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Diffstat (limited to 'arch/mips/net/bpf_jit_comp.h')
| -rw-r--r-- | arch/mips/net/bpf_jit_comp.h | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/arch/mips/net/bpf_jit_comp.h b/arch/mips/net/bpf_jit_comp.h new file mode 100644 index 000000000..a37fe2081 --- /dev/null +++ b/arch/mips/net/bpf_jit_comp.h @@ -0,0 +1,235 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Just-In-Time compiler for eBPF bytecode on 32-bit and 64-bit MIPS. + * + * Copyright (c) 2021 Anyfi Networks AB. + * Author: Johan Almbladh <johan.almbladh@gmail.com> + * + * Based on code and ideas from + * Copyright (c) 2017 Cavium, Inc. + * Copyright (c) 2017 Shubham Bansal <illusionist.neo@gmail.com> + * Copyright (c) 2011 Mircea Gherzan <mgherzan@gmail.com> + */ + +#ifndef _BPF_JIT_COMP_H +#define _BPF_JIT_COMP_H + +/* MIPS registers */ +#define MIPS_R_ZERO 0 /* Const zero */ +#define MIPS_R_AT 1 /* Asm temp */ +#define MIPS_R_V0 2 /* Result */ +#define MIPS_R_V1 3 /* Result */ +#define MIPS_R_A0 4 /* Argument */ +#define MIPS_R_A1 5 /* Argument */ +#define MIPS_R_A2 6 /* Argument */ +#define MIPS_R_A3 7 /* Argument */ +#define MIPS_R_A4 8 /* Arg (n64) */ +#define MIPS_R_A5 9 /* Arg (n64) */ +#define MIPS_R_A6 10 /* Arg (n64) */ +#define MIPS_R_A7 11 /* Arg (n64) */ +#define MIPS_R_T0 8 /* Temp (o32) */ +#define MIPS_R_T1 9 /* Temp (o32) */ +#define MIPS_R_T2 10 /* Temp (o32) */ +#define MIPS_R_T3 11 /* Temp (o32) */ +#define MIPS_R_T4 12 /* Temporary */ +#define MIPS_R_T5 13 /* Temporary */ +#define MIPS_R_T6 14 /* Temporary */ +#define MIPS_R_T7 15 /* Temporary */ +#define MIPS_R_S0 16 /* Saved */ +#define MIPS_R_S1 17 /* Saved */ +#define MIPS_R_S2 18 /* Saved */ +#define MIPS_R_S3 19 /* Saved */ +#define MIPS_R_S4 20 /* Saved */ +#define MIPS_R_S5 21 /* Saved */ +#define MIPS_R_S6 22 /* Saved */ +#define MIPS_R_S7 23 /* Saved */ +#define MIPS_R_T8 24 /* Temporary */ +#define MIPS_R_T9 25 /* Temporary */ +/* MIPS_R_K0 26 Reserved */ +/* MIPS_R_K1 27 Reserved */ +#define MIPS_R_GP 28 /* Global ptr */ +#define MIPS_R_SP 29 /* Stack ptr */ +#define MIPS_R_FP 30 /* Frame ptr */ +#define MIPS_R_RA 31 /* Return */ + +/* + * Jump address mask for immediate jumps. The four most significant bits + * must be equal to PC. + */ +#define MIPS_JMP_MASK 0x0fffffffUL + +/* Maximum number of iterations in offset table computation */ +#define JIT_MAX_ITERATIONS 8 + +/* + * Jump pseudo-instructions used internally + * for branch conversion and branch optimization. + */ +#define JIT_JNSET 0xe0 +#define JIT_JNOP 0xf0 + +/* Descriptor flag for PC-relative branch conversion */ +#define JIT_DESC_CONVERT BIT(31) + +/* JIT context for an eBPF program */ +struct jit_context { + struct bpf_prog *program; /* The eBPF program being JITed */ + u32 *descriptors; /* eBPF to JITed CPU insn descriptors */ + u32 *target; /* JITed code buffer */ + u32 bpf_index; /* Index of current BPF program insn */ + u32 jit_index; /* Index of current JIT target insn */ + u32 changes; /* Number of PC-relative branch conv */ + u32 accessed; /* Bit mask of read eBPF registers */ + u32 clobbered; /* Bit mask of modified CPU registers */ + u32 stack_size; /* Total allocated stack size in bytes */ + u32 saved_size; /* Size of callee-saved registers */ + u32 stack_used; /* Stack size used for function calls */ +}; + +/* Emit the instruction if the JIT memory space has been allocated */ +#define __emit(ctx, func, ...) \ +do { \ + if ((ctx)->target != NULL) { \ + u32 *p = &(ctx)->target[ctx->jit_index]; \ + uasm_i_##func(&p, ##__VA_ARGS__); \ + } \ + (ctx)->jit_index++; \ +} while (0) +#define emit(...) __emit(__VA_ARGS__) + +/* Workaround for R10000 ll/sc errata */ +#ifdef CONFIG_WAR_R10000_LLSC +#define LLSC_beqz beqzl +#else +#define LLSC_beqz beqz +#endif + +/* Workaround for Loongson-3 ll/sc errata */ +#ifdef CONFIG_CPU_LOONGSON3_WORKAROUNDS +#define LLSC_sync(ctx) emit(ctx, sync, 0) +#define LLSC_offset 4 +#else +#define LLSC_sync(ctx) +#define LLSC_offset 0 +#endif + +/* Workaround for Loongson-2F jump errata */ +#ifdef CONFIG_CPU_JUMP_WORKAROUNDS +#define JALR_MASK 0xffffffffcfffffffULL +#else +#define JALR_MASK (~0ULL) +#endif + +/* + * Mark a BPF register as accessed, it needs to be + * initialized by the program if expected, e.g. FP. + */ +static inline void access_reg(struct jit_context *ctx, u8 reg) +{ + ctx->accessed |= BIT(reg); +} + +/* + * Mark a CPU register as clobbered, it needs to be + * saved/restored by the program if callee-saved. + */ +static inline void clobber_reg(struct jit_context *ctx, u8 reg) +{ + ctx->clobbered |= BIT(reg); +} + +/* + * Push registers on the stack, starting at a given depth from the stack + * pointer and increasing. The next depth to be written is returned. + */ +int push_regs(struct jit_context *ctx, u32 mask, u32 excl, int depth); + +/* + * Pop registers from the stack, starting at a given depth from the stack + * pointer and increasing. The next depth to be read is returned. + */ +int pop_regs(struct jit_context *ctx, u32 mask, u32 excl, int depth); + +/* Compute the 28-bit jump target address from a BPF program location */ +int get_target(struct jit_context *ctx, u32 loc); + +/* Compute the PC-relative offset to relative BPF program offset */ +int get_offset(const struct jit_context *ctx, int off); + +/* dst = imm (32-bit) */ +void emit_mov_i(struct jit_context *ctx, u8 dst, s32 imm); + +/* dst = src (32-bit) */ +void emit_mov_r(struct jit_context *ctx, u8 dst, u8 src); + +/* Validate ALU/ALU64 immediate range */ +bool valid_alu_i(u8 op, s32 imm); + +/* Rewrite ALU/ALU64 immediate operation */ +bool rewrite_alu_i(u8 op, s32 imm, u8 *alu, s32 *val); + +/* ALU immediate operation (32-bit) */ +void emit_alu_i(struct jit_context *ctx, u8 dst, s32 imm, u8 op); + +/* ALU register operation (32-bit) */ +void emit_alu_r(struct jit_context *ctx, u8 dst, u8 src, u8 op); + +/* Atomic read-modify-write (32-bit) */ +void emit_atomic_r(struct jit_context *ctx, u8 dst, u8 src, s16 off, u8 code); + +/* Atomic compare-and-exchange (32-bit) */ +void emit_cmpxchg_r(struct jit_context *ctx, u8 dst, u8 src, u8 res, s16 off); + +/* Swap bytes and truncate a register word or half word */ +void emit_bswap_r(struct jit_context *ctx, u8 dst, u32 width); + +/* Validate JMP/JMP32 immediate range */ +bool valid_jmp_i(u8 op, s32 imm); + +/* Prepare a PC-relative jump operation with immediate conditional */ +void setup_jmp_i(struct jit_context *ctx, s32 imm, u8 width, + u8 bpf_op, s16 bpf_off, u8 *jit_op, s32 *jit_off); + +/* Prepare a PC-relative jump operation with register conditional */ +void setup_jmp_r(struct jit_context *ctx, bool same_reg, + u8 bpf_op, s16 bpf_off, u8 *jit_op, s32 *jit_off); + +/* Finish a PC-relative jump operation */ +int finish_jmp(struct jit_context *ctx, u8 jit_op, s16 bpf_off); + +/* Conditional JMP/JMP32 immediate */ +void emit_jmp_i(struct jit_context *ctx, u8 dst, s32 imm, s32 off, u8 op); + +/* Conditional JMP/JMP32 register */ +void emit_jmp_r(struct jit_context *ctx, u8 dst, u8 src, s32 off, u8 op); + +/* Jump always */ +int emit_ja(struct jit_context *ctx, s16 off); + +/* Jump to epilogue */ +int emit_exit(struct jit_context *ctx); + +/* + * Build program prologue to set up the stack and registers. + * This function is implemented separately for 32-bit and 64-bit JITs. + */ +void build_prologue(struct jit_context *ctx); + +/* + * Build the program epilogue to restore the stack and registers. + * This function is implemented separately for 32-bit and 64-bit JITs. + */ +void build_epilogue(struct jit_context *ctx, int dest_reg); + +/* + * Convert an eBPF instruction to native instruction, i.e + * JITs an eBPF instruction. + * Returns : + * 0 - Successfully JITed an 8-byte eBPF instruction + * >0 - Successfully JITed a 16-byte eBPF instruction + * <0 - Failed to JIT. + * This function is implemented separately for 32-bit and 64-bit JITs. + */ +int build_insn(const struct bpf_insn *insn, struct jit_context *ctx); + +#endif /* _BPF_JIT_COMP_H */ |