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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
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 .macro lws_pagefault_disable reg1,reg2
54 mfctl %cr30, \reg2
55 ldo TASK_PAGEFAULT_DISABLED(\reg2), \reg2
56 ldw 0(%sr2,\reg2), \reg1
57 ldo 1(\reg1), \reg1
58 stw \reg1, 0(%sr2,\reg2)
59 .endm
60
61 .macro lws_pagefault_enable reg1,reg2
62 mfctl %cr30, \reg2
63 ldo TASK_PAGEFAULT_DISABLED(\reg2), \reg2
64 ldw 0(%sr2,\reg2), \reg1
65 ldo -1(\reg1), \reg1
66 stw \reg1, 0(%sr2,\reg2)
67 .endm
68
69 .text
70
71 .import syscall_exit,code
72 .import syscall_exit_rfi,code
73
74 /* Linux gateway page is aliased to virtual page 0 in the kernel
75 * address space. Since it is a gateway page it cannot be
76 * dereferenced, so null pointers will still fault. We start
77 * the actual entry point at 0x100. We put break instructions
78 * at the beginning of the page to trap null indirect function
79 * pointers.
80 */
81
82 .align PAGE_SIZE
83ENTRY(linux_gateway_page)
84
85 /* ADDRESS 0x00 to 0xb0 = 176 bytes / 4 bytes per insn = 44 insns */
86 .rept 44
87 KILL_INSN
88 .endr
89
90 /* ADDRESS 0xb0 to 0xb8, lws uses two insns for entry */
91 /* Light-weight-syscall entry must always be located at 0xb0 */
92 /* WARNING: Keep this number updated with table size changes */
93#define __NR_lws_entries (5)
94
95lws_entry:
96 gate lws_start, %r0 /* increase privilege */
97 depi PRIV_USER, 31, 2, %r31 /* Ensure we return into user mode. */
98
99 /* Fill from 0xb8 to 0xe0 */
100 .rept 10
101 KILL_INSN
102 .endr
103
104 /* This function MUST be located at 0xe0 for glibc's threading
105 mechanism to work. DO NOT MOVE THIS CODE EVER! */
106set_thread_pointer:
107 gate .+8, %r0 /* increase privilege */
108 depi PRIV_USER, 31, 2, %r31 /* Ensure we return into user mode. */
109 be 0(%sr7,%r31) /* return to user space */
110 mtctl %r26, %cr27 /* move arg0 to the control register */
111
112 /* Increase the chance of trapping if random jumps occur to this
113 address, fill from 0xf0 to 0x100 */
114 .rept 4
115 KILL_INSN
116 .endr
117
118/* This address must remain fixed at 0x100 for glibc's syscalls to work */
119 .align LINUX_GATEWAY_ADDR
120linux_gateway_entry:
121 gate .+8, %r0 /* become privileged */
122 mtsp %r0,%sr4 /* get kernel space into sr4 */
123 mtsp %r0,%sr5 /* get kernel space into sr5 */
124 mtsp %r0,%sr6 /* get kernel space into sr6 */
125
126#ifdef CONFIG_64BIT
127 /* Store W bit on entry to the syscall in case it's a wide userland
128 * process. */
129 ssm PSW_SM_W, %r1
130 extrd,u %r1,PSW_W_BIT,1,%r1
131 /* sp must be aligned on 4, so deposit the W bit setting into
132 * the bottom of sp temporarily */
133 or,ev %r1,%r30,%r30
134 b,n 1f
135 /* The top halves of argument registers must be cleared on syscall
136 * entry from narrow executable.
137 */
138 depdi 0, 31, 32, %r26
139 depdi 0, 31, 32, %r25
140 depdi 0, 31, 32, %r24
141 depdi 0, 31, 32, %r23
142 depdi 0, 31, 32, %r22
143 depdi 0, 31, 32, %r21
1441:
145#endif
146
147 /* We use a rsm/ssm pair to prevent sr3 from being clobbered
148 * by external interrupts.
149 */
150 mfsp %sr7,%r1 /* save user sr7 */
151 rsm PSW_SM_I, %r0 /* disable interrupts */
152 mtsp %r1,%sr3 /* and store it in sr3 */
153
154 mfctl %cr30,%r1
155 xor %r1,%r30,%r30 /* ye olde xor trick */
156 xor %r1,%r30,%r1
157 xor %r1,%r30,%r30
158
159 LDREG TASK_STACK(%r30),%r30 /* set up kernel stack */
160 ldo FRAME_SIZE(%r30),%r30
161 /* N.B.: It is critical that we don't set sr7 to 0 until r30
162 * contains a valid kernel stack pointer. It is also
163 * critical that we don't start using the kernel stack
164 * until after sr7 has been set to 0.
165 */
166
167 mtsp %r0,%sr7 /* get kernel space into sr7 */
168 ssm PSW_SM_I, %r0 /* enable interrupts */
169 STREGM %r1,FRAME_SIZE(%r30) /* save r1 (usp) here for now */
170 mfctl %cr30,%r1 /* get task ptr in %r1 */
171
172 /* Save some registers for sigcontext and potential task
173 switch (see entry.S for the details of which ones are
174 saved/restored). TASK_PT_PSW is zeroed so we can see whether
175 a process is on a syscall or not. For an interrupt the real
176 PSW value is stored. This is needed for gdb and sys_ptrace. */
177 STREG %r0, TASK_PT_PSW(%r1)
178 STREG %r2, TASK_PT_GR2(%r1) /* preserve rp */
179 STREG %r19, TASK_PT_GR19(%r1)
180
181 LDREGM -FRAME_SIZE(%r30), %r2 /* get users sp back */
182#ifdef CONFIG_64BIT
183 extrd,u %r2,63,1,%r19 /* W hidden in bottom bit */
184#if 0
185 xor %r19,%r2,%r2 /* clear bottom bit */
186 depd,z %r19,1,1,%r19
187 std %r19,TASK_PT_PSW(%r1)
188#endif
189#endif
190 STREG %r2, TASK_PT_GR30(%r1) /* ... and save it */
191
192 STREG %r20, TASK_PT_GR20(%r1) /* Syscall number */
193 STREG %r21, TASK_PT_GR21(%r1)
194 STREG %r22, TASK_PT_GR22(%r1)
195 STREG %r23, TASK_PT_GR23(%r1) /* 4th argument */
196 STREG %r24, TASK_PT_GR24(%r1) /* 3rd argument */
197 STREG %r25, TASK_PT_GR25(%r1) /* 2nd argument */
198 STREG %r26, TASK_PT_GR26(%r1) /* 1st argument */
199 STREG %r27, TASK_PT_GR27(%r1) /* user dp */
200 STREG %r28, TASK_PT_GR28(%r1) /* return value 0 */
201 STREG %r0, TASK_PT_ORIG_R28(%r1) /* don't prohibit restarts */
202 STREG %r29, TASK_PT_GR29(%r1) /* return value 1 */
203 STREG %r31, TASK_PT_GR31(%r1) /* preserve syscall return ptr */
204
205 ldo TASK_PT_FR0(%r1), %r27 /* save fpregs from the kernel */
206 save_fp %r27 /* or potential task switch */
207
208 mfctl %cr11, %r27 /* i.e. SAR */
209 STREG %r27, TASK_PT_SAR(%r1)
210
211 loadgp
212
213#ifdef CONFIG_64BIT
214 ldo -16(%r30),%r29 /* Reference param save area */
215 copy %r19,%r2 /* W bit back to r2 */
216#else
217 /* no need to save these on stack in wide mode because the first 8
218 * args are passed in registers */
219 stw %r22, -52(%r30) /* 5th argument */
220 stw %r21, -56(%r30) /* 6th argument */
221#endif
222
223 /* Are we being ptraced? */
224 mfctl %cr30, %r1
225 LDREG TASK_TI_FLAGS(%r1),%r1
226 ldi _TIF_SYSCALL_TRACE_MASK, %r19
227 and,COND(=) %r1, %r19, %r0
228 b,n .Ltracesys
229
230 /* Note! We cannot use the syscall table that is mapped
231 nearby since the gateway page is mapped execute-only. */
232
233#ifdef CONFIG_64BIT
234 ldil L%sys_call_table, %r1
235 or,= %r2,%r2,%r2
236 addil L%(sys_call_table64-sys_call_table), %r1
237 ldo R%sys_call_table(%r1), %r19
238 or,= %r2,%r2,%r2
239 ldo R%sys_call_table64(%r1), %r19
240#else
241 load32 sys_call_table, %r19
242#endif
243 comiclr,>> __NR_Linux_syscalls, %r20, %r0
244 b,n .Lsyscall_nosys
245
246 LDREGX %r20(%r19), %r19
247
248 /* If this is a sys_rt_sigreturn call, and the signal was received
249 * when not in_syscall, then we want to return via syscall_exit_rfi,
250 * not syscall_exit. Signal no. in r20, in_syscall in r25 (see
251 * trampoline code in signal.c).
252 */
253 ldi __NR_rt_sigreturn,%r2
254 comb,= %r2,%r20,.Lrt_sigreturn
255.Lin_syscall:
256 ldil L%syscall_exit,%r2
257 be 0(%sr7,%r19)
258 ldo R%syscall_exit(%r2),%r2
259.Lrt_sigreturn:
260 comib,<> 0,%r25,.Lin_syscall
261 ldil L%syscall_exit_rfi,%r2
262 be 0(%sr7,%r19)
263 ldo R%syscall_exit_rfi(%r2),%r2
264
265 /* Note! Because we are not running where we were linked, any
266 calls to functions external to this file must be indirect. To
267 be safe, we apply the opposite rule to functions within this
268 file, with local labels given to them to ensure correctness. */
269
270.Lsyscall_nosys:
271syscall_nosys:
272 ldil L%syscall_exit,%r1
273 be R%syscall_exit(%sr7,%r1)
274 ldo -ENOSYS(%r0),%r28 /* set errno */
275
276
277/* Warning! This trace code is a virtual duplicate of the code above so be
278 * sure to maintain both! */
279.Ltracesys:
280tracesys:
281 /* Need to save more registers so the debugger can see where we
282 * are. This saves only the lower 8 bits of PSW, so that the C
283 * bit is still clear on syscalls, and the D bit is set if this
284 * full register save path has been executed. We check the D
285 * bit on syscall_return_rfi to determine which registers to
286 * restore. An interrupt results in a full PSW saved with the
287 * C bit set, a non-straced syscall entry results in C and D clear
288 * in the saved PSW.
289 */
290 mfctl %cr30,%r1 /* get task ptr */
291 ssm 0,%r2
292 STREG %r2,TASK_PT_PSW(%r1) /* Lower 8 bits only!! */
293 mfsp %sr0,%r2
294 STREG %r2,TASK_PT_SR0(%r1)
295 mfsp %sr1,%r2
296 STREG %r2,TASK_PT_SR1(%r1)
297 mfsp %sr2,%r2
298 STREG %r2,TASK_PT_SR2(%r1)
299 mfsp %sr3,%r2
300 STREG %r2,TASK_PT_SR3(%r1)
301 STREG %r2,TASK_PT_SR4(%r1)
302 STREG %r2,TASK_PT_SR5(%r1)
303 STREG %r2,TASK_PT_SR6(%r1)
304 STREG %r2,TASK_PT_SR7(%r1)
305 STREG %r2,TASK_PT_IASQ0(%r1)
306 STREG %r2,TASK_PT_IASQ1(%r1)
307 LDREG TASK_PT_GR31(%r1),%r2
308 STREG %r2,TASK_PT_IAOQ0(%r1)
309 ldo 4(%r2),%r2
310 STREG %r2,TASK_PT_IAOQ1(%r1)
311 ldo TASK_REGS(%r1),%r2
312 /* reg_save %r2 */
313 STREG %r3,PT_GR3(%r2)
314 STREG %r4,PT_GR4(%r2)
315 STREG %r5,PT_GR5(%r2)
316 STREG %r6,PT_GR6(%r2)
317 STREG %r7,PT_GR7(%r2)
318 STREG %r8,PT_GR8(%r2)
319 STREG %r9,PT_GR9(%r2)
320 STREG %r10,PT_GR10(%r2)
321 STREG %r11,PT_GR11(%r2)
322 STREG %r12,PT_GR12(%r2)
323 STREG %r13,PT_GR13(%r2)
324 STREG %r14,PT_GR14(%r2)
325 STREG %r15,PT_GR15(%r2)
326 STREG %r16,PT_GR16(%r2)
327 STREG %r17,PT_GR17(%r2)
328 STREG %r18,PT_GR18(%r2)
329 /* Finished saving things for the debugger */
330
331 copy %r2,%r26
332 ldil L%do_syscall_trace_enter,%r1
333 ldil L%tracesys_next,%r2
334 be R%do_syscall_trace_enter(%sr7,%r1)
335 ldo R%tracesys_next(%r2),%r2
336
337tracesys_next:
338 /* do_syscall_trace_enter either returned the syscallno, or -1L,
339 * so we skip restoring the PT_GR20 below, since we pulled it from
340 * task->thread.regs.gr[20] above.
341 */
342 copy %ret0,%r20
343
344 mfctl %cr30,%r1 /* get task ptr */
345 LDREG TASK_PT_GR28(%r1), %r28 /* Restore return value */
346 LDREG TASK_PT_GR26(%r1), %r26 /* Restore the users args */
347 LDREG TASK_PT_GR25(%r1), %r25
348 LDREG TASK_PT_GR24(%r1), %r24
349 LDREG TASK_PT_GR23(%r1), %r23
350 LDREG TASK_PT_GR22(%r1), %r22
351 LDREG TASK_PT_GR21(%r1), %r21
352#ifdef CONFIG_64BIT
353 ldo -16(%r30),%r29 /* Reference param save area */
354#else
355 stw %r22, -52(%r30) /* 5th argument */
356 stw %r21, -56(%r30) /* 6th argument */
357#endif
358
359 cmpib,COND(=),n -1,%r20,tracesys_exit /* seccomp may have returned -1 */
360 comiclr,>> __NR_Linux_syscalls, %r20, %r0
361 b,n .Ltracesys_nosys
362
363 /* Note! We cannot use the syscall table that is mapped
364 nearby since the gateway page is mapped execute-only. */
365
366#ifdef CONFIG_64BIT
367 LDREG TASK_PT_GR30(%r1), %r19 /* get users sp back */
368 extrd,u %r19,63,1,%r2 /* W hidden in bottom bit */
369
370 ldil L%sys_call_table, %r1
371 or,= %r2,%r2,%r2
372 addil L%(sys_call_table64-sys_call_table), %r1
373 ldo R%sys_call_table(%r1), %r19
374 or,= %r2,%r2,%r2
375 ldo R%sys_call_table64(%r1), %r19
376#else
377 load32 sys_call_table, %r19
378#endif
379
380 LDREGX %r20(%r19), %r19
381
382 /* If this is a sys_rt_sigreturn call, and the signal was received
383 * when not in_syscall, then we want to return via syscall_exit_rfi,
384 * not syscall_exit. Signal no. in r20, in_syscall in r25 (see
385 * trampoline code in signal.c).
386 */
387 ldi __NR_rt_sigreturn,%r2
388 comb,= %r2,%r20,.Ltrace_rt_sigreturn
389.Ltrace_in_syscall:
390 ldil L%tracesys_exit,%r2
391 be 0(%sr7,%r19)
392 ldo R%tracesys_exit(%r2),%r2
393
394.Ltracesys_nosys:
395 ldo -ENOSYS(%r0),%r28 /* set errno */
396
397 /* Do *not* call this function on the gateway page, because it
398 makes a direct call to syscall_trace. */
399
400tracesys_exit:
401 mfctl %cr30,%r1 /* get task ptr */
402#ifdef CONFIG_64BIT
403 ldo -16(%r30),%r29 /* Reference param save area */
404#endif
405 ldo TASK_REGS(%r1),%r26
406 BL do_syscall_trace_exit,%r2
407 STREG %r28,TASK_PT_GR28(%r1) /* save return value now */
408 mfctl %cr30,%r1 /* get task ptr */
409 LDREG TASK_PT_GR28(%r1), %r28 /* Restore return val. */
410
411 ldil L%syscall_exit,%r1
412 be,n R%syscall_exit(%sr7,%r1)
413
414.Ltrace_rt_sigreturn:
415 comib,<> 0,%r25,.Ltrace_in_syscall
416 ldil L%tracesys_sigexit,%r2
417 be 0(%sr7,%r19)
418 ldo R%tracesys_sigexit(%r2),%r2
419
420tracesys_sigexit:
421 mfctl %cr30,%r1 /* get task ptr */
422#ifdef CONFIG_64BIT
423 ldo -16(%r30),%r29 /* Reference param save area */
424#endif
425 BL do_syscall_trace_exit,%r2
426 ldo TASK_REGS(%r1),%r26
427
428 ldil L%syscall_exit_rfi,%r1
429 be,n R%syscall_exit_rfi(%sr7,%r1)
430
431
432 /*********************************************************
433 32/64-bit Light-Weight-Syscall ABI
434
435 * - Indicates a hint for userspace inline asm
436 implementations.
437
438 Syscall number (caller-saves)
439 - %r20
440 * In asm clobber.
441
442 Argument registers (caller-saves)
443 - %r26, %r25, %r24, %r23, %r22
444 * In asm input.
445
446 Return registers (caller-saves)
447 - %r28 (return), %r21 (errno)
448 * In asm output.
449
450 Caller-saves registers
451 - %r1, %r27, %r29
452 - %r2 (return pointer)
453 - %r31 (ble link register)
454 * In asm clobber.
455
456 Callee-saves registers
457 - %r3-%r18
458 - %r30 (stack pointer)
459 * Not in asm clobber.
460
461 If userspace is 32-bit:
462 Callee-saves registers
463 - %r19 (32-bit PIC register)
464
465 Differences from 32-bit calling convention:
466 - Syscall number in %r20
467 - Additional argument register %r22 (arg4)
468 - Callee-saves %r19.
469
470 If userspace is 64-bit:
471 Callee-saves registers
472 - %r27 (64-bit PIC register)
473
474 Differences from 64-bit calling convention:
475 - Syscall number in %r20
476 - Additional argument register %r22 (arg4)
477 - Callee-saves %r27.
478
479 Error codes returned by entry path:
480
481 ENOSYS - r20 was an invalid LWS number.
482
483 *********************************************************/
484lws_start:
485
486#ifdef CONFIG_64BIT
487 ssm PSW_SM_W, %r1
488 extrd,u %r1,PSW_W_BIT,1,%r1
489 /* sp must be aligned on 4, so deposit the W bit setting into
490 * the bottom of sp temporarily */
491 or,od %r1,%r30,%r30
492
493 /* Clip LWS number to a 32-bit value for 32-bit processes */
494 depdi 0, 31, 32, %r20
495#endif
496
497 /* Is the lws entry number valid? */
498 comiclr,>> __NR_lws_entries, %r20, %r0
499 b,n lws_exit_nosys
500
501 /* Load table start */
502 ldil L%lws_table, %r1
503 ldo R%lws_table(%r1), %r28 /* Scratch use of r28 */
504 LDREGX %r20(%sr2,r28), %r21 /* Scratch use of r21 */
505
506 /* Jump to lws, lws table pointers already relocated */
507 be,n 0(%sr2,%r21)
508
509lws_exit_noerror:
510 lws_pagefault_enable %r1,%r21
511 stw,ma %r20, 0(%sr2,%r20)
512 ssm PSW_SM_I, %r0
513 b lws_exit
514 copy %r0, %r21
515
516lws_wouldblock:
517 ssm PSW_SM_I, %r0
518 ldo 2(%r0), %r28
519 b lws_exit
520 ldo -EAGAIN(%r0), %r21
521
522lws_pagefault:
523 lws_pagefault_enable %r1,%r21
524 stw,ma %r20, 0(%sr2,%r20)
525 ssm PSW_SM_I, %r0
526 ldo 3(%r0),%r28
527 b lws_exit
528 ldo -EAGAIN(%r0),%r21
529
530lws_fault:
531 ldo 1(%r0),%r28
532 b lws_exit
533 ldo -EFAULT(%r0),%r21
534
535lws_exit_nosys:
536 ldo -ENOSYS(%r0),%r21
537 /* Fall through: Return to userspace */
538
539lws_exit:
540#ifdef CONFIG_64BIT
541 /* decide whether to reset the wide mode bit
542 *
543 * For a syscall, the W bit is stored in the lowest bit
544 * of sp. Extract it and reset W if it is zero */
545 extrd,u,*<> %r30,63,1,%r1
546 rsm PSW_SM_W, %r0
547 /* now reset the lowest bit of sp if it was set */
548 xor %r30,%r1,%r30
549#endif
550 be,n 0(%sr7, %r31)
551
552
553
554 /***************************************************
555 Implementing 32bit CAS as an atomic operation:
556
557 %r26 - Address to examine
558 %r25 - Old value to check (old)
559 %r24 - New value to set (new)
560 %r28 - Return prev through this register.
561 %r21 - Kernel error code
562
563 %r21 returns the following error codes:
564 EAGAIN - CAS is busy, ldcw failed, try again.
565 EFAULT - Read or write failed.
566
567 If EAGAIN is returned, %r28 indicates the busy reason:
568 r28 == 1 - CAS is busy. lock contended.
569 r28 == 2 - CAS is busy. ldcw failed.
570 r28 == 3 - CAS is busy. page fault.
571
572 Scratch: r20, r28, r1
573
574 ****************************************************/
575
576 /* ELF64 Process entry path */
577lws_compare_and_swap64:
578#ifdef CONFIG_64BIT
579 b,n lws_compare_and_swap
580#else
581 /* If we are not a 64-bit kernel, then we don't
582 * have 64-bit input registers, and calling
583 * the 64-bit LWS CAS returns ENOSYS.
584 */
585 b,n lws_exit_nosys
586#endif
587
588 /* ELF32/ELF64 Process entry path */
589lws_compare_and_swap32:
590#ifdef CONFIG_64BIT
591 /* Wide mode user process? */
592 bb,<,n %sp, 31, lws_compare_and_swap
593
594 /* Clip all the input registers for 32-bit processes */
595 depdi 0, 31, 32, %r26
596 depdi 0, 31, 32, %r25
597 depdi 0, 31, 32, %r24
598#endif
599
600lws_compare_and_swap:
601 /* Trigger memory reference interruptions without writing to memory */
6021: ldw 0(%r26), %r28
6032: stbys,e %r0, 0(%r26)
604
605 /* Calculate 8-bit hash index from virtual address */
606 extru_safe %r26, 27, 8, %r20
607
608 /* Load start of lock table */
609 ldil L%lws_lock_start, %r28
610 ldo R%lws_lock_start(%r28), %r28
611
612 /* Find lock to use, the hash index is one of 0 to
613 255, multiplied by 16 (keep it 16-byte aligned)
614 and add to the lock table offset. */
615 shlw %r20, 4, %r20
616 add %r20, %r28, %r20
617
618 rsm PSW_SM_I, %r0 /* Disable interrupts */
619
620 /* Try to acquire the lock */
621 LDCW 0(%sr2,%r20), %r28
622 comclr,<> %r0, %r28, %r0
623 b,n lws_wouldblock
624
625 /* Disable page faults to prevent sleeping in critical region */
626 lws_pagefault_disable %r21,%r28
627
628 /*
629 prev = *addr;
630 if ( prev == old )
631 *addr = new;
632 return prev;
633 */
634
635 /* NOTES:
636 This all works because intr_do_signal
637 and schedule both check the return iasq
638 and see that we are on the kernel page
639 so this process is never scheduled off
640 or is ever sent any signal of any sort,
641 thus it is wholly atomic from usrspace's
642 perspective
643 */
644 /* The load and store could fail */
6453: ldw 0(%r26), %r28
646 sub,<> %r28, %r25, %r0
6474: stw %r24, 0(%r26)
648 b,n lws_exit_noerror
649
650 /* A fault occurred on load or stbys,e store */
6515: b,n lws_fault
652 ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 5b-linux_gateway_page)
653 ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 5b-linux_gateway_page)
654
655 /* A page fault occurred in critical region */
6566: b,n lws_pagefault
657 ASM_EXCEPTIONTABLE_ENTRY(3b-linux_gateway_page, 6b-linux_gateway_page)
658 ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 6b-linux_gateway_page)
659
660
661 /***************************************************
662 New CAS implementation which uses pointers and variable size
663 information. The value pointed by old and new MUST NOT change
664 while performing CAS. The lock only protects the value at %r26.
665
666 %r26 - Address to examine
667 %r25 - Pointer to the value to check (old)
668 %r24 - Pointer to the value to set (new)
669 %r23 - Size of the variable (0/1/2/3 for 8/16/32/64 bit)
670 %r28 - Return non-zero on failure
671 %r21 - Kernel error code
672
673 %r21 returns the following error codes:
674 EAGAIN - CAS is busy, ldcw failed, try again.
675 EFAULT - Read or write failed.
676
677 If EAGAIN is returned, %r28 indicates the busy reason:
678 r28 == 1 - CAS is busy. lock contended.
679 r28 == 2 - CAS is busy. ldcw failed.
680 r28 == 3 - CAS is busy. page fault.
681
682 Scratch: r20, r22, r28, r29, r1, fr4 (32bit for 64bit CAS only)
683
684 ****************************************************/
685
686lws_compare_and_swap_2:
687#ifdef CONFIG_64BIT
688 /* Wide mode user process? */
689 bb,<,n %sp, 31, cas2_begin
690
691 /* Clip the input registers for 32-bit processes. We don't
692 need to clip %r23 as we only use it for word operations */
693 depdi 0, 31, 32, %r26
694 depdi 0, 31, 32, %r25
695 depdi 0, 31, 32, %r24
696#endif
697
698cas2_begin:
699 /* Check the validity of the size pointer */
700 subi,>>= 3, %r23, %r0
701 b,n lws_exit_nosys
702
703 /* Jump to the functions which will load the old and new values into
704 registers depending on the their size */
705 shlw %r23, 2, %r29
706 blr %r29, %r0
707 nop
708
709 /* 8-bit load */
7101: ldb 0(%r25), %r25
711 b cas2_lock_start
7122: ldb 0(%r24), %r24
713 nop
714 nop
715 nop
716 nop
717 nop
718
719 /* 16-bit load */
7203: ldh 0(%r25), %r25
721 b cas2_lock_start
7224: ldh 0(%r24), %r24
723 nop
724 nop
725 nop
726 nop
727 nop
728
729 /* 32-bit load */
7305: ldw 0(%r25), %r25
731 b cas2_lock_start
7326: ldw 0(%r24), %r24
733 nop
734 nop
735 nop
736 nop
737 nop
738
739 /* 64-bit load */
740#ifdef CONFIG_64BIT
7417: ldd 0(%r25), %r25
7428: ldd 0(%r24), %r24
743#else
744 /* Load old value into r22/r23 - high/low */
7457: ldw 0(%r25), %r22
7468: ldw 4(%r25), %r23
747 /* Load new value into fr4 for atomic store later */
7489: flddx 0(%r24), %fr4
749#endif
750
751cas2_lock_start:
752 /* Trigger memory reference interruptions without writing to memory */
753 copy %r26, %r28
754 depi_safe 0, 31, 2, %r28
75510: ldw 0(%r28), %r1
75611: stbys,e %r0, 0(%r28)
757
758 /* Calculate 8-bit hash index from virtual address */
759 extru_safe %r26, 27, 8, %r20
760
761 /* Load start of lock table */
762 ldil L%lws_lock_start, %r28
763 ldo R%lws_lock_start(%r28), %r28
764
765 /* Find lock to use, the hash index is one of 0 to
766 255, multiplied by 16 (keep it 16-byte aligned)
767 and add to the lock table offset. */
768 shlw %r20, 4, %r20
769 add %r20, %r28, %r20
770
771 rsm PSW_SM_I, %r0 /* Disable interrupts */
772
773 /* Try to acquire the lock */
774 LDCW 0(%sr2,%r20), %r28
775 comclr,<> %r0, %r28, %r0
776 b,n lws_wouldblock
777
778 /* Disable page faults to prevent sleeping in critical region */
779 lws_pagefault_disable %r21,%r28
780
781 /*
782 prev = *addr;
783 if ( prev == old )
784 *addr = new;
785 return prev;
786 */
787
788 /* NOTES:
789 This all works because intr_do_signal
790 and schedule both check the return iasq
791 and see that we are on the kernel page
792 so this process is never scheduled off
793 or is ever sent any signal of any sort,
794 thus it is wholly atomic from usrspace's
795 perspective
796 */
797
798 /* Jump to the correct function */
799 blr %r29, %r0
800 /* Set %r28 as non-zero for now */
801 ldo 1(%r0),%r28
802
803 /* 8-bit CAS */
80412: ldb 0(%r26), %r29
805 sub,= %r29, %r25, %r0
806 b,n lws_exit_noerror
80713: stb %r24, 0(%r26)
808 b lws_exit_noerror
809 copy %r0, %r28
810 nop
811 nop
812
813 /* 16-bit CAS */
81414: ldh 0(%r26), %r29
815 sub,= %r29, %r25, %r0
816 b,n lws_exit_noerror
81715: sth %r24, 0(%r26)
818 b lws_exit_noerror
819 copy %r0, %r28
820 nop
821 nop
822
823 /* 32-bit CAS */
82416: ldw 0(%r26), %r29
825 sub,= %r29, %r25, %r0
826 b,n lws_exit_noerror
82717: stw %r24, 0(%r26)
828 b lws_exit_noerror
829 copy %r0, %r28
830 nop
831 nop
832
833 /* 64-bit CAS */
834#ifdef CONFIG_64BIT
83518: ldd 0(%r26), %r29
836 sub,*= %r29, %r25, %r0
837 b,n lws_exit_noerror
83819: std %r24, 0(%r26)
839 copy %r0, %r28
840#else
841 /* Compare first word */
84218: ldw 0(%r26), %r29
843 sub,= %r29, %r22, %r0
844 b,n lws_exit_noerror
845 /* Compare second word */
84619: ldw 4(%r26), %r29
847 sub,= %r29, %r23, %r0
848 b,n lws_exit_noerror
849 /* Perform the store */
85020: fstdx %fr4, 0(%r26)
851 copy %r0, %r28
852#endif
853 b lws_exit_noerror
854 copy %r0, %r28
855
856 /* A fault occurred on load or stbys,e store */
85730: b,n lws_fault
858 ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 30b-linux_gateway_page)
859 ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 30b-linux_gateway_page)
860 ASM_EXCEPTIONTABLE_ENTRY(3b-linux_gateway_page, 30b-linux_gateway_page)
861 ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 30b-linux_gateway_page)
862 ASM_EXCEPTIONTABLE_ENTRY(5b-linux_gateway_page, 30b-linux_gateway_page)
863 ASM_EXCEPTIONTABLE_ENTRY(6b-linux_gateway_page, 30b-linux_gateway_page)
864 ASM_EXCEPTIONTABLE_ENTRY(7b-linux_gateway_page, 30b-linux_gateway_page)
865 ASM_EXCEPTIONTABLE_ENTRY(8b-linux_gateway_page, 30b-linux_gateway_page)
866#ifndef CONFIG_64BIT
867 ASM_EXCEPTIONTABLE_ENTRY(9b-linux_gateway_page, 30b-linux_gateway_page)
868#endif
869
870 ASM_EXCEPTIONTABLE_ENTRY(10b-linux_gateway_page, 30b-linux_gateway_page)
871 ASM_EXCEPTIONTABLE_ENTRY(11b-linux_gateway_page, 30b-linux_gateway_page)
872
873 /* A page fault occurred in critical region */
87431: b,n lws_pagefault
875 ASM_EXCEPTIONTABLE_ENTRY(12b-linux_gateway_page, 31b-linux_gateway_page)
876 ASM_EXCEPTIONTABLE_ENTRY(13b-linux_gateway_page, 31b-linux_gateway_page)
877 ASM_EXCEPTIONTABLE_ENTRY(14b-linux_gateway_page, 31b-linux_gateway_page)
878 ASM_EXCEPTIONTABLE_ENTRY(15b-linux_gateway_page, 31b-linux_gateway_page)
879 ASM_EXCEPTIONTABLE_ENTRY(16b-linux_gateway_page, 31b-linux_gateway_page)
880 ASM_EXCEPTIONTABLE_ENTRY(17b-linux_gateway_page, 31b-linux_gateway_page)
881 ASM_EXCEPTIONTABLE_ENTRY(18b-linux_gateway_page, 31b-linux_gateway_page)
882 ASM_EXCEPTIONTABLE_ENTRY(19b-linux_gateway_page, 31b-linux_gateway_page)
883#ifndef CONFIG_64BIT
884 ASM_EXCEPTIONTABLE_ENTRY(20b-linux_gateway_page, 31b-linux_gateway_page)
885#endif
886
887
888 /***************************************************
889 LWS atomic exchange.
890
891 %r26 - Exchange address
892 %r25 - Size of the variable (0/1/2/3 for 8/16/32/64 bit)
893 %r24 - Address of new value
894 %r23 - Address of old value
895 %r28 - Return non-zero on failure
896 %r21 - Kernel error code
897
898 %r21 returns the following error codes:
899 EAGAIN - CAS is busy, ldcw failed, try again.
900 EFAULT - Read or write failed.
901
902 If EAGAIN is returned, %r28 indicates the busy reason:
903 r28 == 1 - CAS is busy. lock contended.
904 r28 == 2 - CAS is busy. ldcw failed.
905 r28 == 3 - CAS is busy. page fault.
906
907 Scratch: r20, r1
908
909 ****************************************************/
910
911lws_atomic_xchg:
912#ifdef CONFIG_64BIT
913 /* Wide mode user process? */
914 bb,<,n %sp, 31, atomic_xchg_begin
915
916 /* Clip the input registers for 32-bit processes. We don't
917 need to clip %r23 as we only use it for word operations */
918 depdi 0, 31, 32, %r26
919 depdi 0, 31, 32, %r25
920 depdi 0, 31, 32, %r24
921 depdi 0, 31, 32, %r23
922#endif
923
924atomic_xchg_begin:
925 /* Check the validity of the size pointer */
926 subi,>>= 3, %r25, %r0
927 b,n lws_exit_nosys
928
929 /* Jump to the functions which will load the old and new values into
930 registers depending on the their size */
931 shlw %r25, 2, %r1
932 blr %r1, %r0
933 nop
934
935 /* Perform exception checks */
936
937 /* 8-bit exchange */
9381: ldb 0(%r24), %r20
939 copy %r23, %r20
940 depi_safe 0, 31, 2, %r20
941 b atomic_xchg_start
9422: stbys,e %r0, 0(%r20)
943 nop
944 nop
945 nop
946
947 /* 16-bit exchange */
9483: ldh 0(%r24), %r20
949 copy %r23, %r20
950 depi_safe 0, 31, 2, %r20
951 b atomic_xchg_start
9524: stbys,e %r0, 0(%r20)
953 nop
954 nop
955 nop
956
957 /* 32-bit exchange */
9585: ldw 0(%r24), %r20
959 b atomic_xchg_start
9606: stbys,e %r0, 0(%r23)
961 nop
962 nop
963 nop
964 nop
965 nop
966
967 /* 64-bit exchange */
968#ifdef CONFIG_64BIT
9697: ldd 0(%r24), %r20
9708: stdby,e %r0, 0(%r23)
971#else
9727: ldw 0(%r24), %r20
9738: ldw 4(%r24), %r20
974 copy %r23, %r20
975 depi_safe 0, 31, 2, %r20
9769: stbys,e %r0, 0(%r20)
97710: stbys,e %r0, 4(%r20)
978#endif
979
980atomic_xchg_start:
981 /* Trigger memory reference interruptions without writing to memory */
982 copy %r26, %r28
983 depi_safe 0, 31, 2, %r28
98411: ldw 0(%r28), %r1
98512: stbys,e %r0, 0(%r28)
986
987 /* Calculate 8-bit hash index from virtual address */
988 extru_safe %r26, 27, 8, %r20
989
990 /* Load start of lock table */
991 ldil L%lws_lock_start, %r28
992 ldo R%lws_lock_start(%r28), %r28
993
994 /* Find lock to use, the hash index is one of 0 to
995 255, multiplied by 16 (keep it 16-byte aligned)
996 and add to the lock table offset. */
997 shlw %r20, 4, %r20
998 add %r20, %r28, %r20
999
1000 rsm PSW_SM_I, %r0 /* Disable interrupts */
1001
1002 /* Try to acquire the lock */
1003 LDCW 0(%sr2,%r20), %r28
1004 comclr,<> %r0, %r28, %r0
1005 b,n lws_wouldblock
1006
1007 /* Disable page faults to prevent sleeping in critical region */
1008 lws_pagefault_disable %r21,%r28
1009
1010 /* NOTES:
1011 This all works because intr_do_signal
1012 and schedule both check the return iasq
1013 and see that we are on the kernel page
1014 so this process is never scheduled off
1015 or is ever sent any signal of any sort,
1016 thus it is wholly atomic from userspace's
1017 perspective
1018 */
1019
1020 /* Jump to the correct function */
1021 blr %r1, %r0
1022 /* Set %r28 as non-zero for now */
1023 ldo 1(%r0),%r28
1024
1025 /* 8-bit exchange */
102614: ldb 0(%r26), %r1
102715: stb %r1, 0(%r23)
102815: ldb 0(%r24), %r1
102917: stb %r1, 0(%r26)
1030 b lws_exit_noerror
1031 copy %r0, %r28
1032 nop
1033 nop
1034
1035 /* 16-bit exchange */
103618: ldh 0(%r26), %r1
103719: sth %r1, 0(%r23)
103820: ldh 0(%r24), %r1
103921: sth %r1, 0(%r26)
1040 b lws_exit_noerror
1041 copy %r0, %r28
1042 nop
1043 nop
1044
1045 /* 32-bit exchange */
104622: ldw 0(%r26), %r1
104723: stw %r1, 0(%r23)
104824: ldw 0(%r24), %r1
104925: stw %r1, 0(%r26)
1050 b lws_exit_noerror
1051 copy %r0, %r28
1052 nop
1053 nop
1054
1055 /* 64-bit exchange */
1056#ifdef CONFIG_64BIT
105726: ldd 0(%r26), %r1
105827: std %r1, 0(%r23)
105928: ldd 0(%r24), %r1
106029: std %r1, 0(%r26)
1061#else
106226: flddx 0(%r26), %fr4
106327: fstdx %fr4, 0(%r23)
106428: flddx 0(%r24), %fr4
106529: fstdx %fr4, 0(%r26)
1066#endif
1067 b lws_exit_noerror
1068 copy %r0, %r28
1069
1070 /* A fault occurred on load or stbys,e store */
107130: b,n lws_fault
1072 ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 30b-linux_gateway_page)
1073 ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 30b-linux_gateway_page)
1074 ASM_EXCEPTIONTABLE_ENTRY(3b-linux_gateway_page, 30b-linux_gateway_page)
1075 ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 30b-linux_gateway_page)
1076 ASM_EXCEPTIONTABLE_ENTRY(5b-linux_gateway_page, 30b-linux_gateway_page)
1077 ASM_EXCEPTIONTABLE_ENTRY(6b-linux_gateway_page, 30b-linux_gateway_page)
1078 ASM_EXCEPTIONTABLE_ENTRY(7b-linux_gateway_page, 30b-linux_gateway_page)
1079 ASM_EXCEPTIONTABLE_ENTRY(8b-linux_gateway_page, 30b-linux_gateway_page)
1080#ifndef CONFIG_64BIT
1081 ASM_EXCEPTIONTABLE_ENTRY(9b-linux_gateway_page, 30b-linux_gateway_page)
1082 ASM_EXCEPTIONTABLE_ENTRY(10b-linux_gateway_page, 30b-linux_gateway_page)
1083#endif
1084
1085 ASM_EXCEPTIONTABLE_ENTRY(11b-linux_gateway_page, 30b-linux_gateway_page)
1086 ASM_EXCEPTIONTABLE_ENTRY(12b-linux_gateway_page, 30b-linux_gateway_page)
1087
1088 /* A page fault occurred in critical region */
108931: b,n lws_pagefault
1090 ASM_EXCEPTIONTABLE_ENTRY(14b-linux_gateway_page, 31b-linux_gateway_page)
1091 ASM_EXCEPTIONTABLE_ENTRY(15b-linux_gateway_page, 31b-linux_gateway_page)
1092 ASM_EXCEPTIONTABLE_ENTRY(16b-linux_gateway_page, 31b-linux_gateway_page)
1093 ASM_EXCEPTIONTABLE_ENTRY(17b-linux_gateway_page, 31b-linux_gateway_page)
1094 ASM_EXCEPTIONTABLE_ENTRY(18b-linux_gateway_page, 31b-linux_gateway_page)
1095 ASM_EXCEPTIONTABLE_ENTRY(19b-linux_gateway_page, 31b-linux_gateway_page)
1096 ASM_EXCEPTIONTABLE_ENTRY(20b-linux_gateway_page, 31b-linux_gateway_page)
1097 ASM_EXCEPTIONTABLE_ENTRY(21b-linux_gateway_page, 31b-linux_gateway_page)
1098 ASM_EXCEPTIONTABLE_ENTRY(22b-linux_gateway_page, 31b-linux_gateway_page)
1099 ASM_EXCEPTIONTABLE_ENTRY(23b-linux_gateway_page, 31b-linux_gateway_page)
1100 ASM_EXCEPTIONTABLE_ENTRY(24b-linux_gateway_page, 31b-linux_gateway_page)
1101 ASM_EXCEPTIONTABLE_ENTRY(25b-linux_gateway_page, 31b-linux_gateway_page)
1102 ASM_EXCEPTIONTABLE_ENTRY(26b-linux_gateway_page, 31b-linux_gateway_page)
1103 ASM_EXCEPTIONTABLE_ENTRY(27b-linux_gateway_page, 31b-linux_gateway_page)
1104 ASM_EXCEPTIONTABLE_ENTRY(28b-linux_gateway_page, 31b-linux_gateway_page)
1105 ASM_EXCEPTIONTABLE_ENTRY(29b-linux_gateway_page, 31b-linux_gateway_page)
1106
1107 /***************************************************
1108 LWS atomic store.
1109
1110 %r26 - Address to store
1111 %r25 - Size of the variable (0/1/2/3 for 8/16/32/64 bit)
1112 %r24 - Address of value to store
1113 %r28 - Return non-zero on failure
1114 %r21 - Kernel error code
1115
1116 %r21 returns the following error codes:
1117 EAGAIN - CAS is busy, ldcw failed, try again.
1118 EFAULT - Read or write failed.
1119
1120 If EAGAIN is returned, %r28 indicates the busy reason:
1121 r28 == 1 - CAS is busy. lock contended.
1122 r28 == 2 - CAS is busy. ldcw failed.
1123 r28 == 3 - CAS is busy. page fault.
1124
1125 Scratch: r20, r1
1126
1127 ****************************************************/
1128
1129lws_atomic_store:
1130#ifdef CONFIG_64BIT
1131 /* Wide mode user process? */
1132 bb,<,n %sp, 31, atomic_store_begin
1133
1134 /* Clip the input registers for 32-bit processes. We don't
1135 need to clip %r23 as we only use it for word operations */
1136 depdi 0, 31, 32, %r26
1137 depdi 0, 31, 32, %r25
1138 depdi 0, 31, 32, %r24
1139#endif
1140
1141atomic_store_begin:
1142 /* Check the validity of the size pointer */
1143 subi,>>= 3, %r25, %r0
1144 b,n lws_exit_nosys
1145
1146 shlw %r25, 1, %r1
1147 blr %r1, %r0
1148 nop
1149
1150 /* Perform exception checks */
1151
1152 /* 8-bit store */
11531: ldb 0(%r24), %r20
1154 b,n atomic_store_start
1155 nop
1156 nop
1157
1158 /* 16-bit store */
11592: ldh 0(%r24), %r20
1160 b,n atomic_store_start
1161 nop
1162 nop
1163
1164 /* 32-bit store */
11653: ldw 0(%r24), %r20
1166 b,n atomic_store_start
1167 nop
1168 nop
1169
1170 /* 64-bit store */
1171#ifdef CONFIG_64BIT
11724: ldd 0(%r24), %r20
1173#else
11744: ldw 0(%r24), %r20
11755: ldw 4(%r24), %r20
1176#endif
1177
1178atomic_store_start:
1179 /* Trigger memory reference interruptions without writing to memory */
1180 copy %r26, %r28
1181 depi_safe 0, 31, 2, %r28
11826: ldw 0(%r28), %r1
11837: stbys,e %r0, 0(%r28)
1184
1185 /* Calculate 8-bit hash index from virtual address */
1186 extru_safe %r26, 27, 8, %r20
1187
1188 /* Load start of lock table */
1189 ldil L%lws_lock_start, %r28
1190 ldo R%lws_lock_start(%r28), %r28
1191
1192 /* Find lock to use, the hash index is one of 0 to
1193 255, multiplied by 16 (keep it 16-byte aligned)
1194 and add to the lock table offset. */
1195 shlw %r20, 4, %r20
1196 add %r20, %r28, %r20
1197
1198 rsm PSW_SM_I, %r0 /* Disable interrupts */
1199
1200 /* Try to acquire the lock */
1201 LDCW 0(%sr2,%r20), %r28
1202 comclr,<> %r0, %r28, %r0
1203 b,n lws_wouldblock
1204
1205 /* Disable page faults to prevent sleeping in critical region */
1206 lws_pagefault_disable %r21,%r28
1207
1208 /* NOTES:
1209 This all works because intr_do_signal
1210 and schedule both check the return iasq
1211 and see that we are on the kernel page
1212 so this process is never scheduled off
1213 or is ever sent any signal of any sort,
1214 thus it is wholly atomic from userspace's
1215 perspective
1216 */
1217
1218 /* Jump to the correct function */
1219 blr %r1, %r0
1220 /* Set %r28 as non-zero for now */
1221 ldo 1(%r0),%r28
1222
1223 /* 8-bit store */
12249: ldb 0(%r24), %r1
122510: stb %r1, 0(%r26)
1226 b lws_exit_noerror
1227 copy %r0, %r28
1228
1229 /* 16-bit store */
123011: ldh 0(%r24), %r1
123112: sth %r1, 0(%r26)
1232 b lws_exit_noerror
1233 copy %r0, %r28
1234
1235 /* 32-bit store */
123613: ldw 0(%r24), %r1
123714: stw %r1, 0(%r26)
1238 b lws_exit_noerror
1239 copy %r0, %r28
1240
1241 /* 64-bit store */
1242#ifdef CONFIG_64BIT
124315: ldd 0(%r24), %r1
124416: std %r1, 0(%r26)
1245#else
124615: flddx 0(%r24), %fr4
124716: fstdx %fr4, 0(%r26)
1248#endif
1249 b lws_exit_noerror
1250 copy %r0, %r28
1251
1252 /* A fault occurred on load or stbys,e store */
125330: b,n lws_fault
1254 ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 30b-linux_gateway_page)
1255 ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 30b-linux_gateway_page)
1256 ASM_EXCEPTIONTABLE_ENTRY(3b-linux_gateway_page, 30b-linux_gateway_page)
1257 ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 30b-linux_gateway_page)
1258#ifndef CONFIG_64BIT
1259 ASM_EXCEPTIONTABLE_ENTRY(5b-linux_gateway_page, 30b-linux_gateway_page)
1260#endif
1261
1262 ASM_EXCEPTIONTABLE_ENTRY(6b-linux_gateway_page, 30b-linux_gateway_page)
1263 ASM_EXCEPTIONTABLE_ENTRY(7b-linux_gateway_page, 30b-linux_gateway_page)
1264
1265 /* A page fault occurred in critical region */
126631: b,n lws_pagefault
1267 ASM_EXCEPTIONTABLE_ENTRY(9b-linux_gateway_page, 31b-linux_gateway_page)
1268 ASM_EXCEPTIONTABLE_ENTRY(10b-linux_gateway_page, 31b-linux_gateway_page)
1269 ASM_EXCEPTIONTABLE_ENTRY(11b-linux_gateway_page, 31b-linux_gateway_page)
1270 ASM_EXCEPTIONTABLE_ENTRY(12b-linux_gateway_page, 31b-linux_gateway_page)
1271 ASM_EXCEPTIONTABLE_ENTRY(13b-linux_gateway_page, 31b-linux_gateway_page)
1272 ASM_EXCEPTIONTABLE_ENTRY(14b-linux_gateway_page, 31b-linux_gateway_page)
1273 ASM_EXCEPTIONTABLE_ENTRY(15b-linux_gateway_page, 31b-linux_gateway_page)
1274 ASM_EXCEPTIONTABLE_ENTRY(16b-linux_gateway_page, 31b-linux_gateway_page)
1275
1276 /* Make sure nothing else is placed on this page */
1277 .align PAGE_SIZE
1278END(linux_gateway_page)
1279ENTRY(end_linux_gateway_page)
1280
1281 /* Relocate symbols assuming linux_gateway_page is mapped
1282 to virtual address 0x0 */
1283
1284#define LWS_ENTRY(_name_) ASM_ULONG_INSN (lws_##_name_ - linux_gateway_page)
1285
1286 .section .rodata,"a"
1287
1288 .align 8
1289 /* Light-weight-syscall table */
1290 /* Start of lws table. */
1291ENTRY(lws_table)
1292 LWS_ENTRY(compare_and_swap32) /* 0 - ELF32 Atomic 32bit CAS */
1293 LWS_ENTRY(compare_and_swap64) /* 1 - ELF64 Atomic 32bit CAS */
1294 LWS_ENTRY(compare_and_swap_2) /* 2 - Atomic 64bit CAS */
1295 LWS_ENTRY(atomic_xchg) /* 3 - Atomic Exchange */
1296 LWS_ENTRY(atomic_store) /* 4 - Atomic Store */
1297END(lws_table)
1298 /* End of lws table */
1299
1300#ifdef CONFIG_64BIT
1301#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat)
1302#else
1303#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native)
1304#endif
1305#define __SYSCALL(nr, entry) ASM_ULONG_INSN entry
1306 .align 8
1307ENTRY(sys_call_table)
1308 .export sys_call_table,data
1309#include <asm/syscall_table_32.h> /* 32-bit syscalls */
1310END(sys_call_table)
1311
1312#ifdef CONFIG_64BIT
1313 .align 8
1314ENTRY(sys_call_table64)
1315#include <asm/syscall_table_64.h> /* 64-bit syscalls */
1316END(sys_call_table64)
1317#endif
1318
1319 /*
1320 All light-weight-syscall atomic operations
1321 will use this set of locks
1322
1323 NOTE: The lws_lock_start symbol must be
1324 at least 16-byte aligned for safe use
1325 with ldcw.
1326 */
1327 .section .data
1328 .align L1_CACHE_BYTES
1329ENTRY(lws_lock_start)
1330 /* lws locks */
1331 .rept 256
1332 /* Keep locks aligned at 16-bytes */
1333 .word 1
1334 .word 0
1335 .word 0
1336 .word 0
1337 .endr
1338END(lws_lock_start)
1339 .previous
1340
1341.end