1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Common functionality for RV32 and RV64 BPF JIT compilers 4 * 5 * Copyright (c) 2019 Björn Töpel <bjorn.topel@gmail.com> 6 * 7 */ 8 9 #include <linux/bpf.h> 10 #include <linux/filter.h> 11 #include "bpf_jit.h" 12 13 /* Number of iterations to try until offsets converge. */ 14 #define NR_JIT_ITERATIONS 16 15 16 static int build_body(struct rv_jit_context *ctx, bool extra_pass, int *offset) 17 { 18 const struct bpf_prog *prog = ctx->prog; 19 int i; 20 21 for (i = 0; i < prog->len; i++) { 22 const struct bpf_insn *insn = &prog->insnsi[i]; 23 int ret; 24 25 ret = bpf_jit_emit_insn(insn, ctx, extra_pass); 26 /* BPF_LD | BPF_IMM | BPF_DW: skip the next instruction. */ 27 if (ret > 0) 28 i++; 29 if (offset) 30 offset[i] = ctx->ninsns; 31 if (ret < 0) 32 return ret; 33 } 34 return 0; 35 } 36 37 bool bpf_jit_needs_zext(void) 38 { 39 return true; 40 } 41 42 struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) 43 { 44 bool tmp_blinded = false, extra_pass = false; 45 struct bpf_prog *tmp, *orig_prog = prog; 46 int pass = 0, prev_ninsns = 0, i; 47 struct rv_jit_data *jit_data; 48 struct rv_jit_context *ctx; 49 unsigned int image_size = 0; 50 51 if (!prog->jit_requested) 52 return orig_prog; 53 54 tmp = bpf_jit_blind_constants(prog); 55 if (IS_ERR(tmp)) 56 return orig_prog; 57 if (tmp != prog) { 58 tmp_blinded = true; 59 prog = tmp; 60 } 61 62 jit_data = prog->aux->jit_data; 63 if (!jit_data) { 64 jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL); 65 if (!jit_data) { 66 prog = orig_prog; 67 goto out; 68 } 69 prog->aux->jit_data = jit_data; 70 } 71 72 ctx = &jit_data->ctx; 73 74 if (ctx->offset) { 75 extra_pass = true; 76 image_size = sizeof(u32) * ctx->ninsns; 77 goto skip_init_ctx; 78 } 79 80 ctx->prog = prog; 81 ctx->offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL); 82 if (!ctx->offset) { 83 prog = orig_prog; 84 goto out_offset; 85 } 86 for (i = 0; i < prog->len; i++) { 87 prev_ninsns += 32; 88 ctx->offset[i] = prev_ninsns; 89 } 90 91 for (i = 0; i < NR_JIT_ITERATIONS; i++) { 92 pass++; 93 ctx->ninsns = 0; 94 if (build_body(ctx, extra_pass, ctx->offset)) { 95 prog = orig_prog; 96 goto out_offset; 97 } 98 bpf_jit_build_prologue(ctx); 99 ctx->epilogue_offset = ctx->ninsns; 100 bpf_jit_build_epilogue(ctx); 101 102 if (ctx->ninsns == prev_ninsns) { 103 if (jit_data->header) 104 break; 105 106 image_size = sizeof(u32) * ctx->ninsns; 107 jit_data->header = 108 bpf_jit_binary_alloc(image_size, 109 &jit_data->image, 110 sizeof(u32), 111 bpf_fill_ill_insns); 112 if (!jit_data->header) { 113 prog = orig_prog; 114 goto out_offset; 115 } 116 117 ctx->insns = (u32 *)jit_data->image; 118 /* 119 * Now, when the image is allocated, the image can 120 * potentially shrink more (auipc/jalr -> jal). 121 */ 122 } 123 prev_ninsns = ctx->ninsns; 124 } 125 126 if (i == NR_JIT_ITERATIONS) { 127 pr_err("bpf-jit: image did not converge in <%d passes!\n", i); 128 bpf_jit_binary_free(jit_data->header); 129 prog = orig_prog; 130 goto out_offset; 131 } 132 133 skip_init_ctx: 134 pass++; 135 ctx->ninsns = 0; 136 137 bpf_jit_build_prologue(ctx); 138 if (build_body(ctx, extra_pass, NULL)) { 139 bpf_jit_binary_free(jit_data->header); 140 prog = orig_prog; 141 goto out_offset; 142 } 143 bpf_jit_build_epilogue(ctx); 144 145 if (bpf_jit_enable > 1) 146 bpf_jit_dump(prog->len, image_size, pass, ctx->insns); 147 148 prog->bpf_func = (void *)ctx->insns; 149 prog->jited = 1; 150 prog->jited_len = image_size; 151 152 bpf_flush_icache(jit_data->header, ctx->insns + ctx->ninsns); 153 154 if (!prog->is_func || extra_pass) { 155 out_offset: 156 kfree(ctx->offset); 157 kfree(jit_data); 158 prog->aux->jit_data = NULL; 159 } 160 out: 161 162 if (tmp_blinded) 163 bpf_jit_prog_release_other(prog, prog == orig_prog ? 164 tmp : orig_prog); 165 return prog; 166 } 167