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#ifdef CONFIG_DYNAMIC_FTRACE 145ENTRY(__gnu_mcount_nc) 146 mov ip, lr 147 ldmia sp!, {lr} 148 mov pc, ip 149ENDPROC(__gnu_mcount_nc) 150 151ENTRY(ftrace_caller) 152 stmdb sp!, {r0-r3, lr} 153 mov r0, lr 154 sub r0, r0, #MCOUNT_INSN_SIZE 155 ldr r1, [sp, #20] 156 157 .global ftrace_call 158ftrace_call: 159 bl ftrace_stub 160 ldmia sp!, {r0-r3, ip, lr} 161 mov pc, ip 162ENDPROC(ftrace_caller) 163 164#ifdef CONFIG_OLD_MCOUNT 165ENTRY(mcount) 166 stmdb sp!, {lr} 167 ldr lr, [fp, #-4] 168 ldmia sp!, {pc} 169ENDPROC(mcount) 170 171ENTRY(ftrace_caller_old) 172 stmdb sp!, {r0-r3, lr} 173 ldr r1, [fp, #-4] 174 mov r0, lr 175 sub r0, r0, #MCOUNT_INSN_SIZE 176 177 .globl ftrace_call_old 178ftrace_call_old: 179 bl ftrace_stub 180 ldr lr, [fp, #-4] @ restore lr 181 ldmia sp!, {r0-r3, pc} 182ENDPROC(ftrace_caller_old) 183#endif 184 185#else 186 187ENTRY(__gnu_mcount_nc) 188 stmdb sp!, {r0-r3, lr} 189 ldr r0, =ftrace_trace_function 190 ldr r2, [r0] 191 adr r0, .Lftrace_stub 192 cmp r0, r2 193 bne gnu_trace 194 ldmia sp!, {r0-r3, ip, lr} 195 mov pc, ip 196 197gnu_trace: 198 ldr r1, [sp, #20] @ lr of instrumented routine 199 mov r0, lr 200 sub r0, r0, #MCOUNT_INSN_SIZE 201 adr lr, BSYM(1f) 202 mov pc, r2 2031: 204 ldmia sp!, {r0-r3, ip, lr} 205 mov pc, ip 206ENDPROC(__gnu_mcount_nc) 207 208#ifdef CONFIG_OLD_MCOUNT 209/* 210 * This is under an ifdef in order to force link-time errors for people trying 211 * to build with !FRAME_POINTER with a GCC which doesn't use the new-style 212 * mcount. 213 */ 214ENTRY(mcount) 215 stmdb sp!, {r0-r3, lr} 216 ldr r0, =ftrace_trace_function 217 ldr r2, [r0] 218 adr r0, ftrace_stub 219 cmp r0, r2 220 bne trace 221 ldr lr, [fp, #-4] @ restore lr 222 ldmia sp!, {r0-r3, pc} 223 224trace: 225 ldr r1, [fp, #-4] @ lr of instrumented routine 226 mov r0, lr 227 sub r0, r0, #MCOUNT_INSN_SIZE 228 mov lr, pc 229 mov pc, r2 230 ldr lr, [fp, #-4] @ restore lr 231 ldmia sp!, {r0-r3, pc} 232ENDPROC(mcount) 233#endif 234 235#endif /* CONFIG_DYNAMIC_FTRACE */ 236 237ENTRY(ftrace_stub) 238.Lftrace_stub: 239 mov pc, lr 240ENDPROC(ftrace_stub) 241 242#endif /* CONFIG_FUNCTION_TRACER */ 243 244/*============================================================================= 245 * SWI handler 246 *----------------------------------------------------------------------------- 247 */ 248 249 /* If we're optimising for StrongARM the resulting code won't 250 run on an ARM7 and we can save a couple of instructions. 251 --pb */ 252#ifdef CONFIG_CPU_ARM710 253#define A710(code...) code 254.Larm710bug: 255 ldmia sp, {r0 - lr}^ @ Get calling r0 - lr 256 mov r0, r0 257 add sp, sp, #S_FRAME_SIZE 258 subs pc, lr, #4 259#else 260#define A710(code...) 261#endif 262 263 .align 5 264ENTRY(vector_swi) 265 sub sp, sp, #S_FRAME_SIZE 266 stmia sp, {r0 - r12} @ Calling r0 - r12 267 ARM( add r8, sp, #S_PC ) 268 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 269 THUMB( mov r8, sp ) 270 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 271 mrs r8, spsr @ called from non-FIQ mode, so ok. 272 str lr, [sp, #S_PC] @ Save calling PC 273 str r8, [sp, #S_PSR] @ Save CPSR 274 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 275 zero_fp 276 277 /* 278 * Get the system call number. 279 */ 280 281#if defined(CONFIG_OABI_COMPAT) 282 283 /* 284 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 285 * value to determine if it is an EABI or an old ABI call. 286 */ 287#ifdef CONFIG_ARM_THUMB 288 tst r8, #PSR_T_BIT 289 movne r10, #0 @ no thumb OABI emulation 290 ldreq r10, [lr, #-4] @ get SWI instruction 291#else 292 ldr r10, [lr, #-4] @ get SWI instruction 293 A710( and ip, r10, #0x0f000000 @ check for SWI ) 294 A710( teq ip, #0x0f000000 ) 295 A710( bne .Larm710bug ) 296#endif 297#ifdef CONFIG_CPU_ENDIAN_BE8 298 rev r10, r10 @ little endian instruction 299#endif 300 301#elif defined(CONFIG_AEABI) 302 303 /* 304 * Pure EABI user space always put syscall number into scno (r7). 305 */ 306 A710( ldr ip, [lr, #-4] @ get SWI instruction ) 307 A710( and ip, ip, #0x0f000000 @ check for SWI ) 308 A710( teq ip, #0x0f000000 ) 309 A710( bne .Larm710bug ) 310 311#elif defined(CONFIG_ARM_THUMB) 312 313 /* Legacy ABI only, possibly thumb mode. */ 314 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs 315 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 316 ldreq scno, [lr, #-4] 317 318#else 319 320 /* Legacy ABI only. */ 321 ldr scno, [lr, #-4] @ get SWI instruction 322 A710( and ip, scno, #0x0f000000 @ check for SWI ) 323 A710( teq ip, #0x0f000000 ) 324 A710( bne .Larm710bug ) 325 326#endif 327 328#ifdef CONFIG_ALIGNMENT_TRAP 329 ldr ip, __cr_alignment 330 ldr ip, [ip] 331 mcr p15, 0, ip, c1, c0 @ update control register 332#endif 333 enable_irq 334 335 get_thread_info tsk 336 adr tbl, sys_call_table @ load syscall table pointer 337 338#if defined(CONFIG_OABI_COMPAT) 339 /* 340 * If the swi argument is zero, this is an EABI call and we do nothing. 341 * 342 * If this is an old ABI call, get the syscall number into scno and 343 * get the old ABI syscall table address. 344 */ 345 bics r10, r10, #0xff000000 346 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 347 ldrne tbl, =sys_oabi_call_table 348#elif !defined(CONFIG_AEABI) 349 bic scno, scno, #0xff000000 @ mask off SWI op-code 350 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 351#endif 352 353 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 354 stmdb sp!, {r4, r5} @ push fifth and sixth args 355 356#ifdef CONFIG_SECCOMP 357 tst r10, #_TIF_SECCOMP 358 beq 1f 359 mov r0, scno 360 bl __secure_computing 361 add r0, sp, #S_R0 + S_OFF @ pointer to regs 362 ldmia r0, {r0 - r3} @ have to reload r0 - r3 3631: 364#endif 365 366 tst r10, #_TIF_SYSCALL_TRACE @ are we tracing syscalls? 367 bne __sys_trace 368 369 cmp scno, #NR_syscalls @ check upper syscall limit 370 adr lr, BSYM(ret_fast_syscall) @ return address 371 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 372 373 add r1, sp, #S_OFF 3742: mov why, #0 @ no longer a real syscall 375 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 376 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 377 bcs arm_syscall 378 b sys_ni_syscall @ not private func 379ENDPROC(vector_swi) 380 381 /* 382 * This is the really slow path. We're going to be doing 383 * context switches, and waiting for our parent to respond. 384 */ 385__sys_trace: 386 mov r2, scno 387 add r1, sp, #S_OFF 388 mov r0, #0 @ trace entry [IP = 0] 389 bl syscall_trace 390 391 adr lr, BSYM(__sys_trace_return) @ return address 392 mov scno, r0 @ syscall number (possibly new) 393 add r1, sp, #S_R0 + S_OFF @ pointer to regs 394 cmp scno, #NR_syscalls @ check upper syscall limit 395 ldmccia r1, {r0 - r3} @ have to reload r0 - r3 396 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 397 b 2b 398 399__sys_trace_return: 400 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 401 mov r2, scno 402 mov r1, sp 403 mov r0, #1 @ trace exit [IP = 1] 404 bl syscall_trace 405 b ret_slow_syscall 406 407 .align 5 408#ifdef CONFIG_ALIGNMENT_TRAP 409 .type __cr_alignment, #object 410__cr_alignment: 411 .word cr_alignment 412#endif 413 .ltorg 414 415/* 416 * This is the syscall table declaration for native ABI syscalls. 417 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 418 */ 419#define ABI(native, compat) native 420#ifdef CONFIG_AEABI 421#define OBSOLETE(syscall) sys_ni_syscall 422#else 423#define OBSOLETE(syscall) syscall 424#endif 425 426 .type sys_call_table, #object 427ENTRY(sys_call_table) 428#include "calls.S" 429#undef ABI 430#undef OBSOLETE 431 432/*============================================================================ 433 * Special system call wrappers 434 */ 435@ r0 = syscall number 436@ r8 = syscall table 437sys_syscall: 438 bic scno, r0, #__NR_OABI_SYSCALL_BASE 439 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 440 cmpne scno, #NR_syscalls @ check range 441 stmloia sp, {r5, r6} @ shuffle args 442 movlo r0, r1 443 movlo r1, r2 444 movlo r2, r3 445 movlo r3, r4 446 ldrlo pc, [tbl, scno, lsl #2] 447 b sys_ni_syscall 448ENDPROC(sys_syscall) 449 450sys_fork_wrapper: 451 add r0, sp, #S_OFF 452 b sys_fork 453ENDPROC(sys_fork_wrapper) 454 455sys_vfork_wrapper: 456 add r0, sp, #S_OFF 457 b sys_vfork 458ENDPROC(sys_vfork_wrapper) 459 460sys_execve_wrapper: 461 add r3, sp, #S_OFF 462 b sys_execve 463ENDPROC(sys_execve_wrapper) 464 465sys_clone_wrapper: 466 add ip, sp, #S_OFF 467 str ip, [sp, #4] 468 b sys_clone 469ENDPROC(sys_clone_wrapper) 470 471sys_sigreturn_wrapper: 472 add r0, sp, #S_OFF 473 mov why, #0 @ prevent syscall restart handling 474 b sys_sigreturn 475ENDPROC(sys_sigreturn_wrapper) 476 477sys_rt_sigreturn_wrapper: 478 add r0, sp, #S_OFF 479 mov why, #0 @ prevent syscall restart handling 480 b sys_rt_sigreturn 481ENDPROC(sys_rt_sigreturn_wrapper) 482 483sys_sigaltstack_wrapper: 484 ldr r2, [sp, #S_OFF + S_SP] 485 b do_sigaltstack 486ENDPROC(sys_sigaltstack_wrapper) 487 488sys_statfs64_wrapper: 489 teq r1, #88 490 moveq r1, #84 491 b sys_statfs64 492ENDPROC(sys_statfs64_wrapper) 493 494sys_fstatfs64_wrapper: 495 teq r1, #88 496 moveq r1, #84 497 b sys_fstatfs64 498ENDPROC(sys_fstatfs64_wrapper) 499 500/* 501 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 502 * offset, we return EINVAL. 503 */ 504sys_mmap2: 505#if PAGE_SHIFT > 12 506 tst r5, #PGOFF_MASK 507 moveq r5, r5, lsr #PAGE_SHIFT - 12 508 streq r5, [sp, #4] 509 beq sys_mmap_pgoff 510 mov r0, #-EINVAL 511 mov pc, lr 512#else 513 str r5, [sp, #4] 514 b sys_mmap_pgoff 515#endif 516ENDPROC(sys_mmap2) 517 518#ifdef CONFIG_OABI_COMPAT 519 520/* 521 * These are syscalls with argument register differences 522 */ 523 524sys_oabi_pread64: 525 stmia sp, {r3, r4} 526 b sys_pread64 527ENDPROC(sys_oabi_pread64) 528 529sys_oabi_pwrite64: 530 stmia sp, {r3, r4} 531 b sys_pwrite64 532ENDPROC(sys_oabi_pwrite64) 533 534sys_oabi_truncate64: 535 mov r3, r2 536 mov r2, r1 537 b sys_truncate64 538ENDPROC(sys_oabi_truncate64) 539 540sys_oabi_ftruncate64: 541 mov r3, r2 542 mov r2, r1 543 b sys_ftruncate64 544ENDPROC(sys_oabi_ftruncate64) 545 546sys_oabi_readahead: 547 str r3, [sp] 548 mov r3, r2 549 mov r2, r1 550 b sys_readahead 551ENDPROC(sys_oabi_readahead) 552 553/* 554 * Let's declare a second syscall table for old ABI binaries 555 * using the compatibility syscall entries. 556 */ 557#define ABI(native, compat) compat 558#define OBSOLETE(syscall) syscall 559 560 .type sys_oabi_call_table, #object 561ENTRY(sys_oabi_call_table) 562#include "calls.S" 563#undef ABI 564#undef OBSOLETE 565 566#endif 567 568