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 <[email protected]>, IBM Corporation
   6  *           2016 Naveen N. Rao <[email protected]>
   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
 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
 162 static inline bool bpf_is_seen_register(struct codegen_context *ctx, int i)
 163 {
 164         return ctx->seen & (1 << (31 - i));
 165 }
 166
 167 static inline void bpf_set_seen_register(struct codegen_context *ctx, int i)
 168 {
 169         ctx->seen |= 1 << (31 - i);
 170 }
 171
 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