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 mcount_exit 152 1531: mcount_get_lr r1 @ lr of instrumented func 154 mov r0, lr @ instrumented function 155 sub r0, r0, #MCOUNT_INSN_SIZE 156 adr lr, BSYM(2f) 157 mov pc, r2 1582: mcount_exit 159.endm 160 161.macro __ftrace_caller suffix 162 mcount_enter 163 164 mcount_get_lr r1 @ lr of instrumented func 165 mov r0, lr @ instrumented function 166 sub r0, r0, #MCOUNT_INSN_SIZE 167 168 .globl ftrace_call\suffix 169ftrace_call\suffix: 170 bl ftrace_stub 171 172 mcount_exit 173.endm 174 175#ifdef CONFIG_OLD_MCOUNT 176/* 177 * mcount 178 */ 179 180.macro mcount_enter 181 stmdb sp!, {r0-r3, lr} 182.endm 183 184.macro mcount_get_lr reg 185 ldr \reg, [fp, #-4] 186.endm 187 188.macro mcount_exit 189 ldr lr, [fp, #-4] 190 ldmia sp!, {r0-r3, pc} 191.endm 192 193ENTRY(mcount) 194#ifdef CONFIG_DYNAMIC_FTRACE 195 stmdb sp!, {lr} 196 ldr lr, [fp, #-4] 197 ldmia sp!, {pc} 198#else 199 __mcount _old 200#endif 201ENDPROC(mcount) 202 203#ifdef CONFIG_DYNAMIC_FTRACE 204ENTRY(ftrace_caller_old) 205 __ftrace_caller _old 206ENDPROC(ftrace_caller_old) 207#endif 208 209.purgem mcount_enter 210.purgem mcount_get_lr 211.purgem mcount_exit 212#endif 213 214/* 215 * __gnu_mcount_nc 216 */ 217 218.macro mcount_enter 219 stmdb sp!, {r0-r3, lr} 220.endm 221 222.macro mcount_get_lr reg 223 ldr \reg, [sp, #20] 224.endm 225 226.macro mcount_exit 227 ldmia sp!, {r0-r3, ip, lr} 228 mov pc, ip 229.endm 230 231ENTRY(__gnu_mcount_nc) 232#ifdef CONFIG_DYNAMIC_FTRACE 233 mov ip, lr 234 ldmia sp!, {lr} 235 mov pc, ip 236#else 237 __mcount 238#endif 239ENDPROC(__gnu_mcount_nc) 240 241#ifdef CONFIG_DYNAMIC_FTRACE 242ENTRY(ftrace_caller) 243 __ftrace_caller 244ENDPROC(ftrace_caller) 245#endif 246 247.purgem mcount_enter 248.purgem mcount_get_lr 249.purgem mcount_exit 250 251ENTRY(ftrace_stub) 252.Lftrace_stub: 253 mov pc, lr 254ENDPROC(ftrace_stub) 255 256#endif /* CONFIG_FUNCTION_TRACER */ 257 258/*============================================================================= 259 * SWI handler 260 *----------------------------------------------------------------------------- 261 */ 262 263 /* If we're optimising for StrongARM the resulting code won't 264 run on an ARM7 and we can save a couple of instructions. 265 --pb */ 266#ifdef CONFIG_CPU_ARM710 267#define A710(code...) code 268.Larm710bug: 269 ldmia sp, {r0 - lr}^ @ Get calling r0 - lr 270 mov r0, r0 271 add sp, sp, #S_FRAME_SIZE 272 subs pc, lr, #4 273#else 274#define A710(code...) 275#endif 276 277 .align 5 278ENTRY(vector_swi) 279 sub sp, sp, #S_FRAME_SIZE 280 stmia sp, {r0 - r12} @ Calling r0 - r12 281 ARM( add r8, sp, #S_PC ) 282 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 283 THUMB( mov r8, sp ) 284 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 285 mrs r8, spsr @ called from non-FIQ mode, so ok. 286 str lr, [sp, #S_PC] @ Save calling PC 287 str r8, [sp, #S_PSR] @ Save CPSR 288 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 289 zero_fp 290 291 /* 292 * Get the system call number. 293 */ 294 295#if defined(CONFIG_OABI_COMPAT) 296 297 /* 298 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 299 * value to determine if it is an EABI or an old ABI call. 300 */ 301#ifdef CONFIG_ARM_THUMB 302 tst r8, #PSR_T_BIT 303 movne r10, #0 @ no thumb OABI emulation 304 ldreq r10, [lr, #-4] @ get SWI instruction 305#else 306 ldr r10, [lr, #-4] @ get SWI instruction 307 A710( and ip, r10, #0x0f000000 @ check for SWI ) 308 A710( teq ip, #0x0f000000 ) 309 A710( bne .Larm710bug ) 310#endif 311#ifdef CONFIG_CPU_ENDIAN_BE8 312 rev r10, r10 @ little endian instruction 313#endif 314 315#elif defined(CONFIG_AEABI) 316 317 /* 318 * Pure EABI user space always put syscall number into scno (r7). 319 */ 320 A710( ldr ip, [lr, #-4] @ get SWI instruction ) 321 A710( and ip, ip, #0x0f000000 @ check for SWI ) 322 A710( teq ip, #0x0f000000 ) 323 A710( bne .Larm710bug ) 324 325#elif defined(CONFIG_ARM_THUMB) 326 327 /* Legacy ABI only, possibly thumb mode. */ 328 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs 329 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 330 ldreq scno, [lr, #-4] 331 332#else 333 334 /* Legacy ABI only. */ 335 ldr scno, [lr, #-4] @ get SWI instruction 336 A710( and ip, scno, #0x0f000000 @ check for SWI ) 337 A710( teq ip, #0x0f000000 ) 338 A710( bne .Larm710bug ) 339 340#endif 341 342#ifdef CONFIG_ALIGNMENT_TRAP 343 ldr ip, __cr_alignment 344 ldr ip, [ip] 345 mcr p15, 0, ip, c1, c0 @ update control register 346#endif 347 enable_irq 348 349 get_thread_info tsk 350 adr tbl, sys_call_table @ load syscall table pointer 351 352#if defined(CONFIG_OABI_COMPAT) 353 /* 354 * If the swi argument is zero, this is an EABI call and we do nothing. 355 * 356 * If this is an old ABI call, get the syscall number into scno and 357 * get the old ABI syscall table address. 358 */ 359 bics r10, r10, #0xff000000 360 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 361 ldrne tbl, =sys_oabi_call_table 362#elif !defined(CONFIG_AEABI) 363 bic scno, scno, #0xff000000 @ mask off SWI op-code 364 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 365#endif 366 367 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 368 stmdb sp!, {r4, r5} @ push fifth and sixth args 369 370#ifdef CONFIG_SECCOMP 371 tst r10, #_TIF_SECCOMP 372 beq 1f 373 mov r0, scno 374 bl __secure_computing 375 add r0, sp, #S_R0 + S_OFF @ pointer to regs 376 ldmia r0, {r0 - r3} @ have to reload r0 - r3 3771: 378#endif 379 380 tst r10, #_TIF_SYSCALL_TRACE @ are we tracing syscalls? 381 bne __sys_trace 382 383 cmp scno, #NR_syscalls @ check upper syscall limit 384 adr lr, BSYM(ret_fast_syscall) @ return address 385 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 386 387 add r1, sp, #S_OFF 3882: mov why, #0 @ no longer a real syscall 389 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 390 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 391 bcs arm_syscall 392 b sys_ni_syscall @ not private func 393ENDPROC(vector_swi) 394 395 /* 396 * This is the really slow path. We're going to be doing 397 * context switches, and waiting for our parent to respond. 398 */ 399__sys_trace: 400 mov r2, scno 401 add r1, sp, #S_OFF 402 mov r0, #0 @ trace entry [IP = 0] 403 bl syscall_trace 404 405 adr lr, BSYM(__sys_trace_return) @ return address 406 mov scno, r0 @ syscall number (possibly new) 407 add r1, sp, #S_R0 + S_OFF @ pointer to regs 408 cmp scno, #NR_syscalls @ check upper syscall limit 409 ldmccia r1, {r0 - r3} @ have to reload r0 - r3 410 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 411 b 2b 412 413__sys_trace_return: 414 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 415 mov r2, scno 416 mov r1, sp 417 mov r0, #1 @ trace exit [IP = 1] 418 bl syscall_trace 419 b ret_slow_syscall 420 421 .align 5 422#ifdef CONFIG_ALIGNMENT_TRAP 423 .type __cr_alignment, #object 424__cr_alignment: 425 .word cr_alignment 426#endif 427 .ltorg 428 429/* 430 * This is the syscall table declaration for native ABI syscalls. 431 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 432 */ 433#define ABI(native, compat) native 434#ifdef CONFIG_AEABI 435#define OBSOLETE(syscall) sys_ni_syscall 436#else 437#define OBSOLETE(syscall) syscall 438#endif 439 440 .type sys_call_table, #object 441ENTRY(sys_call_table) 442#include "calls.S" 443#undef ABI 444#undef OBSOLETE 445 446/*============================================================================ 447 * Special system call wrappers 448 */ 449@ r0 = syscall number 450@ r8 = syscall table 451sys_syscall: 452 bic scno, r0, #__NR_OABI_SYSCALL_BASE 453 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 454 cmpne scno, #NR_syscalls @ check range 455 stmloia sp, {r5, r6} @ shuffle args 456 movlo r0, r1 457 movlo r1, r2 458 movlo r2, r3 459 movlo r3, r4 460 ldrlo pc, [tbl, scno, lsl #2] 461 b sys_ni_syscall 462ENDPROC(sys_syscall) 463 464sys_fork_wrapper: 465 add r0, sp, #S_OFF 466 b sys_fork 467ENDPROC(sys_fork_wrapper) 468 469sys_vfork_wrapper: 470 add r0, sp, #S_OFF 471 b sys_vfork 472ENDPROC(sys_vfork_wrapper) 473 474sys_execve_wrapper: 475 add r3, sp, #S_OFF 476 b sys_execve 477ENDPROC(sys_execve_wrapper) 478 479sys_clone_wrapper: 480 add ip, sp, #S_OFF 481 str ip, [sp, #4] 482 b sys_clone 483ENDPROC(sys_clone_wrapper) 484 485sys_sigreturn_wrapper: 486 add r0, sp, #S_OFF 487 mov why, #0 @ prevent syscall restart handling 488 b sys_sigreturn 489ENDPROC(sys_sigreturn_wrapper) 490 491sys_rt_sigreturn_wrapper: 492 add r0, sp, #S_OFF 493 mov why, #0 @ prevent syscall restart handling 494 b sys_rt_sigreturn 495ENDPROC(sys_rt_sigreturn_wrapper) 496 497sys_sigaltstack_wrapper: 498 ldr r2, [sp, #S_OFF + S_SP] 499 b do_sigaltstack 500ENDPROC(sys_sigaltstack_wrapper) 501 502sys_statfs64_wrapper: 503 teq r1, #88 504 moveq r1, #84 505 b sys_statfs64 506ENDPROC(sys_statfs64_wrapper) 507 508sys_fstatfs64_wrapper: 509 teq r1, #88 510 moveq r1, #84 511 b sys_fstatfs64 512ENDPROC(sys_fstatfs64_wrapper) 513 514/* 515 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 516 * offset, we return EINVAL. 517 */ 518sys_mmap2: 519#if PAGE_SHIFT > 12 520 tst r5, #PGOFF_MASK 521 moveq r5, r5, lsr #PAGE_SHIFT - 12 522 streq r5, [sp, #4] 523 beq sys_mmap_pgoff 524 mov r0, #-EINVAL 525 mov pc, lr 526#else 527 str r5, [sp, #4] 528 b sys_mmap_pgoff 529#endif 530ENDPROC(sys_mmap2) 531 532#ifdef CONFIG_OABI_COMPAT 533 534/* 535 * These are syscalls with argument register differences 536 */ 537 538sys_oabi_pread64: 539 stmia sp, {r3, r4} 540 b sys_pread64 541ENDPROC(sys_oabi_pread64) 542 543sys_oabi_pwrite64: 544 stmia sp, {r3, r4} 545 b sys_pwrite64 546ENDPROC(sys_oabi_pwrite64) 547 548sys_oabi_truncate64: 549 mov r3, r2 550 mov r2, r1 551 b sys_truncate64 552ENDPROC(sys_oabi_truncate64) 553 554sys_oabi_ftruncate64: 555 mov r3, r2 556 mov r2, r1 557 b sys_ftruncate64 558ENDPROC(sys_oabi_ftruncate64) 559 560sys_oabi_readahead: 561 str r3, [sp] 562 mov r3, r2 563 mov r2, r1 564 b sys_readahead 565ENDPROC(sys_oabi_readahead) 566 567/* 568 * Let's declare a second syscall table for old ABI binaries 569 * using the compatibility syscall entries. 570 */ 571#define ABI(native, compat) compat 572#define OBSOLETE(syscall) syscall 573 574 .type sys_oabi_call_table, #object 575ENTRY(sys_oabi_call_table) 576#include "calls.S" 577#undef ABI 578#undef OBSOLETE 579 580#endif 581 582