167 строки
3.5 KiB
C
167 строки
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Common functionality for RV32 and RV64 BPF JIT compilers
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*
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* Copyright (c) 2019 Björn Töpel <bjorn.topel@gmail.com>
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*
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*/
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#include <linux/bpf.h>
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#include <linux/filter.h>
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#include "bpf_jit.h"
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/* Number of iterations to try until offsets converge. */
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#define NR_JIT_ITERATIONS 16
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static int build_body(struct rv_jit_context *ctx, bool extra_pass, int *offset)
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{
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const struct bpf_prog *prog = ctx->prog;
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int i;
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for (i = 0; i < prog->len; i++) {
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const struct bpf_insn *insn = &prog->insnsi[i];
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int ret;
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ret = bpf_jit_emit_insn(insn, ctx, extra_pass);
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/* BPF_LD | BPF_IMM | BPF_DW: skip the next instruction. */
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if (ret > 0)
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i++;
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if (offset)
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offset[i] = ctx->ninsns;
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if (ret < 0)
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return ret;
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}
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return 0;
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}
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bool bpf_jit_needs_zext(void)
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{
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return true;
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}
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struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
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{
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bool tmp_blinded = false, extra_pass = false;
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struct bpf_prog *tmp, *orig_prog = prog;
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int pass = 0, prev_ninsns = 0, i;
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struct rv_jit_data *jit_data;
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struct rv_jit_context *ctx;
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unsigned int image_size = 0;
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if (!prog->jit_requested)
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return orig_prog;
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tmp = bpf_jit_blind_constants(prog);
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if (IS_ERR(tmp))
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return orig_prog;
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if (tmp != prog) {
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tmp_blinded = true;
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prog = tmp;
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}
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jit_data = prog->aux->jit_data;
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if (!jit_data) {
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jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
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if (!jit_data) {
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prog = orig_prog;
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goto out;
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}
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prog->aux->jit_data = jit_data;
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}
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ctx = &jit_data->ctx;
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if (ctx->offset) {
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extra_pass = true;
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image_size = sizeof(*ctx->insns) * ctx->ninsns;
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goto skip_init_ctx;
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}
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ctx->prog = prog;
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ctx->offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL);
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if (!ctx->offset) {
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prog = orig_prog;
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goto out_offset;
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}
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for (i = 0; i < prog->len; i++) {
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prev_ninsns += 32;
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ctx->offset[i] = prev_ninsns;
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}
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for (i = 0; i < NR_JIT_ITERATIONS; i++) {
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pass++;
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ctx->ninsns = 0;
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if (build_body(ctx, extra_pass, ctx->offset)) {
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prog = orig_prog;
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goto out_offset;
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}
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bpf_jit_build_prologue(ctx);
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ctx->epilogue_offset = ctx->ninsns;
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bpf_jit_build_epilogue(ctx);
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if (ctx->ninsns == prev_ninsns) {
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if (jit_data->header)
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break;
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image_size = sizeof(*ctx->insns) * ctx->ninsns;
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jit_data->header =
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bpf_jit_binary_alloc(image_size,
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&jit_data->image,
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sizeof(u32),
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bpf_fill_ill_insns);
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if (!jit_data->header) {
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prog = orig_prog;
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goto out_offset;
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}
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ctx->insns = (u16 *)jit_data->image;
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/*
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* Now, when the image is allocated, the image can
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* potentially shrink more (auipc/jalr -> jal).
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*/
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}
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prev_ninsns = ctx->ninsns;
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}
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if (i == NR_JIT_ITERATIONS) {
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pr_err("bpf-jit: image did not converge in <%d passes!\n", i);
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bpf_jit_binary_free(jit_data->header);
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prog = orig_prog;
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goto out_offset;
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}
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skip_init_ctx:
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pass++;
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ctx->ninsns = 0;
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bpf_jit_build_prologue(ctx);
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if (build_body(ctx, extra_pass, NULL)) {
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bpf_jit_binary_free(jit_data->header);
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prog = orig_prog;
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goto out_offset;
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}
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bpf_jit_build_epilogue(ctx);
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if (bpf_jit_enable > 1)
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bpf_jit_dump(prog->len, image_size, pass, ctx->insns);
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prog->bpf_func = (void *)ctx->insns;
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prog->jited = 1;
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prog->jited_len = image_size;
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bpf_flush_icache(jit_data->header, ctx->insns + ctx->ninsns);
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if (!prog->is_func || extra_pass) {
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out_offset:
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kfree(ctx->offset);
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kfree(jit_data);
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prog->aux->jit_data = NULL;
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}
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out:
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if (tmp_blinded)
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bpf_jit_prog_release_other(prog, prog == orig_prog ?
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tmp : orig_prog);
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return prog;
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}
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