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 tst r1, #_TIF_NEED_RESCHED 55 bne work_resched 56 /* 57 * TIF_SIGPENDING or TIF_NOTIFY_RESUME must've been set if we got here 58 */ 59 ldr r2, [sp, #S_PSR] 60 mov r0, sp @ 'regs' 61 tst r2, #15 @ are we returning to user mode? 62 bne no_work_pending @ no? just leave, then... 63 mov r2, why @ 'syscall' 64 tst r1, #_TIF_SIGPENDING @ delivering a signal? 65 movne why, #0 @ prevent further restarts 66 bl do_notify_resume 67 b ret_slow_syscall @ Check work again 68 69work_resched: 70 bl schedule 71/* 72 * "slow" syscall return path. "why" tells us if this was a real syscall. 73 */ 74ENTRY(ret_to_user) 75ret_slow_syscall: 76 disable_irq @ disable interrupts 77ENTRY(ret_to_user_from_irq) 78 ldr r1, [tsk, #TI_FLAGS] 79 tst r1, #_TIF_WORK_MASK 80 bne work_pending 81no_work_pending: 82#if defined(CONFIG_IRQSOFF_TRACER) 83 asm_trace_hardirqs_on 84#endif 85 /* perform architecture specific actions before user return */ 86 arch_ret_to_user r1, lr 87 88 restore_user_regs fast = 0, offset = 0 89ENDPROC(ret_to_user_from_irq) 90ENDPROC(ret_to_user) 91 92/* 93 * This is how we return from a fork. 94 */ 95ENTRY(ret_from_fork) 96 bl schedule_tail 97 get_thread_info tsk 98 mov why, #1 99 b ret_slow_syscall 100ENDPROC(ret_from_fork) 101 102 .equ NR_syscalls,0 103#define CALL(x) .equ NR_syscalls,NR_syscalls+1 104#include "calls.S" 105#undef CALL 106#define CALL(x) .long x 107 108#ifdef CONFIG_FUNCTION_TRACER 109/* 110 * When compiling with -pg, gcc inserts a call to the mcount routine at the 111 * start of every function. In mcount, apart from the function's address (in 112 * lr), we need to get hold of the function's caller's address. 113 * 114 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this: 115 * 116 * bl mcount 117 * 118 * These versions have the limitation that in order for the mcount routine to 119 * be able to determine the function's caller's address, an APCS-style frame 120 * pointer (which is set up with something like the code below) is required. 121 * 122 * mov ip, sp 123 * push {fp, ip, lr, pc} 124 * sub fp, ip, #4 125 * 126 * With EABI, these frame pointers are not available unless -mapcs-frame is 127 * specified, and if building as Thumb-2, not even then. 128 * 129 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount, 130 * with call sites like: 131 * 132 * push {lr} 133 * bl __gnu_mcount_nc 134 * 135 * With these compilers, frame pointers are not necessary. 136 * 137 * mcount can be thought of as a function called in the middle of a subroutine 138 * call. As such, it needs to be transparent for both the caller and the 139 * callee: the original lr needs to be restored when leaving mcount, and no 140 * registers should be clobbered. (In the __gnu_mcount_nc implementation, we 141 * clobber the ip register. This is OK because the ARM calling convention 142 * allows it to be clobbered in subroutines and doesn't use it to hold 143 * parameters.) 144 * 145 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0" 146 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see 147 * arch/arm/kernel/ftrace.c). 148 */ 149 150#ifndef CONFIG_OLD_MCOUNT 151#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4)) 152#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0. 153#endif 154#endif 155 156.macro mcount_adjust_addr rd, rn 157 bic \rd, \rn, #1 @ clear the Thumb bit if present 158 sub \rd, \rd, #MCOUNT_INSN_SIZE 159.endm 160 161.macro __mcount suffix 162 mcount_enter 163 ldr r0, =ftrace_trace_function 164 ldr r2, [r0] 165 adr r0, .Lftrace_stub 166 cmp r0, r2 167 bne 1f 168 169#ifdef CONFIG_FUNCTION_GRAPH_TRACER 170 ldr r1, =ftrace_graph_return 171 ldr r2, [r1] 172 cmp r0, r2 173 bne ftrace_graph_caller\suffix 174 175 ldr r1, =ftrace_graph_entry 176 ldr r2, [r1] 177 ldr r0, =ftrace_graph_entry_stub 178 cmp r0, r2 179 bne ftrace_graph_caller\suffix 180#endif 181 182 mcount_exit 183 1841: mcount_get_lr r1 @ lr of instrumented func 185 mcount_adjust_addr r0, lr @ instrumented function 186 adr lr, BSYM(2f) 187 mov pc, r2 1882: mcount_exit 189.endm 190 191.macro __ftrace_caller suffix 192 mcount_enter 193 194 mcount_get_lr r1 @ lr of instrumented func 195 mcount_adjust_addr r0, lr @ instrumented function 196 197 .globl ftrace_call\suffix 198ftrace_call\suffix: 199 bl ftrace_stub 200 201#ifdef CONFIG_FUNCTION_GRAPH_TRACER 202 .globl ftrace_graph_call\suffix 203ftrace_graph_call\suffix: 204 mov r0, r0 205#endif 206 207 mcount_exit 208.endm 209 210.macro __ftrace_graph_caller 211 sub r0, fp, #4 @ &lr of instrumented routine (&parent) 212#ifdef CONFIG_DYNAMIC_FTRACE 213 @ called from __ftrace_caller, saved in mcount_enter 214 ldr r1, [sp, #16] @ instrumented routine (func) 215 mcount_adjust_addr r1, r1 216#else 217 @ called from __mcount, untouched in lr 218 mcount_adjust_addr r1, lr @ instrumented routine (func) 219#endif 220 mov r2, fp @ frame pointer 221 bl prepare_ftrace_return 222 mcount_exit 223.endm 224 225#ifdef CONFIG_OLD_MCOUNT 226/* 227 * mcount 228 */ 229 230.macro mcount_enter 231 stmdb sp!, {r0-r3, lr} 232.endm 233 234.macro mcount_get_lr reg 235 ldr \reg, [fp, #-4] 236.endm 237 238.macro mcount_exit 239 ldr lr, [fp, #-4] 240 ldmia sp!, {r0-r3, pc} 241.endm 242 243ENTRY(mcount) 244#ifdef CONFIG_DYNAMIC_FTRACE 245 stmdb sp!, {lr} 246 ldr lr, [fp, #-4] 247 ldmia sp!, {pc} 248#else 249 __mcount _old 250#endif 251ENDPROC(mcount) 252 253#ifdef CONFIG_DYNAMIC_FTRACE 254ENTRY(ftrace_caller_old) 255 __ftrace_caller _old 256ENDPROC(ftrace_caller_old) 257#endif 258 259#ifdef CONFIG_FUNCTION_GRAPH_TRACER 260ENTRY(ftrace_graph_caller_old) 261 __ftrace_graph_caller 262ENDPROC(ftrace_graph_caller_old) 263#endif 264 265.purgem mcount_enter 266.purgem mcount_get_lr 267.purgem mcount_exit 268#endif 269 270/* 271 * __gnu_mcount_nc 272 */ 273 274.macro mcount_enter 275 stmdb sp!, {r0-r3, lr} 276.endm 277 278.macro mcount_get_lr reg 279 ldr \reg, [sp, #20] 280.endm 281 282.macro mcount_exit 283 ldmia sp!, {r0-r3, ip, lr} 284 mov pc, ip 285.endm 286 287ENTRY(__gnu_mcount_nc) 288#ifdef CONFIG_DYNAMIC_FTRACE 289 mov ip, lr 290 ldmia sp!, {lr} 291 mov pc, ip 292#else 293 __mcount 294#endif 295ENDPROC(__gnu_mcount_nc) 296 297#ifdef CONFIG_DYNAMIC_FTRACE 298ENTRY(ftrace_caller) 299 __ftrace_caller 300ENDPROC(ftrace_caller) 301#endif 302 303#ifdef CONFIG_FUNCTION_GRAPH_TRACER 304ENTRY(ftrace_graph_caller) 305 __ftrace_graph_caller 306ENDPROC(ftrace_graph_caller) 307#endif 308 309.purgem mcount_enter 310.purgem mcount_get_lr 311.purgem mcount_exit 312 313#ifdef CONFIG_FUNCTION_GRAPH_TRACER 314 .globl return_to_handler 315return_to_handler: 316 stmdb sp!, {r0-r3} 317 mov r0, fp @ frame pointer 318 bl ftrace_return_to_handler 319 mov lr, r0 @ r0 has real ret addr 320 ldmia sp!, {r0-r3} 321 mov pc, lr 322#endif 323 324ENTRY(ftrace_stub) 325.Lftrace_stub: 326 mov pc, lr 327ENDPROC(ftrace_stub) 328 329#endif /* CONFIG_FUNCTION_TRACER */ 330 331/*============================================================================= 332 * SWI handler 333 *----------------------------------------------------------------------------- 334 */ 335 336 .align 5 337ENTRY(vector_swi) 338 sub sp, sp, #S_FRAME_SIZE 339 stmia sp, {r0 - r12} @ Calling r0 - r12 340 ARM( add r8, sp, #S_PC ) 341 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 342 THUMB( mov r8, sp ) 343 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 344 mrs r8, spsr @ called from non-FIQ mode, so ok. 345 str lr, [sp, #S_PC] @ Save calling PC 346 str r8, [sp, #S_PSR] @ Save CPSR 347 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 348 zero_fp 349 350 /* 351 * Get the system call number. 352 */ 353 354#if defined(CONFIG_OABI_COMPAT) 355 356 /* 357 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 358 * value to determine if it is an EABI or an old ABI call. 359 */ 360#ifdef CONFIG_ARM_THUMB 361 tst r8, #PSR_T_BIT 362 movne r10, #0 @ no thumb OABI emulation 363 ldreq r10, [lr, #-4] @ get SWI instruction 364#else 365 ldr r10, [lr, #-4] @ get SWI instruction 366#endif 367#ifdef CONFIG_CPU_ENDIAN_BE8 368 rev r10, r10 @ little endian instruction 369#endif 370 371#elif defined(CONFIG_AEABI) 372 373 /* 374 * Pure EABI user space always put syscall number into scno (r7). 375 */ 376#elif defined(CONFIG_ARM_THUMB) 377 /* Legacy ABI only, possibly thumb mode. */ 378 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs 379 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 380 ldreq scno, [lr, #-4] 381 382#else 383 /* Legacy ABI only. */ 384 ldr scno, [lr, #-4] @ get SWI instruction 385#endif 386 387#ifdef CONFIG_ALIGNMENT_TRAP 388 ldr ip, __cr_alignment 389 ldr ip, [ip] 390 mcr p15, 0, ip, c1, c0 @ update control register 391#endif 392 enable_irq 393 394 get_thread_info tsk 395 adr tbl, sys_call_table @ load syscall table pointer 396 397#if defined(CONFIG_OABI_COMPAT) 398 /* 399 * If the swi argument is zero, this is an EABI call and we do nothing. 400 * 401 * If this is an old ABI call, get the syscall number into scno and 402 * get the old ABI syscall table address. 403 */ 404 bics r10, r10, #0xff000000 405 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 406 ldrne tbl, =sys_oabi_call_table 407#elif !defined(CONFIG_AEABI) 408 bic scno, scno, #0xff000000 @ mask off SWI op-code 409 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 410#endif 411 412 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 413 stmdb sp!, {r4, r5} @ push fifth and sixth args 414 415#ifdef CONFIG_SECCOMP 416 tst r10, #_TIF_SECCOMP 417 beq 1f 418 mov r0, scno 419 bl __secure_computing 420 add r0, sp, #S_R0 + S_OFF @ pointer to regs 421 ldmia r0, {r0 - r3} @ have to reload r0 - r3 4221: 423#endif 424 425 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 426 bne __sys_trace 427 428 cmp scno, #NR_syscalls @ check upper syscall limit 429 adr lr, BSYM(ret_fast_syscall) @ return address 430 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 431 432 add r1, sp, #S_OFF 4332: mov why, #0 @ no longer a real syscall 434 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 435 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 436 bcs arm_syscall 437 b sys_ni_syscall @ not private func 438ENDPROC(vector_swi) 439 440 /* 441 * This is the really slow path. We're going to be doing 442 * context switches, and waiting for our parent to respond. 443 */ 444__sys_trace: 445 mov r1, scno 446 add r0, sp, #S_OFF 447 bl syscall_trace_enter 448 449 adr lr, BSYM(__sys_trace_return) @ return address 450 mov scno, r0 @ syscall number (possibly new) 451 add r1, sp, #S_R0 + S_OFF @ pointer to regs 452 cmp scno, #NR_syscalls @ check upper syscall limit 453 ldmccia r1, {r0 - r3} @ have to reload r0 - r3 454 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 455 b 2b 456 457__sys_trace_return: 458 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 459 mov r1, scno 460 mov r0, sp 461 bl syscall_trace_exit 462 b ret_slow_syscall 463 464 .align 5 465#ifdef CONFIG_ALIGNMENT_TRAP 466 .type __cr_alignment, #object 467__cr_alignment: 468 .word cr_alignment 469#endif 470 .ltorg 471 472/* 473 * This is the syscall table declaration for native ABI syscalls. 474 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 475 */ 476#define ABI(native, compat) native 477#ifdef CONFIG_AEABI 478#define OBSOLETE(syscall) sys_ni_syscall 479#else 480#define OBSOLETE(syscall) syscall 481#endif 482 483 .type sys_call_table, #object 484ENTRY(sys_call_table) 485#include "calls.S" 486#undef ABI 487#undef OBSOLETE 488 489/*============================================================================ 490 * Special system call wrappers 491 */ 492@ r0 = syscall number 493@ r8 = syscall table 494sys_syscall: 495 bic scno, r0, #__NR_OABI_SYSCALL_BASE 496 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 497 cmpne scno, #NR_syscalls @ check range 498 stmloia sp, {r5, r6} @ shuffle args 499 movlo r0, r1 500 movlo r1, r2 501 movlo r2, r3 502 movlo r3, r4 503 ldrlo pc, [tbl, scno, lsl #2] 504 b sys_ni_syscall 505ENDPROC(sys_syscall) 506 507sys_fork_wrapper: 508 add r0, sp, #S_OFF 509 b sys_fork 510ENDPROC(sys_fork_wrapper) 511 512sys_vfork_wrapper: 513 add r0, sp, #S_OFF 514 b sys_vfork 515ENDPROC(sys_vfork_wrapper) 516 517sys_execve_wrapper: 518 add r3, sp, #S_OFF 519 b sys_execve 520ENDPROC(sys_execve_wrapper) 521 522sys_clone_wrapper: 523 add ip, sp, #S_OFF 524 str ip, [sp, #4] 525 b sys_clone 526ENDPROC(sys_clone_wrapper) 527 528sys_sigreturn_wrapper: 529 add r0, sp, #S_OFF 530 mov why, #0 @ prevent syscall restart handling 531 b sys_sigreturn 532ENDPROC(sys_sigreturn_wrapper) 533 534sys_rt_sigreturn_wrapper: 535 add r0, sp, #S_OFF 536 mov why, #0 @ prevent syscall restart handling 537 b sys_rt_sigreturn 538ENDPROC(sys_rt_sigreturn_wrapper) 539 540sys_sigaltstack_wrapper: 541 ldr r2, [sp, #S_OFF + S_SP] 542 b do_sigaltstack 543ENDPROC(sys_sigaltstack_wrapper) 544 545sys_statfs64_wrapper: 546 teq r1, #88 547 moveq r1, #84 548 b sys_statfs64 549ENDPROC(sys_statfs64_wrapper) 550 551sys_fstatfs64_wrapper: 552 teq r1, #88 553 moveq r1, #84 554 b sys_fstatfs64 555ENDPROC(sys_fstatfs64_wrapper) 556 557/* 558 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 559 * offset, we return EINVAL. 560 */ 561sys_mmap2: 562#if PAGE_SHIFT > 12 563 tst r5, #PGOFF_MASK 564 moveq r5, r5, lsr #PAGE_SHIFT - 12 565 streq r5, [sp, #4] 566 beq sys_mmap_pgoff 567 mov r0, #-EINVAL 568 mov pc, lr 569#else 570 str r5, [sp, #4] 571 b sys_mmap_pgoff 572#endif 573ENDPROC(sys_mmap2) 574 575#ifdef CONFIG_OABI_COMPAT 576 577/* 578 * These are syscalls with argument register differences 579 */ 580 581sys_oabi_pread64: 582 stmia sp, {r3, r4} 583 b sys_pread64 584ENDPROC(sys_oabi_pread64) 585 586sys_oabi_pwrite64: 587 stmia sp, {r3, r4} 588 b sys_pwrite64 589ENDPROC(sys_oabi_pwrite64) 590 591sys_oabi_truncate64: 592 mov r3, r2 593 mov r2, r1 594 b sys_truncate64 595ENDPROC(sys_oabi_truncate64) 596 597sys_oabi_ftruncate64: 598 mov r3, r2 599 mov r2, r1 600 b sys_ftruncate64 601ENDPROC(sys_oabi_ftruncate64) 602 603sys_oabi_readahead: 604 str r3, [sp] 605 mov r3, r2 606 mov r2, r1 607 b sys_readahead 608ENDPROC(sys_oabi_readahead) 609 610/* 611 * Let's declare a second syscall table for old ABI binaries 612 * using the compatibility syscall entries. 613 */ 614#define ABI(native, compat) compat 615#define OBSOLETE(syscall) syscall 616 617 .type sys_oabi_call_table, #object 618ENTRY(sys_oabi_call_table) 619#include "calls.S" 620#undef ABI 621#undef OBSOLETE 622 623#endif 624 625