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 ldr r1, [tsk, #TI_FLAGS] @ check for syscall tracing 91 mov why, #1 92 tst r1, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 93 beq ret_slow_syscall 94 mov r1, sp 95 mov r0, #1 @ trace exit [IP = 1] 96 bl syscall_trace 97 b ret_slow_syscall 98ENDPROC(ret_from_fork) 99 100 .equ NR_syscalls,0 101#define CALL(x) .equ NR_syscalls,NR_syscalls+1 102#include "calls.S" 103#undef CALL 104#define CALL(x) .long x 105 106#ifdef CONFIG_FUNCTION_TRACER 107/* 108 * When compiling with -pg, gcc inserts a call to the mcount routine at the 109 * start of every function. In mcount, apart from the function's address (in 110 * lr), we need to get hold of the function's caller's address. 111 * 112 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this: 113 * 114 * bl mcount 115 * 116 * These versions have the limitation that in order for the mcount routine to 117 * be able to determine the function's caller's address, an APCS-style frame 118 * pointer (which is set up with something like the code below) is required. 119 * 120 * mov ip, sp 121 * push {fp, ip, lr, pc} 122 * sub fp, ip, #4 123 * 124 * With EABI, these frame pointers are not available unless -mapcs-frame is 125 * specified, and if building as Thumb-2, not even then. 126 * 127 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount, 128 * with call sites like: 129 * 130 * push {lr} 131 * bl __gnu_mcount_nc 132 * 133 * With these compilers, frame pointers are not necessary. 134 * 135 * mcount can be thought of as a function called in the middle of a subroutine 136 * call. As such, it needs to be transparent for both the caller and the 137 * callee: the original lr needs to be restored when leaving mcount, and no 138 * registers should be clobbered. (In the __gnu_mcount_nc implementation, we 139 * clobber the ip register. This is OK because the ARM calling convention 140 * allows it to be clobbered in subroutines and doesn't use it to hold 141 * parameters.) 142 * 143 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0" 144 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see 145 * arch/arm/kernel/ftrace.c). 146 */ 147 148#ifndef CONFIG_OLD_MCOUNT 149#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4)) 150#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0. 151#endif 152#endif 153 154.macro mcount_adjust_addr rd, rn 155 bic \rd, \rn, #1 @ clear the Thumb bit if present 156 sub \rd, \rd, #MCOUNT_INSN_SIZE 157.endm 158 159.macro __mcount suffix 160 mcount_enter 161 ldr r0, =ftrace_trace_function 162 ldr r2, [r0] 163 adr r0, .Lftrace_stub 164 cmp r0, r2 165 bne 1f 166 167#ifdef CONFIG_FUNCTION_GRAPH_TRACER 168 ldr r1, =ftrace_graph_return 169 ldr r2, [r1] 170 cmp r0, r2 171 bne ftrace_graph_caller\suffix 172 173 ldr r1, =ftrace_graph_entry 174 ldr r2, [r1] 175 ldr r0, =ftrace_graph_entry_stub 176 cmp r0, r2 177 bne ftrace_graph_caller\suffix 178#endif 179 180 mcount_exit 181 1821: mcount_get_lr r1 @ lr of instrumented func 183 mcount_adjust_addr r0, lr @ instrumented function 184 adr lr, BSYM(2f) 185 mov pc, r2 1862: mcount_exit 187.endm 188 189.macro __ftrace_caller suffix 190 mcount_enter 191 192 mcount_get_lr r1 @ lr of instrumented func 193 mcount_adjust_addr r0, lr @ instrumented function 194 195 .globl ftrace_call\suffix 196ftrace_call\suffix: 197 bl ftrace_stub 198 199#ifdef CONFIG_FUNCTION_GRAPH_TRACER 200 .globl ftrace_graph_call\suffix 201ftrace_graph_call\suffix: 202 mov r0, r0 203#endif 204 205 mcount_exit 206.endm 207 208.macro __ftrace_graph_caller 209 sub r0, fp, #4 @ &lr of instrumented routine (&parent) 210#ifdef CONFIG_DYNAMIC_FTRACE 211 @ called from __ftrace_caller, saved in mcount_enter 212 ldr r1, [sp, #16] @ instrumented routine (func) 213 mcount_adjust_addr r1, r1 214#else 215 @ called from __mcount, untouched in lr 216 mcount_adjust_addr r1, lr @ instrumented routine (func) 217#endif 218 mov r2, fp @ frame pointer 219 bl prepare_ftrace_return 220 mcount_exit 221.endm 222 223#ifdef CONFIG_OLD_MCOUNT 224/* 225 * mcount 226 */ 227 228.macro mcount_enter 229 stmdb sp!, {r0-r3, lr} 230.endm 231 232.macro mcount_get_lr reg 233 ldr \reg, [fp, #-4] 234.endm 235 236.macro mcount_exit 237 ldr lr, [fp, #-4] 238 ldmia sp!, {r0-r3, pc} 239.endm 240 241ENTRY(mcount) 242#ifdef CONFIG_DYNAMIC_FTRACE 243 stmdb sp!, {lr} 244 ldr lr, [fp, #-4] 245 ldmia sp!, {pc} 246#else 247 __mcount _old 248#endif 249ENDPROC(mcount) 250 251#ifdef CONFIG_DYNAMIC_FTRACE 252ENTRY(ftrace_caller_old) 253 __ftrace_caller _old 254ENDPROC(ftrace_caller_old) 255#endif 256 257#ifdef CONFIG_FUNCTION_GRAPH_TRACER 258ENTRY(ftrace_graph_caller_old) 259 __ftrace_graph_caller 260ENDPROC(ftrace_graph_caller_old) 261#endif 262 263.purgem mcount_enter 264.purgem mcount_get_lr 265.purgem mcount_exit 266#endif 267 268/* 269 * __gnu_mcount_nc 270 */ 271 272.macro mcount_enter 273 stmdb sp!, {r0-r3, lr} 274.endm 275 276.macro mcount_get_lr reg 277 ldr \reg, [sp, #20] 278.endm 279 280.macro mcount_exit 281 ldmia sp!, {r0-r3, ip, lr} 282 mov pc, ip 283.endm 284 285ENTRY(__gnu_mcount_nc) 286#ifdef CONFIG_DYNAMIC_FTRACE 287 mov ip, lr 288 ldmia sp!, {lr} 289 mov pc, ip 290#else 291 __mcount 292#endif 293ENDPROC(__gnu_mcount_nc) 294 295#ifdef CONFIG_DYNAMIC_FTRACE 296ENTRY(ftrace_caller) 297 __ftrace_caller 298ENDPROC(ftrace_caller) 299#endif 300 301#ifdef CONFIG_FUNCTION_GRAPH_TRACER 302ENTRY(ftrace_graph_caller) 303 __ftrace_graph_caller 304ENDPROC(ftrace_graph_caller) 305#endif 306 307.purgem mcount_enter 308.purgem mcount_get_lr 309.purgem mcount_exit 310 311#ifdef CONFIG_FUNCTION_GRAPH_TRACER 312 .globl return_to_handler 313return_to_handler: 314 stmdb sp!, {r0-r3} 315 mov r0, fp @ frame pointer 316 bl ftrace_return_to_handler 317 mov lr, r0 @ r0 has real ret addr 318 ldmia sp!, {r0-r3} 319 mov pc, lr 320#endif 321 322ENTRY(ftrace_stub) 323.Lftrace_stub: 324 mov pc, lr 325ENDPROC(ftrace_stub) 326 327#endif /* CONFIG_FUNCTION_TRACER */ 328 329/*============================================================================= 330 * SWI handler 331 *----------------------------------------------------------------------------- 332 */ 333 334 /* If we're optimising for StrongARM the resulting code won't 335 run on an ARM7 and we can save a couple of instructions. 336 --pb */ 337#ifdef CONFIG_CPU_ARM710 338#define A710(code...) code 339.Larm710bug: 340 ldmia sp, {r0 - lr}^ @ Get calling r0 - lr 341 mov r0, r0 342 add sp, sp, #S_FRAME_SIZE 343 subs pc, lr, #4 344#else 345#define A710(code...) 346#endif 347 348 .align 5 349ENTRY(vector_swi) 350 sub sp, sp, #S_FRAME_SIZE 351 stmia sp, {r0 - r12} @ Calling r0 - r12 352 ARM( add r8, sp, #S_PC ) 353 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 354 THUMB( mov r8, sp ) 355 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 356 mrs r8, spsr @ called from non-FIQ mode, so ok. 357 str lr, [sp, #S_PC] @ Save calling PC 358 str r8, [sp, #S_PSR] @ Save CPSR 359 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 360 zero_fp 361 362 /* 363 * Get the system call number. 364 */ 365 366#if defined(CONFIG_OABI_COMPAT) 367 368 /* 369 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 370 * value to determine if it is an EABI or an old ABI call. 371 */ 372#ifdef CONFIG_ARM_THUMB 373 tst r8, #PSR_T_BIT 374 movne r10, #0 @ no thumb OABI emulation 375 ldreq r10, [lr, #-4] @ get SWI instruction 376#else 377 ldr r10, [lr, #-4] @ get SWI instruction 378 A710( and ip, r10, #0x0f000000 @ check for SWI ) 379 A710( teq ip, #0x0f000000 ) 380 A710( bne .Larm710bug ) 381#endif 382#ifdef CONFIG_CPU_ENDIAN_BE8 383 rev r10, r10 @ little endian instruction 384#endif 385 386#elif defined(CONFIG_AEABI) 387 388 /* 389 * Pure EABI user space always put syscall number into scno (r7). 390 */ 391 A710( ldr ip, [lr, #-4] @ get SWI instruction ) 392 A710( and ip, ip, #0x0f000000 @ check for SWI ) 393 A710( teq ip, #0x0f000000 ) 394 A710( bne .Larm710bug ) 395 396#elif defined(CONFIG_ARM_THUMB) 397 398 /* Legacy ABI only, possibly thumb mode. */ 399 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs 400 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 401 ldreq scno, [lr, #-4] 402 403#else 404 405 /* Legacy ABI only. */ 406 ldr scno, [lr, #-4] @ get SWI instruction 407 A710( and ip, scno, #0x0f000000 @ check for SWI ) 408 A710( teq ip, #0x0f000000 ) 409 A710( bne .Larm710bug ) 410 411#endif 412 413#ifdef CONFIG_ALIGNMENT_TRAP 414 ldr ip, __cr_alignment 415 ldr ip, [ip] 416 mcr p15, 0, ip, c1, c0 @ update control register 417#endif 418 enable_irq 419 420 get_thread_info tsk 421 adr tbl, sys_call_table @ load syscall table pointer 422 423#if defined(CONFIG_OABI_COMPAT) 424 /* 425 * If the swi argument is zero, this is an EABI call and we do nothing. 426 * 427 * If this is an old ABI call, get the syscall number into scno and 428 * get the old ABI syscall table address. 429 */ 430 bics r10, r10, #0xff000000 431 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 432 ldrne tbl, =sys_oabi_call_table 433#elif !defined(CONFIG_AEABI) 434 bic scno, scno, #0xff000000 @ mask off SWI op-code 435 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 436#endif 437 438local_restart: 439 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 440 stmdb sp!, {r4, r5} @ push fifth and sixth args 441 442#ifdef CONFIG_SECCOMP 443 tst r10, #_TIF_SECCOMP 444 bne __sys_trace 445#endif 446 447 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 448 bne __sys_trace 449 450 cmp scno, #NR_syscalls @ check upper syscall limit 451 adr lr, BSYM(ret_fast_syscall) @ return address 452 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 453 454 add r1, sp, #S_OFF 4552: mov why, #0 @ no longer a real syscall 456 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 457 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 458 bcs arm_syscall 459 b sys_ni_syscall @ not private func 460ENDPROC(vector_swi) 461 462 /* 463 * This is the really slow path. We're going to be doing 464 * context switches, and waiting for our parent to respond. 465 */ 466__sys_trace: 467 mov r2, scno 468 add r1, sp, #S_OFF 469 mov r0, #0 @ trace entry [IP = 0] 470 bl syscall_trace 471 472 adr lr, BSYM(__sys_trace_return) @ return address 473 mov scno, r0 @ syscall number (possibly new) 474 add r1, sp, #S_R0 + S_OFF @ pointer to regs 475 cmp scno, #NR_syscalls @ check upper syscall limit 476 ldmccia r1, {r0 - r6} @ have to reload r0 - r6 477 stmccia sp, {r4, r5} @ and update the stack args 478 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 479 b 2b 480 481__sys_trace_return: 482 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 483 mov r2, scno 484 mov r1, sp 485 mov r0, #1 @ trace exit [IP = 1] 486 bl syscall_trace 487 b ret_slow_syscall 488 489 .align 5 490#ifdef CONFIG_ALIGNMENT_TRAP 491 .type __cr_alignment, #object 492__cr_alignment: 493 .word cr_alignment 494#endif 495 .ltorg 496 497/* 498 * This is the syscall table declaration for native ABI syscalls. 499 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 500 */ 501#define ABI(native, compat) native 502#ifdef CONFIG_AEABI 503#define OBSOLETE(syscall) sys_ni_syscall 504#else 505#define OBSOLETE(syscall) syscall 506#endif 507 508 .type sys_call_table, #object 509ENTRY(sys_call_table) 510#include "calls.S" 511#undef ABI 512#undef OBSOLETE 513 514/*============================================================================ 515 * Special system call wrappers 516 */ 517@ r0 = syscall number 518@ r8 = syscall table 519sys_syscall: 520 bic scno, r0, #__NR_OABI_SYSCALL_BASE 521 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 522 cmpne scno, #NR_syscalls @ check range 523 stmloia sp, {r5, r6} @ shuffle args 524 movlo r0, r1 525 movlo r1, r2 526 movlo r2, r3 527 movlo r3, r4 528 ldrlo pc, [tbl, scno, lsl #2] 529 b sys_ni_syscall 530ENDPROC(sys_syscall) 531 532sys_fork_wrapper: 533 add r0, sp, #S_OFF 534 b sys_fork 535ENDPROC(sys_fork_wrapper) 536 537sys_vfork_wrapper: 538 add r0, sp, #S_OFF 539 b sys_vfork 540ENDPROC(sys_vfork_wrapper) 541 542sys_execve_wrapper: 543 add r3, sp, #S_OFF 544 b sys_execve 545ENDPROC(sys_execve_wrapper) 546 547sys_clone_wrapper: 548 add ip, sp, #S_OFF 549 str ip, [sp, #4] 550 b sys_clone 551ENDPROC(sys_clone_wrapper) 552 553sys_sigreturn_wrapper: 554 add r0, sp, #S_OFF 555 mov why, #0 @ prevent syscall restart handling 556 b sys_sigreturn 557ENDPROC(sys_sigreturn_wrapper) 558 559sys_rt_sigreturn_wrapper: 560 add r0, sp, #S_OFF 561 mov why, #0 @ prevent syscall restart handling 562 b sys_rt_sigreturn 563ENDPROC(sys_rt_sigreturn_wrapper) 564 565sys_sigaltstack_wrapper: 566 ldr r2, [sp, #S_OFF + S_SP] 567 b do_sigaltstack 568ENDPROC(sys_sigaltstack_wrapper) 569 570sys_statfs64_wrapper: 571 teq r1, #88 572 moveq r1, #84 573 b sys_statfs64 574ENDPROC(sys_statfs64_wrapper) 575 576sys_fstatfs64_wrapper: 577 teq r1, #88 578 moveq r1, #84 579 b sys_fstatfs64 580ENDPROC(sys_fstatfs64_wrapper) 581 582/* 583 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 584 * offset, we return EINVAL. 585 */ 586sys_mmap2: 587#if PAGE_SHIFT > 12 588 tst r5, #PGOFF_MASK 589 moveq r5, r5, lsr #PAGE_SHIFT - 12 590 streq r5, [sp, #4] 591 beq sys_mmap_pgoff 592 mov r0, #-EINVAL 593 mov pc, lr 594#else 595 str r5, [sp, #4] 596 b sys_mmap_pgoff 597#endif 598ENDPROC(sys_mmap2) 599 600#ifdef CONFIG_OABI_COMPAT 601 602/* 603 * These are syscalls with argument register differences 604 */ 605 606sys_oabi_pread64: 607 stmia sp, {r3, r4} 608 b sys_pread64 609ENDPROC(sys_oabi_pread64) 610 611sys_oabi_pwrite64: 612 stmia sp, {r3, r4} 613 b sys_pwrite64 614ENDPROC(sys_oabi_pwrite64) 615 616sys_oabi_truncate64: 617 mov r3, r2 618 mov r2, r1 619 b sys_truncate64 620ENDPROC(sys_oabi_truncate64) 621 622sys_oabi_ftruncate64: 623 mov r3, r2 624 mov r2, r1 625 b sys_ftruncate64 626ENDPROC(sys_oabi_ftruncate64) 627 628sys_oabi_readahead: 629 str r3, [sp] 630 mov r3, r2 631 mov r2, r1 632 b sys_readahead 633ENDPROC(sys_oabi_readahead) 634 635/* 636 * Let's declare a second syscall table for old ABI binaries 637 * using the compatibility syscall entries. 638 */ 639#define ABI(native, compat) compat 640#define OBSOLETE(syscall) syscall 641 642 .type sys_oabi_call_table, #object 643ENTRY(sys_oabi_call_table) 644#include "calls.S" 645#undef ABI 646#undef OBSOLETE 647 648#endif 649 650