1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Common functionality for HPPA32 and HPPA64 BPF JIT compilers
4 *
5 * Copyright (c) 2023 Helge Deller <deller@gmx.de>
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	35
15
16static int build_body(struct hppa_jit_context *ctx, bool extra_pass, int *offset)
17{
18	const struct bpf_prog *prog = ctx->prog;
19	int i;
20
21	ctx->reg_seen_collect = true;
22	for (i = 0; i < prog->len; i++) {
23		const struct bpf_insn *insn = &prog->insnsi[i];
24		int ret;
25
26		ret = bpf_jit_emit_insn(insn, ctx, extra_pass);
27		/* BPF_LD | BPF_IMM | BPF_DW: skip the next instruction. */
28		if (ret > 0)
29			i++;
30		if (offset)
31			offset[i] = ctx->ninsns;
32		if (ret < 0)
33			return ret;
34	}
35	ctx->reg_seen_collect = false;
36	return 0;
37}
38
39bool bpf_jit_needs_zext(void)
40{
41	return true;
42}
43
44struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
45{
46	unsigned int prog_size = 0, extable_size = 0;
47	bool tmp_blinded = false, extra_pass = false;
48	struct bpf_prog *tmp, *orig_prog = prog;
49	int pass = 0, prev_ninsns = 0, prologue_len, i;
50	struct hppa_jit_data *jit_data;
51	struct hppa_jit_context *ctx;
52
53	if (!prog->jit_requested)
54		return orig_prog;
55
56	tmp = bpf_jit_blind_constants(prog);
57	if (IS_ERR(tmp))
58		return orig_prog;
59	if (tmp != prog) {
60		tmp_blinded = true;
61		prog = tmp;
62	}
63
64	jit_data = prog->aux->jit_data;
65	if (!jit_data) {
66		jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
67		if (!jit_data) {
68			prog = orig_prog;
69			goto out;
70		}
71		prog->aux->jit_data = jit_data;
72	}
73
74	ctx = &jit_data->ctx;
75
76	if (ctx->offset) {
77		extra_pass = true;
78		prog_size = sizeof(*ctx->insns) * ctx->ninsns;
79		goto skip_init_ctx;
80	}
81
82	ctx->prog = prog;
83	ctx->offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL);
84	if (!ctx->offset) {
85		prog = orig_prog;
86		goto out_offset;
87	}
88	for (i = 0; i < prog->len; i++) {
89		prev_ninsns += 20;
90		ctx->offset[i] = prev_ninsns;
91	}
92
93	for (i = 0; i < NR_JIT_ITERATIONS; i++) {
94		pass++;
95		ctx->ninsns = 0;
96		if (build_body(ctx, extra_pass, ctx->offset)) {
97			prog = orig_prog;
98			goto out_offset;
99		}
100		ctx->body_len = ctx->ninsns;
101		bpf_jit_build_prologue(ctx);
102		ctx->prologue_len = ctx->ninsns - ctx->body_len;
103		ctx->epilogue_offset = ctx->ninsns;
104		bpf_jit_build_epilogue(ctx);
105
106		if (ctx->ninsns == prev_ninsns) {
107			if (jit_data->header)
108				break;
109			/* obtain the actual image size */
110			extable_size = prog->aux->num_exentries *
111				sizeof(struct exception_table_entry);
112			prog_size = sizeof(*ctx->insns) * ctx->ninsns;
113
114			jit_data->header =
115				bpf_jit_binary_alloc(prog_size + extable_size,
116						     &jit_data->image,
117						     sizeof(u32),
118						     bpf_fill_ill_insns);
119			if (!jit_data->header) {
120				prog = orig_prog;
121				goto out_offset;
122			}
123
124			ctx->insns = (u32 *)jit_data->image;
125			/*
126			 * Now, when the image is allocated, the image can
127			 * potentially shrink more (auipc/jalr -> jal).
128			 */
129		}
130		prev_ninsns = ctx->ninsns;
131	}
132
133	if (i == NR_JIT_ITERATIONS) {
134		pr_err("bpf-jit: image did not converge in <%d passes!\n", i);
135		if (jit_data->header)
136			bpf_jit_binary_free(jit_data->header);
137		prog = orig_prog;
138		goto out_offset;
139	}
140
141	if (extable_size)
142		prog->aux->extable = (void *)ctx->insns + prog_size;
143
144skip_init_ctx:
145	pass++;
146	ctx->ninsns = 0;
147
148	bpf_jit_build_prologue(ctx);
149	if (build_body(ctx, extra_pass, NULL)) {
150		bpf_jit_binary_free(jit_data->header);
151		prog = orig_prog;
152		goto out_offset;
153	}
154	bpf_jit_build_epilogue(ctx);
155
156	if (HPPA_JIT_DEBUG || bpf_jit_enable > 1) {
157		if (HPPA_JIT_DUMP)
158			bpf_jit_dump(prog->len, prog_size, pass, ctx->insns);
159		if (HPPA_JIT_REBOOT)
160			{ extern int machine_restart(char *); machine_restart(""); }
161	}
162
163	prog->bpf_func = (void *)ctx->insns;
164	prog->jited = 1;
165	prog->jited_len = prog_size;
166
167	bpf_flush_icache(jit_data->header, ctx->insns + ctx->ninsns);
168
169	if (!prog->is_func || extra_pass) {
170		bpf_jit_binary_lock_ro(jit_data->header);
171		prologue_len = ctx->epilogue_offset - ctx->body_len;
172		for (i = 0; i < prog->len; i++)
173			ctx->offset[i] += prologue_len;
174		bpf_prog_fill_jited_linfo(prog, ctx->offset);
175out_offset:
176		kfree(ctx->offset);
177		kfree(jit_data);
178		prog->aux->jit_data = NULL;
179	}
180out:
181	if (HPPA_JIT_REBOOT)
182		{ extern int machine_restart(char *); machine_restart(""); }
183
184	if (tmp_blinded)
185		bpf_jit_prog_release_other(prog, prog == orig_prog ?
186					   tmp : orig_prog);
187	return prog;
188}
189
190u64 hppa_div64(u64 div, u64 divisor)
191{
192	div = div64_u64(div, divisor);
193	return div;
194}
195
196u64 hppa_div64_rem(u64 div, u64 divisor)
197{
198	u64 rem;
199	div64_u64_rem(div, divisor, &rem);
200	return rem;
201}
202