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 __ASSEMBLY__
12
13 #include <asm/types.h>
14 #include <asm/ppc-opcode.h>
15
16 #ifdef PPC64_ELF_ABI_v1
17 #define FUNCTION_DESCR_SIZE 24
18 #else
19 #define FUNCTION_DESCR_SIZE 0
20 #endif
21
22 #define PLANT_INSTR(d, idx, instr) \
23 do { if (d) { (d)[idx] = instr; } idx++; } while (0)
24 #define EMIT(instr) PLANT_INSTR(image, ctx->idx, instr)
25
26 /* Long jump; (unconditional 'branch') */
27 #define PPC_JMP(dest) \
28 do { \
29 long offset = (long)(dest) - (ctx->idx * 4); \
30 if (!is_offset_in_branch_range(offset)) { \
31 pr_err_ratelimited("Branch offset 0x%lx (@%u) out of range\n", offset, ctx->idx); \
32 return -ERANGE; \
33 } \
34 EMIT(PPC_INST_BRANCH | (offset & 0x03fffffc)); \
35 } while (0)
36
37 /* blr; (unconditional 'branch' with link) to absolute address */
38 #define PPC_BL_ABS(dest) EMIT(PPC_INST_BL | \
39 (((dest) - (unsigned long)(image + ctx->idx)) & 0x03fffffc))
40 /* "cond" here covers BO:BI fields. */
41 #define PPC_BCC_SHORT(cond, dest) \
42 do { \
43 long offset = (long)(dest) - (ctx->idx * 4); \
44 if (!is_offset_in_cond_branch_range(offset)) { \
45 pr_err_ratelimited("Conditional branch offset 0x%lx (@%u) out of range\n", offset, ctx->idx); \
46 return -ERANGE; \
47 } \
48 EMIT(PPC_INST_BRANCH_COND | (((cond) & 0x3ff) << 16) | (offset & 0xfffc)); \
49 } while (0)
50
51 /* Sign-extended 32-bit immediate load */
52 #define PPC_LI32(d, i) do { \
53 if ((int)(uintptr_t)(i) >= -32768 && \
54 (int)(uintptr_t)(i) < 32768) \
55 EMIT(PPC_RAW_LI(d, i)); \
56 else { \
57 EMIT(PPC_RAW_LIS(d, IMM_H(i))); \
58 if (IMM_L(i)) \
59 EMIT(PPC_RAW_ORI(d, d, IMM_L(i))); \
60 } } while(0)
61
62 #ifdef CONFIG_PPC32
63 #define PPC_EX32(r, i) EMIT(PPC_RAW_LI((r), (i) < 0 ? -1 : 0))
64 #endif
65
66 #define PPC_LI64(d, i) do { \
67 if ((long)(i) >= -2147483648 && \
68 (long)(i) < 2147483648) \
69 PPC_LI32(d, i); \
70 else { \
71 if (!((uintptr_t)(i) & 0xffff800000000000ULL)) \
72 EMIT(PPC_RAW_LI(d, ((uintptr_t)(i) >> 32) & \
73 0xffff)); \
74 else { \
75 EMIT(PPC_RAW_LIS(d, ((uintptr_t)(i) >> 48))); \
76 if ((uintptr_t)(i) & 0x0000ffff00000000ULL) \
77 EMIT(PPC_RAW_ORI(d, d, \
78 ((uintptr_t)(i) >> 32) & 0xffff)); \
79 } \
80 EMIT(PPC_RAW_SLDI(d, d, 32)); \
81 if ((uintptr_t)(i) & 0x00000000ffff0000ULL) \
82 EMIT(PPC_RAW_ORIS(d, d, \
83 ((uintptr_t)(i) >> 16) & 0xffff)); \
84 if ((uintptr_t)(i) & 0x000000000000ffffULL) \
85 EMIT(PPC_RAW_ORI(d, d, (uintptr_t)(i) & \
86 0xffff)); \
87 } } while (0)
88
89 #ifdef CONFIG_PPC64
90 #define PPC_FUNC_ADDR(d,i) do { PPC_LI64(d, i); } while(0)
91 #else
92 #define PPC_FUNC_ADDR(d,i) do { PPC_LI32(d, i); } while(0)
93 #endif
94
95 /*
96 * The fly in the ointment of code size changing from pass to pass is
97 * avoided by padding the short branch case with a NOP. If code size differs
98 * with different branch reaches we will have the issue of code moving from
99 * one pass to the next and will need a few passes to converge on a stable
100 * state.
101 */
102 #define PPC_BCC(cond, dest) do { \
103 if (is_offset_in_cond_branch_range((long)(dest) - (ctx->idx * 4))) { \
104 PPC_BCC_SHORT(cond, dest); \
105 EMIT(PPC_RAW_NOP()); \
106 } else { \
107 /* Flip the 'T or F' bit to invert comparison */ \
108 PPC_BCC_SHORT(cond ^ COND_CMP_TRUE, (ctx->idx+2)*4); \
109 PPC_JMP(dest); \
110 } } while(0)
111
112 /* To create a branch condition, select a bit of cr0... */
113 #define CR0_LT 0
114 #define CR0_GT 1
115 #define CR0_EQ 2
116 /* ...and modify BO[3] */
117 #define COND_CMP_TRUE 0x100
118 #define COND_CMP_FALSE 0x000
119 /* Together, they make all required comparisons: */
120 #define COND_GT (CR0_GT | COND_CMP_TRUE)
121 #define COND_GE (CR0_LT | COND_CMP_FALSE)
122 #define COND_EQ (CR0_EQ | COND_CMP_TRUE)
123 #define COND_NE (CR0_EQ | COND_CMP_FALSE)
124 #define COND_LT (CR0_LT | COND_CMP_TRUE)
125 #define COND_LE (CR0_GT | COND_CMP_FALSE)
126
127 #define SEEN_FUNC 0x20000000 /* might call external helpers */
128 #define SEEN_STACK 0x40000000 /* uses BPF stack */
129 #define SEEN_TAILCALL 0x80000000 /* uses tail calls */
130
131 #define SEEN_VREG_MASK 0x1ff80000 /* Volatile registers r3-r12 */
132 #define SEEN_NVREG_MASK 0x0003ffff /* Non volatile registers r14-r31 */
133
134 #ifdef CONFIG_PPC64
135 extern const int b2p[MAX_BPF_JIT_REG + 2];
136 #else
137 extern const int b2p[MAX_BPF_JIT_REG + 1];
138 #endif
139
140 struct codegen_context {
141 /*
142 * This is used to track register usage as well
143 * as calls to external helpers.
144 * - register usage is tracked with corresponding
145 * bits (r3-r31)
146 * - rest of the bits can be used to track other
147 * things -- for now, we use bits 0 to 2
148 * encoded in SEEN_* macros above
149 */
150 unsigned int seen;
151 unsigned int idx;
152 unsigned int stack_size;
153 int b2p[ARRAY_SIZE(b2p)];
154 };
155
bpf_flush_icache(void * start,void * end)156 static inline void bpf_flush_icache(void *start, void *end)
157 {
158 smp_wmb(); /* smp write barrier */
159 flush_icache_range((unsigned long)start, (unsigned long)end);
160 }
161
bpf_is_seen_register(struct codegen_context * ctx,int i)162 static inline bool bpf_is_seen_register(struct codegen_context *ctx, int i)
163 {
164 return ctx->seen & (1 << (31 - i));
165 }
166
bpf_set_seen_register(struct codegen_context * ctx,int i)167 static inline void bpf_set_seen_register(struct codegen_context *ctx, int i)
168 {
169 ctx->seen |= 1 << (31 - i);
170 }
171
bpf_clear_seen_register(struct codegen_context * ctx,int i)172 static inline void bpf_clear_seen_register(struct codegen_context *ctx, int i)
173 {
174 ctx->seen &= ~(1 << (31 - i));
175 }
176
177 void bpf_jit_emit_func_call_rel(u32 *image, struct codegen_context *ctx, u64 func);
178 int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *ctx,
179 u32 *addrs, bool extra_pass);
180 void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx);
181 void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx);
182 void bpf_jit_realloc_regs(struct codegen_context *ctx);
183
184 #endif
185
186 #endif
187