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CommitLineData
1da177e4
LT
1/*
2 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
3 *
dde39798
HD
4 * System call entry code / Linux gateway page
5 * Copyright (c) Matthew Wilcox 1999 <willy@bofh.ai>
1da177e4
LT
6 * Licensed under the GNU GPL.
7 * thanks to Philipp Rumpf, Mike Shaver and various others
8 * sorry about the wall, puffin..
9 */
10
dde39798
HD
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
0013a854 33#include <asm/asm-offsets.h>
1da177e4
LT
34#include <asm/unistd.h>
35#include <asm/errno.h>
1c593571 36#include <asm/page.h>
1da177e4
LT
37#include <asm/psw.h>
38#include <asm/thread_info.h>
1da177e4
LT
39#include <asm/assembly.h>
40#include <asm/processor.h>
6a45716a 41#include <asm/cache.h>
1da177e4 42
8e9e9844
HD
43#include <linux/linkage.h>
44
1da177e4
LT
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
0b3d643f 51 .level LEVEL
8e9e9844 52
dfcf753b 53 .text
1da177e4
LT
54
55 .import syscall_exit,code
56 .import syscall_exit_rfi,code
1da177e4
LT
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
1c593571 66 .align PAGE_SIZE
8e9e9844 67ENTRY(linux_gateway_page)
1da177e4
LT
68
69 /* ADDRESS 0x00 to 0xb0 = 176 bytes / 4 bytes per insn = 44 insns */
70 .rept 44
71 KILL_INSN
72 .endr
73
f4c0346c 74 /* ADDRESS 0xb0 to 0xb8, lws uses two insns for entry */
1da177e4
LT
75 /* Light-weight-syscall entry must always be located at 0xb0 */
76 /* WARNING: Keep this number updated with table size changes */
89206491 77#define __NR_lws_entries (3)
1da177e4
LT
78
79lws_entry:
f4c0346c
JDA
80 gate lws_start, %r0 /* increase privilege */
81 depi 3, 31, 2, %r31 /* Ensure we return into user mode. */
1da177e4 82
f4c0346c
JDA
83 /* Fill from 0xb8 to 0xe0 */
84 .rept 10
1da177e4
LT
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 */
6a6e2a14 103 .align LINUX_GATEWAY_ADDR
1da177e4
LT
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 */
1da177e4 109
413059f2 110#ifdef CONFIG_64BIT
1da177e4
LT
111 /* for now we can *always* set the W bit on entry to the syscall
112 * since we don't support wide userland processes. We could
113 * also save the current SM other than in r0 and restore it on
114 * exit from the syscall, and also use that value to know
115 * whether to do narrow or wide syscalls. -PB
116 */
117 ssm PSW_SM_W, %r1
118 extrd,u %r1,PSW_W_BIT,1,%r1
119 /* sp must be aligned on 4, so deposit the W bit setting into
120 * the bottom of sp temporarily */
121 or,ev %r1,%r30,%r30
122 b,n 1f
123 /* The top halves of argument registers must be cleared on syscall
124 * entry from narrow executable.
125 */
126 depdi 0, 31, 32, %r26
127 depdi 0, 31, 32, %r25
128 depdi 0, 31, 32, %r24
129 depdi 0, 31, 32, %r23
130 depdi 0, 31, 32, %r22
131 depdi 0, 31, 32, %r21
1321:
133#endif
6ed51832
JDA
134
135 /* We use a rsm/ssm pair to prevent sr3 from being clobbered
136 * by external interrupts.
137 */
138 mfsp %sr7,%r1 /* save user sr7 */
139 rsm PSW_SM_I, %r0 /* disable interrupts */
140 mtsp %r1,%sr3 /* and store it in sr3 */
141
1da177e4
LT
142 mfctl %cr30,%r1
143 xor %r1,%r30,%r30 /* ye olde xor trick */
144 xor %r1,%r30,%r1
145 xor %r1,%r30,%r30
146
147 ldo THREAD_SZ_ALGN+FRAME_SIZE(%r30),%r30 /* set up kernel stack */
148
149 /* N.B.: It is critical that we don't set sr7 to 0 until r30
150 * contains a valid kernel stack pointer. It is also
151 * critical that we don't start using the kernel stack
152 * until after sr7 has been set to 0.
153 */
154
155 mtsp %r0,%sr7 /* get kernel space into sr7 */
6ed51832 156 ssm PSW_SM_I, %r0 /* enable interrupts */
1da177e4
LT
157 STREGM %r1,FRAME_SIZE(%r30) /* save r1 (usp) here for now */
158 mfctl %cr30,%r1 /* get task ptr in %r1 */
159 LDREG TI_TASK(%r1),%r1
160
161 /* Save some registers for sigcontext and potential task
162 switch (see entry.S for the details of which ones are
163 saved/restored). TASK_PT_PSW is zeroed so we can see whether
164 a process is on a syscall or not. For an interrupt the real
165 PSW value is stored. This is needed for gdb and sys_ptrace. */
166 STREG %r0, TASK_PT_PSW(%r1)
167 STREG %r2, TASK_PT_GR2(%r1) /* preserve rp */
168 STREG %r19, TASK_PT_GR19(%r1)
169
170 LDREGM -FRAME_SIZE(%r30), %r2 /* get users sp back */
413059f2 171#ifdef CONFIG_64BIT
1da177e4
LT
172 extrd,u %r2,63,1,%r19 /* W hidden in bottom bit */
173#if 0
174 xor %r19,%r2,%r2 /* clear bottom bit */
175 depd,z %r19,1,1,%r19
176 std %r19,TASK_PT_PSW(%r1)
177#endif
178#endif
179 STREG %r2, TASK_PT_GR30(%r1) /* ... and save it */
180
aa0eecb0 181 STREG %r20, TASK_PT_GR20(%r1) /* Syscall number */
1da177e4
LT
182 STREG %r21, TASK_PT_GR21(%r1)
183 STREG %r22, TASK_PT_GR22(%r1)
184 STREG %r23, TASK_PT_GR23(%r1) /* 4th argument */
185 STREG %r24, TASK_PT_GR24(%r1) /* 3rd argument */
186 STREG %r25, TASK_PT_GR25(%r1) /* 2nd argument */
187 STREG %r26, TASK_PT_GR26(%r1) /* 1st argument */
188 STREG %r27, TASK_PT_GR27(%r1) /* user dp */
189 STREG %r28, TASK_PT_GR28(%r1) /* return value 0 */
00df111e 190 STREG %r0, TASK_PT_ORIG_R28(%r1) /* don't prohibit restarts */
1da177e4
LT
191 STREG %r29, TASK_PT_GR29(%r1) /* return value 1 */
192 STREG %r31, TASK_PT_GR31(%r1) /* preserve syscall return ptr */
193
194 ldo TASK_PT_FR0(%r1), %r27 /* save fpregs from the kernel */
195 save_fp %r27 /* or potential task switch */
196
197 mfctl %cr11, %r27 /* i.e. SAR */
198 STREG %r27, TASK_PT_SAR(%r1)
199
200 loadgp
201
413059f2 202#ifdef CONFIG_64BIT
1da177e4
LT
203 ldo -16(%r30),%r29 /* Reference param save area */
204 copy %r19,%r2 /* W bit back to r2 */
205#else
206 /* no need to save these on stack in wide mode because the first 8
207 * args are passed in registers */
208 stw %r22, -52(%r30) /* 5th argument */
209 stw %r21, -56(%r30) /* 6th argument */
210#endif
211
212 /* Are we being ptraced? */
213 mfctl %cr30, %r1
64482bd8
AV
214 LDREG TI_FLAGS(%r1),%r1
215 ldi _TIF_SYSCALL_TRACE_MASK, %r19
216 and,COND(=) %r1, %r19, %r0
217 b,n .Ltracesys
1da177e4
LT
218
219 /* Note! We cannot use the syscall table that is mapped
220 nearby since the gateway page is mapped execute-only. */
221
413059f2 222#ifdef CONFIG_64BIT
1da177e4
LT
223 ldil L%sys_call_table, %r1
224 or,= %r2,%r2,%r2
225 addil L%(sys_call_table64-sys_call_table), %r1
226 ldo R%sys_call_table(%r1), %r19
227 or,= %r2,%r2,%r2
228 ldo R%sys_call_table64(%r1), %r19
229#else
230 ldil L%sys_call_table, %r1
231 ldo R%sys_call_table(%r1), %r19
232#endif
3bb457af 233 comiclr,>> __NR_Linux_syscalls, %r20, %r0
1da177e4
LT
234 b,n .Lsyscall_nosys
235
236 LDREGX %r20(%r19), %r19
237
238 /* If this is a sys_rt_sigreturn call, and the signal was received
239 * when not in_syscall, then we want to return via syscall_exit_rfi,
240 * not syscall_exit. Signal no. in r20, in_syscall in r25 (see
241 * trampoline code in signal.c).
242 */
243 ldi __NR_rt_sigreturn,%r2
244 comb,= %r2,%r20,.Lrt_sigreturn
245.Lin_syscall:
246 ldil L%syscall_exit,%r2
247 be 0(%sr7,%r19)
248 ldo R%syscall_exit(%r2),%r2
249.Lrt_sigreturn:
250 comib,<> 0,%r25,.Lin_syscall
251 ldil L%syscall_exit_rfi,%r2
252 be 0(%sr7,%r19)
253 ldo R%syscall_exit_rfi(%r2),%r2
254
255 /* Note! Because we are not running where we were linked, any
256 calls to functions external to this file must be indirect. To
257 be safe, we apply the opposite rule to functions within this
258 file, with local labels given to them to ensure correctness. */
259
260.Lsyscall_nosys:
261syscall_nosys:
262 ldil L%syscall_exit,%r1
263 be R%syscall_exit(%sr7,%r1)
264 ldo -ENOSYS(%r0),%r28 /* set errno */
265
266
267/* Warning! This trace code is a virtual duplicate of the code above so be
268 * sure to maintain both! */
269.Ltracesys:
270tracesys:
271 /* Need to save more registers so the debugger can see where we
272 * are. This saves only the lower 8 bits of PSW, so that the C
273 * bit is still clear on syscalls, and the D bit is set if this
274 * full register save path has been executed. We check the D
275 * bit on syscall_return_rfi to determine which registers to
276 * restore. An interrupt results in a full PSW saved with the
277 * C bit set, a non-straced syscall entry results in C and D clear
278 * in the saved PSW.
279 */
280 ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
281 LDREG TI_TASK(%r1), %r1
282 ssm 0,%r2
283 STREG %r2,TASK_PT_PSW(%r1) /* Lower 8 bits only!! */
284 mfsp %sr0,%r2
285 STREG %r2,TASK_PT_SR0(%r1)
286 mfsp %sr1,%r2
287 STREG %r2,TASK_PT_SR1(%r1)
288 mfsp %sr2,%r2
289 STREG %r2,TASK_PT_SR2(%r1)
290 mfsp %sr3,%r2
291 STREG %r2,TASK_PT_SR3(%r1)
292 STREG %r2,TASK_PT_SR4(%r1)
293 STREG %r2,TASK_PT_SR5(%r1)
294 STREG %r2,TASK_PT_SR6(%r1)
295 STREG %r2,TASK_PT_SR7(%r1)
296 STREG %r2,TASK_PT_IASQ0(%r1)
297 STREG %r2,TASK_PT_IASQ1(%r1)
298 LDREG TASK_PT_GR31(%r1),%r2
299 STREG %r2,TASK_PT_IAOQ0(%r1)
300 ldo 4(%r2),%r2
301 STREG %r2,TASK_PT_IAOQ1(%r1)
302 ldo TASK_REGS(%r1),%r2
303 /* reg_save %r2 */
304 STREG %r3,PT_GR3(%r2)
305 STREG %r4,PT_GR4(%r2)
306 STREG %r5,PT_GR5(%r2)
307 STREG %r6,PT_GR6(%r2)
308 STREG %r7,PT_GR7(%r2)
309 STREG %r8,PT_GR8(%r2)
310 STREG %r9,PT_GR9(%r2)
311 STREG %r10,PT_GR10(%r2)
312 STREG %r11,PT_GR11(%r2)
313 STREG %r12,PT_GR12(%r2)
314 STREG %r13,PT_GR13(%r2)
315 STREG %r14,PT_GR14(%r2)
316 STREG %r15,PT_GR15(%r2)
317 STREG %r16,PT_GR16(%r2)
318 STREG %r17,PT_GR17(%r2)
319 STREG %r18,PT_GR18(%r2)
320 /* Finished saving things for the debugger */
321
2798af1a
KM
322 copy %r2,%r26
323 ldil L%do_syscall_trace_enter,%r1
1da177e4 324 ldil L%tracesys_next,%r2
2798af1a 325 be R%do_syscall_trace_enter(%sr7,%r1)
1da177e4
LT
326 ldo R%tracesys_next(%r2),%r2
327
2798af1a
KM
328tracesys_next:
329 /* do_syscall_trace_enter either returned the syscallno, or -1L,
330 * so we skip restoring the PT_GR20 below, since we pulled it from
331 * task->thread.regs.gr[20] above.
332 */
333 copy %ret0,%r20
1da177e4
LT
334 ldil L%sys_call_table,%r1
335 ldo R%sys_call_table(%r1), %r19
336
337 ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
338 LDREG TI_TASK(%r1), %r1
910cd32e 339 LDREG TASK_PT_GR28(%r1), %r28 /* Restore return value */
1da177e4
LT
340 LDREG TASK_PT_GR26(%r1), %r26 /* Restore the users args */
341 LDREG TASK_PT_GR25(%r1), %r25
342 LDREG TASK_PT_GR24(%r1), %r24
343 LDREG TASK_PT_GR23(%r1), %r23
1da177e4
LT
344 LDREG TASK_PT_GR22(%r1), %r22
345 LDREG TASK_PT_GR21(%r1), %r21
52ab532e 346#ifdef CONFIG_64BIT
1da177e4 347 ldo -16(%r30),%r29 /* Reference param save area */
52ab532e
AV
348#else
349 stw %r22, -52(%r30) /* 5th argument */
350 stw %r21, -56(%r30) /* 6th argument */
1da177e4
LT
351#endif
352
910cd32e 353 cmpib,COND(=),n -1,%r20,tracesys_exit /* seccomp may have returned -1 */
f0b22d1b 354 comiclr,>> __NR_Linux_syscalls, %r20, %r0
98e8b6c9 355 b,n .Ltracesys_nosys
1da177e4
LT
356
357 LDREGX %r20(%r19), %r19
358
359 /* If this is a sys_rt_sigreturn call, and the signal was received
360 * when not in_syscall, then we want to return via syscall_exit_rfi,
361 * not syscall_exit. Signal no. in r20, in_syscall in r25 (see
362 * trampoline code in signal.c).
363 */
364 ldi __NR_rt_sigreturn,%r2
365 comb,= %r2,%r20,.Ltrace_rt_sigreturn
366.Ltrace_in_syscall:
367 ldil L%tracesys_exit,%r2
368 be 0(%sr7,%r19)
369 ldo R%tracesys_exit(%r2),%r2
370
98e8b6c9
HD
371.Ltracesys_nosys:
372 ldo -ENOSYS(%r0),%r28 /* set errno */
373
1da177e4
LT
374 /* Do *not* call this function on the gateway page, because it
375 makes a direct call to syscall_trace. */
376
377tracesys_exit:
378 ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
379 LDREG TI_TASK(%r1), %r1
413059f2 380#ifdef CONFIG_64BIT
1da177e4
LT
381 ldo -16(%r30),%r29 /* Reference param save area */
382#endif
2798af1a 383 ldo TASK_REGS(%r1),%r26
337685e5 384 BL do_syscall_trace_exit,%r2
1da177e4
LT
385 STREG %r28,TASK_PT_GR28(%r1) /* save return value now */
386 ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
387 LDREG TI_TASK(%r1), %r1
388 LDREG TASK_PT_GR28(%r1), %r28 /* Restore return val. */
389
390 ldil L%syscall_exit,%r1
391 be,n R%syscall_exit(%sr7,%r1)
392
393.Ltrace_rt_sigreturn:
394 comib,<> 0,%r25,.Ltrace_in_syscall
395 ldil L%tracesys_sigexit,%r2
396 be 0(%sr7,%r19)
397 ldo R%tracesys_sigexit(%r2),%r2
398
399tracesys_sigexit:
400 ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
5837d42f 401 LDREG TI_TASK(%r1), %r1
413059f2 402#ifdef CONFIG_64BIT
1da177e4
LT
403 ldo -16(%r30),%r29 /* Reference param save area */
404#endif
337685e5 405 BL do_syscall_trace_exit,%r2
2798af1a 406 ldo TASK_REGS(%r1),%r26
1da177e4
LT
407
408 ldil L%syscall_exit_rfi,%r1
409 be,n R%syscall_exit_rfi(%sr7,%r1)
410
411
412 /*********************************************************
c84c3a69 413 32/64-bit Light-Weight-Syscall ABI
1da177e4 414
c84c3a69
HD
415 * - Indicates a hint for userspace inline asm
416 implementations.
1da177e4 417
c84c3a69
HD
418 Syscall number (caller-saves)
419 - %r20
420 * In asm clobber.
1da177e4 421
c84c3a69
HD
422 Argument registers (caller-saves)
423 - %r26, %r25, %r24, %r23, %r22
424 * In asm input.
425
426 Return registers (caller-saves)
427 - %r28 (return), %r21 (errno)
428 * In asm output.
429
430 Caller-saves registers
431 - %r1, %r27, %r29
432 - %r2 (return pointer)
433 - %r31 (ble link register)
434 * In asm clobber.
435
436 Callee-saves registers
437 - %r3-%r18
438 - %r30 (stack pointer)
439 * Not in asm clobber.
440
441 If userspace is 32-bit:
442 Callee-saves registers
443 - %r19 (32-bit PIC register)
444
445 Differences from 32-bit calling convention:
446 - Syscall number in %r20
447 - Additional argument register %r22 (arg4)
448 - Callee-saves %r19.
449
450 If userspace is 64-bit:
451 Callee-saves registers
452 - %r27 (64-bit PIC register)
453
454 Differences from 64-bit calling convention:
455 - Syscall number in %r20
456 - Additional argument register %r22 (arg4)
457 - Callee-saves %r27.
1da177e4
LT
458
459 Error codes returned by entry path:
460
461 ENOSYS - r20 was an invalid LWS number.
462
463 *********************************************************/
464lws_start:
1da177e4 465
413059f2 466#ifdef CONFIG_64BIT
1da177e4
LT
467 /* FIXME: If we are a 64-bit kernel just
468 * turn this on unconditionally.
469 */
470 ssm PSW_SM_W, %r1
471 extrd,u %r1,PSW_W_BIT,1,%r1
472 /* sp must be aligned on 4, so deposit the W bit setting into
473 * the bottom of sp temporarily */
474 or,ev %r1,%r30,%r30
475
476 /* Clip LWS number to a 32-bit value always */
477 depdi 0, 31, 32, %r20
478#endif
479
480 /* Is the lws entry number valid? */
f4c0346c 481 comiclr,>> __NR_lws_entries, %r20, %r0
1da177e4
LT
482 b,n lws_exit_nosys
483
1da177e4
LT
484 /* Load table start */
485 ldil L%lws_table, %r1
486 ldo R%lws_table(%r1), %r28 /* Scratch use of r28 */
487 LDREGX %r20(%sr2,r28), %r21 /* Scratch use of r21 */
488
489 /* Jump to lws, lws table pointers already relocated */
490 be,n 0(%sr2,%r21)
491
492lws_exit_nosys:
493 ldo -ENOSYS(%r0),%r21 /* set errno */
494 /* Fall through: Return to userspace */
495
496lws_exit:
413059f2 497#ifdef CONFIG_64BIT
1da177e4
LT
498 /* decide whether to reset the wide mode bit
499 *
500 * For a syscall, the W bit is stored in the lowest bit
501 * of sp. Extract it and reset W if it is zero */
502 extrd,u,*<> %r30,63,1,%r1
503 rsm PSW_SM_W, %r0
504 /* now reset the lowest bit of sp if it was set */
505 xor %r30,%r1,%r30
506#endif
f4c0346c 507 be,n 0(%sr7, %r31)
1da177e4
LT
508
509
510
511 /***************************************************
89206491 512 Implementing 32bit CAS as an atomic operation:
1da177e4
LT
513
514 %r26 - Address to examine
515 %r25 - Old value to check (old)
516 %r24 - New value to set (new)
517 %r28 - Return prev through this register.
518 %r21 - Kernel error code
519
520 If debugging is DISabled:
521
522 %r21 has the following meanings:
523
524 EAGAIN - CAS is busy, ldcw failed, try again.
525 EFAULT - Read or write failed.
526
527 If debugging is enabled:
528
529 EDEADLOCK - CAS called recursively.
530 EAGAIN && r28 == 1 - CAS is busy. Lock contended.
531 EAGAIN && r28 == 2 - CAS is busy. ldcw failed.
532 EFAULT - Read or write failed.
533
534 Scratch: r20, r28, r1
535
536 ****************************************************/
537
538 /* Do not enable LWS debugging */
539#define ENABLE_LWS_DEBUG 0
540
541 /* ELF64 Process entry path */
542lws_compare_and_swap64:
413059f2 543#ifdef CONFIG_64BIT
1da177e4
LT
544 b,n lws_compare_and_swap
545#else
546 /* If we are not a 64-bit kernel, then we don't
c84c3a69
HD
547 * have 64-bit input registers, and calling
548 * the 64-bit LWS CAS returns ENOSYS.
1da177e4
LT
549 */
550 b,n lws_exit_nosys
551#endif
552
553 /* ELF32 Process entry path */
554lws_compare_and_swap32:
413059f2 555#ifdef CONFIG_64BIT
1da177e4
LT
556 /* Clip all the input registers */
557 depdi 0, 31, 32, %r26
558 depdi 0, 31, 32, %r25
559 depdi 0, 31, 32, %r24
560#endif
561
562lws_compare_and_swap:
1da177e4
LT
563 /* Load start of lock table */
564 ldil L%lws_lock_start, %r20
565 ldo R%lws_lock_start(%r20), %r28
566
567 /* Extract four bits from r26 and hash lock (Bits 4-7) */
568 extru %r26, 27, 4, %r20
569
570 /* Find lock to use, the hash is either one of 0 to
571 15, multiplied by 16 (keep it 16-byte aligned)
572 and add to the lock table offset. */
573 shlw %r20, 4, %r20
574 add %r20, %r28, %r20
575
b5e8b733 576# if ENABLE_LWS_DEBUG
1da177e4
LT
577 /*
578 DEBUG, check for deadlock!
579 If the thread register values are the same
580 then we were the one that locked it last and
581 this is a recurisve call that will deadlock.
582 We *must* giveup this call and fail.
583 */
584 ldw 4(%sr2,%r20), %r28 /* Load thread register */
aa0eecb0 585 /* WARNING: If cr27 cycles to the same value we have problems */
1da177e4
LT
586 mfctl %cr27, %r21 /* Get current thread register */
587 cmpb,<>,n %r21, %r28, cas_lock /* Called recursive? */
588 b lws_exit /* Return error! */
589 ldo -EDEADLOCK(%r0), %r21
590cas_lock:
591 cmpb,=,n %r0, %r28, cas_nocontend /* Is nobody using it? */
592 ldo 1(%r0), %r28 /* 1st case */
593 b lws_exit /* Contended... */
594 ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
595cas_nocontend:
596# endif
597/* ENABLE_LWS_DEBUG */
598
c776cd89
JDA
599 rsm PSW_SM_I, %r0 /* Disable interrupts */
600 /* COW breaks can cause contention on UP systems */
64f49532 601 LDCW 0(%sr2,%r20), %r28 /* Try to acquire the lock */
1da177e4
LT
602 cmpb,<>,n %r0, %r28, cas_action /* Did we get it? */
603cas_wouldblock:
604 ldo 2(%r0), %r28 /* 2nd case */
c776cd89 605 ssm PSW_SM_I, %r0
1da177e4
LT
606 b lws_exit /* Contended... */
607 ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
1da177e4
LT
608
609 /*
610 prev = *addr;
611 if ( prev == old )
612 *addr = new;
613 return prev;
614 */
615
616 /* NOTES:
617 This all works becuse intr_do_signal
618 and schedule both check the return iasq
619 and see that we are on the kernel page
620 so this process is never scheduled off
621 or is ever sent any signal of any sort,
622 thus it is wholly atomic from usrspaces
623 perspective
624 */
625cas_action:
b5e8b733 626#if defined CONFIG_SMP && ENABLE_LWS_DEBUG
1da177e4
LT
627 /* DEBUG */
628 mfctl %cr27, %r1
629 stw %r1, 4(%sr2,%r20)
630#endif
631 /* The load and store could fail */
f4125cfd 6321: ldw,ma 0(%r26), %r28
1da177e4 633 sub,<> %r28, %r25, %r0
f4125cfd 6342: stw,ma %r24, 0(%r26)
1da177e4 635 /* Free lock */
c776cd89 636 stw,ma %r20, 0(%sr2,%r20)
f4c0346c 637#if ENABLE_LWS_DEBUG
1da177e4
LT
638 /* Clear thread register indicator */
639 stw %r0, 4(%sr2,%r20)
1da177e4 640#endif
c776cd89
JDA
641 /* Enable interrupts */
642 ssm PSW_SM_I, %r0
1da177e4
LT
643 /* Return to userspace, set no error */
644 b lws_exit
645 copy %r0, %r21
646
6473:
25985edc 648 /* Error occurred on load or store */
1da177e4
LT
649 /* Free lock */
650 stw %r20, 0(%sr2,%r20)
f4c0346c 651#if ENABLE_LWS_DEBUG
1da177e4 652 stw %r0, 4(%sr2,%r20)
1da177e4 653#endif
c776cd89 654 ssm PSW_SM_I, %r0
1da177e4
LT
655 b lws_exit
656 ldo -EFAULT(%r0),%r21 /* set errno */
657 nop
658 nop
659 nop
660 nop
661
662 /* Two exception table entries, one for the load,
663 the other for the store. Either return -EFAULT.
664 Each of the entries must be relocated. */
61dbbaeb
HD
665 ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 3b-linux_gateway_page)
666 ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 3b-linux_gateway_page)
1da177e4 667
1da177e4 668
89206491
GM
669 /***************************************************
670 New CAS implementation which uses pointers and variable size
671 information. The value pointed by old and new MUST NOT change
672 while performing CAS. The lock only protect the value at %r26.
673
674 %r26 - Address to examine
675 %r25 - Pointer to the value to check (old)
676 %r24 - Pointer to the value to set (new)
677 %r23 - Size of the variable (0/1/2/3 for 8/16/32/64 bit)
678 %r28 - Return non-zero on failure
679 %r21 - Kernel error code
680
681 %r21 has the following meanings:
682
683 EAGAIN - CAS is busy, ldcw failed, try again.
684 EFAULT - Read or write failed.
685
686 Scratch: r20, r22, r28, r29, r1, fr4 (32bit for 64bit CAS only)
687
688 ****************************************************/
689
690 /* ELF32 Process entry path */
691lws_compare_and_swap_2:
692#ifdef CONFIG_64BIT
693 /* Clip the input registers */
694 depdi 0, 31, 32, %r26
695 depdi 0, 31, 32, %r25
696 depdi 0, 31, 32, %r24
697 depdi 0, 31, 32, %r23
698#endif
699
700 /* Check the validity of the size pointer */
701 subi,>>= 4, %r23, %r0
702 b,n lws_exit_nosys
703
704 /* Jump to the functions which will load the old and new values into
705 registers depending on the their size */
706 shlw %r23, 2, %r29
707 blr %r29, %r0
708 nop
709
710 /* 8bit load */
f4125cfd 7114: ldb 0(%r25), %r25
89206491 712 b cas2_lock_start
f4125cfd 7135: ldb 0(%r24), %r24
89206491
GM
714 nop
715 nop
716 nop
717 nop
718 nop
719
720 /* 16bit load */
f4125cfd 7216: ldh 0(%r25), %r25
89206491 722 b cas2_lock_start
f4125cfd 7237: ldh 0(%r24), %r24
89206491
GM
724 nop
725 nop
726 nop
727 nop
728 nop
729
730 /* 32bit load */
f4125cfd 7318: ldw 0(%r25), %r25
89206491 732 b cas2_lock_start
f4125cfd 7339: ldw 0(%r24), %r24
89206491
GM
734 nop
735 nop
736 nop
737 nop
738 nop
739
740 /* 64bit load */
741#ifdef CONFIG_64BIT
f4125cfd
JDA
74210: ldd 0(%r25), %r25
74311: ldd 0(%r24), %r24
89206491
GM
744#else
745 /* Load new value into r22/r23 - high/low */
f4125cfd
JDA
74610: ldw 0(%r25), %r22
74711: ldw 4(%r25), %r23
89206491 748 /* Load new value into fr4 for atomic store later */
f4125cfd 74912: flddx 0(%r24), %fr4
89206491
GM
750#endif
751
752cas2_lock_start:
753 /* Load start of lock table */
754 ldil L%lws_lock_start, %r20
755 ldo R%lws_lock_start(%r20), %r28
756
757 /* Extract four bits from r26 and hash lock (Bits 4-7) */
758 extru %r26, 27, 4, %r20
759
760 /* Find lock to use, the hash is either one of 0 to
761 15, multiplied by 16 (keep it 16-byte aligned)
762 and add to the lock table offset. */
763 shlw %r20, 4, %r20
764 add %r20, %r28, %r20
765
766 rsm PSW_SM_I, %r0 /* Disable interrupts */
767 /* COW breaks can cause contention on UP systems */
768 LDCW 0(%sr2,%r20), %r28 /* Try to acquire the lock */
769 cmpb,<>,n %r0, %r28, cas2_action /* Did we get it? */
770cas2_wouldblock:
771 ldo 2(%r0), %r28 /* 2nd case */
772 ssm PSW_SM_I, %r0
773 b lws_exit /* Contended... */
774 ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
775
776 /*
777 prev = *addr;
778 if ( prev == old )
779 *addr = new;
780 return prev;
781 */
782
783 /* NOTES:
784 This all works becuse intr_do_signal
785 and schedule both check the return iasq
786 and see that we are on the kernel page
787 so this process is never scheduled off
788 or is ever sent any signal of any sort,
789 thus it is wholly atomic from usrspaces
790 perspective
791 */
792cas2_action:
793 /* Jump to the correct function */
794 blr %r29, %r0
795 /* Set %r28 as non-zero for now */
796 ldo 1(%r0),%r28
797
798 /* 8bit CAS */
f4125cfd 79913: ldb,ma 0(%r26), %r29
89206491
GM
800 sub,= %r29, %r25, %r0
801 b,n cas2_end
f4125cfd 80214: stb,ma %r24, 0(%r26)
89206491
GM
803 b cas2_end
804 copy %r0, %r28
805 nop
806 nop
807
808 /* 16bit CAS */
f4125cfd 80915: ldh,ma 0(%r26), %r29
89206491
GM
810 sub,= %r29, %r25, %r0
811 b,n cas2_end
f4125cfd 81216: sth,ma %r24, 0(%r26)
89206491
GM
813 b cas2_end
814 copy %r0, %r28
815 nop
816 nop
817
818 /* 32bit CAS */
f4125cfd 81917: ldw,ma 0(%r26), %r29
89206491
GM
820 sub,= %r29, %r25, %r0
821 b,n cas2_end
f4125cfd 82218: stw,ma %r24, 0(%r26)
89206491
GM
823 b cas2_end
824 copy %r0, %r28
825 nop
826 nop
827
828 /* 64bit CAS */
829#ifdef CONFIG_64BIT
f4125cfd 83019: ldd,ma 0(%r26), %r29
1b59ddfc 831 sub,*= %r29, %r25, %r0
89206491 832 b,n cas2_end
f4125cfd 83320: std,ma %r24, 0(%r26)
89206491
GM
834 copy %r0, %r28
835#else
836 /* Compare first word */
f4125cfd 83719: ldw,ma 0(%r26), %r29
89206491
GM
838 sub,= %r29, %r22, %r0
839 b,n cas2_end
840 /* Compare second word */
f4125cfd 84120: ldw,ma 4(%r26), %r29
89206491
GM
842 sub,= %r29, %r23, %r0
843 b,n cas2_end
844 /* Perform the store */
f4125cfd 84521: fstdx %fr4, 0(%r26)
89206491
GM
846 copy %r0, %r28
847#endif
848
849cas2_end:
850 /* Free lock */
851 stw,ma %r20, 0(%sr2,%r20)
852 /* Enable interrupts */
853 ssm PSW_SM_I, %r0
854 /* Return to userspace, set no error */
855 b lws_exit
856 copy %r0, %r21
857
85822:
859 /* Error occurred on load or store */
860 /* Free lock */
861 stw %r20, 0(%sr2,%r20)
862 ssm PSW_SM_I, %r0
863 ldo 1(%r0),%r28
864 b lws_exit
865 ldo -EFAULT(%r0),%r21 /* set errno */
866 nop
867 nop
868 nop
869
870 /* Exception table entries, for the load and store, return EFAULT.
871 Each of the entries must be relocated. */
872 ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 22b-linux_gateway_page)
873 ASM_EXCEPTIONTABLE_ENTRY(5b-linux_gateway_page, 22b-linux_gateway_page)
874 ASM_EXCEPTIONTABLE_ENTRY(6b-linux_gateway_page, 22b-linux_gateway_page)
875 ASM_EXCEPTIONTABLE_ENTRY(7b-linux_gateway_page, 22b-linux_gateway_page)
876 ASM_EXCEPTIONTABLE_ENTRY(8b-linux_gateway_page, 22b-linux_gateway_page)
877 ASM_EXCEPTIONTABLE_ENTRY(9b-linux_gateway_page, 22b-linux_gateway_page)
878 ASM_EXCEPTIONTABLE_ENTRY(10b-linux_gateway_page, 22b-linux_gateway_page)
879 ASM_EXCEPTIONTABLE_ENTRY(11b-linux_gateway_page, 22b-linux_gateway_page)
880 ASM_EXCEPTIONTABLE_ENTRY(13b-linux_gateway_page, 22b-linux_gateway_page)
881 ASM_EXCEPTIONTABLE_ENTRY(14b-linux_gateway_page, 22b-linux_gateway_page)
882 ASM_EXCEPTIONTABLE_ENTRY(15b-linux_gateway_page, 22b-linux_gateway_page)
883 ASM_EXCEPTIONTABLE_ENTRY(16b-linux_gateway_page, 22b-linux_gateway_page)
884 ASM_EXCEPTIONTABLE_ENTRY(17b-linux_gateway_page, 22b-linux_gateway_page)
885 ASM_EXCEPTIONTABLE_ENTRY(18b-linux_gateway_page, 22b-linux_gateway_page)
886 ASM_EXCEPTIONTABLE_ENTRY(19b-linux_gateway_page, 22b-linux_gateway_page)
887 ASM_EXCEPTIONTABLE_ENTRY(20b-linux_gateway_page, 22b-linux_gateway_page)
888#ifndef CONFIG_64BIT
889 ASM_EXCEPTIONTABLE_ENTRY(12b-linux_gateway_page, 22b-linux_gateway_page)
890 ASM_EXCEPTIONTABLE_ENTRY(21b-linux_gateway_page, 22b-linux_gateway_page)
891#endif
892
1da177e4 893 /* Make sure nothing else is placed on this page */
1c593571 894 .align PAGE_SIZE
8e9e9844
HD
895END(linux_gateway_page)
896ENTRY(end_linux_gateway_page)
1da177e4
LT
897
898 /* Relocate symbols assuming linux_gateway_page is mapped
899 to virtual address 0x0 */
8e9e9844 900
0b3d643f 901#define LWS_ENTRY(_name_) ASM_ULONG_INSN (lws_##_name_ - linux_gateway_page)
1da177e4 902
1bcdd854
HD
903 .section .rodata,"a"
904
6a45716a 905 .align 8
1da177e4
LT
906 /* Light-weight-syscall table */
907 /* Start of lws table. */
8e9e9844 908ENTRY(lws_table)
89206491
GM
909 LWS_ENTRY(compare_and_swap32) /* 0 - ELF32 Atomic 32bit CAS */
910 LWS_ENTRY(compare_and_swap64) /* 1 - ELF64 Atomic 32bit CAS */
911 LWS_ENTRY(compare_and_swap_2) /* 2 - ELF32 Atomic 64bit CAS */
8e9e9844 912END(lws_table)
1da177e4
LT
913 /* End of lws table */
914
6a45716a 915 .align 8
8e9e9844 916ENTRY(sys_call_table)
fc79168a 917 .export sys_call_table,data
1da177e4 918#include "syscall_table.S"
8e9e9844 919END(sys_call_table)
1da177e4 920
413059f2 921#ifdef CONFIG_64BIT
6a45716a 922 .align 8
8e9e9844 923ENTRY(sys_call_table64)
1da177e4
LT
924#define SYSCALL_TABLE_64BIT
925#include "syscall_table.S"
8e9e9844 926END(sys_call_table64)
1da177e4
LT
927#endif
928
1da177e4
LT
929 /*
930 All light-weight-syscall atomic operations
931 will use this set of locks
c84c3a69
HD
932
933 NOTE: The lws_lock_start symbol must be
934 at least 16-byte aligned for safe use
935 with ldcw.
1da177e4 936 */
dfcf753b 937 .section .data
6a45716a 938 .align L1_CACHE_BYTES
8e9e9844 939ENTRY(lws_lock_start)
1da177e4 940 /* lws locks */
1da177e4
LT
941 .rept 16
942 /* Keep locks aligned at 16-bytes */
943 .word 1
944 .word 0
945 .word 0
946 .word 0
947 .endr
8e9e9844 948END(lws_lock_start)
1da177e4 949 .previous
1da177e4
LT
950
951.end
952
953