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 bl do_notify_resume 52 b ret_slow_syscall @ Check work again 53 54work_resched: 55 bl schedule 56/* 57 * "slow" syscall return path. "why" tells us if this was a real syscall. 58 */ 59ENTRY(ret_to_user) 60ret_slow_syscall: 61 disable_irq @ disable interrupts 62 ldr r1, [tsk, #TI_FLAGS] 63 tst r1, #_TIF_WORK_MASK 64 bne work_pending 65no_work_pending: 66 /* perform architecture specific actions before user return */ 67 arch_ret_to_user r1, lr 68 69 restore_user_regs fast = 0, offset = 0 70ENDPROC(ret_to_user) 71 72/* 73 * This is how we return from a fork. 74 */ 75ENTRY(ret_from_fork) 76 bl schedule_tail 77 get_thread_info tsk 78 ldr r1, [tsk, #TI_FLAGS] @ check for syscall tracing 79 mov why, #1 80 tst r1, #_TIF_SYSCALL_TRACE @ are we tracing syscalls? 81 beq ret_slow_syscall 82 mov r1, sp 83 mov r0, #1 @ trace exit [IP = 1] 84 bl syscall_trace 85 b ret_slow_syscall 86ENDPROC(ret_from_fork) 87 88 .equ NR_syscalls,0 89#define CALL(x) .equ NR_syscalls,NR_syscalls+1 90#include "calls.S" 91#undef CALL 92#define CALL(x) .long x 93 94#ifdef CONFIG_FUNCTION_TRACER 95/* 96 * When compiling with -pg, gcc inserts a call to the mcount routine at the 97 * start of every function. In mcount, apart from the function's address (in 98 * lr), we need to get hold of the function's caller's address. 99 * 100 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this: 101 * 102 * bl mcount 103 * 104 * These versions have the limitation that in order for the mcount routine to 105 * be able to determine the function's caller's address, an APCS-style frame 106 * pointer (which is set up with something like the code below) is required. 107 * 108 * mov ip, sp 109 * push {fp, ip, lr, pc} 110 * sub fp, ip, #4 111 * 112 * With EABI, these frame pointers are not available unless -mapcs-frame is 113 * specified, and if building as Thumb-2, not even then. 114 * 115 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount, 116 * with call sites like: 117 * 118 * push {lr} 119 * bl __gnu_mcount_nc 120 * 121 * With these compilers, frame pointers are not necessary. 122 * 123 * mcount can be thought of as a function called in the middle of a subroutine 124 * call. As such, it needs to be transparent for both the caller and the 125 * callee: the original lr needs to be restored when leaving mcount, and no 126 * registers should be clobbered. (In the __gnu_mcount_nc implementation, we 127 * clobber the ip register. This is OK because the ARM calling convention 128 * allows it to be clobbered in subroutines and doesn't use it to hold 129 * parameters.) 130 * 131 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0" 132 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see 133 * arch/arm/kernel/ftrace.c). 134 */ 135 136#ifndef CONFIG_OLD_MCOUNT 137#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4)) 138#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0. 139#endif 140#endif 141 142#ifdef CONFIG_DYNAMIC_FTRACE 143ENTRY(__gnu_mcount_nc) 144 mov ip, lr 145 ldmia sp!, {lr} 146 mov pc, ip 147ENDPROC(__gnu_mcount_nc) 148 149ENTRY(ftrace_caller) 150 stmdb sp!, {r0-r3, lr} 151 mov r0, lr 152 sub r0, r0, #MCOUNT_INSN_SIZE 153 ldr r1, [sp, #20] 154 155 .global ftrace_call 156ftrace_call: 157 bl ftrace_stub 158 ldmia sp!, {r0-r3, ip, lr} 159 mov pc, ip 160ENDPROC(ftrace_caller) 161 162#ifdef CONFIG_OLD_MCOUNT 163ENTRY(mcount) 164 stmdb sp!, {lr} 165 ldr lr, [fp, #-4] 166 ldmia sp!, {pc} 167ENDPROC(mcount) 168 169ENTRY(ftrace_caller_old) 170 stmdb sp!, {r0-r3, lr} 171 ldr r1, [fp, #-4] 172 mov r0, lr 173 sub r0, r0, #MCOUNT_INSN_SIZE 174 175 .globl ftrace_call_old 176ftrace_call_old: 177 bl ftrace_stub 178 ldr lr, [fp, #-4] @ restore lr 179 ldmia sp!, {r0-r3, pc} 180ENDPROC(ftrace_caller_old) 181#endif 182 183#else 184 185ENTRY(__gnu_mcount_nc) 186 stmdb sp!, {r0-r3, lr} 187 ldr r0, =ftrace_trace_function 188 ldr r2, [r0] 189 adr r0, .Lftrace_stub 190 cmp r0, r2 191 bne gnu_trace 192 ldmia sp!, {r0-r3, ip, lr} 193 mov pc, ip 194 195gnu_trace: 196 ldr r1, [sp, #20] @ lr of instrumented routine 197 mov r0, lr 198 sub r0, r0, #MCOUNT_INSN_SIZE 199 adr lr, BSYM(1f) 200 mov pc, r2 2011: 202 ldmia sp!, {r0-r3, ip, lr} 203 mov pc, ip 204ENDPROC(__gnu_mcount_nc) 205 206#ifdef CONFIG_OLD_MCOUNT 207/* 208 * This is under an ifdef in order to force link-time errors for people trying 209 * to build with !FRAME_POINTER with a GCC which doesn't use the new-style 210 * mcount. 211 */ 212ENTRY(mcount) 213 stmdb sp!, {r0-r3, lr} 214 ldr r0, =ftrace_trace_function 215 ldr r2, [r0] 216 adr r0, ftrace_stub 217 cmp r0, r2 218 bne trace 219 ldr lr, [fp, #-4] @ restore lr 220 ldmia sp!, {r0-r3, pc} 221 222trace: 223 ldr r1, [fp, #-4] @ lr of instrumented routine 224 mov r0, lr 225 sub r0, r0, #MCOUNT_INSN_SIZE 226 mov lr, pc 227 mov pc, r2 228 ldr lr, [fp, #-4] @ restore lr 229 ldmia sp!, {r0-r3, pc} 230ENDPROC(mcount) 231#endif 232 233#endif /* CONFIG_DYNAMIC_FTRACE */ 234 235ENTRY(ftrace_stub) 236.Lftrace_stub: 237 mov pc, lr 238ENDPROC(ftrace_stub) 239 240#endif /* CONFIG_FUNCTION_TRACER */ 241 242/*============================================================================= 243 * SWI handler 244 *----------------------------------------------------------------------------- 245 */ 246 247 /* If we're optimising for StrongARM the resulting code won't 248 run on an ARM7 and we can save a couple of instructions. 249 --pb */ 250#ifdef CONFIG_CPU_ARM710 251#define A710(code...) code 252.Larm710bug: 253 ldmia sp, {r0 - lr}^ @ Get calling r0 - lr 254 mov r0, r0 255 add sp, sp, #S_FRAME_SIZE 256 subs pc, lr, #4 257#else 258#define A710(code...) 259#endif 260 261 .align 5 262ENTRY(vector_swi) 263 sub sp, sp, #S_FRAME_SIZE 264 stmia sp, {r0 - r12} @ Calling r0 - r12 265 ARM( add r8, sp, #S_PC ) 266 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 267 THUMB( mov r8, sp ) 268 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 269 mrs r8, spsr @ called from non-FIQ mode, so ok. 270 str lr, [sp, #S_PC] @ Save calling PC 271 str r8, [sp, #S_PSR] @ Save CPSR 272 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 273 zero_fp 274 275 /* 276 * Get the system call number. 277 */ 278 279#if defined(CONFIG_OABI_COMPAT) 280 281 /* 282 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 283 * value to determine if it is an EABI or an old ABI call. 284 */ 285#ifdef CONFIG_ARM_THUMB 286 tst r8, #PSR_T_BIT 287 movne r10, #0 @ no thumb OABI emulation 288 ldreq r10, [lr, #-4] @ get SWI instruction 289#else 290 ldr r10, [lr, #-4] @ get SWI instruction 291 A710( and ip, r10, #0x0f000000 @ check for SWI ) 292 A710( teq ip, #0x0f000000 ) 293 A710( bne .Larm710bug ) 294#endif 295#ifdef CONFIG_CPU_ENDIAN_BE8 296 rev r10, r10 @ little endian instruction 297#endif 298 299#elif defined(CONFIG_AEABI) 300 301 /* 302 * Pure EABI user space always put syscall number into scno (r7). 303 */ 304 A710( ldr ip, [lr, #-4] @ get SWI instruction ) 305 A710( and ip, ip, #0x0f000000 @ check for SWI ) 306 A710( teq ip, #0x0f000000 ) 307 A710( bne .Larm710bug ) 308 309#elif defined(CONFIG_ARM_THUMB) 310 311 /* Legacy ABI only, possibly thumb mode. */ 312 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs 313 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 314 ldreq scno, [lr, #-4] 315 316#else 317 318 /* Legacy ABI only. */ 319 ldr scno, [lr, #-4] @ get SWI instruction 320 A710( and ip, scno, #0x0f000000 @ check for SWI ) 321 A710( teq ip, #0x0f000000 ) 322 A710( bne .Larm710bug ) 323 324#endif 325 326#ifdef CONFIG_ALIGNMENT_TRAP 327 ldr ip, __cr_alignment 328 ldr ip, [ip] 329 mcr p15, 0, ip, c1, c0 @ update control register 330#endif 331 enable_irq 332 333 get_thread_info tsk 334 adr tbl, sys_call_table @ load syscall table pointer 335 ldr ip, [tsk, #TI_FLAGS] @ check for syscall tracing 336 337#if defined(CONFIG_OABI_COMPAT) 338 /* 339 * If the swi argument is zero, this is an EABI call and we do nothing. 340 * 341 * If this is an old ABI call, get the syscall number into scno and 342 * get the old ABI syscall table address. 343 */ 344 bics r10, r10, #0xff000000 345 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 346 ldrne tbl, =sys_oabi_call_table 347#elif !defined(CONFIG_AEABI) 348 bic scno, scno, #0xff000000 @ mask off SWI op-code 349 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 350#endif 351 352 stmdb sp!, {r4, r5} @ push fifth and sixth args 353 tst ip, #_TIF_SYSCALL_TRACE @ are we tracing syscalls? 354 bne __sys_trace 355 356 cmp scno, #NR_syscalls @ check upper syscall limit 357 adr lr, BSYM(ret_fast_syscall) @ return address 358 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 359 360 add r1, sp, #S_OFF 3612: mov why, #0 @ no longer a real syscall 362 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 363 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 364 bcs arm_syscall 365 b sys_ni_syscall @ not private func 366ENDPROC(vector_swi) 367 368 /* 369 * This is the really slow path. We're going to be doing 370 * context switches, and waiting for our parent to respond. 371 */ 372__sys_trace: 373 mov r2, scno 374 add r1, sp, #S_OFF 375 mov r0, #0 @ trace entry [IP = 0] 376 bl syscall_trace 377 378 adr lr, BSYM(__sys_trace_return) @ return address 379 mov scno, r0 @ syscall number (possibly new) 380 add r1, sp, #S_R0 + S_OFF @ pointer to regs 381 cmp scno, #NR_syscalls @ check upper syscall limit 382 ldmccia r1, {r0 - r3} @ have to reload r0 - r3 383 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 384 b 2b 385 386__sys_trace_return: 387 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 388 mov r2, scno 389 mov r1, sp 390 mov r0, #1 @ trace exit [IP = 1] 391 bl syscall_trace 392 b ret_slow_syscall 393 394 .align 5 395#ifdef CONFIG_ALIGNMENT_TRAP 396 .type __cr_alignment, #object 397__cr_alignment: 398 .word cr_alignment 399#endif 400 .ltorg 401 402/* 403 * This is the syscall table declaration for native ABI syscalls. 404 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 405 */ 406#define ABI(native, compat) native 407#ifdef CONFIG_AEABI 408#define OBSOLETE(syscall) sys_ni_syscall 409#else 410#define OBSOLETE(syscall) syscall 411#endif 412 413 .type sys_call_table, #object 414ENTRY(sys_call_table) 415#include "calls.S" 416#undef ABI 417#undef OBSOLETE 418 419/*============================================================================ 420 * Special system call wrappers 421 */ 422@ r0 = syscall number 423@ r8 = syscall table 424sys_syscall: 425 bic scno, r0, #__NR_OABI_SYSCALL_BASE 426 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 427 cmpne scno, #NR_syscalls @ check range 428 stmloia sp, {r5, r6} @ shuffle args 429 movlo r0, r1 430 movlo r1, r2 431 movlo r2, r3 432 movlo r3, r4 433 ldrlo pc, [tbl, scno, lsl #2] 434 b sys_ni_syscall 435ENDPROC(sys_syscall) 436 437sys_fork_wrapper: 438 add r0, sp, #S_OFF 439 b sys_fork 440ENDPROC(sys_fork_wrapper) 441 442sys_vfork_wrapper: 443 add r0, sp, #S_OFF 444 b sys_vfork 445ENDPROC(sys_vfork_wrapper) 446 447sys_execve_wrapper: 448 add r3, sp, #S_OFF 449 b sys_execve 450ENDPROC(sys_execve_wrapper) 451 452sys_clone_wrapper: 453 add ip, sp, #S_OFF 454 str ip, [sp, #4] 455 b sys_clone 456ENDPROC(sys_clone_wrapper) 457 458sys_sigreturn_wrapper: 459 add r0, sp, #S_OFF 460 b sys_sigreturn 461ENDPROC(sys_sigreturn_wrapper) 462 463sys_rt_sigreturn_wrapper: 464 add r0, sp, #S_OFF 465 b sys_rt_sigreturn 466ENDPROC(sys_rt_sigreturn_wrapper) 467 468sys_sigaltstack_wrapper: 469 ldr r2, [sp, #S_OFF + S_SP] 470 b do_sigaltstack 471ENDPROC(sys_sigaltstack_wrapper) 472 473sys_statfs64_wrapper: 474 teq r1, #88 475 moveq r1, #84 476 b sys_statfs64 477ENDPROC(sys_statfs64_wrapper) 478 479sys_fstatfs64_wrapper: 480 teq r1, #88 481 moveq r1, #84 482 b sys_fstatfs64 483ENDPROC(sys_fstatfs64_wrapper) 484 485/* 486 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 487 * offset, we return EINVAL. 488 */ 489sys_mmap2: 490#if PAGE_SHIFT > 12 491 tst r5, #PGOFF_MASK 492 moveq r5, r5, lsr #PAGE_SHIFT - 12 493 streq r5, [sp, #4] 494 beq sys_mmap_pgoff 495 mov r0, #-EINVAL 496 mov pc, lr 497#else 498 str r5, [sp, #4] 499 b sys_mmap_pgoff 500#endif 501ENDPROC(sys_mmap2) 502 503#ifdef CONFIG_OABI_COMPAT 504 505/* 506 * These are syscalls with argument register differences 507 */ 508 509sys_oabi_pread64: 510 stmia sp, {r3, r4} 511 b sys_pread64 512ENDPROC(sys_oabi_pread64) 513 514sys_oabi_pwrite64: 515 stmia sp, {r3, r4} 516 b sys_pwrite64 517ENDPROC(sys_oabi_pwrite64) 518 519sys_oabi_truncate64: 520 mov r3, r2 521 mov r2, r1 522 b sys_truncate64 523ENDPROC(sys_oabi_truncate64) 524 525sys_oabi_ftruncate64: 526 mov r3, r2 527 mov r2, r1 528 b sys_ftruncate64 529ENDPROC(sys_oabi_ftruncate64) 530 531sys_oabi_readahead: 532 str r3, [sp] 533 mov r3, r2 534 mov r2, r1 535 b sys_readahead 536ENDPROC(sys_oabi_readahead) 537 538/* 539 * Let's declare a second syscall table for old ABI binaries 540 * using the compatibility syscall entries. 541 */ 542#define ABI(native, compat) compat 543#define OBSOLETE(syscall) syscall 544 545 .type sys_oabi_call_table, #object 546ENTRY(sys_oabi_call_table) 547#include "calls.S" 548#undef ABI 549#undef OBSOLETE 550 551#endif 552 553