1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * bpf_jit.h: BPF JIT compiler for PPC
4 *
5 * Copyright 2011 Matt Evans <matt@ozlabs.org>, IBM Corporation
6 * 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
7 */
8 #ifndef _BPF_JIT_H
9 #define _BPF_JIT_H
10
11 #ifndef __ASSEMBLER__
12
13 #include <asm/types.h>
14 #include <asm/ppc-opcode.h>
15 #include <linux/build_bug.h>
16
17 #ifdef CONFIG_PPC64_ELF_ABI_V1
18 #define FUNCTION_DESCR_SIZE 24
19 #else
20 #define FUNCTION_DESCR_SIZE 0
21 #endif
22
23 #define CTX_NIA(ctx) ((unsigned long)ctx->idx * 4)
24
25 #define SZL sizeof(unsigned long)
26 #define BPF_INSN_SAFETY 64
27
28 #define PLANT_INSTR(d, idx, instr) \
29 do { if (d) { (d)[idx] = instr; } idx++; } while (0)
30 #define EMIT(instr) PLANT_INSTR(image, ctx->idx, instr)
31
32 /* Long jump; (unconditional 'branch') */
33 #define PPC_JMP(dest) \
34 do { \
35 long offset = (long)(dest) - CTX_NIA(ctx); \
36 if ((dest) != 0 && !is_offset_in_branch_range(offset)) { \
37 pr_err_ratelimited("Branch offset 0x%lx (@%u) out of range\n", offset, ctx->idx); \
38 return -ERANGE; \
39 } \
40 EMIT(PPC_RAW_BRANCH(offset)); \
41 } while (0)
42
43 /* "cond" here covers BO:BI fields. */
44 #define PPC_BCC_SHORT(cond, dest) \
45 do { \
46 long offset = (long)(dest) - CTX_NIA(ctx); \
47 if ((dest) != 0 && !is_offset_in_cond_branch_range(offset)) { \
48 pr_err_ratelimited("Conditional branch offset 0x%lx (@%u) out of range\n", offset, ctx->idx); \
49 return -ERANGE; \
50 } \
51 EMIT(PPC_INST_BRANCH_COND | (((cond) & 0x3ff) << 16) | (offset & 0xfffc)); \
52 } while (0)
53
54 /*
55 * Sign-extended 32-bit immediate load
56 *
57 * If this is a dummy pass (!image), account for
58 * maximum possible instructions.
59 */
60 #define PPC_LI32(d, i) do { \
61 if (!image) \
62 ctx->idx += 2; \
63 else { \
64 if ((int)(uintptr_t)(i) >= -32768 && \
65 (int)(uintptr_t)(i) < 32768) \
66 EMIT(PPC_RAW_LI(d, i)); \
67 else { \
68 EMIT(PPC_RAW_LIS(d, IMM_H(i))); \
69 if (IMM_L(i)) \
70 EMIT(PPC_RAW_ORI(d, d, IMM_L(i))); \
71 } \
72 } } while (0)
73
74 #ifdef CONFIG_PPC64
75 /* If dummy pass (!image), account for maximum possible instructions */
76 #define PPC_LI64(d, i) do { \
77 if (!image) \
78 ctx->idx += 5; \
79 else { \
80 if ((long)(i) >= -2147483648 && \
81 (long)(i) < 2147483648) \
82 PPC_LI32(d, i); \
83 else { \
84 if (!((uintptr_t)(i) & 0xffff800000000000ULL)) \
85 EMIT(PPC_RAW_LI(d, ((uintptr_t)(i) >> 32) & \
86 0xffff)); \
87 else { \
88 EMIT(PPC_RAW_LIS(d, ((uintptr_t)(i) >> 48))); \
89 if ((uintptr_t)(i) & 0x0000ffff00000000ULL) \
90 EMIT(PPC_RAW_ORI(d, d, \
91 ((uintptr_t)(i) >> 32) & 0xffff)); \
92 } \
93 EMIT(PPC_RAW_SLDI(d, d, 32)); \
94 if ((uintptr_t)(i) & 0x00000000ffff0000ULL) \
95 EMIT(PPC_RAW_ORIS(d, d, \
96 ((uintptr_t)(i) >> 16) & 0xffff)); \
97 if ((uintptr_t)(i) & 0x000000000000ffffULL) \
98 EMIT(PPC_RAW_ORI(d, d, (uintptr_t)(i) & \
99 0xffff)); \
100 } \
101 } } while (0)
102 #define PPC_LI_ADDR PPC_LI64
103
104 #ifndef CONFIG_PPC_KERNEL_PCREL
105 #define PPC64_LOAD_PACA() \
106 EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc)))
107 #else
108 #define PPC64_LOAD_PACA() do {} while (0)
109 #endif
110 #else
111 #define PPC_LI64(d, i) BUILD_BUG()
112 #define PPC_LI_ADDR PPC_LI32
113 #define PPC64_LOAD_PACA() BUILD_BUG()
114 #endif
115
116 /*
117 * The fly in the ointment of code size changing from pass to pass is
118 * avoided by padding the short branch case with a NOP. If code size differs
119 * with different branch reaches we will have the issue of code moving from
120 * one pass to the next and will need a few passes to converge on a stable
121 * state.
122 */
123 #define PPC_BCC(cond, dest) do { \
124 if (is_offset_in_cond_branch_range((long)(dest) - CTX_NIA(ctx))) { \
125 PPC_BCC_SHORT(cond, dest); \
126 EMIT(PPC_RAW_NOP()); \
127 } else { \
128 /* Flip the 'T or F' bit to invert comparison */ \
129 PPC_BCC_SHORT(cond ^ COND_CMP_TRUE, CTX_NIA(ctx) + 2*4); \
130 PPC_JMP(dest); \
131 } } while(0)
132
133 /* To create a branch condition, select a bit of cr0... */
134 #define CR0_LT 0
135 #define CR0_GT 1
136 #define CR0_EQ 2
137 /* ...and modify BO[3] */
138 #define COND_CMP_TRUE 0x100
139 #define COND_CMP_FALSE 0x000
140 /* Together, they make all required comparisons: */
141 #define COND_GT (CR0_GT | COND_CMP_TRUE)
142 #define COND_GE (CR0_LT | COND_CMP_FALSE)
143 #define COND_EQ (CR0_EQ | COND_CMP_TRUE)
144 #define COND_NE (CR0_EQ | COND_CMP_FALSE)
145 #define COND_LT (CR0_LT | COND_CMP_TRUE)
146 #define COND_LE (CR0_GT | COND_CMP_FALSE)
147
148 #define SEEN_FUNC 0x20000000 /* might call external helpers */
149 #define SEEN_TAILCALL 0x40000000 /* uses tail calls */
150
151 struct codegen_context {
152 /*
153 * This is used to track register usage as well
154 * as calls to external helpers.
155 * - register usage is tracked with corresponding
156 * bits (r3-r31)
157 * - rest of the bits can be used to track other
158 * things -- for now, we use bits 0 to 2
159 * encoded in SEEN_* macros above
160 */
161 unsigned int seen;
162 unsigned int idx;
163 unsigned int stack_size;
164 int b2p[MAX_BPF_JIT_REG + 3];
165 unsigned int exentry_idx;
166 unsigned int alt_exit_addr;
167 u64 arena_vm_start;
168 u64 user_vm_start;
169 };
170
171 #define bpf_to_ppc(r) (ctx->b2p[r])
172
173 #ifdef CONFIG_PPC32
174 #define BPF_FIXUP_LEN 3 /* Three instructions => 12 bytes */
175 #else
176 #define BPF_FIXUP_LEN 2 /* Two instructions => 8 bytes */
177 #endif
178
bpf_is_seen_register(struct codegen_context * ctx,int i)179 static inline bool bpf_is_seen_register(struct codegen_context *ctx, int i)
180 {
181 return ctx->seen & (1 << (31 - i));
182 }
183
bpf_set_seen_register(struct codegen_context * ctx,int i)184 static inline void bpf_set_seen_register(struct codegen_context *ctx, int i)
185 {
186 ctx->seen |= 1 << (31 - i);
187 }
188
bpf_clear_seen_register(struct codegen_context * ctx,int i)189 static inline void bpf_clear_seen_register(struct codegen_context *ctx, int i)
190 {
191 ctx->seen &= ~(1 << (31 - i));
192 }
193
194 void bpf_jit_init_reg_mapping(struct codegen_context *ctx);
195 int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context *ctx, u64 func);
196 int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct codegen_context *ctx,
197 u32 *addrs, int pass, bool extra_pass);
198 void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx);
199 void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx);
200 void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx);
201 void bpf_jit_realloc_regs(struct codegen_context *ctx);
202 int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr);
203
204 int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass,
205 struct codegen_context *ctx, int insn_idx,
206 int jmp_off, int dst_reg, u32 code);
207
208 #endif
209
210 #endif
211