arch/riscv/net/bpf_jit_core.c

Source file repositories/reference/linux-study-clean/arch/riscv/net/bpf_jit_core.c

File Facts

System
Linux kernel
Corpus path
arch/riscv/net/bpf_jit_core.c
Extension
.c
Size
5774 bytes
Lines
245
Domain
Architecture Layer
Bucket
arch/riscv
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

if (!jit_data) {
			return prog;
		}
		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 = kzalloc_objs(int, prog->len);
	if (!ctx->offset)
		goto out_offset;

	if (build_body(ctx, extra_pass, NULL))
		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))
			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)
				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);
		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))

Annotation

Implementation Notes