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1/*
2 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
3 *
4 * System call entry code / Linux gateway page
5 * Copyright (c) Matthew Wilcox 1999 <willy@infradead.org>
6 * Licensed under the GNU GPL.
7 * thanks to Philipp Rumpf, Mike Shaver and various others
8 * sorry about the wall, puffin..
9 */
10
11/*
12How does the Linux gateway page on PA-RISC work?
13------------------------------------------------
14The Linux gateway page on PA-RISC is "special".
15It actually has PAGE_GATEWAY bits set (this is linux terminology; in parisc
16terminology it's Execute, promote to PL0) in the page map. So anything
17executing on this page executes with kernel level privilege (there's more to it
18than that: to have this happen, you also have to use a branch with a ,gate
19completer to activate the privilege promotion). The upshot is that everything
20that runs on the gateway page runs at kernel privilege but with the current
21user process address space (although you have access to kernel space via %sr2).
22For the 0x100 syscall entry, we redo the space registers to point to the kernel
23address space (preserving the user address space in %sr3), move to wide mode if
24required, save the user registers and branch into the kernel syscall entry
25point. For all the other functions, we execute at kernel privilege but don't
26flip address spaces. The basic upshot of this is that these code snippets are
27executed atomically (because the kernel can't be pre-empted) and they may
28perform architecturally forbidden (to PL3) operations (like setting control
29registers).
30*/
31
32
33#include <asm/asm-offsets.h>
34#include <asm/unistd.h>
35#include <asm/errno.h>
36#include <asm/page.h>
37#include <asm/psw.h>
38#include <asm/thread_info.h>
39#include <asm/assembly.h>
40#include <asm/processor.h>
41#include <asm/cache.h>
42
43#include <linux/linkage.h>
44
45 /* We fill the empty parts of the gateway page with
46 * something that will kill the kernel or a
47 * userspace application.
48 */
49#define KILL_INSN break 0,0
50
51 .level PA_ASM_LEVEL
52
53 .text
54
55 .import syscall_exit,code
56 .import syscall_exit_rfi,code
57
58 /* Linux gateway page is aliased to virtual page 0 in the kernel
59 * address space. Since it is a gateway page it cannot be
60 * dereferenced, so null pointers will still fault. We start
61 * the actual entry point at 0x100. We put break instructions
62 * at the beginning of the page to trap null indirect function
63 * pointers.
64 */
65
66 .align PAGE_SIZE
67ENTRY(linux_gateway_page)
68
69 /* ADDRESS 0x00 to 0xb0 = 176 bytes / 4 bytes per insn = 44 insns */
70 .rept 44
71 KILL_INSN
72 .endr
73
74 /* ADDRESS 0xb0 to 0xb8, lws uses two insns for entry */
75 /* Light-weight-syscall entry must always be located at 0xb0 */
76 /* WARNING: Keep this number updated with table size changes */
77#define __NR_lws_entries (3)
78
79lws_entry:
80 gate lws_start, %r0 /* increase privilege */
81 depi 3, 31, 2, %r31 /* Ensure we return into user mode. */
82
83 /* Fill from 0xb8 to 0xe0 */
84 .rept 10
85 KILL_INSN
86 .endr
87
88 /* This function MUST be located at 0xe0 for glibc's threading
89 mechanism to work. DO NOT MOVE THIS CODE EVER! */
90set_thread_pointer:
91 gate .+8, %r0 /* increase privilege */
92 depi 3, 31, 2, %r31 /* Ensure we return into user mode. */
93 be 0(%sr7,%r31) /* return to user space */
94 mtctl %r26, %cr27 /* move arg0 to the control register */
95
96 /* Increase the chance of trapping if random jumps occur to this
97 address, fill from 0xf0 to 0x100 */
98 .rept 4
99 KILL_INSN
100 .endr
101
102/* This address must remain fixed at 0x100 for glibc's syscalls to work */
103 .align LINUX_GATEWAY_ADDR
104linux_gateway_entry:
105 gate .+8, %r0 /* become privileged */
106 mtsp %r0,%sr4 /* get kernel space into sr4 */
107 mtsp %r0,%sr5 /* get kernel space into sr5 */
108 mtsp %r0,%sr6 /* get kernel space into sr6 */
109
110#ifdef CONFIG_64BIT
111 /* Store W bit on entry to the syscall in case it's a wide userland
112 * process. */
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
1281:
129#endif
130
131 /* We use a rsm/ssm pair to prevent sr3 from being clobbered
132 * by external interrupts.
133 */
134 mfsp %sr7,%r1 /* save user sr7 */
135 rsm PSW_SM_I, %r0 /* disable interrupts */
136 mtsp %r1,%sr3 /* and store it in sr3 */
137
138 mfctl %cr30,%r1
139 xor %r1,%r30,%r30 /* ye olde xor trick */
140 xor %r1,%r30,%r1
141 xor %r1,%r30,%r30
142
143 ldo THREAD_SZ_ALGN+FRAME_SIZE(%r30),%r30 /* set up kernel stack */
144
145 /* N.B.: It is critical that we don't set sr7 to 0 until r30
146 * contains a valid kernel stack pointer. It is also
147 * critical that we don't start using the kernel stack
148 * until after sr7 has been set to 0.
149 */
150
151 mtsp %r0,%sr7 /* get kernel space into sr7 */
152 ssm PSW_SM_I, %r0 /* enable interrupts */
153 STREGM %r1,FRAME_SIZE(%r30) /* save r1 (usp) here for now */
154 mfctl %cr30,%r1 /* get task ptr in %r1 */
155 LDREG TI_TASK(%r1),%r1
156
157 /* Save some registers for sigcontext and potential task
158 switch (see entry.S for the details of which ones are
159 saved/restored). TASK_PT_PSW is zeroed so we can see whether
160 a process is on a syscall or not. For an interrupt the real
161 PSW value is stored. This is needed for gdb and sys_ptrace. */
162 STREG %r0, TASK_PT_PSW(%r1)
163 STREG %r2, TASK_PT_GR2(%r1) /* preserve rp */
164 STREG %r19, TASK_PT_GR19(%r1)
165
166 LDREGM -FRAME_SIZE(%r30), %r2 /* get users sp back */
167#ifdef CONFIG_64BIT
168 extrd,u %r2,63,1,%r19 /* W hidden in bottom bit */
169#if 0
170 xor %r19,%r2,%r2 /* clear bottom bit */
171 depd,z %r19,1,1,%r19
172 std %r19,TASK_PT_PSW(%r1)
173#endif
174#endif
175 STREG %r2, TASK_PT_GR30(%r1) /* ... and save it */
176
177 STREG %r20, TASK_PT_GR20(%r1) /* Syscall number */
178 STREG %r21, TASK_PT_GR21(%r1)
179 STREG %r22, TASK_PT_GR22(%r1)
180 STREG %r23, TASK_PT_GR23(%r1) /* 4th argument */
181 STREG %r24, TASK_PT_GR24(%r1) /* 3rd argument */
182 STREG %r25, TASK_PT_GR25(%r1) /* 2nd argument */
183 STREG %r26, TASK_PT_GR26(%r1) /* 1st argument */
184 STREG %r27, TASK_PT_GR27(%r1) /* user dp */
185 STREG %r28, TASK_PT_GR28(%r1) /* return value 0 */
186 STREG %r0, TASK_PT_ORIG_R28(%r1) /* don't prohibit restarts */
187 STREG %r29, TASK_PT_GR29(%r1) /* return value 1 */
188 STREG %r31, TASK_PT_GR31(%r1) /* preserve syscall return ptr */
189
190 ldo TASK_PT_FR0(%r1), %r27 /* save fpregs from the kernel */
191 save_fp %r27 /* or potential task switch */
192
193 mfctl %cr11, %r27 /* i.e. SAR */
194 STREG %r27, TASK_PT_SAR(%r1)
195
196 loadgp
197
198#ifdef CONFIG_64BIT
199 ldo -16(%r30),%r29 /* Reference param save area */
200 copy %r19,%r2 /* W bit back to r2 */
201#else
202 /* no need to save these on stack in wide mode because the first 8
203 * args are passed in registers */
204 stw %r22, -52(%r30) /* 5th argument */
205 stw %r21, -56(%r30) /* 6th argument */
206#endif
207
208 /* Are we being ptraced? */
209 mfctl %cr30, %r1
210 LDREG TI_FLAGS(%r1),%r1
211 ldi _TIF_SYSCALL_TRACE_MASK, %r19
212 and,COND(=) %r1, %r19, %r0
213 b,n .Ltracesys
214
215 /* Note! We cannot use the syscall table that is mapped
216 nearby since the gateway page is mapped execute-only. */
217
218#ifdef CONFIG_64BIT
219 ldil L%sys_call_table, %r1
220 or,= %r2,%r2,%r2
221 addil L%(sys_call_table64-sys_call_table), %r1
222 ldo R%sys_call_table(%r1), %r19
223 or,= %r2,%r2,%r2
224 ldo R%sys_call_table64(%r1), %r19
225#else
226 load32 sys_call_table, %r19
227#endif
228 comiclr,>> __NR_Linux_syscalls, %r20, %r0
229 b,n .Lsyscall_nosys
230
231 LDREGX %r20(%r19), %r19
232
233 /* If this is a sys_rt_sigreturn call, and the signal was received
234 * when not in_syscall, then we want to return via syscall_exit_rfi,
235 * not syscall_exit. Signal no. in r20, in_syscall in r25 (see
236 * trampoline code in signal.c).
237 */
238 ldi __NR_rt_sigreturn,%r2
239 comb,= %r2,%r20,.Lrt_sigreturn
240.Lin_syscall:
241 ldil L%syscall_exit,%r2
242 be 0(%sr7,%r19)
243 ldo R%syscall_exit(%r2),%r2
244.Lrt_sigreturn:
245 comib,<> 0,%r25,.Lin_syscall
246 ldil L%syscall_exit_rfi,%r2
247 be 0(%sr7,%r19)
248 ldo R%syscall_exit_rfi(%r2),%r2
249
250 /* Note! Because we are not running where we were linked, any
251 calls to functions external to this file must be indirect. To
252 be safe, we apply the opposite rule to functions within this
253 file, with local labels given to them to ensure correctness. */
254
255.Lsyscall_nosys:
256syscall_nosys:
257 ldil L%syscall_exit,%r1
258 be R%syscall_exit(%sr7,%r1)
259 ldo -ENOSYS(%r0),%r28 /* set errno */
260
261
262/* Warning! This trace code is a virtual duplicate of the code above so be
263 * sure to maintain both! */
264.Ltracesys:
265tracesys:
266 /* Need to save more registers so the debugger can see where we
267 * are. This saves only the lower 8 bits of PSW, so that the C
268 * bit is still clear on syscalls, and the D bit is set if this
269 * full register save path has been executed. We check the D
270 * bit on syscall_return_rfi to determine which registers to
271 * restore. An interrupt results in a full PSW saved with the
272 * C bit set, a non-straced syscall entry results in C and D clear
273 * in the saved PSW.
274 */
275 ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
276 LDREG TI_TASK(%r1), %r1
277 ssm 0,%r2
278 STREG %r2,TASK_PT_PSW(%r1) /* Lower 8 bits only!! */
279 mfsp %sr0,%r2
280 STREG %r2,TASK_PT_SR0(%r1)
281 mfsp %sr1,%r2
282 STREG %r2,TASK_PT_SR1(%r1)
283 mfsp %sr2,%r2
284 STREG %r2,TASK_PT_SR2(%r1)
285 mfsp %sr3,%r2
286 STREG %r2,TASK_PT_SR3(%r1)
287 STREG %r2,TASK_PT_SR4(%r1)
288 STREG %r2,TASK_PT_SR5(%r1)
289 STREG %r2,TASK_PT_SR6(%r1)
290 STREG %r2,TASK_PT_SR7(%r1)
291 STREG %r2,TASK_PT_IASQ0(%r1)
292 STREG %r2,TASK_PT_IASQ1(%r1)
293 LDREG TASK_PT_GR31(%r1),%r2
294 STREG %r2,TASK_PT_IAOQ0(%r1)
295 ldo 4(%r2),%r2
296 STREG %r2,TASK_PT_IAOQ1(%r1)
297 ldo TASK_REGS(%r1),%r2
298 /* reg_save %r2 */
299 STREG %r3,PT_GR3(%r2)
300 STREG %r4,PT_GR4(%r2)
301 STREG %r5,PT_GR5(%r2)
302 STREG %r6,PT_GR6(%r2)
303 STREG %r7,PT_GR7(%r2)
304 STREG %r8,PT_GR8(%r2)
305 STREG %r9,PT_GR9(%r2)
306 STREG %r10,PT_GR10(%r2)
307 STREG %r11,PT_GR11(%r2)
308 STREG %r12,PT_GR12(%r2)
309 STREG %r13,PT_GR13(%r2)
310 STREG %r14,PT_GR14(%r2)
311 STREG %r15,PT_GR15(%r2)
312 STREG %r16,PT_GR16(%r2)
313 STREG %r17,PT_GR17(%r2)
314 STREG %r18,PT_GR18(%r2)
315 /* Finished saving things for the debugger */
316
317 copy %r2,%r26
318 ldil L%do_syscall_trace_enter,%r1
319 ldil L%tracesys_next,%r2
320 be R%do_syscall_trace_enter(%sr7,%r1)
321 ldo R%tracesys_next(%r2),%r2
322
323tracesys_next:
324 /* do_syscall_trace_enter either returned the syscallno, or -1L,
325 * so we skip restoring the PT_GR20 below, since we pulled it from
326 * task->thread.regs.gr[20] above.
327 */
328 copy %ret0,%r20
329
330 ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
331 LDREG TI_TASK(%r1), %r1
332 LDREG TASK_PT_GR28(%r1), %r28 /* Restore return value */
333 LDREG TASK_PT_GR26(%r1), %r26 /* Restore the users args */
334 LDREG TASK_PT_GR25(%r1), %r25
335 LDREG TASK_PT_GR24(%r1), %r24
336 LDREG TASK_PT_GR23(%r1), %r23
337 LDREG TASK_PT_GR22(%r1), %r22
338 LDREG TASK_PT_GR21(%r1), %r21
339#ifdef CONFIG_64BIT
340 ldo -16(%r30),%r29 /* Reference param save area */
341#else
342 stw %r22, -52(%r30) /* 5th argument */
343 stw %r21, -56(%r30) /* 6th argument */
344#endif
345
346 cmpib,COND(=),n -1,%r20,tracesys_exit /* seccomp may have returned -1 */
347 comiclr,>> __NR_Linux_syscalls, %r20, %r0
348 b,n .Ltracesys_nosys
349
350 /* Note! We cannot use the syscall table that is mapped
351 nearby since the gateway page is mapped execute-only. */
352
353#ifdef CONFIG_64BIT
354 LDREG TASK_PT_GR30(%r1), %r19 /* get users sp back */
355 extrd,u %r19,63,1,%r2 /* W hidden in bottom bit */
356
357 ldil L%sys_call_table, %r1
358 or,= %r2,%r2,%r2
359 addil L%(sys_call_table64-sys_call_table), %r1
360 ldo R%sys_call_table(%r1), %r19
361 or,= %r2,%r2,%r2
362 ldo R%sys_call_table64(%r1), %r19
363#else
364 load32 sys_call_table, %r19
365#endif
366
367 LDREGX %r20(%r19), %r19
368
369 /* If this is a sys_rt_sigreturn call, and the signal was received
370 * when not in_syscall, then we want to return via syscall_exit_rfi,
371 * not syscall_exit. Signal no. in r20, in_syscall in r25 (see
372 * trampoline code in signal.c).
373 */
374 ldi __NR_rt_sigreturn,%r2
375 comb,= %r2,%r20,.Ltrace_rt_sigreturn
376.Ltrace_in_syscall:
377 ldil L%tracesys_exit,%r2
378 be 0(%sr7,%r19)
379 ldo R%tracesys_exit(%r2),%r2
380
381.Ltracesys_nosys:
382 ldo -ENOSYS(%r0),%r28 /* set errno */
383
384 /* Do *not* call this function on the gateway page, because it
385 makes a direct call to syscall_trace. */
386
387tracesys_exit:
388 ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
389 LDREG TI_TASK(%r1), %r1
390#ifdef CONFIG_64BIT
391 ldo -16(%r30),%r29 /* Reference param save area */
392#endif
393 ldo TASK_REGS(%r1),%r26
394 BL do_syscall_trace_exit,%r2
395 STREG %r28,TASK_PT_GR28(%r1) /* save return value now */
396 ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
397 LDREG TI_TASK(%r1), %r1
398 LDREG TASK_PT_GR28(%r1), %r28 /* Restore return val. */
399
400 ldil L%syscall_exit,%r1
401 be,n R%syscall_exit(%sr7,%r1)
402
403.Ltrace_rt_sigreturn:
404 comib,<> 0,%r25,.Ltrace_in_syscall
405 ldil L%tracesys_sigexit,%r2
406 be 0(%sr7,%r19)
407 ldo R%tracesys_sigexit(%r2),%r2
408
409tracesys_sigexit:
410 ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
411 LDREG TI_TASK(%r1), %r1
412#ifdef CONFIG_64BIT
413 ldo -16(%r30),%r29 /* Reference param save area */
414#endif
415 BL do_syscall_trace_exit,%r2
416 ldo TASK_REGS(%r1),%r26
417
418 ldil L%syscall_exit_rfi,%r1
419 be,n R%syscall_exit_rfi(%sr7,%r1)
420
421
422 /*********************************************************
423 32/64-bit Light-Weight-Syscall ABI
424
425 * - Indicates a hint for userspace inline asm
426 implementations.
427
428 Syscall number (caller-saves)
429 - %r20
430 * In asm clobber.
431
432 Argument registers (caller-saves)
433 - %r26, %r25, %r24, %r23, %r22
434 * In asm input.
435
436 Return registers (caller-saves)
437 - %r28 (return), %r21 (errno)
438 * In asm output.
439
440 Caller-saves registers
441 - %r1, %r27, %r29
442 - %r2 (return pointer)
443 - %r31 (ble link register)
444 * In asm clobber.
445
446 Callee-saves registers
447 - %r3-%r18
448 - %r30 (stack pointer)
449 * Not in asm clobber.
450
451 If userspace is 32-bit:
452 Callee-saves registers
453 - %r19 (32-bit PIC register)
454
455 Differences from 32-bit calling convention:
456 - Syscall number in %r20
457 - Additional argument register %r22 (arg4)
458 - Callee-saves %r19.
459
460 If userspace is 64-bit:
461 Callee-saves registers
462 - %r27 (64-bit PIC register)
463
464 Differences from 64-bit calling convention:
465 - Syscall number in %r20
466 - Additional argument register %r22 (arg4)
467 - Callee-saves %r27.
468
469 Error codes returned by entry path:
470
471 ENOSYS - r20 was an invalid LWS number.
472
473 *********************************************************/
474lws_start:
475
476#ifdef CONFIG_64BIT
477 ssm PSW_SM_W, %r1
478 extrd,u %r1,PSW_W_BIT,1,%r1
479 /* sp must be aligned on 4, so deposit the W bit setting into
480 * the bottom of sp temporarily */
481 or,ev %r1,%r30,%r30
482
483 /* Clip LWS number to a 32-bit value for 32-bit processes */
484 depdi 0, 31, 32, %r20
485#endif
486
487 /* Is the lws entry number valid? */
488 comiclr,>> __NR_lws_entries, %r20, %r0
489 b,n lws_exit_nosys
490
491 /* Load table start */
492 ldil L%lws_table, %r1
493 ldo R%lws_table(%r1), %r28 /* Scratch use of r28 */
494 LDREGX %r20(%sr2,r28), %r21 /* Scratch use of r21 */
495
496 /* Jump to lws, lws table pointers already relocated */
497 be,n 0(%sr2,%r21)
498
499lws_exit_nosys:
500 ldo -ENOSYS(%r0),%r21 /* set errno */
501 /* Fall through: Return to userspace */
502
503lws_exit:
504#ifdef CONFIG_64BIT
505 /* decide whether to reset the wide mode bit
506 *
507 * For a syscall, the W bit is stored in the lowest bit
508 * of sp. Extract it and reset W if it is zero */
509 extrd,u,*<> %r30,63,1,%r1
510 rsm PSW_SM_W, %r0
511 /* now reset the lowest bit of sp if it was set */
512 xor %r30,%r1,%r30
513#endif
514 be,n 0(%sr7, %r31)
515
516
517
518 /***************************************************
519 Implementing 32bit CAS as an atomic operation:
520
521 %r26 - Address to examine
522 %r25 - Old value to check (old)
523 %r24 - New value to set (new)
524 %r28 - Return prev through this register.
525 %r21 - Kernel error code
526
527 If debugging is DISabled:
528
529 %r21 has the following meanings:
530
531 EAGAIN - CAS is busy, ldcw failed, try again.
532 EFAULT - Read or write failed.
533
534 If debugging is enabled:
535
536 EDEADLOCK - CAS called recursively.
537 EAGAIN && r28 == 1 - CAS is busy. Lock contended.
538 EAGAIN && r28 == 2 - CAS is busy. ldcw failed.
539 EFAULT - Read or write failed.
540
541 Scratch: r20, r28, r1
542
543 ****************************************************/
544
545 /* Do not enable LWS debugging */
546#define ENABLE_LWS_DEBUG 0
547
548 /* ELF64 Process entry path */
549lws_compare_and_swap64:
550#ifdef CONFIG_64BIT
551 b,n lws_compare_and_swap
552#else
553 /* If we are not a 64-bit kernel, then we don't
554 * have 64-bit input registers, and calling
555 * the 64-bit LWS CAS returns ENOSYS.
556 */
557 b,n lws_exit_nosys
558#endif
559
560 /* ELF32 Process entry path */
561lws_compare_and_swap32:
562#ifdef CONFIG_64BIT
563 /* Clip all the input registers */
564 depdi 0, 31, 32, %r26
565 depdi 0, 31, 32, %r25
566 depdi 0, 31, 32, %r24
567#endif
568
569lws_compare_and_swap:
570 /* Load start of lock table */
571 ldil L%lws_lock_start, %r20
572 ldo R%lws_lock_start(%r20), %r28
573
574 /* Extract four bits from r26 and hash lock (Bits 4-7) */
575 extru %r26, 27, 4, %r20
576
577 /* Find lock to use, the hash is either one of 0 to
578 15, multiplied by 16 (keep it 16-byte aligned)
579 and add to the lock table offset. */
580 shlw %r20, 4, %r20
581 add %r20, %r28, %r20
582
583# if ENABLE_LWS_DEBUG
584 /*
585 DEBUG, check for deadlock!
586 If the thread register values are the same
587 then we were the one that locked it last and
588 this is a recurisve call that will deadlock.
589 We *must* giveup this call and fail.
590 */
591 ldw 4(%sr2,%r20), %r28 /* Load thread register */
592 /* WARNING: If cr27 cycles to the same value we have problems */
593 mfctl %cr27, %r21 /* Get current thread register */
594 cmpb,<>,n %r21, %r28, cas_lock /* Called recursive? */
595 b lws_exit /* Return error! */
596 ldo -EDEADLOCK(%r0), %r21
597cas_lock:
598 cmpb,=,n %r0, %r28, cas_nocontend /* Is nobody using it? */
599 ldo 1(%r0), %r28 /* 1st case */
600 b lws_exit /* Contended... */
601 ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
602cas_nocontend:
603# endif
604/* ENABLE_LWS_DEBUG */
605
606 rsm PSW_SM_I, %r0 /* Disable interrupts */
607 /* COW breaks can cause contention on UP systems */
608 LDCW 0(%sr2,%r20), %r28 /* Try to acquire the lock */
609 cmpb,<>,n %r0, %r28, cas_action /* Did we get it? */
610cas_wouldblock:
611 ldo 2(%r0), %r28 /* 2nd case */
612 ssm PSW_SM_I, %r0
613 b lws_exit /* Contended... */
614 ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
615
616 /*
617 prev = *addr;
618 if ( prev == old )
619 *addr = new;
620 return prev;
621 */
622
623 /* NOTES:
624 This all works becuse intr_do_signal
625 and schedule both check the return iasq
626 and see that we are on the kernel page
627 so this process is never scheduled off
628 or is ever sent any signal of any sort,
629 thus it is wholly atomic from usrspaces
630 perspective
631 */
632cas_action:
633#if defined CONFIG_SMP && ENABLE_LWS_DEBUG
634 /* DEBUG */
635 mfctl %cr27, %r1
636 stw %r1, 4(%sr2,%r20)
637#endif
638 /* The load and store could fail */
6391: ldw 0(%r26), %r28
640 sub,<> %r28, %r25, %r0
6412: stw %r24, 0(%r26)
642 /* Free lock */
643#ifdef CONFIG_SMP
64498: LDCW 0(%sr2,%r20), %r1 /* Barrier */
64599: ALTERNATIVE(98b, 99b, ALT_COND_NO_SMP, INSN_NOP)
646#endif
647 stw %r20, 0(%sr2,%r20)
648#if ENABLE_LWS_DEBUG
649 /* Clear thread register indicator */
650 stw %r0, 4(%sr2,%r20)
651#endif
652 /* Enable interrupts */
653 ssm PSW_SM_I, %r0
654 /* Return to userspace, set no error */
655 b lws_exit
656 copy %r0, %r21
657
6583:
659 /* Error occurred on load or store */
660 /* Free lock */
661#ifdef CONFIG_SMP
66298: LDCW 0(%sr2,%r20), %r1 /* Barrier */
66399: ALTERNATIVE(98b, 99b, ALT_COND_NO_SMP, INSN_NOP)
664#endif
665 stw %r20, 0(%sr2,%r20)
666#if ENABLE_LWS_DEBUG
667 stw %r0, 4(%sr2,%r20)
668#endif
669 ssm PSW_SM_I, %r0
670 b lws_exit
671 ldo -EFAULT(%r0),%r21 /* set errno */
672 nop
673 nop
674 nop
675 nop
676
677 /* Two exception table entries, one for the load,
678 the other for the store. Either return -EFAULT.
679 Each of the entries must be relocated. */
680 ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 3b-linux_gateway_page)
681 ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 3b-linux_gateway_page)
682
683
684 /***************************************************
685 New CAS implementation which uses pointers and variable size
686 information. The value pointed by old and new MUST NOT change
687 while performing CAS. The lock only protect the value at %r26.
688
689 %r26 - Address to examine
690 %r25 - Pointer to the value to check (old)
691 %r24 - Pointer to the value to set (new)
692 %r23 - Size of the variable (0/1/2/3 for 8/16/32/64 bit)
693 %r28 - Return non-zero on failure
694 %r21 - Kernel error code
695
696 %r21 has the following meanings:
697
698 EAGAIN - CAS is busy, ldcw failed, try again.
699 EFAULT - Read or write failed.
700
701 Scratch: r20, r22, r28, r29, r1, fr4 (32bit for 64bit CAS only)
702
703 ****************************************************/
704
705 /* ELF32 Process entry path */
706lws_compare_and_swap_2:
707#ifdef CONFIG_64BIT
708 /* Clip the input registers. We don't need to clip %r23 as we
709 only use it for word operations */
710 depdi 0, 31, 32, %r26
711 depdi 0, 31, 32, %r25
712 depdi 0, 31, 32, %r24
713#endif
714
715 /* Check the validity of the size pointer */
716 subi,>>= 3, %r23, %r0
717 b,n lws_exit_nosys
718
719 /* Jump to the functions which will load the old and new values into
720 registers depending on the their size */
721 shlw %r23, 2, %r29
722 blr %r29, %r0
723 nop
724
725 /* 8bit load */
7264: ldb 0(%r25), %r25
727 b cas2_lock_start
7285: ldb 0(%r24), %r24
729 nop
730 nop
731 nop
732 nop
733 nop
734
735 /* 16bit load */
7366: ldh 0(%r25), %r25
737 b cas2_lock_start
7387: ldh 0(%r24), %r24
739 nop
740 nop
741 nop
742 nop
743 nop
744
745 /* 32bit load */
7468: ldw 0(%r25), %r25
747 b cas2_lock_start
7489: ldw 0(%r24), %r24
749 nop
750 nop
751 nop
752 nop
753 nop
754
755 /* 64bit load */
756#ifdef CONFIG_64BIT
75710: ldd 0(%r25), %r25
75811: ldd 0(%r24), %r24
759#else
760 /* Load old value into r22/r23 - high/low */
76110: ldw 0(%r25), %r22
76211: ldw 4(%r25), %r23
763 /* Load new value into fr4 for atomic store later */
76412: flddx 0(%r24), %fr4
765#endif
766
767cas2_lock_start:
768 /* Load start of lock table */
769 ldil L%lws_lock_start, %r20
770 ldo R%lws_lock_start(%r20), %r28
771
772 /* Extract four bits from r26 and hash lock (Bits 4-7) */
773 extru %r26, 27, 4, %r20
774
775 /* Find lock to use, the hash is either one of 0 to
776 15, multiplied by 16 (keep it 16-byte aligned)
777 and add to the lock table offset. */
778 shlw %r20, 4, %r20
779 add %r20, %r28, %r20
780
781 rsm PSW_SM_I, %r0 /* Disable interrupts */
782 /* COW breaks can cause contention on UP systems */
783 LDCW 0(%sr2,%r20), %r28 /* Try to acquire the lock */
784 cmpb,<>,n %r0, %r28, cas2_action /* Did we get it? */
785cas2_wouldblock:
786 ldo 2(%r0), %r28 /* 2nd case */
787 ssm PSW_SM_I, %r0
788 b lws_exit /* Contended... */
789 ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
790
791 /*
792 prev = *addr;
793 if ( prev == old )
794 *addr = new;
795 return prev;
796 */
797
798 /* NOTES:
799 This all works becuse intr_do_signal
800 and schedule both check the return iasq
801 and see that we are on the kernel page
802 so this process is never scheduled off
803 or is ever sent any signal of any sort,
804 thus it is wholly atomic from usrspaces
805 perspective
806 */
807cas2_action:
808 /* Jump to the correct function */
809 blr %r29, %r0
810 /* Set %r28 as non-zero for now */
811 ldo 1(%r0),%r28
812
813 /* 8bit CAS */
81413: ldb 0(%r26), %r29
815 sub,= %r29, %r25, %r0
816 b,n cas2_end
81714: stb %r24, 0(%r26)
818 b cas2_end
819 copy %r0, %r28
820 nop
821 nop
822
823 /* 16bit CAS */
82415: ldh 0(%r26), %r29
825 sub,= %r29, %r25, %r0
826 b,n cas2_end
82716: sth %r24, 0(%r26)
828 b cas2_end
829 copy %r0, %r28
830 nop
831 nop
832
833 /* 32bit CAS */
83417: ldw 0(%r26), %r29
835 sub,= %r29, %r25, %r0
836 b,n cas2_end
83718: stw %r24, 0(%r26)
838 b cas2_end
839 copy %r0, %r28
840 nop
841 nop
842
843 /* 64bit CAS */
844#ifdef CONFIG_64BIT
84519: ldd 0(%r26), %r29
846 sub,*= %r29, %r25, %r0
847 b,n cas2_end
84820: std %r24, 0(%r26)
849 copy %r0, %r28
850#else
851 /* Compare first word */
85219: ldw 0(%r26), %r29
853 sub,= %r29, %r22, %r0
854 b,n cas2_end
855 /* Compare second word */
85620: ldw 4(%r26), %r29
857 sub,= %r29, %r23, %r0
858 b,n cas2_end
859 /* Perform the store */
86021: fstdx %fr4, 0(%r26)
861 copy %r0, %r28
862#endif
863
864cas2_end:
865 /* Free lock */
866#ifdef CONFIG_SMP
86798: LDCW 0(%sr2,%r20), %r1 /* Barrier */
86899: ALTERNATIVE(98b, 99b, ALT_COND_NO_SMP, INSN_NOP)
869#endif
870 stw %r20, 0(%sr2,%r20)
871 /* Enable interrupts */
872 ssm PSW_SM_I, %r0
873 /* Return to userspace, set no error */
874 b lws_exit
875 copy %r0, %r21
876
87722:
878 /* Error occurred on load or store */
879 /* Free lock */
880#ifdef CONFIG_SMP
88198: LDCW 0(%sr2,%r20), %r1 /* Barrier */
88299: ALTERNATIVE(98b, 99b, ALT_COND_NO_SMP, INSN_NOP)
883#endif
884 stw %r20, 0(%sr2,%r20)
885 ssm PSW_SM_I, %r0
886 ldo 1(%r0),%r28
887 b lws_exit
888 ldo -EFAULT(%r0),%r21 /* set errno */
889 nop
890 nop
891 nop
892
893 /* Exception table entries, for the load and store, return EFAULT.
894 Each of the entries must be relocated. */
895 ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 22b-linux_gateway_page)
896 ASM_EXCEPTIONTABLE_ENTRY(5b-linux_gateway_page, 22b-linux_gateway_page)
897 ASM_EXCEPTIONTABLE_ENTRY(6b-linux_gateway_page, 22b-linux_gateway_page)
898 ASM_EXCEPTIONTABLE_ENTRY(7b-linux_gateway_page, 22b-linux_gateway_page)
899 ASM_EXCEPTIONTABLE_ENTRY(8b-linux_gateway_page, 22b-linux_gateway_page)
900 ASM_EXCEPTIONTABLE_ENTRY(9b-linux_gateway_page, 22b-linux_gateway_page)
901 ASM_EXCEPTIONTABLE_ENTRY(10b-linux_gateway_page, 22b-linux_gateway_page)
902 ASM_EXCEPTIONTABLE_ENTRY(11b-linux_gateway_page, 22b-linux_gateway_page)
903 ASM_EXCEPTIONTABLE_ENTRY(13b-linux_gateway_page, 22b-linux_gateway_page)
904 ASM_EXCEPTIONTABLE_ENTRY(14b-linux_gateway_page, 22b-linux_gateway_page)
905 ASM_EXCEPTIONTABLE_ENTRY(15b-linux_gateway_page, 22b-linux_gateway_page)
906 ASM_EXCEPTIONTABLE_ENTRY(16b-linux_gateway_page, 22b-linux_gateway_page)
907 ASM_EXCEPTIONTABLE_ENTRY(17b-linux_gateway_page, 22b-linux_gateway_page)
908 ASM_EXCEPTIONTABLE_ENTRY(18b-linux_gateway_page, 22b-linux_gateway_page)
909 ASM_EXCEPTIONTABLE_ENTRY(19b-linux_gateway_page, 22b-linux_gateway_page)
910 ASM_EXCEPTIONTABLE_ENTRY(20b-linux_gateway_page, 22b-linux_gateway_page)
911#ifndef CONFIG_64BIT
912 ASM_EXCEPTIONTABLE_ENTRY(12b-linux_gateway_page, 22b-linux_gateway_page)
913 ASM_EXCEPTIONTABLE_ENTRY(21b-linux_gateway_page, 22b-linux_gateway_page)
914#endif
915
916 /* Make sure nothing else is placed on this page */
917 .align PAGE_SIZE
918END(linux_gateway_page)
919ENTRY(end_linux_gateway_page)
920
921 /* Relocate symbols assuming linux_gateway_page is mapped
922 to virtual address 0x0 */
923
924#define LWS_ENTRY(_name_) ASM_ULONG_INSN (lws_##_name_ - linux_gateway_page)
925
926 .section .rodata,"a"
927
928 .align 8
929 /* Light-weight-syscall table */
930 /* Start of lws table. */
931ENTRY(lws_table)
932 LWS_ENTRY(compare_and_swap32) /* 0 - ELF32 Atomic 32bit CAS */
933 LWS_ENTRY(compare_and_swap64) /* 1 - ELF64 Atomic 32bit CAS */
934 LWS_ENTRY(compare_and_swap_2) /* 2 - ELF32 Atomic 64bit CAS */
935END(lws_table)
936 /* End of lws table */
937
938#define __SYSCALL(nr, entry, nargs) ASM_ULONG_INSN entry
939 .align 8
940ENTRY(sys_call_table)
941 .export sys_call_table,data
942#ifdef CONFIG_64BIT
943#include <asm/syscall_table_c32.h> /* Compat syscalls */
944#else
945#include <asm/syscall_table_32.h> /* 32-bit native syscalls */
946#endif
947END(sys_call_table)
948
949#ifdef CONFIG_64BIT
950 .align 8
951ENTRY(sys_call_table64)
952#include <asm/syscall_table_64.h> /* 64-bit native syscalls */
953END(sys_call_table64)
954#endif
955#undef __SYSCALL
956
957 /*
958 All light-weight-syscall atomic operations
959 will use this set of locks
960
961 NOTE: The lws_lock_start symbol must be
962 at least 16-byte aligned for safe use
963 with ldcw.
964 */
965 .section .data
966 .align L1_CACHE_BYTES
967ENTRY(lws_lock_start)
968 /* lws locks */
969 .rept 16
970 /* Keep locks aligned at 16-bytes */
971 .word 1
972 .word 0
973 .word 0
974 .word 0
975 .endr
976END(lws_lock_start)
977 .previous
978
979.end
980
981
1/*
2 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
3 *
4 * System call entry code / Linux gateway page
5 * Copyright (c) Matthew Wilcox 1999 <willy@infradead.org>
6 * Licensed under the GNU GPL.
7 * thanks to Philipp Rumpf, Mike Shaver and various others
8 * sorry about the wall, puffin..
9 */
10
11/*
12How does the Linux gateway page on PA-RISC work?
13------------------------------------------------
14The Linux gateway page on PA-RISC is "special".
15It actually has PAGE_GATEWAY bits set (this is linux terminology; in parisc
16terminology it's Execute, promote to PL0) in the page map. So anything
17executing on this page executes with kernel level privilege (there's more to it
18than that: to have this happen, you also have to use a branch with a ,gate
19completer to activate the privilege promotion). The upshot is that everything
20that runs on the gateway page runs at kernel privilege but with the current
21user process address space (although you have access to kernel space via %sr2).
22For the 0x100 syscall entry, we redo the space registers to point to the kernel
23address space (preserving the user address space in %sr3), move to wide mode if
24required, save the user registers and branch into the kernel syscall entry
25point. For all the other functions, we execute at kernel privilege but don't
26flip address spaces. The basic upshot of this is that these code snippets are
27executed atomically (because the kernel can't be pre-empted) and they may
28perform architecturally forbidden (to PL3) operations (like setting control
29registers).
30*/
31
32
33#include <asm/asm-offsets.h>
34#include <asm/unistd.h>
35#include <asm/errno.h>
36#include <asm/page.h>
37#include <asm/psw.h>
38#include <asm/thread_info.h>
39#include <asm/assembly.h>
40#include <asm/processor.h>
41#include <asm/cache.h>
42#include <asm/spinlock_types.h>
43
44#include <linux/linkage.h>
45
46 /* We fill the empty parts of the gateway page with
47 * something that will kill the kernel or a
48 * userspace application.
49 */
50#define KILL_INSN break 0,0
51
52 .level PA_ASM_LEVEL
53
54 .macro lws_pagefault_disable reg1,reg2
55 mfctl %cr30, \reg2
56 ldo TASK_PAGEFAULT_DISABLED(\reg2), \reg2
57 ldw 0(%sr2,\reg2), \reg1
58 ldo 1(\reg1), \reg1
59 stw \reg1, 0(%sr2,\reg2)
60 .endm
61
62 .macro lws_pagefault_enable reg1,reg2
63 mfctl %cr30, \reg2
64 ldo TASK_PAGEFAULT_DISABLED(\reg2), \reg2
65 ldw 0(%sr2,\reg2), \reg1
66 ldo -1(\reg1), \reg1
67 stw \reg1, 0(%sr2,\reg2)
68 .endm
69
70 /* raise exception if spinlock content is not zero or
71 * __ARCH_SPIN_LOCK_UNLOCKED_VAL */
72 .macro spinlock_check spin_val,tmpreg
73#ifdef CONFIG_LIGHTWEIGHT_SPINLOCK_CHECK
74 ldi __ARCH_SPIN_LOCK_UNLOCKED_VAL, \tmpreg
75 andcm,= \spin_val, \tmpreg, %r0
76 .word SPINLOCK_BREAK_INSN
77#endif
78 .endm
79
80 .text
81
82 .import syscall_exit,code
83 .import syscall_exit_rfi,code
84
85 /* Linux gateway page is aliased to virtual page 0 in the kernel
86 * address space. Since it is a gateway page it cannot be
87 * dereferenced, so null pointers will still fault. We start
88 * the actual entry point at 0x100. We put break instructions
89 * at the beginning of the page to trap null indirect function
90 * pointers.
91 */
92
93 .align PAGE_SIZE
94ENTRY(linux_gateway_page)
95
96 /* ADDRESS 0x00 to 0xb0 = 176 bytes / 4 bytes per insn = 44 insns */
97 .rept 44
98 KILL_INSN
99 .endr
100
101 /* ADDRESS 0xb0 to 0xb8, lws uses two insns for entry */
102 /* Light-weight-syscall entry must always be located at 0xb0 */
103 /* WARNING: Keep this number updated with table size changes */
104#define __NR_lws_entries (5)
105
106lws_entry:
107 gate lws_start, %r0 /* increase privilege */
108 depi PRIV_USER, 31, 2, %r31 /* Ensure we return into user mode. */
109
110 /* Fill from 0xb8 to 0xe0 */
111 .rept 10
112 KILL_INSN
113 .endr
114
115 /* This function MUST be located at 0xe0 for glibc's threading
116 mechanism to work. DO NOT MOVE THIS CODE EVER! */
117set_thread_pointer:
118 gate .+8, %r0 /* increase privilege */
119 depi PRIV_USER, 31, 2, %r31 /* Ensure we return into user mode. */
120 be 0(%sr7,%r31) /* return to user space */
121 mtctl %r26, %cr27 /* move arg0 to the control register */
122
123 /* Increase the chance of trapping if random jumps occur to this
124 address, fill from 0xf0 to 0x100 */
125 .rept 4
126 KILL_INSN
127 .endr
128
129/* This address must remain fixed at 0x100 for glibc's syscalls to work */
130 .align LINUX_GATEWAY_ADDR
131linux_gateway_entry:
132 gate .+8, %r0 /* become privileged */
133 mtsp %r0,%sr4 /* get kernel space into sr4 */
134 mtsp %r0,%sr5 /* get kernel space into sr5 */
135 mtsp %r0,%sr6 /* get kernel space into sr6 */
136
137#ifdef CONFIG_64BIT
138 /* Store W bit on entry to the syscall in case it's a wide userland
139 * process. */
140 ssm PSW_SM_W, %r1
141 extrd,u %r1,PSW_W_BIT,1,%r1
142 /* sp must be aligned on 4, so deposit the W bit setting into
143 * the bottom of sp temporarily */
144 or,ev %r1,%r30,%r30
145 b,n 1f
146 /* The top halves of argument registers must be cleared on syscall
147 * entry from narrow executable.
148 */
149 depdi 0, 31, 32, %r26
150 depdi 0, 31, 32, %r25
151 depdi 0, 31, 32, %r24
152 depdi 0, 31, 32, %r23
153 depdi 0, 31, 32, %r22
154 depdi 0, 31, 32, %r21
1551:
156#endif
157
158 /* We use a rsm/ssm pair to prevent sr3 from being clobbered
159 * by external interrupts.
160 */
161 mfsp %sr7,%r1 /* save user sr7 */
162 rsm PSW_SM_I, %r0 /* disable interrupts */
163 mtsp %r1,%sr3 /* and store it in sr3 */
164
165 mfctl %cr30,%r1
166 xor %r1,%r30,%r30 /* ye olde xor trick */
167 xor %r1,%r30,%r1
168 xor %r1,%r30,%r30
169
170 LDREG TASK_STACK(%r30),%r30 /* set up kernel stack */
171 ldo FRAME_SIZE(%r30),%r30
172 /* N.B.: It is critical that we don't set sr7 to 0 until r30
173 * contains a valid kernel stack pointer. It is also
174 * critical that we don't start using the kernel stack
175 * until after sr7 has been set to 0.
176 */
177
178 mtsp %r0,%sr7 /* get kernel space into sr7 */
179 ssm PSW_SM_I, %r0 /* enable interrupts */
180 STREGM %r1,FRAME_SIZE(%r30) /* save r1 (usp) here for now */
181 mfctl %cr30,%r1 /* get task ptr in %r1 */
182
183 /* Save some registers for sigcontext and potential task
184 switch (see entry.S for the details of which ones are
185 saved/restored). TASK_PT_PSW is zeroed so we can see whether
186 a process is on a syscall or not. For an interrupt the real
187 PSW value is stored. This is needed for gdb and sys_ptrace. */
188 STREG %r0, TASK_PT_PSW(%r1)
189 STREG %r2, TASK_PT_GR2(%r1) /* preserve rp */
190 STREG %r19, TASK_PT_GR19(%r1)
191
192 LDREGM -FRAME_SIZE(%r30), %r2 /* get users sp back */
193#ifdef CONFIG_64BIT
194 extrd,u %r2,63,1,%r19 /* W hidden in bottom bit */
195#if 0
196 xor %r19,%r2,%r2 /* clear bottom bit */
197 depd,z %r19,1,1,%r19
198 std %r19,TASK_PT_PSW(%r1)
199#endif
200#endif
201 STREG %r2, TASK_PT_GR30(%r1) /* ... and save it */
202
203 STREG %r20, TASK_PT_GR20(%r1) /* Syscall number */
204 STREG %r21, TASK_PT_GR21(%r1)
205 STREG %r22, TASK_PT_GR22(%r1)
206 STREG %r23, TASK_PT_GR23(%r1) /* 4th argument */
207 STREG %r24, TASK_PT_GR24(%r1) /* 3rd argument */
208 STREG %r25, TASK_PT_GR25(%r1) /* 2nd argument */
209 STREG %r26, TASK_PT_GR26(%r1) /* 1st argument */
210 STREG %r27, TASK_PT_GR27(%r1) /* user dp */
211 STREG %r28, TASK_PT_GR28(%r1) /* return value 0 */
212 STREG %r0, TASK_PT_ORIG_R28(%r1) /* don't prohibit restarts */
213 STREG %r29, TASK_PT_GR29(%r1) /* return value 1 */
214 STREG %r31, TASK_PT_GR31(%r1) /* preserve syscall return ptr */
215
216 ldo TASK_PT_FR0(%r1), %r27 /* save fpregs from the kernel */
217 save_fp %r27 /* or potential task switch */
218
219 mfctl %cr11, %r27 /* i.e. SAR */
220 STREG %r27, TASK_PT_SAR(%r1)
221
222 loadgp
223
224#ifdef CONFIG_64BIT
225 ldo -16(%r30),%r29 /* Reference param save area */
226 copy %r19,%r2 /* W bit back to r2 */
227#else
228 /* no need to save these on stack in wide mode because the first 8
229 * args are passed in registers */
230 stw %r22, -52(%r30) /* 5th argument */
231 stw %r21, -56(%r30) /* 6th argument */
232#endif
233
234 /* Are we being ptraced? */
235 mfctl %cr30, %r1
236 LDREG TASK_TI_FLAGS(%r1),%r1
237 ldi _TIF_SYSCALL_TRACE_MASK, %r19
238 and,COND(=) %r1, %r19, %r0
239 b,n .Ltracesys
240
241 /* Note! We cannot use the syscall table that is mapped
242 nearby since the gateway page is mapped execute-only. */
243
244#ifdef CONFIG_64BIT
245 ldil L%sys_call_table, %r1
246 or,ev %r2,%r2,%r2
247 ldil L%sys_call_table64, %r1
248 ldo R%sys_call_table(%r1), %r19
249 or,ev %r2,%r2,%r2
250 ldo R%sys_call_table64(%r1), %r19
251#else
252 load32 sys_call_table, %r19
253#endif
254 comiclr,>> __NR_Linux_syscalls, %r20, %r0
255 b,n .Lsyscall_nosys
256
257 LDREGX %r20(%r19), %r19
258
259 /* If this is a sys_rt_sigreturn call, and the signal was received
260 * when not in_syscall, then we want to return via syscall_exit_rfi,
261 * not syscall_exit. Signal no. in r20, in_syscall in r25 (see
262 * trampoline code in signal.c).
263 */
264 ldi __NR_rt_sigreturn,%r2
265 comb,= %r2,%r20,.Lrt_sigreturn
266.Lin_syscall:
267 ldil L%syscall_exit,%r2
268 be 0(%sr7,%r19)
269 ldo R%syscall_exit(%r2),%r2
270.Lrt_sigreturn:
271 comib,<> 0,%r25,.Lin_syscall
272 ldil L%syscall_exit_rfi,%r2
273 be 0(%sr7,%r19)
274 ldo R%syscall_exit_rfi(%r2),%r2
275
276 /* Note! Because we are not running where we were linked, any
277 calls to functions external to this file must be indirect. To
278 be safe, we apply the opposite rule to functions within this
279 file, with local labels given to them to ensure correctness. */
280
281.Lsyscall_nosys:
282syscall_nosys:
283 ldil L%syscall_exit,%r1
284 be R%syscall_exit(%sr7,%r1)
285 ldo -ENOSYS(%r0),%r28 /* set errno */
286
287
288/* Warning! This trace code is a virtual duplicate of the code above so be
289 * sure to maintain both! */
290.Ltracesys:
291tracesys:
292 /* Need to save more registers so the debugger can see where we
293 * are. This saves only the lower 8 bits of PSW, so that the C
294 * bit is still clear on syscalls, and the D bit is set if this
295 * full register save path has been executed. We check the D
296 * bit on syscall_return_rfi to determine which registers to
297 * restore. An interrupt results in a full PSW saved with the
298 * C bit set, a non-straced syscall entry results in C and D clear
299 * in the saved PSW.
300 */
301 mfctl %cr30,%r1 /* get task ptr */
302 ssm 0,%r2
303 STREG %r2,TASK_PT_PSW(%r1) /* Lower 8 bits only!! */
304 mfsp %sr0,%r2
305 STREG %r2,TASK_PT_SR0(%r1)
306 mfsp %sr1,%r2
307 STREG %r2,TASK_PT_SR1(%r1)
308 mfsp %sr2,%r2
309 STREG %r2,TASK_PT_SR2(%r1)
310 mfsp %sr3,%r2
311 STREG %r2,TASK_PT_SR3(%r1)
312 STREG %r2,TASK_PT_SR4(%r1)
313 STREG %r2,TASK_PT_SR5(%r1)
314 STREG %r2,TASK_PT_SR6(%r1)
315 STREG %r2,TASK_PT_SR7(%r1)
316 STREG %r2,TASK_PT_IASQ0(%r1)
317 STREG %r2,TASK_PT_IASQ1(%r1)
318 LDREG TASK_PT_GR31(%r1),%r2
319 STREG %r2,TASK_PT_IAOQ0(%r1)
320 ldo 4(%r2),%r2
321 STREG %r2,TASK_PT_IAOQ1(%r1)
322 ldo TASK_REGS(%r1),%r2
323 /* reg_save %r2 */
324 STREG %r3,PT_GR3(%r2)
325 STREG %r4,PT_GR4(%r2)
326 STREG %r5,PT_GR5(%r2)
327 STREG %r6,PT_GR6(%r2)
328 STREG %r7,PT_GR7(%r2)
329 STREG %r8,PT_GR8(%r2)
330 STREG %r9,PT_GR9(%r2)
331 STREG %r10,PT_GR10(%r2)
332 STREG %r11,PT_GR11(%r2)
333 STREG %r12,PT_GR12(%r2)
334 STREG %r13,PT_GR13(%r2)
335 STREG %r14,PT_GR14(%r2)
336 STREG %r15,PT_GR15(%r2)
337 STREG %r16,PT_GR16(%r2)
338 STREG %r17,PT_GR17(%r2)
339 STREG %r18,PT_GR18(%r2)
340 /* Finished saving things for the debugger */
341
342 copy %r2,%r26
343 ldil L%do_syscall_trace_enter,%r1
344 ldil L%tracesys_next,%r2
345 be R%do_syscall_trace_enter(%sr7,%r1)
346 ldo R%tracesys_next(%r2),%r2
347
348tracesys_next:
349 /* do_syscall_trace_enter either returned the syscallno, or -1L,
350 * so we skip restoring the PT_GR20 below, since we pulled it from
351 * task->thread.regs.gr[20] above.
352 */
353 copy %ret0,%r20
354
355 mfctl %cr30,%r1 /* get task ptr */
356 LDREG TASK_PT_GR28(%r1), %r28 /* Restore return value */
357 LDREG TASK_PT_GR26(%r1), %r26 /* Restore the users args */
358 LDREG TASK_PT_GR25(%r1), %r25
359 LDREG TASK_PT_GR24(%r1), %r24
360 LDREG TASK_PT_GR23(%r1), %r23
361 LDREG TASK_PT_GR22(%r1), %r22
362 LDREG TASK_PT_GR21(%r1), %r21
363#ifdef CONFIG_64BIT
364 ldo -16(%r30),%r29 /* Reference param save area */
365#else
366 stw %r22, -52(%r30) /* 5th argument */
367 stw %r21, -56(%r30) /* 6th argument */
368#endif
369
370 cmpib,COND(=),n -1,%r20,tracesys_exit /* seccomp may have returned -1 */
371 comiclr,>> __NR_Linux_syscalls, %r20, %r0
372 b,n .Ltracesys_nosys
373
374 /* Note! We cannot use the syscall table that is mapped
375 nearby since the gateway page is mapped execute-only. */
376
377#ifdef CONFIG_64BIT
378 LDREG TASK_PT_GR30(%r1), %r19 /* get users sp back */
379 extrd,u %r19,63,1,%r2 /* W hidden in bottom bit */
380
381 ldil L%sys_call_table, %r1
382 or,ev %r2,%r2,%r2
383 ldil L%sys_call_table64, %r1
384 ldo R%sys_call_table(%r1), %r19
385 or,ev %r2,%r2,%r2
386 ldo R%sys_call_table64(%r1), %r19
387#else
388 load32 sys_call_table, %r19
389#endif
390
391 LDREGX %r20(%r19), %r19
392
393 /* If this is a sys_rt_sigreturn call, and the signal was received
394 * when not in_syscall, then we want to return via syscall_exit_rfi,
395 * not syscall_exit. Signal no. in r20, in_syscall in r25 (see
396 * trampoline code in signal.c).
397 */
398 ldi __NR_rt_sigreturn,%r2
399 comb,= %r2,%r20,.Ltrace_rt_sigreturn
400.Ltrace_in_syscall:
401 ldil L%tracesys_exit,%r2
402 be 0(%sr7,%r19)
403 ldo R%tracesys_exit(%r2),%r2
404
405.Ltracesys_nosys:
406 ldo -ENOSYS(%r0),%r28 /* set errno */
407
408 /* Do *not* call this function on the gateway page, because it
409 makes a direct call to syscall_trace. */
410
411tracesys_exit:
412 mfctl %cr30,%r1 /* get task ptr */
413#ifdef CONFIG_64BIT
414 ldo -16(%r30),%r29 /* Reference param save area */
415#endif
416 ldo TASK_REGS(%r1),%r26
417 BL do_syscall_trace_exit,%r2
418 STREG %r28,TASK_PT_GR28(%r1) /* save return value now */
419 mfctl %cr30,%r1 /* get task ptr */
420 LDREG TASK_PT_GR28(%r1), %r28 /* Restore return val. */
421
422 ldil L%syscall_exit,%r1
423 be,n R%syscall_exit(%sr7,%r1)
424
425.Ltrace_rt_sigreturn:
426 comib,<> 0,%r25,.Ltrace_in_syscall
427 ldil L%tracesys_sigexit,%r2
428 be 0(%sr7,%r19)
429 ldo R%tracesys_sigexit(%r2),%r2
430
431tracesys_sigexit:
432 mfctl %cr30,%r1 /* get task ptr */
433#ifdef CONFIG_64BIT
434 ldo -16(%r30),%r29 /* Reference param save area */
435#endif
436 BL do_syscall_trace_exit,%r2
437 ldo TASK_REGS(%r1),%r26
438
439 ldil L%syscall_exit_rfi,%r1
440 be,n R%syscall_exit_rfi(%sr7,%r1)
441
442
443 /*********************************************************
444 32/64-bit Light-Weight-Syscall ABI
445
446 * - Indicates a hint for userspace inline asm
447 implementations.
448
449 Syscall number (caller-saves)
450 - %r20
451 * In asm clobber.
452
453 Argument registers (caller-saves)
454 - %r26, %r25, %r24, %r23, %r22
455 * In asm input.
456
457 Return registers (caller-saves)
458 - %r28 (return), %r21 (errno)
459 * In asm output.
460
461 Caller-saves registers
462 - %r1, %r27, %r29
463 - %r2 (return pointer)
464 - %r31 (ble link register)
465 * In asm clobber.
466
467 Callee-saves registers
468 - %r3-%r18
469 - %r30 (stack pointer)
470 * Not in asm clobber.
471
472 If userspace is 32-bit:
473 Callee-saves registers
474 - %r19 (32-bit PIC register)
475
476 Differences from 32-bit calling convention:
477 - Syscall number in %r20
478 - Additional argument register %r22 (arg4)
479 - Callee-saves %r19.
480
481 If userspace is 64-bit:
482 Callee-saves registers
483 - %r27 (64-bit PIC register)
484
485 Differences from 64-bit calling convention:
486 - Syscall number in %r20
487 - Additional argument register %r22 (arg4)
488 - Callee-saves %r27.
489
490 Error codes returned by entry path:
491
492 ENOSYS - r20 was an invalid LWS number.
493
494 *********************************************************/
495lws_start:
496
497#ifdef CONFIG_64BIT
498 ssm PSW_SM_W, %r1
499 extrd,u %r1,PSW_W_BIT,1,%r1
500 /* sp must be aligned on 4, so deposit the W bit setting into
501 * the bottom of sp temporarily */
502 or,od %r1,%r30,%r30
503
504 /* Clip LWS number to a 32-bit value for 32-bit processes */
505 depdi 0, 31, 32, %r20
506#endif
507
508 /* Is the lws entry number valid? */
509 comiclr,>> __NR_lws_entries, %r20, %r0
510 b,n lws_exit_nosys
511
512 /* Load table start */
513 ldil L%lws_table, %r1
514 ldo R%lws_table(%r1), %r28 /* Scratch use of r28 */
515 LDREGX %r20(%sr2,r28), %r21 /* Scratch use of r21 */
516
517 /* Jump to lws, lws table pointers already relocated */
518 be,n 0(%sr2,%r21)
519
520lws_exit_noerror:
521 lws_pagefault_enable %r1,%r21
522 ldi __ARCH_SPIN_LOCK_UNLOCKED_VAL, %r21
523 stw,ma %r21, 0(%sr2,%r20)
524 ssm PSW_SM_I, %r0
525 b lws_exit
526 copy %r0, %r21
527
528lws_wouldblock:
529 ssm PSW_SM_I, %r0
530 ldo 2(%r0), %r28
531 b lws_exit
532 ldo -EAGAIN(%r0), %r21
533
534lws_pagefault:
535 lws_pagefault_enable %r1,%r21
536 ldi __ARCH_SPIN_LOCK_UNLOCKED_VAL, %r21
537 stw,ma %r21, 0(%sr2,%r20)
538 ssm PSW_SM_I, %r0
539 ldo 3(%r0),%r28
540 b lws_exit
541 ldo -EAGAIN(%r0),%r21
542
543lws_fault:
544 ldo 1(%r0),%r28
545 b lws_exit
546 ldo -EFAULT(%r0),%r21
547
548lws_exit_nosys:
549 ldo -ENOSYS(%r0),%r21
550 /* Fall through: Return to userspace */
551
552lws_exit:
553#ifdef CONFIG_64BIT
554 /* decide whether to reset the wide mode bit
555 *
556 * For a syscall, the W bit is stored in the lowest bit
557 * of sp. Extract it and reset W if it is zero */
558 extrd,u,*<> %r30,63,1,%r1
559 rsm PSW_SM_W, %r0
560 /* now reset the lowest bit of sp if it was set */
561 xor %r30,%r1,%r30
562#endif
563 be,n 0(%sr7, %r31)
564
565
566
567 /***************************************************
568 Implementing 32bit CAS as an atomic operation:
569
570 %r26 - Address to examine
571 %r25 - Old value to check (old)
572 %r24 - New value to set (new)
573 %r28 - Return prev through this register.
574 %r21 - Kernel error code
575
576 %r21 returns the following error codes:
577 EAGAIN - CAS is busy, ldcw failed, try again.
578 EFAULT - Read or write failed.
579
580 If EAGAIN is returned, %r28 indicates the busy reason:
581 r28 == 1 - CAS is busy. lock contended.
582 r28 == 2 - CAS is busy. ldcw failed.
583 r28 == 3 - CAS is busy. page fault.
584
585 Scratch: r20, r28, r1
586
587 ****************************************************/
588
589 /* ELF64 Process entry path */
590lws_compare_and_swap64:
591#ifdef CONFIG_64BIT
592 b,n lws_compare_and_swap
593#else
594 /* If we are not a 64-bit kernel, then we don't
595 * have 64-bit input registers, and calling
596 * the 64-bit LWS CAS returns ENOSYS.
597 */
598 b,n lws_exit_nosys
599#endif
600
601 /* ELF32/ELF64 Process entry path */
602lws_compare_and_swap32:
603#ifdef CONFIG_64BIT
604 /* Wide mode user process? */
605 bb,<,n %sp, 31, lws_compare_and_swap
606
607 /* Clip all the input registers for 32-bit processes */
608 depdi 0, 31, 32, %r26
609 depdi 0, 31, 32, %r25
610 depdi 0, 31, 32, %r24
611#endif
612
613lws_compare_and_swap:
614 /* Trigger memory reference interruptions without writing to memory */
6151: ldw 0(%r26), %r28
6162: stbys,e %r0, 0(%r26)
617
618 /* Calculate 8-bit hash index from virtual address */
619 extru_safe %r26, 27, 8, %r20
620
621 /* Load start of lock table */
622 ldil L%lws_lock_start, %r28
623 ldo R%lws_lock_start(%r28), %r28
624
625 /* Find lock to use, the hash index is one of 0 to
626 255, multiplied by 16 (keep it 16-byte aligned)
627 and add to the lock table offset. */
628 shlw %r20, 4, %r20
629 add %r20, %r28, %r20
630
631 rsm PSW_SM_I, %r0 /* Disable interrupts */
632
633 /* Try to acquire the lock */
634 LDCW 0(%sr2,%r20), %r28
635 spinlock_check %r28, %r21
636 comclr,<> %r0, %r28, %r0
637 b,n lws_wouldblock
638
639 /* Disable page faults to prevent sleeping in critical region */
640 lws_pagefault_disable %r21,%r28
641
642 /*
643 prev = *addr;
644 if ( prev == old )
645 *addr = new;
646 return prev;
647 */
648
649 /* NOTES:
650 This all works because intr_do_signal
651 and schedule both check the return iasq
652 and see that we are on the kernel page
653 so this process is never scheduled off
654 or is ever sent any signal of any sort,
655 thus it is wholly atomic from usrspace's
656 perspective
657 */
658 /* The load and store could fail */
6593: ldw 0(%r26), %r28
660 sub,<> %r28, %r25, %r0
6614: stw %r24, 0(%r26)
662 b,n lws_exit_noerror
663
664 /* A fault occurred on load or stbys,e store */
6655: b,n lws_fault
666 ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 5b-linux_gateway_page)
667 ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 5b-linux_gateway_page)
668
669 /* A page fault occurred in critical region */
6706: b,n lws_pagefault
671 ASM_EXCEPTIONTABLE_ENTRY(3b-linux_gateway_page, 6b-linux_gateway_page)
672 ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 6b-linux_gateway_page)
673
674
675 /***************************************************
676 New CAS implementation which uses pointers and variable size
677 information. The value pointed by old and new MUST NOT change
678 while performing CAS. The lock only protects the value at %r26.
679
680 %r26 - Address to examine
681 %r25 - Pointer to the value to check (old)
682 %r24 - Pointer to the value to set (new)
683 %r23 - Size of the variable (0/1/2/3 for 8/16/32/64 bit)
684 %r28 - Return non-zero on failure
685 %r21 - Kernel error code
686
687 %r21 returns the following error codes:
688 EAGAIN - CAS is busy, ldcw failed, try again.
689 EFAULT - Read or write failed.
690
691 If EAGAIN is returned, %r28 indicates the busy reason:
692 r28 == 1 - CAS is busy. lock contended.
693 r28 == 2 - CAS is busy. ldcw failed.
694 r28 == 3 - CAS is busy. page fault.
695
696 Scratch: r20, r22, r28, r29, r1, fr4 (32bit for 64bit CAS only)
697
698 ****************************************************/
699
700lws_compare_and_swap_2:
701#ifdef CONFIG_64BIT
702 /* Wide mode user process? */
703 bb,<,n %sp, 31, cas2_begin
704
705 /* Clip the input registers for 32-bit processes. We don't
706 need to clip %r23 as we only use it for word operations */
707 depdi 0, 31, 32, %r26
708 depdi 0, 31, 32, %r25
709 depdi 0, 31, 32, %r24
710#endif
711
712cas2_begin:
713 /* Check the validity of the size pointer */
714 subi,>>= 3, %r23, %r0
715 b,n lws_exit_nosys
716
717 /* Jump to the functions which will load the old and new values into
718 registers depending on the their size */
719 shlw %r23, 2, %r29
720 blr %r29, %r0
721 nop
722
723 /* 8-bit load */
7241: ldb 0(%r25), %r25
725 b cas2_lock_start
7262: ldb 0(%r24), %r24
727 nop
728 nop
729 nop
730 nop
731 nop
732
733 /* 16-bit load */
7343: ldh 0(%r25), %r25
735 b cas2_lock_start
7364: ldh 0(%r24), %r24
737 nop
738 nop
739 nop
740 nop
741 nop
742
743 /* 32-bit load */
7445: ldw 0(%r25), %r25
745 b cas2_lock_start
7466: ldw 0(%r24), %r24
747 nop
748 nop
749 nop
750 nop
751 nop
752
753 /* 64-bit load */
754#ifdef CONFIG_64BIT
7557: ldd 0(%r25), %r25
7568: ldd 0(%r24), %r24
757#else
758 /* Load old value into r22/r23 - high/low */
7597: ldw 0(%r25), %r22
7608: ldw 4(%r25), %r23
761 /* Load new value into fr4 for atomic store later */
7629: flddx 0(%r24), %fr4
763#endif
764
765cas2_lock_start:
766 /* Trigger memory reference interruptions without writing to memory */
767 copy %r26, %r28
768 depi_safe 0, 31, 2, %r28
76910: ldw 0(%r28), %r1
77011: stbys,e %r0, 0(%r28)
771
772 /* Calculate 8-bit hash index from virtual address */
773 extru_safe %r26, 27, 8, %r20
774
775 /* Load start of lock table */
776 ldil L%lws_lock_start, %r28
777 ldo R%lws_lock_start(%r28), %r28
778
779 /* Find lock to use, the hash index is one of 0 to
780 255, multiplied by 16 (keep it 16-byte aligned)
781 and add to the lock table offset. */
782 shlw %r20, 4, %r20
783 add %r20, %r28, %r20
784
785 rsm PSW_SM_I, %r0 /* Disable interrupts */
786
787 /* Try to acquire the lock */
788 LDCW 0(%sr2,%r20), %r28
789 spinlock_check %r28, %r21
790 comclr,<> %r0, %r28, %r0
791 b,n lws_wouldblock
792
793 /* Disable page faults to prevent sleeping in critical region */
794 lws_pagefault_disable %r21,%r28
795
796 /*
797 prev = *addr;
798 if ( prev == old )
799 *addr = new;
800 return prev;
801 */
802
803 /* NOTES:
804 This all works because intr_do_signal
805 and schedule both check the return iasq
806 and see that we are on the kernel page
807 so this process is never scheduled off
808 or is ever sent any signal of any sort,
809 thus it is wholly atomic from usrspace's
810 perspective
811 */
812
813 /* Jump to the correct function */
814 blr %r29, %r0
815 /* Set %r28 as non-zero for now */
816 ldo 1(%r0),%r28
817
818 /* 8-bit CAS */
81912: ldb 0(%r26), %r29
820 sub,= %r29, %r25, %r0
821 b,n lws_exit_noerror
82213: stb %r24, 0(%r26)
823 b lws_exit_noerror
824 copy %r0, %r28
825 nop
826 nop
827
828 /* 16-bit CAS */
82914: ldh 0(%r26), %r29
830 sub,= %r29, %r25, %r0
831 b,n lws_exit_noerror
83215: sth %r24, 0(%r26)
833 b lws_exit_noerror
834 copy %r0, %r28
835 nop
836 nop
837
838 /* 32-bit CAS */
83916: ldw 0(%r26), %r29
840 sub,= %r29, %r25, %r0
841 b,n lws_exit_noerror
84217: stw %r24, 0(%r26)
843 b lws_exit_noerror
844 copy %r0, %r28
845 nop
846 nop
847
848 /* 64-bit CAS */
849#ifdef CONFIG_64BIT
85018: ldd 0(%r26), %r29
851 sub,*= %r29, %r25, %r0
852 b,n lws_exit_noerror
85319: std %r24, 0(%r26)
854 copy %r0, %r28
855#else
856 /* Compare first word */
85718: ldw 0(%r26), %r29
858 sub,= %r29, %r22, %r0
859 b,n lws_exit_noerror
860 /* Compare second word */
86119: ldw 4(%r26), %r29
862 sub,= %r29, %r23, %r0
863 b,n lws_exit_noerror
864 /* Perform the store */
86520: fstdx %fr4, 0(%r26)
866 copy %r0, %r28
867#endif
868 b lws_exit_noerror
869 copy %r0, %r28
870
871 /* A fault occurred on load or stbys,e store */
87230: b,n lws_fault
873 ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 30b-linux_gateway_page)
874 ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 30b-linux_gateway_page)
875 ASM_EXCEPTIONTABLE_ENTRY(3b-linux_gateway_page, 30b-linux_gateway_page)
876 ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 30b-linux_gateway_page)
877 ASM_EXCEPTIONTABLE_ENTRY(5b-linux_gateway_page, 30b-linux_gateway_page)
878 ASM_EXCEPTIONTABLE_ENTRY(6b-linux_gateway_page, 30b-linux_gateway_page)
879 ASM_EXCEPTIONTABLE_ENTRY(7b-linux_gateway_page, 30b-linux_gateway_page)
880 ASM_EXCEPTIONTABLE_ENTRY(8b-linux_gateway_page, 30b-linux_gateway_page)
881#ifndef CONFIG_64BIT
882 ASM_EXCEPTIONTABLE_ENTRY(9b-linux_gateway_page, 30b-linux_gateway_page)
883#endif
884
885 ASM_EXCEPTIONTABLE_ENTRY(10b-linux_gateway_page, 30b-linux_gateway_page)
886 ASM_EXCEPTIONTABLE_ENTRY(11b-linux_gateway_page, 30b-linux_gateway_page)
887
888 /* A page fault occurred in critical region */
88931: b,n lws_pagefault
890 ASM_EXCEPTIONTABLE_ENTRY(12b-linux_gateway_page, 31b-linux_gateway_page)
891 ASM_EXCEPTIONTABLE_ENTRY(13b-linux_gateway_page, 31b-linux_gateway_page)
892 ASM_EXCEPTIONTABLE_ENTRY(14b-linux_gateway_page, 31b-linux_gateway_page)
893 ASM_EXCEPTIONTABLE_ENTRY(15b-linux_gateway_page, 31b-linux_gateway_page)
894 ASM_EXCEPTIONTABLE_ENTRY(16b-linux_gateway_page, 31b-linux_gateway_page)
895 ASM_EXCEPTIONTABLE_ENTRY(17b-linux_gateway_page, 31b-linux_gateway_page)
896 ASM_EXCEPTIONTABLE_ENTRY(18b-linux_gateway_page, 31b-linux_gateway_page)
897 ASM_EXCEPTIONTABLE_ENTRY(19b-linux_gateway_page, 31b-linux_gateway_page)
898#ifndef CONFIG_64BIT
899 ASM_EXCEPTIONTABLE_ENTRY(20b-linux_gateway_page, 31b-linux_gateway_page)
900#endif
901
902
903 /***************************************************
904 LWS atomic exchange.
905
906 %r26 - Exchange address
907 %r25 - Size of the variable (0/1/2/3 for 8/16/32/64 bit)
908 %r24 - Address of new value
909 %r23 - Address of old value
910 %r28 - Return non-zero on failure
911 %r21 - Kernel error code
912
913 %r21 returns the following error codes:
914 EAGAIN - CAS is busy, ldcw failed, try again.
915 EFAULT - Read or write failed.
916
917 If EAGAIN is returned, %r28 indicates the busy reason:
918 r28 == 1 - CAS is busy. lock contended.
919 r28 == 2 - CAS is busy. ldcw failed.
920 r28 == 3 - CAS is busy. page fault.
921
922 Scratch: r20, r1
923
924 ****************************************************/
925
926lws_atomic_xchg:
927#ifdef CONFIG_64BIT
928 /* Wide mode user process? */
929 bb,<,n %sp, 31, atomic_xchg_begin
930
931 /* Clip the input registers for 32-bit processes. We don't
932 need to clip %r23 as we only use it for word operations */
933 depdi 0, 31, 32, %r26
934 depdi 0, 31, 32, %r25
935 depdi 0, 31, 32, %r24
936 depdi 0, 31, 32, %r23
937#endif
938
939atomic_xchg_begin:
940 /* Check the validity of the size pointer */
941 subi,>>= 3, %r25, %r0
942 b,n lws_exit_nosys
943
944 /* Jump to the functions which will load the old and new values into
945 registers depending on the their size */
946 shlw %r25, 2, %r1
947 blr %r1, %r0
948 nop
949
950 /* Perform exception checks */
951
952 /* 8-bit exchange */
9531: ldb 0(%r24), %r20
954 copy %r23, %r20
955 depi_safe 0, 31, 2, %r20
956 b atomic_xchg_start
9572: stbys,e %r0, 0(%r20)
958 nop
959 nop
960 nop
961
962 /* 16-bit exchange */
9633: ldh 0(%r24), %r20
964 copy %r23, %r20
965 depi_safe 0, 31, 2, %r20
966 b atomic_xchg_start
9674: stbys,e %r0, 0(%r20)
968 nop
969 nop
970 nop
971
972 /* 32-bit exchange */
9735: ldw 0(%r24), %r20
974 b atomic_xchg_start
9756: stbys,e %r0, 0(%r23)
976 nop
977 nop
978 nop
979 nop
980 nop
981
982 /* 64-bit exchange */
983#ifdef CONFIG_64BIT
9847: ldd 0(%r24), %r20
9858: stdby,e %r0, 0(%r23)
986#else
9877: ldw 0(%r24), %r20
9888: ldw 4(%r24), %r20
989 copy %r23, %r20
990 depi_safe 0, 31, 2, %r20
9919: stbys,e %r0, 0(%r20)
99210: stbys,e %r0, 4(%r20)
993#endif
994
995atomic_xchg_start:
996 /* Trigger memory reference interruptions without writing to memory */
997 copy %r26, %r28
998 depi_safe 0, 31, 2, %r28
99911: ldw 0(%r28), %r1
100012: stbys,e %r0, 0(%r28)
1001
1002 /* Calculate 8-bit hash index from virtual address */
1003 extru_safe %r26, 27, 8, %r20
1004
1005 /* Load start of lock table */
1006 ldil L%lws_lock_start, %r28
1007 ldo R%lws_lock_start(%r28), %r28
1008
1009 /* Find lock to use, the hash index is one of 0 to
1010 255, multiplied by 16 (keep it 16-byte aligned)
1011 and add to the lock table offset. */
1012 shlw %r20, 4, %r20
1013 add %r20, %r28, %r20
1014
1015 rsm PSW_SM_I, %r0 /* Disable interrupts */
1016
1017 /* Try to acquire the lock */
1018 LDCW 0(%sr2,%r20), %r28
1019 spinlock_check %r28, %r21
1020 comclr,<> %r0, %r28, %r0
1021 b,n lws_wouldblock
1022
1023 /* Disable page faults to prevent sleeping in critical region */
1024 lws_pagefault_disable %r21,%r28
1025
1026 /* NOTES:
1027 This all works because intr_do_signal
1028 and schedule both check the return iasq
1029 and see that we are on the kernel page
1030 so this process is never scheduled off
1031 or is ever sent any signal of any sort,
1032 thus it is wholly atomic from userspace's
1033 perspective
1034 */
1035
1036 /* Jump to the correct function */
1037 blr %r1, %r0
1038 /* Set %r28 as non-zero for now */
1039 ldo 1(%r0),%r28
1040
1041 /* 8-bit exchange */
104214: ldb 0(%r26), %r1
104315: stb %r1, 0(%r23)
104415: ldb 0(%r24), %r1
104517: stb %r1, 0(%r26)
1046 b lws_exit_noerror
1047 copy %r0, %r28
1048 nop
1049 nop
1050
1051 /* 16-bit exchange */
105218: ldh 0(%r26), %r1
105319: sth %r1, 0(%r23)
105420: ldh 0(%r24), %r1
105521: sth %r1, 0(%r26)
1056 b lws_exit_noerror
1057 copy %r0, %r28
1058 nop
1059 nop
1060
1061 /* 32-bit exchange */
106222: ldw 0(%r26), %r1
106323: stw %r1, 0(%r23)
106424: ldw 0(%r24), %r1
106525: stw %r1, 0(%r26)
1066 b lws_exit_noerror
1067 copy %r0, %r28
1068 nop
1069 nop
1070
1071 /* 64-bit exchange */
1072#ifdef CONFIG_64BIT
107326: ldd 0(%r26), %r1
107427: std %r1, 0(%r23)
107528: ldd 0(%r24), %r1
107629: std %r1, 0(%r26)
1077#else
107826: flddx 0(%r26), %fr4
107927: fstdx %fr4, 0(%r23)
108028: flddx 0(%r24), %fr4
108129: fstdx %fr4, 0(%r26)
1082#endif
1083 b lws_exit_noerror
1084 copy %r0, %r28
1085
1086 /* A fault occurred on load or stbys,e store */
108730: b,n lws_fault
1088 ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 30b-linux_gateway_page)
1089 ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 30b-linux_gateway_page)
1090 ASM_EXCEPTIONTABLE_ENTRY(3b-linux_gateway_page, 30b-linux_gateway_page)
1091 ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 30b-linux_gateway_page)
1092 ASM_EXCEPTIONTABLE_ENTRY(5b-linux_gateway_page, 30b-linux_gateway_page)
1093 ASM_EXCEPTIONTABLE_ENTRY(6b-linux_gateway_page, 30b-linux_gateway_page)
1094 ASM_EXCEPTIONTABLE_ENTRY(7b-linux_gateway_page, 30b-linux_gateway_page)
1095 ASM_EXCEPTIONTABLE_ENTRY(8b-linux_gateway_page, 30b-linux_gateway_page)
1096#ifndef CONFIG_64BIT
1097 ASM_EXCEPTIONTABLE_ENTRY(9b-linux_gateway_page, 30b-linux_gateway_page)
1098 ASM_EXCEPTIONTABLE_ENTRY(10b-linux_gateway_page, 30b-linux_gateway_page)
1099#endif
1100
1101 ASM_EXCEPTIONTABLE_ENTRY(11b-linux_gateway_page, 30b-linux_gateway_page)
1102 ASM_EXCEPTIONTABLE_ENTRY(12b-linux_gateway_page, 30b-linux_gateway_page)
1103
1104 /* A page fault occurred in critical region */
110531: b,n lws_pagefault
1106 ASM_EXCEPTIONTABLE_ENTRY(14b-linux_gateway_page, 31b-linux_gateway_page)
1107 ASM_EXCEPTIONTABLE_ENTRY(15b-linux_gateway_page, 31b-linux_gateway_page)
1108 ASM_EXCEPTIONTABLE_ENTRY(16b-linux_gateway_page, 31b-linux_gateway_page)
1109 ASM_EXCEPTIONTABLE_ENTRY(17b-linux_gateway_page, 31b-linux_gateway_page)
1110 ASM_EXCEPTIONTABLE_ENTRY(18b-linux_gateway_page, 31b-linux_gateway_page)
1111 ASM_EXCEPTIONTABLE_ENTRY(19b-linux_gateway_page, 31b-linux_gateway_page)
1112 ASM_EXCEPTIONTABLE_ENTRY(20b-linux_gateway_page, 31b-linux_gateway_page)
1113 ASM_EXCEPTIONTABLE_ENTRY(21b-linux_gateway_page, 31b-linux_gateway_page)
1114 ASM_EXCEPTIONTABLE_ENTRY(22b-linux_gateway_page, 31b-linux_gateway_page)
1115 ASM_EXCEPTIONTABLE_ENTRY(23b-linux_gateway_page, 31b-linux_gateway_page)
1116 ASM_EXCEPTIONTABLE_ENTRY(24b-linux_gateway_page, 31b-linux_gateway_page)
1117 ASM_EXCEPTIONTABLE_ENTRY(25b-linux_gateway_page, 31b-linux_gateway_page)
1118 ASM_EXCEPTIONTABLE_ENTRY(26b-linux_gateway_page, 31b-linux_gateway_page)
1119 ASM_EXCEPTIONTABLE_ENTRY(27b-linux_gateway_page, 31b-linux_gateway_page)
1120 ASM_EXCEPTIONTABLE_ENTRY(28b-linux_gateway_page, 31b-linux_gateway_page)
1121 ASM_EXCEPTIONTABLE_ENTRY(29b-linux_gateway_page, 31b-linux_gateway_page)
1122
1123 /***************************************************
1124 LWS atomic store.
1125
1126 %r26 - Address to store
1127 %r25 - Size of the variable (0/1/2/3 for 8/16/32/64 bit)
1128 %r24 - Address of value to store
1129 %r28 - Return non-zero on failure
1130 %r21 - Kernel error code
1131
1132 %r21 returns the following error codes:
1133 EAGAIN - CAS is busy, ldcw failed, try again.
1134 EFAULT - Read or write failed.
1135
1136 If EAGAIN is returned, %r28 indicates the busy reason:
1137 r28 == 1 - CAS is busy. lock contended.
1138 r28 == 2 - CAS is busy. ldcw failed.
1139 r28 == 3 - CAS is busy. page fault.
1140
1141 Scratch: r20, r1
1142
1143 ****************************************************/
1144
1145lws_atomic_store:
1146#ifdef CONFIG_64BIT
1147 /* Wide mode user process? */
1148 bb,<,n %sp, 31, atomic_store_begin
1149
1150 /* Clip the input registers for 32-bit processes. We don't
1151 need to clip %r23 as we only use it for word operations */
1152 depdi 0, 31, 32, %r26
1153 depdi 0, 31, 32, %r25
1154 depdi 0, 31, 32, %r24
1155#endif
1156
1157atomic_store_begin:
1158 /* Check the validity of the size pointer */
1159 subi,>>= 3, %r25, %r0
1160 b,n lws_exit_nosys
1161
1162 shlw %r25, 1, %r1
1163 blr %r1, %r0
1164 nop
1165
1166 /* Perform exception checks */
1167
1168 /* 8-bit store */
11691: ldb 0(%r24), %r20
1170 b,n atomic_store_start
1171 nop
1172 nop
1173
1174 /* 16-bit store */
11752: ldh 0(%r24), %r20
1176 b,n atomic_store_start
1177 nop
1178 nop
1179
1180 /* 32-bit store */
11813: ldw 0(%r24), %r20
1182 b,n atomic_store_start
1183 nop
1184 nop
1185
1186 /* 64-bit store */
1187#ifdef CONFIG_64BIT
11884: ldd 0(%r24), %r20
1189#else
11904: ldw 0(%r24), %r20
11915: ldw 4(%r24), %r20
1192#endif
1193
1194atomic_store_start:
1195 /* Trigger memory reference interruptions without writing to memory */
1196 copy %r26, %r28
1197 depi_safe 0, 31, 2, %r28
11986: ldw 0(%r28), %r1
11997: stbys,e %r0, 0(%r28)
1200
1201 /* Calculate 8-bit hash index from virtual address */
1202 extru_safe %r26, 27, 8, %r20
1203
1204 /* Load start of lock table */
1205 ldil L%lws_lock_start, %r28
1206 ldo R%lws_lock_start(%r28), %r28
1207
1208 /* Find lock to use, the hash index is one of 0 to
1209 255, multiplied by 16 (keep it 16-byte aligned)
1210 and add to the lock table offset. */
1211 shlw %r20, 4, %r20
1212 add %r20, %r28, %r20
1213
1214 rsm PSW_SM_I, %r0 /* Disable interrupts */
1215
1216 /* Try to acquire the lock */
1217 LDCW 0(%sr2,%r20), %r28
1218 spinlock_check %r28, %r21
1219 comclr,<> %r0, %r28, %r0
1220 b,n lws_wouldblock
1221
1222 /* Disable page faults to prevent sleeping in critical region */
1223 lws_pagefault_disable %r21,%r28
1224
1225 /* NOTES:
1226 This all works because intr_do_signal
1227 and schedule both check the return iasq
1228 and see that we are on the kernel page
1229 so this process is never scheduled off
1230 or is ever sent any signal of any sort,
1231 thus it is wholly atomic from userspace's
1232 perspective
1233 */
1234
1235 /* Jump to the correct function */
1236 blr %r1, %r0
1237 /* Set %r28 as non-zero for now */
1238 ldo 1(%r0),%r28
1239
1240 /* 8-bit store */
12419: ldb 0(%r24), %r1
124210: stb %r1, 0(%r26)
1243 b lws_exit_noerror
1244 copy %r0, %r28
1245
1246 /* 16-bit store */
124711: ldh 0(%r24), %r1
124812: sth %r1, 0(%r26)
1249 b lws_exit_noerror
1250 copy %r0, %r28
1251
1252 /* 32-bit store */
125313: ldw 0(%r24), %r1
125414: stw %r1, 0(%r26)
1255 b lws_exit_noerror
1256 copy %r0, %r28
1257
1258 /* 64-bit store */
1259#ifdef CONFIG_64BIT
126015: ldd 0(%r24), %r1
126116: std %r1, 0(%r26)
1262#else
126315: flddx 0(%r24), %fr4
126416: fstdx %fr4, 0(%r26)
1265#endif
1266 b lws_exit_noerror
1267 copy %r0, %r28
1268
1269 /* A fault occurred on load or stbys,e store */
127030: b,n lws_fault
1271 ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 30b-linux_gateway_page)
1272 ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 30b-linux_gateway_page)
1273 ASM_EXCEPTIONTABLE_ENTRY(3b-linux_gateway_page, 30b-linux_gateway_page)
1274 ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 30b-linux_gateway_page)
1275#ifndef CONFIG_64BIT
1276 ASM_EXCEPTIONTABLE_ENTRY(5b-linux_gateway_page, 30b-linux_gateway_page)
1277#endif
1278
1279 ASM_EXCEPTIONTABLE_ENTRY(6b-linux_gateway_page, 30b-linux_gateway_page)
1280 ASM_EXCEPTIONTABLE_ENTRY(7b-linux_gateway_page, 30b-linux_gateway_page)
1281
1282 /* A page fault occurred in critical region */
128331: b,n lws_pagefault
1284 ASM_EXCEPTIONTABLE_ENTRY(9b-linux_gateway_page, 31b-linux_gateway_page)
1285 ASM_EXCEPTIONTABLE_ENTRY(10b-linux_gateway_page, 31b-linux_gateway_page)
1286 ASM_EXCEPTIONTABLE_ENTRY(11b-linux_gateway_page, 31b-linux_gateway_page)
1287 ASM_EXCEPTIONTABLE_ENTRY(12b-linux_gateway_page, 31b-linux_gateway_page)
1288 ASM_EXCEPTIONTABLE_ENTRY(13b-linux_gateway_page, 31b-linux_gateway_page)
1289 ASM_EXCEPTIONTABLE_ENTRY(14b-linux_gateway_page, 31b-linux_gateway_page)
1290 ASM_EXCEPTIONTABLE_ENTRY(15b-linux_gateway_page, 31b-linux_gateway_page)
1291 ASM_EXCEPTIONTABLE_ENTRY(16b-linux_gateway_page, 31b-linux_gateway_page)
1292
1293 /* Make sure nothing else is placed on this page */
1294 .align PAGE_SIZE
1295END(linux_gateway_page)
1296ENTRY(end_linux_gateway_page)
1297
1298 /* Relocate symbols assuming linux_gateway_page is mapped
1299 to virtual address 0x0 */
1300
1301#define LWS_ENTRY(_name_) ASM_ULONG_INSN (lws_##_name_ - linux_gateway_page)
1302
1303 .section .rodata,"a"
1304
1305 .align 8
1306 /* Light-weight-syscall table */
1307 /* Start of lws table. */
1308ENTRY(lws_table)
1309 LWS_ENTRY(compare_and_swap32) /* 0 - ELF32 Atomic 32bit CAS */
1310 LWS_ENTRY(compare_and_swap64) /* 1 - ELF64 Atomic 32bit CAS */
1311 LWS_ENTRY(compare_and_swap_2) /* 2 - Atomic 64bit CAS */
1312 LWS_ENTRY(atomic_xchg) /* 3 - Atomic Exchange */
1313 LWS_ENTRY(atomic_store) /* 4 - Atomic Store */
1314END(lws_table)
1315 /* End of lws table */
1316
1317#ifdef CONFIG_64BIT
1318#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat)
1319#else
1320#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native)
1321#endif
1322#define __SYSCALL(nr, entry) ASM_ULONG_INSN entry
1323 .align 8
1324ENTRY(sys_call_table)
1325 .export sys_call_table,data
1326#include <asm/syscall_table_32.h> /* 32-bit syscalls */
1327END(sys_call_table)
1328
1329#ifdef CONFIG_64BIT
1330#undef __SYSCALL_WITH_COMPAT
1331#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native)
1332 .align 8
1333ENTRY(sys_call_table64)
1334#include <asm/syscall_table_64.h> /* 64-bit syscalls */
1335END(sys_call_table64)
1336#endif
1337
1338 /*
1339 All light-weight-syscall atomic operations
1340 will use this set of locks
1341
1342 NOTE: The lws_lock_start symbol must be
1343 at least 16-byte aligned for safe use
1344 with ldcw.
1345 */
1346 .section .data
1347 .align L1_CACHE_BYTES
1348ENTRY(lws_lock_start)
1349 /* lws locks */
1350 .rept 256
1351 /* Keep locks aligned at 16-bytes */
1352 .word __ARCH_SPIN_LOCK_UNLOCKED_VAL
1353 .word 0
1354 .word 0
1355 .word 0
1356 .endr
1357END(lws_lock_start)
1358 .previous
1359
1360.end