1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * BPF JIT compiler for ARM64
4 *
5 * Copyright (C) 2014-2016 Zi Shen Lim <zlim.lnx@gmail.com>
6 */
7
8 #define pr_fmt(fmt) "bpf_jit: " fmt
9
10 #include <linux/arm-smccc.h>
11 #include <linux/bitfield.h>
12 #include <linux/bpf.h>
13 #include <linux/cfi.h>
14 #include <linux/filter.h>
15 #include <linux/memory.h>
16 #include <linux/printk.h>
17 #include <linux/slab.h>
18
19 #include <asm/asm-extable.h>
20 #include <asm/byteorder.h>
21 #include <asm/cacheflush.h>
22 #include <asm/cpufeature.h>
23 #include <asm/debug-monitors.h>
24 #include <asm/insn.h>
25 #include <asm/text-patching.h>
26 #include <asm/set_memory.h>
27
28 #include "bpf_jit.h"
29
30 #define TMP_REG_1 (MAX_BPF_JIT_REG + 0)
31 #define TMP_REG_2 (MAX_BPF_JIT_REG + 1)
32 #define TCCNT_PTR (MAX_BPF_JIT_REG + 2)
33 #define TMP_REG_3 (MAX_BPF_JIT_REG + 3)
34 #define PRIVATE_SP (MAX_BPF_JIT_REG + 4)
35 #define ARENA_VM_START (MAX_BPF_JIT_REG + 5)
36
37 #define check_imm(bits, imm) do { \
38 if ((((imm) > 0) && ((imm) >> (bits))) || \
39 (((imm) < 0) && (~(imm) >> (bits)))) { \
40 pr_info("[%2d] imm=%d(0x%x) out of range\n", \
41 i, imm, imm); \
42 return -EINVAL; \
43 } \
44 } while (0)
45 #define check_imm19(imm) check_imm(19, imm)
46 #define check_imm26(imm) check_imm(26, imm)
47
48 /* Map BPF registers to A64 registers */
49 static const int bpf2a64[] = {
50 /* return value from in-kernel function, and exit value from eBPF */
51 [BPF_REG_0] = A64_R(7),
52 /* arguments from eBPF program to in-kernel function */
53 [BPF_REG_1] = A64_R(0),
54 [BPF_REG_2] = A64_R(1),
55 [BPF_REG_3] = A64_R(2),
56 [BPF_REG_4] = A64_R(3),
57 [BPF_REG_5] = A64_R(4),
58 /* callee saved registers that in-kernel function will preserve */
59 [BPF_REG_6] = A64_R(19),
60 [BPF_REG_7] = A64_R(20),
61 [BPF_REG_8] = A64_R(21),
62 [BPF_REG_9] = A64_R(22),
63 /* read-only frame pointer to access stack */
64 [BPF_REG_FP] = A64_R(25),
65 /* temporary registers for BPF JIT */
66 [TMP_REG_1] = A64_R(10),
67 [TMP_REG_2] = A64_R(11),
68 [TMP_REG_3] = A64_R(12),
69 /* tail_call_cnt_ptr */
70 [TCCNT_PTR] = A64_R(26),
71 /* temporary register for blinding constants */
72 [BPF_REG_AX] = A64_R(9),
73 /* callee saved register for private stack pointer */
74 [PRIVATE_SP] = A64_R(27),
75 /* callee saved register for kern_vm_start address */
76 [ARENA_VM_START] = A64_R(28),
77 };
78
79 struct jit_ctx {
80 const struct bpf_prog *prog;
81 int idx;
82 int epilogue_offset;
83 int *offset;
84 int exentry_idx;
85 int nr_used_callee_reg;
86 u8 used_callee_reg[8]; /* r6~r9, fp, arena_vm_start */
87 __le32 *image;
88 __le32 *ro_image;
89 u32 stack_size;
90 u64 user_vm_start;
91 u64 arena_vm_start;
92 bool fp_used;
93 bool priv_sp_used;
94 bool write;
95 };
96
97 struct bpf_plt {
98 u32 insn_ldr; /* load target */
99 u32 insn_br; /* branch to target */
100 u64 target; /* target value */
101 };
102
103 #define PLT_TARGET_SIZE sizeof_field(struct bpf_plt, target)
104 #define PLT_TARGET_OFFSET offsetof(struct bpf_plt, target)
105
106 /* Memory size/value to protect private stack overflow/underflow */
107 #define PRIV_STACK_GUARD_SZ 16
108 #define PRIV_STACK_GUARD_VAL 0xEB9F12345678eb9fULL
109
emit(const u32 insn,struct jit_ctx * ctx)110 static inline void emit(const u32 insn, struct jit_ctx *ctx)
111 {
112 if (ctx->image != NULL && ctx->write)
113 ctx->image[ctx->idx] = cpu_to_le32(insn);
114
115 ctx->idx++;
116 }
117
emit_u32_data(const u32 data,struct jit_ctx * ctx)118 static inline void emit_u32_data(const u32 data, struct jit_ctx *ctx)
119 {
120 if (ctx->image != NULL && ctx->write)
121 ctx->image[ctx->idx] = data;
122
123 ctx->idx++;
124 }
125
emit_a64_mov_i(const int is64,const int reg,const s32 val,struct jit_ctx * ctx)126 static inline void emit_a64_mov_i(const int is64, const int reg,
127 const s32 val, struct jit_ctx *ctx)
128 {
129 u16 hi = val >> 16;
130 u16 lo = val & 0xffff;
131
132 if (hi & 0x8000) {
133 if (hi == 0xffff) {
134 emit(A64_MOVN(is64, reg, (u16)~lo, 0), ctx);
135 } else {
136 emit(A64_MOVN(is64, reg, (u16)~hi, 16), ctx);
137 if (lo != 0xffff)
138 emit(A64_MOVK(is64, reg, lo, 0), ctx);
139 }
140 } else {
141 emit(A64_MOVZ(is64, reg, lo, 0), ctx);
142 if (hi)
143 emit(A64_MOVK(is64, reg, hi, 16), ctx);
144 }
145 }
146
i64_i16_blocks(const u64 val,bool inverse)147 static int i64_i16_blocks(const u64 val, bool inverse)
148 {
149 return (((val >> 0) & 0xffff) != (inverse ? 0xffff : 0x0000)) +
150 (((val >> 16) & 0xffff) != (inverse ? 0xffff : 0x0000)) +
151 (((val >> 32) & 0xffff) != (inverse ? 0xffff : 0x0000)) +
152 (((val >> 48) & 0xffff) != (inverse ? 0xffff : 0x0000));
153 }
154
emit_a64_mov_i64(const int reg,const u64 val,struct jit_ctx * ctx)155 static inline void emit_a64_mov_i64(const int reg, const u64 val,
156 struct jit_ctx *ctx)
157 {
158 u64 nrm_tmp = val, rev_tmp = ~val;
159 bool inverse;
160 int shift;
161
162 if (!(nrm_tmp >> 32))
163 return emit_a64_mov_i(0, reg, (u32)val, ctx);
164
165 inverse = i64_i16_blocks(nrm_tmp, true) < i64_i16_blocks(nrm_tmp, false);
166 shift = max(round_down((inverse ? (fls64(rev_tmp) - 1) :
167 (fls64(nrm_tmp) - 1)), 16), 0);
168 if (inverse)
169 emit(A64_MOVN(1, reg, (rev_tmp >> shift) & 0xffff, shift), ctx);
170 else
171 emit(A64_MOVZ(1, reg, (nrm_tmp >> shift) & 0xffff, shift), ctx);
172 shift -= 16;
173 while (shift >= 0) {
174 if (((nrm_tmp >> shift) & 0xffff) != (inverse ? 0xffff : 0x0000))
175 emit(A64_MOVK(1, reg, (nrm_tmp >> shift) & 0xffff, shift), ctx);
176 shift -= 16;
177 }
178 }
179
emit_bti(u32 insn,struct jit_ctx * ctx)180 static inline void emit_bti(u32 insn, struct jit_ctx *ctx)
181 {
182 if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL))
183 emit(insn, ctx);
184 }
185
emit_kcfi(u32 hash,struct jit_ctx * ctx)186 static inline void emit_kcfi(u32 hash, struct jit_ctx *ctx)
187 {
188 if (IS_ENABLED(CONFIG_CFI))
189 emit_u32_data(hash, ctx);
190 }
191
192 /*
193 * Kernel addresses in the vmalloc space use at most 48 bits, and the
194 * remaining bits are guaranteed to be 0x1. So we can compose the address
195 * with a fixed length movn/movk/movk sequence.
196 */
emit_addr_mov_i64(const int reg,const u64 val,struct jit_ctx * ctx)197 static inline void emit_addr_mov_i64(const int reg, const u64 val,
198 struct jit_ctx *ctx)
199 {
200 u64 tmp = val;
201 int shift = 0;
202
203 emit(A64_MOVN(1, reg, ~tmp & 0xffff, shift), ctx);
204 while (shift < 32) {
205 tmp >>= 16;
206 shift += 16;
207 emit(A64_MOVK(1, reg, tmp & 0xffff, shift), ctx);
208 }
209 }
210
should_emit_indirect_call(long target,const struct jit_ctx * ctx)211 static bool should_emit_indirect_call(long target, const struct jit_ctx *ctx)
212 {
213 long offset;
214
215 /* when ctx->ro_image is not allocated or the target is unknown,
216 * emit indirect call
217 */
218 if (!ctx->ro_image || !target)
219 return true;
220
221 offset = target - (long)&ctx->ro_image[ctx->idx];
222 return offset < -SZ_128M || offset >= SZ_128M;
223 }
224
emit_direct_call(u64 target,struct jit_ctx * ctx)225 static void emit_direct_call(u64 target, struct jit_ctx *ctx)
226 {
227 u32 insn;
228 unsigned long pc;
229
230 pc = (unsigned long)&ctx->ro_image[ctx->idx];
231 insn = aarch64_insn_gen_branch_imm(pc, target, AARCH64_INSN_BRANCH_LINK);
232 emit(insn, ctx);
233 }
234
emit_indirect_call(u64 target,struct jit_ctx * ctx)235 static void emit_indirect_call(u64 target, struct jit_ctx *ctx)
236 {
237 u8 tmp;
238
239 tmp = bpf2a64[TMP_REG_1];
240 emit_addr_mov_i64(tmp, target, ctx);
241 emit(A64_BLR(tmp), ctx);
242 }
243
emit_call(u64 target,struct jit_ctx * ctx)244 static void emit_call(u64 target, struct jit_ctx *ctx)
245 {
246 if (should_emit_indirect_call((long)target, ctx))
247 emit_indirect_call(target, ctx);
248 else
249 emit_direct_call(target, ctx);
250 }
251
bpf2a64_offset(int bpf_insn,int off,const struct jit_ctx * ctx)252 static inline int bpf2a64_offset(int bpf_insn, int off,
253 const struct jit_ctx *ctx)
254 {
255 /* BPF JMP offset is relative to the next instruction */
256 bpf_insn++;
257 /*
258 * Whereas arm64 branch instructions encode the offset
259 * from the branch itself, so we must subtract 1 from the
260 * instruction offset.
261 */
262 return ctx->offset[bpf_insn + off] - (ctx->offset[bpf_insn] - 1);
263 }
264
jit_fill_hole(void * area,unsigned int size)265 static void jit_fill_hole(void *area, unsigned int size)
266 {
267 __le32 *ptr;
268 /* We are guaranteed to have aligned memory. */
269 for (ptr = area; size >= sizeof(u32); size -= sizeof(u32))
270 *ptr++ = cpu_to_le32(AARCH64_BREAK_FAULT);
271 }
272
bpf_arch_text_invalidate(void * dst,size_t len)273 int bpf_arch_text_invalidate(void *dst, size_t len)
274 {
275 if (!aarch64_insn_set(dst, AARCH64_BREAK_FAULT, len))
276 return -EINVAL;
277
278 return 0;
279 }
280
epilogue_offset(const struct jit_ctx * ctx)281 static inline int epilogue_offset(const struct jit_ctx *ctx)
282 {
283 int to = ctx->epilogue_offset;
284 int from = ctx->idx;
285
286 return to - from;
287 }
288
is_addsub_imm(u32 imm)289 static bool is_addsub_imm(u32 imm)
290 {
291 /* Either imm12 or shifted imm12. */
292 return !(imm & ~0xfff) || !(imm & ~0xfff000);
293 }
294
emit_a64_add_i(const bool is64,const int dst,const int src,const int tmp,const s32 imm,struct jit_ctx * ctx)295 static inline void emit_a64_add_i(const bool is64, const int dst, const int src,
296 const int tmp, const s32 imm, struct jit_ctx *ctx)
297 {
298 if (is_addsub_imm(imm)) {
299 emit(A64_ADD_I(is64, dst, src, imm), ctx);
300 } else if (is_addsub_imm(-(u32)imm)) {
301 emit(A64_SUB_I(is64, dst, src, -imm), ctx);
302 } else {
303 emit_a64_mov_i(is64, tmp, imm, ctx);
304 emit(A64_ADD(is64, dst, src, tmp), ctx);
305 }
306 }
307
308 /*
309 * There are 3 types of AArch64 LDR/STR (immediate) instruction:
310 * Post-index, Pre-index, Unsigned offset.
311 *
312 * For BPF ldr/str, the "unsigned offset" type is sufficient.
313 *
314 * "Unsigned offset" type LDR(immediate) format:
315 *
316 * 3 2 1 0
317 * 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
318 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
319 * |x x|1 1 1 0 0 1 0 1| imm12 | Rn | Rt |
320 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
321 * scale
322 *
323 * "Unsigned offset" type STR(immediate) format:
324 * 3 2 1 0
325 * 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
326 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
327 * |x x|1 1 1 0 0 1 0 0| imm12 | Rn | Rt |
328 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
329 * scale
330 *
331 * The offset is calculated from imm12 and scale in the following way:
332 *
333 * offset = (u64)imm12 << scale
334 */
is_lsi_offset(int offset,int scale)335 static bool is_lsi_offset(int offset, int scale)
336 {
337 if (offset < 0)
338 return false;
339
340 if (offset > (0xFFF << scale))
341 return false;
342
343 if (offset & ((1 << scale) - 1))
344 return false;
345
346 return true;
347 }
348
349 /* generated main prog prologue:
350 * bti c // if CONFIG_ARM64_BTI_KERNEL
351 * mov x9, lr
352 * nop // POKE_OFFSET
353 * paciasp // if CONFIG_ARM64_PTR_AUTH_KERNEL
354 * stp x29, lr, [sp, #-16]!
355 * mov x29, sp
356 * stp xzr, x26, [sp, #-16]!
357 * mov x26, sp
358 * // PROLOGUE_OFFSET
359 * // save callee-saved registers
360 */
prepare_bpf_tail_call_cnt(struct jit_ctx * ctx)361 static void prepare_bpf_tail_call_cnt(struct jit_ctx *ctx)
362 {
363 const bool is_main_prog = !bpf_is_subprog(ctx->prog);
364 const u8 ptr = bpf2a64[TCCNT_PTR];
365
366 if (is_main_prog) {
367 /* Initialize tail_call_cnt. */
368 emit(A64_PUSH(A64_ZR, ptr, A64_SP), ctx);
369 emit(A64_MOV(1, ptr, A64_SP), ctx);
370 } else
371 emit(A64_PUSH(ptr, ptr, A64_SP), ctx);
372 }
373
find_used_callee_regs(struct jit_ctx * ctx)374 static void find_used_callee_regs(struct jit_ctx *ctx)
375 {
376 int i;
377 const struct bpf_prog *prog = ctx->prog;
378 const struct bpf_insn *insn = &prog->insnsi[0];
379 int reg_used = 0;
380
381 for (i = 0; i < prog->len; i++, insn++) {
382 if (insn->dst_reg == BPF_REG_6 || insn->src_reg == BPF_REG_6)
383 reg_used |= 1;
384
385 if (insn->dst_reg == BPF_REG_7 || insn->src_reg == BPF_REG_7)
386 reg_used |= 2;
387
388 if (insn->dst_reg == BPF_REG_8 || insn->src_reg == BPF_REG_8)
389 reg_used |= 4;
390
391 if (insn->dst_reg == BPF_REG_9 || insn->src_reg == BPF_REG_9)
392 reg_used |= 8;
393
394 if (insn->dst_reg == BPF_REG_FP || insn->src_reg == BPF_REG_FP) {
395 ctx->fp_used = true;
396 reg_used |= 16;
397 }
398 }
399
400 i = 0;
401 if (reg_used & 1)
402 ctx->used_callee_reg[i++] = bpf2a64[BPF_REG_6];
403
404 if (reg_used & 2)
405 ctx->used_callee_reg[i++] = bpf2a64[BPF_REG_7];
406
407 if (reg_used & 4)
408 ctx->used_callee_reg[i++] = bpf2a64[BPF_REG_8];
409
410 if (reg_used & 8)
411 ctx->used_callee_reg[i++] = bpf2a64[BPF_REG_9];
412
413 if (reg_used & 16) {
414 ctx->used_callee_reg[i++] = bpf2a64[BPF_REG_FP];
415 if (ctx->priv_sp_used)
416 ctx->used_callee_reg[i++] = bpf2a64[PRIVATE_SP];
417 }
418
419 if (ctx->arena_vm_start)
420 ctx->used_callee_reg[i++] = bpf2a64[ARENA_VM_START];
421
422 ctx->nr_used_callee_reg = i;
423 }
424
425 /* Save callee-saved registers */
push_callee_regs(struct jit_ctx * ctx)426 static void push_callee_regs(struct jit_ctx *ctx)
427 {
428 int reg1, reg2, i;
429
430 /*
431 * Program acting as exception boundary should save all ARM64
432 * Callee-saved registers as the exception callback needs to recover
433 * all ARM64 Callee-saved registers in its epilogue.
434 */
435 if (ctx->prog->aux->exception_boundary) {
436 emit(A64_PUSH(A64_R(19), A64_R(20), A64_SP), ctx);
437 emit(A64_PUSH(A64_R(21), A64_R(22), A64_SP), ctx);
438 emit(A64_PUSH(A64_R(23), A64_R(24), A64_SP), ctx);
439 emit(A64_PUSH(A64_R(25), A64_R(26), A64_SP), ctx);
440 emit(A64_PUSH(A64_R(27), A64_R(28), A64_SP), ctx);
441 ctx->fp_used = true;
442 } else {
443 find_used_callee_regs(ctx);
444 for (i = 0; i + 1 < ctx->nr_used_callee_reg; i += 2) {
445 reg1 = ctx->used_callee_reg[i];
446 reg2 = ctx->used_callee_reg[i + 1];
447 emit(A64_PUSH(reg1, reg2, A64_SP), ctx);
448 }
449 if (i < ctx->nr_used_callee_reg) {
450 reg1 = ctx->used_callee_reg[i];
451 /* keep SP 16-byte aligned */
452 emit(A64_PUSH(reg1, A64_ZR, A64_SP), ctx);
453 }
454 }
455 }
456
457 /* Restore callee-saved registers */
pop_callee_regs(struct jit_ctx * ctx)458 static void pop_callee_regs(struct jit_ctx *ctx)
459 {
460 struct bpf_prog_aux *aux = ctx->prog->aux;
461 int reg1, reg2, i;
462
463 /*
464 * Program acting as exception boundary pushes R23 and R24 in addition
465 * to BPF callee-saved registers. Exception callback uses the boundary
466 * program's stack frame, so recover these extra registers in the above
467 * two cases.
468 */
469 if (aux->exception_boundary || aux->exception_cb) {
470 emit(A64_POP(A64_R(27), A64_R(28), A64_SP), ctx);
471 emit(A64_POP(A64_R(25), A64_R(26), A64_SP), ctx);
472 emit(A64_POP(A64_R(23), A64_R(24), A64_SP), ctx);
473 emit(A64_POP(A64_R(21), A64_R(22), A64_SP), ctx);
474 emit(A64_POP(A64_R(19), A64_R(20), A64_SP), ctx);
475 } else {
476 i = ctx->nr_used_callee_reg - 1;
477 if (ctx->nr_used_callee_reg % 2 != 0) {
478 reg1 = ctx->used_callee_reg[i];
479 emit(A64_POP(reg1, A64_ZR, A64_SP), ctx);
480 i--;
481 }
482 while (i > 0) {
483 reg1 = ctx->used_callee_reg[i - 1];
484 reg2 = ctx->used_callee_reg[i];
485 emit(A64_POP(reg1, reg2, A64_SP), ctx);
486 i -= 2;
487 }
488 }
489 }
490
emit_percpu_ptr(const u8 dst_reg,void __percpu * ptr,struct jit_ctx * ctx)491 static void emit_percpu_ptr(const u8 dst_reg, void __percpu *ptr,
492 struct jit_ctx *ctx)
493 {
494 const u8 tmp = bpf2a64[TMP_REG_1];
495
496 emit_a64_mov_i64(dst_reg, (__force const u64)ptr, ctx);
497 if (cpus_have_cap(ARM64_HAS_VIRT_HOST_EXTN))
498 emit(A64_MRS_TPIDR_EL2(tmp), ctx);
499 else
500 emit(A64_MRS_TPIDR_EL1(tmp), ctx);
501 emit(A64_ADD(1, dst_reg, dst_reg, tmp), ctx);
502 }
503
504 #define BTI_INSNS (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) ? 1 : 0)
505 #define PAC_INSNS (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL) ? 1 : 0)
506
507 /* Offset of nop instruction in bpf prog entry to be poked */
508 #define POKE_OFFSET (BTI_INSNS + 1)
509
510 /* Tail call offset to jump into */
511 #define PROLOGUE_OFFSET (BTI_INSNS + 2 + PAC_INSNS + 4)
512
build_prologue(struct jit_ctx * ctx,bool ebpf_from_cbpf)513 static int build_prologue(struct jit_ctx *ctx, bool ebpf_from_cbpf)
514 {
515 const struct bpf_prog *prog = ctx->prog;
516 const bool is_main_prog = !bpf_is_subprog(prog);
517 const u8 fp = bpf2a64[BPF_REG_FP];
518 const u8 arena_vm_base = bpf2a64[ARENA_VM_START];
519 const u8 priv_sp = bpf2a64[PRIVATE_SP];
520 void __percpu *priv_stack_ptr;
521 int cur_offset;
522
523 /*
524 * BPF prog stack layout
525 *
526 * high
527 * original A64_SP => 0:+-----+ BPF prologue
528 * |FP/LR|
529 * current A64_FP => -16:+-----+
530 * | ... | callee saved registers
531 * BPF fp register => -64:+-----+ <= (BPF_FP)
532 * | |
533 * | ... | BPF prog stack
534 * | |
535 * +-----+ <= (BPF_FP - prog->aux->stack_depth)
536 * |RSVD | padding
537 * current A64_SP => +-----+ <= (BPF_FP - ctx->stack_size)
538 * | |
539 * | ... | Function call stack
540 * | |
541 * +-----+
542 * low
543 *
544 */
545
546 emit_kcfi(is_main_prog ? cfi_bpf_hash : cfi_bpf_subprog_hash, ctx);
547 const int idx0 = ctx->idx;
548
549 /* bpf function may be invoked by 3 instruction types:
550 * 1. bl, attached via freplace to bpf prog via short jump
551 * 2. br, attached via freplace to bpf prog via long jump
552 * 3. blr, working as a function pointer, used by emit_call.
553 * So BTI_JC should used here to support both br and blr.
554 */
555 emit_bti(A64_BTI_JC, ctx);
556
557 emit(A64_MOV(1, A64_R(9), A64_LR), ctx);
558 emit(A64_NOP, ctx);
559
560 if (!prog->aux->exception_cb) {
561 /* Sign lr */
562 if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL))
563 emit(A64_PACIASP, ctx);
564
565 /* Save FP and LR registers to stay align with ARM64 AAPCS */
566 emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx);
567 emit(A64_MOV(1, A64_FP, A64_SP), ctx);
568
569 prepare_bpf_tail_call_cnt(ctx);
570
571 if (!ebpf_from_cbpf && is_main_prog) {
572 cur_offset = ctx->idx - idx0;
573 if (cur_offset != PROLOGUE_OFFSET) {
574 pr_err_once("PROLOGUE_OFFSET = %d, expected %d!\n",
575 cur_offset, PROLOGUE_OFFSET);
576 return -1;
577 }
578 /* BTI landing pad for the tail call, done with a BR */
579 emit_bti(A64_BTI_J, ctx);
580 }
581 push_callee_regs(ctx);
582 } else {
583 /*
584 * Exception callback receives FP of Main Program as third
585 * parameter
586 */
587 emit(A64_MOV(1, A64_FP, A64_R(2)), ctx);
588 /*
589 * Main Program already pushed the frame record and the
590 * callee-saved registers. The exception callback will not push
591 * anything and re-use the main program's stack.
592 *
593 * 12 registers are on the stack
594 */
595 emit(A64_SUB_I(1, A64_SP, A64_FP, 96), ctx);
596 }
597
598 /* Stack must be multiples of 16B */
599 ctx->stack_size = round_up(prog->aux->stack_depth, 16);
600
601 if (ctx->fp_used) {
602 if (ctx->priv_sp_used) {
603 /* Set up private stack pointer */
604 priv_stack_ptr = prog->aux->priv_stack_ptr + PRIV_STACK_GUARD_SZ;
605 emit_percpu_ptr(priv_sp, priv_stack_ptr, ctx);
606 emit(A64_ADD_I(1, fp, priv_sp, ctx->stack_size), ctx);
607 } else {
608 /* Set up BPF prog stack base register */
609 emit(A64_MOV(1, fp, A64_SP), ctx);
610 }
611 }
612
613 /* Set up function call stack */
614 if (ctx->stack_size && !ctx->priv_sp_used)
615 emit(A64_SUB_I(1, A64_SP, A64_SP, ctx->stack_size), ctx);
616
617 if (ctx->arena_vm_start)
618 emit_a64_mov_i64(arena_vm_base, ctx->arena_vm_start, ctx);
619
620 return 0;
621 }
622
emit_bpf_tail_call(struct jit_ctx * ctx)623 static int emit_bpf_tail_call(struct jit_ctx *ctx)
624 {
625 /* bpf_tail_call(void *prog_ctx, struct bpf_array *array, u64 index) */
626 const u8 r2 = bpf2a64[BPF_REG_2];
627 const u8 r3 = bpf2a64[BPF_REG_3];
628
629 const u8 tmp = bpf2a64[TMP_REG_1];
630 const u8 prg = bpf2a64[TMP_REG_2];
631 const u8 tcc = bpf2a64[TMP_REG_3];
632 const u8 ptr = bpf2a64[TCCNT_PTR];
633 size_t off;
634 __le32 *branch1 = NULL;
635 __le32 *branch2 = NULL;
636 __le32 *branch3 = NULL;
637
638 /* if (index >= array->map.max_entries)
639 * goto out;
640 */
641 off = offsetof(struct bpf_array, map.max_entries);
642 emit_a64_mov_i64(tmp, off, ctx);
643 emit(A64_LDR32(tmp, r2, tmp), ctx);
644 emit(A64_MOV(0, r3, r3), ctx);
645 emit(A64_CMP(0, r3, tmp), ctx);
646 branch1 = ctx->image + ctx->idx;
647 emit(A64_NOP, ctx);
648
649 /*
650 * if ((*tail_call_cnt_ptr) >= MAX_TAIL_CALL_CNT)
651 * goto out;
652 */
653 emit_a64_mov_i64(tmp, MAX_TAIL_CALL_CNT, ctx);
654 emit(A64_LDR64I(tcc, ptr, 0), ctx);
655 emit(A64_CMP(1, tcc, tmp), ctx);
656 branch2 = ctx->image + ctx->idx;
657 emit(A64_NOP, ctx);
658
659 /* (*tail_call_cnt_ptr)++; */
660 emit(A64_ADD_I(1, tcc, tcc, 1), ctx);
661
662 /* prog = array->ptrs[index];
663 * if (prog == NULL)
664 * goto out;
665 */
666 off = offsetof(struct bpf_array, ptrs);
667 emit_a64_mov_i64(tmp, off, ctx);
668 emit(A64_ADD(1, tmp, r2, tmp), ctx);
669 emit(A64_LSL(1, prg, r3, 3), ctx);
670 emit(A64_LDR64(prg, tmp, prg), ctx);
671 branch3 = ctx->image + ctx->idx;
672 emit(A64_NOP, ctx);
673
674 /* Update tail_call_cnt if the slot is populated. */
675 emit(A64_STR64I(tcc, ptr, 0), ctx);
676
677 /* restore SP */
678 if (ctx->stack_size && !ctx->priv_sp_used)
679 emit(A64_ADD_I(1, A64_SP, A64_SP, ctx->stack_size), ctx);
680
681 pop_callee_regs(ctx);
682
683 /* goto *(prog->bpf_func + prologue_offset); */
684 off = offsetof(struct bpf_prog, bpf_func);
685 emit_a64_mov_i64(tmp, off, ctx);
686 emit(A64_LDR64(tmp, prg, tmp), ctx);
687 emit(A64_ADD_I(1, tmp, tmp, sizeof(u32) * PROLOGUE_OFFSET), ctx);
688 emit(A64_BR(tmp), ctx);
689
690 if (ctx->image) {
691 off = &ctx->image[ctx->idx] - branch1;
692 *branch1 = cpu_to_le32(A64_B_(A64_COND_CS, off));
693
694 off = &ctx->image[ctx->idx] - branch2;
695 *branch2 = cpu_to_le32(A64_B_(A64_COND_CS, off));
696
697 off = &ctx->image[ctx->idx] - branch3;
698 *branch3 = cpu_to_le32(A64_CBZ(1, prg, off));
699 }
700
701 return 0;
702 }
703
emit_atomic_ld_st(const struct bpf_insn * insn,struct jit_ctx * ctx)704 static int emit_atomic_ld_st(const struct bpf_insn *insn, struct jit_ctx *ctx)
705 {
706 const s32 imm = insn->imm;
707 const s16 off = insn->off;
708 const u8 code = insn->code;
709 const bool arena = BPF_MODE(code) == BPF_PROBE_ATOMIC;
710 const u8 arena_vm_base = bpf2a64[ARENA_VM_START];
711 const u8 dst = bpf2a64[insn->dst_reg];
712 const u8 src = bpf2a64[insn->src_reg];
713 const u8 tmp = bpf2a64[TMP_REG_1];
714 u8 reg;
715
716 switch (imm) {
717 case BPF_LOAD_ACQ:
718 reg = src;
719 break;
720 case BPF_STORE_REL:
721 reg = dst;
722 break;
723 default:
724 pr_err_once("unknown atomic load/store op code %02x\n", imm);
725 return -EINVAL;
726 }
727
728 if (off) {
729 emit_a64_add_i(1, tmp, reg, tmp, off, ctx);
730 reg = tmp;
731 }
732 if (arena) {
733 emit(A64_ADD(1, tmp, reg, arena_vm_base), ctx);
734 reg = tmp;
735 }
736
737 switch (imm) {
738 case BPF_LOAD_ACQ:
739 switch (BPF_SIZE(code)) {
740 case BPF_B:
741 emit(A64_LDARB(dst, reg), ctx);
742 break;
743 case BPF_H:
744 emit(A64_LDARH(dst, reg), ctx);
745 break;
746 case BPF_W:
747 emit(A64_LDAR32(dst, reg), ctx);
748 break;
749 case BPF_DW:
750 emit(A64_LDAR64(dst, reg), ctx);
751 break;
752 }
753 break;
754 case BPF_STORE_REL:
755 switch (BPF_SIZE(code)) {
756 case BPF_B:
757 emit(A64_STLRB(src, reg), ctx);
758 break;
759 case BPF_H:
760 emit(A64_STLRH(src, reg), ctx);
761 break;
762 case BPF_W:
763 emit(A64_STLR32(src, reg), ctx);
764 break;
765 case BPF_DW:
766 emit(A64_STLR64(src, reg), ctx);
767 break;
768 }
769 break;
770 default:
771 pr_err_once("unexpected atomic load/store op code %02x\n",
772 imm);
773 return -EINVAL;
774 }
775
776 return 0;
777 }
778
779 #ifdef CONFIG_ARM64_LSE_ATOMICS
emit_lse_atomic(const struct bpf_insn * insn,struct jit_ctx * ctx)780 static int emit_lse_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx)
781 {
782 const u8 code = insn->code;
783 const u8 arena_vm_base = bpf2a64[ARENA_VM_START];
784 const u8 dst = bpf2a64[insn->dst_reg];
785 const u8 src = bpf2a64[insn->src_reg];
786 const u8 tmp = bpf2a64[TMP_REG_1];
787 const u8 tmp2 = bpf2a64[TMP_REG_2];
788 const bool isdw = BPF_SIZE(code) == BPF_DW;
789 const bool arena = BPF_MODE(code) == BPF_PROBE_ATOMIC;
790 const s16 off = insn->off;
791 u8 reg = dst;
792
793 if (off) {
794 emit_a64_add_i(1, tmp, reg, tmp, off, ctx);
795 reg = tmp;
796 }
797 if (arena) {
798 emit(A64_ADD(1, tmp, reg, arena_vm_base), ctx);
799 reg = tmp;
800 }
801
802 switch (insn->imm) {
803 /* lock *(u32/u64 *)(dst_reg + off) <op>= src_reg */
804 case BPF_ADD:
805 emit(A64_STADD(isdw, reg, src), ctx);
806 break;
807 case BPF_AND:
808 emit(A64_MVN(isdw, tmp2, src), ctx);
809 emit(A64_STCLR(isdw, reg, tmp2), ctx);
810 break;
811 case BPF_OR:
812 emit(A64_STSET(isdw, reg, src), ctx);
813 break;
814 case BPF_XOR:
815 emit(A64_STEOR(isdw, reg, src), ctx);
816 break;
817 /* src_reg = atomic_fetch_<op>(dst_reg + off, src_reg) */
818 case BPF_ADD | BPF_FETCH:
819 emit(A64_LDADDAL(isdw, src, reg, src), ctx);
820 break;
821 case BPF_AND | BPF_FETCH:
822 emit(A64_MVN(isdw, tmp2, src), ctx);
823 emit(A64_LDCLRAL(isdw, src, reg, tmp2), ctx);
824 break;
825 case BPF_OR | BPF_FETCH:
826 emit(A64_LDSETAL(isdw, src, reg, src), ctx);
827 break;
828 case BPF_XOR | BPF_FETCH:
829 emit(A64_LDEORAL(isdw, src, reg, src), ctx);
830 break;
831 /* src_reg = atomic_xchg(dst_reg + off, src_reg); */
832 case BPF_XCHG:
833 emit(A64_SWPAL(isdw, src, reg, src), ctx);
834 break;
835 /* r0 = atomic_cmpxchg(dst_reg + off, r0, src_reg); */
836 case BPF_CMPXCHG:
837 emit(A64_CASAL(isdw, src, reg, bpf2a64[BPF_REG_0]), ctx);
838 break;
839 default:
840 pr_err_once("unknown atomic op code %02x\n", insn->imm);
841 return -EINVAL;
842 }
843
844 return 0;
845 }
846 #else
emit_lse_atomic(const struct bpf_insn * insn,struct jit_ctx * ctx)847 static inline int emit_lse_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx)
848 {
849 return -EINVAL;
850 }
851 #endif
852
emit_ll_sc_atomic(const struct bpf_insn * insn,struct jit_ctx * ctx)853 static int emit_ll_sc_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx)
854 {
855 const u8 code = insn->code;
856 const u8 dst = bpf2a64[insn->dst_reg];
857 const u8 src = bpf2a64[insn->src_reg];
858 const u8 tmp = bpf2a64[TMP_REG_1];
859 const u8 tmp2 = bpf2a64[TMP_REG_2];
860 const u8 tmp3 = bpf2a64[TMP_REG_3];
861 const int i = insn - ctx->prog->insnsi;
862 const s32 imm = insn->imm;
863 const s16 off = insn->off;
864 const bool isdw = BPF_SIZE(code) == BPF_DW;
865 u8 reg = dst;
866 s32 jmp_offset;
867
868 if (BPF_MODE(code) == BPF_PROBE_ATOMIC) {
869 /* ll_sc based atomics don't support unsafe pointers yet. */
870 pr_err_once("unknown atomic opcode %02x\n", code);
871 return -EINVAL;
872 }
873
874 if (off) {
875 emit_a64_add_i(1, tmp, reg, tmp, off, ctx);
876 reg = tmp;
877 }
878
879 if (imm == BPF_ADD || imm == BPF_AND ||
880 imm == BPF_OR || imm == BPF_XOR) {
881 /* lock *(u32/u64 *)(dst_reg + off) <op>= src_reg */
882 emit(A64_LDXR(isdw, tmp2, reg), ctx);
883 if (imm == BPF_ADD)
884 emit(A64_ADD(isdw, tmp2, tmp2, src), ctx);
885 else if (imm == BPF_AND)
886 emit(A64_AND(isdw, tmp2, tmp2, src), ctx);
887 else if (imm == BPF_OR)
888 emit(A64_ORR(isdw, tmp2, tmp2, src), ctx);
889 else
890 emit(A64_EOR(isdw, tmp2, tmp2, src), ctx);
891 emit(A64_STXR(isdw, tmp2, reg, tmp3), ctx);
892 jmp_offset = -3;
893 check_imm19(jmp_offset);
894 emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
895 } else if (imm == (BPF_ADD | BPF_FETCH) ||
896 imm == (BPF_AND | BPF_FETCH) ||
897 imm == (BPF_OR | BPF_FETCH) ||
898 imm == (BPF_XOR | BPF_FETCH)) {
899 /* src_reg = atomic_fetch_<op>(dst_reg + off, src_reg) */
900 const u8 ax = bpf2a64[BPF_REG_AX];
901
902 emit(A64_MOV(isdw, ax, src), ctx);
903 emit(A64_LDXR(isdw, src, reg), ctx);
904 if (imm == (BPF_ADD | BPF_FETCH))
905 emit(A64_ADD(isdw, tmp2, src, ax), ctx);
906 else if (imm == (BPF_AND | BPF_FETCH))
907 emit(A64_AND(isdw, tmp2, src, ax), ctx);
908 else if (imm == (BPF_OR | BPF_FETCH))
909 emit(A64_ORR(isdw, tmp2, src, ax), ctx);
910 else
911 emit(A64_EOR(isdw, tmp2, src, ax), ctx);
912 emit(A64_STLXR(isdw, tmp2, reg, tmp3), ctx);
913 jmp_offset = -3;
914 check_imm19(jmp_offset);
915 emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
916 emit(A64_DMB_ISH, ctx);
917 } else if (imm == BPF_XCHG) {
918 /* src_reg = atomic_xchg(dst_reg + off, src_reg); */
919 emit(A64_MOV(isdw, tmp2, src), ctx);
920 emit(A64_LDXR(isdw, src, reg), ctx);
921 emit(A64_STLXR(isdw, tmp2, reg, tmp3), ctx);
922 jmp_offset = -2;
923 check_imm19(jmp_offset);
924 emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
925 emit(A64_DMB_ISH, ctx);
926 } else if (imm == BPF_CMPXCHG) {
927 /* r0 = atomic_cmpxchg(dst_reg + off, r0, src_reg); */
928 const u8 r0 = bpf2a64[BPF_REG_0];
929
930 emit(A64_MOV(isdw, tmp2, r0), ctx);
931 emit(A64_LDXR(isdw, r0, reg), ctx);
932 emit(A64_EOR(isdw, tmp3, r0, tmp2), ctx);
933 jmp_offset = 4;
934 check_imm19(jmp_offset);
935 emit(A64_CBNZ(isdw, tmp3, jmp_offset), ctx);
936 emit(A64_STLXR(isdw, src, reg, tmp3), ctx);
937 jmp_offset = -4;
938 check_imm19(jmp_offset);
939 emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
940 emit(A64_DMB_ISH, ctx);
941 } else {
942 pr_err_once("unknown atomic op code %02x\n", imm);
943 return -EINVAL;
944 }
945
946 return 0;
947 }
948
949 void dummy_tramp(void);
950
951 asm (
952 " .pushsection .text, \"ax\", @progbits\n"
953 " .global dummy_tramp\n"
954 " .type dummy_tramp, %function\n"
955 "dummy_tramp:"
956 #if IS_ENABLED(CONFIG_ARM64_BTI_KERNEL)
957 " bti j\n" /* dummy_tramp is called via "br x10" */
958 #endif
959 " mov x10, x30\n"
960 " mov x30, x9\n"
961 " ret x10\n"
962 " .size dummy_tramp, .-dummy_tramp\n"
963 " .popsection\n"
964 );
965
966 /* build a plt initialized like this:
967 *
968 * plt:
969 * ldr tmp, target
970 * br tmp
971 * target:
972 * .quad dummy_tramp
973 *
974 * when a long jump trampoline is attached, target is filled with the
975 * trampoline address, and when the trampoline is removed, target is
976 * restored to dummy_tramp address.
977 */
build_plt(struct jit_ctx * ctx)978 static void build_plt(struct jit_ctx *ctx)
979 {
980 const u8 tmp = bpf2a64[TMP_REG_1];
981 struct bpf_plt *plt = NULL;
982
983 /* make sure target is 64-bit aligned */
984 if ((ctx->idx + PLT_TARGET_OFFSET / AARCH64_INSN_SIZE) % 2)
985 emit(A64_NOP, ctx);
986
987 plt = (struct bpf_plt *)(ctx->image + ctx->idx);
988 /* plt is called via bl, no BTI needed here */
989 emit(A64_LDR64LIT(tmp, 2 * AARCH64_INSN_SIZE), ctx);
990 emit(A64_BR(tmp), ctx);
991
992 if (ctx->image)
993 plt->target = (u64)&dummy_tramp;
994 }
995
996 /* Clobbers BPF registers 1-4, aka x0-x3 */
build_bhb_mitigation(struct jit_ctx * ctx)997 static void __maybe_unused build_bhb_mitigation(struct jit_ctx *ctx)
998 {
999 const u8 r1 = bpf2a64[BPF_REG_1]; /* aka x0 */
1000 u8 k = get_spectre_bhb_loop_value();
1001
1002 if (!IS_ENABLED(CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY) ||
1003 cpu_mitigations_off() || __nospectre_bhb ||
1004 arm64_get_spectre_v2_state() == SPECTRE_VULNERABLE)
1005 return;
1006
1007 if (capable(CAP_SYS_ADMIN))
1008 return;
1009
1010 if (supports_clearbhb(SCOPE_SYSTEM)) {
1011 emit(aarch64_insn_gen_hint(AARCH64_INSN_HINT_CLEARBHB), ctx);
1012 return;
1013 }
1014
1015 if (k) {
1016 emit_a64_mov_i64(r1, k, ctx);
1017 emit(A64_B(1), ctx);
1018 emit(A64_SUBS_I(true, r1, r1, 1), ctx);
1019 emit(A64_B_(A64_COND_NE, -2), ctx);
1020 emit(aarch64_insn_gen_dsb(AARCH64_INSN_MB_ISH), ctx);
1021 emit(aarch64_insn_get_isb_value(), ctx);
1022 }
1023
1024 if (is_spectre_bhb_fw_mitigated()) {
1025 emit(A64_ORR_I(false, r1, AARCH64_INSN_REG_ZR,
1026 ARM_SMCCC_ARCH_WORKAROUND_3), ctx);
1027 switch (arm_smccc_1_1_get_conduit()) {
1028 case SMCCC_CONDUIT_HVC:
1029 emit(aarch64_insn_get_hvc_value(), ctx);
1030 break;
1031 case SMCCC_CONDUIT_SMC:
1032 emit(aarch64_insn_get_smc_value(), ctx);
1033 break;
1034 default:
1035 pr_err_once("Firmware mitigation enabled with unknown conduit\n");
1036 }
1037 }
1038 }
1039
build_epilogue(struct jit_ctx * ctx,bool was_classic)1040 static void build_epilogue(struct jit_ctx *ctx, bool was_classic)
1041 {
1042 const u8 r0 = bpf2a64[BPF_REG_0];
1043 const u8 ptr = bpf2a64[TCCNT_PTR];
1044
1045 /* We're done with BPF stack */
1046 if (ctx->stack_size && !ctx->priv_sp_used)
1047 emit(A64_ADD_I(1, A64_SP, A64_SP, ctx->stack_size), ctx);
1048
1049 pop_callee_regs(ctx);
1050
1051 emit(A64_POP(A64_ZR, ptr, A64_SP), ctx);
1052
1053 if (was_classic)
1054 build_bhb_mitigation(ctx);
1055
1056 /* Restore FP/LR registers */
1057 emit(A64_POP(A64_FP, A64_LR, A64_SP), ctx);
1058
1059 /* Move the return value from bpf:r0 (aka x7) to x0 */
1060 emit(A64_MOV(1, A64_R(0), r0), ctx);
1061
1062 /* Authenticate lr */
1063 if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL))
1064 emit(A64_AUTIASP, ctx);
1065
1066 emit(A64_RET(A64_LR), ctx);
1067 }
1068
1069 /*
1070 * Metadata encoding for exception handling in JITed code.
1071 *
1072 * Format of `fixup` field in `struct exception_table_entry`:
1073 *
1074 * Bit layout of `fixup` (32-bit):
1075 *
1076 * +-----------+--------+-----------+-----------+----------+
1077 * | 31-27 | 26-22 | 21 | 20-16 | 15-0 |
1078 * | | | | | |
1079 * | FIXUP_REG | Unused | ARENA_ACC | ARENA_REG | OFFSET |
1080 * +-----------+--------+-----------+-----------+----------+
1081 *
1082 * - OFFSET (16 bits): Offset used to compute address for Load/Store instruction.
1083 * - ARENA_REG (5 bits): Register that is used to calculate the address for load/store when
1084 * accessing the arena region.
1085 * - ARENA_ACCESS (1 bit): This bit is set when the faulting instruction accessed the arena region.
1086 * - FIXUP_REG (5 bits): Destination register for the load instruction (cleared on fault) or set to
1087 * DONT_CLEAR if it is a store instruction.
1088 */
1089
1090 #define BPF_FIXUP_OFFSET_MASK GENMASK(15, 0)
1091 #define BPF_FIXUP_ARENA_REG_MASK GENMASK(20, 16)
1092 #define BPF_ARENA_ACCESS BIT(21)
1093 #define BPF_FIXUP_REG_MASK GENMASK(31, 27)
1094 #define DONT_CLEAR 5 /* Unused ARM64 register from BPF's POV */
1095
ex_handler_bpf(const struct exception_table_entry * ex,struct pt_regs * regs)1096 bool ex_handler_bpf(const struct exception_table_entry *ex,
1097 struct pt_regs *regs)
1098 {
1099 int dst_reg = FIELD_GET(BPF_FIXUP_REG_MASK, ex->fixup);
1100 s16 off = FIELD_GET(BPF_FIXUP_OFFSET_MASK, ex->fixup);
1101 int arena_reg = FIELD_GET(BPF_FIXUP_ARENA_REG_MASK, ex->fixup);
1102 bool is_arena = !!(ex->fixup & BPF_ARENA_ACCESS);
1103 bool is_write = (dst_reg == DONT_CLEAR);
1104 unsigned long addr;
1105
1106 if (is_arena) {
1107 addr = regs->regs[arena_reg] + off;
1108 bpf_prog_report_arena_violation(is_write, addr, regs->pc);
1109 }
1110
1111 if (dst_reg != DONT_CLEAR)
1112 regs->regs[dst_reg] = 0;
1113 /* Skip the faulting instruction */
1114 regs->pc += AARCH64_INSN_SIZE;
1115
1116 return true;
1117 }
1118
1119 /* For accesses to BTF pointers, add an entry to the exception table */
add_exception_handler(const struct bpf_insn * insn,struct jit_ctx * ctx,int dst_reg)1120 static int add_exception_handler(const struct bpf_insn *insn,
1121 struct jit_ctx *ctx,
1122 int dst_reg)
1123 {
1124 off_t ins_offset;
1125 s16 off = insn->off;
1126 bool is_arena;
1127 int arena_reg;
1128 unsigned long pc;
1129 struct exception_table_entry *ex;
1130
1131 if (!ctx->image)
1132 /* First pass */
1133 return 0;
1134
1135 if (BPF_MODE(insn->code) != BPF_PROBE_MEM &&
1136 BPF_MODE(insn->code) != BPF_PROBE_MEMSX &&
1137 BPF_MODE(insn->code) != BPF_PROBE_MEM32 &&
1138 BPF_MODE(insn->code) != BPF_PROBE_MEM32SX &&
1139 BPF_MODE(insn->code) != BPF_PROBE_ATOMIC)
1140 return 0;
1141
1142 is_arena = (BPF_MODE(insn->code) == BPF_PROBE_MEM32) ||
1143 (BPF_MODE(insn->code) == BPF_PROBE_MEM32SX) ||
1144 (BPF_MODE(insn->code) == BPF_PROBE_ATOMIC);
1145
1146 if (!ctx->prog->aux->extable ||
1147 WARN_ON_ONCE(ctx->exentry_idx >= ctx->prog->aux->num_exentries))
1148 return -EINVAL;
1149
1150 ex = &ctx->prog->aux->extable[ctx->exentry_idx];
1151 pc = (unsigned long)&ctx->ro_image[ctx->idx - 1];
1152
1153 /*
1154 * This is the relative offset of the instruction that may fault from
1155 * the exception table itself. This will be written to the exception
1156 * table and if this instruction faults, the destination register will
1157 * be set to '0' and the execution will jump to the next instruction.
1158 */
1159 ins_offset = pc - (long)&ex->insn;
1160 if (WARN_ON_ONCE(ins_offset >= 0 || ins_offset < INT_MIN))
1161 return -ERANGE;
1162
1163 /*
1164 * The offsets above have been calculated using the RO buffer but we
1165 * need to use the R/W buffer for writes.
1166 * switch ex to rw buffer for writing.
1167 */
1168 ex = (void *)ctx->image + ((void *)ex - (void *)ctx->ro_image);
1169
1170 ex->insn = ins_offset;
1171
1172 if (BPF_CLASS(insn->code) != BPF_LDX)
1173 dst_reg = DONT_CLEAR;
1174
1175 ex->fixup = FIELD_PREP(BPF_FIXUP_REG_MASK, dst_reg);
1176
1177 if (is_arena) {
1178 ex->fixup |= BPF_ARENA_ACCESS;
1179 /*
1180 * insn->src_reg/dst_reg holds the address in the arena region with upper 32-bits
1181 * being zero because of a preceding addr_space_cast(r<n>, 0x0, 0x1) instruction.
1182 * This address is adjusted with the addition of arena_vm_start (see the
1183 * implementation of BPF_PROBE_MEM32 and BPF_PROBE_ATOMIC) before being used for the
1184 * memory access. Pass the reg holding the unmodified 32-bit address to
1185 * ex_handler_bpf.
1186 */
1187 if (BPF_CLASS(insn->code) == BPF_LDX)
1188 arena_reg = bpf2a64[insn->src_reg];
1189 else
1190 arena_reg = bpf2a64[insn->dst_reg];
1191
1192 ex->fixup |= FIELD_PREP(BPF_FIXUP_OFFSET_MASK, off) |
1193 FIELD_PREP(BPF_FIXUP_ARENA_REG_MASK, arena_reg);
1194 }
1195
1196 ex->type = EX_TYPE_BPF;
1197
1198 ctx->exentry_idx++;
1199 return 0;
1200 }
1201
1202 /* JITs an eBPF instruction.
1203 * Returns:
1204 * 0 - successfully JITed an 8-byte eBPF instruction.
1205 * >0 - successfully JITed a 16-byte eBPF instruction.
1206 * <0 - failed to JIT.
1207 */
build_insn(const struct bpf_insn * insn,struct jit_ctx * ctx,bool extra_pass)1208 static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
1209 bool extra_pass)
1210 {
1211 const u8 code = insn->code;
1212 u8 dst = bpf2a64[insn->dst_reg];
1213 u8 src = bpf2a64[insn->src_reg];
1214 const u8 tmp = bpf2a64[TMP_REG_1];
1215 const u8 tmp2 = bpf2a64[TMP_REG_2];
1216 const u8 tmp3 = bpf2a64[TMP_REG_3];
1217 const u8 fp = bpf2a64[BPF_REG_FP];
1218 const u8 arena_vm_base = bpf2a64[ARENA_VM_START];
1219 const u8 priv_sp = bpf2a64[PRIVATE_SP];
1220 const s16 off = insn->off;
1221 const s32 imm = insn->imm;
1222 const int i = insn - ctx->prog->insnsi;
1223 const bool is64 = BPF_CLASS(code) == BPF_ALU64 ||
1224 BPF_CLASS(code) == BPF_JMP;
1225 u8 jmp_cond;
1226 s32 jmp_offset;
1227 u32 a64_insn;
1228 u8 src_adj;
1229 u8 dst_adj;
1230 int off_adj;
1231 int ret;
1232 bool sign_extend;
1233
1234 switch (code) {
1235 /* dst = src */
1236 case BPF_ALU | BPF_MOV | BPF_X:
1237 case BPF_ALU64 | BPF_MOV | BPF_X:
1238 if (insn_is_cast_user(insn)) {
1239 emit(A64_MOV(0, tmp, src), ctx); // 32-bit mov clears the upper 32 bits
1240 emit_a64_mov_i(0, dst, ctx->user_vm_start >> 32, ctx);
1241 emit(A64_LSL(1, dst, dst, 32), ctx);
1242 emit(A64_CBZ(1, tmp, 2), ctx);
1243 emit(A64_ORR(1, tmp, dst, tmp), ctx);
1244 emit(A64_MOV(1, dst, tmp), ctx);
1245 break;
1246 } else if (insn_is_mov_percpu_addr(insn)) {
1247 if (dst != src)
1248 emit(A64_MOV(1, dst, src), ctx);
1249 if (cpus_have_cap(ARM64_HAS_VIRT_HOST_EXTN))
1250 emit(A64_MRS_TPIDR_EL2(tmp), ctx);
1251 else
1252 emit(A64_MRS_TPIDR_EL1(tmp), ctx);
1253 emit(A64_ADD(1, dst, dst, tmp), ctx);
1254 break;
1255 }
1256 switch (insn->off) {
1257 case 0:
1258 emit(A64_MOV(is64, dst, src), ctx);
1259 break;
1260 case 8:
1261 emit(A64_SXTB(is64, dst, src), ctx);
1262 break;
1263 case 16:
1264 emit(A64_SXTH(is64, dst, src), ctx);
1265 break;
1266 case 32:
1267 emit(A64_SXTW(is64, dst, src), ctx);
1268 break;
1269 }
1270 break;
1271 /* dst = dst OP src */
1272 case BPF_ALU | BPF_ADD | BPF_X:
1273 case BPF_ALU64 | BPF_ADD | BPF_X:
1274 emit(A64_ADD(is64, dst, dst, src), ctx);
1275 break;
1276 case BPF_ALU | BPF_SUB | BPF_X:
1277 case BPF_ALU64 | BPF_SUB | BPF_X:
1278 emit(A64_SUB(is64, dst, dst, src), ctx);
1279 break;
1280 case BPF_ALU | BPF_AND | BPF_X:
1281 case BPF_ALU64 | BPF_AND | BPF_X:
1282 emit(A64_AND(is64, dst, dst, src), ctx);
1283 break;
1284 case BPF_ALU | BPF_OR | BPF_X:
1285 case BPF_ALU64 | BPF_OR | BPF_X:
1286 emit(A64_ORR(is64, dst, dst, src), ctx);
1287 break;
1288 case BPF_ALU | BPF_XOR | BPF_X:
1289 case BPF_ALU64 | BPF_XOR | BPF_X:
1290 emit(A64_EOR(is64, dst, dst, src), ctx);
1291 break;
1292 case BPF_ALU | BPF_MUL | BPF_X:
1293 case BPF_ALU64 | BPF_MUL | BPF_X:
1294 emit(A64_MUL(is64, dst, dst, src), ctx);
1295 break;
1296 case BPF_ALU | BPF_DIV | BPF_X:
1297 case BPF_ALU64 | BPF_DIV | BPF_X:
1298 if (!off)
1299 emit(A64_UDIV(is64, dst, dst, src), ctx);
1300 else
1301 emit(A64_SDIV(is64, dst, dst, src), ctx);
1302 break;
1303 case BPF_ALU | BPF_MOD | BPF_X:
1304 case BPF_ALU64 | BPF_MOD | BPF_X:
1305 if (!off)
1306 emit(A64_UDIV(is64, tmp, dst, src), ctx);
1307 else
1308 emit(A64_SDIV(is64, tmp, dst, src), ctx);
1309 emit(A64_MSUB(is64, dst, dst, tmp, src), ctx);
1310 break;
1311 case BPF_ALU | BPF_LSH | BPF_X:
1312 case BPF_ALU64 | BPF_LSH | BPF_X:
1313 emit(A64_LSLV(is64, dst, dst, src), ctx);
1314 break;
1315 case BPF_ALU | BPF_RSH | BPF_X:
1316 case BPF_ALU64 | BPF_RSH | BPF_X:
1317 emit(A64_LSRV(is64, dst, dst, src), ctx);
1318 break;
1319 case BPF_ALU | BPF_ARSH | BPF_X:
1320 case BPF_ALU64 | BPF_ARSH | BPF_X:
1321 emit(A64_ASRV(is64, dst, dst, src), ctx);
1322 break;
1323 /* dst = -dst */
1324 case BPF_ALU | BPF_NEG:
1325 case BPF_ALU64 | BPF_NEG:
1326 emit(A64_NEG(is64, dst, dst), ctx);
1327 break;
1328 /* dst = BSWAP##imm(dst) */
1329 case BPF_ALU | BPF_END | BPF_FROM_LE:
1330 case BPF_ALU | BPF_END | BPF_FROM_BE:
1331 case BPF_ALU64 | BPF_END | BPF_FROM_LE:
1332 #ifdef CONFIG_CPU_BIG_ENDIAN
1333 if (BPF_CLASS(code) == BPF_ALU && BPF_SRC(code) == BPF_FROM_BE)
1334 goto emit_bswap_uxt;
1335 #else /* !CONFIG_CPU_BIG_ENDIAN */
1336 if (BPF_CLASS(code) == BPF_ALU && BPF_SRC(code) == BPF_FROM_LE)
1337 goto emit_bswap_uxt;
1338 #endif
1339 switch (imm) {
1340 case 16:
1341 emit(A64_REV16(is64, dst, dst), ctx);
1342 /* zero-extend 16 bits into 64 bits */
1343 emit(A64_UXTH(is64, dst, dst), ctx);
1344 break;
1345 case 32:
1346 emit(A64_REV32(0, dst, dst), ctx);
1347 /* upper 32 bits already cleared */
1348 break;
1349 case 64:
1350 emit(A64_REV64(dst, dst), ctx);
1351 break;
1352 }
1353 break;
1354 emit_bswap_uxt:
1355 switch (imm) {
1356 case 16:
1357 /* zero-extend 16 bits into 64 bits */
1358 emit(A64_UXTH(is64, dst, dst), ctx);
1359 break;
1360 case 32:
1361 /* zero-extend 32 bits into 64 bits */
1362 emit(A64_UXTW(is64, dst, dst), ctx);
1363 break;
1364 case 64:
1365 /* nop */
1366 break;
1367 }
1368 break;
1369 /* dst = imm */
1370 case BPF_ALU | BPF_MOV | BPF_K:
1371 case BPF_ALU64 | BPF_MOV | BPF_K:
1372 emit_a64_mov_i(is64, dst, imm, ctx);
1373 break;
1374 /* dst = dst OP imm */
1375 case BPF_ALU | BPF_ADD | BPF_K:
1376 case BPF_ALU64 | BPF_ADD | BPF_K:
1377 emit_a64_add_i(is64, dst, dst, tmp, imm, ctx);
1378 break;
1379 case BPF_ALU | BPF_SUB | BPF_K:
1380 case BPF_ALU64 | BPF_SUB | BPF_K:
1381 if (is_addsub_imm(imm)) {
1382 emit(A64_SUB_I(is64, dst, dst, imm), ctx);
1383 } else if (is_addsub_imm(-(u32)imm)) {
1384 emit(A64_ADD_I(is64, dst, dst, -imm), ctx);
1385 } else {
1386 emit_a64_mov_i(is64, tmp, imm, ctx);
1387 emit(A64_SUB(is64, dst, dst, tmp), ctx);
1388 }
1389 break;
1390 case BPF_ALU | BPF_AND | BPF_K:
1391 case BPF_ALU64 | BPF_AND | BPF_K:
1392 a64_insn = A64_AND_I(is64, dst, dst, imm);
1393 if (a64_insn != AARCH64_BREAK_FAULT) {
1394 emit(a64_insn, ctx);
1395 } else {
1396 emit_a64_mov_i(is64, tmp, imm, ctx);
1397 emit(A64_AND(is64, dst, dst, tmp), ctx);
1398 }
1399 break;
1400 case BPF_ALU | BPF_OR | BPF_K:
1401 case BPF_ALU64 | BPF_OR | BPF_K:
1402 a64_insn = A64_ORR_I(is64, dst, dst, imm);
1403 if (a64_insn != AARCH64_BREAK_FAULT) {
1404 emit(a64_insn, ctx);
1405 } else {
1406 emit_a64_mov_i(is64, tmp, imm, ctx);
1407 emit(A64_ORR(is64, dst, dst, tmp), ctx);
1408 }
1409 break;
1410 case BPF_ALU | BPF_XOR | BPF_K:
1411 case BPF_ALU64 | BPF_XOR | BPF_K:
1412 a64_insn = A64_EOR_I(is64, dst, dst, imm);
1413 if (a64_insn != AARCH64_BREAK_FAULT) {
1414 emit(a64_insn, ctx);
1415 } else {
1416 emit_a64_mov_i(is64, tmp, imm, ctx);
1417 emit(A64_EOR(is64, dst, dst, tmp), ctx);
1418 }
1419 break;
1420 case BPF_ALU | BPF_MUL | BPF_K:
1421 case BPF_ALU64 | BPF_MUL | BPF_K:
1422 emit_a64_mov_i(is64, tmp, imm, ctx);
1423 emit(A64_MUL(is64, dst, dst, tmp), ctx);
1424 break;
1425 case BPF_ALU | BPF_DIV | BPF_K:
1426 case BPF_ALU64 | BPF_DIV | BPF_K:
1427 emit_a64_mov_i(is64, tmp, imm, ctx);
1428 if (!off)
1429 emit(A64_UDIV(is64, dst, dst, tmp), ctx);
1430 else
1431 emit(A64_SDIV(is64, dst, dst, tmp), ctx);
1432 break;
1433 case BPF_ALU | BPF_MOD | BPF_K:
1434 case BPF_ALU64 | BPF_MOD | BPF_K:
1435 emit_a64_mov_i(is64, tmp2, imm, ctx);
1436 if (!off)
1437 emit(A64_UDIV(is64, tmp, dst, tmp2), ctx);
1438 else
1439 emit(A64_SDIV(is64, tmp, dst, tmp2), ctx);
1440 emit(A64_MSUB(is64, dst, dst, tmp, tmp2), ctx);
1441 break;
1442 case BPF_ALU | BPF_LSH | BPF_K:
1443 case BPF_ALU64 | BPF_LSH | BPF_K:
1444 emit(A64_LSL(is64, dst, dst, imm), ctx);
1445 break;
1446 case BPF_ALU | BPF_RSH | BPF_K:
1447 case BPF_ALU64 | BPF_RSH | BPF_K:
1448 emit(A64_LSR(is64, dst, dst, imm), ctx);
1449 break;
1450 case BPF_ALU | BPF_ARSH | BPF_K:
1451 case BPF_ALU64 | BPF_ARSH | BPF_K:
1452 emit(A64_ASR(is64, dst, dst, imm), ctx);
1453 break;
1454
1455 /* JUMP off */
1456 case BPF_JMP | BPF_JA:
1457 case BPF_JMP32 | BPF_JA:
1458 if (BPF_CLASS(code) == BPF_JMP)
1459 jmp_offset = bpf2a64_offset(i, off, ctx);
1460 else
1461 jmp_offset = bpf2a64_offset(i, imm, ctx);
1462 check_imm26(jmp_offset);
1463 emit(A64_B(jmp_offset), ctx);
1464 break;
1465 /* IF (dst COND src) JUMP off */
1466 case BPF_JMP | BPF_JEQ | BPF_X:
1467 case BPF_JMP | BPF_JGT | BPF_X:
1468 case BPF_JMP | BPF_JLT | BPF_X:
1469 case BPF_JMP | BPF_JGE | BPF_X:
1470 case BPF_JMP | BPF_JLE | BPF_X:
1471 case BPF_JMP | BPF_JNE | BPF_X:
1472 case BPF_JMP | BPF_JSGT | BPF_X:
1473 case BPF_JMP | BPF_JSLT | BPF_X:
1474 case BPF_JMP | BPF_JSGE | BPF_X:
1475 case BPF_JMP | BPF_JSLE | BPF_X:
1476 case BPF_JMP32 | BPF_JEQ | BPF_X:
1477 case BPF_JMP32 | BPF_JGT | BPF_X:
1478 case BPF_JMP32 | BPF_JLT | BPF_X:
1479 case BPF_JMP32 | BPF_JGE | BPF_X:
1480 case BPF_JMP32 | BPF_JLE | BPF_X:
1481 case BPF_JMP32 | BPF_JNE | BPF_X:
1482 case BPF_JMP32 | BPF_JSGT | BPF_X:
1483 case BPF_JMP32 | BPF_JSLT | BPF_X:
1484 case BPF_JMP32 | BPF_JSGE | BPF_X:
1485 case BPF_JMP32 | BPF_JSLE | BPF_X:
1486 emit(A64_CMP(is64, dst, src), ctx);
1487 emit_cond_jmp:
1488 jmp_offset = bpf2a64_offset(i, off, ctx);
1489 check_imm19(jmp_offset);
1490 switch (BPF_OP(code)) {
1491 case BPF_JEQ:
1492 jmp_cond = A64_COND_EQ;
1493 break;
1494 case BPF_JGT:
1495 jmp_cond = A64_COND_HI;
1496 break;
1497 case BPF_JLT:
1498 jmp_cond = A64_COND_CC;
1499 break;
1500 case BPF_JGE:
1501 jmp_cond = A64_COND_CS;
1502 break;
1503 case BPF_JLE:
1504 jmp_cond = A64_COND_LS;
1505 break;
1506 case BPF_JSET:
1507 case BPF_JNE:
1508 jmp_cond = A64_COND_NE;
1509 break;
1510 case BPF_JSGT:
1511 jmp_cond = A64_COND_GT;
1512 break;
1513 case BPF_JSLT:
1514 jmp_cond = A64_COND_LT;
1515 break;
1516 case BPF_JSGE:
1517 jmp_cond = A64_COND_GE;
1518 break;
1519 case BPF_JSLE:
1520 jmp_cond = A64_COND_LE;
1521 break;
1522 default:
1523 return -EFAULT;
1524 }
1525 emit(A64_B_(jmp_cond, jmp_offset), ctx);
1526 break;
1527 case BPF_JMP | BPF_JSET | BPF_X:
1528 case BPF_JMP32 | BPF_JSET | BPF_X:
1529 emit(A64_TST(is64, dst, src), ctx);
1530 goto emit_cond_jmp;
1531 /* IF (dst COND imm) JUMP off */
1532 case BPF_JMP | BPF_JEQ | BPF_K:
1533 case BPF_JMP | BPF_JGT | BPF_K:
1534 case BPF_JMP | BPF_JLT | BPF_K:
1535 case BPF_JMP | BPF_JGE | BPF_K:
1536 case BPF_JMP | BPF_JLE | BPF_K:
1537 case BPF_JMP | BPF_JNE | BPF_K:
1538 case BPF_JMP | BPF_JSGT | BPF_K:
1539 case BPF_JMP | BPF_JSLT | BPF_K:
1540 case BPF_JMP | BPF_JSGE | BPF_K:
1541 case BPF_JMP | BPF_JSLE | BPF_K:
1542 case BPF_JMP32 | BPF_JEQ | BPF_K:
1543 case BPF_JMP32 | BPF_JGT | BPF_K:
1544 case BPF_JMP32 | BPF_JLT | BPF_K:
1545 case BPF_JMP32 | BPF_JGE | BPF_K:
1546 case BPF_JMP32 | BPF_JLE | BPF_K:
1547 case BPF_JMP32 | BPF_JNE | BPF_K:
1548 case BPF_JMP32 | BPF_JSGT | BPF_K:
1549 case BPF_JMP32 | BPF_JSLT | BPF_K:
1550 case BPF_JMP32 | BPF_JSGE | BPF_K:
1551 case BPF_JMP32 | BPF_JSLE | BPF_K:
1552 if (is_addsub_imm(imm)) {
1553 emit(A64_CMP_I(is64, dst, imm), ctx);
1554 } else if (is_addsub_imm(-(u32)imm)) {
1555 emit(A64_CMN_I(is64, dst, -imm), ctx);
1556 } else {
1557 emit_a64_mov_i(is64, tmp, imm, ctx);
1558 emit(A64_CMP(is64, dst, tmp), ctx);
1559 }
1560 goto emit_cond_jmp;
1561 case BPF_JMP | BPF_JSET | BPF_K:
1562 case BPF_JMP32 | BPF_JSET | BPF_K:
1563 a64_insn = A64_TST_I(is64, dst, imm);
1564 if (a64_insn != AARCH64_BREAK_FAULT) {
1565 emit(a64_insn, ctx);
1566 } else {
1567 emit_a64_mov_i(is64, tmp, imm, ctx);
1568 emit(A64_TST(is64, dst, tmp), ctx);
1569 }
1570 goto emit_cond_jmp;
1571 /* function call */
1572 case BPF_JMP | BPF_CALL:
1573 {
1574 const u8 r0 = bpf2a64[BPF_REG_0];
1575 bool func_addr_fixed;
1576 u64 func_addr;
1577 u32 cpu_offset;
1578
1579 /* Implement helper call to bpf_get_smp_processor_id() inline */
1580 if (insn->src_reg == 0 && insn->imm == BPF_FUNC_get_smp_processor_id) {
1581 cpu_offset = offsetof(struct thread_info, cpu);
1582
1583 emit(A64_MRS_SP_EL0(tmp), ctx);
1584 if (is_lsi_offset(cpu_offset, 2)) {
1585 emit(A64_LDR32I(r0, tmp, cpu_offset), ctx);
1586 } else {
1587 emit_a64_mov_i(1, tmp2, cpu_offset, ctx);
1588 emit(A64_LDR32(r0, tmp, tmp2), ctx);
1589 }
1590 break;
1591 }
1592
1593 /* Implement helper call to bpf_get_current_task/_btf() inline */
1594 if (insn->src_reg == 0 && (insn->imm == BPF_FUNC_get_current_task ||
1595 insn->imm == BPF_FUNC_get_current_task_btf)) {
1596 emit(A64_MRS_SP_EL0(r0), ctx);
1597 break;
1598 }
1599
1600 ret = bpf_jit_get_func_addr(ctx->prog, insn, extra_pass,
1601 &func_addr, &func_addr_fixed);
1602 if (ret < 0)
1603 return ret;
1604 emit_call(func_addr, ctx);
1605 /*
1606 * Call to arch_bpf_timed_may_goto() is emitted by the
1607 * verifier and called with custom calling convention with
1608 * first argument and return value in BPF_REG_AX (x9).
1609 */
1610 if (func_addr != (u64)arch_bpf_timed_may_goto)
1611 emit(A64_MOV(1, r0, A64_R(0)), ctx);
1612 break;
1613 }
1614 /* tail call */
1615 case BPF_JMP | BPF_TAIL_CALL:
1616 if (emit_bpf_tail_call(ctx))
1617 return -EFAULT;
1618 break;
1619 /* function return */
1620 case BPF_JMP | BPF_EXIT:
1621 /* Optimization: when last instruction is EXIT,
1622 simply fallthrough to epilogue. */
1623 if (i == ctx->prog->len - 1)
1624 break;
1625 jmp_offset = epilogue_offset(ctx);
1626 check_imm26(jmp_offset);
1627 emit(A64_B(jmp_offset), ctx);
1628 break;
1629
1630 /* dst = imm64 */
1631 case BPF_LD | BPF_IMM | BPF_DW:
1632 {
1633 const struct bpf_insn insn1 = insn[1];
1634 u64 imm64;
1635
1636 imm64 = (u64)insn1.imm << 32 | (u32)imm;
1637 if (bpf_pseudo_func(insn))
1638 emit_addr_mov_i64(dst, imm64, ctx);
1639 else
1640 emit_a64_mov_i64(dst, imm64, ctx);
1641
1642 return 1;
1643 }
1644
1645 /* LDX: dst = (u64)*(unsigned size *)(src + off) */
1646 case BPF_LDX | BPF_MEM | BPF_W:
1647 case BPF_LDX | BPF_MEM | BPF_H:
1648 case BPF_LDX | BPF_MEM | BPF_B:
1649 case BPF_LDX | BPF_MEM | BPF_DW:
1650 case BPF_LDX | BPF_PROBE_MEM | BPF_DW:
1651 case BPF_LDX | BPF_PROBE_MEM | BPF_W:
1652 case BPF_LDX | BPF_PROBE_MEM | BPF_H:
1653 case BPF_LDX | BPF_PROBE_MEM | BPF_B:
1654 /* LDXS: dst_reg = (s64)*(signed size *)(src_reg + off) */
1655 case BPF_LDX | BPF_MEMSX | BPF_B:
1656 case BPF_LDX | BPF_MEMSX | BPF_H:
1657 case BPF_LDX | BPF_MEMSX | BPF_W:
1658 case BPF_LDX | BPF_PROBE_MEMSX | BPF_B:
1659 case BPF_LDX | BPF_PROBE_MEMSX | BPF_H:
1660 case BPF_LDX | BPF_PROBE_MEMSX | BPF_W:
1661 case BPF_LDX | BPF_PROBE_MEM32 | BPF_B:
1662 case BPF_LDX | BPF_PROBE_MEM32 | BPF_H:
1663 case BPF_LDX | BPF_PROBE_MEM32 | BPF_W:
1664 case BPF_LDX | BPF_PROBE_MEM32 | BPF_DW:
1665 case BPF_LDX | BPF_PROBE_MEM32SX | BPF_B:
1666 case BPF_LDX | BPF_PROBE_MEM32SX | BPF_H:
1667 case BPF_LDX | BPF_PROBE_MEM32SX | BPF_W:
1668 if (BPF_MODE(insn->code) == BPF_PROBE_MEM32 ||
1669 BPF_MODE(insn->code) == BPF_PROBE_MEM32SX) {
1670 emit(A64_ADD(1, tmp2, src, arena_vm_base), ctx);
1671 src = tmp2;
1672 }
1673 if (src == fp) {
1674 src_adj = ctx->priv_sp_used ? priv_sp : A64_SP;
1675 off_adj = off + ctx->stack_size;
1676 } else {
1677 src_adj = src;
1678 off_adj = off;
1679 }
1680 sign_extend = (BPF_MODE(insn->code) == BPF_MEMSX ||
1681 BPF_MODE(insn->code) == BPF_PROBE_MEMSX ||
1682 BPF_MODE(insn->code) == BPF_PROBE_MEM32SX);
1683 switch (BPF_SIZE(code)) {
1684 case BPF_W:
1685 if (is_lsi_offset(off_adj, 2)) {
1686 if (sign_extend)
1687 emit(A64_LDRSWI(dst, src_adj, off_adj), ctx);
1688 else
1689 emit(A64_LDR32I(dst, src_adj, off_adj), ctx);
1690 } else {
1691 emit_a64_mov_i(1, tmp, off, ctx);
1692 if (sign_extend)
1693 emit(A64_LDRSW(dst, src, tmp), ctx);
1694 else
1695 emit(A64_LDR32(dst, src, tmp), ctx);
1696 }
1697 break;
1698 case BPF_H:
1699 if (is_lsi_offset(off_adj, 1)) {
1700 if (sign_extend)
1701 emit(A64_LDRSHI(dst, src_adj, off_adj), ctx);
1702 else
1703 emit(A64_LDRHI(dst, src_adj, off_adj), ctx);
1704 } else {
1705 emit_a64_mov_i(1, tmp, off, ctx);
1706 if (sign_extend)
1707 emit(A64_LDRSH(dst, src, tmp), ctx);
1708 else
1709 emit(A64_LDRH(dst, src, tmp), ctx);
1710 }
1711 break;
1712 case BPF_B:
1713 if (is_lsi_offset(off_adj, 0)) {
1714 if (sign_extend)
1715 emit(A64_LDRSBI(dst, src_adj, off_adj), ctx);
1716 else
1717 emit(A64_LDRBI(dst, src_adj, off_adj), ctx);
1718 } else {
1719 emit_a64_mov_i(1, tmp, off, ctx);
1720 if (sign_extend)
1721 emit(A64_LDRSB(dst, src, tmp), ctx);
1722 else
1723 emit(A64_LDRB(dst, src, tmp), ctx);
1724 }
1725 break;
1726 case BPF_DW:
1727 if (is_lsi_offset(off_adj, 3)) {
1728 emit(A64_LDR64I(dst, src_adj, off_adj), ctx);
1729 } else {
1730 emit_a64_mov_i(1, tmp, off, ctx);
1731 emit(A64_LDR64(dst, src, tmp), ctx);
1732 }
1733 break;
1734 }
1735
1736 ret = add_exception_handler(insn, ctx, dst);
1737 if (ret)
1738 return ret;
1739 break;
1740
1741 /* speculation barrier against v1 and v4 */
1742 case BPF_ST | BPF_NOSPEC:
1743 if (alternative_has_cap_likely(ARM64_HAS_SB)) {
1744 emit(A64_SB, ctx);
1745 } else {
1746 emit(A64_DSB_NSH, ctx);
1747 emit(A64_ISB, ctx);
1748 }
1749 break;
1750
1751 /* ST: *(size *)(dst + off) = imm */
1752 case BPF_ST | BPF_MEM | BPF_W:
1753 case BPF_ST | BPF_MEM | BPF_H:
1754 case BPF_ST | BPF_MEM | BPF_B:
1755 case BPF_ST | BPF_MEM | BPF_DW:
1756 case BPF_ST | BPF_PROBE_MEM32 | BPF_B:
1757 case BPF_ST | BPF_PROBE_MEM32 | BPF_H:
1758 case BPF_ST | BPF_PROBE_MEM32 | BPF_W:
1759 case BPF_ST | BPF_PROBE_MEM32 | BPF_DW:
1760 if (BPF_MODE(insn->code) == BPF_PROBE_MEM32) {
1761 emit(A64_ADD(1, tmp3, dst, arena_vm_base), ctx);
1762 dst = tmp3;
1763 }
1764 if (dst == fp) {
1765 dst_adj = ctx->priv_sp_used ? priv_sp : A64_SP;
1766 off_adj = off + ctx->stack_size;
1767 } else {
1768 dst_adj = dst;
1769 off_adj = off;
1770 }
1771 /* Load imm to a register then store it */
1772 emit_a64_mov_i(1, tmp, imm, ctx);
1773 switch (BPF_SIZE(code)) {
1774 case BPF_W:
1775 if (is_lsi_offset(off_adj, 2)) {
1776 emit(A64_STR32I(tmp, dst_adj, off_adj), ctx);
1777 } else {
1778 emit_a64_mov_i(1, tmp2, off, ctx);
1779 emit(A64_STR32(tmp, dst, tmp2), ctx);
1780 }
1781 break;
1782 case BPF_H:
1783 if (is_lsi_offset(off_adj, 1)) {
1784 emit(A64_STRHI(tmp, dst_adj, off_adj), ctx);
1785 } else {
1786 emit_a64_mov_i(1, tmp2, off, ctx);
1787 emit(A64_STRH(tmp, dst, tmp2), ctx);
1788 }
1789 break;
1790 case BPF_B:
1791 if (is_lsi_offset(off_adj, 0)) {
1792 emit(A64_STRBI(tmp, dst_adj, off_adj), ctx);
1793 } else {
1794 emit_a64_mov_i(1, tmp2, off, ctx);
1795 emit(A64_STRB(tmp, dst, tmp2), ctx);
1796 }
1797 break;
1798 case BPF_DW:
1799 if (is_lsi_offset(off_adj, 3)) {
1800 emit(A64_STR64I(tmp, dst_adj, off_adj), ctx);
1801 } else {
1802 emit_a64_mov_i(1, tmp2, off, ctx);
1803 emit(A64_STR64(tmp, dst, tmp2), ctx);
1804 }
1805 break;
1806 }
1807
1808 ret = add_exception_handler(insn, ctx, dst);
1809 if (ret)
1810 return ret;
1811 break;
1812
1813 /* STX: *(size *)(dst + off) = src */
1814 case BPF_STX | BPF_MEM | BPF_W:
1815 case BPF_STX | BPF_MEM | BPF_H:
1816 case BPF_STX | BPF_MEM | BPF_B:
1817 case BPF_STX | BPF_MEM | BPF_DW:
1818 case BPF_STX | BPF_PROBE_MEM32 | BPF_B:
1819 case BPF_STX | BPF_PROBE_MEM32 | BPF_H:
1820 case BPF_STX | BPF_PROBE_MEM32 | BPF_W:
1821 case BPF_STX | BPF_PROBE_MEM32 | BPF_DW:
1822 if (BPF_MODE(insn->code) == BPF_PROBE_MEM32) {
1823 emit(A64_ADD(1, tmp2, dst, arena_vm_base), ctx);
1824 dst = tmp2;
1825 }
1826 if (dst == fp) {
1827 dst_adj = ctx->priv_sp_used ? priv_sp : A64_SP;
1828 off_adj = off + ctx->stack_size;
1829 } else {
1830 dst_adj = dst;
1831 off_adj = off;
1832 }
1833 switch (BPF_SIZE(code)) {
1834 case BPF_W:
1835 if (is_lsi_offset(off_adj, 2)) {
1836 emit(A64_STR32I(src, dst_adj, off_adj), ctx);
1837 } else {
1838 emit_a64_mov_i(1, tmp, off, ctx);
1839 emit(A64_STR32(src, dst, tmp), ctx);
1840 }
1841 break;
1842 case BPF_H:
1843 if (is_lsi_offset(off_adj, 1)) {
1844 emit(A64_STRHI(src, dst_adj, off_adj), ctx);
1845 } else {
1846 emit_a64_mov_i(1, tmp, off, ctx);
1847 emit(A64_STRH(src, dst, tmp), ctx);
1848 }
1849 break;
1850 case BPF_B:
1851 if (is_lsi_offset(off_adj, 0)) {
1852 emit(A64_STRBI(src, dst_adj, off_adj), ctx);
1853 } else {
1854 emit_a64_mov_i(1, tmp, off, ctx);
1855 emit(A64_STRB(src, dst, tmp), ctx);
1856 }
1857 break;
1858 case BPF_DW:
1859 if (is_lsi_offset(off_adj, 3)) {
1860 emit(A64_STR64I(src, dst_adj, off_adj), ctx);
1861 } else {
1862 emit_a64_mov_i(1, tmp, off, ctx);
1863 emit(A64_STR64(src, dst, tmp), ctx);
1864 }
1865 break;
1866 }
1867
1868 ret = add_exception_handler(insn, ctx, dst);
1869 if (ret)
1870 return ret;
1871 break;
1872
1873 case BPF_STX | BPF_ATOMIC | BPF_B:
1874 case BPF_STX | BPF_ATOMIC | BPF_H:
1875 case BPF_STX | BPF_ATOMIC | BPF_W:
1876 case BPF_STX | BPF_ATOMIC | BPF_DW:
1877 case BPF_STX | BPF_PROBE_ATOMIC | BPF_B:
1878 case BPF_STX | BPF_PROBE_ATOMIC | BPF_H:
1879 case BPF_STX | BPF_PROBE_ATOMIC | BPF_W:
1880 case BPF_STX | BPF_PROBE_ATOMIC | BPF_DW:
1881 if (bpf_atomic_is_load_store(insn))
1882 ret = emit_atomic_ld_st(insn, ctx);
1883 else if (cpus_have_cap(ARM64_HAS_LSE_ATOMICS))
1884 ret = emit_lse_atomic(insn, ctx);
1885 else
1886 ret = emit_ll_sc_atomic(insn, ctx);
1887 if (ret)
1888 return ret;
1889
1890 if (BPF_MODE(insn->code) == BPF_PROBE_ATOMIC) {
1891 ret = add_exception_handler(insn, ctx, dst);
1892 if (ret)
1893 return ret;
1894 }
1895 break;
1896
1897 default:
1898 pr_err_once("unknown opcode %02x\n", code);
1899 return -EINVAL;
1900 }
1901
1902 return 0;
1903 }
1904
build_body(struct jit_ctx * ctx,bool extra_pass)1905 static int build_body(struct jit_ctx *ctx, bool extra_pass)
1906 {
1907 const struct bpf_prog *prog = ctx->prog;
1908 int i;
1909
1910 /*
1911 * - offset[0] offset of the end of prologue,
1912 * start of the 1st instruction.
1913 * - offset[1] - offset of the end of 1st instruction,
1914 * start of the 2nd instruction
1915 * [....]
1916 * - offset[3] - offset of the end of 3rd instruction,
1917 * start of 4th instruction
1918 */
1919 for (i = 0; i < prog->len; i++) {
1920 const struct bpf_insn *insn = &prog->insnsi[i];
1921 int ret;
1922
1923 ctx->offset[i] = ctx->idx;
1924 ret = build_insn(insn, ctx, extra_pass);
1925 if (ret > 0) {
1926 i++;
1927 ctx->offset[i] = ctx->idx;
1928 continue;
1929 }
1930 if (ret)
1931 return ret;
1932 }
1933 /*
1934 * offset is allocated with prog->len + 1 so fill in
1935 * the last element with the offset after the last
1936 * instruction (end of program)
1937 */
1938 ctx->offset[i] = ctx->idx;
1939
1940 return 0;
1941 }
1942
validate_code(struct jit_ctx * ctx)1943 static int validate_code(struct jit_ctx *ctx)
1944 {
1945 int i;
1946
1947 for (i = 0; i < ctx->idx; i++) {
1948 u32 a64_insn = le32_to_cpu(ctx->image[i]);
1949
1950 if (a64_insn == AARCH64_BREAK_FAULT)
1951 return -1;
1952 }
1953 return 0;
1954 }
1955
validate_ctx(struct jit_ctx * ctx)1956 static int validate_ctx(struct jit_ctx *ctx)
1957 {
1958 if (validate_code(ctx))
1959 return -1;
1960
1961 if (WARN_ON_ONCE(ctx->exentry_idx != ctx->prog->aux->num_exentries))
1962 return -1;
1963
1964 return 0;
1965 }
1966
bpf_flush_icache(void * start,void * end)1967 static inline void bpf_flush_icache(void *start, void *end)
1968 {
1969 flush_icache_range((unsigned long)start, (unsigned long)end);
1970 }
1971
priv_stack_init_guard(void __percpu * priv_stack_ptr,int alloc_size)1972 static void priv_stack_init_guard(void __percpu *priv_stack_ptr, int alloc_size)
1973 {
1974 int cpu, underflow_idx = (alloc_size - PRIV_STACK_GUARD_SZ) >> 3;
1975 u64 *stack_ptr;
1976
1977 for_each_possible_cpu(cpu) {
1978 stack_ptr = per_cpu_ptr(priv_stack_ptr, cpu);
1979 stack_ptr[0] = PRIV_STACK_GUARD_VAL;
1980 stack_ptr[1] = PRIV_STACK_GUARD_VAL;
1981 stack_ptr[underflow_idx] = PRIV_STACK_GUARD_VAL;
1982 stack_ptr[underflow_idx + 1] = PRIV_STACK_GUARD_VAL;
1983 }
1984 }
1985
priv_stack_check_guard(void __percpu * priv_stack_ptr,int alloc_size,struct bpf_prog * prog)1986 static void priv_stack_check_guard(void __percpu *priv_stack_ptr, int alloc_size,
1987 struct bpf_prog *prog)
1988 {
1989 int cpu, underflow_idx = (alloc_size - PRIV_STACK_GUARD_SZ) >> 3;
1990 u64 *stack_ptr;
1991
1992 for_each_possible_cpu(cpu) {
1993 stack_ptr = per_cpu_ptr(priv_stack_ptr, cpu);
1994 if (stack_ptr[0] != PRIV_STACK_GUARD_VAL ||
1995 stack_ptr[1] != PRIV_STACK_GUARD_VAL ||
1996 stack_ptr[underflow_idx] != PRIV_STACK_GUARD_VAL ||
1997 stack_ptr[underflow_idx + 1] != PRIV_STACK_GUARD_VAL) {
1998 pr_err("BPF private stack overflow/underflow detected for prog %sx\n",
1999 bpf_jit_get_prog_name(prog));
2000 break;
2001 }
2002 }
2003 }
2004
2005 struct arm64_jit_data {
2006 struct bpf_binary_header *header;
2007 u8 *ro_image;
2008 struct bpf_binary_header *ro_header;
2009 struct jit_ctx ctx;
2010 };
2011
bpf_int_jit_compile(struct bpf_prog * prog)2012 struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
2013 {
2014 int image_size, prog_size, extable_size, extable_align, extable_offset;
2015 struct bpf_prog *tmp, *orig_prog = prog;
2016 struct bpf_binary_header *header;
2017 struct bpf_binary_header *ro_header = NULL;
2018 struct arm64_jit_data *jit_data;
2019 void __percpu *priv_stack_ptr = NULL;
2020 bool was_classic = bpf_prog_was_classic(prog);
2021 int priv_stack_alloc_sz;
2022 bool tmp_blinded = false;
2023 bool extra_pass = false;
2024 struct jit_ctx ctx;
2025 u8 *image_ptr;
2026 u8 *ro_image_ptr;
2027 int body_idx;
2028 int exentry_idx;
2029
2030 if (!prog->jit_requested)
2031 return orig_prog;
2032
2033 tmp = bpf_jit_blind_constants(prog);
2034 /* If blinding was requested and we failed during blinding,
2035 * we must fall back to the interpreter.
2036 */
2037 if (IS_ERR(tmp))
2038 return orig_prog;
2039 if (tmp != prog) {
2040 tmp_blinded = true;
2041 prog = tmp;
2042 }
2043
2044 jit_data = prog->aux->jit_data;
2045 if (!jit_data) {
2046 jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
2047 if (!jit_data) {
2048 prog = orig_prog;
2049 goto out;
2050 }
2051 prog->aux->jit_data = jit_data;
2052 }
2053 priv_stack_ptr = prog->aux->priv_stack_ptr;
2054 if (!priv_stack_ptr && prog->aux->jits_use_priv_stack) {
2055 /* Allocate actual private stack size with verifier-calculated
2056 * stack size plus two memory guards to protect overflow and
2057 * underflow.
2058 */
2059 priv_stack_alloc_sz = round_up(prog->aux->stack_depth, 16) +
2060 2 * PRIV_STACK_GUARD_SZ;
2061 priv_stack_ptr = __alloc_percpu_gfp(priv_stack_alloc_sz, 16, GFP_KERNEL);
2062 if (!priv_stack_ptr) {
2063 prog = orig_prog;
2064 goto out_priv_stack;
2065 }
2066
2067 priv_stack_init_guard(priv_stack_ptr, priv_stack_alloc_sz);
2068 prog->aux->priv_stack_ptr = priv_stack_ptr;
2069 }
2070 if (jit_data->ctx.offset) {
2071 ctx = jit_data->ctx;
2072 ro_image_ptr = jit_data->ro_image;
2073 ro_header = jit_data->ro_header;
2074 header = jit_data->header;
2075 image_ptr = (void *)header + ((void *)ro_image_ptr
2076 - (void *)ro_header);
2077 extra_pass = true;
2078 prog_size = sizeof(u32) * ctx.idx;
2079 goto skip_init_ctx;
2080 }
2081 memset(&ctx, 0, sizeof(ctx));
2082 ctx.prog = prog;
2083
2084 ctx.offset = kvcalloc(prog->len + 1, sizeof(int), GFP_KERNEL);
2085 if (ctx.offset == NULL) {
2086 prog = orig_prog;
2087 goto out_off;
2088 }
2089
2090 ctx.user_vm_start = bpf_arena_get_user_vm_start(prog->aux->arena);
2091 ctx.arena_vm_start = bpf_arena_get_kern_vm_start(prog->aux->arena);
2092
2093 if (priv_stack_ptr)
2094 ctx.priv_sp_used = true;
2095
2096 /* Pass 1: Estimate the maximum image size.
2097 *
2098 * BPF line info needs ctx->offset[i] to be the offset of
2099 * instruction[i] in jited image, so build prologue first.
2100 */
2101 if (build_prologue(&ctx, was_classic)) {
2102 prog = orig_prog;
2103 goto out_off;
2104 }
2105
2106 if (build_body(&ctx, extra_pass)) {
2107 prog = orig_prog;
2108 goto out_off;
2109 }
2110
2111 ctx.epilogue_offset = ctx.idx;
2112 build_epilogue(&ctx, was_classic);
2113 build_plt(&ctx);
2114
2115 extable_align = __alignof__(struct exception_table_entry);
2116 extable_size = prog->aux->num_exentries *
2117 sizeof(struct exception_table_entry);
2118
2119 /* Now we know the maximum image size. */
2120 prog_size = sizeof(u32) * ctx.idx;
2121 /* also allocate space for plt target */
2122 extable_offset = round_up(prog_size + PLT_TARGET_SIZE, extable_align);
2123 image_size = extable_offset + extable_size;
2124 ro_header = bpf_jit_binary_pack_alloc(image_size, &ro_image_ptr,
2125 sizeof(u32), &header, &image_ptr,
2126 jit_fill_hole);
2127 if (!ro_header) {
2128 prog = orig_prog;
2129 goto out_off;
2130 }
2131
2132 /* Pass 2: Determine jited position and result for each instruction */
2133
2134 /*
2135 * Use the image(RW) for writing the JITed instructions. But also save
2136 * the ro_image(RX) for calculating the offsets in the image. The RW
2137 * image will be later copied to the RX image from where the program
2138 * will run. The bpf_jit_binary_pack_finalize() will do this copy in the
2139 * final step.
2140 */
2141 ctx.image = (__le32 *)image_ptr;
2142 ctx.ro_image = (__le32 *)ro_image_ptr;
2143 if (extable_size)
2144 prog->aux->extable = (void *)ro_image_ptr + extable_offset;
2145 skip_init_ctx:
2146 ctx.idx = 0;
2147 ctx.exentry_idx = 0;
2148 ctx.write = true;
2149
2150 build_prologue(&ctx, was_classic);
2151
2152 /* Record exentry_idx and body_idx before first build_body */
2153 exentry_idx = ctx.exentry_idx;
2154 body_idx = ctx.idx;
2155 /* Dont write body instructions to memory for now */
2156 ctx.write = false;
2157
2158 if (build_body(&ctx, extra_pass)) {
2159 prog = orig_prog;
2160 goto out_free_hdr;
2161 }
2162
2163 ctx.epilogue_offset = ctx.idx;
2164 ctx.exentry_idx = exentry_idx;
2165 ctx.idx = body_idx;
2166 ctx.write = true;
2167
2168 /* Pass 3: Adjust jump offset and write final image */
2169 if (build_body(&ctx, extra_pass) ||
2170 WARN_ON_ONCE(ctx.idx != ctx.epilogue_offset)) {
2171 prog = orig_prog;
2172 goto out_free_hdr;
2173 }
2174
2175 build_epilogue(&ctx, was_classic);
2176 build_plt(&ctx);
2177
2178 /* Extra pass to validate JITed code. */
2179 if (validate_ctx(&ctx)) {
2180 prog = orig_prog;
2181 goto out_free_hdr;
2182 }
2183
2184 /* update the real prog size */
2185 prog_size = sizeof(u32) * ctx.idx;
2186
2187 /* And we're done. */
2188 if (bpf_jit_enable > 1)
2189 bpf_jit_dump(prog->len, prog_size, 2, ctx.image);
2190
2191 if (!prog->is_func || extra_pass) {
2192 /* The jited image may shrink since the jited result for
2193 * BPF_CALL to subprog may be changed from indirect call
2194 * to direct call.
2195 */
2196 if (extra_pass && ctx.idx > jit_data->ctx.idx) {
2197 pr_err_once("multi-func JIT bug %d > %d\n",
2198 ctx.idx, jit_data->ctx.idx);
2199 prog->bpf_func = NULL;
2200 prog->jited = 0;
2201 prog->jited_len = 0;
2202 goto out_free_hdr;
2203 }
2204 if (WARN_ON(bpf_jit_binary_pack_finalize(ro_header, header))) {
2205 /* ro_header has been freed */
2206 ro_header = NULL;
2207 prog = orig_prog;
2208 goto out_off;
2209 }
2210 /*
2211 * The instructions have now been copied to the ROX region from
2212 * where they will execute. Now the data cache has to be cleaned to
2213 * the PoU and the I-cache has to be invalidated for the VAs.
2214 */
2215 bpf_flush_icache(ro_header, ctx.ro_image + ctx.idx);
2216 } else {
2217 jit_data->ctx = ctx;
2218 jit_data->ro_image = ro_image_ptr;
2219 jit_data->header = header;
2220 jit_data->ro_header = ro_header;
2221 }
2222
2223 prog->bpf_func = (void *)ctx.ro_image + cfi_get_offset();
2224 prog->jited = 1;
2225 prog->jited_len = prog_size - cfi_get_offset();
2226
2227 if (!prog->is_func || extra_pass) {
2228 int i;
2229
2230 /* offset[prog->len] is the size of program */
2231 for (i = 0; i <= prog->len; i++)
2232 ctx.offset[i] *= AARCH64_INSN_SIZE;
2233 bpf_prog_fill_jited_linfo(prog, ctx.offset + 1);
2234 out_off:
2235 if (!ro_header && priv_stack_ptr) {
2236 free_percpu(priv_stack_ptr);
2237 prog->aux->priv_stack_ptr = NULL;
2238 }
2239 kvfree(ctx.offset);
2240 out_priv_stack:
2241 kfree(jit_data);
2242 prog->aux->jit_data = NULL;
2243 }
2244 out:
2245 if (tmp_blinded)
2246 bpf_jit_prog_release_other(prog, prog == orig_prog ?
2247 tmp : orig_prog);
2248 return prog;
2249
2250 out_free_hdr:
2251 if (header) {
2252 bpf_arch_text_copy(&ro_header->size, &header->size,
2253 sizeof(header->size));
2254 bpf_jit_binary_pack_free(ro_header, header);
2255 }
2256 goto out_off;
2257 }
2258
bpf_jit_supports_private_stack(void)2259 bool bpf_jit_supports_private_stack(void)
2260 {
2261 return true;
2262 }
2263
bpf_jit_supports_kfunc_call(void)2264 bool bpf_jit_supports_kfunc_call(void)
2265 {
2266 return true;
2267 }
2268
bpf_arch_text_copy(void * dst,void * src,size_t len)2269 void *bpf_arch_text_copy(void *dst, void *src, size_t len)
2270 {
2271 if (!aarch64_insn_copy(dst, src, len))
2272 return ERR_PTR(-EINVAL);
2273 return dst;
2274 }
2275
bpf_jit_alloc_exec_limit(void)2276 u64 bpf_jit_alloc_exec_limit(void)
2277 {
2278 return VMALLOC_END - VMALLOC_START;
2279 }
2280
2281 /* Indicate the JIT backend supports mixing bpf2bpf and tailcalls. */
bpf_jit_supports_subprog_tailcalls(void)2282 bool bpf_jit_supports_subprog_tailcalls(void)
2283 {
2284 return true;
2285 }
2286
invoke_bpf_prog(struct jit_ctx * ctx,struct bpf_tramp_link * l,int bargs_off,int retval_off,int run_ctx_off,bool save_ret)2287 static void invoke_bpf_prog(struct jit_ctx *ctx, struct bpf_tramp_link *l,
2288 int bargs_off, int retval_off, int run_ctx_off,
2289 bool save_ret)
2290 {
2291 __le32 *branch;
2292 u64 enter_prog;
2293 u64 exit_prog;
2294 struct bpf_prog *p = l->link.prog;
2295 int cookie_off = offsetof(struct bpf_tramp_run_ctx, bpf_cookie);
2296
2297 enter_prog = (u64)bpf_trampoline_enter(p);
2298 exit_prog = (u64)bpf_trampoline_exit(p);
2299
2300 if (l->cookie == 0) {
2301 /* if cookie is zero, one instruction is enough to store it */
2302 emit(A64_STR64I(A64_ZR, A64_SP, run_ctx_off + cookie_off), ctx);
2303 } else {
2304 emit_a64_mov_i64(A64_R(10), l->cookie, ctx);
2305 emit(A64_STR64I(A64_R(10), A64_SP, run_ctx_off + cookie_off),
2306 ctx);
2307 }
2308
2309 /* save p to callee saved register x19 to avoid loading p with mov_i64
2310 * each time.
2311 */
2312 emit_addr_mov_i64(A64_R(19), (const u64)p, ctx);
2313
2314 /* arg1: prog */
2315 emit(A64_MOV(1, A64_R(0), A64_R(19)), ctx);
2316 /* arg2: &run_ctx */
2317 emit(A64_ADD_I(1, A64_R(1), A64_SP, run_ctx_off), ctx);
2318
2319 emit_call(enter_prog, ctx);
2320
2321 /* save return value to callee saved register x20 */
2322 emit(A64_MOV(1, A64_R(20), A64_R(0)), ctx);
2323
2324 /* if (__bpf_prog_enter(prog) == 0)
2325 * goto skip_exec_of_prog;
2326 */
2327 branch = ctx->image + ctx->idx;
2328 emit(A64_NOP, ctx);
2329
2330 emit(A64_ADD_I(1, A64_R(0), A64_SP, bargs_off), ctx);
2331 if (!p->jited)
2332 emit_addr_mov_i64(A64_R(1), (const u64)p->insnsi, ctx);
2333
2334 emit_call((const u64)p->bpf_func, ctx);
2335
2336 if (save_ret)
2337 emit(A64_STR64I(A64_R(0), A64_SP, retval_off), ctx);
2338
2339 if (ctx->image) {
2340 int offset = &ctx->image[ctx->idx] - branch;
2341 *branch = cpu_to_le32(A64_CBZ(1, A64_R(0), offset));
2342 }
2343
2344 /* arg1: prog */
2345 emit(A64_MOV(1, A64_R(0), A64_R(19)), ctx);
2346 /* arg2: start time */
2347 emit(A64_MOV(1, A64_R(1), A64_R(20)), ctx);
2348 /* arg3: &run_ctx */
2349 emit(A64_ADD_I(1, A64_R(2), A64_SP, run_ctx_off), ctx);
2350
2351 emit_call(exit_prog, ctx);
2352 }
2353
invoke_bpf_mod_ret(struct jit_ctx * ctx,struct bpf_tramp_links * tl,int bargs_off,int retval_off,int run_ctx_off,__le32 ** branches)2354 static void invoke_bpf_mod_ret(struct jit_ctx *ctx, struct bpf_tramp_links *tl,
2355 int bargs_off, int retval_off, int run_ctx_off,
2356 __le32 **branches)
2357 {
2358 int i;
2359
2360 /* The first fmod_ret program will receive a garbage return value.
2361 * Set this to 0 to avoid confusing the program.
2362 */
2363 emit(A64_STR64I(A64_ZR, A64_SP, retval_off), ctx);
2364 for (i = 0; i < tl->nr_links; i++) {
2365 invoke_bpf_prog(ctx, tl->links[i], bargs_off, retval_off,
2366 run_ctx_off, true);
2367 /* if (*(u64 *)(sp + retval_off) != 0)
2368 * goto do_fexit;
2369 */
2370 emit(A64_LDR64I(A64_R(10), A64_SP, retval_off), ctx);
2371 /* Save the location of branch, and generate a nop.
2372 * This nop will be replaced with a cbnz later.
2373 */
2374 branches[i] = ctx->image + ctx->idx;
2375 emit(A64_NOP, ctx);
2376 }
2377 }
2378
2379 struct arg_aux {
2380 /* how many args are passed through registers, the rest of the args are
2381 * passed through stack
2382 */
2383 int args_in_regs;
2384 /* how many registers are used to pass arguments */
2385 int regs_for_args;
2386 /* how much stack is used for additional args passed to bpf program
2387 * that did not fit in original function registers
2388 */
2389 int bstack_for_args;
2390 /* home much stack is used for additional args passed to the
2391 * original function when called from trampoline (this one needs
2392 * arguments to be properly aligned)
2393 */
2394 int ostack_for_args;
2395 };
2396
calc_arg_aux(const struct btf_func_model * m,struct arg_aux * a)2397 static int calc_arg_aux(const struct btf_func_model *m,
2398 struct arg_aux *a)
2399 {
2400 int stack_slots, nregs, slots, i;
2401
2402 /* verifier ensures m->nr_args <= MAX_BPF_FUNC_ARGS */
2403 for (i = 0, nregs = 0; i < m->nr_args; i++) {
2404 slots = (m->arg_size[i] + 7) / 8;
2405 if (nregs + slots <= 8) /* passed through register ? */
2406 nregs += slots;
2407 else
2408 break;
2409 }
2410
2411 a->args_in_regs = i;
2412 a->regs_for_args = nregs;
2413 a->ostack_for_args = 0;
2414 a->bstack_for_args = 0;
2415
2416 /* the rest arguments are passed through stack */
2417 for (; i < m->nr_args; i++) {
2418 stack_slots = (m->arg_size[i] + 7) / 8;
2419 a->bstack_for_args += stack_slots * 8;
2420 a->ostack_for_args = a->ostack_for_args + stack_slots * 8;
2421 }
2422
2423 return 0;
2424 }
2425
clear_garbage(struct jit_ctx * ctx,int reg,int effective_bytes)2426 static void clear_garbage(struct jit_ctx *ctx, int reg, int effective_bytes)
2427 {
2428 if (effective_bytes) {
2429 int garbage_bits = 64 - 8 * effective_bytes;
2430 #ifdef CONFIG_CPU_BIG_ENDIAN
2431 /* garbage bits are at the right end */
2432 emit(A64_LSR(1, reg, reg, garbage_bits), ctx);
2433 emit(A64_LSL(1, reg, reg, garbage_bits), ctx);
2434 #else
2435 /* garbage bits are at the left end */
2436 emit(A64_LSL(1, reg, reg, garbage_bits), ctx);
2437 emit(A64_LSR(1, reg, reg, garbage_bits), ctx);
2438 #endif
2439 }
2440 }
2441
save_args(struct jit_ctx * ctx,int bargs_off,int oargs_off,const struct btf_func_model * m,const struct arg_aux * a,bool for_call_origin)2442 static void save_args(struct jit_ctx *ctx, int bargs_off, int oargs_off,
2443 const struct btf_func_model *m,
2444 const struct arg_aux *a,
2445 bool for_call_origin)
2446 {
2447 int i;
2448 int reg;
2449 int doff;
2450 int soff;
2451 int slots;
2452 u8 tmp = bpf2a64[TMP_REG_1];
2453
2454 /* store arguments to the stack for the bpf program, or restore
2455 * arguments from stack for the original function
2456 */
2457 for (reg = 0; reg < a->regs_for_args; reg++) {
2458 emit(for_call_origin ?
2459 A64_LDR64I(reg, A64_SP, bargs_off) :
2460 A64_STR64I(reg, A64_SP, bargs_off),
2461 ctx);
2462 bargs_off += 8;
2463 }
2464
2465 soff = 32; /* on stack arguments start from FP + 32 */
2466 doff = (for_call_origin ? oargs_off : bargs_off);
2467
2468 /* save on stack arguments */
2469 for (i = a->args_in_regs; i < m->nr_args; i++) {
2470 slots = (m->arg_size[i] + 7) / 8;
2471 /* verifier ensures arg_size <= 16, so slots equals 1 or 2 */
2472 while (slots-- > 0) {
2473 emit(A64_LDR64I(tmp, A64_FP, soff), ctx);
2474 /* if there is unused space in the last slot, clear
2475 * the garbage contained in the space.
2476 */
2477 if (slots == 0 && !for_call_origin)
2478 clear_garbage(ctx, tmp, m->arg_size[i] % 8);
2479 emit(A64_STR64I(tmp, A64_SP, doff), ctx);
2480 soff += 8;
2481 doff += 8;
2482 }
2483 }
2484 }
2485
restore_args(struct jit_ctx * ctx,int bargs_off,int nregs)2486 static void restore_args(struct jit_ctx *ctx, int bargs_off, int nregs)
2487 {
2488 int reg;
2489
2490 for (reg = 0; reg < nregs; reg++) {
2491 emit(A64_LDR64I(reg, A64_SP, bargs_off), ctx);
2492 bargs_off += 8;
2493 }
2494 }
2495
is_struct_ops_tramp(const struct bpf_tramp_links * fentry_links)2496 static bool is_struct_ops_tramp(const struct bpf_tramp_links *fentry_links)
2497 {
2498 return fentry_links->nr_links == 1 &&
2499 fentry_links->links[0]->link.type == BPF_LINK_TYPE_STRUCT_OPS;
2500 }
2501
2502 /* Based on the x86's implementation of arch_prepare_bpf_trampoline().
2503 *
2504 * bpf prog and function entry before bpf trampoline hooked:
2505 * mov x9, lr
2506 * nop
2507 *
2508 * bpf prog and function entry after bpf trampoline hooked:
2509 * mov x9, lr
2510 * bl <bpf_trampoline or plt>
2511 *
2512 */
prepare_trampoline(struct jit_ctx * ctx,struct bpf_tramp_image * im,struct bpf_tramp_links * tlinks,void * func_addr,const struct btf_func_model * m,const struct arg_aux * a,u32 flags)2513 static int prepare_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im,
2514 struct bpf_tramp_links *tlinks, void *func_addr,
2515 const struct btf_func_model *m,
2516 const struct arg_aux *a,
2517 u32 flags)
2518 {
2519 int i;
2520 int stack_size;
2521 int retaddr_off;
2522 int regs_off;
2523 int retval_off;
2524 int bargs_off;
2525 int nfuncargs_off;
2526 int ip_off;
2527 int run_ctx_off;
2528 int oargs_off;
2529 int nfuncargs;
2530 struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY];
2531 struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT];
2532 struct bpf_tramp_links *fmod_ret = &tlinks[BPF_TRAMP_MODIFY_RETURN];
2533 bool save_ret;
2534 __le32 **branches = NULL;
2535 bool is_struct_ops = is_struct_ops_tramp(fentry);
2536
2537 /* trampoline stack layout:
2538 * [ parent ip ]
2539 * [ FP ]
2540 * SP + retaddr_off [ self ip ]
2541 * [ FP ]
2542 *
2543 * [ padding ] align SP to multiples of 16
2544 *
2545 * [ x20 ] callee saved reg x20
2546 * SP + regs_off [ x19 ] callee saved reg x19
2547 *
2548 * SP + retval_off [ return value ] BPF_TRAMP_F_CALL_ORIG or
2549 * BPF_TRAMP_F_RET_FENTRY_RET
2550 * [ arg reg N ]
2551 * [ ... ]
2552 * SP + bargs_off [ arg reg 1 ] for bpf
2553 *
2554 * SP + nfuncargs_off [ arg regs count ]
2555 *
2556 * SP + ip_off [ traced function ] BPF_TRAMP_F_IP_ARG flag
2557 *
2558 * SP + run_ctx_off [ bpf_tramp_run_ctx ]
2559 *
2560 * [ stack arg N ]
2561 * [ ... ]
2562 * SP + oargs_off [ stack arg 1 ] for original func
2563 */
2564
2565 stack_size = 0;
2566 oargs_off = stack_size;
2567 if (flags & BPF_TRAMP_F_CALL_ORIG)
2568 stack_size += a->ostack_for_args;
2569
2570 run_ctx_off = stack_size;
2571 /* room for bpf_tramp_run_ctx */
2572 stack_size += round_up(sizeof(struct bpf_tramp_run_ctx), 8);
2573
2574 ip_off = stack_size;
2575 /* room for IP address argument */
2576 if (flags & BPF_TRAMP_F_IP_ARG)
2577 stack_size += 8;
2578
2579 nfuncargs_off = stack_size;
2580 /* room for args count */
2581 stack_size += 8;
2582
2583 bargs_off = stack_size;
2584 /* room for args */
2585 nfuncargs = a->regs_for_args + a->bstack_for_args / 8;
2586 stack_size += 8 * nfuncargs;
2587
2588 /* room for return value */
2589 retval_off = stack_size;
2590 save_ret = flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET);
2591 if (save_ret)
2592 stack_size += 8;
2593
2594 /* room for callee saved registers, currently x19 and x20 are used */
2595 regs_off = stack_size;
2596 stack_size += 16;
2597
2598 /* round up to multiples of 16 to avoid SPAlignmentFault */
2599 stack_size = round_up(stack_size, 16);
2600
2601 /* return address locates above FP */
2602 retaddr_off = stack_size + 8;
2603
2604 if (flags & BPF_TRAMP_F_INDIRECT) {
2605 /*
2606 * Indirect call for bpf_struct_ops
2607 */
2608 emit_kcfi(cfi_get_func_hash(func_addr), ctx);
2609 }
2610 /* bpf trampoline may be invoked by 3 instruction types:
2611 * 1. bl, attached to bpf prog or kernel function via short jump
2612 * 2. br, attached to bpf prog or kernel function via long jump
2613 * 3. blr, working as a function pointer, used by struct_ops.
2614 * So BTI_JC should used here to support both br and blr.
2615 */
2616 emit_bti(A64_BTI_JC, ctx);
2617
2618 /* x9 is not set for struct_ops */
2619 if (!is_struct_ops) {
2620 /* frame for parent function */
2621 emit(A64_PUSH(A64_FP, A64_R(9), A64_SP), ctx);
2622 emit(A64_MOV(1, A64_FP, A64_SP), ctx);
2623 }
2624
2625 /* frame for patched function for tracing, or caller for struct_ops */
2626 emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx);
2627 emit(A64_MOV(1, A64_FP, A64_SP), ctx);
2628
2629 /* allocate stack space */
2630 emit(A64_SUB_I(1, A64_SP, A64_SP, stack_size), ctx);
2631
2632 if (flags & BPF_TRAMP_F_IP_ARG) {
2633 /* save ip address of the traced function */
2634 emit_addr_mov_i64(A64_R(10), (const u64)func_addr, ctx);
2635 emit(A64_STR64I(A64_R(10), A64_SP, ip_off), ctx);
2636 }
2637
2638 /* save arg regs count*/
2639 emit(A64_MOVZ(1, A64_R(10), nfuncargs, 0), ctx);
2640 emit(A64_STR64I(A64_R(10), A64_SP, nfuncargs_off), ctx);
2641
2642 /* save args for bpf */
2643 save_args(ctx, bargs_off, oargs_off, m, a, false);
2644
2645 /* save callee saved registers */
2646 emit(A64_STR64I(A64_R(19), A64_SP, regs_off), ctx);
2647 emit(A64_STR64I(A64_R(20), A64_SP, regs_off + 8), ctx);
2648
2649 if (flags & BPF_TRAMP_F_CALL_ORIG) {
2650 /* for the first pass, assume the worst case */
2651 if (!ctx->image)
2652 ctx->idx += 4;
2653 else
2654 emit_a64_mov_i64(A64_R(0), (const u64)im, ctx);
2655 emit_call((const u64)__bpf_tramp_enter, ctx);
2656 }
2657
2658 for (i = 0; i < fentry->nr_links; i++)
2659 invoke_bpf_prog(ctx, fentry->links[i], bargs_off,
2660 retval_off, run_ctx_off,
2661 flags & BPF_TRAMP_F_RET_FENTRY_RET);
2662
2663 if (fmod_ret->nr_links) {
2664 branches = kcalloc(fmod_ret->nr_links, sizeof(__le32 *),
2665 GFP_KERNEL);
2666 if (!branches)
2667 return -ENOMEM;
2668
2669 invoke_bpf_mod_ret(ctx, fmod_ret, bargs_off, retval_off,
2670 run_ctx_off, branches);
2671 }
2672
2673 if (flags & BPF_TRAMP_F_CALL_ORIG) {
2674 /* save args for original func */
2675 save_args(ctx, bargs_off, oargs_off, m, a, true);
2676 /* call original func */
2677 emit(A64_LDR64I(A64_R(10), A64_SP, retaddr_off), ctx);
2678 emit(A64_ADR(A64_LR, AARCH64_INSN_SIZE * 2), ctx);
2679 emit(A64_RET(A64_R(10)), ctx);
2680 /* store return value */
2681 emit(A64_STR64I(A64_R(0), A64_SP, retval_off), ctx);
2682 /* reserve a nop for bpf_tramp_image_put */
2683 im->ip_after_call = ctx->ro_image + ctx->idx;
2684 emit(A64_NOP, ctx);
2685 }
2686
2687 /* update the branches saved in invoke_bpf_mod_ret with cbnz */
2688 for (i = 0; i < fmod_ret->nr_links && ctx->image != NULL; i++) {
2689 int offset = &ctx->image[ctx->idx] - branches[i];
2690 *branches[i] = cpu_to_le32(A64_CBNZ(1, A64_R(10), offset));
2691 }
2692
2693 for (i = 0; i < fexit->nr_links; i++)
2694 invoke_bpf_prog(ctx, fexit->links[i], bargs_off, retval_off,
2695 run_ctx_off, false);
2696
2697 if (flags & BPF_TRAMP_F_CALL_ORIG) {
2698 im->ip_epilogue = ctx->ro_image + ctx->idx;
2699 /* for the first pass, assume the worst case */
2700 if (!ctx->image)
2701 ctx->idx += 4;
2702 else
2703 emit_a64_mov_i64(A64_R(0), (const u64)im, ctx);
2704 emit_call((const u64)__bpf_tramp_exit, ctx);
2705 }
2706
2707 if (flags & BPF_TRAMP_F_RESTORE_REGS)
2708 restore_args(ctx, bargs_off, a->regs_for_args);
2709
2710 /* restore callee saved register x19 and x20 */
2711 emit(A64_LDR64I(A64_R(19), A64_SP, regs_off), ctx);
2712 emit(A64_LDR64I(A64_R(20), A64_SP, regs_off + 8), ctx);
2713
2714 if (save_ret)
2715 emit(A64_LDR64I(A64_R(0), A64_SP, retval_off), ctx);
2716
2717 /* reset SP */
2718 emit(A64_MOV(1, A64_SP, A64_FP), ctx);
2719
2720 if (is_struct_ops) {
2721 emit(A64_POP(A64_FP, A64_LR, A64_SP), ctx);
2722 emit(A64_RET(A64_LR), ctx);
2723 } else {
2724 /* pop frames */
2725 emit(A64_POP(A64_FP, A64_LR, A64_SP), ctx);
2726 emit(A64_POP(A64_FP, A64_R(9), A64_SP), ctx);
2727
2728 if (flags & BPF_TRAMP_F_SKIP_FRAME) {
2729 /* skip patched function, return to parent */
2730 emit(A64_MOV(1, A64_LR, A64_R(9)), ctx);
2731 emit(A64_RET(A64_R(9)), ctx);
2732 } else {
2733 /* return to patched function */
2734 emit(A64_MOV(1, A64_R(10), A64_LR), ctx);
2735 emit(A64_MOV(1, A64_LR, A64_R(9)), ctx);
2736 emit(A64_RET(A64_R(10)), ctx);
2737 }
2738 }
2739
2740 kfree(branches);
2741
2742 return ctx->idx;
2743 }
2744
arch_bpf_trampoline_size(const struct btf_func_model * m,u32 flags,struct bpf_tramp_links * tlinks,void * func_addr)2745 int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags,
2746 struct bpf_tramp_links *tlinks, void *func_addr)
2747 {
2748 struct jit_ctx ctx = {
2749 .image = NULL,
2750 .idx = 0,
2751 };
2752 struct bpf_tramp_image im;
2753 struct arg_aux aaux;
2754 int ret;
2755
2756 ret = calc_arg_aux(m, &aaux);
2757 if (ret < 0)
2758 return ret;
2759
2760 ret = prepare_trampoline(&ctx, &im, tlinks, func_addr, m, &aaux, flags);
2761 if (ret < 0)
2762 return ret;
2763
2764 return ret < 0 ? ret : ret * AARCH64_INSN_SIZE;
2765 }
2766
arch_alloc_bpf_trampoline(unsigned int size)2767 void *arch_alloc_bpf_trampoline(unsigned int size)
2768 {
2769 return bpf_prog_pack_alloc(size, jit_fill_hole);
2770 }
2771
arch_free_bpf_trampoline(void * image,unsigned int size)2772 void arch_free_bpf_trampoline(void *image, unsigned int size)
2773 {
2774 bpf_prog_pack_free(image, size);
2775 }
2776
arch_protect_bpf_trampoline(void * image,unsigned int size)2777 int arch_protect_bpf_trampoline(void *image, unsigned int size)
2778 {
2779 return 0;
2780 }
2781
arch_prepare_bpf_trampoline(struct bpf_tramp_image * im,void * ro_image,void * ro_image_end,const struct btf_func_model * m,u32 flags,struct bpf_tramp_links * tlinks,void * func_addr)2782 int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *ro_image,
2783 void *ro_image_end, const struct btf_func_model *m,
2784 u32 flags, struct bpf_tramp_links *tlinks,
2785 void *func_addr)
2786 {
2787 u32 size = ro_image_end - ro_image;
2788 struct arg_aux aaux;
2789 void *image, *tmp;
2790 int ret;
2791
2792 /* image doesn't need to be in module memory range, so we can
2793 * use kvmalloc.
2794 */
2795 image = kvmalloc(size, GFP_KERNEL);
2796 if (!image)
2797 return -ENOMEM;
2798
2799 struct jit_ctx ctx = {
2800 .image = image,
2801 .ro_image = ro_image,
2802 .idx = 0,
2803 .write = true,
2804 };
2805
2806
2807 jit_fill_hole(image, (unsigned int)(ro_image_end - ro_image));
2808 ret = calc_arg_aux(m, &aaux);
2809 if (ret)
2810 goto out;
2811 ret = prepare_trampoline(&ctx, im, tlinks, func_addr, m, &aaux, flags);
2812
2813 if (ret > 0 && validate_code(&ctx) < 0) {
2814 ret = -EINVAL;
2815 goto out;
2816 }
2817
2818 if (ret > 0)
2819 ret *= AARCH64_INSN_SIZE;
2820
2821 tmp = bpf_arch_text_copy(ro_image, image, size);
2822 if (IS_ERR(tmp)) {
2823 ret = PTR_ERR(tmp);
2824 goto out;
2825 }
2826
2827 out:
2828 kvfree(image);
2829 return ret;
2830 }
2831
is_long_jump(void * ip,void * target)2832 static bool is_long_jump(void *ip, void *target)
2833 {
2834 long offset;
2835
2836 /* NULL target means this is a NOP */
2837 if (!target)
2838 return false;
2839
2840 offset = (long)target - (long)ip;
2841 return offset < -SZ_128M || offset >= SZ_128M;
2842 }
2843
gen_branch_or_nop(enum aarch64_insn_branch_type type,void * ip,void * addr,void * plt,u32 * insn)2844 static int gen_branch_or_nop(enum aarch64_insn_branch_type type, void *ip,
2845 void *addr, void *plt, u32 *insn)
2846 {
2847 void *target;
2848
2849 if (!addr) {
2850 *insn = aarch64_insn_gen_nop();
2851 return 0;
2852 }
2853
2854 if (is_long_jump(ip, addr))
2855 target = plt;
2856 else
2857 target = addr;
2858
2859 *insn = aarch64_insn_gen_branch_imm((unsigned long)ip,
2860 (unsigned long)target,
2861 type);
2862
2863 return *insn != AARCH64_BREAK_FAULT ? 0 : -EFAULT;
2864 }
2865
2866 /* Replace the branch instruction from @ip to @old_addr in a bpf prog or a bpf
2867 * trampoline with the branch instruction from @ip to @new_addr. If @old_addr
2868 * or @new_addr is NULL, the old or new instruction is NOP.
2869 *
2870 * When @ip is the bpf prog entry, a bpf trampoline is being attached or
2871 * detached. Since bpf trampoline and bpf prog are allocated separately with
2872 * vmalloc, the address distance may exceed 128MB, the maximum branch range.
2873 * So long jump should be handled.
2874 *
2875 * When a bpf prog is constructed, a plt pointing to empty trampoline
2876 * dummy_tramp is placed at the end:
2877 *
2878 * bpf_prog:
2879 * mov x9, lr
2880 * nop // patchsite
2881 * ...
2882 * ret
2883 *
2884 * plt:
2885 * ldr x10, target
2886 * br x10
2887 * target:
2888 * .quad dummy_tramp // plt target
2889 *
2890 * This is also the state when no trampoline is attached.
2891 *
2892 * When a short-jump bpf trampoline is attached, the patchsite is patched
2893 * to a bl instruction to the trampoline directly:
2894 *
2895 * bpf_prog:
2896 * mov x9, lr
2897 * bl <short-jump bpf trampoline address> // patchsite
2898 * ...
2899 * ret
2900 *
2901 * plt:
2902 * ldr x10, target
2903 * br x10
2904 * target:
2905 * .quad dummy_tramp // plt target
2906 *
2907 * When a long-jump bpf trampoline is attached, the plt target is filled with
2908 * the trampoline address and the patchsite is patched to a bl instruction to
2909 * the plt:
2910 *
2911 * bpf_prog:
2912 * mov x9, lr
2913 * bl plt // patchsite
2914 * ...
2915 * ret
2916 *
2917 * plt:
2918 * ldr x10, target
2919 * br x10
2920 * target:
2921 * .quad <long-jump bpf trampoline address> // plt target
2922 *
2923 * The dummy_tramp is used to prevent another CPU from jumping to unknown
2924 * locations during the patching process, making the patching process easier.
2925 */
bpf_arch_text_poke(void * ip,enum bpf_text_poke_type poke_type,void * old_addr,void * new_addr)2926 int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type poke_type,
2927 void *old_addr, void *new_addr)
2928 {
2929 int ret;
2930 u32 old_insn;
2931 u32 new_insn;
2932 u32 replaced;
2933 struct bpf_plt *plt = NULL;
2934 unsigned long size = 0UL;
2935 unsigned long offset = ~0UL;
2936 enum aarch64_insn_branch_type branch_type;
2937 char namebuf[KSYM_NAME_LEN];
2938 void *image = NULL;
2939 u64 plt_target = 0ULL;
2940 bool poking_bpf_entry;
2941
2942 if (!__bpf_address_lookup((unsigned long)ip, &size, &offset, namebuf))
2943 /* Only poking bpf text is supported. Since kernel function
2944 * entry is set up by ftrace, we reply on ftrace to poke kernel
2945 * functions.
2946 */
2947 return -ENOTSUPP;
2948
2949 image = ip - offset;
2950 /* zero offset means we're poking bpf prog entry */
2951 poking_bpf_entry = (offset == 0UL);
2952
2953 /* bpf prog entry, find plt and the real patchsite */
2954 if (poking_bpf_entry) {
2955 /* plt locates at the end of bpf prog */
2956 plt = image + size - PLT_TARGET_OFFSET;
2957
2958 /* skip to the nop instruction in bpf prog entry:
2959 * bti c // if BTI enabled
2960 * mov x9, x30
2961 * nop
2962 */
2963 ip = image + POKE_OFFSET * AARCH64_INSN_SIZE;
2964 }
2965
2966 /* long jump is only possible at bpf prog entry */
2967 if (WARN_ON((is_long_jump(ip, new_addr) || is_long_jump(ip, old_addr)) &&
2968 !poking_bpf_entry))
2969 return -EINVAL;
2970
2971 if (poke_type == BPF_MOD_CALL)
2972 branch_type = AARCH64_INSN_BRANCH_LINK;
2973 else
2974 branch_type = AARCH64_INSN_BRANCH_NOLINK;
2975
2976 if (gen_branch_or_nop(branch_type, ip, old_addr, plt, &old_insn) < 0)
2977 return -EFAULT;
2978
2979 if (gen_branch_or_nop(branch_type, ip, new_addr, plt, &new_insn) < 0)
2980 return -EFAULT;
2981
2982 if (is_long_jump(ip, new_addr))
2983 plt_target = (u64)new_addr;
2984 else if (is_long_jump(ip, old_addr))
2985 /* if the old target is a long jump and the new target is not,
2986 * restore the plt target to dummy_tramp, so there is always a
2987 * legal and harmless address stored in plt target, and we'll
2988 * never jump from plt to an unknown place.
2989 */
2990 plt_target = (u64)&dummy_tramp;
2991
2992 if (plt_target) {
2993 /* non-zero plt_target indicates we're patching a bpf prog,
2994 * which is read only.
2995 */
2996 if (set_memory_rw(PAGE_MASK & ((uintptr_t)&plt->target), 1))
2997 return -EFAULT;
2998 WRITE_ONCE(plt->target, plt_target);
2999 set_memory_ro(PAGE_MASK & ((uintptr_t)&plt->target), 1);
3000 /* since plt target points to either the new trampoline
3001 * or dummy_tramp, even if another CPU reads the old plt
3002 * target value before fetching the bl instruction to plt,
3003 * it will be brought back by dummy_tramp, so no barrier is
3004 * required here.
3005 */
3006 }
3007
3008 /* if the old target and the new target are both long jumps, no
3009 * patching is required
3010 */
3011 if (old_insn == new_insn)
3012 return 0;
3013
3014 mutex_lock(&text_mutex);
3015 if (aarch64_insn_read(ip, &replaced)) {
3016 ret = -EFAULT;
3017 goto out;
3018 }
3019
3020 if (replaced != old_insn) {
3021 ret = -EFAULT;
3022 goto out;
3023 }
3024
3025 /* We call aarch64_insn_patch_text_nosync() to replace instruction
3026 * atomically, so no other CPUs will fetch a half-new and half-old
3027 * instruction. But there is chance that another CPU executes the
3028 * old instruction after the patching operation finishes (e.g.,
3029 * pipeline not flushed, or icache not synchronized yet).
3030 *
3031 * 1. when a new trampoline is attached, it is not a problem for
3032 * different CPUs to jump to different trampolines temporarily.
3033 *
3034 * 2. when an old trampoline is freed, we should wait for all other
3035 * CPUs to exit the trampoline and make sure the trampoline is no
3036 * longer reachable, since bpf_tramp_image_put() function already
3037 * uses percpu_ref and task-based rcu to do the sync, no need to call
3038 * the sync version here, see bpf_tramp_image_put() for details.
3039 */
3040 ret = aarch64_insn_patch_text_nosync(ip, new_insn);
3041 out:
3042 mutex_unlock(&text_mutex);
3043
3044 return ret;
3045 }
3046
bpf_jit_supports_ptr_xchg(void)3047 bool bpf_jit_supports_ptr_xchg(void)
3048 {
3049 return true;
3050 }
3051
bpf_jit_supports_exceptions(void)3052 bool bpf_jit_supports_exceptions(void)
3053 {
3054 /* We unwind through both kernel frames starting from within bpf_throw
3055 * call and BPF frames. Therefore we require FP unwinder to be enabled
3056 * to walk kernel frames and reach BPF frames in the stack trace.
3057 * ARM64 kernel is aways compiled with CONFIG_FRAME_POINTER=y
3058 */
3059 return true;
3060 }
3061
bpf_jit_supports_arena(void)3062 bool bpf_jit_supports_arena(void)
3063 {
3064 return true;
3065 }
3066
bpf_jit_supports_insn(struct bpf_insn * insn,bool in_arena)3067 bool bpf_jit_supports_insn(struct bpf_insn *insn, bool in_arena)
3068 {
3069 if (!in_arena)
3070 return true;
3071 switch (insn->code) {
3072 case BPF_STX | BPF_ATOMIC | BPF_W:
3073 case BPF_STX | BPF_ATOMIC | BPF_DW:
3074 if (!bpf_atomic_is_load_store(insn) &&
3075 !cpus_have_cap(ARM64_HAS_LSE_ATOMICS))
3076 return false;
3077 }
3078 return true;
3079 }
3080
bpf_jit_supports_percpu_insn(void)3081 bool bpf_jit_supports_percpu_insn(void)
3082 {
3083 return true;
3084 }
3085
bpf_jit_bypass_spec_v4(void)3086 bool bpf_jit_bypass_spec_v4(void)
3087 {
3088 /* In case of arm64, we rely on the firmware mitigation of Speculative
3089 * Store Bypass as controlled via the ssbd kernel parameter. Whenever
3090 * the mitigation is enabled, it works for all of the kernel code with
3091 * no need to provide any additional instructions. Therefore, skip
3092 * inserting nospec insns against Spectre v4.
3093 */
3094 return true;
3095 }
3096
bpf_jit_supports_timed_may_goto(void)3097 bool bpf_jit_supports_timed_may_goto(void)
3098 {
3099 return true;
3100 }
3101
bpf_jit_inlines_helper_call(s32 imm)3102 bool bpf_jit_inlines_helper_call(s32 imm)
3103 {
3104 switch (imm) {
3105 case BPF_FUNC_get_smp_processor_id:
3106 case BPF_FUNC_get_current_task:
3107 case BPF_FUNC_get_current_task_btf:
3108 return true;
3109 default:
3110 return false;
3111 }
3112 }
3113
bpf_jit_free(struct bpf_prog * prog)3114 void bpf_jit_free(struct bpf_prog *prog)
3115 {
3116 if (prog->jited) {
3117 struct arm64_jit_data *jit_data = prog->aux->jit_data;
3118 struct bpf_binary_header *hdr;
3119 void __percpu *priv_stack_ptr;
3120 int priv_stack_alloc_sz;
3121
3122 /*
3123 * If we fail the final pass of JIT (from jit_subprogs),
3124 * the program may not be finalized yet. Call finalize here
3125 * before freeing it.
3126 */
3127 if (jit_data) {
3128 bpf_jit_binary_pack_finalize(jit_data->ro_header, jit_data->header);
3129 kfree(jit_data);
3130 }
3131 prog->bpf_func -= cfi_get_offset();
3132 hdr = bpf_jit_binary_pack_hdr(prog);
3133 bpf_jit_binary_pack_free(hdr, NULL);
3134 priv_stack_ptr = prog->aux->priv_stack_ptr;
3135 if (priv_stack_ptr) {
3136 priv_stack_alloc_sz = round_up(prog->aux->stack_depth, 16) +
3137 2 * PRIV_STACK_GUARD_SZ;
3138 priv_stack_check_guard(priv_stack_ptr, priv_stack_alloc_sz, prog);
3139 free_percpu(prog->aux->priv_stack_ptr);
3140 }
3141 WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(prog));
3142 }
3143
3144 bpf_prog_unlock_free(prog);
3145 }
3146