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