1/* 2 * linux/arch/arm/kernel/entry-common.S 3 * 4 * Copyright (C) 2000 Russell King 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10 11#include <asm/unistd.h> 12#include <asm/ftrace.h> 13#include <asm/unwind.h> 14 15#ifdef CONFIG_NEED_RET_TO_USER 16#include <mach/entry-macro.S> 17#else 18 .macro arch_ret_to_user, tmp1, tmp2 19 .endm 20#endif 21 22#include "entry-header.S" 23 24 25 .align 5 26/* 27 * This is the fast syscall return path. We do as little as 28 * possible here, and this includes saving r0 back into the SVC 29 * stack. 30 */ 31ret_fast_syscall: 32 UNWIND(.fnstart ) 33 UNWIND(.cantunwind ) 34 disable_irq @ disable interrupts 35 ldr r1, [tsk, #TI_FLAGS] 36 tst r1, #_TIF_WORK_MASK 37 bne fast_work_pending 38#if defined(CONFIG_IRQSOFF_TRACER) 39 asm_trace_hardirqs_on 40#endif 41 42 /* perform architecture specific actions before user return */ 43 arch_ret_to_user r1, lr 44 45 restore_user_regs fast = 1, offset = S_OFF 46 UNWIND(.fnend ) 47 48/* 49 * Ok, we need to do extra processing, enter the slow path. 50 */ 51fast_work_pending: 52 str r0, [sp, #S_R0+S_OFF]! @ returned r0 53work_pending: 54 mov r0, sp @ 'regs' 55 mov r2, why @ 'syscall' 56 bl do_work_pending 57 cmp r0, #0 58 beq no_work_pending 59 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) 60 ldmia sp, {r0 - r6} @ have to reload r0 - r6 61 b local_restart @ ... and off we go 62 63/* 64 * "slow" syscall return path. "why" tells us if this was a real syscall. 65 */ 66ENTRY(ret_to_user) 67ret_slow_syscall: 68 disable_irq @ disable interrupts 69ENTRY(ret_to_user_from_irq) 70 ldr r1, [tsk, #TI_FLAGS] 71 tst r1, #_TIF_WORK_MASK 72 bne work_pending 73no_work_pending: 74#if defined(CONFIG_IRQSOFF_TRACER) 75 asm_trace_hardirqs_on 76#endif 77 /* perform architecture specific actions before user return */ 78 arch_ret_to_user r1, lr 79 80 restore_user_regs fast = 0, offset = 0 81ENDPROC(ret_to_user_from_irq) 82ENDPROC(ret_to_user) 83 84/* 85 * This is how we return from a fork. 86 */ 87ENTRY(ret_from_fork) 88 bl schedule_tail 89 cmp r5, #0 90 movne r0, r4 91 adrne lr, BSYM(1f) 92 movne pc, r5 931: get_thread_info tsk 94 b ret_slow_syscall 95ENDPROC(ret_from_fork) 96 97 .equ NR_syscalls,0 98#define CALL(x) .equ NR_syscalls,NR_syscalls+1 99#include "calls.S" 100 101/* 102 * Ensure that the system call table is equal to __NR_syscalls, 103 * which is the value the rest of the system sees 104 */ 105.ifne NR_syscalls - __NR_syscalls 106.error "__NR_syscalls is not equal to the size of the syscall table" 107.endif 108 109#undef CALL 110#define CALL(x) .long x 111 112#ifdef CONFIG_FUNCTION_TRACER 113/* 114 * When compiling with -pg, gcc inserts a call to the mcount routine at the 115 * start of every function. In mcount, apart from the function's address (in 116 * lr), we need to get hold of the function's caller's address. 117 * 118 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this: 119 * 120 * bl mcount 121 * 122 * These versions have the limitation that in order for the mcount routine to 123 * be able to determine the function's caller's address, an APCS-style frame 124 * pointer (which is set up with something like the code below) is required. 125 * 126 * mov ip, sp 127 * push {fp, ip, lr, pc} 128 * sub fp, ip, #4 129 * 130 * With EABI, these frame pointers are not available unless -mapcs-frame is 131 * specified, and if building as Thumb-2, not even then. 132 * 133 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount, 134 * with call sites like: 135 * 136 * push {lr} 137 * bl __gnu_mcount_nc 138 * 139 * With these compilers, frame pointers are not necessary. 140 * 141 * mcount can be thought of as a function called in the middle of a subroutine 142 * call. As such, it needs to be transparent for both the caller and the 143 * callee: the original lr needs to be restored when leaving mcount, and no 144 * registers should be clobbered. (In the __gnu_mcount_nc implementation, we 145 * clobber the ip register. This is OK because the ARM calling convention 146 * allows it to be clobbered in subroutines and doesn't use it to hold 147 * parameters.) 148 * 149 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0" 150 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see 151 * arch/arm/kernel/ftrace.c). 152 */ 153 154#ifndef CONFIG_OLD_MCOUNT 155#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4)) 156#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0. 157#endif 158#endif 159 160.macro mcount_adjust_addr rd, rn 161 bic \rd, \rn, #1 @ clear the Thumb bit if present 162 sub \rd, \rd, #MCOUNT_INSN_SIZE 163.endm 164 165.macro __mcount suffix 166 mcount_enter 167 ldr r0, =ftrace_trace_function 168 ldr r2, [r0] 169 adr r0, .Lftrace_stub 170 cmp r0, r2 171 bne 1f 172 173#ifdef CONFIG_FUNCTION_GRAPH_TRACER 174 ldr r1, =ftrace_graph_return 175 ldr r2, [r1] 176 cmp r0, r2 177 bne ftrace_graph_caller\suffix 178 179 ldr r1, =ftrace_graph_entry 180 ldr r2, [r1] 181 ldr r0, =ftrace_graph_entry_stub 182 cmp r0, r2 183 bne ftrace_graph_caller\suffix 184#endif 185 186 mcount_exit 187 1881: mcount_get_lr r1 @ lr of instrumented func 189 mcount_adjust_addr r0, lr @ instrumented function 190 adr lr, BSYM(2f) 191 mov pc, r2 1922: mcount_exit 193.endm 194 195.macro __ftrace_caller suffix 196 mcount_enter 197 198 mcount_get_lr r1 @ lr of instrumented func 199 mcount_adjust_addr r0, lr @ instrumented function 200 201 .globl ftrace_call\suffix 202ftrace_call\suffix: 203 bl ftrace_stub 204 205#ifdef CONFIG_FUNCTION_GRAPH_TRACER 206 .globl ftrace_graph_call\suffix 207ftrace_graph_call\suffix: 208 mov r0, r0 209#endif 210 211 mcount_exit 212.endm 213 214.macro __ftrace_graph_caller 215 sub r0, fp, #4 @ &lr of instrumented routine (&parent) 216#ifdef CONFIG_DYNAMIC_FTRACE 217 @ called from __ftrace_caller, saved in mcount_enter 218 ldr r1, [sp, #16] @ instrumented routine (func) 219 mcount_adjust_addr r1, r1 220#else 221 @ called from __mcount, untouched in lr 222 mcount_adjust_addr r1, lr @ instrumented routine (func) 223#endif 224 mov r2, fp @ frame pointer 225 bl prepare_ftrace_return 226 mcount_exit 227.endm 228 229#ifdef CONFIG_OLD_MCOUNT 230/* 231 * mcount 232 */ 233 234.macro mcount_enter 235 stmdb sp!, {r0-r3, lr} 236.endm 237 238.macro mcount_get_lr reg 239 ldr \reg, [fp, #-4] 240.endm 241 242.macro mcount_exit 243 ldr lr, [fp, #-4] 244 ldmia sp!, {r0-r3, pc} 245.endm 246 247ENTRY(mcount) 248#ifdef CONFIG_DYNAMIC_FTRACE 249 stmdb sp!, {lr} 250 ldr lr, [fp, #-4] 251 ldmia sp!, {pc} 252#else 253 __mcount _old 254#endif 255ENDPROC(mcount) 256 257#ifdef CONFIG_DYNAMIC_FTRACE 258ENTRY(ftrace_caller_old) 259 __ftrace_caller _old 260ENDPROC(ftrace_caller_old) 261#endif 262 263#ifdef CONFIG_FUNCTION_GRAPH_TRACER 264ENTRY(ftrace_graph_caller_old) 265 __ftrace_graph_caller 266ENDPROC(ftrace_graph_caller_old) 267#endif 268 269.purgem mcount_enter 270.purgem mcount_get_lr 271.purgem mcount_exit 272#endif 273 274/* 275 * __gnu_mcount_nc 276 */ 277 278.macro mcount_enter 279/* 280 * This pad compensates for the push {lr} at the call site. Note that we are 281 * unable to unwind through a function which does not otherwise save its lr. 282 */ 283 UNWIND(.pad #4) 284 stmdb sp!, {r0-r3, lr} 285 UNWIND(.save {r0-r3, lr}) 286.endm 287 288.macro mcount_get_lr reg 289 ldr \reg, [sp, #20] 290.endm 291 292.macro mcount_exit 293 ldmia sp!, {r0-r3, ip, lr} 294 mov pc, ip 295.endm 296 297ENTRY(__gnu_mcount_nc) 298UNWIND(.fnstart) 299#ifdef CONFIG_DYNAMIC_FTRACE 300 mov ip, lr 301 ldmia sp!, {lr} 302 mov pc, ip 303#else 304 __mcount 305#endif 306UNWIND(.fnend) 307ENDPROC(__gnu_mcount_nc) 308 309#ifdef CONFIG_DYNAMIC_FTRACE 310ENTRY(ftrace_caller) 311UNWIND(.fnstart) 312 __ftrace_caller 313UNWIND(.fnend) 314ENDPROC(ftrace_caller) 315#endif 316 317#ifdef CONFIG_FUNCTION_GRAPH_TRACER 318ENTRY(ftrace_graph_caller) 319UNWIND(.fnstart) 320 __ftrace_graph_caller 321UNWIND(.fnend) 322ENDPROC(ftrace_graph_caller) 323#endif 324 325.purgem mcount_enter 326.purgem mcount_get_lr 327.purgem mcount_exit 328 329#ifdef CONFIG_FUNCTION_GRAPH_TRACER 330 .globl return_to_handler 331return_to_handler: 332 stmdb sp!, {r0-r3} 333 mov r0, fp @ frame pointer 334 bl ftrace_return_to_handler 335 mov lr, r0 @ r0 has real ret addr 336 ldmia sp!, {r0-r3} 337 mov pc, lr 338#endif 339 340ENTRY(ftrace_stub) 341.Lftrace_stub: 342 mov pc, lr 343ENDPROC(ftrace_stub) 344 345#endif /* CONFIG_FUNCTION_TRACER */ 346 347/*============================================================================= 348 * SWI handler 349 *----------------------------------------------------------------------------- 350 */ 351 352 .align 5 353ENTRY(vector_swi) 354 sub sp, sp, #S_FRAME_SIZE 355 stmia sp, {r0 - r12} @ Calling r0 - r12 356 ARM( add r8, sp, #S_PC ) 357 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 358 THUMB( mov r8, sp ) 359 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 360 mrs r8, spsr @ called from non-FIQ mode, so ok. 361 str lr, [sp, #S_PC] @ Save calling PC 362 str r8, [sp, #S_PSR] @ Save CPSR 363 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 364 zero_fp 365 366 /* 367 * Get the system call number. 368 */ 369 370#if defined(CONFIG_OABI_COMPAT) 371 372 /* 373 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 374 * value to determine if it is an EABI or an old ABI call. 375 */ 376#ifdef CONFIG_ARM_THUMB 377 tst r8, #PSR_T_BIT 378 movne r10, #0 @ no thumb OABI emulation 379 ldreq r10, [lr, #-4] @ get SWI instruction 380#else 381 ldr r10, [lr, #-4] @ get SWI instruction 382#endif 383#ifdef CONFIG_CPU_ENDIAN_BE8 384 rev r10, r10 @ little endian instruction 385#endif 386 387#elif defined(CONFIG_AEABI) 388 389 /* 390 * Pure EABI user space always put syscall number into scno (r7). 391 */ 392#elif defined(CONFIG_ARM_THUMB) 393 /* Legacy ABI only, possibly thumb mode. */ 394 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs 395 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 396 ldreq scno, [lr, #-4] 397 398#else 399 /* Legacy ABI only. */ 400 ldr scno, [lr, #-4] @ get SWI instruction 401#endif 402 403#ifdef CONFIG_ALIGNMENT_TRAP 404 ldr ip, __cr_alignment 405 ldr ip, [ip] 406 mcr p15, 0, ip, c1, c0 @ update control register 407#endif 408 enable_irq 409 410 get_thread_info tsk 411 adr tbl, sys_call_table @ load syscall table pointer 412 413#if defined(CONFIG_OABI_COMPAT) 414 /* 415 * If the swi argument is zero, this is an EABI call and we do nothing. 416 * 417 * If this is an old ABI call, get the syscall number into scno and 418 * get the old ABI syscall table address. 419 */ 420 bics r10, r10, #0xff000000 421 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 422 ldrne tbl, =sys_oabi_call_table 423#elif !defined(CONFIG_AEABI) 424 bic scno, scno, #0xff000000 @ mask off SWI op-code 425 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 426#endif 427 428local_restart: 429 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 430 stmdb sp!, {r4, r5} @ push fifth and sixth args 431 432 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 433 bne __sys_trace 434 435 cmp scno, #NR_syscalls @ check upper syscall limit 436 adr lr, BSYM(ret_fast_syscall) @ return address 437 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 438 439 add r1, sp, #S_OFF 4402: mov why, #0 @ no longer a real syscall 441 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 442 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 443 bcs arm_syscall 444 b sys_ni_syscall @ not private func 445ENDPROC(vector_swi) 446 447 /* 448 * This is the really slow path. We're going to be doing 449 * context switches, and waiting for our parent to respond. 450 */ 451__sys_trace: 452 mov r1, scno 453 add r0, sp, #S_OFF 454 bl syscall_trace_enter 455 456 adr lr, BSYM(__sys_trace_return) @ return address 457 mov scno, r0 @ syscall number (possibly new) 458 add r1, sp, #S_R0 + S_OFF @ pointer to regs 459 cmp scno, #NR_syscalls @ check upper syscall limit 460 ldmccia r1, {r0 - r6} @ have to reload r0 - r6 461 stmccia sp, {r4, r5} @ and update the stack args 462 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 463 cmp scno, #-1 @ skip the syscall? 464 bne 2b 465 add sp, sp, #S_OFF @ restore stack 466 b ret_slow_syscall 467 468__sys_trace_return: 469 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 470 mov r0, sp 471 bl syscall_trace_exit 472 b ret_slow_syscall 473 474 .align 5 475#ifdef CONFIG_ALIGNMENT_TRAP 476 .type __cr_alignment, #object 477__cr_alignment: 478 .word cr_alignment 479#endif 480 .ltorg 481 482/* 483 * This is the syscall table declaration for native ABI syscalls. 484 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 485 */ 486#define ABI(native, compat) native 487#ifdef CONFIG_AEABI 488#define OBSOLETE(syscall) sys_ni_syscall 489#else 490#define OBSOLETE(syscall) syscall 491#endif 492 493 .type sys_call_table, #object 494ENTRY(sys_call_table) 495#include "calls.S" 496#undef ABI 497#undef OBSOLETE 498 499/*============================================================================ 500 * Special system call wrappers 501 */ 502@ r0 = syscall number 503@ r8 = syscall table 504sys_syscall: 505 bic scno, r0, #__NR_OABI_SYSCALL_BASE 506 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 507 cmpne scno, #NR_syscalls @ check range 508 stmloia sp, {r5, r6} @ shuffle args 509 movlo r0, r1 510 movlo r1, r2 511 movlo r2, r3 512 movlo r3, r4 513 ldrlo pc, [tbl, scno, lsl #2] 514 b sys_ni_syscall 515ENDPROC(sys_syscall) 516 517sys_sigreturn_wrapper: 518 add r0, sp, #S_OFF 519 mov why, #0 @ prevent syscall restart handling 520 b sys_sigreturn 521ENDPROC(sys_sigreturn_wrapper) 522 523sys_rt_sigreturn_wrapper: 524 add r0, sp, #S_OFF 525 mov why, #0 @ prevent syscall restart handling 526 b sys_rt_sigreturn 527ENDPROC(sys_rt_sigreturn_wrapper) 528 529sys_statfs64_wrapper: 530 teq r1, #88 531 moveq r1, #84 532 b sys_statfs64 533ENDPROC(sys_statfs64_wrapper) 534 535sys_fstatfs64_wrapper: 536 teq r1, #88 537 moveq r1, #84 538 b sys_fstatfs64 539ENDPROC(sys_fstatfs64_wrapper) 540 541/* 542 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 543 * offset, we return EINVAL. 544 */ 545sys_mmap2: 546#if PAGE_SHIFT > 12 547 tst r5, #PGOFF_MASK 548 moveq r5, r5, lsr #PAGE_SHIFT - 12 549 streq r5, [sp, #4] 550 beq sys_mmap_pgoff 551 mov r0, #-EINVAL 552 mov pc, lr 553#else 554 str r5, [sp, #4] 555 b sys_mmap_pgoff 556#endif 557ENDPROC(sys_mmap2) 558 559#ifdef CONFIG_OABI_COMPAT 560 561/* 562 * These are syscalls with argument register differences 563 */ 564 565sys_oabi_pread64: 566 stmia sp, {r3, r4} 567 b sys_pread64 568ENDPROC(sys_oabi_pread64) 569 570sys_oabi_pwrite64: 571 stmia sp, {r3, r4} 572 b sys_pwrite64 573ENDPROC(sys_oabi_pwrite64) 574 575sys_oabi_truncate64: 576 mov r3, r2 577 mov r2, r1 578 b sys_truncate64 579ENDPROC(sys_oabi_truncate64) 580 581sys_oabi_ftruncate64: 582 mov r3, r2 583 mov r2, r1 584 b sys_ftruncate64 585ENDPROC(sys_oabi_ftruncate64) 586 587sys_oabi_readahead: 588 str r3, [sp] 589 mov r3, r2 590 mov r2, r1 591 b sys_readahead 592ENDPROC(sys_oabi_readahead) 593 594/* 595 * Let's declare a second syscall table for old ABI binaries 596 * using the compatibility syscall entries. 597 */ 598#define ABI(native, compat) compat 599#define OBSOLETE(syscall) syscall 600 601 .type sys_oabi_call_table, #object 602ENTRY(sys_oabi_call_table) 603#include "calls.S" 604#undef ABI 605#undef OBSOLETE 606 607#endif 608 609