1 /* libffi support for Altera Nios II. 2 3 Copyright (c) 2013 Mentor Graphics. 4 5 Permission is hereby granted, free of charge, to any person obtaining 6 a copy of this software and associated documentation files (the 7 ``Software''), to deal in the Software without restriction, including 8 without limitation the rights to use, copy, modify, merge, publish, 9 distribute, sublicense, and/or sell copies of the Software, and to 10 permit persons to whom the Software is furnished to do so, subject to 11 the following conditions: 12 13 The above copyright notice and this permission notice shall be 14 included in all copies or substantial portions of the Software. 15 16 THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND, 17 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 18 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 19 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 20 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 21 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE 22 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ 23 24 25 #include <ffi.h> 26 #include <ffi_common.h> 27 28 #include <stdlib.h> 29 30 /* The Nios II Processor Reference Handbook defines the procedure call 31 ABI as follows. 32 33 Arguments are passed as if a structure containing the types of 34 the arguments were constructed. The first 16 bytes are passed in r4 35 through r7, the remainder on the stack. The first 16 bytes of a function 36 taking variable arguments are passed in r4-r7 in the same way. 37 38 Return values of types up to 8 bytes are returned in r2 and r3. For 39 return values greater than 8 bytes, the caller must allocate memory for 40 the result and pass the address as if it were argument 0. 41 42 While this isn't specified explicitly in the ABI documentation, GCC 43 promotes integral arguments smaller than int size to 32 bits. 44 45 Also of note, the ABI specifies that all structure objects are 46 aligned to 32 bits even if all their fields have a smaller natural 47 alignment. See FFI_AGGREGATE_ALIGNMENT. */ 48 49 50 /* Declare the assembly language hooks. */ 51 52 extern UINT64 ffi_call_sysv (void (*) (char *, extended_cif *), 53 extended_cif *, 54 unsigned, 55 void (*fn) (void)); 56 extern void ffi_closure_sysv (void); 57 58 /* Perform machine-dependent cif processing. */ 59 60 ffi_status ffi_prep_cif_machdep (ffi_cif *cif) 61 { 62 /* We always want at least 16 bytes in the parameter block since it 63 simplifies the low-level call function. Also round the parameter 64 block size up to a multiple of 4 bytes to preserve 65 32-bit alignment of the stack pointer. */ 66 if (cif->bytes < 16) 67 cif->bytes = 16; 68 else 69 cif->bytes = (cif->bytes + 3) & ~3; 70 71 return FFI_OK; 72 } 73 74 75 /* ffi_prep_args is called by the assembly routine to transfer arguments 76 to the stack using the pointers in the ecif array. 77 Note that the stack buffer is big enough to fit all the arguments, 78 but the first 16 bytes will be copied to registers for the actual 79 call. */ 80 81 void ffi_prep_args (char *stack, extended_cif *ecif) 82 { 83 char *argp = stack; 84 unsigned int i; 85 86 /* The implicit return value pointer is passed as if it were a hidden 87 first argument. */ 88 if (ecif->cif->rtype->type == FFI_TYPE_STRUCT 89 && ecif->cif->rtype->size > 8) 90 { 91 (*(void **) argp) = ecif->rvalue; 92 argp += 4; 93 } 94 95 for (i = 0; i < ecif->cif->nargs; i++) 96 { 97 void *avalue = ecif->avalue[i]; 98 ffi_type *atype = ecif->cif->arg_types[i]; 99 size_t size = atype->size; 100 size_t alignment = atype->alignment; 101 102 /* Align argp as appropriate for the argument type. */ 103 if ((alignment - 1) & (unsigned) argp) 104 argp = (char *) ALIGN (argp, alignment); 105 106 /* Copy the argument, promoting integral types smaller than a 107 word to word size. */ 108 if (size < sizeof (int)) 109 { 110 size = sizeof (int); 111 switch (atype->type) 112 { 113 case FFI_TYPE_SINT8: 114 *(signed int *) argp = (signed int) *(SINT8 *) avalue; 115 break; 116 117 case FFI_TYPE_UINT8: 118 *(unsigned int *) argp = (unsigned int) *(UINT8 *) avalue; 119 break; 120 121 case FFI_TYPE_SINT16: 122 *(signed int *) argp = (signed int) *(SINT16 *) avalue; 123 break; 124 125 case FFI_TYPE_UINT16: 126 *(unsigned int *) argp = (unsigned int) *(UINT16 *) avalue; 127 break; 128 129 case FFI_TYPE_STRUCT: 130 memcpy (argp, avalue, atype->size); 131 break; 132 133 default: 134 FFI_ASSERT(0); 135 } 136 } 137 else if (size == sizeof (int)) 138 *(unsigned int *) argp = (unsigned int) *(UINT32 *) avalue; 139 else 140 memcpy (argp, avalue, size); 141 argp += size; 142 } 143 } 144 145 146 /* Call FN using the prepared CIF. RVALUE points to space allocated by 147 the caller for the return value, and AVALUE is an array of argument 148 pointers. */ 149 150 void ffi_call (ffi_cif *cif, void (*fn) (void), void *rvalue, void **avalue) 151 { 152 153 extended_cif ecif; 154 UINT64 result; 155 156 /* If bigret is true, this is the case where a return value of larger 157 than 8 bytes is handled by being passed by reference as an implicit 158 argument. */ 159 int bigret = (cif->rtype->type == FFI_TYPE_STRUCT 160 && cif->rtype->size > 8); 161 162 ecif.cif = cif; 163 ecif.avalue = avalue; 164 165 /* Allocate space for return value if this is the pass-by-reference case 166 and the caller did not provide a buffer. */ 167 if (rvalue == NULL && bigret) 168 ecif.rvalue = alloca (cif->rtype->size); 169 else 170 ecif.rvalue = rvalue; 171 172 result = ffi_call_sysv (ffi_prep_args, &ecif, cif->bytes, fn); 173 174 /* Now result contains the 64 bit contents returned from fn in 175 r2 and r3. Copy the value of the appropriate size to the user-provided 176 rvalue buffer. */ 177 if (rvalue && !bigret) 178 switch (cif->rtype->size) 179 { 180 case 1: 181 *(UINT8 *)rvalue = (UINT8) result; 182 break; 183 case 2: 184 *(UINT16 *)rvalue = (UINT16) result; 185 break; 186 case 4: 187 *(UINT32 *)rvalue = (UINT32) result; 188 break; 189 case 8: 190 *(UINT64 *)rvalue = (UINT64) result; 191 break; 192 default: 193 memcpy (rvalue, (void *)&result, cif->rtype->size); 194 break; 195 } 196 } 197 198 /* This function is invoked from the closure trampoline to invoke 199 CLOSURE with argument block ARGS. Parse ARGS according to 200 CLOSURE->cfi and invoke CLOSURE->fun. */ 201 202 static UINT64 203 ffi_closure_helper (unsigned char *args, 204 ffi_closure *closure) 205 { 206 ffi_cif *cif = closure->cif; 207 unsigned char *argp = args; 208 void **parsed_args = alloca (cif->nargs * sizeof (void *)); 209 UINT64 result; 210 void *retptr; 211 unsigned int i; 212 213 /* First figure out what to do about the return type. If this is the 214 big-structure-return case, the first arg is the hidden return buffer 215 allocated by the caller. */ 216 if (cif->rtype->type == FFI_TYPE_STRUCT 217 && cif->rtype->size > 8) 218 { 219 retptr = *((void **) argp); 220 argp += 4; 221 } 222 else 223 retptr = (void *) &result; 224 225 /* Fill in the array of argument pointers. */ 226 for (i = 0; i < cif->nargs; i++) 227 { 228 size_t size = cif->arg_types[i]->size; 229 size_t alignment = cif->arg_types[i]->alignment; 230 231 /* Align argp as appropriate for the argument type. */ 232 if ((alignment - 1) & (unsigned) argp) 233 argp = (char *) ALIGN (argp, alignment); 234 235 /* Arguments smaller than an int are promoted to int. */ 236 if (size < sizeof (int)) 237 size = sizeof (int); 238 239 /* Store the pointer. */ 240 parsed_args[i] = argp; 241 argp += size; 242 } 243 244 /* Call the user-supplied function. */ 245 (closure->fun) (cif, retptr, parsed_args, closure->user_data); 246 return result; 247 } 248 249 250 /* Initialize CLOSURE with a trampoline to call FUN with 251 CIF and USER_DATA. */ 252 ffi_status 253 ffi_prep_closure_loc (ffi_closure* closure, 254 ffi_cif* cif, 255 void (*fun) (ffi_cif*, void*, void**, void*), 256 void *user_data, 257 void *codeloc) 258 { 259 unsigned int *tramp = (unsigned int *) &closure->tramp[0]; 260 int i; 261 262 if (cif->abi != FFI_SYSV) 263 return FFI_BAD_ABI; 264 265 /* The trampoline looks like: 266 movhi r8, %hi(ffi_closure_sysv) 267 ori r8, r8, %lo(ffi_closure_sysv) 268 movhi r9, %hi(ffi_closure_helper) 269 ori r0, r9, %lo(ffi_closure_helper) 270 movhi r10, %hi(closure) 271 ori r10, r10, %lo(closure) 272 jmp r8 273 and then ffi_closure_sysv retrieves the closure pointer out of r10 274 in addition to the arguments passed in the normal way for the call, 275 and invokes ffi_closure_helper. We encode the pointer to 276 ffi_closure_helper in the trampoline because making a PIC call 277 to it in ffi_closure_sysv would be messy (it would have to indirect 278 through the GOT). */ 279 280 #define HI(x) ((((unsigned int) (x)) >> 16) & 0xffff) 281 #define LO(x) (((unsigned int) (x)) & 0xffff) 282 tramp[0] = (0 << 27) | (8 << 22) | (HI (ffi_closure_sysv) << 6) | 0x34; 283 tramp[1] = (8 << 27) | (8 << 22) | (LO (ffi_closure_sysv) << 6) | 0x14; 284 tramp[2] = (0 << 27) | (9 << 22) | (HI (ffi_closure_helper) << 6) | 0x34; 285 tramp[3] = (9 << 27) | (9 << 22) | (LO (ffi_closure_helper) << 6) | 0x14; 286 tramp[4] = (0 << 27) | (10 << 22) | (HI (closure) << 6) | 0x34; 287 tramp[5] = (10 << 27) | (10 << 22) | (LO (closure) << 6) | 0x14; 288 tramp[6] = (8 << 27) | (0x0d << 11) | 0x3a; 289 #undef HI 290 #undef LO 291 292 /* Flush the caches. 293 See Example 9-4 in the Nios II Software Developer's Handbook. */ 294 for (i = 0; i < 7; i++) 295 asm volatile ("flushd 0(%0); flushi %0" :: "r"(tramp + i) : "memory"); 296 asm volatile ("flushp" ::: "memory"); 297 298 closure->cif = cif; 299 closure->fun = fun; 300 closure->user_data = user_data; 301 302 return FFI_OK; 303 } 304 305
