// SPDX-License-Identifier: GPL-2.0-only /* * bpf_jit_comp.c: BPF JIT compiler * * Copyright (C) 2011-2013 Eric Dumazet (eric.dumazet@gmail.com) * Internal BPF Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com */ #include #include #include #include #include #include #include #include #include #include #include static u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len) { if (len == 1) *ptr = bytes; else if (len == 2) *(u16 *)ptr = bytes; else { *(u32 *)ptr = bytes; barrier(); } return ptr + len; } #define EMIT(bytes, len) \ do { prog = emit_code(prog, bytes, len); cnt += len; } while (0) #define EMIT1(b1) EMIT(b1, 1) #define EMIT2(b1, b2) EMIT((b1) + ((b2) << 8), 2) #define EMIT3(b1, b2, b3) EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3) #define EMIT4(b1, b2, b3, b4) EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4) #define EMIT1_off32(b1, off) \ do { EMIT1(b1); EMIT(off, 4); } while (0) #define EMIT2_off32(b1, b2, off) \ do { EMIT2(b1, b2); EMIT(off, 4); } while (0) #define EMIT3_off32(b1, b2, b3, off) \ do { EMIT3(b1, b2, b3); EMIT(off, 4); } while (0) #define EMIT4_off32(b1, b2, b3, b4, off) \ do { EMIT4(b1, b2, b3, b4); EMIT(off, 4); } while (0) static bool is_imm8(int value) { return value <= 127 && value >= -128; } static bool is_simm32(s64 value) { return value == (s64)(s32)value; } static bool is_uimm32(u64 value) { return value == (u64)(u32)value; } /* mov dst, src */ #define EMIT_mov(DST, SRC) \ do { \ if (DST != SRC) \ EMIT3(add_2mod(0x48, DST, SRC), 0x89, add_2reg(0xC0, DST, SRC)); \ } while (0) static int bpf_size_to_x86_bytes(int bpf_size) { if (bpf_size == BPF_W) return 4; else if (bpf_size == BPF_H) return 2; else if (bpf_size == BPF_B) return 1; else if (bpf_size == BPF_DW) return 4; /* imm32 */ else return 0; } /* * List of x86 cond jumps opcodes (. + s8) * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32) */ #define X86_JB 0x72 #define X86_JAE 0x73 #define X86_JE 0x74 #define X86_JNE 0x75 #define X86_JBE 0x76 #define X86_JA 0x77 #define X86_JL 0x7C #define X86_JGE 0x7D #define X86_JLE 0x7E #define X86_JG 0x7F /* Pick a register outside of BPF range for JIT internal work */ #define AUX_REG (MAX_BPF_JIT_REG + 1) #define X86_REG_R9 (MAX_BPF_JIT_REG + 2) /* * The following table maps BPF registers to x86-64 registers. * * x86-64 register R12 is unused, since if used as base address * register in load/store instructions, it always needs an * extra byte of encoding and is callee saved. * * x86-64 register R9 is not used by BPF programs, but can be used by BPF * trampoline. x86-64 register R10 is used for blinding (if enabled). */ static const int reg2hex[] = { [BPF_REG_0] = 0, /* RAX */ [BPF_REG_1] = 7, /* RDI */ [BPF_REG_2] = 6, /* RSI */ [BPF_REG_3] = 2, /* RDX */ [BPF_REG_4] = 1, /* RCX */ [BPF_REG_5] = 0, /* R8 */ [BPF_REG_6] = 3, /* RBX callee saved */ [BPF_REG_7] = 5, /* R13 callee saved */ [BPF_REG_8] = 6, /* R14 callee saved */ [BPF_REG_9] = 7, /* R15 callee saved */ [BPF_REG_FP] = 5, /* RBP readonly */ [BPF_REG_AX] = 2, /* R10 temp register */ [AUX_REG] = 3, /* R11 temp register */ [X86_REG_R9] = 1, /* R9 register, 6th function argument */ }; static const int reg2pt_regs[] = { [BPF_REG_0] = offsetof(struct pt_regs, ax), [BPF_REG_1] = offsetof(struct pt_regs, di), [BPF_REG_2] = offsetof(struct pt_regs, si), [BPF_REG_3] = offsetof(struct pt_regs, dx), [BPF_REG_4] = offsetof(struct pt_regs, cx), [BPF_REG_5] = offsetof(struct pt_regs, r8), [BPF_REG_6] = offsetof(struct pt_regs, bx), [BPF_REG_7] = offsetof(struct pt_regs, r13), [BPF_REG_8] = offsetof(struct pt_regs, r14), [BPF_REG_9] = offsetof(struct pt_regs, r15), }; /* * is_ereg() == true if BPF register 'reg' maps to x86-64 r8..r15 * which need extra byte of encoding. * rax,rcx,...,rbp have simpler encoding */ static bool is_ereg(u32 reg) { return (1 << reg) & (BIT(BPF_REG_5) | BIT(AUX_REG) | BIT(BPF_REG_7) | BIT(BPF_REG_8) | BIT(BPF_REG_9) | BIT(X86_REG_R9) | BIT(BPF_REG_AX)); } static bool is_axreg(u32 reg) { return reg == BPF_REG_0; } /* Add modifiers if 'reg' maps to x86-64 registers R8..R15 */ static u8 add_1mod(u8 byte, u32 reg) { if (is_ereg(reg)) byte |= 1; return byte; } static u8 add_2mod(u8 byte, u32 r1, u32 r2) { if (is_ereg(r1)) byte |= 1; if (is_ereg(r2)) byte |= 4; return byte; } /* Encode 'dst_reg' register into x86-64 opcode 'byte' */ static u8 add_1reg(u8 byte, u32 dst_reg) { return byte + reg2hex[dst_reg]; } /* Encode 'dst_reg' and 'src_reg' registers into x86-64 opcode 'byte' */ static u8 add_2reg(u8 byte, u32 dst_reg, u32 src_reg) { return byte + reg2hex[dst_reg] + (reg2hex[src_reg] << 3); } static void jit_fill_hole(void *area, unsigned int size) { /* Fill whole space with INT3 instructions */ memset(area, 0xcc, size); } struct jit_context { int cleanup_addr; /* Epilogue code offset */ }; /* Maximum number of bytes emitted while JITing one eBPF insn */ #define BPF_MAX_INSN_SIZE 128 #define BPF_INSN_SAFETY 64 /* Number of bytes emit_patch() needs to generate instructions */ #define X86_PATCH_SIZE 5 #define PROLOGUE_SIZE 25 /* * Emit x86-64 prologue code for BPF program and check its size. * bpf_tail_call helper will skip it while jumping into another program */ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf) { u8 *prog = *pprog; int cnt = X86_PATCH_SIZE; /* BPF trampoline can be made to work without these nops, * but let's waste 5 bytes for now and optimize later */ memcpy(prog, ideal_nops[NOP_ATOMIC5], cnt); prog += cnt; EMIT1(0x55); /* push rbp */ EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */ /* sub rsp, rounded_stack_depth */ EMIT3_off32(0x48, 0x81, 0xEC, round_up(stack_depth, 8)); EMIT1(0x53); /* push rbx */ EMIT2(0x41, 0x55); /* push r13 */ EMIT2(0x41, 0x56); /* push r14 */ EMIT2(0x41, 0x57); /* push r15 */ if (!ebpf_from_cbpf) { /* zero init tail_call_cnt */ EMIT2(0x6a, 0x00); BUILD_BUG_ON(cnt != PROLOGUE_SIZE); } *pprog = prog; } static int emit_patch(u8 **pprog, void *func, void *ip, u8 opcode) { u8 *prog = *pprog; int cnt = 0; s64 offset; offset = func - (ip + X86_PATCH_SIZE); if (!is_simm32(offset)) { pr_err("Target call %p is out of range\n", func); return -ERANGE; } EMIT1_off32(opcode, offset); *pprog = prog; return 0; } static int emit_call(u8 **pprog, void *func, void *ip) { return emit_patch(pprog, func, ip, 0xE8); } static int emit_jump(u8 **pprog, void *func, void *ip) { return emit_patch(pprog, func, ip, 0xE9); } static int __bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, void *old_addr, void *new_addr, const bool text_live) { const u8 *nop_insn = ideal_nops[NOP_ATOMIC5]; u8 old_insn[X86_PATCH_SIZE]; u8 new_insn[X86_PATCH_SIZE]; u8 *prog; int ret; memcpy(old_insn, nop_insn, X86_PATCH_SIZE); if (old_addr) { prog = old_insn; ret = t == BPF_MOD_CALL ? emit_call(&prog, old_addr, ip) : emit_jump(&prog, old_addr, ip); if (ret) return ret; } memcpy(new_insn, nop_insn, X86_PATCH_SIZE); if (new_addr) { prog = new_insn; ret = t == BPF_MOD_CALL ? emit_call(&prog, new_addr, ip) : emit_jump(&prog, new_addr, ip); if (ret) return ret; } ret = -EBUSY; mutex_lock(&text_mutex); if (memcmp(ip, old_insn, X86_PATCH_SIZE)) goto out; if (memcmp(ip, new_insn, X86_PATCH_SIZE)) { if (text_live) text_poke_bp(ip, new_insn, X86_PATCH_SIZE, NULL); else memcpy(ip, new_insn, X86_PATCH_SIZE); } ret = 0; out: mutex_unlock(&text_mutex); return ret; } int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, void *old_addr, void *new_addr) { if (!is_kernel_text((long)ip) && !is_bpf_text_address((long)ip)) /* BPF poking in modules is not supported */ return -EINVAL; return __bpf_arch_text_poke(ip, t, old_addr, new_addr, true); } /* * Generate the following code: * * ... bpf_tail_call(void *ctx, struct bpf_array *array, u64 index) ... * if (index >= array->map.max_entries) * goto out; * if (++tail_call_cnt > MAX_TAIL_CALL_CNT) * goto out; * prog = array->ptrs[index]; * if (prog == NULL) * goto out; * goto *(prog->bpf_func + prologue_size); * out: */ static void emit_bpf_tail_call_indirect(u8 **pprog) { u8 *prog = *pprog; int label1, label2, label3; int cnt = 0; /* * rdi - pointer to ctx * rsi - pointer to bpf_array * rdx - index in bpf_array */ /* * if (index >= array->map.max_entries) * goto out; */ EMIT2(0x89, 0xD2); /* mov edx, edx */ EMIT3(0x39, 0x56, /* cmp dword ptr [rsi + 16], edx */ offsetof(struct bpf_array, map.max_entries)); #define OFFSET1 (41 + RETPOLINE_RAX_BPF_JIT_SIZE) /* Number of bytes to jump */ EMIT2(X86_JBE, OFFSET1); /* jbe out */ label1 = cnt; /* * if (tail_call_cnt > MAX_TAIL_CALL_CNT) * goto out; */ EMIT2_off32(0x8B, 0x85, -36 - MAX_BPF_STACK); /* mov eax, dword ptr [rbp - 548] */ EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT); /* cmp eax, MAX_TAIL_CALL_CNT */ #define OFFSET2 (30 + RETPOLINE_RAX_BPF_JIT_SIZE) EMIT2(X86_JA, OFFSET2); /* ja out */ label2 = cnt; EMIT3(0x83, 0xC0, 0x01); /* add eax, 1 */ EMIT2_off32(0x89, 0x85, -36 - MAX_BPF_STACK); /* mov dword ptr [rbp -548], eax */ /* prog = array->ptrs[index]; */ EMIT4_off32(0x48, 0x8B, 0x84, 0xD6, /* mov rax, [rsi + rdx * 8 + offsetof(...)] */ offsetof(struct bpf_array, ptrs)); /* * if (prog == NULL) * goto out; */ EMIT3(0x48, 0x85, 0xC0); /* test rax,rax */ #define OFFSET3 (8 + RETPOLINE_RAX_BPF_JIT_SIZE) EMIT2(X86_JE, OFFSET3); /* je out */ label3 = cnt; /* goto *(prog->bpf_func + prologue_size); */ EMIT4(0x48, 0x8B, 0x40, /* mov rax, qword ptr [rax + 32] */ offsetof(struct bpf_prog, bpf_func)); EMIT4(0x48, 0x83, 0xC0, PROLOGUE_SIZE); /* add rax, prologue_size */ /* * Wow we're ready to jump into next BPF program * rdi == ctx (1st arg) * rax == prog->bpf_func + prologue_size */ RETPOLINE_RAX_BPF_JIT(); /* out: */ BUILD_BUG_ON(cnt - label1 != OFFSET1); BUILD_BUG_ON(cnt - label2 != OFFSET2); BUILD_BUG_ON(cnt - label3 != OFFSET3); *pprog = prog; } static void emit_bpf_tail_call_direct(struct bpf_jit_poke_descriptor *poke, u8 **pprog, int addr, u8 *image) { u8 *prog = *pprog; int cnt = 0; /* * if (tail_call_cnt > MAX_TAIL_CALL_CNT) * goto out; */ EMIT2_off32(0x8B, 0x85, -36 - MAX_BPF_STACK); /* mov eax, dword ptr [rbp - 548] */ EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT); /* cmp eax, MAX_TAIL_CALL_CNT */ EMIT2(X86_JA, 14); /* ja out */ EMIT3(0x83, 0xC0, 0x01); /* add eax, 1 */ EMIT2_off32(0x89, 0x85, -36 - MAX_BPF_STACK); /* mov dword ptr [rbp -548], eax */ poke->ip = image + (addr - X86_PATCH_SIZE); poke->adj_off = PROLOGUE_SIZE; memcpy(prog, ideal_nops[NOP_ATOMIC5], X86_PATCH_SIZE); prog += X86_PATCH_SIZE; /* out: */ *pprog = prog; } static void bpf_tail_call_direct_fixup(struct bpf_prog *prog) { struct bpf_jit_poke_descriptor *poke; struct bpf_array *array; struct bpf_prog *target; int i, ret; for (i = 0; i < prog->aux->size_poke_tab; i++) { poke = &prog->aux->poke_tab[i]; WARN_ON_ONCE(READ_ONCE(poke->ip_stable)); if (poke->reason != BPF_POKE_REASON_TAIL_CALL) continue; array = container_of(poke->tail_call.map, struct bpf_array, map); mutex_lock(&array->aux->poke_mutex); target = array->ptrs[poke->tail_call.key]; if (target) { /* Plain memcpy is used when image is not live yet * and still not locked as read-only. Once poke * location is active (poke->ip_stable), any parallel * bpf_arch_text_poke() might occur still on the * read-write image until we finally locked it as * read-only. Both modifications on the given image * are under text_mutex to avoid interference. */ ret = __bpf_arch_text_poke(poke->ip, BPF_MOD_JUMP, NULL, (u8 *)target->bpf_func + poke->adj_off, false); BUG_ON(ret < 0); } WRITE_ONCE(poke->ip_stable, true); mutex_unlock(&array->aux->poke_mutex); } } static void emit_mov_imm32(u8 **pprog, bool sign_propagate, u32 dst_reg, const u32 imm32) { u8 *prog = *pprog; u8 b1, b2, b3; int cnt = 0; /* * Optimization: if imm32 is positive, use 'mov %eax, imm32' * (which zero-extends imm32) to save 2 bytes. */ if (sign_propagate && (s32)imm32 < 0) { /* 'mov %rax, imm32' sign extends imm32 */ b1 = add_1mod(0x48, dst_reg); b2 = 0xC7; b3 = 0xC0; EMIT3_off32(b1, b2, add_1reg(b3, dst_reg), imm32); goto done; } /* * Optimization: if imm32 is zero, use 'xor %eax, %eax' * to save 3 bytes. */ if (imm32 == 0) { if (is_ereg(dst_reg)) EMIT1(add_2mod(0x40, dst_reg, dst_reg)); b2 = 0x31; /* xor */ b3 = 0xC0; EMIT2(b2, add_2reg(b3, dst_reg, dst_reg)); goto done; } /* mov %eax, imm32 */ if (is_ereg(dst_reg)) EMIT1(add_1mod(0x40, dst_reg)); EMIT1_off32(add_1reg(0xB8, dst_reg), imm32); done: *pprog = prog; } static void emit_mov_imm64(u8 **pprog, u32 dst_reg, const u32 imm32_hi, const u32 imm32_lo) { u8 *prog = *pprog; int cnt = 0; if (is_uimm32(((u64)imm32_hi << 32) | (u32)imm32_lo)) { /* * For emitting plain u32, where sign bit must not be * propagated LLVM tends to load imm64 over mov32 * directly, so save couple of bytes by just doing * 'mov %eax, imm32' instead. */ emit_mov_imm32(&prog, false, dst_reg, imm32_lo); } else { /* movabsq %rax, imm64 */ EMIT2(add_1mod(0x48, dst_reg), add_1reg(0xB8, dst_reg)); EMIT(imm32_lo, 4); EMIT(imm32_hi, 4); } *pprog = prog; } static void emit_mov_reg(u8 **pprog, bool is64, u32 dst_reg, u32 src_reg) { u8 *prog = *pprog; int cnt = 0; if (is64) { /* mov dst, src */ EMIT_mov(dst_reg, src_reg); } else { /* mov32 dst, src */ if (is_ereg(dst_reg) || is_ereg(src_reg)) EMIT1(add_2mod(0x40, dst_reg, src_reg)); EMIT2(0x89, add_2reg(0xC0, dst_reg, src_reg)); } *pprog = prog; } /* LDX: dst_reg = *(u8*)(src_reg + off) */ static void emit_ldx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off) { u8 *prog = *pprog; int cnt = 0; switch (size) { case BPF_B: /* Emit 'movzx rax, byte ptr [rax + off]' */ EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x0F, 0xB6); break; case BPF_H: /* Emit 'movzx rax, word ptr [rax + off]' */ EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x0F, 0xB7); break; case BPF_W: /* Emit 'mov eax, dword ptr [rax+0x14]' */ if (is_ereg(dst_reg) || is_ereg(src_reg)) EMIT2(add_2mod(0x40, src_reg, dst_reg), 0x8B); else EMIT1(0x8B); break; case BPF_DW: /* Emit 'mov rax, qword ptr [rax+0x14]' */ EMIT2(add_2mod(0x48, src_reg, dst_reg), 0x8B); break; } /* * If insn->off == 0 we can save one extra byte, but * special case of x86 R13 which always needs an offset * is not worth the hassle */ if (is_imm8(off)) EMIT2(add_2reg(0x40, src_reg, dst_reg), off); else EMIT1_off32(add_2reg(0x80, src_reg, dst_reg), off); *pprog = prog; } /* STX: *(u8*)(dst_reg + off) = src_reg */ static void emit_stx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off) { u8 *prog = *pprog; int cnt = 0; switch (size) { case BPF_B: /* Emit 'mov byte ptr [rax + off], al' */ if (is_ereg(dst_reg) || is_ereg(src_reg) || /* We have to add extra byte for x86 SIL, DIL regs */ src_reg == BPF_REG_1 || src_reg == BPF_REG_2) EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x88); else EMIT1(0x88); break; case BPF_H: if (is_ereg(dst_reg) || is_ereg(src_reg)) EMIT3(0x66, add_2mod(0x40, dst_reg, src_reg), 0x89); else EMIT2(0x66, 0x89); break; case BPF_W: if (is_ereg(dst_reg) || is_ereg(src_reg)) EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x89); else EMIT1(0x89); break; case BPF_DW: EMIT2(add_2mod(0x48, dst_reg, src_reg), 0x89); break; } if (is_imm8(off)) EMIT2(add_2reg(0x40, dst_reg, src_reg), off); else EMIT1_off32(add_2reg(0x80, dst_reg, src_reg), off); *pprog = prog; } static bool ex_handler_bpf(const struct exception_table_entry *x, struct pt_regs *regs, int trapnr, unsigned long error_code, unsigned long fault_addr) { u32 reg = x->fixup >> 8; /* jump over faulting load and clear dest register */ *(unsigned long *)((void *)regs + reg) = 0; regs->ip += x->fixup & 0xff; return true; } static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, int oldproglen, struct jit_context *ctx) { struct bpf_insn *insn = bpf_prog->insnsi; int insn_cnt = bpf_prog->len; bool seen_exit = false; u8 temp[BPF_MAX_INSN_SIZE + BPF_INSN_SAFETY]; int i, cnt = 0, excnt = 0; int proglen = 0; u8 *prog = temp; emit_prologue(&prog, bpf_prog->aux->stack_depth, bpf_prog_was_classic(bpf_prog)); addrs[0] = prog - temp; for (i = 1; i <= insn_cnt; i++, insn++) { const s32 imm32 = insn->imm; u32 dst_reg = insn->dst_reg; u32 src_reg = insn->src_reg; u8 b2 = 0, b3 = 0; s64 jmp_offset; u8 jmp_cond; int ilen; u8 *func; switch (insn->code) { /* ALU */ case BPF_ALU | BPF_ADD | BPF_X: case BPF_ALU | BPF_SUB | BPF_X: case BPF_ALU | BPF_AND | BPF_X: case BPF_ALU | BPF_OR | BPF_X: case BPF_ALU | BPF_XOR | BPF_X: case BPF_ALU64 | BPF_ADD | BPF_X: case BPF_ALU64 | BPF_SUB | BPF_X: case BPF_ALU64 | BPF_AND | BPF_X: case BPF_ALU64 | BPF_OR | BPF_X: case BPF_ALU64 | BPF_XOR | BPF_X: switch (BPF_OP(insn->code)) { case BPF_ADD: b2 = 0x01; break; case BPF_SUB: b2 = 0x29; break; case BPF_AND: b2 = 0x21; break; case BPF_OR: b2 = 0x09; break; case BPF_XOR: b2 = 0x31; break; } if (BPF_CLASS(insn->code) == BPF_ALU64) EMIT1(add_2mod(0x48, dst_reg, src_reg)); else if (is_ereg(dst_reg) || is_ereg(src_reg)) EMIT1(add_2mod(0x40, dst_reg, src_reg)); EMIT2(b2, add_2reg(0xC0, dst_reg, src_reg)); break; case BPF_ALU64 | BPF_MOV | BPF_X: case BPF_ALU | BPF_MOV | BPF_X: emit_mov_reg(&prog, BPF_CLASS(insn->code) == BPF_ALU64, dst_reg, src_reg); break; /* neg dst */ case BPF_ALU | BPF_NEG: case BPF_ALU64 | BPF_NEG: if (BPF_CLASS(insn->code) == BPF_ALU64) EMIT1(add_1mod(0x48, dst_reg)); else if (is_ereg(dst_reg)) EMIT1(add_1mod(0x40, dst_reg)); EMIT2(0xF7, add_1reg(0xD8, dst_reg)); break; case BPF_ALU | BPF_ADD | BPF_K: case BPF_ALU | BPF_SUB | BPF_K: case BPF_ALU | BPF_AND | BPF_K: case BPF_ALU | BPF_OR | BPF_K: case BPF_ALU | BPF_XOR | BPF_K: case BPF_ALU64 | BPF_ADD | BPF_K: case BPF_ALU64 | BPF_SUB | BPF_K: case BPF_ALU64 | BPF_AND | BPF_K: case BPF_ALU64 | BPF_OR | BPF_K: case BPF_ALU64 | BPF_XOR | BPF_K: if (BPF_CLASS(insn->code) == BPF_ALU64) EMIT1(add_1mod(0x48, dst_reg)); else if (is_ereg(dst_reg)) EMIT1(add_1mod(0x40, dst_reg)); /* * b3 holds 'normal' opcode, b2 short form only valid * in case dst is eax/rax. */ switch (BPF_OP(insn->code)) { case BPF_ADD: b3 = 0xC0; b2 = 0x05; break; case BPF_SUB: b3 = 0xE8; b2 = 0x2D; break; case BPF_AND: b3 = 0xE0; b2 = 0x25; break; case BPF_OR: b3 = 0xC8; b2 = 0x0D; break; case BPF_XOR: b3 = 0xF0; b2 = 0x35; break; } if (is_imm8(imm32)) EMIT3(0x83, add_1reg(b3, dst_reg), imm32); else if (is_axreg(dst_reg)) EMIT1_off32(b2, imm32); else EMIT2_off32(0x81, add_1reg(b3, dst_reg), imm32); break; case BPF_ALU64 | BPF_MOV | BPF_K: case BPF_ALU | BPF_MOV | BPF_K: emit_mov_imm32(&prog, BPF_CLASS(insn->code) == BPF_ALU64, dst_reg, imm32); break; case BPF_LD | BPF_IMM | BPF_DW: emit_mov_imm64(&prog, dst_reg, insn[1].imm, insn[0].imm); insn++; i++; break; /* dst %= src, dst /= src, dst %= imm32, dst /= imm32 */ case BPF_ALU | BPF_MOD | BPF_X: case BPF_ALU | BPF_DIV | BPF_X: case BPF_ALU | BPF_MOD | BPF_K: case BPF_ALU | BPF_DIV | BPF_K: case BPF_ALU64 | BPF_MOD | BPF_X: case BPF_ALU64 | BPF_DIV | BPF_X: case BPF_ALU64 | BPF_MOD | BPF_K: case BPF_ALU64 | BPF_DIV | BPF_K: EMIT1(0x50); /* push rax */ EMIT1(0x52); /* push rdx */ if (BPF_SRC(insn->code) == BPF_X) /* mov r11, src_reg */ EMIT_mov(AUX_REG, src_reg); else /* mov r11, imm32 */ EMIT3_off32(0x49, 0xC7, 0xC3, imm32); /* mov rax, dst_reg */ EMIT_mov(BPF_REG_0, dst_reg); /* * xor edx, edx * equivalent to 'xor rdx, rdx', but one byte less */ EMIT2(0x31, 0xd2); if (BPF_CLASS(insn->code) == BPF_ALU64) /* div r11 */ EMIT3(0x49, 0xF7, 0xF3); else /* div r11d */ EMIT3(0x41, 0xF7, 0xF3); if (BPF_OP(insn->code) == BPF_MOD) /* mov r11, rdx */ EMIT3(0x49, 0x89, 0xD3); else /* mov r11, rax */ EMIT3(0x49, 0x89, 0xC3); EMIT1(0x5A); /* pop rdx */ EMIT1(0x58); /* pop rax */ /* mov dst_reg, r11 */ EMIT_mov(dst_reg, AUX_REG); break; case BPF_ALU | BPF_MUL | BPF_K: case BPF_ALU | BPF_MUL | BPF_X: case BPF_ALU64 | BPF_MUL | BPF_K: case BPF_ALU64 | BPF_MUL | BPF_X: { bool is64 = BPF_CLASS(insn->code) == BPF_ALU64; if (dst_reg != BPF_REG_0) EMIT1(0x50); /* push rax */ if (dst_reg != BPF_REG_3) EMIT1(0x52); /* push rdx */ /* mov r11, dst_reg */ EMIT_mov(AUX_REG, dst_reg); if (BPF_SRC(insn->code) == BPF_X) emit_mov_reg(&prog, is64, BPF_REG_0, src_reg); else emit_mov_imm32(&prog, is64, BPF_REG_0, imm32); if (is64) EMIT1(add_1mod(0x48, AUX_REG)); else if (is_ereg(AUX_REG)) EMIT1(add_1mod(0x40, AUX_REG)); /* mul(q) r11 */ EMIT2(0xF7, add_1reg(0xE0, AUX_REG)); if (dst_reg != BPF_REG_3) EMIT1(0x5A); /* pop rdx */ if (dst_reg != BPF_REG_0) { /* mov dst_reg, rax */ EMIT_mov(dst_reg, BPF_REG_0); EMIT1(0x58); /* pop rax */ } break; } /* Shifts */ case BPF_ALU | BPF_LSH | BPF_K: case BPF_ALU | BPF_RSH | BPF_K: case BPF_ALU | BPF_ARSH | BPF_K: case BPF_ALU64 | BPF_LSH | BPF_K: case BPF_ALU64 | BPF_RSH | BPF_K: case BPF_ALU64 | BPF_ARSH | BPF_K: if (BPF_CLASS(insn->code) == BPF_ALU64) EMIT1(add_1mod(0x48, dst_reg)); else if (is_ereg(dst_reg)) EMIT1(add_1mod(0x40, dst_reg)); switch (BPF_OP(insn->code)) { case BPF_LSH: b3 = 0xE0; break; case BPF_RSH: b3 = 0xE8; break; case BPF_ARSH: b3 = 0xF8; break; } if (imm32 == 1) EMIT2(0xD1, add_1reg(b3, dst_reg)); else EMIT3(0xC1, add_1reg(b3, dst_reg), imm32); break; case BPF_ALU | BPF_LSH | BPF_X: case BPF_ALU | BPF_RSH | BPF_X: case BPF_ALU | BPF_ARSH | BPF_X: case BPF_ALU64 | BPF_LSH | BPF_X: case BPF_ALU64 | BPF_RSH | BPF_X: case BPF_ALU64 | BPF_ARSH | BPF_X: /* Check for bad case when dst_reg == rcx */ if (dst_reg == BPF_REG_4) { /* mov r11, dst_reg */ EMIT_mov(AUX_REG, dst_reg); dst_reg = AUX_REG; } if (src_reg != BPF_REG_4) { /* common case */ EMIT1(0x51); /* push rcx */ /* mov rcx, src_reg */ EMIT_mov(BPF_REG_4, src_reg); } /* shl %rax, %cl | shr %rax, %cl | sar %rax, %cl */ if (BPF_CLASS(insn->code) == BPF_ALU64) EMIT1(add_1mod(0x48, dst_reg)); else if (is_ereg(dst_reg)) EMIT1(add_1mod(0x40, dst_reg)); switch (BPF_OP(insn->code)) { case BPF_LSH: b3 = 0xE0; break; case BPF_RSH: b3 = 0xE8; break; case BPF_ARSH: b3 = 0xF8; break; } EMIT2(0xD3, add_1reg(b3, dst_reg)); if (src_reg != BPF_REG_4) EMIT1(0x59); /* pop rcx */ if (insn->dst_reg == BPF_REG_4) /* mov dst_reg, r11 */ EMIT_mov(insn->dst_reg, AUX_REG); break; case BPF_ALU | BPF_END | BPF_FROM_BE: switch (imm32) { case 16: /* Emit 'ror %ax, 8' to swap lower 2 bytes */ EMIT1(0x66); if (is_ereg(dst_reg)) EMIT1(0x41); EMIT3(0xC1, add_1reg(0xC8, dst_reg), 8); /* Emit 'movzwl eax, ax' */ if (is_ereg(dst_reg)) EMIT3(0x45, 0x0F, 0xB7); else EMIT2(0x0F, 0xB7); EMIT1(add_2reg(0xC0, dst_reg, dst_reg)); break; case 32: /* Emit 'bswap eax' to swap lower 4 bytes */ if (is_ereg(dst_reg)) EMIT2(0x41, 0x0F); else EMIT1(0x0F); EMIT1(add_1reg(0xC8, dst_reg)); break; case 64: /* Emit 'bswap rax' to swap 8 bytes */ EMIT3(add_1mod(0x48, dst_reg), 0x0F, add_1reg(0xC8, dst_reg)); break; } break; case BPF_ALU | BPF_END | BPF_FROM_LE: switch (imm32) { case 16: /* * Emit 'movzwl eax, ax' to zero extend 16-bit * into 64 bit */ if (is_ereg(dst_reg)) EMIT3(0x45, 0x0F, 0xB7); else EMIT2(0x0F, 0xB7); EMIT1(add_2reg(0xC0, dst_reg, dst_reg)); break; case 32: /* Emit 'mov eax, eax' to clear upper 32-bits */ if (is_ereg(dst_reg)) EMIT1(0x45); EMIT2(0x89, add_2reg(0xC0, dst_reg, dst_reg)); break; case 64: /* nop */ break; } break; /* ST: *(u8*)(dst_reg + off) = imm */ case BPF_ST | BPF_MEM | BPF_B: if (is_ereg(dst_reg)) EMIT2(0x41, 0xC6); else EMIT1(0xC6); goto st; case BPF_ST | BPF_MEM | BPF_H: if (is_ereg(dst_reg)) EMIT3(0x66, 0x41, 0xC7); else EMIT2(0x66, 0xC7); goto st; case BPF_ST | BPF_MEM | BPF_W: if (is_ereg(dst_reg)) EMIT2(0x41, 0xC7); else EMIT1(0xC7); goto st; case BPF_ST | BPF_MEM | BPF_DW: EMIT2(add_1mod(0x48, dst_reg), 0xC7); st: if (is_imm8(insn->off)) EMIT2(add_1reg(0x40, dst_reg), insn->off); else EMIT1_off32(add_1reg(0x80, dst_reg), insn->off); EMIT(imm32, bpf_size_to_x86_bytes(BPF_SIZE(insn->code))); break; /* STX: *(u8*)(dst_reg + off) = src_reg */ case BPF_STX | BPF_MEM | BPF_B: case BPF_STX | BPF_MEM | BPF_H: case BPF_STX | BPF_MEM | BPF_W: case BPF_STX | BPF_MEM | BPF_DW: emit_stx(&prog, BPF_SIZE(insn->code), dst_reg, src_reg, insn->off); break; /* LDX: dst_reg = *(u8*)(src_reg + off) */ case BPF_LDX | BPF_MEM | BPF_B: case BPF_LDX | BPF_PROBE_MEM | BPF_B: case BPF_LDX | BPF_MEM | BPF_H: case BPF_LDX | BPF_PROBE_MEM | BPF_H: case BPF_LDX | BPF_MEM | BPF_W: case BPF_LDX | BPF_PROBE_MEM | BPF_W: case BPF_LDX | BPF_MEM | BPF_DW: case BPF_LDX | BPF_PROBE_MEM | BPF_DW: emit_ldx(&prog, BPF_SIZE(insn->code), dst_reg, src_reg, insn->off); if (BPF_MODE(insn->code) == BPF_PROBE_MEM) { struct exception_table_entry *ex; u8 *_insn = image + proglen; s64 delta; if (!bpf_prog->aux->extable) break; if (excnt >= bpf_prog->aux->num_exentries) { pr_err("ex gen bug\n"); return -EFAULT; } ex = &bpf_prog->aux->extable[excnt++]; delta = _insn - (u8 *)&ex->insn; if (!is_simm32(delta)) { pr_err("extable->insn doesn't fit into 32-bit\n"); return -EFAULT; } ex->insn = delta; delta = (u8 *)ex_handler_bpf - (u8 *)&ex->handler; if (!is_simm32(delta)) { pr_err("extable->handler doesn't fit into 32-bit\n"); return -EFAULT; } ex->handler = delta; if (dst_reg > BPF_REG_9) { pr_err("verifier error\n"); return -EFAULT; } /* * Compute size of x86 insn and its target dest x86 register. * ex_handler_bpf() will use lower 8 bits to adjust * pt_regs->ip to jump over this x86 instruction * and upper bits to figure out which pt_regs to zero out. * End result: x86 insn "mov rbx, qword ptr [rax+0x14]" * of 4 bytes will be ignored and rbx will be zero inited. */ ex->fixup = (prog - temp) | (reg2pt_regs[dst_reg] << 8); } break; /* STX XADD: lock *(u32*)(dst_reg + off) += src_reg */ case BPF_STX | BPF_XADD | BPF_W: /* Emit 'lock add dword ptr [rax + off], eax' */ if (is_ereg(dst_reg) || is_ereg(src_reg)) EMIT3(0xF0, add_2mod(0x40, dst_reg, src_reg), 0x01); else EMIT2(0xF0, 0x01); goto xadd; case BPF_STX | BPF_XADD | BPF_DW: EMIT3(0xF0, add_2mod(0x48, dst_reg, src_reg), 0x01); xadd: if (is_imm8(insn->off)) EMIT2(add_2reg(0x40, dst_reg, src_reg), insn->off); else EMIT1_off32(add_2reg(0x80, dst_reg, src_reg), insn->off); break; /* call */ case BPF_JMP | BPF_CALL: func = (u8 *) __bpf_call_base + imm32; if (!imm32 || emit_call(&prog, func, image + addrs[i - 1])) return -EINVAL; break; case BPF_JMP | BPF_TAIL_CALL: if (imm32) emit_bpf_tail_call_direct(&bpf_prog->aux->poke_tab[imm32 - 1], &prog, addrs[i], image); else emit_bpf_tail_call_indirect(&prog); break; /* cond jump */ case BPF_JMP | BPF_JEQ | BPF_X: case BPF_JMP | BPF_JNE | BPF_X: case BPF_JMP | BPF_JGT | BPF_X: case BPF_JMP | BPF_JLT | BPF_X: case BPF_JMP | BPF_JGE | BPF_X: case BPF_JMP | BPF_JLE | BPF_X: case BPF_JMP | BPF_JSGT | BPF_X: case BPF_JMP | BPF_JSLT | BPF_X: case BPF_JMP | BPF_JSGE | BPF_X: case BPF_JMP | BPF_JSLE | BPF_X: case BPF_JMP32 | BPF_JEQ | BPF_X: case BPF_JMP32 | BPF_JNE | BPF_X: case BPF_JMP32 | BPF_JGT | BPF_X: case BPF_JMP32 | BPF_JLT | BPF_X: case BPF_JMP32 | BPF_JGE | BPF_X: case BPF_JMP32 | BPF_JLE | BPF_X: case BPF_JMP32 | BPF_JSGT | BPF_X: case BPF_JMP32 | BPF_JSLT | BPF_X: case BPF_JMP32 | BPF_JSGE | BPF_X: case BPF_JMP32 | BPF_JSLE | BPF_X: /* cmp dst_reg, src_reg */ if (BPF_CLASS(insn->code) == BPF_JMP) EMIT1(add_2mod(0x48, dst_reg, src_reg)); else if (is_ereg(dst_reg) || is_ereg(src_reg)) EMIT1(add_2mod(0x40, dst_reg, src_reg)); EMIT2(0x39, add_2reg(0xC0, dst_reg, src_reg)); goto emit_cond_jmp; case BPF_JMP | BPF_JSET | BPF_X: case BPF_JMP32 | BPF_JSET | BPF_X: /* test dst_reg, src_reg */ if (BPF_CLASS(insn->code) == BPF_JMP) EMIT1(add_2mod(0x48, dst_reg, src_reg)); else if (is_ereg(dst_reg) || is_ereg(src_reg)) EMIT1(add_2mod(0x40, dst_reg, src_reg)); EMIT2(0x85, add_2reg(0xC0, dst_reg, src_reg)); goto emit_cond_jmp; case BPF_JMP | BPF_JSET | BPF_K: case BPF_JMP32 | BPF_JSET | BPF_K: /* test dst_reg, imm32 */ if (BPF_CLASS(insn->code) == BPF_JMP) EMIT1(add_1mod(0x48, dst_reg)); else if (is_ereg(dst_reg)) EMIT1(add_1mod(0x40, dst_reg)); EMIT2_off32(0xF7, add_1reg(0xC0, dst_reg), imm32); goto emit_cond_jmp; case BPF_JMP | BPF_JEQ | BPF_K: case BPF_JMP | BPF_JNE | BPF_K: case BPF_JMP | BPF_JGT | BPF_K: case BPF_JMP | BPF_JLT | BPF_K: case BPF_JMP | BPF_JGE | BPF_K: case BPF_JMP | BPF_JLE | BPF_K: case BPF_JMP | BPF_JSGT | BPF_K: case BPF_JMP | BPF_JSLT | BPF_K: case BPF_JMP | BPF_JSGE | BPF_K: case BPF_JMP | BPF_JSLE | BPF_K: case BPF_JMP32 | BPF_JEQ | BPF_K: case BPF_JMP32 | BPF_JNE | BPF_K: case BPF_JMP32 | BPF_JGT | BPF_K: case BPF_JMP32 | BPF_JLT | BPF_K: case BPF_JMP32 | BPF_JGE | BPF_K: case BPF_JMP32 | BPF_JLE | BPF_K: case BPF_JMP32 | BPF_JSGT | BPF_K: case BPF_JMP32 | BPF_JSLT | BPF_K: case BPF_JMP32 | BPF_JSGE | BPF_K: case BPF_JMP32 | BPF_JSLE | BPF_K: /* test dst_reg, dst_reg to save one extra byte */ if (imm32 == 0) { if (BPF_CLASS(insn->code) == BPF_JMP) EMIT1(add_2mod(0x48, dst_reg, dst_reg)); else if (is_ereg(dst_reg)) EMIT1(add_2mod(0x40, dst_reg, dst_reg)); EMIT2(0x85, add_2reg(0xC0, dst_reg, dst_reg)); goto emit_cond_jmp; } /* cmp dst_reg, imm8/32 */ if (BPF_CLASS(insn->code) == BPF_JMP) EMIT1(add_1mod(0x48, dst_reg)); else if (is_ereg(dst_reg)) EMIT1(add_1mod(0x40, dst_reg)); if (is_imm8(imm32)) EMIT3(0x83, add_1reg(0xF8, dst_reg), imm32); else EMIT2_off32(0x81, add_1reg(0xF8, dst_reg), imm32); emit_cond_jmp: /* Convert BPF opcode to x86 */ switch (BPF_OP(insn->code)) { case BPF_JEQ: jmp_cond = X86_JE; break; case BPF_JSET: case BPF_JNE: jmp_cond = X86_JNE; break; case BPF_JGT: /* GT is unsigned '>', JA in x86 */ jmp_cond = X86_JA; break; case BPF_JLT: /* LT is unsigned '<', JB in x86 */ jmp_cond = X86_JB; break; case BPF_JGE: /* GE is unsigned '>=', JAE in x86 */ jmp_cond = X86_JAE; break; case BPF_JLE: /* LE is unsigned '<=', JBE in x86 */ jmp_cond = X86_JBE; break; case BPF_JSGT: /* Signed '>', GT in x86 */ jmp_cond = X86_JG; break; case BPF_JSLT: /* Signed '<', LT in x86 */ jmp_cond = X86_JL; break; case BPF_JSGE: /* Signed '>=', GE in x86 */ jmp_cond = X86_JGE; break; case BPF_JSLE: /* Signed '<=', LE in x86 */ jmp_cond = X86_JLE; break; default: /* to silence GCC warning */ return -EFAULT; } jmp_offset = addrs[i + insn->off] - addrs[i]; if (is_imm8(jmp_offset)) { EMIT2(jmp_cond, jmp_offset); } else if (is_simm32(jmp_offset)) { EMIT2_off32(0x0F, jmp_cond + 0x10, jmp_offset); } else { pr_err("cond_jmp gen bug %llx\n", jmp_offset); return -EFAULT; } break; case BPF_JMP | BPF_JA: if (insn->off == -1) /* -1 jmp instructions will always jump * backwards two bytes. Explicitly handling * this case avoids wasting too many passes * when there are long sequences of replaced * dead code. */ jmp_offset = -2; else jmp_offset = addrs[i + insn->off] - addrs[i]; if (!jmp_offset) /* Optimize out nop jumps */ break; emit_jmp: if (is_imm8(jmp_offset)) { EMIT2(0xEB, jmp_offset); } else if (is_simm32(jmp_offset)) { EMIT1_off32(0xE9, jmp_offset); } else { pr_err("jmp gen bug %llx\n", jmp_offset); return -EFAULT; } break; case BPF_JMP | BPF_EXIT: if (seen_exit) { jmp_offset = ctx->cleanup_addr - addrs[i]; goto emit_jmp; } seen_exit = true; /* Update cleanup_addr */ ctx->cleanup_addr = proglen; if (!bpf_prog_was_classic(bpf_prog)) EMIT1(0x5B); /* get rid of tail_call_cnt */ EMIT2(0x41, 0x5F); /* pop r15 */ EMIT2(0x41, 0x5E); /* pop r14 */ EMIT2(0x41, 0x5D); /* pop r13 */ EMIT1(0x5B); /* pop rbx */ EMIT1(0xC9); /* leave */ EMIT1(0xC3); /* ret */ break; default: /* * By design x86-64 JIT should support all BPF instructions. * This error will be seen if new instruction was added * to the interpreter, but not to the JIT, or if there is * junk in bpf_prog. */ pr_err("bpf_jit: unknown opcode %02x\n", insn->code); return -EINVAL; } ilen = prog - temp; if (ilen > BPF_MAX_INSN_SIZE) { pr_err("bpf_jit: fatal insn size error\n"); return -EFAULT; } if (image) { if (unlikely(proglen + ilen > oldproglen)) { pr_err("bpf_jit: fatal error\n"); return -EFAULT; } memcpy(image + proglen, temp, ilen); } proglen += ilen; addrs[i] = proglen; prog = temp; } if (image && excnt != bpf_prog->aux->num_exentries) { pr_err("extable is not populated\n"); return -EFAULT; } return proglen; } static void save_regs(const struct btf_func_model *m, u8 **prog, int nr_args, int stack_size) { int i; /* Store function arguments to stack. * For a function that accepts two pointers the sequence will be: * mov QWORD PTR [rbp-0x10],rdi * mov QWORD PTR [rbp-0x8],rsi */ for (i = 0; i < min(nr_args, 6); i++) emit_stx(prog, bytes_to_bpf_size(m->arg_size[i]), BPF_REG_FP, i == 5 ? X86_REG_R9 : BPF_REG_1 + i, -(stack_size - i * 8)); } static void restore_regs(const struct btf_func_model *m, u8 **prog, int nr_args, int stack_size) { int i; /* Restore function arguments from stack. * For a function that accepts two pointers the sequence will be: * EMIT4(0x48, 0x8B, 0x7D, 0xF0); mov rdi,QWORD PTR [rbp-0x10] * EMIT4(0x48, 0x8B, 0x75, 0xF8); mov rsi,QWORD PTR [rbp-0x8] */ for (i = 0; i < min(nr_args, 6); i++) emit_ldx(prog, bytes_to_bpf_size(m->arg_size[i]), i == 5 ? X86_REG_R9 : BPF_REG_1 + i, BPF_REG_FP, -(stack_size - i * 8)); } static int invoke_bpf(const struct btf_func_model *m, u8 **pprog, struct bpf_prog **progs, int prog_cnt, int stack_size) { u8 *prog = *pprog; int cnt = 0, i; for (i = 0; i < prog_cnt; i++) { if (emit_call(&prog, __bpf_prog_enter, prog)) return -EINVAL; /* remember prog start time returned by __bpf_prog_enter */ emit_mov_reg(&prog, true, BPF_REG_6, BPF_REG_0); /* arg1: lea rdi, [rbp - stack_size] */ EMIT4(0x48, 0x8D, 0x7D, -stack_size); /* arg2: progs[i]->insnsi for interpreter */ if (!progs[i]->jited) emit_mov_imm64(&prog, BPF_REG_2, (long) progs[i]->insnsi >> 32, (u32) (long) progs[i]->insnsi); /* call JITed bpf program or interpreter */ if (emit_call(&prog, progs[i]->bpf_func, prog)) return -EINVAL; /* arg1: mov rdi, progs[i] */ emit_mov_imm64(&prog, BPF_REG_1, (long) progs[i] >> 32, (u32) (long) progs[i]); /* arg2: mov rsi, rbx <- start time in nsec */ emit_mov_reg(&prog, true, BPF_REG_2, BPF_REG_6); if (emit_call(&prog, __bpf_prog_exit, prog)) return -EINVAL; } *pprog = prog; return 0; } /* Example: * __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev); * its 'struct btf_func_model' will be nr_args=2 * The assembly code when eth_type_trans is executing after trampoline: * * push rbp * mov rbp, rsp * sub rsp, 16 // space for skb and dev * push rbx // temp regs to pass start time * mov qword ptr [rbp - 16], rdi // save skb pointer to stack * mov qword ptr [rbp - 8], rsi // save dev pointer to stack * call __bpf_prog_enter // rcu_read_lock and preempt_disable * mov rbx, rax // remember start time in bpf stats are enabled * lea rdi, [rbp - 16] // R1==ctx of bpf prog * call addr_of_jited_FENTRY_prog * movabsq rdi, 64bit_addr_of_struct_bpf_prog // unused if bpf stats are off * mov rsi, rbx // prog start time * call __bpf_prog_exit // rcu_read_unlock, preempt_enable and stats math * mov rdi, qword ptr [rbp - 16] // restore skb pointer from stack * mov rsi, qword ptr [rbp - 8] // restore dev pointer from stack * pop rbx * leave * ret * * eth_type_trans has 5 byte nop at the beginning. These 5 bytes will be * replaced with 'call generated_bpf_trampoline'. When it returns * eth_type_trans will continue executing with original skb and dev pointers. * * The assembly code when eth_type_trans is called from trampoline: * * push rbp * mov rbp, rsp * sub rsp, 24 // space for skb, dev, return value * push rbx // temp regs to pass start time * mov qword ptr [rbp - 24], rdi // save skb pointer to stack * mov qword ptr [rbp - 16], rsi // save dev pointer to stack * call __bpf_prog_enter // rcu_read_lock and preempt_disable * mov rbx, rax // remember start time if bpf stats are enabled * lea rdi, [rbp - 24] // R1==ctx of bpf prog * call addr_of_jited_FENTRY_prog // bpf prog can access skb and dev * movabsq rdi, 64bit_addr_of_struct_bpf_prog // unused if bpf stats are off * mov rsi, rbx // prog start time * call __bpf_prog_exit // rcu_read_unlock, preempt_enable and stats math * mov rdi, qword ptr [rbp - 24] // restore skb pointer from stack * mov rsi, qword ptr [rbp - 16] // restore dev pointer from stack * call eth_type_trans+5 // execute body of eth_type_trans * mov qword ptr [rbp - 8], rax // save return value * call __bpf_prog_enter // rcu_read_lock and preempt_disable * mov rbx, rax // remember start time in bpf stats are enabled * lea rdi, [rbp - 24] // R1==ctx of bpf prog * call addr_of_jited_FEXIT_prog // bpf prog can access skb, dev, return value * movabsq rdi, 64bit_addr_of_struct_bpf_prog // unused if bpf stats are off * mov rsi, rbx // prog start time * call __bpf_prog_exit // rcu_read_unlock, preempt_enable and stats math * mov rax, qword ptr [rbp - 8] // restore eth_type_trans's return value * pop rbx * leave * add rsp, 8 // skip eth_type_trans's frame * ret // return to its caller */ int arch_prepare_bpf_trampoline(void *image, void *image_end, const struct btf_func_model *m, u32 flags, struct bpf_prog **fentry_progs, int fentry_cnt, struct bpf_prog **fexit_progs, int fexit_cnt, void *orig_call) { int cnt = 0, nr_args = m->nr_args; int stack_size = nr_args * 8; u8 *prog; /* x86-64 supports up to 6 arguments. 7+ can be added in the future */ if (nr_args > 6) return -ENOTSUPP; if ((flags & BPF_TRAMP_F_RESTORE_REGS) && (flags & BPF_TRAMP_F_SKIP_FRAME)) return -EINVAL; if (flags & BPF_TRAMP_F_CALL_ORIG) stack_size += 8; /* room for return value of orig_call */ if (flags & BPF_TRAMP_F_SKIP_FRAME) /* skip patched call instruction and point orig_call to actual * body of the kernel function. */ orig_call += X86_PATCH_SIZE; prog = image; EMIT1(0x55); /* push rbp */ EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */ EMIT4(0x48, 0x83, 0xEC, stack_size); /* sub rsp, stack_size */ EMIT1(0x53); /* push rbx */ save_regs(m, &prog, nr_args, stack_size); if (fentry_cnt) if (invoke_bpf(m, &prog, fentry_progs, fentry_cnt, stack_size)) return -EINVAL; if (flags & BPF_TRAMP_F_CALL_ORIG) { if (fentry_cnt) restore_regs(m, &prog, nr_args, stack_size); /* call original function */ if (emit_call(&prog, orig_call, prog)) return -EINVAL; /* remember return value in a stack for bpf prog to access */ emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8); } if (fexit_cnt) if (invoke_bpf(m, &prog, fexit_progs, fexit_cnt, stack_size)) return -EINVAL; if (flags & BPF_TRAMP_F_RESTORE_REGS) restore_regs(m, &prog, nr_args, stack_size); if (flags & BPF_TRAMP_F_CALL_ORIG) /* restore original return value back into RAX */ emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, -8); EMIT1(0x5B); /* pop rbx */ EMIT1(0xC9); /* leave */ if (flags & BPF_TRAMP_F_SKIP_FRAME) /* skip our return address and return to parent */ EMIT4(0x48, 0x83, 0xC4, 8); /* add rsp, 8 */ EMIT1(0xC3); /* ret */ /* Make sure the trampoline generation logic doesn't overflow */ if (WARN_ON_ONCE(prog > (u8 *)image_end - BPF_INSN_SAFETY)) return -EFAULT; return prog - (u8 *)image; } static int emit_cond_near_jump(u8 **pprog, void *func, void *ip, u8 jmp_cond) { u8 *prog = *pprog; int cnt = 0; s64 offset; offset = func - (ip + 2 + 4); if (!is_simm32(offset)) { pr_err("Target %p is out of range\n", func); return -EINVAL; } EMIT2_off32(0x0F, jmp_cond + 0x10, offset); *pprog = prog; return 0; } static void emit_nops(u8 **pprog, unsigned int len) { unsigned int i, noplen; u8 *prog = *pprog; int cnt = 0; while (len > 0) { noplen = len; if (noplen > ASM_NOP_MAX) noplen = ASM_NOP_MAX; for (i = 0; i < noplen; i++) EMIT1(ideal_nops[noplen][i]); len -= noplen; } *pprog = prog; } static int emit_fallback_jump(u8 **pprog) { u8 *prog = *pprog; int err = 0; #ifdef CONFIG_RETPOLINE /* Note that this assumes the the compiler uses external * thunks for indirect calls. Both clang and GCC use the same * naming convention for external thunks. */ err = emit_jump(&prog, __x86_indirect_thunk_rdx, prog); #else int cnt = 0; EMIT2(0xFF, 0xE2); /* jmp rdx */ #endif *pprog = prog; return err; } static int emit_bpf_dispatcher(u8 **pprog, int a, int b, s64 *progs) { u8 *jg_reloc, *jg_target, *prog = *pprog; int pivot, err, jg_bytes = 1, cnt = 0; s64 jg_offset; if (a == b) { /* Leaf node of recursion, i.e. not a range of indices * anymore. */ EMIT1(add_1mod(0x48, BPF_REG_3)); /* cmp rdx,func */ if (!is_simm32(progs[a])) return -1; EMIT2_off32(0x81, add_1reg(0xF8, BPF_REG_3), progs[a]); err = emit_cond_near_jump(&prog, /* je func */ (void *)progs[a], prog, X86_JE); if (err) return err; err = emit_fallback_jump(&prog); /* jmp thunk/indirect */ if (err) return err; *pprog = prog; return 0; } /* Not a leaf node, so we pivot, and recursively descend into * the lower and upper ranges. */ pivot = (b - a) / 2; EMIT1(add_1mod(0x48, BPF_REG_3)); /* cmp rdx,func */ if (!is_simm32(progs[a + pivot])) return -1; EMIT2_off32(0x81, add_1reg(0xF8, BPF_REG_3), progs[a + pivot]); if (pivot > 2) { /* jg upper_part */ /* Require near jump. */ jg_bytes = 4; EMIT2_off32(0x0F, X86_JG + 0x10, 0); } else { EMIT2(X86_JG, 0); } jg_reloc = prog; err = emit_bpf_dispatcher(&prog, a, a + pivot, /* emit lower_part */ progs); if (err) return err; /* From Intel 64 and IA-32 Architectures Optimization * Reference Manual, 3.4.1.4 Code Alignment, Assembly/Compiler * Coding Rule 11: All branch targets should be 16-byte * aligned. */ jg_target = PTR_ALIGN(prog, 16); if (jg_target != prog) emit_nops(&prog, jg_target - prog); jg_offset = prog - jg_reloc; emit_code(jg_reloc - jg_bytes, jg_offset, jg_bytes); err = emit_bpf_dispatcher(&prog, a + pivot + 1, /* emit upper_part */ b, progs); if (err) return err; *pprog = prog; return 0; } static int cmp_ips(const void *a, const void *b) { const s64 *ipa = a; const s64 *ipb = b; if (*ipa > *ipb) return 1; if (*ipa < *ipb) return -1; return 0; } int arch_prepare_bpf_dispatcher(void *image, s64 *funcs, int num_funcs) { u8 *prog = image; sort(funcs, num_funcs, sizeof(funcs[0]), cmp_ips, NULL); return emit_bpf_dispatcher(&prog, 0, num_funcs - 1, funcs); } struct x64_jit_data { struct bpf_binary_header *header; int *addrs; u8 *image; int proglen; struct jit_context ctx; }; struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) { struct bpf_binary_header *header = NULL; struct bpf_prog *tmp, *orig_prog = prog; struct x64_jit_data *jit_data; int proglen, oldproglen = 0; struct jit_context ctx = {}; bool tmp_blinded = false; bool extra_pass = false; u8 *image = NULL; int *addrs; int pass; int i; if (!prog->jit_requested) return orig_prog; tmp = bpf_jit_blind_constants(prog); /* * If blinding was requested and we failed during blinding, * we must fall back to the interpreter. */ if (IS_ERR(tmp)) return orig_prog; if (tmp != prog) { tmp_blinded = true; prog = tmp; } jit_data = prog->aux->jit_data; if (!jit_data) { jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL); if (!jit_data) { prog = orig_prog; goto out; } prog->aux->jit_data = jit_data; } addrs = jit_data->addrs; if (addrs) { ctx = jit_data->ctx; oldproglen = jit_data->proglen; image = jit_data->image; header = jit_data->header; extra_pass = true; goto skip_init_addrs; } addrs = kmalloc_array(prog->len + 1, sizeof(*addrs), GFP_KERNEL); if (!addrs) { prog = orig_prog; goto out_addrs; } /* * Before first pass, make a rough estimation of addrs[] * each BPF instruction is translated to less than 64 bytes */ for (proglen = 0, i = 0; i <= prog->len; i++) { proglen += 64; addrs[i] = proglen; } ctx.cleanup_addr = proglen; skip_init_addrs: /* * JITed image shrinks with every pass and the loop iterates * until the image stops shrinking. Very large BPF programs * may converge on the last pass. In such case do one more * pass to emit the final image. */ for (pass = 0; pass < 20 || image; pass++) { proglen = do_jit(prog, addrs, image, oldproglen, &ctx); if (proglen <= 0) { out_image: image = NULL; if (header) bpf_jit_binary_free(header); prog = orig_prog; goto out_addrs; } if (image) { if (proglen != oldproglen) { pr_err("bpf_jit: proglen=%d != oldproglen=%d\n", proglen, oldproglen); goto out_image; } break; } if (proglen == oldproglen) { /* * The number of entries in extable is the number of BPF_LDX * insns that access kernel memory via "pointer to BTF type". * The verifier changed their opcode from LDX|MEM|size * to LDX|PROBE_MEM|size to make JITing easier. */ u32 align = __alignof__(struct exception_table_entry); u32 extable_size = prog->aux->num_exentries * sizeof(struct exception_table_entry); /* allocate module memory for x86 insns and extable */ header = bpf_jit_binary_alloc(roundup(proglen, align) + extable_size, &image, align, jit_fill_hole); if (!header) { prog = orig_prog; goto out_addrs; } prog->aux->extable = (void *) image + roundup(proglen, align); } oldproglen = proglen; cond_resched(); } if (bpf_jit_enable > 1) bpf_jit_dump(prog->len, proglen, pass + 1, image); if (image) { if (!prog->is_func || extra_pass) { bpf_tail_call_direct_fixup(prog); bpf_jit_binary_lock_ro(header); } else { jit_data->addrs = addrs; jit_data->ctx = ctx; jit_data->proglen = proglen; jit_data->image = image; jit_data->header = header; } prog->bpf_func = (void *)image; prog->jited = 1; prog->jited_len = proglen; } else { prog = orig_prog; } if (!image || !prog->is_func || extra_pass) { if (image) bpf_prog_fill_jited_linfo(prog, addrs + 1); out_addrs: kfree(addrs); kfree(jit_data); prog->aux->jit_data = NULL; } out: if (tmp_blinded) bpf_jit_prog_release_other(prog, prog == orig_prog ? tmp : orig_prog); return prog; }