1 files changed, 281 insertions, 0 deletions
diff --git a/arch/riscv/net/bpf_jit_core.c b/arch/riscv/net/bpf_jit_core.c
new file mode 100644
index 000000000000..6b3acac30c06
--- /dev/null
+++ b/arch/riscv/net/bpf_jit_core.c
@@ -0,0 +1,281 @@
+// 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->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(prog, 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_jit_alloc_exec(unsigned long size)
+{
+	return __vmalloc_node_range(size, PAGE_SIZE, BPF_JIT_REGION_START,
+				    BPF_JIT_REGION_END, GFP_KERNEL,
+				    PAGE_KERNEL, 0, NUMA_NO_NODE,
+				    __builtin_return_address(0));
+}
+
+void bpf_jit_free_exec(void *addr)
+{
+	return vfree(addr);
+}
+
+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(prog, 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);
+}