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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#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/* Sign-extended 32-bit immediate load */
55#define PPC_LI32(d, i) do { \
56 if ((int)(uintptr_t)(i) >= -32768 && \
57 (int)(uintptr_t)(i) < 32768) \
58 EMIT(PPC_RAW_LI(d, i)); \
59 else { \
60 EMIT(PPC_RAW_LIS(d, IMM_H(i))); \
61 if (IMM_L(i)) \
62 EMIT(PPC_RAW_ORI(d, d, IMM_L(i))); \
63 } } while(0)
64
65#ifdef CONFIG_PPC64
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#define PPC_LI_ADDR PPC_LI64
89
90#ifndef CONFIG_PPC_KERNEL_PCREL
91#define PPC64_LOAD_PACA() \
92 EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc)))
93#else
94#define PPC64_LOAD_PACA() do {} while (0)
95#endif
96#else
97#define PPC_LI64(d, i) BUILD_BUG()
98#define PPC_LI_ADDR PPC_LI32
99#define PPC64_LOAD_PACA() BUILD_BUG()
100#endif
101
102/*
103 * The fly in the ointment of code size changing from pass to pass is
104 * avoided by padding the short branch case with a NOP. If code size differs
105 * with different branch reaches we will have the issue of code moving from
106 * one pass to the next and will need a few passes to converge on a stable
107 * state.
108 */
109#define PPC_BCC(cond, dest) do { \
110 if (is_offset_in_cond_branch_range((long)(dest) - CTX_NIA(ctx))) { \
111 PPC_BCC_SHORT(cond, dest); \
112 EMIT(PPC_RAW_NOP()); \
113 } else { \
114 /* Flip the 'T or F' bit to invert comparison */ \
115 PPC_BCC_SHORT(cond ^ COND_CMP_TRUE, CTX_NIA(ctx) + 2*4); \
116 PPC_JMP(dest); \
117 } } while(0)
118
119/* To create a branch condition, select a bit of cr0... */
120#define CR0_LT 0
121#define CR0_GT 1
122#define CR0_EQ 2
123/* ...and modify BO[3] */
124#define COND_CMP_TRUE 0x100
125#define COND_CMP_FALSE 0x000
126/* Together, they make all required comparisons: */
127#define COND_GT (CR0_GT | COND_CMP_TRUE)
128#define COND_GE (CR0_LT | COND_CMP_FALSE)
129#define COND_EQ (CR0_EQ | COND_CMP_TRUE)
130#define COND_NE (CR0_EQ | COND_CMP_FALSE)
131#define COND_LT (CR0_LT | COND_CMP_TRUE)
132#define COND_LE (CR0_GT | COND_CMP_FALSE)
133
134#define SEEN_FUNC 0x20000000 /* might call external helpers */
135#define SEEN_TAILCALL 0x40000000 /* uses tail calls */
136
137struct codegen_context {
138 /*
139 * This is used to track register usage as well
140 * as calls to external helpers.
141 * - register usage is tracked with corresponding
142 * bits (r3-r31)
143 * - rest of the bits can be used to track other
144 * things -- for now, we use bits 0 to 2
145 * encoded in SEEN_* macros above
146 */
147 unsigned int seen;
148 unsigned int idx;
149 unsigned int stack_size;
150 int b2p[MAX_BPF_JIT_REG + 2];
151 unsigned int exentry_idx;
152 unsigned int alt_exit_addr;
153};
154
155#define bpf_to_ppc(r) (ctx->b2p[r])
156
157#ifdef CONFIG_PPC32
158#define BPF_FIXUP_LEN 3 /* Three instructions => 12 bytes */
159#else
160#define BPF_FIXUP_LEN 2 /* Two instructions => 8 bytes */
161#endif
162
163static inline bool bpf_is_seen_register(struct codegen_context *ctx, int i)
164{
165 return ctx->seen & (1 << (31 - i));
166}
167
168static inline void bpf_set_seen_register(struct codegen_context *ctx, int i)
169{
170 ctx->seen |= 1 << (31 - i);
171}
172
173static inline void bpf_clear_seen_register(struct codegen_context *ctx, int i)
174{
175 ctx->seen &= ~(1 << (31 - i));
176}
177
178void bpf_jit_init_reg_mapping(struct codegen_context *ctx);
179int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context *ctx, u64 func);
180int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct codegen_context *ctx,
181 u32 *addrs, int pass, bool extra_pass);
182void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx);
183void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx);
184void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx);
185void bpf_jit_realloc_regs(struct codegen_context *ctx);
186int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr);
187
188int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass,
189 struct codegen_context *ctx, int insn_idx,
190 int jmp_off, int dst_reg);
191
192#endif
193
194#endif