diff options
Diffstat (limited to '')
| -rw-r--r-- | arch/mips/net/bpf_jit.c | 1270 |
1 files changed, 1270 insertions, 0 deletions
diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c new file mode 100644 index 000000000000..0af88622c619 --- /dev/null +++ b/arch/mips/net/bpf_jit.c @@ -0,0 +1,1270 @@ +/* + * Just-In-Time compiler for BPF filters on MIPS + * + * Copyright (c) 2014 Imagination Technologies Ltd. + * Author: Markos Chandras <markos.chandras@imgtec.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/if_vlan.h> +#include <linux/moduleloader.h> +#include <linux/netdevice.h> +#include <linux/string.h> +#include <linux/slab.h> +#include <linux/types.h> +#include <asm/asm.h> +#include <asm/bitops.h> +#include <asm/cacheflush.h> +#include <asm/cpu-features.h> +#include <asm/uasm.h> + +#include "bpf_jit.h" + +/* ABI + * r_skb_hl SKB header length + * r_data SKB data pointer + * r_off Offset + * r_A BPF register A + * r_X BPF register X + * r_skb *skb + * r_M *scratch memory + * r_skb_len SKB length + * + * On entry (*bpf_func)(*skb, *filter) + * a0 = MIPS_R_A0 = skb; + * a1 = MIPS_R_A1 = filter; + * + * Stack + * ... + * M[15] + * M[14] + * M[13] + * ... + * M[0] <-- r_M + * saved reg k-1 + * saved reg k-2 + * ... + * saved reg 0 <-- r_sp + * <no argument area> + * + * Packet layout + * + * <--------------------- len ------------------------> + * <--skb-len(r_skb_hl)-->< ----- skb->data_len ------> + * ---------------------------------------------------- + * | skb->data | + * ---------------------------------------------------- + */ + +#define ptr typeof(unsigned long) + +#define SCRATCH_OFF(k) (4 * (k)) + +/* JIT flags */ +#define SEEN_CALL (1 << BPF_MEMWORDS) +#define SEEN_SREG_SFT (BPF_MEMWORDS + 1) +#define SEEN_SREG_BASE (1 << SEEN_SREG_SFT) +#define SEEN_SREG(x) (SEEN_SREG_BASE << (x)) +#define SEEN_OFF SEEN_SREG(2) +#define SEEN_A SEEN_SREG(3) +#define SEEN_X SEEN_SREG(4) +#define SEEN_SKB SEEN_SREG(5) +#define SEEN_MEM SEEN_SREG(6) +/* SEEN_SK_DATA also implies skb_hl an skb_len */ +#define SEEN_SKB_DATA (SEEN_SREG(7) | SEEN_SREG(1) | SEEN_SREG(0)) + +/* Arguments used by JIT */ +#define ARGS_USED_BY_JIT 2 /* only applicable to 64-bit */ + +#define SBIT(x) (1 << (x)) /* Signed version of BIT() */ + +/** + * struct jit_ctx - JIT context + * @skf: The sk_filter + * @prologue_bytes: Number of bytes for prologue + * @idx: Instruction index + * @flags: JIT flags + * @offsets: Instruction offsets + * @target: Memory location for the compiled filter + */ +struct jit_ctx { + const struct bpf_prog *skf; + unsigned int prologue_bytes; + u32 idx; + u32 flags; + u32 *offsets; + u32 *target; +}; + + +static inline int optimize_div(u32 *k) +{ + /* power of 2 divides can be implemented with right shift */ + if (!(*k & (*k-1))) { + *k = ilog2(*k); + return 1; + } + + return 0; +} + +static inline void emit_jit_reg_move(ptr dst, ptr src, struct jit_ctx *ctx); + +/* Simply emit the instruction if the JIT memory space has been allocated */ +#define emit_instr(ctx, func, ...) \ +do { \ + if ((ctx)->target != NULL) { \ + u32 *p = &(ctx)->target[ctx->idx]; \ + uasm_i_##func(&p, ##__VA_ARGS__); \ + } \ + (ctx)->idx++; \ +} while (0) + +/* + * Similar to emit_instr but it must be used when we need to emit + * 32-bit or 64-bit instructions + */ +#define emit_long_instr(ctx, func, ...) \ +do { \ + if ((ctx)->target != NULL) { \ + u32 *p = &(ctx)->target[ctx->idx]; \ + UASM_i_##func(&p, ##__VA_ARGS__); \ + } \ + (ctx)->idx++; \ +} while (0) + +/* Determine if immediate is within the 16-bit signed range */ +static inline bool is_range16(s32 imm) +{ + return !(imm >= SBIT(15) || imm < -SBIT(15)); +} + +static inline void emit_addu(unsigned int dst, unsigned int src1, + unsigned int src2, struct jit_ctx *ctx) +{ + emit_instr(ctx, addu, dst, src1, src2); +} + +static inline void emit_nop(struct jit_ctx *ctx) +{ + emit_instr(ctx, nop); +} + +/* Load a u32 immediate to a register */ +static inline void emit_load_imm(unsigned int dst, u32 imm, struct jit_ctx *ctx) +{ + if (ctx->target != NULL) { + /* addiu can only handle s16 */ + if (!is_range16(imm)) { + u32 *p = &ctx->target[ctx->idx]; + uasm_i_lui(&p, r_tmp_imm, (s32)imm >> 16); + p = &ctx->target[ctx->idx + 1]; + uasm_i_ori(&p, dst, r_tmp_imm, imm & 0xffff); + } else { + u32 *p = &ctx->target[ctx->idx]; + uasm_i_addiu(&p, dst, r_zero, imm); + } + } + ctx->idx++; + + if (!is_range16(imm)) + ctx->idx++; +} + +static inline void emit_or(unsigned int dst, unsigned int src1, + unsigned int src2, struct jit_ctx *ctx) +{ + emit_instr(ctx, or, dst, src1, src2); +} + +static inline void emit_ori(unsigned int dst, unsigned src, u32 imm, + struct jit_ctx *ctx) +{ + if (imm >= BIT(16)) { + emit_load_imm(r_tmp, imm, ctx); + emit_or(dst, src, r_tmp, ctx); + } else { + emit_instr(ctx, ori, dst, src, imm); + } +} + +static inline void emit_daddiu(unsigned int dst, unsigned int src, + int imm, struct jit_ctx *ctx) +{ + /* + * Only used for stack, so the imm is relatively small + * and it fits in 15-bits + */ + emit_instr(ctx, daddiu, dst, src, imm); +} + +static inline void emit_addiu(unsigned int dst, unsigned int src, + u32 imm, struct jit_ctx *ctx) +{ + if (!is_range16(imm)) { + emit_load_imm(r_tmp, imm, ctx); + emit_addu(dst, r_tmp, src, ctx); + } else { + emit_instr(ctx, addiu, dst, src, imm); + } +} + +static inline void emit_and(unsigned int dst, unsigned int src1, + unsigned int src2, struct jit_ctx *ctx) +{ + emit_instr(ctx, and, dst, src1, src2); +} + +static inline void emit_andi(unsigned int dst, unsigned int src, + u32 imm, struct jit_ctx *ctx) +{ + /* If imm does not fit in u16 then load it to register */ + if (imm >= BIT(16)) { + emit_load_imm(r_tmp, imm, ctx); + emit_and(dst, src, r_tmp, ctx); + } else { + emit_instr(ctx, andi, dst, src, imm); + } +} + +static inline void emit_xor(unsigned int dst, unsigned int src1, + unsigned int src2, struct jit_ctx *ctx) +{ + emit_instr(ctx, xor, dst, src1, src2); +} + +static inline void emit_xori(ptr dst, ptr src, u32 imm, struct jit_ctx *ctx) +{ + /* If imm does not fit in u16 then load it to register */ + if (imm >= BIT(16)) { + emit_load_imm(r_tmp, imm, ctx); + emit_xor(dst, src, r_tmp, ctx); + } else { + emit_instr(ctx, xori, dst, src, imm); + } +} + +static inline void emit_stack_offset(int offset, struct jit_ctx *ctx) +{ + emit_long_instr(ctx, ADDIU, r_sp, r_sp, offset); +} + +static inline void emit_subu(unsigned int dst, unsigned int src1, + unsigned int src2, struct jit_ctx *ctx) +{ + emit_instr(ctx, subu, dst, src1, src2); +} + +static inline void emit_neg(unsigned int reg, struct jit_ctx *ctx) +{ + emit_subu(reg, r_zero, reg, ctx); +} + +static inline void emit_sllv(unsigned int dst, unsigned int src, + unsigned int sa, struct jit_ctx *ctx) +{ + emit_instr(ctx, sllv, dst, src, sa); +} + +static inline void emit_sll(unsigned int dst, unsigned int src, + unsigned int sa, struct jit_ctx *ctx) +{ + /* sa is 5-bits long */ + if (sa >= BIT(5)) + /* Shifting >= 32 results in zero */ + emit_jit_reg_move(dst, r_zero, ctx); + else + emit_instr(ctx, sll, dst, src, sa); +} + +static inline void emit_srlv(unsigned int dst, unsigned int src, + unsigned int sa, struct jit_ctx *ctx) +{ + emit_instr(ctx, srlv, dst, src, sa); +} + +static inline void emit_srl(unsigned int dst, unsigned int src, + unsigned int sa, struct jit_ctx *ctx) +{ + /* sa is 5-bits long */ + if (sa >= BIT(5)) + /* Shifting >= 32 results in zero */ + emit_jit_reg_move(dst, r_zero, ctx); + else + emit_instr(ctx, srl, dst, src, sa); +} + +static inline void emit_slt(unsigned int dst, unsigned int src1, + unsigned int src2, struct jit_ctx *ctx) +{ + emit_instr(ctx, slt, dst, src1, src2); +} + +static inline void emit_sltu(unsigned int dst, unsigned int src1, + unsigned int src2, struct jit_ctx *ctx) +{ + emit_instr(ctx, sltu, dst, src1, src2); +} + +static inline void emit_sltiu(unsigned dst, unsigned int src, + unsigned int imm, struct jit_ctx *ctx) +{ + /* 16 bit immediate */ + if (!is_range16((s32)imm)) { + emit_load_imm(r_tmp, imm, ctx); + emit_sltu(dst, src, r_tmp, ctx); + } else { + emit_instr(ctx, sltiu, dst, src, imm); + } + +} + +/* Store register on the stack */ +static inline void emit_store_stack_reg(ptr reg, ptr base, + unsigned int offset, + struct jit_ctx *ctx) +{ + emit_long_instr(ctx, SW, reg, offset, base); +} + +static inline void emit_store(ptr reg, ptr base, unsigned int offset, + struct jit_ctx *ctx) +{ + emit_instr(ctx, sw, reg, offset, base); +} + +static inline void emit_load_stack_reg(ptr reg, ptr base, + unsigned int offset, + struct jit_ctx *ctx) +{ + emit_long_instr(ctx, LW, reg, offset, base); +} + +static inline void emit_load(unsigned int reg, unsigned int base, + unsigned int offset, struct jit_ctx *ctx) +{ + emit_instr(ctx, lw, reg, offset, base); +} + +static inline void emit_load_byte(unsigned int reg, unsigned int base, + unsigned int offset, struct jit_ctx *ctx) +{ + emit_instr(ctx, lb, reg, offset, base); +} + +static inline void emit_half_load(unsigned int reg, unsigned int base, + unsigned int offset, struct jit_ctx *ctx) +{ + emit_instr(ctx, lh, reg, offset, base); +} + +static inline void emit_half_load_unsigned(unsigned int reg, unsigned int base, + unsigned int offset, struct jit_ctx *ctx) +{ + emit_instr(ctx, lhu, reg, offset, base); +} + +static inline void emit_mul(unsigned int dst, unsigned int src1, + unsigned int src2, struct jit_ctx *ctx) +{ + emit_instr(ctx, mul, dst, src1, src2); +} + +static inline void emit_div(unsigned int dst, unsigned int src, + struct jit_ctx *ctx) +{ + if (ctx->target != NULL) { + u32 *p = &ctx->target[ctx->idx]; + uasm_i_divu(&p, dst, src); + p = &ctx->target[ctx->idx + 1]; + uasm_i_mflo(&p, dst); + } + ctx->idx += 2; /* 2 insts */ +} + +static inline void emit_mod(unsigned int dst, unsigned int src, + struct jit_ctx *ctx) +{ + if (ctx->target != NULL) { + u32 *p = &ctx->target[ctx->idx]; + uasm_i_divu(&p, dst, src); + p = &ctx->target[ctx->idx + 1]; + uasm_i_mfhi(&p, dst); + } + ctx->idx += 2; /* 2 insts */ +} + +static inline void emit_dsll(unsigned int dst, unsigned int src, + unsigned int sa, struct jit_ctx *ctx) +{ + emit_instr(ctx, dsll, dst, src, sa); +} + +static inline void emit_dsrl32(unsigned int dst, unsigned int src, + unsigned int sa, struct jit_ctx *ctx) +{ + emit_instr(ctx, dsrl32, dst, src, sa); +} + +static inline void emit_wsbh(unsigned int dst, unsigned int src, + struct jit_ctx *ctx) +{ + emit_instr(ctx, wsbh, dst, src); +} + +/* load pointer to register */ +static inline void emit_load_ptr(unsigned int dst, unsigned int src, + int imm, struct jit_ctx *ctx) +{ + /* src contains the base addr of the 32/64-pointer */ + emit_long_instr(ctx, LW, dst, imm, src); +} + +/* load a function pointer to register */ +static inline void emit_load_func(unsigned int reg, ptr imm, + struct jit_ctx *ctx) +{ + if (IS_ENABLED(CONFIG_64BIT)) { + /* At this point imm is always 64-bit */ + emit_load_imm(r_tmp, (u64)imm >> 32, ctx); + emit_dsll(r_tmp_imm, r_tmp, 16, ctx); /* left shift by 16 */ + emit_ori(r_tmp, r_tmp_imm, (imm >> 16) & 0xffff, ctx); + emit_dsll(r_tmp_imm, r_tmp, 16, ctx); /* left shift by 16 */ + emit_ori(reg, r_tmp_imm, imm & 0xffff, ctx); + } else { + emit_load_imm(reg, imm, ctx); + } +} + +/* Move to real MIPS register */ +static inline void emit_reg_move(ptr dst, ptr src, struct jit_ctx *ctx) +{ + emit_long_instr(ctx, ADDU, dst, src, r_zero); +} + +/* Move to JIT (32-bit) register */ +static inline void emit_jit_reg_move(ptr dst, ptr src, struct jit_ctx *ctx) +{ + emit_addu(dst, src, r_zero, ctx); +} + +/* Compute the immediate value for PC-relative branches. */ +static inline u32 b_imm(unsigned int tgt, struct jit_ctx *ctx) +{ + if (ctx->target == NULL) + return 0; + + /* + * We want a pc-relative branch. We only do forward branches + * so tgt is always after pc. tgt is the instruction offset + * we want to jump to. + + * Branch on MIPS: + * I: target_offset <- sign_extend(offset) + * I+1: PC += target_offset (delay slot) + * + * ctx->idx currently points to the branch instruction + * but the offset is added to the delay slot so we need + * to subtract 4. + */ + return ctx->offsets[tgt] - + (ctx->idx * 4 - ctx->prologue_bytes) - 4; +} + +static inline void emit_bcond(int cond, unsigned int reg1, unsigned int reg2, + unsigned int imm, struct jit_ctx *ctx) +{ + if (ctx->target != NULL) { + u32 *p = &ctx->target[ctx->idx]; + + switch (cond) { + case MIPS_COND_EQ: + uasm_i_beq(&p, reg1, reg2, imm); + break; + case MIPS_COND_NE: + uasm_i_bne(&p, reg1, reg2, imm); + break; + case MIPS_COND_ALL: + uasm_i_b(&p, imm); + break; + default: + pr_warn("%s: Unhandled branch conditional: %d\n", + __func__, cond); + } + } + ctx->idx++; +} + +static inline void emit_b(unsigned int imm, struct jit_ctx *ctx) +{ + emit_bcond(MIPS_COND_ALL, r_zero, r_zero, imm, ctx); +} + +static inline void emit_jalr(unsigned int link, unsigned int reg, + struct jit_ctx *ctx) +{ + emit_instr(ctx, jalr, link, reg); +} + +static inline void emit_jr(unsigned int reg, struct jit_ctx *ctx) +{ + emit_instr(ctx, jr, reg); +} + +static inline u16 align_sp(unsigned int num) +{ + /* Double word alignment for 32-bit, quadword for 64-bit */ + unsigned int align = IS_ENABLED(CONFIG_64BIT) ? 16 : 8; + num = (num + (align - 1)) & -align; + return num; +} + +static void save_bpf_jit_regs(struct jit_ctx *ctx, unsigned offset) +{ + int i = 0, real_off = 0; + u32 sflags, tmp_flags; + + /* Adjust the stack pointer */ + if (offset) + emit_stack_offset(-align_sp(offset), ctx); + + tmp_flags = sflags = ctx->flags >> SEEN_SREG_SFT; + /* sflags is essentially a bitmap */ + while (tmp_flags) { + if ((sflags >> i) & 0x1) { + emit_store_stack_reg(MIPS_R_S0 + i, r_sp, real_off, + ctx); + real_off += SZREG; + } + i++; + tmp_flags >>= 1; + } + + /* save return address */ + if (ctx->flags & SEEN_CALL) { + emit_store_stack_reg(r_ra, r_sp, real_off, ctx); + real_off += SZREG; + } + + /* Setup r_M leaving the alignment gap if necessary */ + if (ctx->flags & SEEN_MEM) { + if (real_off % (SZREG * 2)) + real_off += SZREG; + emit_long_instr(ctx, ADDIU, r_M, r_sp, real_off); + } +} + +static void restore_bpf_jit_regs(struct jit_ctx *ctx, + unsigned int offset) +{ + int i, real_off = 0; + u32 sflags, tmp_flags; + + tmp_flags = sflags = ctx->flags >> SEEN_SREG_SFT; + /* sflags is a bitmap */ + i = 0; + while (tmp_flags) { + if ((sflags >> i) & 0x1) { + emit_load_stack_reg(MIPS_R_S0 + i, r_sp, real_off, + ctx); + real_off += SZREG; + } + i++; + tmp_flags >>= 1; + } + + /* restore return address */ + if (ctx->flags & SEEN_CALL) + emit_load_stack_reg(r_ra, r_sp, real_off, ctx); + + /* Restore the sp and discard the scrach memory */ + if (offset) + emit_stack_offset(align_sp(offset), ctx); +} + +static unsigned int get_stack_depth(struct jit_ctx *ctx) +{ + int sp_off = 0; + + + /* How may s* regs do we need to preserved? */ + sp_off += hweight32(ctx->flags >> SEEN_SREG_SFT) * SZREG; + + if (ctx->flags & SEEN_MEM) + sp_off += 4 * BPF_MEMWORDS; /* BPF_MEMWORDS are 32-bit */ + + if (ctx->flags & SEEN_CALL) + sp_off += SZREG; /* Space for our ra register */ + + return sp_off; +} + +static void build_prologue(struct jit_ctx *ctx) +{ + int sp_off; + + /* Calculate the total offset for the stack pointer */ + sp_off = get_stack_depth(ctx); + save_bpf_jit_regs(ctx, sp_off); + + if (ctx->flags & SEEN_SKB) + emit_reg_move(r_skb, MIPS_R_A0, ctx); + + if (ctx->flags & SEEN_SKB_DATA) { + /* Load packet length */ + emit_load(r_skb_len, r_skb, offsetof(struct sk_buff, len), + ctx); + emit_load(r_tmp, r_skb, offsetof(struct sk_buff, data_len), + ctx); + /* Load the data pointer */ + emit_load_ptr(r_skb_data, r_skb, + offsetof(struct sk_buff, data), ctx); + /* Load the header length */ + emit_subu(r_skb_hl, r_skb_len, r_tmp, ctx); + } + + if (ctx->flags & SEEN_X) + emit_jit_reg_move(r_X, r_zero, ctx); + + /* + * Do not leak kernel data to userspace, we only need to clear + * r_A if it is ever used. In fact if it is never used, we + * will not save/restore it, so clearing it in this case would + * corrupt the state of the caller. + */ + if (bpf_needs_clear_a(&ctx->skf->insns[0]) && + (ctx->flags & SEEN_A)) + emit_jit_reg_move(r_A, r_zero, ctx); +} + +static void build_epilogue(struct jit_ctx *ctx) +{ + unsigned int sp_off; + + /* Calculate the total offset for the stack pointer */ + + sp_off = get_stack_depth(ctx); + restore_bpf_jit_regs(ctx, sp_off); + + /* Return */ + emit_jr(r_ra, ctx); + emit_nop(ctx); +} + +#define CHOOSE_LOAD_FUNC(K, func) \ + ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative : func) : \ + func##_positive) + +static int build_body(struct jit_ctx *ctx) +{ + const struct bpf_prog *prog = ctx->skf; + const struct sock_filter *inst; + unsigned int i, off, condt; + u32 k, b_off __maybe_unused; + u8 (*sk_load_func)(unsigned long *skb, int offset); + + for (i = 0; i < prog->len; i++) { + u16 code; + + inst = &(prog->insns[i]); + pr_debug("%s: code->0x%02x, jt->0x%x, jf->0x%x, k->0x%x\n", + __func__, inst->code, inst->jt, inst->jf, inst->k); + k = inst->k; + code = bpf_anc_helper(inst); + + if (ctx->target == NULL) + ctx->offsets[i] = ctx->idx * 4; + + switch (code) { + case BPF_LD | BPF_IMM: + /* A <- k ==> li r_A, k */ + ctx->flags |= SEEN_A; + emit_load_imm(r_A, k, ctx); + break; + case BPF_LD | BPF_W | BPF_LEN: + BUILD_BUG_ON(sizeof_field(struct sk_buff, len) != 4); + /* A <- len ==> lw r_A, offset(skb) */ + ctx->flags |= SEEN_SKB | SEEN_A; + off = offsetof(struct sk_buff, len); + emit_load(r_A, r_skb, off, ctx); + break; + case BPF_LD | BPF_MEM: + /* A <- M[k] ==> lw r_A, offset(M) */ + ctx->flags |= SEEN_MEM | SEEN_A; + emit_load(r_A, r_M, SCRATCH_OFF(k), ctx); + break; + case BPF_LD | BPF_W | BPF_ABS: + /* A <- P[k:4] */ + sk_load_func = CHOOSE_LOAD_FUNC(k, sk_load_word); + goto load; + case BPF_LD | BPF_H | BPF_ABS: + /* A <- P[k:2] */ + sk_load_func = CHOOSE_LOAD_FUNC(k, sk_load_half); + goto load; + case BPF_LD | BPF_B | BPF_ABS: + /* A <- P[k:1] */ + sk_load_func = CHOOSE_LOAD_FUNC(k, sk_load_byte); +load: + emit_load_imm(r_off, k, ctx); +load_common: + ctx->flags |= SEEN_CALL | SEEN_OFF | + SEEN_SKB | SEEN_A | SEEN_SKB_DATA; + + emit_load_func(r_s0, (ptr)sk_load_func, ctx); + emit_reg_move(MIPS_R_A0, r_skb, ctx); + emit_jalr(MIPS_R_RA, r_s0, ctx); + /* Load second argument to delay slot */ + emit_reg_move(MIPS_R_A1, r_off, ctx); + /* Check the error value */ + emit_bcond(MIPS_COND_EQ, r_ret, 0, b_imm(i + 1, ctx), + ctx); + /* Load return register on DS for failures */ + emit_reg_move(r_ret, r_zero, ctx); + /* Return with error */ + emit_b(b_imm(prog->len, ctx), ctx); + emit_nop(ctx); + break; + case BPF_LD | BPF_W | BPF_IND: + /* A <- P[X + k:4] */ + sk_load_func = sk_load_word; + goto load_ind; + case BPF_LD | BPF_H | BPF_IND: + /* A <- P[X + k:2] */ + sk_load_func = sk_load_half; + goto load_ind; + case BPF_LD | BPF_B | BPF_IND: + /* A <- P[X + k:1] */ + sk_load_func = sk_load_byte; +load_ind: + ctx->flags |= SEEN_OFF | SEEN_X; + emit_addiu(r_off, r_X, k, ctx); + goto load_common; + case BPF_LDX | BPF_IMM: + /* X <- k */ + ctx->flags |= SEEN_X; + emit_load_imm(r_X, k, ctx); + break; + case BPF_LDX | BPF_MEM: + /* X <- M[k] */ + ctx->flags |= SEEN_X | SEEN_MEM; + emit_load(r_X, r_M, SCRATCH_OFF(k), ctx); + break; + case BPF_LDX | BPF_W | BPF_LEN: + /* X <- len */ + ctx->flags |= SEEN_X | SEEN_SKB; + off = offsetof(struct sk_buff, len); + emit_load(r_X, r_skb, off, ctx); + break; + case BPF_LDX | BPF_B | BPF_MSH: + /* X <- 4 * (P[k:1] & 0xf) */ + ctx->flags |= SEEN_X | SEEN_CALL | SEEN_SKB; + /* Load offset to a1 */ + emit_load_func(r_s0, (ptr)sk_load_byte, ctx); + /* + * This may emit two instructions so it may not fit + * in the delay slot. So use a0 in the delay slot. + */ + emit_load_imm(MIPS_R_A1, k, ctx); + emit_jalr(MIPS_R_RA, r_s0, ctx); + emit_reg_move(MIPS_R_A0, r_skb, ctx); /* delay slot */ + /* Check the error value */ + emit_bcond(MIPS_COND_NE, r_ret, 0, + b_imm(prog->len, ctx), ctx); + emit_reg_move(r_ret, r_zero, ctx); + /* We are good */ + /* X <- P[1:K] & 0xf */ + emit_andi(r_X, r_A, 0xf, ctx); + /* X << 2 */ + emit_b(b_imm(i + 1, ctx), ctx); + emit_sll(r_X, r_X, 2, ctx); /* delay slot */ + break; + case BPF_ST: + /* M[k] <- A */ + ctx->flags |= SEEN_MEM | SEEN_A; + emit_store(r_A, r_M, SCRATCH_OFF(k), ctx); + break; + case BPF_STX: + /* M[k] <- X */ + ctx->flags |= SEEN_MEM | SEEN_X; + emit_store(r_X, r_M, SCRATCH_OFF(k), ctx); + break; + case BPF_ALU | BPF_ADD | BPF_K: + /* A += K */ + ctx->flags |= SEEN_A; + emit_addiu(r_A, r_A, k, ctx); + break; + case BPF_ALU | BPF_ADD | BPF_X: + /* A += X */ + ctx->flags |= SEEN_A | SEEN_X; + emit_addu(r_A, r_A, r_X, ctx); + break; + case BPF_ALU | BPF_SUB | BPF_K: + /* A -= K */ + ctx->flags |= SEEN_A; + emit_addiu(r_A, r_A, -k, ctx); + break; + case BPF_ALU | BPF_SUB | BPF_X: + /* A -= X */ + ctx->flags |= SEEN_A | SEEN_X; + emit_subu(r_A, r_A, r_X, ctx); + break; + case BPF_ALU | BPF_MUL | BPF_K: + /* A *= K */ + /* Load K to scratch register before MUL */ + ctx->flags |= SEEN_A; + emit_load_imm(r_s0, k, ctx); + emit_mul(r_A, r_A, r_s0, ctx); + break; + case BPF_ALU | BPF_MUL | BPF_X: + /* A *= X */ + ctx->flags |= SEEN_A | SEEN_X; + emit_mul(r_A, r_A, r_X, ctx); + break; + case BPF_ALU | BPF_DIV | BPF_K: + /* A /= k */ + if (k == 1) + break; + if (optimize_div(&k)) { + ctx->flags |= SEEN_A; + emit_srl(r_A, r_A, k, ctx); + break; + } + ctx->flags |= SEEN_A; + emit_load_imm(r_s0, k, ctx); + emit_div(r_A, r_s0, ctx); + break; + case BPF_ALU | BPF_MOD | BPF_K: + /* A %= k */ + if (k == 1) { + ctx->flags |= SEEN_A; + emit_jit_reg_move(r_A, r_zero, ctx); + } else { + ctx->flags |= SEEN_A; + emit_load_imm(r_s0, k, ctx); + emit_mod(r_A, r_s0, ctx); + } + break; + case BPF_ALU | BPF_DIV | BPF_X: + /* A /= X */ + ctx->flags |= SEEN_X | SEEN_A; + /* Check if r_X is zero */ + emit_bcond(MIPS_COND_EQ, r_X, r_zero, + b_imm(prog->len, ctx), ctx); + emit_load_imm(r_ret, 0, ctx); /* delay slot */ + emit_div(r_A, r_X, ctx); + break; + case BPF_ALU | BPF_MOD | BPF_X: + /* A %= X */ + ctx->flags |= SEEN_X | SEEN_A; + /* Check if r_X is zero */ + emit_bcond(MIPS_COND_EQ, r_X, r_zero, + b_imm(prog->len, ctx), ctx); + emit_load_imm(r_ret, 0, ctx); /* delay slot */ + emit_mod(r_A, r_X, ctx); + break; + case BPF_ALU | BPF_OR | BPF_K: + /* A |= K */ + ctx->flags |= SEEN_A; + emit_ori(r_A, r_A, k, ctx); + break; + case BPF_ALU | BPF_OR | BPF_X: + /* A |= X */ + ctx->flags |= SEEN_A; + emit_ori(r_A, r_A, r_X, ctx); + break; + case BPF_ALU | BPF_XOR | BPF_K: + /* A ^= k */ + ctx->flags |= SEEN_A; + emit_xori(r_A, r_A, k, ctx); + break; + case BPF_ANC | SKF_AD_ALU_XOR_X: + case BPF_ALU | BPF_XOR | BPF_X: + /* A ^= X */ + ctx->flags |= SEEN_A; + emit_xor(r_A, r_A, r_X, ctx); + break; + case BPF_ALU | BPF_AND | BPF_K: + /* A &= K */ + ctx->flags |= SEEN_A; + emit_andi(r_A, r_A, k, ctx); + break; + case BPF_ALU | BPF_AND | BPF_X: + /* A &= X */ + ctx->flags |= SEEN_A | SEEN_X; + emit_and(r_A, r_A, r_X, ctx); + break; + case BPF_ALU | BPF_LSH | BPF_K: + /* A <<= K */ + ctx->flags |= SEEN_A; + emit_sll(r_A, r_A, k, ctx); + break; + case BPF_ALU | BPF_LSH | BPF_X: + /* A <<= X */ + ctx->flags |= SEEN_A | SEEN_X; + emit_sllv(r_A, r_A, r_X, ctx); + break; + case BPF_ALU | BPF_RSH | BPF_K: + /* A >>= K */ + ctx->flags |= SEEN_A; + emit_srl(r_A, r_A, k, ctx); + break; + case BPF_ALU | BPF_RSH | BPF_X: + ctx->flags |= SEEN_A | SEEN_X; + emit_srlv(r_A, r_A, r_X, ctx); + break; + case BPF_ALU | BPF_NEG: + /* A = -A */ + ctx->flags |= SEEN_A; + emit_neg(r_A, ctx); + break; + case BPF_JMP | BPF_JA: + /* pc += K */ + emit_b(b_imm(i + k + 1, ctx), ctx); + emit_nop(ctx); + break; + case BPF_JMP | BPF_JEQ | BPF_K: + /* pc += ( A == K ) ? pc->jt : pc->jf */ + condt = MIPS_COND_EQ | MIPS_COND_K; + goto jmp_cmp; + case BPF_JMP | BPF_JEQ | BPF_X: + ctx->flags |= SEEN_X; + /* pc += ( A == X ) ? pc->jt : pc->jf */ + condt = MIPS_COND_EQ | MIPS_COND_X; + goto jmp_cmp; + case BPF_JMP | BPF_JGE | BPF_K: + /* pc += ( A >= K ) ? pc->jt : pc->jf */ + condt = MIPS_COND_GE | MIPS_COND_K; + goto jmp_cmp; + case BPF_JMP | BPF_JGE | BPF_X: + ctx->flags |= SEEN_X; + /* pc += ( A >= X ) ? pc->jt : pc->jf */ + condt = MIPS_COND_GE | MIPS_COND_X; + goto jmp_cmp; + case BPF_JMP | BPF_JGT | BPF_K: + /* pc += ( A > K ) ? pc->jt : pc->jf */ + condt = MIPS_COND_GT | MIPS_COND_K; + goto jmp_cmp; + case BPF_JMP | BPF_JGT | BPF_X: + ctx->flags |= SEEN_X; + /* pc += ( A > X ) ? pc->jt : pc->jf */ + condt = MIPS_COND_GT | MIPS_COND_X; +jmp_cmp: + /* Greater or Equal */ + if ((condt & MIPS_COND_GE) || + (condt & MIPS_COND_GT)) { + if (condt & MIPS_COND_K) { /* K */ + ctx->flags |= SEEN_A; + emit_sltiu(r_s0, r_A, k, ctx); + } else { /* X */ + ctx->flags |= SEEN_A | + SEEN_X; + emit_sltu(r_s0, r_A, r_X, ctx); + } + /* A < (K|X) ? r_scrach = 1 */ + b_off = b_imm(i + inst->jf + 1, ctx); + emit_bcond(MIPS_COND_NE, r_s0, r_zero, b_off, + ctx); + emit_nop(ctx); + /* A > (K|X) ? scratch = 0 */ + if (condt & MIPS_COND_GT) { + /* Checking for equality */ + ctx->flags |= SEEN_A | SEEN_X; + if (condt & MIPS_COND_K) + emit_load_imm(r_s0, k, ctx); + else + emit_jit_reg_move(r_s0, r_X, + ctx); + b_off = b_imm(i + inst->jf + 1, ctx); + emit_bcond(MIPS_COND_EQ, r_A, r_s0, + b_off, ctx); + emit_nop(ctx); + /* Finally, A > K|X */ + b_off = b_imm(i + inst->jt + 1, ctx); + emit_b(b_off, ctx); + emit_nop(ctx); + } else { + /* A >= (K|X) so jump */ + b_off = b_imm(i + inst->jt + 1, ctx); + emit_b(b_off, ctx); + emit_nop(ctx); + } + } else { + /* A == K|X */ + if (condt & MIPS_COND_K) { /* K */ + ctx->flags |= SEEN_A; + emit_load_imm(r_s0, k, ctx); + /* jump true */ + b_off = b_imm(i + inst->jt + 1, ctx); + emit_bcond(MIPS_COND_EQ, r_A, r_s0, + b_off, ctx); + emit_nop(ctx); + /* jump false */ + b_off = b_imm(i + inst->jf + 1, + ctx); + emit_bcond(MIPS_COND_NE, r_A, r_s0, + b_off, ctx); + emit_nop(ctx); + } else { /* X */ + /* jump true */ + ctx->flags |= SEEN_A | SEEN_X; + b_off = b_imm(i + inst->jt + 1, + ctx); + emit_bcond(MIPS_COND_EQ, r_A, r_X, + b_off, ctx); + emit_nop(ctx); + /* jump false */ + b_off = b_imm(i + inst->jf + 1, ctx); + emit_bcond(MIPS_COND_NE, r_A, r_X, + b_off, ctx); + emit_nop(ctx); + } + } + break; + case BPF_JMP | BPF_JSET | BPF_K: + ctx->flags |= SEEN_A; + /* pc += (A & K) ? pc -> jt : pc -> jf */ + emit_load_imm(r_s1, k, ctx); + emit_and(r_s0, r_A, r_s1, ctx); + /* jump true */ + b_off = b_imm(i + inst->jt + 1, ctx); + emit_bcond(MIPS_COND_NE, r_s0, r_zero, b_off, ctx); + emit_nop(ctx); + /* jump false */ + b_off = b_imm(i + inst->jf + 1, ctx); + emit_b(b_off, ctx); + emit_nop(ctx); + break; + case BPF_JMP | BPF_JSET | BPF_X: + ctx->flags |= SEEN_X | SEEN_A; + /* pc += (A & X) ? pc -> jt : pc -> jf */ + emit_and(r_s0, r_A, r_X, ctx); + /* jump true */ + b_off = b_imm(i + inst->jt + 1, ctx); + emit_bcond(MIPS_COND_NE, r_s0, r_zero, b_off, ctx); + emit_nop(ctx); + /* jump false */ + b_off = b_imm(i + inst->jf + 1, ctx); + emit_b(b_off, ctx); + emit_nop(ctx); + break; + case BPF_RET | BPF_A: + ctx->flags |= SEEN_A; + if (i != prog->len - 1) + /* + * If this is not the last instruction + * then jump to the epilogue + */ + emit_b(b_imm(prog->len, ctx), ctx); + emit_reg_move(r_ret, r_A, ctx); /* delay slot */ + break; + case BPF_RET | BPF_K: + /* + * It can emit two instructions so it does not fit on + * the delay slot. + */ + emit_load_imm(r_ret, k, ctx); + if (i != prog->len - 1) { + /* + * If this is not the last instruction + * then jump to the epilogue + */ + emit_b(b_imm(prog->len, ctx), ctx); + emit_nop(ctx); + } + break; + case BPF_MISC | BPF_TAX: + /* X = A */ + ctx->flags |= SEEN_X | SEEN_A; + emit_jit_reg_move(r_X, r_A, ctx); + break; + case BPF_MISC | BPF_TXA: + /* A = X */ + ctx->flags |= SEEN_A | SEEN_X; + emit_jit_reg_move(r_A, r_X, ctx); + break; + /* AUX */ + case BPF_ANC | SKF_AD_PROTOCOL: + /* A = ntohs(skb->protocol */ + ctx->flags |= SEEN_SKB | SEEN_OFF | SEEN_A; + BUILD_BUG_ON(sizeof_field(struct sk_buff, + protocol) != 2); + off = offsetof(struct sk_buff, protocol); + emit_half_load(r_A, r_skb, off, ctx); +#ifdef CONFIG_CPU_LITTLE_ENDIAN + /* This needs little endian fixup */ + if (cpu_has_wsbh) { + /* R2 and later have the wsbh instruction */ + emit_wsbh(r_A, r_A, ctx); + } else { + /* Get first byte */ + emit_andi(r_tmp_imm, r_A, 0xff, ctx); + /* Shift it */ + emit_sll(r_tmp, r_tmp_imm, 8, ctx); + /* Get second byte */ + emit_srl(r_tmp_imm, r_A, 8, ctx); + emit_andi(r_tmp_imm, r_tmp_imm, 0xff, ctx); + /* Put everyting together in r_A */ + emit_or(r_A, r_tmp, r_tmp_imm, ctx); + } +#endif + break; + case BPF_ANC | SKF_AD_CPU: + ctx->flags |= SEEN_A | SEEN_OFF; + /* A = current_thread_info()->cpu */ + BUILD_BUG_ON(sizeof_field(struct thread_info, + cpu) != 4); + off = offsetof(struct thread_info, cpu); + /* $28/gp points to the thread_info struct */ + emit_load(r_A, 28, off, ctx); + break; + case BPF_ANC | SKF_AD_IFINDEX: + /* A = skb->dev->ifindex */ + case BPF_ANC | SKF_AD_HATYPE: + /* A = skb->dev->type */ + ctx->flags |= SEEN_SKB | SEEN_A; + off = offsetof(struct sk_buff, dev); + /* Load *dev pointer */ + emit_load_ptr(r_s0, r_skb, off, ctx); + /* error (0) in the delay slot */ + emit_bcond(MIPS_COND_EQ, r_s0, r_zero, + b_imm(prog->len, ctx), ctx); + emit_reg_move(r_ret, r_zero, ctx); + if (code == (BPF_ANC | SKF_AD_IFINDEX)) { + BUILD_BUG_ON(sizeof_field(struct net_device, ifindex) != 4); + off = offsetof(struct net_device, ifindex); + emit_load(r_A, r_s0, off, ctx); + } else { /* (code == (BPF_ANC | SKF_AD_HATYPE) */ + BUILD_BUG_ON(sizeof_field(struct net_device, type) != 2); + off = offsetof(struct net_device, type); + emit_half_load_unsigned(r_A, r_s0, off, ctx); + } + break; + case BPF_ANC | SKF_AD_MARK: + ctx->flags |= SEEN_SKB | SEEN_A; + BUILD_BUG_ON(sizeof_field(struct sk_buff, mark) != 4); + off = offsetof(struct sk_buff, mark); + emit_load(r_A, r_skb, off, ctx); + break; + case BPF_ANC | SKF_AD_RXHASH: + ctx->flags |= SEEN_SKB | SEEN_A; + BUILD_BUG_ON(sizeof_field(struct sk_buff, hash) != 4); + off = offsetof(struct sk_buff, hash); + emit_load(r_A, r_skb, off, ctx); + break; + case BPF_ANC | SKF_AD_VLAN_TAG: + ctx->flags |= SEEN_SKB | SEEN_A; + BUILD_BUG_ON(sizeof_field(struct sk_buff, + vlan_tci) != 2); + off = offsetof(struct sk_buff, vlan_tci); + emit_half_load_unsigned(r_A, r_skb, off, ctx); + break; + case BPF_ANC | SKF_AD_VLAN_TAG_PRESENT: + ctx->flags |= SEEN_SKB | SEEN_A; + emit_load_byte(r_A, r_skb, PKT_VLAN_PRESENT_OFFSET(), ctx); + if (PKT_VLAN_PRESENT_BIT) + emit_srl(r_A, r_A, PKT_VLAN_PRESENT_BIT, ctx); + if (PKT_VLAN_PRESENT_BIT < 7) + emit_andi(r_A, r_A, 1, ctx); + break; + case BPF_ANC | SKF_AD_PKTTYPE: + ctx->flags |= SEEN_SKB; + + emit_load_byte(r_tmp, r_skb, PKT_TYPE_OFFSET(), ctx); + /* Keep only the last 3 bits */ + emit_andi(r_A, r_tmp, PKT_TYPE_MAX, ctx); +#ifdef __BIG_ENDIAN_BITFIELD + /* Get the actual packet type to the lower 3 bits */ + emit_srl(r_A, r_A, 5, ctx); +#endif + break; + case BPF_ANC | SKF_AD_QUEUE: + ctx->flags |= SEEN_SKB | SEEN_A; + BUILD_BUG_ON(sizeof_field(struct sk_buff, + queue_mapping) != 2); + BUILD_BUG_ON(offsetof(struct sk_buff, + queue_mapping) > 0xff); + off = offsetof(struct sk_buff, queue_mapping); + emit_half_load_unsigned(r_A, r_skb, off, ctx); + break; + default: + pr_debug("%s: Unhandled opcode: 0x%02x\n", __FILE__, + inst->code); + 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 bpf_prog *fp) +{ + struct jit_ctx ctx; + unsigned int alloc_size, tmp_idx; + + if (!bpf_jit_enable) + return; + + memset(&ctx, 0, sizeof(ctx)); + + ctx.offsets = kcalloc(fp->len + 1, sizeof(*ctx.offsets), GFP_KERNEL); + if (ctx.offsets == NULL) + return; + + ctx.skf = fp; + + if (build_body(&ctx)) + goto out; + + tmp_idx = ctx.idx; + build_prologue(&ctx); + ctx.prologue_bytes = (ctx.idx - tmp_idx) * 4; + /* just to complete the ctx.idx count */ + build_epilogue(&ctx); + + alloc_size = 4 * ctx.idx; + ctx.target = module_alloc(alloc_size); + if (ctx.target == NULL) + goto out; + + /* Clean it */ + memset(ctx.target, 0, alloc_size); + + ctx.idx = 0; + + /* Generate the actual JIT code */ + build_prologue(&ctx); + build_body(&ctx); + build_epilogue(&ctx); + + /* Update the icache */ + flush_icache_range((ptr)ctx.target, (ptr)(ctx.target + ctx.idx)); + + if (bpf_jit_enable > 1) + /* Dump JIT code */ + bpf_jit_dump(fp->len, alloc_size, 2, ctx.target); + + fp->bpf_func = (void *)ctx.target; + fp->jited = 1; + +out: + kfree(ctx.offsets); +} + +void bpf_jit_free(struct bpf_prog *fp) +{ + if (fp->jited) + module_memfree(fp->bpf_func); + + bpf_prog_unlock_free(fp); +} |