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#ifdef CONFIG_DYNAMIC_FTRACE 134ENTRY(mcount) 135 stmdb sp!, {r0-r3, lr} 136 mov r0, lr 137 sub r0, r0, #MCOUNT_INSN_SIZE 138 139 .globl mcount_call 140mcount_call: 141 bl ftrace_stub 142 ldr lr, [fp, #-4] @ restore lr 143 ldmia sp!, {r0-r3, pc} 144 145ENTRY(ftrace_caller) 146 stmdb sp!, {r0-r3, lr} 147 ldr r1, [fp, #-4] 148 mov r0, lr 149 sub r0, r0, #MCOUNT_INSN_SIZE 150 151 .globl ftrace_call 152ftrace_call: 153 bl ftrace_stub 154 ldr lr, [fp, #-4] @ restore lr 155 ldmia sp!, {r0-r3, pc} 156 157#else 158 159ENTRY(__gnu_mcount_nc) 160 stmdb sp!, {r0-r3, lr} 161 ldr r0, =ftrace_trace_function 162 ldr r2, [r0] 163 adr r0, ftrace_stub 164 cmp r0, r2 165 bne gnu_trace 166 ldmia sp!, {r0-r3, ip, lr} 167 mov pc, ip 168 169gnu_trace: 170 ldr r1, [sp, #20] @ lr of instrumented routine 171 mov r0, lr 172 sub r0, r0, #MCOUNT_INSN_SIZE 173 mov lr, pc 174 mov pc, r2 175 ldmia sp!, {r0-r3, ip, lr} 176 mov pc, ip 177 178ENTRY(mcount) 179 stmdb sp!, {r0-r3, lr} 180 ldr r0, =ftrace_trace_function 181 ldr r2, [r0] 182 adr r0, ftrace_stub 183 cmp r0, r2 184 bne trace 185 ldr lr, [fp, #-4] @ restore lr 186 ldmia sp!, {r0-r3, pc} 187 188trace: 189 ldr r1, [fp, #-4] @ lr of instrumented routine 190 mov r0, lr 191 sub r0, r0, #MCOUNT_INSN_SIZE 192 mov lr, pc 193 mov pc, r2 194 ldr lr, [fp, #-4] @ restore lr 195 ldmia sp!, {r0-r3, pc} 196 197#endif /* CONFIG_DYNAMIC_FTRACE */ 198 199 .globl ftrace_stub 200ftrace_stub: 201 mov pc, lr 202 203#endif /* CONFIG_FUNCTION_TRACER */ 204 205/*============================================================================= 206 * SWI handler 207 *----------------------------------------------------------------------------- 208 */ 209 210 /* If we're optimising for StrongARM the resulting code won't 211 run on an ARM7 and we can save a couple of instructions. 212 --pb */ 213#ifdef CONFIG_CPU_ARM710 214#define A710(code...) code 215.Larm710bug: 216 ldmia sp, {r0 - lr}^ @ Get calling r0 - lr 217 mov r0, r0 218 add sp, sp, #S_FRAME_SIZE 219 subs pc, lr, #4 220#else 221#define A710(code...) 222#endif 223 224 .align 5 225ENTRY(vector_swi) 226 sub sp, sp, #S_FRAME_SIZE 227 stmia sp, {r0 - r12} @ Calling r0 - r12 228 ARM( add r8, sp, #S_PC ) 229 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 230 THUMB( mov r8, sp ) 231 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 232 mrs r8, spsr @ called from non-FIQ mode, so ok. 233 str lr, [sp, #S_PC] @ Save calling PC 234 str r8, [sp, #S_PSR] @ Save CPSR 235 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 236 zero_fp 237 238 /* 239 * Get the system call number. 240 */ 241 242#if defined(CONFIG_OABI_COMPAT) 243 244 /* 245 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 246 * value to determine if it is an EABI or an old ABI call. 247 */ 248#ifdef CONFIG_ARM_THUMB 249 tst r8, #PSR_T_BIT 250 movne r10, #0 @ no thumb OABI emulation 251 ldreq r10, [lr, #-4] @ get SWI instruction 252#else 253 ldr r10, [lr, #-4] @ get SWI instruction 254 A710( and ip, r10, #0x0f000000 @ check for SWI ) 255 A710( teq ip, #0x0f000000 ) 256 A710( bne .Larm710bug ) 257#endif 258#ifdef CONFIG_CPU_ENDIAN_BE8 259 rev r10, r10 @ little endian instruction 260#endif 261 262#elif defined(CONFIG_AEABI) 263 264 /* 265 * Pure EABI user space always put syscall number into scno (r7). 266 */ 267 A710( ldr ip, [lr, #-4] @ get SWI instruction ) 268 A710( and ip, ip, #0x0f000000 @ check for SWI ) 269 A710( teq ip, #0x0f000000 ) 270 A710( bne .Larm710bug ) 271 272#elif defined(CONFIG_ARM_THUMB) 273 274 /* Legacy ABI only, possibly thumb mode. */ 275 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs 276 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 277 ldreq scno, [lr, #-4] 278 279#else 280 281 /* Legacy ABI only. */ 282 ldr scno, [lr, #-4] @ get SWI instruction 283 A710( and ip, scno, #0x0f000000 @ check for SWI ) 284 A710( teq ip, #0x0f000000 ) 285 A710( bne .Larm710bug ) 286 287#endif 288 289#ifdef CONFIG_ALIGNMENT_TRAP 290 ldr ip, __cr_alignment 291 ldr ip, [ip] 292 mcr p15, 0, ip, c1, c0 @ update control register 293#endif 294 enable_irq 295 296 get_thread_info tsk 297 adr tbl, sys_call_table @ load syscall table pointer 298 ldr ip, [tsk, #TI_FLAGS] @ check for syscall tracing 299 300#if defined(CONFIG_OABI_COMPAT) 301 /* 302 * If the swi argument is zero, this is an EABI call and we do nothing. 303 * 304 * If this is an old ABI call, get the syscall number into scno and 305 * get the old ABI syscall table address. 306 */ 307 bics r10, r10, #0xff000000 308 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 309 ldrne tbl, =sys_oabi_call_table 310#elif !defined(CONFIG_AEABI) 311 bic scno, scno, #0xff000000 @ mask off SWI op-code 312 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 313#endif 314 315 stmdb sp!, {r4, r5} @ push fifth and sixth args 316 tst ip, #_TIF_SYSCALL_TRACE @ are we tracing syscalls? 317 bne __sys_trace 318 319 cmp scno, #NR_syscalls @ check upper syscall limit 320 adr lr, BSYM(ret_fast_syscall) @ return address 321 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 322 323 add r1, sp, #S_OFF 3242: mov why, #0 @ no longer a real syscall 325 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 326 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 327 bcs arm_syscall 328 b sys_ni_syscall @ not private func 329ENDPROC(vector_swi) 330 331 /* 332 * This is the really slow path. We're going to be doing 333 * context switches, and waiting for our parent to respond. 334 */ 335__sys_trace: 336 mov r2, scno 337 add r1, sp, #S_OFF 338 mov r0, #0 @ trace entry [IP = 0] 339 bl syscall_trace 340 341 adr lr, BSYM(__sys_trace_return) @ return address 342 mov scno, r0 @ syscall number (possibly new) 343 add r1, sp, #S_R0 + S_OFF @ pointer to regs 344 cmp scno, #NR_syscalls @ check upper syscall limit 345 ldmccia r1, {r0 - r3} @ have to reload r0 - r3 346 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 347 b 2b 348 349__sys_trace_return: 350 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 351 mov r2, scno 352 mov r1, sp 353 mov r0, #1 @ trace exit [IP = 1] 354 bl syscall_trace 355 b ret_slow_syscall 356 357 .align 5 358#ifdef CONFIG_ALIGNMENT_TRAP 359 .type __cr_alignment, #object 360__cr_alignment: 361 .word cr_alignment 362#endif 363 .ltorg 364 365/* 366 * This is the syscall table declaration for native ABI syscalls. 367 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 368 */ 369#define ABI(native, compat) native 370#ifdef CONFIG_AEABI 371#define OBSOLETE(syscall) sys_ni_syscall 372#else 373#define OBSOLETE(syscall) syscall 374#endif 375 376 .type sys_call_table, #object 377ENTRY(sys_call_table) 378#include "calls.S" 379#undef ABI 380#undef OBSOLETE 381 382/*============================================================================ 383 * Special system call wrappers 384 */ 385@ r0 = syscall number 386@ r8 = syscall table 387sys_syscall: 388 bic scno, r0, #__NR_OABI_SYSCALL_BASE 389 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 390 cmpne scno, #NR_syscalls @ check range 391 stmloia sp, {r5, r6} @ shuffle args 392 movlo r0, r1 393 movlo r1, r2 394 movlo r2, r3 395 movlo r3, r4 396 ldrlo pc, [tbl, scno, lsl #2] 397 b sys_ni_syscall 398ENDPROC(sys_syscall) 399 400sys_fork_wrapper: 401 add r0, sp, #S_OFF 402 b sys_fork 403ENDPROC(sys_fork_wrapper) 404 405sys_vfork_wrapper: 406 add r0, sp, #S_OFF 407 b sys_vfork 408ENDPROC(sys_vfork_wrapper) 409 410sys_execve_wrapper: 411 add r3, sp, #S_OFF 412 b sys_execve 413ENDPROC(sys_execve_wrapper) 414 415sys_clone_wrapper: 416 add ip, sp, #S_OFF 417 str ip, [sp, #4] 418 b sys_clone 419ENDPROC(sys_clone_wrapper) 420 421sys_sigreturn_wrapper: 422 add r0, sp, #S_OFF 423 mov why, #0 @ prevent syscall restart handling 424 b sys_sigreturn 425ENDPROC(sys_sigreturn_wrapper) 426 427sys_rt_sigreturn_wrapper: 428 add r0, sp, #S_OFF 429 mov why, #0 @ prevent syscall restart handling 430 b sys_rt_sigreturn 431ENDPROC(sys_rt_sigreturn_wrapper) 432 433sys_sigaltstack_wrapper: 434 ldr r2, [sp, #S_OFF + S_SP] 435 b do_sigaltstack 436ENDPROC(sys_sigaltstack_wrapper) 437 438sys_statfs64_wrapper: 439 teq r1, #88 440 moveq r1, #84 441 b sys_statfs64 442ENDPROC(sys_statfs64_wrapper) 443 444sys_fstatfs64_wrapper: 445 teq r1, #88 446 moveq r1, #84 447 b sys_fstatfs64 448ENDPROC(sys_fstatfs64_wrapper) 449 450/* 451 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 452 * offset, we return EINVAL. 453 */ 454sys_mmap2: 455#if PAGE_SHIFT > 12 456 tst r5, #PGOFF_MASK 457 moveq r5, r5, lsr #PAGE_SHIFT - 12 458 streq r5, [sp, #4] 459 beq sys_mmap_pgoff 460 mov r0, #-EINVAL 461 mov pc, lr 462#else 463 str r5, [sp, #4] 464 b sys_mmap_pgoff 465#endif 466ENDPROC(sys_mmap2) 467 468#ifdef CONFIG_OABI_COMPAT 469 470/* 471 * These are syscalls with argument register differences 472 */ 473 474sys_oabi_pread64: 475 stmia sp, {r3, r4} 476 b sys_pread64 477ENDPROC(sys_oabi_pread64) 478 479sys_oabi_pwrite64: 480 stmia sp, {r3, r4} 481 b sys_pwrite64 482ENDPROC(sys_oabi_pwrite64) 483 484sys_oabi_truncate64: 485 mov r3, r2 486 mov r2, r1 487 b sys_truncate64 488ENDPROC(sys_oabi_truncate64) 489 490sys_oabi_ftruncate64: 491 mov r3, r2 492 mov r2, r1 493 b sys_ftruncate64 494ENDPROC(sys_oabi_ftruncate64) 495 496sys_oabi_readahead: 497 str r3, [sp] 498 mov r3, r2 499 mov r2, r1 500 b sys_readahead 501ENDPROC(sys_oabi_readahead) 502 503/* 504 * Let's declare a second syscall table for old ABI binaries 505 * using the compatibility syscall entries. 506 */ 507#define ABI(native, compat) compat 508#define OBSOLETE(syscall) syscall 509 510 .type sys_oabi_call_table, #object 511ENTRY(sys_oabi_call_table) 512#include "calls.S" 513#undef ABI 514#undef OBSOLETE 515 516#endif 517