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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * eBPF JIT compiler
4 *
5 * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
6 * IBM Corporation
7 *
8 * Based on the powerpc classic BPF JIT compiler by Matt Evans
9 */
10#include <linux/moduleloader.h>
11#include <asm/cacheflush.h>
12#include <asm/asm-compat.h>
13#include <linux/netdevice.h>
14#include <linux/filter.h>
15#include <linux/if_vlan.h>
16#include <linux/kernel.h>
17#include <linux/memory.h>
18#include <linux/bpf.h>
19
20#include <asm/kprobes.h>
21#include <asm/code-patching.h>
22
23#include "bpf_jit.h"
24
25static void bpf_jit_fill_ill_insns(void *area, unsigned int size)
26{
27 memset32(area, BREAKPOINT_INSTRUCTION, size / 4);
28}
29
30int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr)
31{
32 if (!exit_addr || is_offset_in_branch_range(exit_addr - (ctx->idx * 4))) {
33 PPC_JMP(exit_addr);
34 } else if (ctx->alt_exit_addr) {
35 if (WARN_ON(!is_offset_in_branch_range((long)ctx->alt_exit_addr - (ctx->idx * 4))))
36 return -1;
37 PPC_JMP(ctx->alt_exit_addr);
38 } else {
39 ctx->alt_exit_addr = ctx->idx * 4;
40 bpf_jit_build_epilogue(image, ctx);
41 }
42
43 return 0;
44}
45
46struct powerpc_jit_data {
47 /* address of rw header */
48 struct bpf_binary_header *hdr;
49 /* address of ro final header */
50 struct bpf_binary_header *fhdr;
51 u32 *addrs;
52 u8 *fimage;
53 u32 proglen;
54 struct codegen_context ctx;
55};
56
57bool bpf_jit_needs_zext(void)
58{
59 return true;
60}
61
62struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
63{
64 u32 proglen;
65 u32 alloclen;
66 u8 *image = NULL;
67 u32 *code_base;
68 u32 *addrs;
69 struct powerpc_jit_data *jit_data;
70 struct codegen_context cgctx;
71 int pass;
72 int flen;
73 struct bpf_binary_header *fhdr = NULL;
74 struct bpf_binary_header *hdr = NULL;
75 struct bpf_prog *org_fp = fp;
76 struct bpf_prog *tmp_fp;
77 bool bpf_blinded = false;
78 bool extra_pass = false;
79 u8 *fimage = NULL;
80 u32 *fcode_base;
81 u32 extable_len;
82 u32 fixup_len;
83
84 if (!fp->jit_requested)
85 return org_fp;
86
87 tmp_fp = bpf_jit_blind_constants(org_fp);
88 if (IS_ERR(tmp_fp))
89 return org_fp;
90
91 if (tmp_fp != org_fp) {
92 bpf_blinded = true;
93 fp = tmp_fp;
94 }
95
96 jit_data = fp->aux->jit_data;
97 if (!jit_data) {
98 jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
99 if (!jit_data) {
100 fp = org_fp;
101 goto out;
102 }
103 fp->aux->jit_data = jit_data;
104 }
105
106 flen = fp->len;
107 addrs = jit_data->addrs;
108 if (addrs) {
109 cgctx = jit_data->ctx;
110 /*
111 * JIT compiled to a writable location (image/code_base) first.
112 * It is then moved to the readonly final location (fimage/fcode_base)
113 * using instruction patching.
114 */
115 fimage = jit_data->fimage;
116 fhdr = jit_data->fhdr;
117 proglen = jit_data->proglen;
118 hdr = jit_data->hdr;
119 image = (void *)hdr + ((void *)fimage - (void *)fhdr);
120 extra_pass = true;
121 /* During extra pass, ensure index is reset before repopulating extable entries */
122 cgctx.exentry_idx = 0;
123 goto skip_init_ctx;
124 }
125
126 addrs = kcalloc(flen + 1, sizeof(*addrs), GFP_KERNEL);
127 if (addrs == NULL) {
128 fp = org_fp;
129 goto out_addrs;
130 }
131
132 memset(&cgctx, 0, sizeof(struct codegen_context));
133 bpf_jit_init_reg_mapping(&cgctx);
134
135 /* Make sure that the stack is quadword aligned. */
136 cgctx.stack_size = round_up(fp->aux->stack_depth, 16);
137
138 /* Scouting faux-generate pass 0 */
139 if (bpf_jit_build_body(fp, NULL, NULL, &cgctx, addrs, 0, false)) {
140 /* We hit something illegal or unsupported. */
141 fp = org_fp;
142 goto out_addrs;
143 }
144
145 /*
146 * If we have seen a tail call, we need a second pass.
147 * This is because bpf_jit_emit_common_epilogue() is called
148 * from bpf_jit_emit_tail_call() with a not yet stable ctx->seen.
149 * We also need a second pass if we ended up with too large
150 * a program so as to ensure BPF_EXIT branches are in range.
151 */
152 if (cgctx.seen & SEEN_TAILCALL || !is_offset_in_branch_range((long)cgctx.idx * 4)) {
153 cgctx.idx = 0;
154 if (bpf_jit_build_body(fp, NULL, NULL, &cgctx, addrs, 0, false)) {
155 fp = org_fp;
156 goto out_addrs;
157 }
158 }
159
160 bpf_jit_realloc_regs(&cgctx);
161 /*
162 * Pretend to build prologue, given the features we've seen. This will
163 * update ctgtx.idx as it pretends to output instructions, then we can
164 * calculate total size from idx.
165 */
166 bpf_jit_build_prologue(NULL, &cgctx);
167 addrs[fp->len] = cgctx.idx * 4;
168 bpf_jit_build_epilogue(NULL, &cgctx);
169
170 fixup_len = fp->aux->num_exentries * BPF_FIXUP_LEN * 4;
171 extable_len = fp->aux->num_exentries * sizeof(struct exception_table_entry);
172
173 proglen = cgctx.idx * 4;
174 alloclen = proglen + FUNCTION_DESCR_SIZE + fixup_len + extable_len;
175
176 fhdr = bpf_jit_binary_pack_alloc(alloclen, &fimage, 4, &hdr, &image,
177 bpf_jit_fill_ill_insns);
178 if (!fhdr) {
179 fp = org_fp;
180 goto out_addrs;
181 }
182
183 if (extable_len)
184 fp->aux->extable = (void *)fimage + FUNCTION_DESCR_SIZE + proglen + fixup_len;
185
186skip_init_ctx:
187 code_base = (u32 *)(image + FUNCTION_DESCR_SIZE);
188 fcode_base = (u32 *)(fimage + FUNCTION_DESCR_SIZE);
189
190 /* Code generation passes 1-2 */
191 for (pass = 1; pass < 3; pass++) {
192 /* Now build the prologue, body code & epilogue for real. */
193 cgctx.idx = 0;
194 cgctx.alt_exit_addr = 0;
195 bpf_jit_build_prologue(code_base, &cgctx);
196 if (bpf_jit_build_body(fp, code_base, fcode_base, &cgctx, addrs, pass,
197 extra_pass)) {
198 bpf_arch_text_copy(&fhdr->size, &hdr->size, sizeof(hdr->size));
199 bpf_jit_binary_pack_free(fhdr, hdr);
200 fp = org_fp;
201 goto out_addrs;
202 }
203 bpf_jit_build_epilogue(code_base, &cgctx);
204
205 if (bpf_jit_enable > 1)
206 pr_info("Pass %d: shrink = %d, seen = 0x%x\n", pass,
207 proglen - (cgctx.idx * 4), cgctx.seen);
208 }
209
210 if (bpf_jit_enable > 1)
211 /*
212 * Note that we output the base address of the code_base
213 * rather than image, since opcodes are in code_base.
214 */
215 bpf_jit_dump(flen, proglen, pass, code_base);
216
217#ifdef CONFIG_PPC64_ELF_ABI_V1
218 /* Function descriptor nastiness: Address + TOC */
219 ((u64 *)image)[0] = (u64)fcode_base;
220 ((u64 *)image)[1] = local_paca->kernel_toc;
221#endif
222
223 fp->bpf_func = (void *)fimage;
224 fp->jited = 1;
225 fp->jited_len = proglen + FUNCTION_DESCR_SIZE;
226
227 if (!fp->is_func || extra_pass) {
228 if (bpf_jit_binary_pack_finalize(fp, fhdr, hdr)) {
229 fp = org_fp;
230 goto out_addrs;
231 }
232 bpf_prog_fill_jited_linfo(fp, addrs);
233out_addrs:
234 kfree(addrs);
235 kfree(jit_data);
236 fp->aux->jit_data = NULL;
237 } else {
238 jit_data->addrs = addrs;
239 jit_data->ctx = cgctx;
240 jit_data->proglen = proglen;
241 jit_data->fimage = fimage;
242 jit_data->fhdr = fhdr;
243 jit_data->hdr = hdr;
244 }
245
246out:
247 if (bpf_blinded)
248 bpf_jit_prog_release_other(fp, fp == org_fp ? tmp_fp : org_fp);
249
250 return fp;
251}
252
253/*
254 * The caller should check for (BPF_MODE(code) == BPF_PROBE_MEM) before calling
255 * this function, as this only applies to BPF_PROBE_MEM, for now.
256 */
257int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass,
258 struct codegen_context *ctx, int insn_idx, int jmp_off,
259 int dst_reg)
260{
261 off_t offset;
262 unsigned long pc;
263 struct exception_table_entry *ex, *ex_entry;
264 u32 *fixup;
265
266 /* Populate extable entries only in the last pass */
267 if (pass != 2)
268 return 0;
269
270 if (!fp->aux->extable ||
271 WARN_ON_ONCE(ctx->exentry_idx >= fp->aux->num_exentries))
272 return -EINVAL;
273
274 /*
275 * Program is first written to image before copying to the
276 * final location (fimage). Accordingly, update in the image first.
277 * As all offsets used are relative, copying as is to the
278 * final location should be alright.
279 */
280 pc = (unsigned long)&image[insn_idx];
281 ex = (void *)fp->aux->extable - (void *)fimage + (void *)image;
282
283 fixup = (void *)ex -
284 (fp->aux->num_exentries * BPF_FIXUP_LEN * 4) +
285 (ctx->exentry_idx * BPF_FIXUP_LEN * 4);
286
287 fixup[0] = PPC_RAW_LI(dst_reg, 0);
288 if (IS_ENABLED(CONFIG_PPC32))
289 fixup[1] = PPC_RAW_LI(dst_reg - 1, 0); /* clear higher 32-bit register too */
290
291 fixup[BPF_FIXUP_LEN - 1] =
292 PPC_RAW_BRANCH((long)(pc + jmp_off) - (long)&fixup[BPF_FIXUP_LEN - 1]);
293
294 ex_entry = &ex[ctx->exentry_idx];
295
296 offset = pc - (long)&ex_entry->insn;
297 if (WARN_ON_ONCE(offset >= 0 || offset < INT_MIN))
298 return -ERANGE;
299 ex_entry->insn = offset;
300
301 offset = (long)fixup - (long)&ex_entry->fixup;
302 if (WARN_ON_ONCE(offset >= 0 || offset < INT_MIN))
303 return -ERANGE;
304 ex_entry->fixup = offset;
305
306 ctx->exentry_idx++;
307 return 0;
308}
309
310void *bpf_arch_text_copy(void *dst, void *src, size_t len)
311{
312 int err;
313
314 if (WARN_ON_ONCE(core_kernel_text((unsigned long)dst)))
315 return ERR_PTR(-EINVAL);
316
317 mutex_lock(&text_mutex);
318 err = patch_instructions(dst, src, len, false);
319 mutex_unlock(&text_mutex);
320
321 return err ? ERR_PTR(err) : dst;
322}
323
324int bpf_arch_text_invalidate(void *dst, size_t len)
325{
326 u32 insn = BREAKPOINT_INSTRUCTION;
327 int ret;
328
329 if (WARN_ON_ONCE(core_kernel_text((unsigned long)dst)))
330 return -EINVAL;
331
332 mutex_lock(&text_mutex);
333 ret = patch_instructions(dst, &insn, len, true);
334 mutex_unlock(&text_mutex);
335
336 return ret;
337}
338
339void bpf_jit_free(struct bpf_prog *fp)
340{
341 if (fp->jited) {
342 struct powerpc_jit_data *jit_data = fp->aux->jit_data;
343 struct bpf_binary_header *hdr;
344
345 /*
346 * If we fail the final pass of JIT (from jit_subprogs),
347 * the program may not be finalized yet. Call finalize here
348 * before freeing it.
349 */
350 if (jit_data) {
351 bpf_jit_binary_pack_finalize(fp, jit_data->fhdr, jit_data->hdr);
352 kvfree(jit_data->addrs);
353 kfree(jit_data);
354 }
355 hdr = bpf_jit_binary_pack_hdr(fp);
356 bpf_jit_binary_pack_free(hdr, NULL);
357 WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(fp));
358 }
359
360 bpf_prog_unlock_free(fp);
361}
1/* bpf_jit_comp.c: BPF JIT compiler for PPC64
2 *
3 * Copyright 2011 Matt Evans <matt@ozlabs.org>, IBM Corporation
4 *
5 * Based on the x86 BPF compiler, by Eric Dumazet (eric.dumazet@gmail.com)
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; version 2
10 * of the License.
11 */
12#include <linux/moduleloader.h>
13#include <asm/cacheflush.h>
14#include <linux/netdevice.h>
15#include <linux/filter.h>
16#include <linux/if_vlan.h>
17
18#include "bpf_jit.h"
19
20int bpf_jit_enable __read_mostly;
21
22static inline void bpf_flush_icache(void *start, void *end)
23{
24 smp_wmb();
25 flush_icache_range((unsigned long)start, (unsigned long)end);
26}
27
28static void bpf_jit_build_prologue(struct sk_filter *fp, u32 *image,
29 struct codegen_context *ctx)
30{
31 int i;
32 const struct sock_filter *filter = fp->insns;
33
34 if (ctx->seen & (SEEN_MEM | SEEN_DATAREF)) {
35 /* Make stackframe */
36 if (ctx->seen & SEEN_DATAREF) {
37 /* If we call any helpers (for loads), save LR */
38 EMIT(PPC_INST_MFLR | __PPC_RT(R0));
39 PPC_STD(0, 1, 16);
40
41 /* Back up non-volatile regs. */
42 PPC_STD(r_D, 1, -(8*(32-r_D)));
43 PPC_STD(r_HL, 1, -(8*(32-r_HL)));
44 }
45 if (ctx->seen & SEEN_MEM) {
46 /*
47 * Conditionally save regs r15-r31 as some will be used
48 * for M[] data.
49 */
50 for (i = r_M; i < (r_M+16); i++) {
51 if (ctx->seen & (1 << (i-r_M)))
52 PPC_STD(i, 1, -(8*(32-i)));
53 }
54 }
55 EMIT(PPC_INST_STDU | __PPC_RS(R1) | __PPC_RA(R1) |
56 (-BPF_PPC_STACKFRAME & 0xfffc));
57 }
58
59 if (ctx->seen & SEEN_DATAREF) {
60 /*
61 * If this filter needs to access skb data,
62 * prepare r_D and r_HL:
63 * r_HL = skb->len - skb->data_len
64 * r_D = skb->data
65 */
66 PPC_LWZ_OFFS(r_scratch1, r_skb, offsetof(struct sk_buff,
67 data_len));
68 PPC_LWZ_OFFS(r_HL, r_skb, offsetof(struct sk_buff, len));
69 PPC_SUB(r_HL, r_HL, r_scratch1);
70 PPC_LD_OFFS(r_D, r_skb, offsetof(struct sk_buff, data));
71 }
72
73 if (ctx->seen & SEEN_XREG) {
74 /*
75 * TODO: Could also detect whether first instr. sets X and
76 * avoid this (as below, with A).
77 */
78 PPC_LI(r_X, 0);
79 }
80
81 switch (filter[0].code) {
82 case BPF_S_RET_K:
83 case BPF_S_LD_W_LEN:
84 case BPF_S_ANC_PROTOCOL:
85 case BPF_S_ANC_IFINDEX:
86 case BPF_S_ANC_MARK:
87 case BPF_S_ANC_RXHASH:
88 case BPF_S_ANC_VLAN_TAG:
89 case BPF_S_ANC_VLAN_TAG_PRESENT:
90 case BPF_S_ANC_CPU:
91 case BPF_S_ANC_QUEUE:
92 case BPF_S_LD_W_ABS:
93 case BPF_S_LD_H_ABS:
94 case BPF_S_LD_B_ABS:
95 /* first instruction sets A register (or is RET 'constant') */
96 break;
97 default:
98 /* make sure we dont leak kernel information to user */
99 PPC_LI(r_A, 0);
100 }
101}
102
103static void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx)
104{
105 int i;
106
107 if (ctx->seen & (SEEN_MEM | SEEN_DATAREF)) {
108 PPC_ADDI(1, 1, BPF_PPC_STACKFRAME);
109 if (ctx->seen & SEEN_DATAREF) {
110 PPC_LD(0, 1, 16);
111 PPC_MTLR(0);
112 PPC_LD(r_D, 1, -(8*(32-r_D)));
113 PPC_LD(r_HL, 1, -(8*(32-r_HL)));
114 }
115 if (ctx->seen & SEEN_MEM) {
116 /* Restore any saved non-vol registers */
117 for (i = r_M; i < (r_M+16); i++) {
118 if (ctx->seen & (1 << (i-r_M)))
119 PPC_LD(i, 1, -(8*(32-i)));
120 }
121 }
122 }
123 /* The RETs have left a return value in R3. */
124
125 PPC_BLR();
126}
127
128#define CHOOSE_LOAD_FUNC(K, func) \
129 ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset)
130
131/* Assemble the body code between the prologue & epilogue. */
132static int bpf_jit_build_body(struct sk_filter *fp, u32 *image,
133 struct codegen_context *ctx,
134 unsigned int *addrs)
135{
136 const struct sock_filter *filter = fp->insns;
137 int flen = fp->len;
138 u8 *func;
139 unsigned int true_cond;
140 int i;
141
142 /* Start of epilogue code */
143 unsigned int exit_addr = addrs[flen];
144
145 for (i = 0; i < flen; i++) {
146 unsigned int K = filter[i].k;
147
148 /*
149 * addrs[] maps a BPF bytecode address into a real offset from
150 * the start of the body code.
151 */
152 addrs[i] = ctx->idx * 4;
153
154 switch (filter[i].code) {
155 /*** ALU ops ***/
156 case BPF_S_ALU_ADD_X: /* A += X; */
157 ctx->seen |= SEEN_XREG;
158 PPC_ADD(r_A, r_A, r_X);
159 break;
160 case BPF_S_ALU_ADD_K: /* A += K; */
161 if (!K)
162 break;
163 PPC_ADDI(r_A, r_A, IMM_L(K));
164 if (K >= 32768)
165 PPC_ADDIS(r_A, r_A, IMM_HA(K));
166 break;
167 case BPF_S_ALU_SUB_X: /* A -= X; */
168 ctx->seen |= SEEN_XREG;
169 PPC_SUB(r_A, r_A, r_X);
170 break;
171 case BPF_S_ALU_SUB_K: /* A -= K */
172 if (!K)
173 break;
174 PPC_ADDI(r_A, r_A, IMM_L(-K));
175 if (K >= 32768)
176 PPC_ADDIS(r_A, r_A, IMM_HA(-K));
177 break;
178 case BPF_S_ALU_MUL_X: /* A *= X; */
179 ctx->seen |= SEEN_XREG;
180 PPC_MUL(r_A, r_A, r_X);
181 break;
182 case BPF_S_ALU_MUL_K: /* A *= K */
183 if (K < 32768)
184 PPC_MULI(r_A, r_A, K);
185 else {
186 PPC_LI32(r_scratch1, K);
187 PPC_MUL(r_A, r_A, r_scratch1);
188 }
189 break;
190 case BPF_S_ALU_MOD_X: /* A %= X; */
191 ctx->seen |= SEEN_XREG;
192 PPC_CMPWI(r_X, 0);
193 if (ctx->pc_ret0 != -1) {
194 PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]);
195 } else {
196 PPC_BCC_SHORT(COND_NE, (ctx->idx*4)+12);
197 PPC_LI(r_ret, 0);
198 PPC_JMP(exit_addr);
199 }
200 PPC_DIVWU(r_scratch1, r_A, r_X);
201 PPC_MUL(r_scratch1, r_X, r_scratch1);
202 PPC_SUB(r_A, r_A, r_scratch1);
203 break;
204 case BPF_S_ALU_MOD_K: /* A %= K; */
205 PPC_LI32(r_scratch2, K);
206 PPC_DIVWU(r_scratch1, r_A, r_scratch2);
207 PPC_MUL(r_scratch1, r_scratch2, r_scratch1);
208 PPC_SUB(r_A, r_A, r_scratch1);
209 break;
210 case BPF_S_ALU_DIV_X: /* A /= X; */
211 ctx->seen |= SEEN_XREG;
212 PPC_CMPWI(r_X, 0);
213 if (ctx->pc_ret0 != -1) {
214 PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]);
215 } else {
216 /*
217 * Exit, returning 0; first pass hits here
218 * (longer worst-case code size).
219 */
220 PPC_BCC_SHORT(COND_NE, (ctx->idx*4)+12);
221 PPC_LI(r_ret, 0);
222 PPC_JMP(exit_addr);
223 }
224 PPC_DIVWU(r_A, r_A, r_X);
225 break;
226 case BPF_S_ALU_DIV_K: /* A /= K */
227 if (K == 1)
228 break;
229 PPC_LI32(r_scratch1, K);
230 PPC_DIVWU(r_A, r_A, r_scratch1);
231 break;
232 case BPF_S_ALU_AND_X:
233 ctx->seen |= SEEN_XREG;
234 PPC_AND(r_A, r_A, r_X);
235 break;
236 case BPF_S_ALU_AND_K:
237 if (!IMM_H(K))
238 PPC_ANDI(r_A, r_A, K);
239 else {
240 PPC_LI32(r_scratch1, K);
241 PPC_AND(r_A, r_A, r_scratch1);
242 }
243 break;
244 case BPF_S_ALU_OR_X:
245 ctx->seen |= SEEN_XREG;
246 PPC_OR(r_A, r_A, r_X);
247 break;
248 case BPF_S_ALU_OR_K:
249 if (IMM_L(K))
250 PPC_ORI(r_A, r_A, IMM_L(K));
251 if (K >= 65536)
252 PPC_ORIS(r_A, r_A, IMM_H(K));
253 break;
254 case BPF_S_ANC_ALU_XOR_X:
255 case BPF_S_ALU_XOR_X: /* A ^= X */
256 ctx->seen |= SEEN_XREG;
257 PPC_XOR(r_A, r_A, r_X);
258 break;
259 case BPF_S_ALU_XOR_K: /* A ^= K */
260 if (IMM_L(K))
261 PPC_XORI(r_A, r_A, IMM_L(K));
262 if (K >= 65536)
263 PPC_XORIS(r_A, r_A, IMM_H(K));
264 break;
265 case BPF_S_ALU_LSH_X: /* A <<= X; */
266 ctx->seen |= SEEN_XREG;
267 PPC_SLW(r_A, r_A, r_X);
268 break;
269 case BPF_S_ALU_LSH_K:
270 if (K == 0)
271 break;
272 else
273 PPC_SLWI(r_A, r_A, K);
274 break;
275 case BPF_S_ALU_RSH_X: /* A >>= X; */
276 ctx->seen |= SEEN_XREG;
277 PPC_SRW(r_A, r_A, r_X);
278 break;
279 case BPF_S_ALU_RSH_K: /* A >>= K; */
280 if (K == 0)
281 break;
282 else
283 PPC_SRWI(r_A, r_A, K);
284 break;
285 case BPF_S_ALU_NEG:
286 PPC_NEG(r_A, r_A);
287 break;
288 case BPF_S_RET_K:
289 PPC_LI32(r_ret, K);
290 if (!K) {
291 if (ctx->pc_ret0 == -1)
292 ctx->pc_ret0 = i;
293 }
294 /*
295 * If this isn't the very last instruction, branch to
296 * the epilogue if we've stuff to clean up. Otherwise,
297 * if there's nothing to tidy, just return. If we /are/
298 * the last instruction, we're about to fall through to
299 * the epilogue to return.
300 */
301 if (i != flen - 1) {
302 /*
303 * Note: 'seen' is properly valid only on pass
304 * #2. Both parts of this conditional are the
305 * same instruction size though, meaning the
306 * first pass will still correctly determine the
307 * code size/addresses.
308 */
309 if (ctx->seen)
310 PPC_JMP(exit_addr);
311 else
312 PPC_BLR();
313 }
314 break;
315 case BPF_S_RET_A:
316 PPC_MR(r_ret, r_A);
317 if (i != flen - 1) {
318 if (ctx->seen)
319 PPC_JMP(exit_addr);
320 else
321 PPC_BLR();
322 }
323 break;
324 case BPF_S_MISC_TAX: /* X = A */
325 PPC_MR(r_X, r_A);
326 break;
327 case BPF_S_MISC_TXA: /* A = X */
328 ctx->seen |= SEEN_XREG;
329 PPC_MR(r_A, r_X);
330 break;
331
332 /*** Constant loads/M[] access ***/
333 case BPF_S_LD_IMM: /* A = K */
334 PPC_LI32(r_A, K);
335 break;
336 case BPF_S_LDX_IMM: /* X = K */
337 PPC_LI32(r_X, K);
338 break;
339 case BPF_S_LD_MEM: /* A = mem[K] */
340 PPC_MR(r_A, r_M + (K & 0xf));
341 ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
342 break;
343 case BPF_S_LDX_MEM: /* X = mem[K] */
344 PPC_MR(r_X, r_M + (K & 0xf));
345 ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
346 break;
347 case BPF_S_ST: /* mem[K] = A */
348 PPC_MR(r_M + (K & 0xf), r_A);
349 ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
350 break;
351 case BPF_S_STX: /* mem[K] = X */
352 PPC_MR(r_M + (K & 0xf), r_X);
353 ctx->seen |= SEEN_XREG | SEEN_MEM | (1<<(K & 0xf));
354 break;
355 case BPF_S_LD_W_LEN: /* A = skb->len; */
356 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
357 PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff, len));
358 break;
359 case BPF_S_LDX_W_LEN: /* X = skb->len; */
360 PPC_LWZ_OFFS(r_X, r_skb, offsetof(struct sk_buff, len));
361 break;
362
363 /*** Ancillary info loads ***/
364 case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
365 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
366 protocol) != 2);
367 PPC_NTOHS_OFFS(r_A, r_skb, offsetof(struct sk_buff,
368 protocol));
369 break;
370 case BPF_S_ANC_IFINDEX:
371 PPC_LD_OFFS(r_scratch1, r_skb, offsetof(struct sk_buff,
372 dev));
373 PPC_CMPDI(r_scratch1, 0);
374 if (ctx->pc_ret0 != -1) {
375 PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]);
376 } else {
377 /* Exit, returning 0; first pass hits here. */
378 PPC_BCC_SHORT(COND_NE, (ctx->idx*4)+12);
379 PPC_LI(r_ret, 0);
380 PPC_JMP(exit_addr);
381 }
382 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
383 ifindex) != 4);
384 PPC_LWZ_OFFS(r_A, r_scratch1,
385 offsetof(struct net_device, ifindex));
386 break;
387 case BPF_S_ANC_MARK:
388 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
389 PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
390 mark));
391 break;
392 case BPF_S_ANC_RXHASH:
393 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4);
394 PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
395 hash));
396 break;
397 case BPF_S_ANC_VLAN_TAG:
398 case BPF_S_ANC_VLAN_TAG_PRESENT:
399 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
400 PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
401 vlan_tci));
402 if (filter[i].code == BPF_S_ANC_VLAN_TAG)
403 PPC_ANDI(r_A, r_A, VLAN_VID_MASK);
404 else
405 PPC_ANDI(r_A, r_A, VLAN_TAG_PRESENT);
406 break;
407 case BPF_S_ANC_QUEUE:
408 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
409 queue_mapping) != 2);
410 PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
411 queue_mapping));
412 break;
413 case BPF_S_ANC_CPU:
414#ifdef CONFIG_SMP
415 /*
416 * PACA ptr is r13:
417 * raw_smp_processor_id() = local_paca->paca_index
418 */
419 BUILD_BUG_ON(FIELD_SIZEOF(struct paca_struct,
420 paca_index) != 2);
421 PPC_LHZ_OFFS(r_A, 13,
422 offsetof(struct paca_struct, paca_index));
423#else
424 PPC_LI(r_A, 0);
425#endif
426 break;
427
428 /*** Absolute loads from packet header/data ***/
429 case BPF_S_LD_W_ABS:
430 func = CHOOSE_LOAD_FUNC(K, sk_load_word);
431 goto common_load;
432 case BPF_S_LD_H_ABS:
433 func = CHOOSE_LOAD_FUNC(K, sk_load_half);
434 goto common_load;
435 case BPF_S_LD_B_ABS:
436 func = CHOOSE_LOAD_FUNC(K, sk_load_byte);
437 common_load:
438 /* Load from [K]. */
439 ctx->seen |= SEEN_DATAREF;
440 PPC_LI64(r_scratch1, func);
441 PPC_MTLR(r_scratch1);
442 PPC_LI32(r_addr, K);
443 PPC_BLRL();
444 /*
445 * Helper returns 'lt' condition on error, and an
446 * appropriate return value in r3
447 */
448 PPC_BCC(COND_LT, exit_addr);
449 break;
450
451 /*** Indirect loads from packet header/data ***/
452 case BPF_S_LD_W_IND:
453 func = sk_load_word;
454 goto common_load_ind;
455 case BPF_S_LD_H_IND:
456 func = sk_load_half;
457 goto common_load_ind;
458 case BPF_S_LD_B_IND:
459 func = sk_load_byte;
460 common_load_ind:
461 /*
462 * Load from [X + K]. Negative offsets are tested for
463 * in the helper functions.
464 */
465 ctx->seen |= SEEN_DATAREF | SEEN_XREG;
466 PPC_LI64(r_scratch1, func);
467 PPC_MTLR(r_scratch1);
468 PPC_ADDI(r_addr, r_X, IMM_L(K));
469 if (K >= 32768)
470 PPC_ADDIS(r_addr, r_addr, IMM_HA(K));
471 PPC_BLRL();
472 /* If error, cr0.LT set */
473 PPC_BCC(COND_LT, exit_addr);
474 break;
475
476 case BPF_S_LDX_B_MSH:
477 func = CHOOSE_LOAD_FUNC(K, sk_load_byte_msh);
478 goto common_load;
479 break;
480
481 /*** Jump and branches ***/
482 case BPF_S_JMP_JA:
483 if (K != 0)
484 PPC_JMP(addrs[i + 1 + K]);
485 break;
486
487 case BPF_S_JMP_JGT_K:
488 case BPF_S_JMP_JGT_X:
489 true_cond = COND_GT;
490 goto cond_branch;
491 case BPF_S_JMP_JGE_K:
492 case BPF_S_JMP_JGE_X:
493 true_cond = COND_GE;
494 goto cond_branch;
495 case BPF_S_JMP_JEQ_K:
496 case BPF_S_JMP_JEQ_X:
497 true_cond = COND_EQ;
498 goto cond_branch;
499 case BPF_S_JMP_JSET_K:
500 case BPF_S_JMP_JSET_X:
501 true_cond = COND_NE;
502 /* Fall through */
503 cond_branch:
504 /* same targets, can avoid doing the test :) */
505 if (filter[i].jt == filter[i].jf) {
506 if (filter[i].jt > 0)
507 PPC_JMP(addrs[i + 1 + filter[i].jt]);
508 break;
509 }
510
511 switch (filter[i].code) {
512 case BPF_S_JMP_JGT_X:
513 case BPF_S_JMP_JGE_X:
514 case BPF_S_JMP_JEQ_X:
515 ctx->seen |= SEEN_XREG;
516 PPC_CMPLW(r_A, r_X);
517 break;
518 case BPF_S_JMP_JSET_X:
519 ctx->seen |= SEEN_XREG;
520 PPC_AND_DOT(r_scratch1, r_A, r_X);
521 break;
522 case BPF_S_JMP_JEQ_K:
523 case BPF_S_JMP_JGT_K:
524 case BPF_S_JMP_JGE_K:
525 if (K < 32768)
526 PPC_CMPLWI(r_A, K);
527 else {
528 PPC_LI32(r_scratch1, K);
529 PPC_CMPLW(r_A, r_scratch1);
530 }
531 break;
532 case BPF_S_JMP_JSET_K:
533 if (K < 32768)
534 /* PPC_ANDI is /only/ dot-form */
535 PPC_ANDI(r_scratch1, r_A, K);
536 else {
537 PPC_LI32(r_scratch1, K);
538 PPC_AND_DOT(r_scratch1, r_A,
539 r_scratch1);
540 }
541 break;
542 }
543 /* Sometimes branches are constructed "backward", with
544 * the false path being the branch and true path being
545 * a fallthrough to the next instruction.
546 */
547 if (filter[i].jt == 0)
548 /* Swap the sense of the branch */
549 PPC_BCC(true_cond ^ COND_CMP_TRUE,
550 addrs[i + 1 + filter[i].jf]);
551 else {
552 PPC_BCC(true_cond, addrs[i + 1 + filter[i].jt]);
553 if (filter[i].jf != 0)
554 PPC_JMP(addrs[i + 1 + filter[i].jf]);
555 }
556 break;
557 default:
558 /* The filter contains something cruel & unusual.
559 * We don't handle it, but also there shouldn't be
560 * anything missing from our list.
561 */
562 if (printk_ratelimit())
563 pr_err("BPF filter opcode %04x (@%d) unsupported\n",
564 filter[i].code, i);
565 return -ENOTSUPP;
566 }
567
568 }
569 /* Set end-of-body-code address for exit. */
570 addrs[i] = ctx->idx * 4;
571
572 return 0;
573}
574
575void bpf_jit_compile(struct sk_filter *fp)
576{
577 unsigned int proglen;
578 unsigned int alloclen;
579 u32 *image = NULL;
580 u32 *code_base;
581 unsigned int *addrs;
582 struct codegen_context cgctx;
583 int pass;
584 int flen = fp->len;
585
586 if (!bpf_jit_enable)
587 return;
588
589 addrs = kzalloc((flen+1) * sizeof(*addrs), GFP_KERNEL);
590 if (addrs == NULL)
591 return;
592
593 /*
594 * There are multiple assembly passes as the generated code will change
595 * size as it settles down, figuring out the max branch offsets/exit
596 * paths required.
597 *
598 * The range of standard conditional branches is +/- 32Kbytes. Since
599 * BPF_MAXINSNS = 4096, we can only jump from (worst case) start to
600 * finish with 8 bytes/instruction. Not feasible, so long jumps are
601 * used, distinct from short branches.
602 *
603 * Current:
604 *
605 * For now, both branch types assemble to 2 words (short branches padded
606 * with a NOP); this is less efficient, but assembly will always complete
607 * after exactly 3 passes:
608 *
609 * First pass: No code buffer; Program is "faux-generated" -- no code
610 * emitted but maximum size of output determined (and addrs[] filled
611 * in). Also, we note whether we use M[], whether we use skb data, etc.
612 * All generation choices assumed to be 'worst-case', e.g. branches all
613 * far (2 instructions), return path code reduction not available, etc.
614 *
615 * Second pass: Code buffer allocated with size determined previously.
616 * Prologue generated to support features we have seen used. Exit paths
617 * determined and addrs[] is filled in again, as code may be slightly
618 * smaller as a result.
619 *
620 * Third pass: Code generated 'for real', and branch destinations
621 * determined from now-accurate addrs[] map.
622 *
623 * Ideal:
624 *
625 * If we optimise this, near branches will be shorter. On the
626 * first assembly pass, we should err on the side of caution and
627 * generate the biggest code. On subsequent passes, branches will be
628 * generated short or long and code size will reduce. With smaller
629 * code, more branches may fall into the short category, and code will
630 * reduce more.
631 *
632 * Finally, if we see one pass generate code the same size as the
633 * previous pass we have converged and should now generate code for
634 * real. Allocating at the end will also save the memory that would
635 * otherwise be wasted by the (small) current code shrinkage.
636 * Preferably, we should do a small number of passes (e.g. 5) and if we
637 * haven't converged by then, get impatient and force code to generate
638 * as-is, even if the odd branch would be left long. The chances of a
639 * long jump are tiny with all but the most enormous of BPF filter
640 * inputs, so we should usually converge on the third pass.
641 */
642
643 cgctx.idx = 0;
644 cgctx.seen = 0;
645 cgctx.pc_ret0 = -1;
646 /* Scouting faux-generate pass 0 */
647 if (bpf_jit_build_body(fp, 0, &cgctx, addrs))
648 /* We hit something illegal or unsupported. */
649 goto out;
650
651 /*
652 * Pretend to build prologue, given the features we've seen. This will
653 * update ctgtx.idx as it pretends to output instructions, then we can
654 * calculate total size from idx.
655 */
656 bpf_jit_build_prologue(fp, 0, &cgctx);
657 bpf_jit_build_epilogue(0, &cgctx);
658
659 proglen = cgctx.idx * 4;
660 alloclen = proglen + FUNCTION_DESCR_SIZE;
661 image = module_alloc(alloclen);
662 if (!image)
663 goto out;
664
665 code_base = image + (FUNCTION_DESCR_SIZE/4);
666
667 /* Code generation passes 1-2 */
668 for (pass = 1; pass < 3; pass++) {
669 /* Now build the prologue, body code & epilogue for real. */
670 cgctx.idx = 0;
671 bpf_jit_build_prologue(fp, code_base, &cgctx);
672 bpf_jit_build_body(fp, code_base, &cgctx, addrs);
673 bpf_jit_build_epilogue(code_base, &cgctx);
674
675 if (bpf_jit_enable > 1)
676 pr_info("Pass %d: shrink = %d, seen = 0x%x\n", pass,
677 proglen - (cgctx.idx * 4), cgctx.seen);
678 }
679
680 if (bpf_jit_enable > 1)
681 /* Note that we output the base address of the code_base
682 * rather than image, since opcodes are in code_base.
683 */
684 bpf_jit_dump(flen, proglen, pass, code_base);
685
686 if (image) {
687 bpf_flush_icache(code_base, code_base + (proglen/4));
688 /* Function descriptor nastiness: Address + TOC */
689 ((u64 *)image)[0] = (u64)code_base;
690 ((u64 *)image)[1] = local_paca->kernel_toc;
691 fp->bpf_func = (void *)image;
692 fp->jited = 1;
693 }
694out:
695 kfree(addrs);
696 return;
697}
698
699void bpf_jit_free(struct sk_filter *fp)
700{
701 if (fp->jited)
702 module_free(NULL, fp->bpf_func);
703 kfree(fp);
704}