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-rw-r--r--arch/mips/net/bpf_jit.c1431
1 files changed, 1431 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..b87390a56a2f
--- /dev/null
+++ b/arch/mips/net/bpf_jit.c
@@ -0,0 +1,1431 @@
+/*
+ * 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/kconfig.h>
+#include <linux/moduleloader.h>
+#include <linux/netdevice.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <asm/bitops.h>
+#include <asm/cacheflush.h>
+#include <asm/cpu-features.h>
+#include <asm/uasm.h>
+
+#include "bpf_jit.h"
+
+/* ABI
+ *
+ * s0 1st scratch register
+ * s1 2nd scratch register
+ * s2 offset register
+ * s3 BPF register A
+ * s4 BPF register X
+ * s5 *skb
+ * s6 *scratch memory
+ *
+ * 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 RSIZE (sizeof(unsigned long))
+#define ptr typeof(unsigned long)
+
+/* ABI specific return values */
+#ifdef CONFIG_32BIT /* O32 */
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+#define r_err MIPS_R_V1
+#define r_val MIPS_R_V0
+#else /* CONFIG_CPU_LITTLE_ENDIAN */
+#define r_err MIPS_R_V0
+#define r_val MIPS_R_V1
+#endif
+#else /* N64 */
+#define r_err MIPS_R_V0
+#define r_val MIPS_R_V0
+#endif
+
+#define r_ret MIPS_R_V0
+
+/*
+ * Use 2 scratch registers to avoid pipeline interlocks.
+ * There is no overhead during epilogue and prologue since
+ * any of the $s0-$s6 registers will only be preserved if
+ * they are going to actually be used.
+ */
+#define r_s0 MIPS_R_S0 /* scratch reg 1 */
+#define r_s1 MIPS_R_S1 /* scratch reg 2 */
+#define r_off MIPS_R_S2
+#define r_A MIPS_R_S3
+#define r_X MIPS_R_S4
+#define r_skb MIPS_R_S5
+#define r_M MIPS_R_S6
+#define r_tmp_imm MIPS_R_T6 /* No need to preserve this */
+#define r_tmp MIPS_R_T7 /* No need to preserve this */
+#define r_zero MIPS_R_ZERO
+#define r_sp MIPS_R_SP
+#define r_ra MIPS_R_RA
+
+#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_S0 SEEN_SREG(0)
+#define SEEN_S1 SEEN_SREG(1)
+#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)
+
+/* 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 sk_filter *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)
+
+/* 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_daddu(unsigned int dst, unsigned int src1,
+ unsigned int src2, struct jit_ctx *ctx)
+{
+ emit_instr(ctx, daddu, dst, src1, src2);
+}
+
+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)
+{
+ if (config_enabled(CONFIG_64BIT))
+ emit_instr(ctx, daddiu, r_sp, r_sp, offset);
+ else
+ emit_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)
+{
+ if (config_enabled(CONFIG_64BIT))
+ emit_instr(ctx, sd, reg, offset, base);
+ else
+ emit_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)
+{
+ if (config_enabled(CONFIG_64BIT))
+ emit_instr(ctx, ld, reg, offset, base);
+ else
+ emit_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_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_mflo(&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 */
+ if (config_enabled(CONFIG_64BIT))
+ emit_instr(ctx, ld, dst, imm, src);
+ else
+ emit_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 (config_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)
+{
+ if (config_enabled(CONFIG_64BIT))
+ emit_daddu(dst, src, r_zero, ctx);
+ else
+ emit_addu(dst, src, r_zero, ctx);
+}
+
+/* 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 = config_enabled(CONFIG_64BIT) ? 16 : 8;
+ num = (num + (align - 1)) & -align;
+ return num;
+}
+
+static bool is_load_to_a(u16 inst)
+{
+ switch (inst) {
+ case BPF_LD | BPF_W | BPF_LEN:
+ case BPF_LD | BPF_W | BPF_ABS:
+ case BPF_LD | BPF_H | BPF_ABS:
+ case BPF_LD | BPF_B | BPF_ABS:
+ return true;
+ default:
+ return false;
+ }
+}
+
+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 */
+ emit_stack_offset(-align_sp(offset), ctx);
+
+ if (ctx->flags & SEEN_CALL) {
+ /* Argument save area */
+ if (config_enabled(CONFIG_64BIT))
+ /* Bottom of current frame */
+ real_off = align_sp(offset) - RSIZE;
+ else
+ /* Top of previous frame */
+ real_off = align_sp(offset) + RSIZE;
+ emit_store_stack_reg(MIPS_R_A0, r_sp, real_off, ctx);
+ emit_store_stack_reg(MIPS_R_A1, r_sp, real_off + RSIZE, ctx);
+
+ real_off = 0;
+ }
+
+ 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 += RSIZE;
+ }
+ 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 += RSIZE;
+ }
+
+ /* Setup r_M leaving the alignment gap if necessary */
+ if (ctx->flags & SEEN_MEM) {
+ if (real_off % (RSIZE * 2))
+ real_off += RSIZE;
+ if (config_enabled(CONFIG_64BIT))
+ emit_daddiu(r_M, r_sp, real_off, ctx);
+ else
+ emit_addiu(r_M, r_sp, real_off, ctx);
+ }
+}
+
+static void restore_bpf_jit_regs(struct jit_ctx *ctx,
+ unsigned int offset)
+{
+ int i, real_off = 0;
+ u32 sflags, tmp_flags;
+
+ if (ctx->flags & SEEN_CALL) {
+ if (config_enabled(CONFIG_64BIT))
+ /* Bottom of current frame */
+ real_off = align_sp(offset) - RSIZE;
+ else
+ /* Top of previous frame */
+ real_off = align_sp(offset) + RSIZE;
+ emit_load_stack_reg(MIPS_R_A0, r_sp, real_off, ctx);
+ emit_load_stack_reg(MIPS_R_A1, r_sp, real_off + RSIZE, ctx);
+
+ real_off = 0;
+ }
+
+ 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 += RSIZE;
+ }
+ 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 */
+ 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) * RSIZE;
+
+ if (ctx->flags & SEEN_MEM)
+ sp_off += 4 * BPF_MEMWORDS; /* BPF_MEMWORDS are 32-bit */
+
+ if (ctx->flags & SEEN_CALL)
+ /*
+ * The JIT code make calls to external functions using 2
+ * arguments. Therefore, for o32 we don't need to allocate
+ * space because we don't care if the argumetns are lost
+ * across calls. We do need however to preserve incoming
+ * arguments but the space is already allocated for us by
+ * the caller. On the other hand, for n64, we need to allocate
+ * this space ourselves. We need to preserve $ra as well.
+ */
+ sp_off += config_enabled(CONFIG_64BIT) ?
+ (ARGS_USED_BY_JIT + 1) * RSIZE : RSIZE;
+
+ /*
+ * Subtract the bytes for the last registers since we only care about
+ * the location on the stack pointer.
+ */
+ return sp_off - RSIZE;
+}
+
+static void build_prologue(struct jit_ctx *ctx)
+{
+ u16 first_inst = ctx->skf->insns[0].code;
+ 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_X)
+ emit_jit_reg_move(r_X, r_zero, ctx);
+
+ /* Do not leak kernel data to userspace */
+ if ((first_inst != (BPF_RET | BPF_K)) && !(is_load_to_a(first_inst)))
+ 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);
+}
+
+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);
+}
+
+#ifdef __BIG_ENDIAN_BITFIELD
+#define PKT_TYPE_MAX (7 << 5)
+#else
+#define PKT_TYPE_MAX 7
+#endif
+static int pkt_type_offset(void)
+{
+ struct sk_buff skb_probe = {
+ .pkt_type = ~0,
+ };
+ u8 *ct = (u8 *)&skb_probe;
+ unsigned int off;
+
+ for (off = 0; off < sizeof(struct sk_buff); off++) {
+ if (ct[off] == PKT_TYPE_MAX)
+ return off;
+ }
+ pr_err_once("Please fix pkt_type_offset(), as pkt_type couldn't be found\n");
+ return -1;
+}
+
+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 int i, off, load_order, condt;
+ u32 k, b_off __maybe_unused;
+
+ 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(FIELD_SIZEOF(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] */
+ load_order = 2;
+ goto load;
+ case BPF_LD | BPF_H | BPF_ABS:
+ /* A <- P[k:2] */
+ load_order = 1;
+ goto load;
+ case BPF_LD | BPF_B | BPF_ABS:
+ /* A <- P[k:1] */
+ load_order = 0;
+load:
+ /* the interpreter will deal with the negative K */
+ if ((int)k < 0)
+ return -ENOTSUPP;
+
+ emit_load_imm(r_off, k, ctx);
+load_common:
+ /*
+ * We may got here from the indirect loads so
+ * return if offset is negative.
+ */
+ emit_slt(r_s0, r_off, r_zero, ctx);
+ emit_bcond(MIPS_COND_NE, r_s0, r_zero,
+ b_imm(prog->len, ctx), ctx);
+ emit_reg_move(r_ret, r_zero, ctx);
+
+ ctx->flags |= SEEN_CALL | SEEN_OFF | SEEN_S0 |
+ SEEN_SKB | SEEN_A;
+
+ emit_load_func(r_s0, (ptr)load_func[load_order],
+ 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 */
+ if (config_enabled(CONFIG_64BIT)) {
+ /* Get error code from the top 32-bits */
+ emit_dsrl32(r_s0, r_val, 0, ctx);
+ /* Branch to 3 instructions ahead */
+ emit_bcond(MIPS_COND_NE, r_s0, r_zero, 3 << 2,
+ ctx);
+ } else {
+ /* Branch to 3 instructions ahead */
+ emit_bcond(MIPS_COND_NE, r_err, r_zero, 3 << 2,
+ ctx);
+ }
+ emit_nop(ctx);
+ /* We are good */
+ emit_b(b_imm(i + 1, ctx), ctx);
+ emit_jit_reg_move(r_A, r_val, ctx);
+ /* Return with error */
+ emit_b(b_imm(prog->len, ctx), ctx);
+ emit_reg_move(r_ret, r_zero, ctx);
+ break;
+ case BPF_LD | BPF_W | BPF_IND:
+ /* A <- P[X + k:4] */
+ load_order = 2;
+ goto load_ind;
+ case BPF_LD | BPF_H | BPF_IND:
+ /* A <- P[X + k:2] */
+ load_order = 1;
+ goto load_ind;
+ case BPF_LD | BPF_B | BPF_IND:
+ /* A <- P[X + k:1] */
+ load_order = 0;
+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:
+ /* the interpreter will deal with the negative K */
+ if ((int)k < 0)
+ return -ENOTSUPP;
+
+ /* X <- 4 * (P[k:1] & 0xf) */
+ ctx->flags |= SEEN_X | SEEN_CALL | SEEN_S0 | SEEN_SKB;
+ /* Load offset to a1 */
+ emit_load_func(r_s0, (ptr)jit_get_skb_b, 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 */
+ if (config_enabled(CONFIG_64BIT)) {
+ /* Top 32-bits of $v0 on 64-bit */
+ emit_dsrl32(r_s0, r_val, 0, ctx);
+ emit_bcond(MIPS_COND_NE, r_s0, r_zero,
+ 3 << 2, ctx);
+ } else {
+ emit_bcond(MIPS_COND_NE, r_err, r_zero,
+ 3 << 2, ctx);
+ }
+ /* No need for delay slot */
+ /* We are good */
+ /* X <- P[1:K] & 0xf */
+ emit_andi(r_X, r_val, 0xf, ctx);
+ /* X << 2 */
+ emit_b(b_imm(i + 1, ctx), ctx);
+ emit_sll(r_X, r_X, 2, ctx); /* delay slot */
+ /* Return with error */
+ emit_b(b_imm(prog->len, ctx), ctx);
+ emit_load_imm(r_ret, 0, 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 | SEEN_S0;
+ 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 | SEEN_S0;
+ 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 || optimize_div(&k)) {
+ ctx->flags |= SEEN_A;
+ emit_jit_reg_move(r_A, r_zero, ctx);
+ } else {
+ ctx->flags |= SEEN_A | SEEN_S0;
+ 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_val, 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_val, 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_S0 | SEEN_A;
+ emit_sltiu(r_s0, r_A, k, ctx);
+ } else { /* X */
+ ctx->flags |= SEEN_S0 | 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_S0 | 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_S0 | 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_S0 | SEEN_S1 | 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_S0 | 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(FIELD_SIZEOF(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_mips_r2) {
+ /* 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(FIELD_SIZEOF(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 */
+ ctx->flags |= SEEN_SKB | SEEN_A | SEEN_S0;
+ 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);
+ BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
+ ifindex) != 4);
+ off = offsetof(struct net_device, ifindex);
+ emit_load(r_A, r_s0, off, ctx);
+ break;
+ case BPF_ANC | SKF_AD_MARK:
+ ctx->flags |= SEEN_SKB | SEEN_A;
+ BUILD_BUG_ON(FIELD_SIZEOF(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(FIELD_SIZEOF(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:
+ case BPF_ANC | SKF_AD_VLAN_TAG_PRESENT:
+ ctx->flags |= SEEN_SKB | SEEN_S0 | SEEN_A;
+ BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
+ vlan_tci) != 2);
+ off = offsetof(struct sk_buff, vlan_tci);
+ emit_half_load(r_s0, r_skb, off, ctx);
+ if (code == (BPF_ANC | SKF_AD_VLAN_TAG)) {
+ emit_andi(r_A, r_s0, (u16)~VLAN_TAG_PRESENT, ctx);
+ } else {
+ emit_andi(r_A, r_s0, VLAN_TAG_PRESENT, ctx);
+ /* return 1 if present */
+ emit_sltu(r_A, r_zero, r_A, ctx);
+ }
+ break;
+ case BPF_ANC | SKF_AD_PKTTYPE:
+ ctx->flags |= SEEN_SKB;
+
+ off = pkt_type_offset();
+
+ if (off < 0)
+ return -1;
+ emit_load_byte(r_tmp, r_skb, off, 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(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_half_load(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;
+}
+
+int bpf_jit_enable __read_mostly;
+
+void bpf_jit_compile(struct sk_filter *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, 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 sk_filter *fp)
+{
+ if (fp->jited)
+ module_free(NULL, fp->bpf_func);
+ kfree(fp);
+}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.