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 get_thread_info tsk 90 mov why, #1 91 b ret_slow_syscall 92ENDPROC(ret_from_fork) 93 94 .equ NR_syscalls,0 95#define CALL(x) .equ NR_syscalls,NR_syscalls+1 96#include "calls.S" 97 98/* 99 * Ensure that the system call table is equal to __NR_syscalls, 100 * which is the value the rest of the system sees 101 */ 102.ifne NR_syscalls - __NR_syscalls 103.error "__NR_syscalls is not equal to the size of the syscall table" 104.endif 105 106#undef CALL 107#define CALL(x) .long x 108 109#ifdef CONFIG_FUNCTION_TRACER 110/* 111 * When compiling with -pg, gcc inserts a call to the mcount routine at the 112 * start of every function. In mcount, apart from the function's address (in 113 * lr), we need to get hold of the function's caller's address. 114 * 115 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this: 116 * 117 * bl mcount 118 * 119 * These versions have the limitation that in order for the mcount routine to 120 * be able to determine the function's caller's address, an APCS-style frame 121 * pointer (which is set up with something like the code below) is required. 122 * 123 * mov ip, sp 124 * push {fp, ip, lr, pc} 125 * sub fp, ip, #4 126 * 127 * With EABI, these frame pointers are not available unless -mapcs-frame is 128 * specified, and if building as Thumb-2, not even then. 129 * 130 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount, 131 * with call sites like: 132 * 133 * push {lr} 134 * bl __gnu_mcount_nc 135 * 136 * With these compilers, frame pointers are not necessary. 137 * 138 * mcount can be thought of as a function called in the middle of a subroutine 139 * call. As such, it needs to be transparent for both the caller and the 140 * callee: the original lr needs to be restored when leaving mcount, and no 141 * registers should be clobbered. (In the __gnu_mcount_nc implementation, we 142 * clobber the ip register. This is OK because the ARM calling convention 143 * allows it to be clobbered in subroutines and doesn't use it to hold 144 * parameters.) 145 * 146 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0" 147 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see 148 * arch/arm/kernel/ftrace.c). 149 */ 150 151#ifndef CONFIG_OLD_MCOUNT 152#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4)) 153#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0. 154#endif 155#endif 156 157.macro mcount_adjust_addr rd, rn 158 bic \rd, \rn, #1 @ clear the Thumb bit if present 159 sub \rd, \rd, #MCOUNT_INSN_SIZE 160.endm 161 162.macro __mcount suffix 163 mcount_enter 164 ldr r0, =ftrace_trace_function 165 ldr r2, [r0] 166 adr r0, .Lftrace_stub 167 cmp r0, r2 168 bne 1f 169 170#ifdef CONFIG_FUNCTION_GRAPH_TRACER 171 ldr r1, =ftrace_graph_return 172 ldr r2, [r1] 173 cmp r0, r2 174 bne ftrace_graph_caller\suffix 175 176 ldr r1, =ftrace_graph_entry 177 ldr r2, [r1] 178 ldr r0, =ftrace_graph_entry_stub 179 cmp r0, r2 180 bne ftrace_graph_caller\suffix 181#endif 182 183 mcount_exit 184 1851: mcount_get_lr r1 @ lr of instrumented func 186 mcount_adjust_addr r0, lr @ instrumented function 187 adr lr, BSYM(2f) 188 mov pc, r2 1892: mcount_exit 190.endm 191 192.macro __ftrace_caller suffix 193 mcount_enter 194 195 mcount_get_lr r1 @ lr of instrumented func 196 mcount_adjust_addr r0, lr @ instrumented function 197 198 .globl ftrace_call\suffix 199ftrace_call\suffix: 200 bl ftrace_stub 201 202#ifdef CONFIG_FUNCTION_GRAPH_TRACER 203 .globl ftrace_graph_call\suffix 204ftrace_graph_call\suffix: 205 mov r0, r0 206#endif 207 208 mcount_exit 209.endm 210 211.macro __ftrace_graph_caller 212 sub r0, fp, #4 @ &lr of instrumented routine (&parent) 213#ifdef CONFIG_DYNAMIC_FTRACE 214 @ called from __ftrace_caller, saved in mcount_enter 215 ldr r1, [sp, #16] @ instrumented routine (func) 216 mcount_adjust_addr r1, r1 217#else 218 @ called from __mcount, untouched in lr 219 mcount_adjust_addr r1, lr @ instrumented routine (func) 220#endif 221 mov r2, fp @ frame pointer 222 bl prepare_ftrace_return 223 mcount_exit 224.endm 225 226#ifdef CONFIG_OLD_MCOUNT 227/* 228 * mcount 229 */ 230 231.macro mcount_enter 232 stmdb sp!, {r0-r3, lr} 233.endm 234 235.macro mcount_get_lr reg 236 ldr \reg, [fp, #-4] 237.endm 238 239.macro mcount_exit 240 ldr lr, [fp, #-4] 241 ldmia sp!, {r0-r3, pc} 242.endm 243 244ENTRY(mcount) 245#ifdef CONFIG_DYNAMIC_FTRACE 246 stmdb sp!, {lr} 247 ldr lr, [fp, #-4] 248 ldmia sp!, {pc} 249#else 250 __mcount _old 251#endif 252ENDPROC(mcount) 253 254#ifdef CONFIG_DYNAMIC_FTRACE 255ENTRY(ftrace_caller_old) 256 __ftrace_caller _old 257ENDPROC(ftrace_caller_old) 258#endif 259 260#ifdef CONFIG_FUNCTION_GRAPH_TRACER 261ENTRY(ftrace_graph_caller_old) 262 __ftrace_graph_caller 263ENDPROC(ftrace_graph_caller_old) 264#endif 265 266.purgem mcount_enter 267.purgem mcount_get_lr 268.purgem mcount_exit 269#endif 270 271/* 272 * __gnu_mcount_nc 273 */ 274 275.macro mcount_enter 276 stmdb sp!, {r0-r3, lr} 277.endm 278 279.macro mcount_get_lr reg 280 ldr \reg, [sp, #20] 281.endm 282 283.macro mcount_exit 284 ldmia sp!, {r0-r3, ip, lr} 285 mov pc, ip 286.endm 287 288ENTRY(__gnu_mcount_nc) 289#ifdef CONFIG_DYNAMIC_FTRACE 290 mov ip, lr 291 ldmia sp!, {lr} 292 mov pc, ip 293#else 294 __mcount 295#endif 296ENDPROC(__gnu_mcount_nc) 297 298#ifdef CONFIG_DYNAMIC_FTRACE 299ENTRY(ftrace_caller) 300 __ftrace_caller 301ENDPROC(ftrace_caller) 302#endif 303 304#ifdef CONFIG_FUNCTION_GRAPH_TRACER 305ENTRY(ftrace_graph_caller) 306 __ftrace_graph_caller 307ENDPROC(ftrace_graph_caller) 308#endif 309 310.purgem mcount_enter 311.purgem mcount_get_lr 312.purgem mcount_exit 313 314#ifdef CONFIG_FUNCTION_GRAPH_TRACER 315 .globl return_to_handler 316return_to_handler: 317 stmdb sp!, {r0-r3} 318 mov r0, fp @ frame pointer 319 bl ftrace_return_to_handler 320 mov lr, r0 @ r0 has real ret addr 321 ldmia sp!, {r0-r3} 322 mov pc, lr 323#endif 324 325ENTRY(ftrace_stub) 326.Lftrace_stub: 327 mov pc, lr 328ENDPROC(ftrace_stub) 329 330#endif /* CONFIG_FUNCTION_TRACER */ 331 332/*============================================================================= 333 * SWI handler 334 *----------------------------------------------------------------------------- 335 */ 336 337 .align 5 338ENTRY(vector_swi) 339 sub sp, sp, #S_FRAME_SIZE 340 stmia sp, {r0 - r12} @ Calling r0 - r12 341 ARM( add r8, sp, #S_PC ) 342 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 343 THUMB( mov r8, sp ) 344 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 345 mrs r8, spsr @ called from non-FIQ mode, so ok. 346 str lr, [sp, #S_PC] @ Save calling PC 347 str r8, [sp, #S_PSR] @ Save CPSR 348 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 349 zero_fp 350 351 /* 352 * Get the system call number. 353 */ 354 355#if defined(CONFIG_OABI_COMPAT) 356 357 /* 358 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 359 * value to determine if it is an EABI or an old ABI call. 360 */ 361#ifdef CONFIG_ARM_THUMB 362 tst r8, #PSR_T_BIT 363 movne r10, #0 @ no thumb OABI emulation 364 ldreq r10, [lr, #-4] @ get SWI instruction 365#else 366 ldr r10, [lr, #-4] @ get SWI instruction 367#endif 368#ifdef CONFIG_CPU_ENDIAN_BE8 369 rev r10, r10 @ little endian instruction 370#endif 371 372#elif defined(CONFIG_AEABI) 373 374 /* 375 * Pure EABI user space always put syscall number into scno (r7). 376 */ 377#elif defined(CONFIG_ARM_THUMB) 378 /* Legacy ABI only, possibly thumb mode. */ 379 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs 380 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 381 ldreq scno, [lr, #-4] 382 383#else 384 /* Legacy ABI only. */ 385 ldr scno, [lr, #-4] @ get SWI instruction 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 413local_restart: 414 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 415 stmdb sp!, {r4, r5} @ push fifth and sixth args 416 417#ifdef CONFIG_SECCOMP 418 tst r10, #_TIF_SECCOMP 419 beq 1f 420 mov r0, scno 421 bl __secure_computing 422 add r0, sp, #S_R0 + S_OFF @ pointer to regs 423 ldmia r0, {r0 - r3} @ have to reload r0 - r3 4241: 425#endif 426 427 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 428 bne __sys_trace 429 430 cmp scno, #NR_syscalls @ check upper syscall limit 431 adr lr, BSYM(ret_fast_syscall) @ return address 432 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 433 434 add r1, sp, #S_OFF 4352: mov why, #0 @ no longer a real syscall 436 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 437 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 438 bcs arm_syscall 439 b sys_ni_syscall @ not private func 440ENDPROC(vector_swi) 441 442 /* 443 * This is the really slow path. We're going to be doing 444 * context switches, and waiting for our parent to respond. 445 */ 446__sys_trace: 447 mov r1, scno 448 add r0, sp, #S_OFF 449 bl syscall_trace_enter 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 - r6} @ have to reload r0 - r6 456 stmccia sp, {r4, r5} @ and update the stack args 457 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 458 b 2b 459 460__sys_trace_return: 461 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 462 mov r1, scno 463 mov r0, sp 464 bl syscall_trace_exit 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