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1da177e4 LT |
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 | */ | |
413059f2 | 9 | #include <linux/config.h> /* for CONFIG_SMP */ |
1da177e4 | 10 | |
0013a854 | 11 | #include <asm/asm-offsets.h> |
1da177e4 LT |
12 | #include <asm/unistd.h> |
13 | #include <asm/errno.h> | |
14 | #include <asm/psw.h> | |
15 | #include <asm/thread_info.h> | |
16 | ||
17 | #include <asm/assembly.h> | |
18 | #include <asm/processor.h> | |
19 | ||
20 | /* We fill the empty parts of the gateway page with | |
21 | * something that will kill the kernel or a | |
22 | * userspace application. | |
23 | */ | |
24 | #define KILL_INSN break 0,0 | |
25 | ||
413059f2 | 26 | #ifdef CONFIG_64BIT |
1da177e4 LT |
27 | .level 2.0w |
28 | #else | |
29 | .level 1.1 | |
30 | #endif | |
31 | ||
413059f2 | 32 | #ifndef CONFIG_64BIT |
1da177e4 LT |
33 | .macro fixup_branch,lbl |
34 | b \lbl | |
35 | .endm | |
36 | #else | |
37 | .macro fixup_branch,lbl | |
38 | ldil L%\lbl, %r1 | |
39 | ldo R%\lbl(%r1), %r1 | |
40 | bv,n %r0(%r1) | |
41 | .endm | |
42 | #endif | |
43 | ||
44 | .text | |
45 | ||
46 | .import syscall_exit,code | |
47 | .import syscall_exit_rfi,code | |
48 | .export linux_gateway_page | |
49 | ||
50 | /* Linux gateway page is aliased to virtual page 0 in the kernel | |
51 | * address space. Since it is a gateway page it cannot be | |
52 | * dereferenced, so null pointers will still fault. We start | |
53 | * the actual entry point at 0x100. We put break instructions | |
54 | * at the beginning of the page to trap null indirect function | |
55 | * pointers. | |
56 | */ | |
57 | ||
58 | .align 4096 | |
59 | linux_gateway_page: | |
60 | ||
61 | /* ADDRESS 0x00 to 0xb0 = 176 bytes / 4 bytes per insn = 44 insns */ | |
62 | .rept 44 | |
63 | KILL_INSN | |
64 | .endr | |
65 | ||
66 | /* ADDRESS 0xb0 to 0xb4, lws uses 1 insns for entry */ | |
67 | /* Light-weight-syscall entry must always be located at 0xb0 */ | |
68 | /* WARNING: Keep this number updated with table size changes */ | |
69 | #define __NR_lws_entries (2) | |
70 | ||
71 | lws_entry: | |
72 | /* Unconditional branch to lws_start, located on the | |
73 | same gateway page */ | |
74 | b,n lws_start | |
75 | ||
76 | /* Fill from 0xb4 to 0xe0 */ | |
77 | .rept 11 | |
78 | KILL_INSN | |
79 | .endr | |
80 | ||
81 | /* This function MUST be located at 0xe0 for glibc's threading | |
82 | mechanism to work. DO NOT MOVE THIS CODE EVER! */ | |
83 | set_thread_pointer: | |
84 | gate .+8, %r0 /* increase privilege */ | |
85 | depi 3, 31, 2, %r31 /* Ensure we return into user mode. */ | |
86 | be 0(%sr7,%r31) /* return to user space */ | |
87 | mtctl %r26, %cr27 /* move arg0 to the control register */ | |
88 | ||
89 | /* Increase the chance of trapping if random jumps occur to this | |
90 | address, fill from 0xf0 to 0x100 */ | |
91 | .rept 4 | |
92 | KILL_INSN | |
93 | .endr | |
94 | ||
95 | /* This address must remain fixed at 0x100 for glibc's syscalls to work */ | |
96 | .align 256 | |
97 | linux_gateway_entry: | |
98 | gate .+8, %r0 /* become privileged */ | |
99 | mtsp %r0,%sr4 /* get kernel space into sr4 */ | |
100 | mtsp %r0,%sr5 /* get kernel space into sr5 */ | |
101 | mtsp %r0,%sr6 /* get kernel space into sr6 */ | |
102 | mfsp %sr7,%r1 /* save user sr7 */ | |
103 | mtsp %r1,%sr3 /* and store it in sr3 */ | |
104 | ||
413059f2 | 105 | #ifdef CONFIG_64BIT |
1da177e4 LT |
106 | /* for now we can *always* set the W bit on entry to the syscall |
107 | * since we don't support wide userland processes. We could | |
108 | * also save the current SM other than in r0 and restore it on | |
109 | * exit from the syscall, and also use that value to know | |
110 | * whether to do narrow or wide syscalls. -PB | |
111 | */ | |
112 | ssm PSW_SM_W, %r1 | |
113 | extrd,u %r1,PSW_W_BIT,1,%r1 | |
114 | /* sp must be aligned on 4, so deposit the W bit setting into | |
115 | * the bottom of sp temporarily */ | |
116 | or,ev %r1,%r30,%r30 | |
117 | b,n 1f | |
118 | /* The top halves of argument registers must be cleared on syscall | |
119 | * entry from narrow executable. | |
120 | */ | |
121 | depdi 0, 31, 32, %r26 | |
122 | depdi 0, 31, 32, %r25 | |
123 | depdi 0, 31, 32, %r24 | |
124 | depdi 0, 31, 32, %r23 | |
125 | depdi 0, 31, 32, %r22 | |
126 | depdi 0, 31, 32, %r21 | |
127 | 1: | |
128 | #endif | |
129 | mfctl %cr30,%r1 | |
130 | xor %r1,%r30,%r30 /* ye olde xor trick */ | |
131 | xor %r1,%r30,%r1 | |
132 | xor %r1,%r30,%r30 | |
133 | ||
134 | ldo THREAD_SZ_ALGN+FRAME_SIZE(%r30),%r30 /* set up kernel stack */ | |
135 | ||
136 | /* N.B.: It is critical that we don't set sr7 to 0 until r30 | |
137 | * contains a valid kernel stack pointer. It is also | |
138 | * critical that we don't start using the kernel stack | |
139 | * until after sr7 has been set to 0. | |
140 | */ | |
141 | ||
142 | mtsp %r0,%sr7 /* get kernel space into sr7 */ | |
143 | STREGM %r1,FRAME_SIZE(%r30) /* save r1 (usp) here for now */ | |
144 | mfctl %cr30,%r1 /* get task ptr in %r1 */ | |
145 | LDREG TI_TASK(%r1),%r1 | |
146 | ||
147 | /* Save some registers for sigcontext and potential task | |
148 | switch (see entry.S for the details of which ones are | |
149 | saved/restored). TASK_PT_PSW is zeroed so we can see whether | |
150 | a process is on a syscall or not. For an interrupt the real | |
151 | PSW value is stored. This is needed for gdb and sys_ptrace. */ | |
152 | STREG %r0, TASK_PT_PSW(%r1) | |
153 | STREG %r2, TASK_PT_GR2(%r1) /* preserve rp */ | |
154 | STREG %r19, TASK_PT_GR19(%r1) | |
155 | ||
156 | LDREGM -FRAME_SIZE(%r30), %r2 /* get users sp back */ | |
413059f2 | 157 | #ifdef CONFIG_64BIT |
1da177e4 LT |
158 | extrd,u %r2,63,1,%r19 /* W hidden in bottom bit */ |
159 | #if 0 | |
160 | xor %r19,%r2,%r2 /* clear bottom bit */ | |
161 | depd,z %r19,1,1,%r19 | |
162 | std %r19,TASK_PT_PSW(%r1) | |
163 | #endif | |
164 | #endif | |
165 | STREG %r2, TASK_PT_GR30(%r1) /* ... and save it */ | |
166 | ||
aa0eecb0 | 167 | STREG %r20, TASK_PT_GR20(%r1) /* Syscall number */ |
1da177e4 LT |
168 | STREG %r21, TASK_PT_GR21(%r1) |
169 | STREG %r22, TASK_PT_GR22(%r1) | |
170 | STREG %r23, TASK_PT_GR23(%r1) /* 4th argument */ | |
171 | STREG %r24, TASK_PT_GR24(%r1) /* 3rd argument */ | |
172 | STREG %r25, TASK_PT_GR25(%r1) /* 2nd argument */ | |
173 | STREG %r26, TASK_PT_GR26(%r1) /* 1st argument */ | |
174 | STREG %r27, TASK_PT_GR27(%r1) /* user dp */ | |
175 | STREG %r28, TASK_PT_GR28(%r1) /* return value 0 */ | |
176 | STREG %r28, TASK_PT_ORIG_R28(%r1) /* return value 0 (saved for signals) */ | |
177 | STREG %r29, TASK_PT_GR29(%r1) /* return value 1 */ | |
178 | STREG %r31, TASK_PT_GR31(%r1) /* preserve syscall return ptr */ | |
179 | ||
180 | ldo TASK_PT_FR0(%r1), %r27 /* save fpregs from the kernel */ | |
181 | save_fp %r27 /* or potential task switch */ | |
182 | ||
183 | mfctl %cr11, %r27 /* i.e. SAR */ | |
184 | STREG %r27, TASK_PT_SAR(%r1) | |
185 | ||
186 | loadgp | |
187 | ||
413059f2 | 188 | #ifdef CONFIG_64BIT |
1da177e4 LT |
189 | ldo -16(%r30),%r29 /* Reference param save area */ |
190 | copy %r19,%r2 /* W bit back to r2 */ | |
191 | #else | |
192 | /* no need to save these on stack in wide mode because the first 8 | |
193 | * args are passed in registers */ | |
194 | stw %r22, -52(%r30) /* 5th argument */ | |
195 | stw %r21, -56(%r30) /* 6th argument */ | |
196 | #endif | |
197 | ||
198 | /* Are we being ptraced? */ | |
199 | mfctl %cr30, %r1 | |
200 | LDREG TI_TASK(%r1),%r1 | |
201 | LDREG TASK_PTRACE(%r1), %r1 | |
202 | bb,<,n %r1,31,.Ltracesys | |
203 | ||
204 | /* Note! We cannot use the syscall table that is mapped | |
205 | nearby since the gateway page is mapped execute-only. */ | |
206 | ||
413059f2 | 207 | #ifdef CONFIG_64BIT |
1da177e4 LT |
208 | ldil L%sys_call_table, %r1 |
209 | or,= %r2,%r2,%r2 | |
210 | addil L%(sys_call_table64-sys_call_table), %r1 | |
211 | ldo R%sys_call_table(%r1), %r19 | |
212 | or,= %r2,%r2,%r2 | |
213 | ldo R%sys_call_table64(%r1), %r19 | |
214 | #else | |
215 | ldil L%sys_call_table, %r1 | |
216 | ldo R%sys_call_table(%r1), %r19 | |
217 | #endif | |
218 | comiclr,>>= __NR_Linux_syscalls, %r20, %r0 | |
219 | b,n .Lsyscall_nosys | |
220 | ||
221 | LDREGX %r20(%r19), %r19 | |
222 | ||
223 | /* If this is a sys_rt_sigreturn call, and the signal was received | |
224 | * when not in_syscall, then we want to return via syscall_exit_rfi, | |
225 | * not syscall_exit. Signal no. in r20, in_syscall in r25 (see | |
226 | * trampoline code in signal.c). | |
227 | */ | |
228 | ldi __NR_rt_sigreturn,%r2 | |
229 | comb,= %r2,%r20,.Lrt_sigreturn | |
230 | .Lin_syscall: | |
231 | ldil L%syscall_exit,%r2 | |
232 | be 0(%sr7,%r19) | |
233 | ldo R%syscall_exit(%r2),%r2 | |
234 | .Lrt_sigreturn: | |
235 | comib,<> 0,%r25,.Lin_syscall | |
236 | ldil L%syscall_exit_rfi,%r2 | |
237 | be 0(%sr7,%r19) | |
238 | ldo R%syscall_exit_rfi(%r2),%r2 | |
239 | ||
240 | /* Note! Because we are not running where we were linked, any | |
241 | calls to functions external to this file must be indirect. To | |
242 | be safe, we apply the opposite rule to functions within this | |
243 | file, with local labels given to them to ensure correctness. */ | |
244 | ||
245 | .Lsyscall_nosys: | |
246 | syscall_nosys: | |
247 | ldil L%syscall_exit,%r1 | |
248 | be R%syscall_exit(%sr7,%r1) | |
249 | ldo -ENOSYS(%r0),%r28 /* set errno */ | |
250 | ||
251 | ||
252 | /* Warning! This trace code is a virtual duplicate of the code above so be | |
253 | * sure to maintain both! */ | |
254 | .Ltracesys: | |
255 | tracesys: | |
256 | /* Need to save more registers so the debugger can see where we | |
257 | * are. This saves only the lower 8 bits of PSW, so that the C | |
258 | * bit is still clear on syscalls, and the D bit is set if this | |
259 | * full register save path has been executed. We check the D | |
260 | * bit on syscall_return_rfi to determine which registers to | |
261 | * restore. An interrupt results in a full PSW saved with the | |
262 | * C bit set, a non-straced syscall entry results in C and D clear | |
263 | * in the saved PSW. | |
264 | */ | |
265 | ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ | |
266 | LDREG TI_TASK(%r1), %r1 | |
267 | ssm 0,%r2 | |
268 | STREG %r2,TASK_PT_PSW(%r1) /* Lower 8 bits only!! */ | |
269 | mfsp %sr0,%r2 | |
270 | STREG %r2,TASK_PT_SR0(%r1) | |
271 | mfsp %sr1,%r2 | |
272 | STREG %r2,TASK_PT_SR1(%r1) | |
273 | mfsp %sr2,%r2 | |
274 | STREG %r2,TASK_PT_SR2(%r1) | |
275 | mfsp %sr3,%r2 | |
276 | STREG %r2,TASK_PT_SR3(%r1) | |
277 | STREG %r2,TASK_PT_SR4(%r1) | |
278 | STREG %r2,TASK_PT_SR5(%r1) | |
279 | STREG %r2,TASK_PT_SR6(%r1) | |
280 | STREG %r2,TASK_PT_SR7(%r1) | |
281 | STREG %r2,TASK_PT_IASQ0(%r1) | |
282 | STREG %r2,TASK_PT_IASQ1(%r1) | |
283 | LDREG TASK_PT_GR31(%r1),%r2 | |
284 | STREG %r2,TASK_PT_IAOQ0(%r1) | |
285 | ldo 4(%r2),%r2 | |
286 | STREG %r2,TASK_PT_IAOQ1(%r1) | |
287 | ldo TASK_REGS(%r1),%r2 | |
288 | /* reg_save %r2 */ | |
289 | STREG %r3,PT_GR3(%r2) | |
290 | STREG %r4,PT_GR4(%r2) | |
291 | STREG %r5,PT_GR5(%r2) | |
292 | STREG %r6,PT_GR6(%r2) | |
293 | STREG %r7,PT_GR7(%r2) | |
294 | STREG %r8,PT_GR8(%r2) | |
295 | STREG %r9,PT_GR9(%r2) | |
296 | STREG %r10,PT_GR10(%r2) | |
297 | STREG %r11,PT_GR11(%r2) | |
298 | STREG %r12,PT_GR12(%r2) | |
299 | STREG %r13,PT_GR13(%r2) | |
300 | STREG %r14,PT_GR14(%r2) | |
301 | STREG %r15,PT_GR15(%r2) | |
302 | STREG %r16,PT_GR16(%r2) | |
303 | STREG %r17,PT_GR17(%r2) | |
304 | STREG %r18,PT_GR18(%r2) | |
305 | /* Finished saving things for the debugger */ | |
306 | ||
307 | ldil L%syscall_trace,%r1 | |
308 | ldil L%tracesys_next,%r2 | |
309 | be R%syscall_trace(%sr7,%r1) | |
310 | ldo R%tracesys_next(%r2),%r2 | |
311 | ||
312 | tracesys_next: | |
313 | ldil L%sys_call_table,%r1 | |
314 | ldo R%sys_call_table(%r1), %r19 | |
315 | ||
316 | ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ | |
317 | LDREG TI_TASK(%r1), %r1 | |
318 | LDREG TASK_PT_GR20(%r1), %r20 | |
319 | LDREG TASK_PT_GR26(%r1), %r26 /* Restore the users args */ | |
320 | LDREG TASK_PT_GR25(%r1), %r25 | |
321 | LDREG TASK_PT_GR24(%r1), %r24 | |
322 | LDREG TASK_PT_GR23(%r1), %r23 | |
413059f2 | 323 | #ifdef CONFIG_64BIT |
1da177e4 LT |
324 | LDREG TASK_PT_GR22(%r1), %r22 |
325 | LDREG TASK_PT_GR21(%r1), %r21 | |
326 | ldo -16(%r30),%r29 /* Reference param save area */ | |
327 | #endif | |
328 | ||
329 | comiclr,>>= __NR_Linux_syscalls, %r20, %r0 | |
330 | b,n .Lsyscall_nosys | |
331 | ||
332 | LDREGX %r20(%r19), %r19 | |
333 | ||
334 | /* If this is a sys_rt_sigreturn call, and the signal was received | |
335 | * when not in_syscall, then we want to return via syscall_exit_rfi, | |
336 | * not syscall_exit. Signal no. in r20, in_syscall in r25 (see | |
337 | * trampoline code in signal.c). | |
338 | */ | |
339 | ldi __NR_rt_sigreturn,%r2 | |
340 | comb,= %r2,%r20,.Ltrace_rt_sigreturn | |
341 | .Ltrace_in_syscall: | |
342 | ldil L%tracesys_exit,%r2 | |
343 | be 0(%sr7,%r19) | |
344 | ldo R%tracesys_exit(%r2),%r2 | |
345 | ||
346 | /* Do *not* call this function on the gateway page, because it | |
347 | makes a direct call to syscall_trace. */ | |
348 | ||
349 | tracesys_exit: | |
350 | ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ | |
351 | LDREG TI_TASK(%r1), %r1 | |
413059f2 | 352 | #ifdef CONFIG_64BIT |
1da177e4 LT |
353 | ldo -16(%r30),%r29 /* Reference param save area */ |
354 | #endif | |
355 | bl syscall_trace, %r2 | |
356 | STREG %r28,TASK_PT_GR28(%r1) /* save return value now */ | |
357 | ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ | |
358 | LDREG TI_TASK(%r1), %r1 | |
359 | LDREG TASK_PT_GR28(%r1), %r28 /* Restore return val. */ | |
360 | ||
361 | ldil L%syscall_exit,%r1 | |
362 | be,n R%syscall_exit(%sr7,%r1) | |
363 | ||
364 | .Ltrace_rt_sigreturn: | |
365 | comib,<> 0,%r25,.Ltrace_in_syscall | |
366 | ldil L%tracesys_sigexit,%r2 | |
367 | be 0(%sr7,%r19) | |
368 | ldo R%tracesys_sigexit(%r2),%r2 | |
369 | ||
370 | tracesys_sigexit: | |
371 | ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */ | |
372 | LDREG 0(%r1), %r1 | |
413059f2 | 373 | #ifdef CONFIG_64BIT |
1da177e4 LT |
374 | ldo -16(%r30),%r29 /* Reference param save area */ |
375 | #endif | |
376 | bl syscall_trace, %r2 | |
377 | nop | |
378 | ||
379 | ldil L%syscall_exit_rfi,%r1 | |
380 | be,n R%syscall_exit_rfi(%sr7,%r1) | |
381 | ||
382 | ||
383 | /********************************************************* | |
384 | Light-weight-syscall code | |
385 | ||
386 | r20 - lws number | |
387 | r26,r25,r24,r23,r22 - Input registers | |
388 | r28 - Function return register | |
389 | r21 - Error code. | |
390 | ||
391 | Scracth: Any of the above that aren't being | |
392 | currently used, including r1. | |
393 | ||
394 | Return pointer: r31 (Not usable) | |
395 | ||
396 | Error codes returned by entry path: | |
397 | ||
398 | ENOSYS - r20 was an invalid LWS number. | |
399 | ||
400 | *********************************************************/ | |
401 | lws_start: | |
402 | /* Gate and ensure we return to userspace */ | |
403 | gate .+8, %r0 | |
404 | depi 3, 31, 2, %r31 /* Ensure we return to userspace */ | |
405 | ||
413059f2 | 406 | #ifdef CONFIG_64BIT |
1da177e4 LT |
407 | /* FIXME: If we are a 64-bit kernel just |
408 | * turn this on unconditionally. | |
409 | */ | |
410 | ssm PSW_SM_W, %r1 | |
411 | extrd,u %r1,PSW_W_BIT,1,%r1 | |
412 | /* sp must be aligned on 4, so deposit the W bit setting into | |
413 | * the bottom of sp temporarily */ | |
414 | or,ev %r1,%r30,%r30 | |
415 | ||
416 | /* Clip LWS number to a 32-bit value always */ | |
417 | depdi 0, 31, 32, %r20 | |
418 | #endif | |
419 | ||
420 | /* Is the lws entry number valid? */ | |
421 | comiclr,>>= __NR_lws_entries, %r20, %r0 | |
422 | b,n lws_exit_nosys | |
423 | ||
424 | /* WARNING: Trashing sr2 and sr3 */ | |
425 | mfsp %sr7,%r1 /* get userspace into sr3 */ | |
426 | mtsp %r1,%sr3 | |
427 | mtsp %r0,%sr2 /* get kernel space into sr2 */ | |
428 | ||
429 | /* Load table start */ | |
430 | ldil L%lws_table, %r1 | |
431 | ldo R%lws_table(%r1), %r28 /* Scratch use of r28 */ | |
432 | LDREGX %r20(%sr2,r28), %r21 /* Scratch use of r21 */ | |
433 | ||
434 | /* Jump to lws, lws table pointers already relocated */ | |
435 | be,n 0(%sr2,%r21) | |
436 | ||
437 | lws_exit_nosys: | |
438 | ldo -ENOSYS(%r0),%r21 /* set errno */ | |
439 | /* Fall through: Return to userspace */ | |
440 | ||
441 | lws_exit: | |
413059f2 | 442 | #ifdef CONFIG_64BIT |
1da177e4 LT |
443 | /* decide whether to reset the wide mode bit |
444 | * | |
445 | * For a syscall, the W bit is stored in the lowest bit | |
446 | * of sp. Extract it and reset W if it is zero */ | |
447 | extrd,u,*<> %r30,63,1,%r1 | |
448 | rsm PSW_SM_W, %r0 | |
449 | /* now reset the lowest bit of sp if it was set */ | |
450 | xor %r30,%r1,%r30 | |
451 | #endif | |
452 | be,n 0(%sr3, %r31) | |
453 | ||
454 | ||
455 | ||
456 | /*************************************************** | |
457 | Implementing CAS as an atomic operation: | |
458 | ||
459 | %r26 - Address to examine | |
460 | %r25 - Old value to check (old) | |
461 | %r24 - New value to set (new) | |
462 | %r28 - Return prev through this register. | |
463 | %r21 - Kernel error code | |
464 | ||
465 | If debugging is DISabled: | |
466 | ||
467 | %r21 has the following meanings: | |
468 | ||
469 | EAGAIN - CAS is busy, ldcw failed, try again. | |
470 | EFAULT - Read or write failed. | |
471 | ||
472 | If debugging is enabled: | |
473 | ||
474 | EDEADLOCK - CAS called recursively. | |
475 | EAGAIN && r28 == 1 - CAS is busy. Lock contended. | |
476 | EAGAIN && r28 == 2 - CAS is busy. ldcw failed. | |
477 | EFAULT - Read or write failed. | |
478 | ||
479 | Scratch: r20, r28, r1 | |
480 | ||
481 | ****************************************************/ | |
482 | ||
483 | /* Do not enable LWS debugging */ | |
484 | #define ENABLE_LWS_DEBUG 0 | |
485 | ||
486 | /* ELF64 Process entry path */ | |
487 | lws_compare_and_swap64: | |
413059f2 | 488 | #ifdef CONFIG_64BIT |
1da177e4 LT |
489 | b,n lws_compare_and_swap |
490 | #else | |
491 | /* If we are not a 64-bit kernel, then we don't | |
492 | * implement having 64-bit input registers | |
493 | */ | |
494 | b,n lws_exit_nosys | |
495 | #endif | |
496 | ||
497 | /* ELF32 Process entry path */ | |
498 | lws_compare_and_swap32: | |
413059f2 | 499 | #ifdef CONFIG_64BIT |
1da177e4 LT |
500 | /* Clip all the input registers */ |
501 | depdi 0, 31, 32, %r26 | |
502 | depdi 0, 31, 32, %r25 | |
503 | depdi 0, 31, 32, %r24 | |
504 | #endif | |
505 | ||
506 | lws_compare_and_swap: | |
507 | #ifdef CONFIG_SMP | |
508 | /* Load start of lock table */ | |
509 | ldil L%lws_lock_start, %r20 | |
510 | ldo R%lws_lock_start(%r20), %r28 | |
511 | ||
512 | /* Extract four bits from r26 and hash lock (Bits 4-7) */ | |
513 | extru %r26, 27, 4, %r20 | |
514 | ||
515 | /* Find lock to use, the hash is either one of 0 to | |
516 | 15, multiplied by 16 (keep it 16-byte aligned) | |
517 | and add to the lock table offset. */ | |
518 | shlw %r20, 4, %r20 | |
519 | add %r20, %r28, %r20 | |
520 | ||
521 | # ifdef ENABLE_LWS_DEBUG | |
522 | /* | |
523 | DEBUG, check for deadlock! | |
524 | If the thread register values are the same | |
525 | then we were the one that locked it last and | |
526 | this is a recurisve call that will deadlock. | |
527 | We *must* giveup this call and fail. | |
528 | */ | |
529 | ldw 4(%sr2,%r20), %r28 /* Load thread register */ | |
aa0eecb0 | 530 | /* WARNING: If cr27 cycles to the same value we have problems */ |
1da177e4 LT |
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" | |
413059f2 | 611 | #ifdef CONFIG_64BIT |
1da177e4 LT |
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" | |
413059f2 | 622 | #ifdef CONFIG_64BIT |
1da177e4 LT |
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 */ | |
413059f2 | 641 | #ifdef CONFIG_64BIT |
1da177e4 LT |
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 | ||
413059f2 | 669 | #ifdef CONFIG_64BIT |
1da177e4 LT |
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 |