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 asm_trace_hardirqs_on 39 40 /* perform architecture specific actions before user return */ 41 arch_ret_to_user r1, lr 42 ct_user_enter 43 44 restore_user_regs fast = 1, offset = S_OFF 45 UNWIND(.fnend ) 46 47/* 48 * Ok, we need to do extra processing, enter the slow path. 49 */ 50fast_work_pending: 51 str r0, [sp, #S_R0+S_OFF]! @ returned r0 52work_pending: 53 mov r0, sp @ 'regs' 54 mov r2, why @ 'syscall' 55 bl do_work_pending 56 cmp r0, #0 57 beq no_work_pending 58 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) 59 ldmia sp, {r0 - r6} @ have to reload r0 - r6 60 b local_restart @ ... and off we go 61 62/* 63 * "slow" syscall return path. "why" tells us if this was a real syscall. 64 */ 65ENTRY(ret_to_user) 66ret_slow_syscall: 67 disable_irq @ disable interrupts 68ENTRY(ret_to_user_from_irq) 69 ldr r1, [tsk, #TI_FLAGS] 70 tst r1, #_TIF_WORK_MASK 71 bne work_pending 72no_work_pending: 73 asm_trace_hardirqs_on 74 75 /* perform architecture specific actions before user return */ 76 arch_ret_to_user r1, lr 77 ct_user_enter save = 0 78 79 restore_user_regs fast = 0, offset = 0 80ENDPROC(ret_to_user_from_irq) 81ENDPROC(ret_to_user) 82 83/* 84 * This is how we return from a fork. 85 */ 86ENTRY(ret_from_fork) 87 bl schedule_tail 88 cmp r5, #0 89 movne r0, r4 90 adrne lr, BSYM(1f) 91 movne pc, r5 921: get_thread_info tsk 93 b ret_slow_syscall 94ENDPROC(ret_from_fork) 95 96 .equ NR_syscalls,0 97#define CALL(x) .equ NR_syscalls,NR_syscalls+1 98#include "calls.S" 99 100/* 101 * Ensure that the system call table is equal to __NR_syscalls, 102 * which is the value the rest of the system sees 103 */ 104.ifne NR_syscalls - __NR_syscalls 105.error "__NR_syscalls is not equal to the size of the syscall table" 106.endif 107 108#undef CALL 109#define CALL(x) .long x 110 111#ifdef CONFIG_FUNCTION_TRACER 112/* 113 * When compiling with -pg, gcc inserts a call to the mcount routine at the 114 * start of every function. In mcount, apart from the function's address (in 115 * lr), we need to get hold of the function's caller's address. 116 * 117 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this: 118 * 119 * bl mcount 120 * 121 * These versions have the limitation that in order for the mcount routine to 122 * be able to determine the function's caller's address, an APCS-style frame 123 * pointer (which is set up with something like the code below) is required. 124 * 125 * mov ip, sp 126 * push {fp, ip, lr, pc} 127 * sub fp, ip, #4 128 * 129 * With EABI, these frame pointers are not available unless -mapcs-frame is 130 * specified, and if building as Thumb-2, not even then. 131 * 132 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount, 133 * with call sites like: 134 * 135 * push {lr} 136 * bl __gnu_mcount_nc 137 * 138 * With these compilers, frame pointers are not necessary. 139 * 140 * mcount can be thought of as a function called in the middle of a subroutine 141 * call. As such, it needs to be transparent for both the caller and the 142 * callee: the original lr needs to be restored when leaving mcount, and no 143 * registers should be clobbered. (In the __gnu_mcount_nc implementation, we 144 * clobber the ip register. This is OK because the ARM calling convention 145 * allows it to be clobbered in subroutines and doesn't use it to hold 146 * parameters.) 147 * 148 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0" 149 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see 150 * arch/arm/kernel/ftrace.c). 151 */ 152 153#ifndef CONFIG_OLD_MCOUNT 154#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4)) 155#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0. 156#endif 157#endif 158 159.macro mcount_adjust_addr rd, rn 160 bic \rd, \rn, #1 @ clear the Thumb bit if present 161 sub \rd, \rd, #MCOUNT_INSN_SIZE 162.endm 163 164.macro __mcount suffix 165 mcount_enter 166 ldr r0, =ftrace_trace_function 167 ldr r2, [r0] 168 adr r0, .Lftrace_stub 169 cmp r0, r2 170 bne 1f 171 172#ifdef CONFIG_FUNCTION_GRAPH_TRACER 173 ldr r1, =ftrace_graph_return 174 ldr r2, [r1] 175 cmp r0, r2 176 bne ftrace_graph_caller\suffix 177 178 ldr r1, =ftrace_graph_entry 179 ldr r2, [r1] 180 ldr r0, =ftrace_graph_entry_stub 181 cmp r0, r2 182 bne ftrace_graph_caller\suffix 183#endif 184 185 mcount_exit 186 1871: mcount_get_lr r1 @ lr of instrumented func 188 mcount_adjust_addr r0, lr @ instrumented function 189 adr lr, BSYM(2f) 190 mov pc, r2 1912: mcount_exit 192.endm 193 194.macro __ftrace_caller suffix 195 mcount_enter 196 197 mcount_get_lr r1 @ lr of instrumented func 198 mcount_adjust_addr r0, lr @ instrumented function 199 200 .globl ftrace_call\suffix 201ftrace_call\suffix: 202 bl ftrace_stub 203 204#ifdef CONFIG_FUNCTION_GRAPH_TRACER 205 .globl ftrace_graph_call\suffix 206ftrace_graph_call\suffix: 207 mov r0, r0 208#endif 209 210 mcount_exit 211.endm 212 213.macro __ftrace_graph_caller 214 sub r0, fp, #4 @ &lr of instrumented routine (&parent) 215#ifdef CONFIG_DYNAMIC_FTRACE 216 @ called from __ftrace_caller, saved in mcount_enter 217 ldr r1, [sp, #16] @ instrumented routine (func) 218 mcount_adjust_addr r1, r1 219#else 220 @ called from __mcount, untouched in lr 221 mcount_adjust_addr r1, lr @ instrumented routine (func) 222#endif 223 mov r2, fp @ frame pointer 224 bl prepare_ftrace_return 225 mcount_exit 226.endm 227 228#ifdef CONFIG_OLD_MCOUNT 229/* 230 * mcount 231 */ 232 233.macro mcount_enter 234 stmdb sp!, {r0-r3, lr} 235.endm 236 237.macro mcount_get_lr reg 238 ldr \reg, [fp, #-4] 239.endm 240 241.macro mcount_exit 242 ldr lr, [fp, #-4] 243 ldmia sp!, {r0-r3, pc} 244.endm 245 246ENTRY(mcount) 247#ifdef CONFIG_DYNAMIC_FTRACE 248 stmdb sp!, {lr} 249 ldr lr, [fp, #-4] 250 ldmia sp!, {pc} 251#else 252 __mcount _old 253#endif 254ENDPROC(mcount) 255 256#ifdef CONFIG_DYNAMIC_FTRACE 257ENTRY(ftrace_caller_old) 258 __ftrace_caller _old 259ENDPROC(ftrace_caller_old) 260#endif 261 262#ifdef CONFIG_FUNCTION_GRAPH_TRACER 263ENTRY(ftrace_graph_caller_old) 264 __ftrace_graph_caller 265ENDPROC(ftrace_graph_caller_old) 266#endif 267 268.purgem mcount_enter 269.purgem mcount_get_lr 270.purgem mcount_exit 271#endif 272 273/* 274 * __gnu_mcount_nc 275 */ 276 277.macro mcount_enter 278/* 279 * This pad compensates for the push {lr} at the call site. Note that we are 280 * unable to unwind through a function which does not otherwise save its lr. 281 */ 282 UNWIND(.pad #4) 283 stmdb sp!, {r0-r3, lr} 284 UNWIND(.save {r0-r3, lr}) 285.endm 286 287.macro mcount_get_lr reg 288 ldr \reg, [sp, #20] 289.endm 290 291.macro mcount_exit 292 ldmia sp!, {r0-r3, ip, lr} 293 mov pc, ip 294.endm 295 296ENTRY(__gnu_mcount_nc) 297UNWIND(.fnstart) 298#ifdef CONFIG_DYNAMIC_FTRACE 299 mov ip, lr 300 ldmia sp!, {lr} 301 mov pc, ip 302#else 303 __mcount 304#endif 305UNWIND(.fnend) 306ENDPROC(__gnu_mcount_nc) 307 308#ifdef CONFIG_DYNAMIC_FTRACE 309ENTRY(ftrace_caller) 310UNWIND(.fnstart) 311 __ftrace_caller 312UNWIND(.fnend) 313ENDPROC(ftrace_caller) 314#endif 315 316#ifdef CONFIG_FUNCTION_GRAPH_TRACER 317ENTRY(ftrace_graph_caller) 318UNWIND(.fnstart) 319 __ftrace_graph_caller 320UNWIND(.fnend) 321ENDPROC(ftrace_graph_caller) 322#endif 323 324.purgem mcount_enter 325.purgem mcount_get_lr 326.purgem mcount_exit 327 328#ifdef CONFIG_FUNCTION_GRAPH_TRACER 329 .globl return_to_handler 330return_to_handler: 331 stmdb sp!, {r0-r3} 332 mov r0, fp @ frame pointer 333 bl ftrace_return_to_handler 334 mov lr, r0 @ r0 has real ret addr 335 ldmia sp!, {r0-r3} 336 mov pc, lr 337#endif 338 339ENTRY(ftrace_stub) 340.Lftrace_stub: 341 mov pc, lr 342ENDPROC(ftrace_stub) 343 344#endif /* CONFIG_FUNCTION_TRACER */ 345 346/*============================================================================= 347 * SWI handler 348 *----------------------------------------------------------------------------- 349 */ 350 351 .align 5 352ENTRY(vector_swi) 353#ifdef CONFIG_CPU_V7M 354 v7m_exception_entry 355#else 356 sub sp, sp, #S_FRAME_SIZE 357 stmia sp, {r0 - r12} @ Calling r0 - r12 358 ARM( add r8, sp, #S_PC ) 359 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 360 THUMB( mov r8, sp ) 361 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 362 mrs r8, spsr @ called from non-FIQ mode, so ok. 363 str lr, [sp, #S_PC] @ Save calling PC 364 str r8, [sp, #S_PSR] @ Save CPSR 365 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 366#endif 367 zero_fp 368 369#ifdef CONFIG_ALIGNMENT_TRAP 370 ldr ip, __cr_alignment 371 ldr ip, [ip] 372 mcr p15, 0, ip, c1, c0 @ update control register 373#endif 374 375 enable_irq 376 ct_user_exit 377 get_thread_info tsk 378 379 /* 380 * Get the system call number. 381 */ 382 383#if defined(CONFIG_OABI_COMPAT) 384 385 /* 386 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 387 * value to determine if it is an EABI or an old ABI call. 388 */ 389#ifdef CONFIG_ARM_THUMB 390 tst r8, #PSR_T_BIT 391 movne r10, #0 @ no thumb OABI emulation 392 USER( ldreq r10, [lr, #-4] ) @ get SWI instruction 393#else 394 USER( ldr r10, [lr, #-4] ) @ get SWI instruction 395#endif 396 ARM_BE8(rev r10, r10) @ little endian instruction 397 398#elif defined(CONFIG_AEABI) 399 400 /* 401 * Pure EABI user space always put syscall number into scno (r7). 402 */ 403#elif defined(CONFIG_ARM_THUMB) 404 /* Legacy ABI only, possibly thumb mode. */ 405 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs 406 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 407 USER( ldreq scno, [lr, #-4] ) 408 409#else 410 /* Legacy ABI only. */ 411 USER( ldr scno, [lr, #-4] ) @ get SWI instruction 412#endif 413 414 adr tbl, sys_call_table @ load syscall table pointer 415 416#if defined(CONFIG_OABI_COMPAT) 417 /* 418 * If the swi argument is zero, this is an EABI call and we do nothing. 419 * 420 * If this is an old ABI call, get the syscall number into scno and 421 * get the old ABI syscall table address. 422 */ 423 bics r10, r10, #0xff000000 424 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 425 ldrne tbl, =sys_oabi_call_table 426#elif !defined(CONFIG_AEABI) 427 bic scno, scno, #0xff000000 @ mask off SWI op-code 428 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 429#endif 430 431local_restart: 432 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 433 stmdb sp!, {r4, r5} @ push fifth and sixth args 434 435 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 436 bne __sys_trace 437 438 cmp scno, #NR_syscalls @ check upper syscall limit 439 adr lr, BSYM(ret_fast_syscall) @ return address 440 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 441 442 add r1, sp, #S_OFF 4432: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 444 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 445 bcs arm_syscall 446 mov why, #0 @ no longer a real syscall 447 b sys_ni_syscall @ not private func 448 449#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 450 /* 451 * We failed to handle a fault trying to access the page 452 * containing the swi instruction, but we're not really in a 453 * position to return -EFAULT. Instead, return back to the 454 * instruction and re-enter the user fault handling path trying 455 * to page it in. This will likely result in sending SEGV to the 456 * current task. 457 */ 4589001: 459 sub lr, lr, #4 460 str lr, [sp, #S_PC] 461 b ret_fast_syscall 462#endif 463ENDPROC(vector_swi) 464 465 /* 466 * This is the really slow path. We're going to be doing 467 * context switches, and waiting for our parent to respond. 468 */ 469__sys_trace: 470 mov r1, scno 471 add r0, sp, #S_OFF 472 bl syscall_trace_enter 473 474 adr lr, BSYM(__sys_trace_return) @ return address 475 mov scno, r0 @ syscall number (possibly new) 476 add r1, sp, #S_R0 + S_OFF @ pointer to regs 477 cmp scno, #NR_syscalls @ check upper syscall limit 478 ldmccia r1, {r0 - r6} @ have to reload r0 - r6 479 stmccia sp, {r4, r5} @ and update the stack args 480 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 481 cmp scno, #-1 @ skip the syscall? 482 bne 2b 483 add sp, sp, #S_OFF @ restore stack 484 b ret_slow_syscall 485 486__sys_trace_return: 487 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 488 mov r0, sp 489 bl syscall_trace_exit 490 b ret_slow_syscall 491 492 .align 5 493#ifdef CONFIG_ALIGNMENT_TRAP 494 .type __cr_alignment, #object 495__cr_alignment: 496 .word cr_alignment 497#endif 498 .ltorg 499 500/* 501 * This is the syscall table declaration for native ABI syscalls. 502 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 503 */ 504#define ABI(native, compat) native 505#ifdef CONFIG_AEABI 506#define OBSOLETE(syscall) sys_ni_syscall 507#else 508#define OBSOLETE(syscall) syscall 509#endif 510 511 .type sys_call_table, #object 512ENTRY(sys_call_table) 513#include "calls.S" 514#undef ABI 515#undef OBSOLETE 516 517/*============================================================================ 518 * Special system call wrappers 519 */ 520@ r0 = syscall number 521@ r8 = syscall table 522sys_syscall: 523 bic scno, r0, #__NR_OABI_SYSCALL_BASE 524 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 525 cmpne scno, #NR_syscalls @ check range 526 stmloia sp, {r5, r6} @ shuffle args 527 movlo r0, r1 528 movlo r1, r2 529 movlo r2, r3 530 movlo r3, r4 531 ldrlo pc, [tbl, scno, lsl #2] 532 b sys_ni_syscall 533ENDPROC(sys_syscall) 534 535sys_sigreturn_wrapper: 536 add r0, sp, #S_OFF 537 mov why, #0 @ prevent syscall restart handling 538 b sys_sigreturn 539ENDPROC(sys_sigreturn_wrapper) 540 541sys_rt_sigreturn_wrapper: 542 add r0, sp, #S_OFF 543 mov why, #0 @ prevent syscall restart handling 544 b sys_rt_sigreturn 545ENDPROC(sys_rt_sigreturn_wrapper) 546 547sys_statfs64_wrapper: 548 teq r1, #88 549 moveq r1, #84 550 b sys_statfs64 551ENDPROC(sys_statfs64_wrapper) 552 553sys_fstatfs64_wrapper: 554 teq r1, #88 555 moveq r1, #84 556 b sys_fstatfs64 557ENDPROC(sys_fstatfs64_wrapper) 558 559/* 560 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 561 * offset, we return EINVAL. 562 */ 563sys_mmap2: 564#if PAGE_SHIFT > 12 565 tst r5, #PGOFF_MASK 566 moveq r5, r5, lsr #PAGE_SHIFT - 12 567 streq r5, [sp, #4] 568 beq sys_mmap_pgoff 569 mov r0, #-EINVAL 570 mov pc, lr 571#else 572 str r5, [sp, #4] 573 b sys_mmap_pgoff 574#endif 575ENDPROC(sys_mmap2) 576 577#ifdef CONFIG_OABI_COMPAT 578 579/* 580 * These are syscalls with argument register differences 581 */ 582 583sys_oabi_pread64: 584 stmia sp, {r3, r4} 585 b sys_pread64 586ENDPROC(sys_oabi_pread64) 587 588sys_oabi_pwrite64: 589 stmia sp, {r3, r4} 590 b sys_pwrite64 591ENDPROC(sys_oabi_pwrite64) 592 593sys_oabi_truncate64: 594 mov r3, r2 595 mov r2, r1 596 b sys_truncate64 597ENDPROC(sys_oabi_truncate64) 598 599sys_oabi_ftruncate64: 600 mov r3, r2 601 mov r2, r1 602 b sys_ftruncate64 603ENDPROC(sys_oabi_ftruncate64) 604 605sys_oabi_readahead: 606 str r3, [sp] 607 mov r3, r2 608 mov r2, r1 609 b sys_readahead 610ENDPROC(sys_oabi_readahead) 611 612/* 613 * Let's declare a second syscall table for old ABI binaries 614 * using the compatibility syscall entries. 615 */ 616#define ABI(native, compat) compat 617#define OBSOLETE(syscall) syscall 618 619 .type sys_oabi_call_table, #object 620ENTRY(sys_oabi_call_table) 621#include "calls.S" 622#undef ABI 623#undef OBSOLETE 624 625#endif 626 627