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 <mach/entry-macro.S> 14#include <asm/unwind.h> 15 16#include "entry-header.S" 17 18 19 .align 5 20/* 21 * This is the fast syscall return path. We do as little as 22 * possible here, and this includes saving r0 back into the SVC 23 * stack. 24 */ 25ret_fast_syscall: 26 UNWIND(.fnstart ) 27 UNWIND(.cantunwind ) 28 disable_irq @ disable interrupts 29 ldr r1, [tsk, #TI_FLAGS] 30 tst r1, #_TIF_WORK_MASK 31 bne fast_work_pending 32 33 /* perform architecture specific actions before user return */ 34 arch_ret_to_user r1, lr 35 36 restore_user_regs fast = 1, offset = S_OFF 37 UNWIND(.fnend ) 38 39/* 40 * Ok, we need to do extra processing, enter the slow path. 41 */ 42fast_work_pending: 43 str r0, [sp, #S_R0+S_OFF]! @ returned r0 44work_pending: 45 tst r1, #_TIF_NEED_RESCHED 46 bne work_resched 47 tst r1, #_TIF_SIGPENDING|_TIF_NOTIFY_RESUME 48 beq no_work_pending 49 mov r0, sp @ 'regs' 50 mov r2, why @ 'syscall' 51 tst r1, #_TIF_SIGPENDING @ delivering a signal? 52 movne why, #0 @ prevent further restarts 53 bl do_notify_resume 54 b ret_slow_syscall @ Check work again 55 56work_resched: 57 bl schedule 58/* 59 * "slow" syscall return path. "why" tells us if this was a real syscall. 60 */ 61ENTRY(ret_to_user) 62ret_slow_syscall: 63 disable_irq @ disable interrupts 64 ldr r1, [tsk, #TI_FLAGS] 65 tst r1, #_TIF_WORK_MASK 66 bne work_pending 67no_work_pending: 68 /* perform architecture specific actions before user return */ 69 arch_ret_to_user r1, lr 70 71 restore_user_regs fast = 0, offset = 0 72ENDPROC(ret_to_user) 73 74/* 75 * This is how we return from a fork. 76 */ 77ENTRY(ret_from_fork) 78 bl schedule_tail 79 get_thread_info tsk 80 ldr r1, [tsk, #TI_FLAGS] @ check for syscall tracing 81 mov why, #1 82 tst r1, #_TIF_SYSCALL_TRACE @ are we tracing syscalls? 83 beq ret_slow_syscall 84 mov r1, sp 85 mov r0, #1 @ trace exit [IP = 1] 86 bl syscall_trace 87 b ret_slow_syscall 88ENDPROC(ret_from_fork) 89 90 .equ NR_syscalls,0 91#define CALL(x) .equ NR_syscalls,NR_syscalls+1 92#include "calls.S" 93#undef CALL 94#define CALL(x) .long x 95 96#ifdef CONFIG_FUNCTION_TRACER 97/* 98 * When compiling with -pg, gcc inserts a call to the mcount routine at the 99 * start of every function. In mcount, apart from the function's address (in 100 * lr), we need to get hold of the function's caller's address. 101 * 102 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this: 103 * 104 * bl mcount 105 * 106 * These versions have the limitation that in order for the mcount routine to 107 * be able to determine the function's caller's address, an APCS-style frame 108 * pointer (which is set up with something like the code below) is required. 109 * 110 * mov ip, sp 111 * push {fp, ip, lr, pc} 112 * sub fp, ip, #4 113 * 114 * With EABI, these frame pointers are not available unless -mapcs-frame is 115 * specified, and if building as Thumb-2, not even then. 116 * 117 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount, 118 * with call sites like: 119 * 120 * push {lr} 121 * bl __gnu_mcount_nc 122 * 123 * With these compilers, frame pointers are not necessary. 124 * 125 * mcount can be thought of as a function called in the middle of a subroutine 126 * call. As such, it needs to be transparent for both the caller and the 127 * callee: the original lr needs to be restored when leaving mcount, and no 128 * registers should be clobbered. (In the __gnu_mcount_nc implementation, we 129 * clobber the ip register. This is OK because the ARM calling convention 130 * allows it to be clobbered in subroutines and doesn't use it to hold 131 * parameters.) 132 * 133 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0" 134 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see 135 * arch/arm/kernel/ftrace.c). 136 */ 137 138#ifndef CONFIG_OLD_MCOUNT 139#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4)) 140#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0. 141#endif 142#endif 143 144.macro __mcount suffix 145 mcount_enter 146 ldr r0, =ftrace_trace_function 147 ldr r2, [r0] 148 adr r0, .Lftrace_stub 149 cmp r0, r2 150 bne 1f 151 152#ifdef CONFIG_FUNCTION_GRAPH_TRACER 153 ldr r1, =ftrace_graph_return 154 ldr r2, [r1] 155 cmp r0, r2 156 bne ftrace_graph_caller\suffix 157 158 ldr r1, =ftrace_graph_entry 159 ldr r2, [r1] 160 ldr r0, =ftrace_graph_entry_stub 161 cmp r0, r2 162 bne ftrace_graph_caller\suffix 163#endif 164 165 mcount_exit 166 1671: mcount_get_lr r1 @ lr of instrumented func 168 mov r0, lr @ instrumented function 169 sub r0, r0, #MCOUNT_INSN_SIZE 170 adr lr, BSYM(2f) 171 mov pc, r2 1722: mcount_exit 173.endm 174 175.macro __ftrace_caller suffix 176 mcount_enter 177 178 mcount_get_lr r1 @ lr of instrumented func 179 mov r0, lr @ instrumented function 180 sub r0, r0, #MCOUNT_INSN_SIZE 181 182 .globl ftrace_call\suffix 183ftrace_call\suffix: 184 bl ftrace_stub 185 186 mcount_exit 187.endm 188 189.macro __ftrace_graph_caller 190 sub r0, fp, #4 @ &lr of instrumented routine (&parent) 191 mov r1, lr @ instrumented routine (func) 192 sub r1, r1, #MCOUNT_INSN_SIZE 193 mov r2, fp @ frame pointer 194 bl prepare_ftrace_return 195 mcount_exit 196.endm 197 198#ifdef CONFIG_OLD_MCOUNT 199/* 200 * mcount 201 */ 202 203.macro mcount_enter 204 stmdb sp!, {r0-r3, lr} 205.endm 206 207.macro mcount_get_lr reg 208 ldr \reg, [fp, #-4] 209.endm 210 211.macro mcount_exit 212 ldr lr, [fp, #-4] 213 ldmia sp!, {r0-r3, pc} 214.endm 215 216ENTRY(mcount) 217#ifdef CONFIG_DYNAMIC_FTRACE 218 stmdb sp!, {lr} 219 ldr lr, [fp, #-4] 220 ldmia sp!, {pc} 221#else 222 __mcount _old 223#endif 224ENDPROC(mcount) 225 226#ifdef CONFIG_DYNAMIC_FTRACE 227ENTRY(ftrace_caller_old) 228 __ftrace_caller _old 229ENDPROC(ftrace_caller_old) 230#endif 231 232#ifdef CONFIG_FUNCTION_GRAPH_TRACER 233ENTRY(ftrace_graph_caller_old) 234 __ftrace_graph_caller 235ENDPROC(ftrace_graph_caller_old) 236#endif 237 238.purgem mcount_enter 239.purgem mcount_get_lr 240.purgem mcount_exit 241#endif 242 243/* 244 * __gnu_mcount_nc 245 */ 246 247.macro mcount_enter 248 stmdb sp!, {r0-r3, lr} 249.endm 250 251.macro mcount_get_lr reg 252 ldr \reg, [sp, #20] 253.endm 254 255.macro mcount_exit 256 ldmia sp!, {r0-r3, ip, lr} 257 mov pc, ip 258.endm 259 260ENTRY(__gnu_mcount_nc) 261#ifdef CONFIG_DYNAMIC_FTRACE 262 mov ip, lr 263 ldmia sp!, {lr} 264 mov pc, ip 265#else 266 __mcount 267#endif 268ENDPROC(__gnu_mcount_nc) 269 270#ifdef CONFIG_DYNAMIC_FTRACE 271ENTRY(ftrace_caller) 272 __ftrace_caller 273ENDPROC(ftrace_caller) 274#endif 275 276#ifdef CONFIG_FUNCTION_GRAPH_TRACER 277ENTRY(ftrace_graph_caller) 278 __ftrace_graph_caller 279ENDPROC(ftrace_graph_caller) 280#endif 281 282.purgem mcount_enter 283.purgem mcount_get_lr 284.purgem mcount_exit 285 286#ifdef CONFIG_FUNCTION_GRAPH_TRACER 287 .globl return_to_handler 288return_to_handler: 289 stmdb sp!, {r0-r3} 290 mov r0, fp @ frame pointer 291 bl ftrace_return_to_handler 292 mov lr, r0 @ r0 has real ret addr 293 ldmia sp!, {r0-r3} 294 mov pc, lr 295#endif 296 297ENTRY(ftrace_stub) 298.Lftrace_stub: 299 mov pc, lr 300ENDPROC(ftrace_stub) 301 302#endif /* CONFIG_FUNCTION_TRACER */ 303 304/*============================================================================= 305 * SWI handler 306 *----------------------------------------------------------------------------- 307 */ 308 309 /* If we're optimising for StrongARM the resulting code won't 310 run on an ARM7 and we can save a couple of instructions. 311 --pb */ 312#ifdef CONFIG_CPU_ARM710 313#define A710(code...) code 314.Larm710bug: 315 ldmia sp, {r0 - lr}^ @ Get calling r0 - lr 316 mov r0, r0 317 add sp, sp, #S_FRAME_SIZE 318 subs pc, lr, #4 319#else 320#define A710(code...) 321#endif 322 323 .align 5 324ENTRY(vector_swi) 325 sub sp, sp, #S_FRAME_SIZE 326 stmia sp, {r0 - r12} @ Calling r0 - r12 327 ARM( add r8, sp, #S_PC ) 328 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 329 THUMB( mov r8, sp ) 330 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 331 mrs r8, spsr @ called from non-FIQ mode, so ok. 332 str lr, [sp, #S_PC] @ Save calling PC 333 str r8, [sp, #S_PSR] @ Save CPSR 334 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 335 zero_fp 336 337 /* 338 * Get the system call number. 339 */ 340 341#if defined(CONFIG_OABI_COMPAT) 342 343 /* 344 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 345 * value to determine if it is an EABI or an old ABI call. 346 */ 347#ifdef CONFIG_ARM_THUMB 348 tst r8, #PSR_T_BIT 349 movne r10, #0 @ no thumb OABI emulation 350 ldreq r10, [lr, #-4] @ get SWI instruction 351#else 352 ldr r10, [lr, #-4] @ get SWI instruction 353 A710( and ip, r10, #0x0f000000 @ check for SWI ) 354 A710( teq ip, #0x0f000000 ) 355 A710( bne .Larm710bug ) 356#endif 357#ifdef CONFIG_CPU_ENDIAN_BE8 358 rev r10, r10 @ little endian instruction 359#endif 360 361#elif defined(CONFIG_AEABI) 362 363 /* 364 * Pure EABI user space always put syscall number into scno (r7). 365 */ 366 A710( ldr ip, [lr, #-4] @ get SWI instruction ) 367 A710( and ip, ip, #0x0f000000 @ check for SWI ) 368 A710( teq ip, #0x0f000000 ) 369 A710( bne .Larm710bug ) 370 371#elif defined(CONFIG_ARM_THUMB) 372 373 /* Legacy ABI only, possibly thumb mode. */ 374 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs 375 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 376 ldreq scno, [lr, #-4] 377 378#else 379 380 /* Legacy ABI only. */ 381 ldr scno, [lr, #-4] @ get SWI instruction 382 A710( and ip, scno, #0x0f000000 @ check for SWI ) 383 A710( teq ip, #0x0f000000 ) 384 A710( bne .Larm710bug ) 385 386#endif 387 388#ifdef CONFIG_ALIGNMENT_TRAP 389 ldr ip, __cr_alignment 390 ldr ip, [ip] 391 mcr p15, 0, ip, c1, c0 @ update control register 392#endif 393 enable_irq 394 395 get_thread_info tsk 396 adr tbl, sys_call_table @ load syscall table pointer 397 398#if defined(CONFIG_OABI_COMPAT) 399 /* 400 * If the swi argument is zero, this is an EABI call and we do nothing. 401 * 402 * If this is an old ABI call, get the syscall number into scno and 403 * get the old ABI syscall table address. 404 */ 405 bics r10, r10, #0xff000000 406 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 407 ldrne tbl, =sys_oabi_call_table 408#elif !defined(CONFIG_AEABI) 409 bic scno, scno, #0xff000000 @ mask off SWI op-code 410 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 411#endif 412 413 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 414 stmdb sp!, {r4, r5} @ push fifth and sixth args 415 416#ifdef CONFIG_SECCOMP 417 tst r10, #_TIF_SECCOMP 418 beq 1f 419 mov r0, scno 420 bl __secure_computing 421 add r0, sp, #S_R0 + S_OFF @ pointer to regs 422 ldmia r0, {r0 - r3} @ have to reload r0 - r3 4231: 424#endif 425 426 tst r10, #_TIF_SYSCALL_TRACE @ are we tracing syscalls? 427 bne __sys_trace 428 429 cmp scno, #NR_syscalls @ check upper syscall limit 430 adr lr, BSYM(ret_fast_syscall) @ return address 431 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 432 433 add r1, sp, #S_OFF 4342: mov why, #0 @ no longer a real syscall 435 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 436 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 437 bcs arm_syscall 438 b sys_ni_syscall @ not private func 439ENDPROC(vector_swi) 440 441 /* 442 * This is the really slow path. We're going to be doing 443 * context switches, and waiting for our parent to respond. 444 */ 445__sys_trace: 446 mov r2, scno 447 add r1, sp, #S_OFF 448 mov r0, #0 @ trace entry [IP = 0] 449 bl syscall_trace 450 451 adr lr, BSYM(__sys_trace_return) @ return address 452 mov scno, r0 @ syscall number (possibly new) 453 add r1, sp, #S_R0 + S_OFF @ pointer to regs 454 cmp scno, #NR_syscalls @ check upper syscall limit 455 ldmccia r1, {r0 - r3} @ have to reload r0 - r3 456 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 457 b 2b 458 459__sys_trace_return: 460 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 461 mov r2, scno 462 mov r1, sp 463 mov r0, #1 @ trace exit [IP = 1] 464 bl syscall_trace 465 b ret_slow_syscall 466 467 .align 5 468#ifdef CONFIG_ALIGNMENT_TRAP 469 .type __cr_alignment, #object 470__cr_alignment: 471 .word cr_alignment 472#endif 473 .ltorg 474 475/* 476 * This is the syscall table declaration for native ABI syscalls. 477 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 478 */ 479#define ABI(native, compat) native 480#ifdef CONFIG_AEABI 481#define OBSOLETE(syscall) sys_ni_syscall 482#else 483#define OBSOLETE(syscall) syscall 484#endif 485 486 .type sys_call_table, #object 487ENTRY(sys_call_table) 488#include "calls.S" 489#undef ABI 490#undef OBSOLETE 491 492/*============================================================================ 493 * Special system call wrappers 494 */ 495@ r0 = syscall number 496@ r8 = syscall table 497sys_syscall: 498 bic scno, r0, #__NR_OABI_SYSCALL_BASE 499 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 500 cmpne scno, #NR_syscalls @ check range 501 stmloia sp, {r5, r6} @ shuffle args 502 movlo r0, r1 503 movlo r1, r2 504 movlo r2, r3 505 movlo r3, r4 506 ldrlo pc, [tbl, scno, lsl #2] 507 b sys_ni_syscall 508ENDPROC(sys_syscall) 509 510sys_fork_wrapper: 511 add r0, sp, #S_OFF 512 b sys_fork 513ENDPROC(sys_fork_wrapper) 514 515sys_vfork_wrapper: 516 add r0, sp, #S_OFF 517 b sys_vfork 518ENDPROC(sys_vfork_wrapper) 519 520sys_execve_wrapper: 521 add r3, sp, #S_OFF 522 b sys_execve 523ENDPROC(sys_execve_wrapper) 524 525sys_clone_wrapper: 526 add ip, sp, #S_OFF 527 str ip, [sp, #4] 528 b sys_clone 529ENDPROC(sys_clone_wrapper) 530 531sys_sigreturn_wrapper: 532 add r0, sp, #S_OFF 533 mov why, #0 @ prevent syscall restart handling 534 b sys_sigreturn 535ENDPROC(sys_sigreturn_wrapper) 536 537sys_rt_sigreturn_wrapper: 538 add r0, sp, #S_OFF 539 mov why, #0 @ prevent syscall restart handling 540 b sys_rt_sigreturn 541ENDPROC(sys_rt_sigreturn_wrapper) 542 543sys_sigaltstack_wrapper: 544 ldr r2, [sp, #S_OFF + S_SP] 545 b do_sigaltstack 546ENDPROC(sys_sigaltstack_wrapper) 547 548sys_statfs64_wrapper: 549 teq r1, #88 550 moveq r1, #84 551 b sys_statfs64 552ENDPROC(sys_statfs64_wrapper) 553 554sys_fstatfs64_wrapper: 555 teq r1, #88 556 moveq r1, #84 557 b sys_fstatfs64 558ENDPROC(sys_fstatfs64_wrapper) 559 560/* 561 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 562 * offset, we return EINVAL. 563 */ 564sys_mmap2: 565#if PAGE_SHIFT > 12 566 tst r5, #PGOFF_MASK 567 moveq r5, r5, lsr #PAGE_SHIFT - 12 568 streq r5, [sp, #4] 569 beq sys_mmap_pgoff 570 mov r0, #-EINVAL 571 mov pc, lr 572#else 573 str r5, [sp, #4] 574 b sys_mmap_pgoff 575#endif 576ENDPROC(sys_mmap2) 577 578#ifdef CONFIG_OABI_COMPAT 579 580/* 581 * These are syscalls with argument register differences 582 */ 583 584sys_oabi_pread64: 585 stmia sp, {r3, r4} 586 b sys_pread64 587ENDPROC(sys_oabi_pread64) 588 589sys_oabi_pwrite64: 590 stmia sp, {r3, r4} 591 b sys_pwrite64 592ENDPROC(sys_oabi_pwrite64) 593 594sys_oabi_truncate64: 595 mov r3, r2 596 mov r2, r1 597 b sys_truncate64 598ENDPROC(sys_oabi_truncate64) 599 600sys_oabi_ftruncate64: 601 mov r3, r2 602 mov r2, r1 603 b sys_ftruncate64 604ENDPROC(sys_oabi_ftruncate64) 605 606sys_oabi_readahead: 607 str r3, [sp] 608 mov r3, r2 609 mov r2, r1 610 b sys_readahead 611ENDPROC(sys_oabi_readahead) 612 613/* 614 * Let's declare a second syscall table for old ABI binaries 615 * using the compatibility syscall entries. 616 */ 617#define ABI(native, compat) compat 618#define OBSOLETE(syscall) syscall 619 620 .type sys_oabi_call_table, #object 621ENTRY(sys_oabi_call_table) 622#include "calls.S" 623#undef ABI 624#undef OBSOLETE 625 626#endif 627 628