diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index cdc79de0c794..945e5f690ede 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -141,14 +141,17 @@ static inline void emit_addr_mov_i64(const int reg, const u64 val, } } -static inline int bpf2a64_offset(int bpf_to, int bpf_from, +static inline int bpf2a64_offset(int bpf_insn, int off, const struct jit_ctx *ctx) { - int to = ctx->offset[bpf_to]; - /* -1 to account for the Branch instruction */ - int from = ctx->offset[bpf_from] - 1; - - return to - from; + /* BPF JMP offset is relative to the next instruction */ + bpf_insn++; + /* + * Whereas arm64 branch instructions encode the offset + * from the branch itself, so we must subtract 1 from the + * instruction offset. + */ + return ctx->offset[bpf_insn + off] - (ctx->offset[bpf_insn] - 1); } static void jit_fill_hole(void *area, unsigned int size) @@ -532,7 +535,7 @@ emit_bswap_uxt: /* JUMP off */ case BPF_JMP | BPF_JA: - jmp_offset = bpf2a64_offset(i + off, i, ctx); + jmp_offset = bpf2a64_offset(i, off, ctx); check_imm26(jmp_offset); emit(A64_B(jmp_offset), ctx); break; @@ -559,7 +562,7 @@ emit_bswap_uxt: case BPF_JMP32 | BPF_JSLE | BPF_X: emit(A64_CMP(is64, dst, src), ctx); emit_cond_jmp: - jmp_offset = bpf2a64_offset(i + off, i, ctx); + jmp_offset = bpf2a64_offset(i, off, ctx); check_imm19(jmp_offset); switch (BPF_OP(code)) { case BPF_JEQ: @@ -780,10 +783,21 @@ static int build_body(struct jit_ctx *ctx, bool extra_pass) const struct bpf_prog *prog = ctx->prog; int i; + /* + * - offset[0] offset of the end of prologue, + * start of the 1st instruction. + * - offset[1] - offset of the end of 1st instruction, + * start of the 2nd instruction + * [....] + * - offset[3] - offset of the end of 3rd instruction, + * start of 4th instruction + */ for (i = 0; i < prog->len; i++) { const struct bpf_insn *insn = &prog->insnsi[i]; int ret; + if (ctx->image == NULL) + ctx->offset[i] = ctx->idx; ret = build_insn(insn, ctx, extra_pass); if (ret > 0) { i++; @@ -791,11 +805,16 @@ static int build_body(struct jit_ctx *ctx, bool extra_pass) ctx->offset[i] = ctx->idx; continue; } - if (ctx->image == NULL) - ctx->offset[i] = ctx->idx; if (ret) return ret; } + /* + * offset is allocated with prog->len + 1 so fill in + * the last element with the offset after the last + * instruction (end of program) + */ + if (ctx->image == NULL) + ctx->offset[i] = ctx->idx; return 0; } @@ -871,7 +890,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) memset(&ctx, 0, sizeof(ctx)); ctx.prog = prog; - ctx.offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL); + ctx.offset = kcalloc(prog->len + 1, sizeof(int), GFP_KERNEL); if (ctx.offset == NULL) { prog = orig_prog; goto out_off; @@ -951,7 +970,7 @@ skip_init_ctx: prog->jited_len = image_size; if (!prog->is_func || extra_pass) { - bpf_prog_fill_jited_linfo(prog, ctx.offset); + bpf_prog_fill_jited_linfo(prog, ctx.offset + 1); out_off: kfree(ctx.offset); kfree(jit_data);