2 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
4 * System call entry code / Linux gateway page
5 * Copyright (c) Matthew Wilcox 1999 <willy@bofh.ai>
6 * Licensed under the GNU GPL.
7 * thanks to Philipp Rumpf, Mike Shaver and various others
8 * sorry about the wall, puffin..
12 How does the Linux gateway page on PA-RISC work?
13 ------------------------------------------------
14 The Linux gateway page on PA-RISC is "special".
15 It actually has PAGE_GATEWAY bits set (this is linux terminology; in parisc
16 terminology it's Execute, promote to PL0) in the page map. So anything
17 executing on this page executes with kernel level privilege (there's more to it
18 than that: to have this happen, you also have to use a branch with a ,gate
19 completer to activate the privilege promotion). The upshot is that everything
20 that runs on the gateway page runs at kernel privilege but with the current
21 user process address space (although you have access to kernel space via %sr2).
22 For the 0x100 syscall entry, we redo the space registers to point to the kernel
23 address space (preserving the user address space in %sr3), move to wide mode if
24 required, save the user registers and branch into the kernel syscall entry
25 point. For all the other functions, we execute at kernel privilege but don't
26 flip address spaces. The basic upshot of this is that these code snippets are
27 executed atomically (because the kernel can't be pre-empted) and they may
28 perform architecturally forbidden (to PL3) operations (like setting control
33 #include <asm/asm-offsets.h>
34 #include <asm/unistd.h>
35 #include <asm/errno.h>
38 #include <asm/thread_info.h>
39 #include <asm/assembly.h>
40 #include <asm/processor.h>
41 #include <asm/cache.h>
43 #include <linux/linkage.h>
45 /* We fill the empty parts of the gateway page with
46 * something that will kill the kernel or a
47 * userspace application.
49 #define KILL_INSN break 0,0
55 .import syscall_exit,code
56 .import syscall_exit_rfi,code
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
67 ENTRY(linux_gateway_page)
69 /* ADDRESS 0x00 to 0xb0 = 176 bytes / 4 bytes per insn = 44 insns */
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)
80 gate lws_start, %r0 /* increase privilege */
81 depi 3, 31, 2, %r31 /* Ensure we return into user mode. */
83 /* Fill from 0xb8 to 0xe0 */
88 /* This function MUST be located at 0xe0 for glibc's threading
89 mechanism to work. DO NOT MOVE THIS CODE EVER! */
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 */
96 /* Increase the chance of trapping if random jumps occur to this
97 address, fill from 0xf0 to 0x100 */
102 /* This address must remain fixed at 0x100 for glibc's syscalls to work */
103 .align LINUX_GATEWAY_ADDR
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 */
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
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 */
123 /* The top halves of argument registers must be cleared on syscall
124 * entry from narrow executable.
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
135 /* We use a rsm/ssm pair to prevent sr3 from being clobbered
136 * by external interrupts.
138 mfsp %sr7,%r1 /* save user sr7 */
139 rsm PSW_SM_I, %r0 /* disable interrupts */
140 mtsp %r1,%sr3 /* and store it in sr3 */
143 xor %r1,%r30,%r30 /* ye olde xor trick */
147 ldo THREAD_SZ_ALGN+FRAME_SIZE(%r30),%r30 /* set up kernel stack */
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.
155 mtsp %r0,%sr7 /* get kernel space into sr7 */
156 ssm PSW_SM_I, %r0 /* enable interrupts */
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
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)
170 LDREGM -FRAME_SIZE(%r30), %r2 /* get users sp back */
172 extrd,u %r2,63,1,%r19 /* W hidden in bottom bit */
174 xor %r19,%r2,%r2 /* clear bottom bit */
176 std %r19,TASK_PT_PSW(%r1)
179 STREG %r2, TASK_PT_GR30(%r1) /* ... and save it */
181 STREG %r20, TASK_PT_GR20(%r1) /* Syscall number */
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 */
190 STREG %r0, TASK_PT_ORIG_R28(%r1) /* don't prohibit restarts */
191 STREG %r29, TASK_PT_GR29(%r1) /* return value 1 */
192 STREG %r31, TASK_PT_GR31(%r1) /* preserve syscall return ptr */
194 ldo TASK_PT_FR0(%r1), %r27 /* save fpregs from the kernel */
195 save_fp %r27 /* or potential task switch */
197 mfctl %cr11, %r27 /* i.e. SAR */
198 STREG %r27, TASK_PT_SAR(%r1)
203 ldo -16(%r30),%r29 /* Reference param save area */
204 copy %r19,%r2 /* W bit back to r2 */
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 */
212 /* Are we being ptraced? */
214 LDREG TI_FLAGS(%r1),%r1
215 ldi _TIF_SYSCALL_TRACE_MASK, %r19
216 and,COND(=) %r1, %r19, %r0
219 /* Note! We cannot use the syscall table that is mapped
220 nearby since the gateway page is mapped execute-only. */
223 ldil L%sys_call_table, %r1
225 addil L%(sys_call_table64-sys_call_table), %r1
226 ldo R%sys_call_table(%r1), %r19
228 ldo R%sys_call_table64(%r1), %r19
230 ldil L%sys_call_table, %r1
231 ldo R%sys_call_table(%r1), %r19
233 comiclr,>> __NR_Linux_syscalls, %r20, %r0
236 LDREGX %r20(%r19), %r19
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).
243 ldi __NR_rt_sigreturn,%r2
244 comb,= %r2,%r20,.Lrt_sigreturn
246 ldil L%syscall_exit,%r2
248 ldo R%syscall_exit(%r2),%r2
250 comib,<> 0,%r25,.Lin_syscall
251 ldil L%syscall_exit_rfi,%r2
253 ldo R%syscall_exit_rfi(%r2),%r2
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. */
262 ldil L%syscall_exit,%r1
263 be R%syscall_exit(%sr7,%r1)
264 ldo -ENOSYS(%r0),%r28 /* set errno */
267 /* Warning! This trace code is a virtual duplicate of the code above so be
268 * sure to maintain both! */
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
280 ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
281 LDREG TI_TASK(%r1), %r1
283 STREG %r2,TASK_PT_PSW(%r1) /* Lower 8 bits only!! */
285 STREG %r2,TASK_PT_SR0(%r1)
287 STREG %r2,TASK_PT_SR1(%r1)
289 STREG %r2,TASK_PT_SR2(%r1)
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)
301 STREG %r2,TASK_PT_IAOQ1(%r1)
302 ldo TASK_REGS(%r1),%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 */
323 ldil L%do_syscall_trace_enter,%r1
324 ldil L%tracesys_next,%r2
325 be R%do_syscall_trace_enter(%sr7,%r1)
326 ldo R%tracesys_next(%r2),%r2
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.
334 ldil L%sys_call_table,%r1
335 ldo R%sys_call_table(%r1), %r19
337 ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
338 LDREG TI_TASK(%r1), %r1
339 LDREG TASK_PT_GR28(%r1), %r28 /* Restore return value */
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
344 LDREG TASK_PT_GR22(%r1), %r22
345 LDREG TASK_PT_GR21(%r1), %r21
347 ldo -16(%r30),%r29 /* Reference param save area */
349 stw %r22, -52(%r30) /* 5th argument */
350 stw %r21, -56(%r30) /* 6th argument */
353 cmpib,COND(=),n -1,%r20,tracesys_exit /* seccomp may have returned -1 */
354 comiclr,>> __NR_Linux_syscalls, %r20, %r0
357 LDREGX %r20(%r19), %r19
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).
364 ldi __NR_rt_sigreturn,%r2
365 comb,= %r2,%r20,.Ltrace_rt_sigreturn
367 ldil L%tracesys_exit,%r2
369 ldo R%tracesys_exit(%r2),%r2
372 ldo -ENOSYS(%r0),%r28 /* set errno */
374 /* Do *not* call this function on the gateway page, because it
375 makes a direct call to syscall_trace. */
378 ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
379 LDREG TI_TASK(%r1), %r1
381 ldo -16(%r30),%r29 /* Reference param save area */
383 ldo TASK_REGS(%r1),%r26
384 BL do_syscall_trace_exit,%r2
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. */
390 ldil L%syscall_exit,%r1
391 be,n R%syscall_exit(%sr7,%r1)
393 .Ltrace_rt_sigreturn:
394 comib,<> 0,%r25,.Ltrace_in_syscall
395 ldil L%tracesys_sigexit,%r2
397 ldo R%tracesys_sigexit(%r2),%r2
400 ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
401 LDREG TI_TASK(%r1), %r1
403 ldo -16(%r30),%r29 /* Reference param save area */
405 BL do_syscall_trace_exit,%r2
406 ldo TASK_REGS(%r1),%r26
408 ldil L%syscall_exit_rfi,%r1
409 be,n R%syscall_exit_rfi(%sr7,%r1)
412 /*********************************************************
413 32/64-bit Light-Weight-Syscall ABI
415 * - Indicates a hint for userspace inline asm
418 Syscall number (caller-saves)
422 Argument registers (caller-saves)
423 - %r26, %r25, %r24, %r23, %r22
426 Return registers (caller-saves)
427 - %r28 (return), %r21 (errno)
430 Caller-saves registers
432 - %r2 (return pointer)
433 - %r31 (ble link register)
436 Callee-saves registers
438 - %r30 (stack pointer)
439 * Not in asm clobber.
441 If userspace is 32-bit:
442 Callee-saves registers
443 - %r19 (32-bit PIC register)
445 Differences from 32-bit calling convention:
446 - Syscall number in %r20
447 - Additional argument register %r22 (arg4)
450 If userspace is 64-bit:
451 Callee-saves registers
452 - %r27 (64-bit PIC register)
454 Differences from 64-bit calling convention:
455 - Syscall number in %r20
456 - Additional argument register %r22 (arg4)
459 Error codes returned by entry path:
461 ENOSYS - r20 was an invalid LWS number.
463 *********************************************************/
467 /* FIXME: If we are a 64-bit kernel just
468 * turn this on unconditionally.
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 */
476 /* Clip LWS number to a 32-bit value always */
477 depdi 0, 31, 32, %r20
480 /* Is the lws entry number valid? */
481 comiclr,>> __NR_lws_entries, %r20, %r0
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 */
489 /* Jump to lws, lws table pointers already relocated */
493 ldo -ENOSYS(%r0),%r21 /* set errno */
494 /* Fall through: Return to userspace */
498 /* decide whether to reset the wide mode bit
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
504 /* now reset the lowest bit of sp if it was set */
511 /***************************************************
512 Implementing 32bit CAS as an atomic operation:
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
520 If debugging is DISabled:
522 %r21 has the following meanings:
524 EAGAIN - CAS is busy, ldcw failed, try again.
525 EFAULT - Read or write failed.
527 If debugging is enabled:
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.
534 Scratch: r20, r28, r1
536 ****************************************************/
538 /* Do not enable LWS debugging */
539 #define ENABLE_LWS_DEBUG 0
541 /* ELF64 Process entry path */
542 lws_compare_and_swap64:
544 b,n lws_compare_and_swap
546 /* If we are not a 64-bit kernel, then we don't
547 * have 64-bit input registers, and calling
548 * the 64-bit LWS CAS returns ENOSYS.
553 /* ELF32 Process entry path */
554 lws_compare_and_swap32:
556 /* Clip all the input registers */
557 depdi 0, 31, 32, %r26
558 depdi 0, 31, 32, %r25
559 depdi 0, 31, 32, %r24
562 lws_compare_and_swap:
563 /* Load start of lock table */
564 ldil L%lws_lock_start, %r20
565 ldo R%lws_lock_start(%r20), %r28
567 /* Extract four bits from r26 and hash lock (Bits 4-7) */
568 extru %r26, 27, 4, %r20
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. */
576 # if ENABLE_LWS_DEBUG
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.
584 ldw 4(%sr2,%r20), %r28 /* Load thread register */
585 /* WARNING: If cr27 cycles to the same value we have problems */
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
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 */
597 /* ENABLE_LWS_DEBUG */
599 rsm PSW_SM_I, %r0 /* Disable interrupts */
600 /* COW breaks can cause contention on UP systems */
601 LDCW 0(%sr2,%r20), %r28 /* Try to acquire the lock */
602 cmpb,<>,n %r0, %r28, cas_action /* Did we get it? */
604 ldo 2(%r0), %r28 /* 2nd case */
606 b lws_exit /* Contended... */
607 ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
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
626 #if defined CONFIG_SMP && ENABLE_LWS_DEBUG
629 stw %r1, 4(%sr2,%r20)
631 /* The load and store could fail */
633 sub,<> %r28, %r25, %r0
637 stw %r20, 0(%sr2,%r20)
639 /* Clear thread register indicator */
640 stw %r0, 4(%sr2,%r20)
642 /* Enable interrupts */
644 /* Return to userspace, set no error */
649 /* Error occurred on load or store */
652 stw %r20, 0(%sr2,%r20)
654 stw %r0, 4(%sr2,%r20)
658 ldo -EFAULT(%r0),%r21 /* set errno */
664 /* Two exception table entries, one for the load,
665 the other for the store. Either return -EFAULT.
666 Each of the entries must be relocated. */
667 ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 3b-linux_gateway_page)
668 ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 3b-linux_gateway_page)
671 /***************************************************
672 New CAS implementation which uses pointers and variable size
673 information. The value pointed by old and new MUST NOT change
674 while performing CAS. The lock only protect the value at %r26.
676 %r26 - Address to examine
677 %r25 - Pointer to the value to check (old)
678 %r24 - Pointer to the value to set (new)
679 %r23 - Size of the variable (0/1/2/3 for 8/16/32/64 bit)
680 %r28 - Return non-zero on failure
681 %r21 - Kernel error code
683 %r21 has the following meanings:
685 EAGAIN - CAS is busy, ldcw failed, try again.
686 EFAULT - Read or write failed.
688 Scratch: r20, r22, r28, r29, r1, fr4 (32bit for 64bit CAS only)
690 ****************************************************/
692 /* ELF32 Process entry path */
693 lws_compare_and_swap_2:
695 /* Clip the input registers. We don't need to clip %r23 as we
696 only use it for word operations */
697 depdi 0, 31, 32, %r26
698 depdi 0, 31, 32, %r25
699 depdi 0, 31, 32, %r24
702 /* Check the validity of the size pointer */
703 subi,>>= 3, %r23, %r0
706 /* Jump to the functions which will load the old and new values into
707 registers depending on the their size */
744 10: ldd 0(%r25), %r25
745 11: ldd 0(%r24), %r24
747 /* Load old value into r22/r23 - high/low */
748 10: ldw 0(%r25), %r22
749 11: ldw 4(%r25), %r23
750 /* Load new value into fr4 for atomic store later */
751 12: flddx 0(%r24), %fr4
755 /* Load start of lock table */
756 ldil L%lws_lock_start, %r20
757 ldo R%lws_lock_start(%r20), %r28
759 /* Extract four bits from r26 and hash lock (Bits 4-7) */
760 extru %r26, 27, 4, %r20
762 /* Find lock to use, the hash is either one of 0 to
763 15, multiplied by 16 (keep it 16-byte aligned)
764 and add to the lock table offset. */
768 rsm PSW_SM_I, %r0 /* Disable interrupts */
769 /* COW breaks can cause contention on UP systems */
770 LDCW 0(%sr2,%r20), %r28 /* Try to acquire the lock */
771 cmpb,<>,n %r0, %r28, cas2_action /* Did we get it? */
773 ldo 2(%r0), %r28 /* 2nd case */
775 b lws_exit /* Contended... */
776 ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
786 This all works becuse intr_do_signal
787 and schedule both check the return iasq
788 and see that we are on the kernel page
789 so this process is never scheduled off
790 or is ever sent any signal of any sort,
791 thus it is wholly atomic from usrspaces
795 /* Jump to the correct function */
797 /* Set %r28 as non-zero for now */
801 13: ldb 0(%r26), %r29
802 sub,= %r29, %r25, %r0
804 14: stb %r24, 0(%r26)
811 15: ldh 0(%r26), %r29
812 sub,= %r29, %r25, %r0
814 16: sth %r24, 0(%r26)
821 17: ldw 0(%r26), %r29
822 sub,= %r29, %r25, %r0
824 18: stw %r24, 0(%r26)
832 19: ldd 0(%r26), %r29
833 sub,*= %r29, %r25, %r0
835 20: std %r24, 0(%r26)
838 /* Compare first word */
839 19: ldw 0(%r26), %r29
840 sub,= %r29, %r22, %r0
842 /* Compare second word */
843 20: ldw 4(%r26), %r29
844 sub,= %r29, %r23, %r0
846 /* Perform the store */
847 21: fstdx %fr4, 0(%r26)
854 stw %r20, 0(%sr2,%r20)
855 /* Enable interrupts */
857 /* Return to userspace, set no error */
862 /* Error occurred on load or store */
865 stw %r20, 0(%sr2,%r20)
869 ldo -EFAULT(%r0),%r21 /* set errno */
874 /* Exception table entries, for the load and store, return EFAULT.
875 Each of the entries must be relocated. */
876 ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 22b-linux_gateway_page)
877 ASM_EXCEPTIONTABLE_ENTRY(5b-linux_gateway_page, 22b-linux_gateway_page)
878 ASM_EXCEPTIONTABLE_ENTRY(6b-linux_gateway_page, 22b-linux_gateway_page)
879 ASM_EXCEPTIONTABLE_ENTRY(7b-linux_gateway_page, 22b-linux_gateway_page)
880 ASM_EXCEPTIONTABLE_ENTRY(8b-linux_gateway_page, 22b-linux_gateway_page)
881 ASM_EXCEPTIONTABLE_ENTRY(9b-linux_gateway_page, 22b-linux_gateway_page)
882 ASM_EXCEPTIONTABLE_ENTRY(10b-linux_gateway_page, 22b-linux_gateway_page)
883 ASM_EXCEPTIONTABLE_ENTRY(11b-linux_gateway_page, 22b-linux_gateway_page)
884 ASM_EXCEPTIONTABLE_ENTRY(13b-linux_gateway_page, 22b-linux_gateway_page)
885 ASM_EXCEPTIONTABLE_ENTRY(14b-linux_gateway_page, 22b-linux_gateway_page)
886 ASM_EXCEPTIONTABLE_ENTRY(15b-linux_gateway_page, 22b-linux_gateway_page)
887 ASM_EXCEPTIONTABLE_ENTRY(16b-linux_gateway_page, 22b-linux_gateway_page)
888 ASM_EXCEPTIONTABLE_ENTRY(17b-linux_gateway_page, 22b-linux_gateway_page)
889 ASM_EXCEPTIONTABLE_ENTRY(18b-linux_gateway_page, 22b-linux_gateway_page)
890 ASM_EXCEPTIONTABLE_ENTRY(19b-linux_gateway_page, 22b-linux_gateway_page)
891 ASM_EXCEPTIONTABLE_ENTRY(20b-linux_gateway_page, 22b-linux_gateway_page)
893 ASM_EXCEPTIONTABLE_ENTRY(12b-linux_gateway_page, 22b-linux_gateway_page)
894 ASM_EXCEPTIONTABLE_ENTRY(21b-linux_gateway_page, 22b-linux_gateway_page)
897 /* Make sure nothing else is placed on this page */
899 END(linux_gateway_page)
900 ENTRY(end_linux_gateway_page)
902 /* Relocate symbols assuming linux_gateway_page is mapped
903 to virtual address 0x0 */
905 #define LWS_ENTRY(_name_) ASM_ULONG_INSN (lws_##_name_ - linux_gateway_page)
910 /* Light-weight-syscall table */
911 /* Start of lws table. */
913 LWS_ENTRY(compare_and_swap32) /* 0 - ELF32 Atomic 32bit CAS */
914 LWS_ENTRY(compare_and_swap64) /* 1 - ELF64 Atomic 32bit CAS */
915 LWS_ENTRY(compare_and_swap_2) /* 2 - ELF32 Atomic 64bit CAS */
917 /* End of lws table */
920 ENTRY(sys_call_table)
921 .export sys_call_table,data
922 #include "syscall_table.S"
927 ENTRY(sys_call_table64)
928 #define SYSCALL_TABLE_64BIT
929 #include "syscall_table.S"
930 END(sys_call_table64)
934 All light-weight-syscall atomic operations
935 will use this set of locks
937 NOTE: The lws_lock_start symbol must be
938 at least 16-byte aligned for safe use
942 .align L1_CACHE_BYTES
943 ENTRY(lws_lock_start)
946 /* Keep locks aligned at 16-bytes */