arch/powerpc/net/bpf_jit.h

   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 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 ((dest) != 0 && !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_RAW_BRANCH(offset));                                 \
  35         } while (0)
  36
  37 /* bl (unconditional 'branch' with link) */
  38 #define PPC_BL(dest)    EMIT(PPC_RAW_BL((dest) - (unsigned long)(image + ctx->idx)))
  39
  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 ((dest) != 0 && !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_PPC64
  63 #define PPC_LI64(d, i)          do {                                          \
  64                 if ((long)(i) >= -2147483648 &&                               \
  65                                 (long)(i) < 2147483648)                       \
  66                         PPC_LI32(d, i);                                       \
  67                 else {                                                        \
  68                         if (!((uintptr_t)(i) & 0xffff800000000000ULL))        \
  69                                 EMIT(PPC_RAW_LI(d, ((uintptr_t)(i) >> 32) &   \
  70                                                 0xffff));                     \
  71                         else {                                                \
  72                                 EMIT(PPC_RAW_LIS(d, ((uintptr_t)(i) >> 48))); \
  73                                 if ((uintptr_t)(i) & 0x0000ffff00000000ULL)   \
  74                                         EMIT(PPC_RAW_ORI(d, d,                \
  75                                           ((uintptr_t)(i) >> 32) & 0xffff));  \
  76                         }                                                     \
  77                         EMIT(PPC_RAW_SLDI(d, d, 32));                         \
  78                         if ((uintptr_t)(i) & 0x00000000ffff0000ULL)           \
  79                                 EMIT(PPC_RAW_ORIS(d, d,                       \
  80                                          ((uintptr_t)(i) >> 16) & 0xffff));   \
  81                         if ((uintptr_t)(i) & 0x000000000000ffffULL)           \
  82                                 EMIT(PPC_RAW_ORI(d, d, (uintptr_t)(i) &       \
  83                                                         0xffff));             \
  84                 } } while (0)
  85 #endif
  86
  87 /*
  88  * The fly in the ointment of code size changing from pass to pass is
  89  * avoided by padding the short branch case with a NOP.  If code size differs
  90  * with different branch reaches we will have the issue of code moving from
  91  * one pass to the next and will need a few passes to converge on a stable
  92  * state.
  93  */
  94 #define PPC_BCC(cond, dest)     do {                                          \
  95                 if (is_offset_in_cond_branch_range((long)(dest) - (ctx->idx * 4))) {    \
  96                         PPC_BCC_SHORT(cond, dest);                            \
  97                         EMIT(PPC_RAW_NOP());                                  \
  98                 } else {                                                      \
  99                         /* Flip the 'T or F' bit to invert comparison */      \
 100                         PPC_BCC_SHORT(cond ^ COND_CMP_TRUE, (ctx->idx+2)*4);  \
 101                         PPC_JMP(dest);                                        \
 102                 } } while(0)
 103
 104 /* To create a branch condition, select a bit of cr0... */
 105 #define CR0_LT          0
 106 #define CR0_GT          1
 107 #define CR0_EQ          2
 108 /* ...and modify BO[3] */
 109 #define COND_CMP_TRUE   0x100
 110 #define COND_CMP_FALSE  0x000
 111 /* Together, they make all required comparisons: */
 112 #define COND_GT         (CR0_GT | COND_CMP_TRUE)
 113 #define COND_GE         (CR0_LT | COND_CMP_FALSE)
 114 #define COND_EQ         (CR0_EQ | COND_CMP_TRUE)
 115 #define COND_NE         (CR0_EQ | COND_CMP_FALSE)
 116 #define COND_LT         (CR0_LT | COND_CMP_TRUE)
 117 #define COND_LE         (CR0_GT | COND_CMP_FALSE)
 118
 119 #define SEEN_FUNC       0x20000000 /* might call external helpers */
 120 #define SEEN_TAILCALL   0x40000000 /* uses tail calls */
 121
 122 struct codegen_context {
 123         /*
 124          * This is used to track register usage as well
 125          * as calls to external helpers.
 126          * - register usage is tracked with corresponding
 127          *   bits (r3-r31)
 128          * - rest of the bits can be used to track other
 129          *   things -- for now, we use bits 0 to 2
 130          *   encoded in SEEN_* macros above
 131          */
 132         unsigned int seen;
 133         unsigned int idx;
 134         unsigned int stack_size;
 135         int b2p[MAX_BPF_JIT_REG + 2];
 136         unsigned int exentry_idx;
 137         unsigned int alt_exit_addr;
 138 };
 139
 140 #define bpf_to_ppc(r)   (ctx->b2p[r])
 141
 142 #ifdef CONFIG_PPC32
 143 #define BPF_FIXUP_LEN   3 /* Three instructions => 12 bytes */
 144 #else
 145 #define BPF_FIXUP_LEN   2 /* Two instructions => 8 bytes */
 146 #endif
 147
 148 static inline void bpf_flush_icache(void *start, void *end)
 149 {
 150         smp_wmb();      /* smp write barrier */
 151         flush_icache_range((unsigned long)start, (unsigned long)end);
 152 }
 153
 154 static inline bool bpf_is_seen_register(struct codegen_context *ctx, int i)
 155 {
 156         return ctx->seen & (1 << (31 - i));
 157 }
 158
 159 static inline void bpf_set_seen_register(struct codegen_context *ctx, int i)
 160 {
 161         ctx->seen |= 1 << (31 - i);
 162 }
 163
 164 static inline void bpf_clear_seen_register(struct codegen_context *ctx, int i)
 165 {
 166         ctx->seen &= ~(1 << (31 - i));
 167 }
 168
 169 void bpf_jit_init_reg_mapping(struct codegen_context *ctx);
 170 int bpf_jit_emit_func_call_rel(u32 *image, struct codegen_context *ctx, u64 func);
 171 int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *ctx,
 172                        u32 *addrs, int pass, bool extra_pass);
 173 void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx);
 174 void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx);
 175 void bpf_jit_realloc_regs(struct codegen_context *ctx);
 176 int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr);
 177
 178 int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, int pass, struct codegen_context *ctx,
 179                           int insn_idx, int jmp_off, int dst_reg);
 180
 181 #endif
 182
 183 #endif