syscall.S 19 KB

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  1. /*
  2. * Linux/PA-RISC Project (http://www.parisc-linux.org/)
  3. *
  4. * System call entry code Copyright (c) Matthew Wilcox 1999 <willy@bofh.ai>
  5. * Licensed under the GNU GPL.
  6. * thanks to Philipp Rumpf, Mike Shaver and various others
  7. * sorry about the wall, puffin..
  8. */
  9. #include <asm/asm-offsets.h>
  10. #include <asm/unistd.h>
  11. #include <asm/errno.h>
  12. #include <asm/page.h>
  13. #include <asm/psw.h>
  14. #include <asm/thread_info.h>
  15. #include <asm/assembly.h>
  16. #include <asm/processor.h>
  17. #include <linux/linkage.h>
  18. /* We fill the empty parts of the gateway page with
  19. * something that will kill the kernel or a
  20. * userspace application.
  21. */
  22. #define KILL_INSN break 0,0
  23. .level LEVEL
  24. .text
  25. .import syscall_exit,code
  26. .import syscall_exit_rfi,code
  27. /* Linux gateway page is aliased to virtual page 0 in the kernel
  28. * address space. Since it is a gateway page it cannot be
  29. * dereferenced, so null pointers will still fault. We start
  30. * the actual entry point at 0x100. We put break instructions
  31. * at the beginning of the page to trap null indirect function
  32. * pointers.
  33. */
  34. .align PAGE_SIZE
  35. ENTRY(linux_gateway_page)
  36. /* ADDRESS 0x00 to 0xb0 = 176 bytes / 4 bytes per insn = 44 insns */
  37. .rept 44
  38. KILL_INSN
  39. .endr
  40. /* ADDRESS 0xb0 to 0xb8, lws uses two insns for entry */
  41. /* Light-weight-syscall entry must always be located at 0xb0 */
  42. /* WARNING: Keep this number updated with table size changes */
  43. #define __NR_lws_entries (2)
  44. lws_entry:
  45. gate lws_start, %r0 /* increase privilege */
  46. depi 3, 31, 2, %r31 /* Ensure we return into user mode. */
  47. /* Fill from 0xb8 to 0xe0 */
  48. .rept 10
  49. KILL_INSN
  50. .endr
  51. /* This function MUST be located at 0xe0 for glibc's threading
  52. mechanism to work. DO NOT MOVE THIS CODE EVER! */
  53. set_thread_pointer:
  54. gate .+8, %r0 /* increase privilege */
  55. depi 3, 31, 2, %r31 /* Ensure we return into user mode. */
  56. be 0(%sr7,%r31) /* return to user space */
  57. mtctl %r26, %cr27 /* move arg0 to the control register */
  58. /* Increase the chance of trapping if random jumps occur to this
  59. address, fill from 0xf0 to 0x100 */
  60. .rept 4
  61. KILL_INSN
  62. .endr
  63. /* This address must remain fixed at 0x100 for glibc's syscalls to work */
  64. .align 256
  65. linux_gateway_entry:
  66. gate .+8, %r0 /* become privileged */
  67. mtsp %r0,%sr4 /* get kernel space into sr4 */
  68. mtsp %r0,%sr5 /* get kernel space into sr5 */
  69. mtsp %r0,%sr6 /* get kernel space into sr6 */
  70. mfsp %sr7,%r1 /* save user sr7 */
  71. mtsp %r1,%sr3 /* and store it in sr3 */
  72. #ifdef CONFIG_64BIT
  73. /* for now we can *always* set the W bit on entry to the syscall
  74. * since we don't support wide userland processes. We could
  75. * also save the current SM other than in r0 and restore it on
  76. * exit from the syscall, and also use that value to know
  77. * whether to do narrow or wide syscalls. -PB
  78. */
  79. ssm PSW_SM_W, %r1
  80. extrd,u %r1,PSW_W_BIT,1,%r1
  81. /* sp must be aligned on 4, so deposit the W bit setting into
  82. * the bottom of sp temporarily */
  83. or,ev %r1,%r30,%r30
  84. b,n 1f
  85. /* The top halves of argument registers must be cleared on syscall
  86. * entry from narrow executable.
  87. */
  88. depdi 0, 31, 32, %r26
  89. depdi 0, 31, 32, %r25
  90. depdi 0, 31, 32, %r24
  91. depdi 0, 31, 32, %r23
  92. depdi 0, 31, 32, %r22
  93. depdi 0, 31, 32, %r21
  94. 1:
  95. #endif
  96. mfctl %cr30,%r1
  97. xor %r1,%r30,%r30 /* ye olde xor trick */
  98. xor %r1,%r30,%r1
  99. xor %r1,%r30,%r30
  100. ldo THREAD_SZ_ALGN+FRAME_SIZE(%r30),%r30 /* set up kernel stack */
  101. /* N.B.: It is critical that we don't set sr7 to 0 until r30
  102. * contains a valid kernel stack pointer. It is also
  103. * critical that we don't start using the kernel stack
  104. * until after sr7 has been set to 0.
  105. */
  106. mtsp %r0,%sr7 /* get kernel space into sr7 */
  107. STREGM %r1,FRAME_SIZE(%r30) /* save r1 (usp) here for now */
  108. mfctl %cr30,%r1 /* get task ptr in %r1 */
  109. LDREG TI_TASK(%r1),%r1
  110. /* Save some registers for sigcontext and potential task
  111. switch (see entry.S for the details of which ones are
  112. saved/restored). TASK_PT_PSW is zeroed so we can see whether
  113. a process is on a syscall or not. For an interrupt the real
  114. PSW value is stored. This is needed for gdb and sys_ptrace. */
  115. STREG %r0, TASK_PT_PSW(%r1)
  116. STREG %r2, TASK_PT_GR2(%r1) /* preserve rp */
  117. STREG %r19, TASK_PT_GR19(%r1)
  118. LDREGM -FRAME_SIZE(%r30), %r2 /* get users sp back */
  119. #ifdef CONFIG_64BIT
  120. extrd,u %r2,63,1,%r19 /* W hidden in bottom bit */
  121. #if 0
  122. xor %r19,%r2,%r2 /* clear bottom bit */
  123. depd,z %r19,1,1,%r19
  124. std %r19,TASK_PT_PSW(%r1)
  125. #endif
  126. #endif
  127. STREG %r2, TASK_PT_GR30(%r1) /* ... and save it */
  128. STREG %r20, TASK_PT_GR20(%r1) /* Syscall number */
  129. STREG %r21, TASK_PT_GR21(%r1)
  130. STREG %r22, TASK_PT_GR22(%r1)
  131. STREG %r23, TASK_PT_GR23(%r1) /* 4th argument */
  132. STREG %r24, TASK_PT_GR24(%r1) /* 3rd argument */
  133. STREG %r25, TASK_PT_GR25(%r1) /* 2nd argument */
  134. STREG %r26, TASK_PT_GR26(%r1) /* 1st argument */
  135. STREG %r27, TASK_PT_GR27(%r1) /* user dp */
  136. STREG %r28, TASK_PT_GR28(%r1) /* return value 0 */
  137. STREG %r28, TASK_PT_ORIG_R28(%r1) /* return value 0 (saved for signals) */
  138. STREG %r29, TASK_PT_GR29(%r1) /* return value 1 */
  139. STREG %r31, TASK_PT_GR31(%r1) /* preserve syscall return ptr */
  140. ldo TASK_PT_FR0(%r1), %r27 /* save fpregs from the kernel */
  141. save_fp %r27 /* or potential task switch */
  142. mfctl %cr11, %r27 /* i.e. SAR */
  143. STREG %r27, TASK_PT_SAR(%r1)
  144. loadgp
  145. #ifdef CONFIG_64BIT
  146. ldo -16(%r30),%r29 /* Reference param save area */
  147. copy %r19,%r2 /* W bit back to r2 */
  148. #else
  149. /* no need to save these on stack in wide mode because the first 8
  150. * args are passed in registers */
  151. stw %r22, -52(%r30) /* 5th argument */
  152. stw %r21, -56(%r30) /* 6th argument */
  153. #endif
  154. /* Are we being ptraced? */
  155. mfctl %cr30, %r1
  156. LDREG TI_TASK(%r1),%r1
  157. ldw TASK_PTRACE(%r1), %r1
  158. bb,<,n %r1,31,.Ltracesys
  159. /* Note! We cannot use the syscall table that is mapped
  160. nearby since the gateway page is mapped execute-only. */
  161. #ifdef CONFIG_64BIT
  162. ldil L%sys_call_table, %r1
  163. or,= %r2,%r2,%r2
  164. addil L%(sys_call_table64-sys_call_table), %r1
  165. ldo R%sys_call_table(%r1), %r19
  166. or,= %r2,%r2,%r2
  167. ldo R%sys_call_table64(%r1), %r19
  168. #else
  169. ldil L%sys_call_table, %r1
  170. ldo R%sys_call_table(%r1), %r19
  171. #endif
  172. comiclr,>> __NR_Linux_syscalls, %r20, %r0
  173. b,n .Lsyscall_nosys
  174. LDREGX %r20(%r19), %r19
  175. /* If this is a sys_rt_sigreturn call, and the signal was received
  176. * when not in_syscall, then we want to return via syscall_exit_rfi,
  177. * not syscall_exit. Signal no. in r20, in_syscall in r25 (see
  178. * trampoline code in signal.c).
  179. */
  180. ldi __NR_rt_sigreturn,%r2
  181. comb,= %r2,%r20,.Lrt_sigreturn
  182. .Lin_syscall:
  183. ldil L%syscall_exit,%r2
  184. be 0(%sr7,%r19)
  185. ldo R%syscall_exit(%r2),%r2
  186. .Lrt_sigreturn:
  187. comib,<> 0,%r25,.Lin_syscall
  188. ldil L%syscall_exit_rfi,%r2
  189. be 0(%sr7,%r19)
  190. ldo R%syscall_exit_rfi(%r2),%r2
  191. /* Note! Because we are not running where we were linked, any
  192. calls to functions external to this file must be indirect. To
  193. be safe, we apply the opposite rule to functions within this
  194. file, with local labels given to them to ensure correctness. */
  195. .Lsyscall_nosys:
  196. syscall_nosys:
  197. ldil L%syscall_exit,%r1
  198. be R%syscall_exit(%sr7,%r1)
  199. ldo -ENOSYS(%r0),%r28 /* set errno */
  200. /* Warning! This trace code is a virtual duplicate of the code above so be
  201. * sure to maintain both! */
  202. .Ltracesys:
  203. tracesys:
  204. /* Need to save more registers so the debugger can see where we
  205. * are. This saves only the lower 8 bits of PSW, so that the C
  206. * bit is still clear on syscalls, and the D bit is set if this
  207. * full register save path has been executed. We check the D
  208. * bit on syscall_return_rfi to determine which registers to
  209. * restore. An interrupt results in a full PSW saved with the
  210. * C bit set, a non-straced syscall entry results in C and D clear
  211. * in the saved PSW.
  212. */
  213. ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
  214. LDREG TI_TASK(%r1), %r1
  215. ssm 0,%r2
  216. STREG %r2,TASK_PT_PSW(%r1) /* Lower 8 bits only!! */
  217. mfsp %sr0,%r2
  218. STREG %r2,TASK_PT_SR0(%r1)
  219. mfsp %sr1,%r2
  220. STREG %r2,TASK_PT_SR1(%r1)
  221. mfsp %sr2,%r2
  222. STREG %r2,TASK_PT_SR2(%r1)
  223. mfsp %sr3,%r2
  224. STREG %r2,TASK_PT_SR3(%r1)
  225. STREG %r2,TASK_PT_SR4(%r1)
  226. STREG %r2,TASK_PT_SR5(%r1)
  227. STREG %r2,TASK_PT_SR6(%r1)
  228. STREG %r2,TASK_PT_SR7(%r1)
  229. STREG %r2,TASK_PT_IASQ0(%r1)
  230. STREG %r2,TASK_PT_IASQ1(%r1)
  231. LDREG TASK_PT_GR31(%r1),%r2
  232. STREG %r2,TASK_PT_IAOQ0(%r1)
  233. ldo 4(%r2),%r2
  234. STREG %r2,TASK_PT_IAOQ1(%r1)
  235. ldo TASK_REGS(%r1),%r2
  236. /* reg_save %r2 */
  237. STREG %r3,PT_GR3(%r2)
  238. STREG %r4,PT_GR4(%r2)
  239. STREG %r5,PT_GR5(%r2)
  240. STREG %r6,PT_GR6(%r2)
  241. STREG %r7,PT_GR7(%r2)
  242. STREG %r8,PT_GR8(%r2)
  243. STREG %r9,PT_GR9(%r2)
  244. STREG %r10,PT_GR10(%r2)
  245. STREG %r11,PT_GR11(%r2)
  246. STREG %r12,PT_GR12(%r2)
  247. STREG %r13,PT_GR13(%r2)
  248. STREG %r14,PT_GR14(%r2)
  249. STREG %r15,PT_GR15(%r2)
  250. STREG %r16,PT_GR16(%r2)
  251. STREG %r17,PT_GR17(%r2)
  252. STREG %r18,PT_GR18(%r2)
  253. /* Finished saving things for the debugger */
  254. copy %r2,%r26
  255. ldil L%do_syscall_trace_enter,%r1
  256. ldil L%tracesys_next,%r2
  257. be R%do_syscall_trace_enter(%sr7,%r1)
  258. ldo R%tracesys_next(%r2),%r2
  259. tracesys_next:
  260. /* do_syscall_trace_enter either returned the syscallno, or -1L,
  261. * so we skip restoring the PT_GR20 below, since we pulled it from
  262. * task->thread.regs.gr[20] above.
  263. */
  264. copy %ret0,%r20
  265. ldil L%sys_call_table,%r1
  266. ldo R%sys_call_table(%r1), %r19
  267. ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
  268. LDREG TI_TASK(%r1), %r1
  269. LDREG TASK_PT_GR26(%r1), %r26 /* Restore the users args */
  270. LDREG TASK_PT_GR25(%r1), %r25
  271. LDREG TASK_PT_GR24(%r1), %r24
  272. LDREG TASK_PT_GR23(%r1), %r23
  273. #ifdef CONFIG_64BIT
  274. LDREG TASK_PT_GR22(%r1), %r22
  275. LDREG TASK_PT_GR21(%r1), %r21
  276. ldo -16(%r30),%r29 /* Reference param save area */
  277. #endif
  278. comiclr,>>= __NR_Linux_syscalls, %r20, %r0
  279. b,n .Lsyscall_nosys
  280. LDREGX %r20(%r19), %r19
  281. /* If this is a sys_rt_sigreturn call, and the signal was received
  282. * when not in_syscall, then we want to return via syscall_exit_rfi,
  283. * not syscall_exit. Signal no. in r20, in_syscall in r25 (see
  284. * trampoline code in signal.c).
  285. */
  286. ldi __NR_rt_sigreturn,%r2
  287. comb,= %r2,%r20,.Ltrace_rt_sigreturn
  288. .Ltrace_in_syscall:
  289. ldil L%tracesys_exit,%r2
  290. be 0(%sr7,%r19)
  291. ldo R%tracesys_exit(%r2),%r2
  292. /* Do *not* call this function on the gateway page, because it
  293. makes a direct call to syscall_trace. */
  294. tracesys_exit:
  295. ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
  296. LDREG TI_TASK(%r1), %r1
  297. #ifdef CONFIG_64BIT
  298. ldo -16(%r30),%r29 /* Reference param save area */
  299. #endif
  300. ldo TASK_REGS(%r1),%r26
  301. bl do_syscall_trace_exit,%r2
  302. STREG %r28,TASK_PT_GR28(%r1) /* save return value now */
  303. ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
  304. LDREG TI_TASK(%r1), %r1
  305. LDREG TASK_PT_GR28(%r1), %r28 /* Restore return val. */
  306. ldil L%syscall_exit,%r1
  307. be,n R%syscall_exit(%sr7,%r1)
  308. .Ltrace_rt_sigreturn:
  309. comib,<> 0,%r25,.Ltrace_in_syscall
  310. ldil L%tracesys_sigexit,%r2
  311. be 0(%sr7,%r19)
  312. ldo R%tracesys_sigexit(%r2),%r2
  313. tracesys_sigexit:
  314. ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
  315. LDREG TI_TASK(%r1), %r1
  316. #ifdef CONFIG_64BIT
  317. ldo -16(%r30),%r29 /* Reference param save area */
  318. #endif
  319. bl do_syscall_trace_exit,%r2
  320. ldo TASK_REGS(%r1),%r26
  321. ldil L%syscall_exit_rfi,%r1
  322. be,n R%syscall_exit_rfi(%sr7,%r1)
  323. /*********************************************************
  324. 32/64-bit Light-Weight-Syscall ABI
  325. * - Indicates a hint for userspace inline asm
  326. implementations.
  327. Syscall number (caller-saves)
  328. - %r20
  329. * In asm clobber.
  330. Argument registers (caller-saves)
  331. - %r26, %r25, %r24, %r23, %r22
  332. * In asm input.
  333. Return registers (caller-saves)
  334. - %r28 (return), %r21 (errno)
  335. * In asm output.
  336. Caller-saves registers
  337. - %r1, %r27, %r29
  338. - %r2 (return pointer)
  339. - %r31 (ble link register)
  340. * In asm clobber.
  341. Callee-saves registers
  342. - %r3-%r18
  343. - %r30 (stack pointer)
  344. * Not in asm clobber.
  345. If userspace is 32-bit:
  346. Callee-saves registers
  347. - %r19 (32-bit PIC register)
  348. Differences from 32-bit calling convention:
  349. - Syscall number in %r20
  350. - Additional argument register %r22 (arg4)
  351. - Callee-saves %r19.
  352. If userspace is 64-bit:
  353. Callee-saves registers
  354. - %r27 (64-bit PIC register)
  355. Differences from 64-bit calling convention:
  356. - Syscall number in %r20
  357. - Additional argument register %r22 (arg4)
  358. - Callee-saves %r27.
  359. Error codes returned by entry path:
  360. ENOSYS - r20 was an invalid LWS number.
  361. *********************************************************/
  362. lws_start:
  363. #ifdef CONFIG_64BIT
  364. /* FIXME: If we are a 64-bit kernel just
  365. * turn this on unconditionally.
  366. */
  367. ssm PSW_SM_W, %r1
  368. extrd,u %r1,PSW_W_BIT,1,%r1
  369. /* sp must be aligned on 4, so deposit the W bit setting into
  370. * the bottom of sp temporarily */
  371. or,ev %r1,%r30,%r30
  372. /* Clip LWS number to a 32-bit value always */
  373. depdi 0, 31, 32, %r20
  374. #endif
  375. /* Is the lws entry number valid? */
  376. comiclr,>> __NR_lws_entries, %r20, %r0
  377. b,n lws_exit_nosys
  378. /* WARNING: Trashing sr2 and sr3 */
  379. mfsp %sr7,%r1 /* get userspace into sr3 */
  380. mtsp %r1,%sr3
  381. mtsp %r0,%sr2 /* get kernel space into sr2 */
  382. /* Load table start */
  383. ldil L%lws_table, %r1
  384. ldo R%lws_table(%r1), %r28 /* Scratch use of r28 */
  385. LDREGX %r20(%sr2,r28), %r21 /* Scratch use of r21 */
  386. /* Jump to lws, lws table pointers already relocated */
  387. be,n 0(%sr2,%r21)
  388. lws_exit_nosys:
  389. ldo -ENOSYS(%r0),%r21 /* set errno */
  390. /* Fall through: Return to userspace */
  391. lws_exit:
  392. #ifdef CONFIG_64BIT
  393. /* decide whether to reset the wide mode bit
  394. *
  395. * For a syscall, the W bit is stored in the lowest bit
  396. * of sp. Extract it and reset W if it is zero */
  397. extrd,u,*<> %r30,63,1,%r1
  398. rsm PSW_SM_W, %r0
  399. /* now reset the lowest bit of sp if it was set */
  400. xor %r30,%r1,%r30
  401. #endif
  402. be,n 0(%sr7, %r31)
  403. /***************************************************
  404. Implementing CAS as an atomic operation:
  405. %r26 - Address to examine
  406. %r25 - Old value to check (old)
  407. %r24 - New value to set (new)
  408. %r28 - Return prev through this register.
  409. %r21 - Kernel error code
  410. If debugging is DISabled:
  411. %r21 has the following meanings:
  412. EAGAIN - CAS is busy, ldcw failed, try again.
  413. EFAULT - Read or write failed.
  414. If debugging is enabled:
  415. EDEADLOCK - CAS called recursively.
  416. EAGAIN && r28 == 1 - CAS is busy. Lock contended.
  417. EAGAIN && r28 == 2 - CAS is busy. ldcw failed.
  418. EFAULT - Read or write failed.
  419. Scratch: r20, r28, r1
  420. ****************************************************/
  421. /* Do not enable LWS debugging */
  422. #define ENABLE_LWS_DEBUG 0
  423. /* ELF64 Process entry path */
  424. lws_compare_and_swap64:
  425. #ifdef CONFIG_64BIT
  426. b,n lws_compare_and_swap
  427. #else
  428. /* If we are not a 64-bit kernel, then we don't
  429. * have 64-bit input registers, and calling
  430. * the 64-bit LWS CAS returns ENOSYS.
  431. */
  432. b,n lws_exit_nosys
  433. #endif
  434. /* ELF32 Process entry path */
  435. lws_compare_and_swap32:
  436. #ifdef CONFIG_64BIT
  437. /* Clip all the input registers */
  438. depdi 0, 31, 32, %r26
  439. depdi 0, 31, 32, %r25
  440. depdi 0, 31, 32, %r24
  441. #endif
  442. lws_compare_and_swap:
  443. /* Load start of lock table */
  444. ldil L%lws_lock_start, %r20
  445. ldo R%lws_lock_start(%r20), %r28
  446. /* Extract four bits from r26 and hash lock (Bits 4-7) */
  447. extru %r26, 27, 4, %r20
  448. /* Find lock to use, the hash is either one of 0 to
  449. 15, multiplied by 16 (keep it 16-byte aligned)
  450. and add to the lock table offset. */
  451. shlw %r20, 4, %r20
  452. add %r20, %r28, %r20
  453. # if ENABLE_LWS_DEBUG
  454. /*
  455. DEBUG, check for deadlock!
  456. If the thread register values are the same
  457. then we were the one that locked it last and
  458. this is a recurisve call that will deadlock.
  459. We *must* giveup this call and fail.
  460. */
  461. ldw 4(%sr2,%r20), %r28 /* Load thread register */
  462. /* WARNING: If cr27 cycles to the same value we have problems */
  463. mfctl %cr27, %r21 /* Get current thread register */
  464. cmpb,<>,n %r21, %r28, cas_lock /* Called recursive? */
  465. b lws_exit /* Return error! */
  466. ldo -EDEADLOCK(%r0), %r21
  467. cas_lock:
  468. cmpb,=,n %r0, %r28, cas_nocontend /* Is nobody using it? */
  469. ldo 1(%r0), %r28 /* 1st case */
  470. b lws_exit /* Contended... */
  471. ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
  472. cas_nocontend:
  473. # endif
  474. /* ENABLE_LWS_DEBUG */
  475. LDCW 0(%sr2,%r20), %r28 /* Try to acquire the lock */
  476. cmpb,<>,n %r0, %r28, cas_action /* Did we get it? */
  477. cas_wouldblock:
  478. ldo 2(%r0), %r28 /* 2nd case */
  479. b lws_exit /* Contended... */
  480. ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
  481. /*
  482. prev = *addr;
  483. if ( prev == old )
  484. *addr = new;
  485. return prev;
  486. */
  487. /* NOTES:
  488. This all works becuse intr_do_signal
  489. and schedule both check the return iasq
  490. and see that we are on the kernel page
  491. so this process is never scheduled off
  492. or is ever sent any signal of any sort,
  493. thus it is wholly atomic from usrspaces
  494. perspective
  495. */
  496. cas_action:
  497. #if defined CONFIG_SMP && ENABLE_LWS_DEBUG
  498. /* DEBUG */
  499. mfctl %cr27, %r1
  500. stw %r1, 4(%sr2,%r20)
  501. #endif
  502. /* The load and store could fail */
  503. 1: ldw 0(%sr3,%r26), %r28
  504. sub,<> %r28, %r25, %r0
  505. 2: stw %r24, 0(%sr3,%r26)
  506. /* Free lock */
  507. stw %r20, 0(%sr2,%r20)
  508. #if ENABLE_LWS_DEBUG
  509. /* Clear thread register indicator */
  510. stw %r0, 4(%sr2,%r20)
  511. #endif
  512. /* Return to userspace, set no error */
  513. b lws_exit
  514. copy %r0, %r21
  515. 3:
  516. /* Error occurred on load or store */
  517. /* Free lock */
  518. stw %r20, 0(%sr2,%r20)
  519. #if ENABLE_LWS_DEBUG
  520. stw %r0, 4(%sr2,%r20)
  521. #endif
  522. b lws_exit
  523. ldo -EFAULT(%r0),%r21 /* set errno */
  524. nop
  525. nop
  526. nop
  527. nop
  528. /* Two exception table entries, one for the load,
  529. the other for the store. Either return -EFAULT.
  530. Each of the entries must be relocated. */
  531. .section __ex_table,"aw"
  532. ASM_ULONG_INSN (1b - linux_gateway_page), (3b - linux_gateway_page)
  533. ASM_ULONG_INSN (2b - linux_gateway_page), (3b - linux_gateway_page)
  534. .previous
  535. /* Make sure nothing else is placed on this page */
  536. .align PAGE_SIZE
  537. END(linux_gateway_page)
  538. ENTRY(end_linux_gateway_page)
  539. /* Relocate symbols assuming linux_gateway_page is mapped
  540. to virtual address 0x0 */
  541. #define LWS_ENTRY(_name_) ASM_ULONG_INSN (lws_##_name_ - linux_gateway_page)
  542. .section .rodata,"a"
  543. .align PAGE_SIZE
  544. /* Light-weight-syscall table */
  545. /* Start of lws table. */
  546. ENTRY(lws_table)
  547. LWS_ENTRY(compare_and_swap32) /* 0 - ELF32 Atomic compare and swap */
  548. LWS_ENTRY(compare_and_swap64) /* 1 - ELF64 Atomic compare and swap */
  549. END(lws_table)
  550. /* End of lws table */
  551. .align PAGE_SIZE
  552. ENTRY(sys_call_table)
  553. #include "syscall_table.S"
  554. END(sys_call_table)
  555. #ifdef CONFIG_64BIT
  556. .align PAGE_SIZE
  557. ENTRY(sys_call_table64)
  558. #define SYSCALL_TABLE_64BIT
  559. #include "syscall_table.S"
  560. END(sys_call_table64)
  561. #endif
  562. /*
  563. All light-weight-syscall atomic operations
  564. will use this set of locks
  565. NOTE: The lws_lock_start symbol must be
  566. at least 16-byte aligned for safe use
  567. with ldcw.
  568. */
  569. .section .data
  570. .align PAGE_SIZE
  571. ENTRY(lws_lock_start)
  572. /* lws locks */
  573. .rept 16
  574. /* Keep locks aligned at 16-bytes */
  575. .word 1
  576. .word 0
  577. .word 0
  578. .word 0
  579. .endr
  580. END(lws_lock_start)
  581. .previous
  582. .end