Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Linux/PA-RISC Project (http://www.parisc-linux.org/) |
| 3 | * |
| 4 | * System call entry code Copyright (c) Matthew Wilcox 1999 <willy@bofh.ai> |
| 5 | * Licensed under the GNU GPL. |
| 6 | * thanks to Philipp Rumpf, Mike Shaver and various others |
| 7 | * sorry about the wall, puffin.. |
| 8 | */ |
| 9 | |
Sam Ravnborg | 0013a85 | 2005-09-09 20:57:26 +0200 | [diff] [blame^] | 10 | #include <asm/asm-offsets.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | #include <asm/unistd.h> |
| 12 | #include <asm/errno.h> |
| 13 | #include <asm/psw.h> |
| 14 | #include <asm/thread_info.h> |
| 15 | |
| 16 | #include <asm/assembly.h> |
| 17 | #include <asm/processor.h> |
| 18 | |
| 19 | /* We fill the empty parts of the gateway page with |
| 20 | * something that will kill the kernel or a |
| 21 | * userspace application. |
| 22 | */ |
| 23 | #define KILL_INSN break 0,0 |
| 24 | |
| 25 | #include <linux/config.h> /* for CONFIG_SMP */ |
| 26 | |
| 27 | #ifdef __LP64__ |
| 28 | .level 2.0w |
| 29 | #else |
| 30 | .level 1.1 |
| 31 | #endif |
| 32 | |
| 33 | #ifndef __LP64__ |
| 34 | .macro fixup_branch,lbl |
| 35 | b \lbl |
| 36 | .endm |
| 37 | #else |
| 38 | .macro fixup_branch,lbl |
| 39 | ldil L%\lbl, %r1 |
| 40 | ldo R%\lbl(%r1), %r1 |
| 41 | bv,n %r0(%r1) |
| 42 | .endm |
| 43 | #endif |
| 44 | |
| 45 | .text |
| 46 | |
| 47 | .import syscall_exit,code |
| 48 | .import syscall_exit_rfi,code |
| 49 | .export linux_gateway_page |
| 50 | |
| 51 | /* Linux gateway page is aliased to virtual page 0 in the kernel |
| 52 | * address space. Since it is a gateway page it cannot be |
| 53 | * dereferenced, so null pointers will still fault. We start |
| 54 | * the actual entry point at 0x100. We put break instructions |
| 55 | * at the beginning of the page to trap null indirect function |
| 56 | * pointers. |
| 57 | */ |
| 58 | |
| 59 | .align 4096 |
| 60 | linux_gateway_page: |
| 61 | |
| 62 | /* ADDRESS 0x00 to 0xb0 = 176 bytes / 4 bytes per insn = 44 insns */ |
| 63 | .rept 44 |
| 64 | KILL_INSN |
| 65 | .endr |
| 66 | |
| 67 | /* ADDRESS 0xb0 to 0xb4, lws uses 1 insns for entry */ |
| 68 | /* Light-weight-syscall entry must always be located at 0xb0 */ |
| 69 | /* WARNING: Keep this number updated with table size changes */ |
| 70 | #define __NR_lws_entries (2) |
| 71 | |
| 72 | lws_entry: |
| 73 | /* Unconditional branch to lws_start, located on the |
| 74 | same gateway page */ |
| 75 | b,n lws_start |
| 76 | |
| 77 | /* Fill from 0xb4 to 0xe0 */ |
| 78 | .rept 11 |
| 79 | KILL_INSN |
| 80 | .endr |
| 81 | |
| 82 | /* This function MUST be located at 0xe0 for glibc's threading |
| 83 | mechanism to work. DO NOT MOVE THIS CODE EVER! */ |
| 84 | set_thread_pointer: |
| 85 | gate .+8, %r0 /* increase privilege */ |
| 86 | depi 3, 31, 2, %r31 /* Ensure we return into user mode. */ |
| 87 | be 0(%sr7,%r31) /* return to user space */ |
| 88 | mtctl %r26, %cr27 /* move arg0 to the control register */ |
| 89 | |
| 90 | /* Increase the chance of trapping if random jumps occur to this |
| 91 | address, fill from 0xf0 to 0x100 */ |
| 92 | .rept 4 |
| 93 | KILL_INSN |
| 94 | .endr |
| 95 | |
| 96 | /* This address must remain fixed at 0x100 for glibc's syscalls to work */ |
| 97 | .align 256 |
| 98 | linux_gateway_entry: |
| 99 | gate .+8, %r0 /* become privileged */ |
| 100 | mtsp %r0,%sr4 /* get kernel space into sr4 */ |
| 101 | mtsp %r0,%sr5 /* get kernel space into sr5 */ |
| 102 | mtsp %r0,%sr6 /* get kernel space into sr6 */ |
| 103 | mfsp %sr7,%r1 /* save user sr7 */ |
| 104 | mtsp %r1,%sr3 /* and store it in sr3 */ |
| 105 | |
| 106 | #ifdef __LP64__ |
| 107 | /* for now we can *always* set the W bit on entry to the syscall |
| 108 | * since we don't support wide userland processes. We could |
| 109 | * also save the current SM other than in r0 and restore it on |
| 110 | * exit from the syscall, and also use that value to know |
| 111 | * whether to do narrow or wide syscalls. -PB |
| 112 | */ |
| 113 | ssm PSW_SM_W, %r1 |
| 114 | extrd,u %r1,PSW_W_BIT,1,%r1 |
| 115 | /* sp must be aligned on 4, so deposit the W bit setting into |
| 116 | * the bottom of sp temporarily */ |
| 117 | or,ev %r1,%r30,%r30 |
| 118 | b,n 1f |
| 119 | /* The top halves of argument registers must be cleared on syscall |
| 120 | * entry from narrow executable. |
| 121 | */ |
| 122 | depdi 0, 31, 32, %r26 |
| 123 | depdi 0, 31, 32, %r25 |
| 124 | depdi 0, 31, 32, %r24 |
| 125 | depdi 0, 31, 32, %r23 |
| 126 | depdi 0, 31, 32, %r22 |
| 127 | depdi 0, 31, 32, %r21 |
| 128 | 1: |
| 129 | #endif |
| 130 | mfctl %cr30,%r1 |
| 131 | xor %r1,%r30,%r30 /* ye olde xor trick */ |
| 132 | xor %r1,%r30,%r1 |
| 133 | xor %r1,%r30,%r30 |
| 134 | |
| 135 | ldo THREAD_SZ_ALGN+FRAME_SIZE(%r30),%r30 /* set up kernel stack */ |
| 136 | |
| 137 | /* N.B.: It is critical that we don't set sr7 to 0 until r30 |
| 138 | * contains a valid kernel stack pointer. It is also |
| 139 | * critical that we don't start using the kernel stack |
| 140 | * until after sr7 has been set to 0. |
| 141 | */ |
| 142 | |
| 143 | mtsp %r0,%sr7 /* get kernel space into sr7 */ |
| 144 | STREGM %r1,FRAME_SIZE(%r30) /* save r1 (usp) here for now */ |
| 145 | mfctl %cr30,%r1 /* get task ptr in %r1 */ |
| 146 | LDREG TI_TASK(%r1),%r1 |
| 147 | |
| 148 | /* Save some registers for sigcontext and potential task |
| 149 | switch (see entry.S for the details of which ones are |
| 150 | saved/restored). TASK_PT_PSW is zeroed so we can see whether |
| 151 | a process is on a syscall or not. For an interrupt the real |
| 152 | PSW value is stored. This is needed for gdb and sys_ptrace. */ |
| 153 | STREG %r0, TASK_PT_PSW(%r1) |
| 154 | STREG %r2, TASK_PT_GR2(%r1) /* preserve rp */ |
| 155 | STREG %r19, TASK_PT_GR19(%r1) |
| 156 | |
| 157 | LDREGM -FRAME_SIZE(%r30), %r2 /* get users sp back */ |
| 158 | #ifdef __LP64__ |
| 159 | extrd,u %r2,63,1,%r19 /* W hidden in bottom bit */ |
| 160 | #if 0 |
| 161 | xor %r19,%r2,%r2 /* clear bottom bit */ |
| 162 | depd,z %r19,1,1,%r19 |
| 163 | std %r19,TASK_PT_PSW(%r1) |
| 164 | #endif |
| 165 | #endif |
| 166 | STREG %r2, TASK_PT_GR30(%r1) /* ... and save it */ |
| 167 | |
| 168 | STREG %r20, TASK_PT_GR20(%r1) |
| 169 | STREG %r21, TASK_PT_GR21(%r1) |
| 170 | STREG %r22, TASK_PT_GR22(%r1) |
| 171 | STREG %r23, TASK_PT_GR23(%r1) /* 4th argument */ |
| 172 | STREG %r24, TASK_PT_GR24(%r1) /* 3rd argument */ |
| 173 | STREG %r25, TASK_PT_GR25(%r1) /* 2nd argument */ |
| 174 | STREG %r26, TASK_PT_GR26(%r1) /* 1st argument */ |
| 175 | STREG %r27, TASK_PT_GR27(%r1) /* user dp */ |
| 176 | STREG %r28, TASK_PT_GR28(%r1) /* return value 0 */ |
| 177 | STREG %r28, TASK_PT_ORIG_R28(%r1) /* return value 0 (saved for signals) */ |
| 178 | STREG %r29, TASK_PT_GR29(%r1) /* return value 1 */ |
| 179 | STREG %r31, TASK_PT_GR31(%r1) /* preserve syscall return ptr */ |
| 180 | |
| 181 | ldo TASK_PT_FR0(%r1), %r27 /* save fpregs from the kernel */ |
| 182 | save_fp %r27 /* or potential task switch */ |
| 183 | |
| 184 | mfctl %cr11, %r27 /* i.e. SAR */ |
| 185 | STREG %r27, TASK_PT_SAR(%r1) |
| 186 | |
| 187 | loadgp |
| 188 | |
| 189 | #ifdef __LP64__ |
| 190 | ldo -16(%r30),%r29 /* Reference param save area */ |
| 191 | copy %r19,%r2 /* W bit back to r2 */ |
| 192 | #else |
| 193 | /* no need to save these on stack in wide mode because the first 8 |
| 194 | * args are passed in registers */ |
| 195 | stw %r22, -52(%r30) /* 5th argument */ |
| 196 | stw %r21, -56(%r30) /* 6th argument */ |
| 197 | #endif |
| 198 | |
| 199 | /* Are we being ptraced? */ |
| 200 | mfctl %cr30, %r1 |
| 201 | LDREG TI_TASK(%r1),%r1 |
| 202 | LDREG TASK_PTRACE(%r1), %r1 |
| 203 | bb,<,n %r1,31,.Ltracesys |
| 204 | |
| 205 | /* Note! We cannot use the syscall table that is mapped |
| 206 | nearby since the gateway page is mapped execute-only. */ |
| 207 | |
| 208 | #ifdef __LP64__ |
| 209 | ldil L%sys_call_table, %r1 |
| 210 | or,= %r2,%r2,%r2 |
| 211 | addil L%(sys_call_table64-sys_call_table), %r1 |
| 212 | ldo R%sys_call_table(%r1), %r19 |
| 213 | or,= %r2,%r2,%r2 |
| 214 | ldo R%sys_call_table64(%r1), %r19 |
| 215 | #else |
| 216 | ldil L%sys_call_table, %r1 |
| 217 | ldo R%sys_call_table(%r1), %r19 |
| 218 | #endif |
| 219 | comiclr,>>= __NR_Linux_syscalls, %r20, %r0 |
| 220 | b,n .Lsyscall_nosys |
| 221 | |
| 222 | LDREGX %r20(%r19), %r19 |
| 223 | |
| 224 | /* If this is a sys_rt_sigreturn call, and the signal was received |
| 225 | * when not in_syscall, then we want to return via syscall_exit_rfi, |
| 226 | * not syscall_exit. Signal no. in r20, in_syscall in r25 (see |
| 227 | * trampoline code in signal.c). |
| 228 | */ |
| 229 | ldi __NR_rt_sigreturn,%r2 |
| 230 | comb,= %r2,%r20,.Lrt_sigreturn |
| 231 | .Lin_syscall: |
| 232 | ldil L%syscall_exit,%r2 |
| 233 | be 0(%sr7,%r19) |
| 234 | ldo R%syscall_exit(%r2),%r2 |
| 235 | .Lrt_sigreturn: |
| 236 | comib,<> 0,%r25,.Lin_syscall |
| 237 | ldil L%syscall_exit_rfi,%r2 |
| 238 | be 0(%sr7,%r19) |
| 239 | ldo R%syscall_exit_rfi(%r2),%r2 |
| 240 | |
| 241 | /* Note! Because we are not running where we were linked, any |
| 242 | calls to functions external to this file must be indirect. To |
| 243 | be safe, we apply the opposite rule to functions within this |
| 244 | file, with local labels given to them to ensure correctness. */ |
| 245 | |
| 246 | .Lsyscall_nosys: |
| 247 | syscall_nosys: |
| 248 | ldil L%syscall_exit,%r1 |
| 249 | be R%syscall_exit(%sr7,%r1) |
| 250 | ldo -ENOSYS(%r0),%r28 /* set errno */ |
| 251 | |
| 252 | |
| 253 | /* Warning! This trace code is a virtual duplicate of the code above so be |
| 254 | * sure to maintain both! */ |
| 255 | .Ltracesys: |
| 256 | tracesys: |
| 257 | /* Need to save more registers so the debugger can see where we |
| 258 | * are. This saves only the lower 8 bits of PSW, so that the C |
| 259 | * bit is still clear on syscalls, and the D bit is set if this |
| 260 | * full register save path has been executed. We check the D |
| 261 | * bit on syscall_return_rfi to determine which registers to |
| 262 | * restore. An interrupt results in a full PSW saved with the |
| 263 | * C bit set, a non-straced syscall entry results in C and D clear |
| 264 | * in the saved PSW. |
| 265 | */ |
| 266 | ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ |
| 267 | LDREG TI_TASK(%r1), %r1 |
| 268 | ssm 0,%r2 |
| 269 | STREG %r2,TASK_PT_PSW(%r1) /* Lower 8 bits only!! */ |
| 270 | mfsp %sr0,%r2 |
| 271 | STREG %r2,TASK_PT_SR0(%r1) |
| 272 | mfsp %sr1,%r2 |
| 273 | STREG %r2,TASK_PT_SR1(%r1) |
| 274 | mfsp %sr2,%r2 |
| 275 | STREG %r2,TASK_PT_SR2(%r1) |
| 276 | mfsp %sr3,%r2 |
| 277 | STREG %r2,TASK_PT_SR3(%r1) |
| 278 | STREG %r2,TASK_PT_SR4(%r1) |
| 279 | STREG %r2,TASK_PT_SR5(%r1) |
| 280 | STREG %r2,TASK_PT_SR6(%r1) |
| 281 | STREG %r2,TASK_PT_SR7(%r1) |
| 282 | STREG %r2,TASK_PT_IASQ0(%r1) |
| 283 | STREG %r2,TASK_PT_IASQ1(%r1) |
| 284 | LDREG TASK_PT_GR31(%r1),%r2 |
| 285 | STREG %r2,TASK_PT_IAOQ0(%r1) |
| 286 | ldo 4(%r2),%r2 |
| 287 | STREG %r2,TASK_PT_IAOQ1(%r1) |
| 288 | ldo TASK_REGS(%r1),%r2 |
| 289 | /* reg_save %r2 */ |
| 290 | STREG %r3,PT_GR3(%r2) |
| 291 | STREG %r4,PT_GR4(%r2) |
| 292 | STREG %r5,PT_GR5(%r2) |
| 293 | STREG %r6,PT_GR6(%r2) |
| 294 | STREG %r7,PT_GR7(%r2) |
| 295 | STREG %r8,PT_GR8(%r2) |
| 296 | STREG %r9,PT_GR9(%r2) |
| 297 | STREG %r10,PT_GR10(%r2) |
| 298 | STREG %r11,PT_GR11(%r2) |
| 299 | STREG %r12,PT_GR12(%r2) |
| 300 | STREG %r13,PT_GR13(%r2) |
| 301 | STREG %r14,PT_GR14(%r2) |
| 302 | STREG %r15,PT_GR15(%r2) |
| 303 | STREG %r16,PT_GR16(%r2) |
| 304 | STREG %r17,PT_GR17(%r2) |
| 305 | STREG %r18,PT_GR18(%r2) |
| 306 | /* Finished saving things for the debugger */ |
| 307 | |
| 308 | ldil L%syscall_trace,%r1 |
| 309 | ldil L%tracesys_next,%r2 |
| 310 | be R%syscall_trace(%sr7,%r1) |
| 311 | ldo R%tracesys_next(%r2),%r2 |
| 312 | |
| 313 | tracesys_next: |
| 314 | ldil L%sys_call_table,%r1 |
| 315 | ldo R%sys_call_table(%r1), %r19 |
| 316 | |
| 317 | ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ |
| 318 | LDREG TI_TASK(%r1), %r1 |
| 319 | LDREG TASK_PT_GR20(%r1), %r20 |
| 320 | LDREG TASK_PT_GR26(%r1), %r26 /* Restore the users args */ |
| 321 | LDREG TASK_PT_GR25(%r1), %r25 |
| 322 | LDREG TASK_PT_GR24(%r1), %r24 |
| 323 | LDREG TASK_PT_GR23(%r1), %r23 |
| 324 | #ifdef __LP64__ |
| 325 | LDREG TASK_PT_GR22(%r1), %r22 |
| 326 | LDREG TASK_PT_GR21(%r1), %r21 |
| 327 | ldo -16(%r30),%r29 /* Reference param save area */ |
| 328 | #endif |
| 329 | |
| 330 | comiclr,>>= __NR_Linux_syscalls, %r20, %r0 |
| 331 | b,n .Lsyscall_nosys |
| 332 | |
| 333 | LDREGX %r20(%r19), %r19 |
| 334 | |
| 335 | /* If this is a sys_rt_sigreturn call, and the signal was received |
| 336 | * when not in_syscall, then we want to return via syscall_exit_rfi, |
| 337 | * not syscall_exit. Signal no. in r20, in_syscall in r25 (see |
| 338 | * trampoline code in signal.c). |
| 339 | */ |
| 340 | ldi __NR_rt_sigreturn,%r2 |
| 341 | comb,= %r2,%r20,.Ltrace_rt_sigreturn |
| 342 | .Ltrace_in_syscall: |
| 343 | ldil L%tracesys_exit,%r2 |
| 344 | be 0(%sr7,%r19) |
| 345 | ldo R%tracesys_exit(%r2),%r2 |
| 346 | |
| 347 | /* Do *not* call this function on the gateway page, because it |
| 348 | makes a direct call to syscall_trace. */ |
| 349 | |
| 350 | tracesys_exit: |
| 351 | ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ |
| 352 | LDREG TI_TASK(%r1), %r1 |
| 353 | #ifdef __LP64__ |
| 354 | ldo -16(%r30),%r29 /* Reference param save area */ |
| 355 | #endif |
| 356 | bl syscall_trace, %r2 |
| 357 | STREG %r28,TASK_PT_GR28(%r1) /* save return value now */ |
| 358 | ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ |
| 359 | LDREG TI_TASK(%r1), %r1 |
| 360 | LDREG TASK_PT_GR28(%r1), %r28 /* Restore return val. */ |
| 361 | |
| 362 | ldil L%syscall_exit,%r1 |
| 363 | be,n R%syscall_exit(%sr7,%r1) |
| 364 | |
| 365 | .Ltrace_rt_sigreturn: |
| 366 | comib,<> 0,%r25,.Ltrace_in_syscall |
| 367 | ldil L%tracesys_sigexit,%r2 |
| 368 | be 0(%sr7,%r19) |
| 369 | ldo R%tracesys_sigexit(%r2),%r2 |
| 370 | |
| 371 | tracesys_sigexit: |
| 372 | ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ |
| 373 | LDREG 0(%r1), %r1 |
| 374 | #ifdef __LP64__ |
| 375 | ldo -16(%r30),%r29 /* Reference param save area */ |
| 376 | #endif |
| 377 | bl syscall_trace, %r2 |
| 378 | nop |
| 379 | |
| 380 | ldil L%syscall_exit_rfi,%r1 |
| 381 | be,n R%syscall_exit_rfi(%sr7,%r1) |
| 382 | |
| 383 | |
| 384 | /********************************************************* |
| 385 | Light-weight-syscall code |
| 386 | |
| 387 | r20 - lws number |
| 388 | r26,r25,r24,r23,r22 - Input registers |
| 389 | r28 - Function return register |
| 390 | r21 - Error code. |
| 391 | |
| 392 | Scracth: Any of the above that aren't being |
| 393 | currently used, including r1. |
| 394 | |
| 395 | Return pointer: r31 (Not usable) |
| 396 | |
| 397 | Error codes returned by entry path: |
| 398 | |
| 399 | ENOSYS - r20 was an invalid LWS number. |
| 400 | |
| 401 | *********************************************************/ |
| 402 | lws_start: |
| 403 | /* Gate and ensure we return to userspace */ |
| 404 | gate .+8, %r0 |
| 405 | depi 3, 31, 2, %r31 /* Ensure we return to userspace */ |
| 406 | |
| 407 | #ifdef __LP64__ |
| 408 | /* FIXME: If we are a 64-bit kernel just |
| 409 | * turn this on unconditionally. |
| 410 | */ |
| 411 | ssm PSW_SM_W, %r1 |
| 412 | extrd,u %r1,PSW_W_BIT,1,%r1 |
| 413 | /* sp must be aligned on 4, so deposit the W bit setting into |
| 414 | * the bottom of sp temporarily */ |
| 415 | or,ev %r1,%r30,%r30 |
| 416 | |
| 417 | /* Clip LWS number to a 32-bit value always */ |
| 418 | depdi 0, 31, 32, %r20 |
| 419 | #endif |
| 420 | |
| 421 | /* Is the lws entry number valid? */ |
| 422 | comiclr,>>= __NR_lws_entries, %r20, %r0 |
| 423 | b,n lws_exit_nosys |
| 424 | |
| 425 | /* WARNING: Trashing sr2 and sr3 */ |
| 426 | mfsp %sr7,%r1 /* get userspace into sr3 */ |
| 427 | mtsp %r1,%sr3 |
| 428 | mtsp %r0,%sr2 /* get kernel space into sr2 */ |
| 429 | |
| 430 | /* Load table start */ |
| 431 | ldil L%lws_table, %r1 |
| 432 | ldo R%lws_table(%r1), %r28 /* Scratch use of r28 */ |
| 433 | LDREGX %r20(%sr2,r28), %r21 /* Scratch use of r21 */ |
| 434 | |
| 435 | /* Jump to lws, lws table pointers already relocated */ |
| 436 | be,n 0(%sr2,%r21) |
| 437 | |
| 438 | lws_exit_nosys: |
| 439 | ldo -ENOSYS(%r0),%r21 /* set errno */ |
| 440 | /* Fall through: Return to userspace */ |
| 441 | |
| 442 | lws_exit: |
| 443 | #ifdef __LP64__ |
| 444 | /* decide whether to reset the wide mode bit |
| 445 | * |
| 446 | * For a syscall, the W bit is stored in the lowest bit |
| 447 | * of sp. Extract it and reset W if it is zero */ |
| 448 | extrd,u,*<> %r30,63,1,%r1 |
| 449 | rsm PSW_SM_W, %r0 |
| 450 | /* now reset the lowest bit of sp if it was set */ |
| 451 | xor %r30,%r1,%r30 |
| 452 | #endif |
| 453 | be,n 0(%sr3, %r31) |
| 454 | |
| 455 | |
| 456 | |
| 457 | /*************************************************** |
| 458 | Implementing CAS as an atomic operation: |
| 459 | |
| 460 | %r26 - Address to examine |
| 461 | %r25 - Old value to check (old) |
| 462 | %r24 - New value to set (new) |
| 463 | %r28 - Return prev through this register. |
| 464 | %r21 - Kernel error code |
| 465 | |
| 466 | If debugging is DISabled: |
| 467 | |
| 468 | %r21 has the following meanings: |
| 469 | |
| 470 | EAGAIN - CAS is busy, ldcw failed, try again. |
| 471 | EFAULT - Read or write failed. |
| 472 | |
| 473 | If debugging is enabled: |
| 474 | |
| 475 | EDEADLOCK - CAS called recursively. |
| 476 | EAGAIN && r28 == 1 - CAS is busy. Lock contended. |
| 477 | EAGAIN && r28 == 2 - CAS is busy. ldcw failed. |
| 478 | EFAULT - Read or write failed. |
| 479 | |
| 480 | Scratch: r20, r28, r1 |
| 481 | |
| 482 | ****************************************************/ |
| 483 | |
| 484 | /* Do not enable LWS debugging */ |
| 485 | #define ENABLE_LWS_DEBUG 0 |
| 486 | |
| 487 | /* ELF64 Process entry path */ |
| 488 | lws_compare_and_swap64: |
| 489 | #ifdef __LP64__ |
| 490 | b,n lws_compare_and_swap |
| 491 | #else |
| 492 | /* If we are not a 64-bit kernel, then we don't |
| 493 | * implement having 64-bit input registers |
| 494 | */ |
| 495 | b,n lws_exit_nosys |
| 496 | #endif |
| 497 | |
| 498 | /* ELF32 Process entry path */ |
| 499 | lws_compare_and_swap32: |
| 500 | #ifdef __LP64__ |
| 501 | /* Clip all the input registers */ |
| 502 | depdi 0, 31, 32, %r26 |
| 503 | depdi 0, 31, 32, %r25 |
| 504 | depdi 0, 31, 32, %r24 |
| 505 | #endif |
| 506 | |
| 507 | lws_compare_and_swap: |
| 508 | #ifdef CONFIG_SMP |
| 509 | /* Load start of lock table */ |
| 510 | ldil L%lws_lock_start, %r20 |
| 511 | ldo R%lws_lock_start(%r20), %r28 |
| 512 | |
| 513 | /* Extract four bits from r26 and hash lock (Bits 4-7) */ |
| 514 | extru %r26, 27, 4, %r20 |
| 515 | |
| 516 | /* Find lock to use, the hash is either one of 0 to |
| 517 | 15, multiplied by 16 (keep it 16-byte aligned) |
| 518 | and add to the lock table offset. */ |
| 519 | shlw %r20, 4, %r20 |
| 520 | add %r20, %r28, %r20 |
| 521 | |
| 522 | # ifdef ENABLE_LWS_DEBUG |
| 523 | /* |
| 524 | DEBUG, check for deadlock! |
| 525 | If the thread register values are the same |
| 526 | then we were the one that locked it last and |
| 527 | this is a recurisve call that will deadlock. |
| 528 | We *must* giveup this call and fail. |
| 529 | */ |
| 530 | ldw 4(%sr2,%r20), %r28 /* Load thread register */ |
| 531 | mfctl %cr27, %r21 /* Get current thread register */ |
| 532 | cmpb,<>,n %r21, %r28, cas_lock /* Called recursive? */ |
| 533 | b lws_exit /* Return error! */ |
| 534 | ldo -EDEADLOCK(%r0), %r21 |
| 535 | cas_lock: |
| 536 | cmpb,=,n %r0, %r28, cas_nocontend /* Is nobody using it? */ |
| 537 | ldo 1(%r0), %r28 /* 1st case */ |
| 538 | b lws_exit /* Contended... */ |
| 539 | ldo -EAGAIN(%r0), %r21 /* Spin in userspace */ |
| 540 | cas_nocontend: |
| 541 | # endif |
| 542 | /* ENABLE_LWS_DEBUG */ |
| 543 | |
| 544 | ldcw 0(%sr2,%r20), %r28 /* Try to acquire the lock */ |
| 545 | cmpb,<>,n %r0, %r28, cas_action /* Did we get it? */ |
| 546 | cas_wouldblock: |
| 547 | ldo 2(%r0), %r28 /* 2nd case */ |
| 548 | b lws_exit /* Contended... */ |
| 549 | ldo -EAGAIN(%r0), %r21 /* Spin in userspace */ |
| 550 | #endif |
| 551 | /* CONFIG_SMP */ |
| 552 | |
| 553 | /* |
| 554 | prev = *addr; |
| 555 | if ( prev == old ) |
| 556 | *addr = new; |
| 557 | return prev; |
| 558 | */ |
| 559 | |
| 560 | /* NOTES: |
| 561 | This all works becuse intr_do_signal |
| 562 | and schedule both check the return iasq |
| 563 | and see that we are on the kernel page |
| 564 | so this process is never scheduled off |
| 565 | or is ever sent any signal of any sort, |
| 566 | thus it is wholly atomic from usrspaces |
| 567 | perspective |
| 568 | */ |
| 569 | cas_action: |
| 570 | #if defined CONFIG_SMP && defined ENABLE_LWS_DEBUG |
| 571 | /* DEBUG */ |
| 572 | mfctl %cr27, %r1 |
| 573 | stw %r1, 4(%sr2,%r20) |
| 574 | #endif |
| 575 | /* The load and store could fail */ |
| 576 | 1: ldw 0(%sr3,%r26), %r28 |
| 577 | sub,<> %r28, %r25, %r0 |
| 578 | 2: stw %r24, 0(%sr3,%r26) |
| 579 | #ifdef CONFIG_SMP |
| 580 | /* Free lock */ |
| 581 | stw %r20, 0(%sr2,%r20) |
| 582 | # ifdef ENABLE_LWS_DEBUG |
| 583 | /* Clear thread register indicator */ |
| 584 | stw %r0, 4(%sr2,%r20) |
| 585 | # endif |
| 586 | #endif |
| 587 | /* Return to userspace, set no error */ |
| 588 | b lws_exit |
| 589 | copy %r0, %r21 |
| 590 | |
| 591 | 3: |
| 592 | /* Error occured on load or store */ |
| 593 | #ifdef CONFIG_SMP |
| 594 | /* Free lock */ |
| 595 | stw %r20, 0(%sr2,%r20) |
| 596 | # ifdef ENABLE_LWS_DEBUG |
| 597 | stw %r0, 4(%sr2,%r20) |
| 598 | # endif |
| 599 | #endif |
| 600 | b lws_exit |
| 601 | ldo -EFAULT(%r0),%r21 /* set errno */ |
| 602 | nop |
| 603 | nop |
| 604 | nop |
| 605 | nop |
| 606 | |
| 607 | /* Two exception table entries, one for the load, |
| 608 | the other for the store. Either return -EFAULT. |
| 609 | Each of the entries must be relocated. */ |
| 610 | .section __ex_table,"aw" |
| 611 | #ifdef __LP64__ |
| 612 | /* Pad the address calculation */ |
| 613 | .word 0,(2b - linux_gateway_page) |
| 614 | .word 0,(3b - linux_gateway_page) |
| 615 | #else |
| 616 | .word (2b - linux_gateway_page) |
| 617 | .word (3b - linux_gateway_page) |
| 618 | #endif |
| 619 | .previous |
| 620 | |
| 621 | .section __ex_table,"aw" |
| 622 | #ifdef __LP64__ |
| 623 | /* Pad the address calculation */ |
| 624 | .word 0,(1b - linux_gateway_page) |
| 625 | .word 0,(3b - linux_gateway_page) |
| 626 | #else |
| 627 | .word (1b - linux_gateway_page) |
| 628 | .word (3b - linux_gateway_page) |
| 629 | #endif |
| 630 | .previous |
| 631 | |
| 632 | end_compare_and_swap: |
| 633 | |
| 634 | /* Make sure nothing else is placed on this page */ |
| 635 | .align 4096 |
| 636 | .export end_linux_gateway_page |
| 637 | end_linux_gateway_page: |
| 638 | |
| 639 | /* Relocate symbols assuming linux_gateway_page is mapped |
| 640 | to virtual address 0x0 */ |
| 641 | #ifdef __LP64__ |
| 642 | /* FIXME: The code will always be on the gateay page |
| 643 | and thus it will be on the first 4k, the |
| 644 | assembler seems to think that the final |
| 645 | subtraction result is only a word in |
| 646 | length, so we pad the value. |
| 647 | */ |
| 648 | #define LWS_ENTRY(_name_) .word 0,(lws_##_name_ - linux_gateway_page) |
| 649 | #else |
| 650 | #define LWS_ENTRY(_name_) .word (lws_##_name_ - linux_gateway_page) |
| 651 | #endif |
| 652 | |
| 653 | .align 4096 |
| 654 | /* Light-weight-syscall table */ |
| 655 | /* Start of lws table. */ |
| 656 | .export lws_table |
| 657 | .Llws_table: |
| 658 | lws_table: |
| 659 | LWS_ENTRY(compare_and_swap32) /* 0 - ELF32 Atomic compare and swap */ |
| 660 | LWS_ENTRY(compare_and_swap64) /* 1 - ELF64 Atomic compare and swap */ |
| 661 | /* End of lws table */ |
| 662 | |
| 663 | .align 4096 |
| 664 | .export sys_call_table |
| 665 | .Lsys_call_table: |
| 666 | sys_call_table: |
| 667 | #include "syscall_table.S" |
| 668 | |
| 669 | #ifdef __LP64__ |
| 670 | .align 4096 |
| 671 | .export sys_call_table64 |
| 672 | .Lsys_call_table64: |
| 673 | sys_call_table64: |
| 674 | #define SYSCALL_TABLE_64BIT |
| 675 | #include "syscall_table.S" |
| 676 | #endif |
| 677 | |
| 678 | #ifdef CONFIG_SMP |
| 679 | /* |
| 680 | All light-weight-syscall atomic operations |
| 681 | will use this set of locks |
| 682 | */ |
| 683 | .section .data |
| 684 | .align 4096 |
| 685 | .export lws_lock_start |
| 686 | .Llws_lock_start: |
| 687 | lws_lock_start: |
| 688 | /* lws locks */ |
| 689 | .align 16 |
| 690 | .rept 16 |
| 691 | /* Keep locks aligned at 16-bytes */ |
| 692 | .word 1 |
| 693 | .word 0 |
| 694 | .word 0 |
| 695 | .word 0 |
| 696 | .endr |
| 697 | .previous |
| 698 | #endif |
| 699 | /* CONFIG_SMP for lws_lock_start */ |
| 700 | |
| 701 | .end |
| 702 | |
| 703 | |