ _emit(ARM_COND_HI, ARM_B(b_imm(i + 1, ctx) - 2), ctx);
+
+ emit(ARM_MOV_R(ARM_R0, r_skb), ctx);
+ /* r_off is r1 */
+ emit_mov_i(ARM_R3, (u32)jit_get_skb_b, ctx);
+ emit_blx_r(ARM_R3, ctx);
+ /* check the return value of skb_copy_bits */
+ emit(ARM_CMP_I(ARM_R1, 0), ctx);
+ emit_err_ret(ARM_COND_NE, ctx);
+
+ emit(ARM_AND_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:
+ update_on_xread(ctx);
+ ctx->seen |= SEEN_MEM_WORD(k);
+ 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:
+ update_on_xread(ctx);
+ 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:
+ update_on_xread(ctx);
+ 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:
+ update_on_xread(ctx);
+ emit(ARM_MUL(r_A, r_A, r_X), ctx);
+ break;
+ case BPF_S_ALU_DIV_K:
+ /* current k == reciprocal_value(userspace k) */
+ emit_mov_i(r_scratch, k, ctx);
+ /* A = top 32 bits of the product */
+ emit(ARM_UMULL(r_scratch, r_A, r_A, r_scratch), ctx);
+ break;
+ case BPF_S_ALU_DIV_X:
+ update_on_xread(ctx);
+ emit(ARM_CMP_I(r_X, 0), ctx);
+ emit_err_ret(ARM_COND_EQ, ctx);
+ emit_udiv(r_A, r_A, r_X, 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:
+ update_on_xread(ctx);
+ emit(ARM_ORR_R(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:
+ update_on_xread(ctx);
+ 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:
+ update_on_xread(ctx);
+ 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:
+ update_on_xread(ctx);
+ emit(ARM_LSR_R(r_A, r_A, r_X), ctx);
+ break;
+ case BPF_S_ALU_NEG:
+ /* A = -A */
+ emit(ARM_RSB_I(r_A, r_A, 0), ctx);
+ break;
+ case BPF_S_JMP_JA:
+ /* pc += K */
+ emit(ARM_B(b_imm(i + k + 1, ctx)), ctx);
+ break;
+ case BPF_S_JMP_JEQ_K:
+ /* pc += (A == K) ? pc->jt : pc->jf */
+ condt = ARM_COND_EQ;
+ goto cmp_imm;
+ case BPF_S_JMP_JGT_K:
+ /* pc += (A > K) ? pc->jt : pc->jf */
+ condt = ARM_COND_HI;
+ goto cmp_imm;
+ case BPF_S_JMP_JGE_K:
+ /* pc += (A >= K) ? pc->jt : pc->jf */
+ condt = ARM_COND_HS;
+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(condt ^ 1, 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;
+ goto cmp_x;
+ case BPF_S_JMP_JGT_X:
+ /* pc += (A > X) ? pc->jt : pc->jf */
+ condt = ARM_COND_HI;
+ goto cmp_x;
+ case BPF_S_JMP_JGE_X:
+ /* pc += (A >= X) ? pc->jt : pc->jf */
+ condt = ARM_COND_CS;
+cmp_x:
+ update_on_xread(ctx);
+ 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 */
+
+ 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 */
+ update_on_xread(ctx);
+ condt = ARM_COND_NE;
+ 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 */
+ ctx->seen |= SEEN_X;
+ emit(ARM_MOV_R(r_X, r_A), ctx);
+ break;
+ case BPF_S_MISC_TXA:
+ /* A = X */
+ update_on_xread(ctx);
+ emit(ARM_MOV_R(r_A, r_X), ctx);
+ break;
+ case BPF_S_ANC_PROTOCOL:
+ /* A = ntohs(skb->protocol) */
+ ctx->seen |= SEEN_SKB;
+ 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:
+ /* r_scratch = current_thread_info() */
+ OP_IMM3(ARM_BIC, r_scratch, ARM_SP, THREAD_SIZE - 1, ctx);
+ /* A = current_thread_info()->cpu */
+ 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 */
+ ctx->seen |= SEEN_SKB;
+ 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:
+ ctx->seen |= SEEN_SKB;
+ 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:
+ ctx->seen |= SEEN_SKB;
+ 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:
+ ctx->seen |= SEEN_SKB;
+ 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;
+
+ if (!bpf_jit_enable)
+ return;
+
+ 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(max(sizeof(struct work_struct),
+ alloc_size));
+ 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);
+ }
+}
--- /dev/null
+/*
+ * 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
+
+#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_BIC_R 0x01c00000
+#define ARM_INST_BIC_I 0x03c00000
+
+#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_ORR_R 0x01800000
+#define ARM_INST_ORR_I 0x03800000
+
+#define ARM_INST_REV 0x06bf0f30
+#define ARM_INST_REV16 0x06bf0fb0
+
+#define ARM_INST_RSB_I 0x02600000
+
+#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
+
+#define ARM_INST_UDIV 0x0730f010
+
+#define ARM_INST_UMULL 0x00800090
+
+/* 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_BIC_R(rd, rn, rm) _AL3_R(ARM_INST_BIC, rd, rn, rm)
+#define ARM_BIC_I(rd, rn, imm) _AL3_I(ARM_INST_BIC, rd, rn, imm)
+
+#define ARM_B(imm24) (ARM_INST_B | ((imm24) & 0xffffff))
+#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_I(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_I(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_RSB_I(rd, rn, imm) _AL3_I(ARM_INST_RSB, rd, rn, imm)
+
+#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)
+
+#define ARM_UDIV(rd, rn, rm) (ARM_INST_UDIV | (rd) << 16 | (rn) | (rm) << 8)
+
+#define ARM_UMULL(rd_lo, rd_hi, rn, rm) (ARM_INST_UMULL | (rd_hi) << 16 \
+ | (rd_lo) << 12 | (rm) << 8 | rn)
+
+#endif /* PFILTER_OPCODES_ARM_H */
projects / linux-beck.git / commitdiff