| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Common functionality for RV32 and RV64 BPF JIT compilers |
| * |
| * Copyright (c) 2019 Björn Töpel <bjorn.topel@gmail.com> |
| * |
| */ |
| |
| #include <linux/bpf.h> |
| #include <linux/filter.h> |
| #include <linux/memory.h> |
| #include <asm/patch.h> |
| #include <asm/cfi.h> |
| #include "bpf_jit.h" |
| |
| /* Number of iterations to try until offsets converge. */ |
| #define NR_JIT_ITERATIONS 32 |
| |
| static int build_body(struct rv_jit_context *ctx, bool extra_pass, int *offset) |
| { |
| const struct bpf_prog *prog = ctx->prog; |
| int i; |
| |
| for (i = 0; i < prog->len; i++) { |
| const struct bpf_insn *insn = &prog->insnsi[i]; |
| int ret; |
| |
| ret = bpf_jit_emit_insn(insn, ctx, extra_pass); |
| /* BPF_LD | BPF_IMM | BPF_DW: skip the next instruction. */ |
| if (ret > 0) |
| i++; |
| if (offset) |
| offset[i] = ctx->ninsns; |
| if (ret < 0) |
| return ret; |
| } |
| return 0; |
| } |
| |
| bool bpf_jit_needs_zext(void) |
| { |
| return true; |
| } |
| |
| struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) |
| { |
| unsigned int prog_size = 0, extable_size = 0; |
| bool tmp_blinded = false, extra_pass = false; |
| struct bpf_prog *tmp, *orig_prog = prog; |
| int pass = 0, prev_ninsns = 0, i; |
| struct rv_jit_data *jit_data; |
| struct rv_jit_context *ctx; |
| |
| if (!prog->jit_requested) |
| return orig_prog; |
| |
| tmp = bpf_jit_blind_constants(prog); |
| if (IS_ERR(tmp)) |
| return orig_prog; |
| if (tmp != prog) { |
| tmp_blinded = true; |
| prog = tmp; |
| } |
| |
| jit_data = prog->aux->jit_data; |
| if (!jit_data) { |
| jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL); |
| if (!jit_data) { |
| prog = orig_prog; |
| goto out; |
| } |
| prog->aux->jit_data = jit_data; |
| } |
| |
| ctx = &jit_data->ctx; |
| |
| if (ctx->offset) { |
| extra_pass = true; |
| prog_size = sizeof(*ctx->insns) * ctx->ninsns; |
| goto skip_init_ctx; |
| } |
| |
| ctx->arena_vm_start = bpf_arena_get_kern_vm_start(prog->aux->arena); |
| ctx->user_vm_start = bpf_arena_get_user_vm_start(prog->aux->arena); |
| ctx->prog = prog; |
| ctx->offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL); |
| if (!ctx->offset) { |
| prog = orig_prog; |
| goto out_offset; |
| } |
| |
| if (build_body(ctx, extra_pass, NULL)) { |
| prog = orig_prog; |
| goto out_offset; |
| } |
| |
| for (i = 0; i < prog->len; i++) { |
| prev_ninsns += 32; |
| ctx->offset[i] = prev_ninsns; |
| } |
| |
| for (i = 0; i < NR_JIT_ITERATIONS; i++) { |
| pass++; |
| ctx->ninsns = 0; |
| |
| bpf_jit_build_prologue(ctx, bpf_is_subprog(prog)); |
| ctx->prologue_len = ctx->ninsns; |
| |
| if (build_body(ctx, extra_pass, ctx->offset)) { |
| prog = orig_prog; |
| goto out_offset; |
| } |
| |
| ctx->epilogue_offset = ctx->ninsns; |
| bpf_jit_build_epilogue(ctx); |
| |
| if (ctx->ninsns == prev_ninsns) { |
| if (jit_data->header) |
| break; |
| /* obtain the actual image size */ |
| extable_size = prog->aux->num_exentries * |
| sizeof(struct exception_table_entry); |
| prog_size = sizeof(*ctx->insns) * ctx->ninsns; |
| |
| jit_data->ro_header = |
| bpf_jit_binary_pack_alloc(prog_size + extable_size, |
| &jit_data->ro_image, sizeof(u32), |
| &jit_data->header, &jit_data->image, |
| bpf_fill_ill_insns); |
| if (!jit_data->ro_header) { |
| prog = orig_prog; |
| goto out_offset; |
| } |
| |
| /* |
| * Use the image(RW) for writing the JITed instructions. But also save |
| * the ro_image(RX) for calculating the offsets in the image. The RW |
| * image will be later copied to the RX image from where the program |
| * will run. The bpf_jit_binary_pack_finalize() will do this copy in the |
| * final step. |
| */ |
| ctx->ro_insns = (u16 *)jit_data->ro_image; |
| ctx->insns = (u16 *)jit_data->image; |
| /* |
| * Now, when the image is allocated, the image can |
| * potentially shrink more (auipc/jalr -> jal). |
| */ |
| } |
| prev_ninsns = ctx->ninsns; |
| } |
| |
| if (i == NR_JIT_ITERATIONS) { |
| pr_err("bpf-jit: image did not converge in <%d passes!\n", i); |
| prog = orig_prog; |
| goto out_free_hdr; |
| } |
| |
| if (extable_size) |
| prog->aux->extable = (void *)ctx->ro_insns + prog_size; |
| |
| skip_init_ctx: |
| pass++; |
| ctx->ninsns = 0; |
| ctx->nexentries = 0; |
| |
| bpf_jit_build_prologue(ctx, bpf_is_subprog(prog)); |
| if (build_body(ctx, extra_pass, NULL)) { |
| prog = orig_prog; |
| goto out_free_hdr; |
| } |
| bpf_jit_build_epilogue(ctx); |
| |
| if (bpf_jit_enable > 1) |
| bpf_jit_dump(prog->len, prog_size, pass, ctx->insns); |
| |
| prog->bpf_func = (void *)ctx->ro_insns + cfi_get_offset(); |
| prog->jited = 1; |
| prog->jited_len = prog_size - cfi_get_offset(); |
| |
| if (!prog->is_func || extra_pass) { |
| if (WARN_ON(bpf_jit_binary_pack_finalize(jit_data->ro_header, jit_data->header))) { |
| /* ro_header has been freed */ |
| jit_data->ro_header = NULL; |
| prog = orig_prog; |
| goto out_offset; |
| } |
| /* |
| * The instructions have now been copied to the ROX region from |
| * where they will execute. |
| * Write any modified data cache blocks out to memory and |
| * invalidate the corresponding blocks in the instruction cache. |
| */ |
| bpf_flush_icache(jit_data->ro_header, ctx->ro_insns + ctx->ninsns); |
| for (i = 0; i < prog->len; i++) |
| ctx->offset[i] = ninsns_rvoff(ctx->offset[i]); |
| bpf_prog_fill_jited_linfo(prog, ctx->offset); |
| out_offset: |
| kfree(ctx->offset); |
| kfree(jit_data); |
| prog->aux->jit_data = NULL; |
| } |
| out: |
| |
| if (tmp_blinded) |
| bpf_jit_prog_release_other(prog, prog == orig_prog ? |
| tmp : orig_prog); |
| return prog; |
| |
| out_free_hdr: |
| if (jit_data->header) { |
| bpf_arch_text_copy(&jit_data->ro_header->size, &jit_data->header->size, |
| sizeof(jit_data->header->size)); |
| bpf_jit_binary_pack_free(jit_data->ro_header, jit_data->header); |
| } |
| goto out_offset; |
| } |
| |
| u64 bpf_jit_alloc_exec_limit(void) |
| { |
| return BPF_JIT_REGION_SIZE; |
| } |
| |
| void *bpf_arch_text_copy(void *dst, void *src, size_t len) |
| { |
| int ret; |
| |
| mutex_lock(&text_mutex); |
| ret = patch_text_nosync(dst, src, len); |
| mutex_unlock(&text_mutex); |
| |
| if (ret) |
| return ERR_PTR(-EINVAL); |
| |
| return dst; |
| } |
| |
| int bpf_arch_text_invalidate(void *dst, size_t len) |
| { |
| int ret; |
| |
| mutex_lock(&text_mutex); |
| ret = patch_text_set_nosync(dst, 0, len); |
| mutex_unlock(&text_mutex); |
| |
| return ret; |
| } |
| |
| void bpf_jit_free(struct bpf_prog *prog) |
| { |
| if (prog->jited) { |
| struct rv_jit_data *jit_data = prog->aux->jit_data; |
| struct bpf_binary_header *hdr; |
| |
| /* |
| * If we fail the final pass of JIT (from jit_subprogs), |
| * the program may not be finalized yet. Call finalize here |
| * before freeing it. |
| */ |
| if (jit_data) { |
| bpf_jit_binary_pack_finalize(jit_data->ro_header, jit_data->header); |
| kfree(jit_data); |
| } |
| hdr = bpf_jit_binary_pack_hdr(prog); |
| bpf_jit_binary_pack_free(hdr, NULL); |
| WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(prog)); |
| } |
| |
| bpf_prog_unlock_free(prog); |
| } |