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#ifdef CONFIG_DYNAMIC_FTRACE 132ENTRY(mcount) 133 stmdb sp!, {r0-r3, lr} 134 mov r0, lr 135 sub r0, r0, #MCOUNT_INSN_SIZE 136 137 .globl mcount_call 138mcount_call: 139 bl ftrace_stub 140 ldr lr, [fp, #-4] @ restore lr 141 ldmia sp!, {r0-r3, pc} 142 143ENTRY(ftrace_caller) 144 stmdb sp!, {r0-r3, lr} 145 ldr r1, [fp, #-4] 146 mov r0, lr 147 sub r0, r0, #MCOUNT_INSN_SIZE 148 149 .globl ftrace_call 150ftrace_call: 151 bl ftrace_stub 152 ldr lr, [fp, #-4] @ restore lr 153 ldmia sp!, {r0-r3, pc} 154 155#else 156 157ENTRY(__gnu_mcount_nc) 158 stmdb sp!, {r0-r3, lr} 159 ldr r0, =ftrace_trace_function 160 ldr r2, [r0] 161 adr r0, ftrace_stub 162 cmp r0, r2 163 bne gnu_trace 164 ldmia sp!, {r0-r3, ip, lr} 165 mov pc, ip 166 167gnu_trace: 168 ldr r1, [sp, #20] @ lr of instrumented routine 169 mov r0, lr 170 sub r0, r0, #MCOUNT_INSN_SIZE 171 mov lr, pc 172 mov pc, r2 173 ldmia sp!, {r0-r3, ip, lr} 174 mov pc, ip 175 176ENTRY(mcount) 177 stmdb sp!, {r0-r3, lr} 178 ldr r0, =ftrace_trace_function 179 ldr r2, [r0] 180 adr r0, ftrace_stub 181 cmp r0, r2 182 bne trace 183 ldr lr, [fp, #-4] @ restore lr 184 ldmia sp!, {r0-r3, pc} 185 186trace: 187 ldr r1, [fp, #-4] @ lr of instrumented routine 188 mov r0, lr 189 sub r0, r0, #MCOUNT_INSN_SIZE 190 mov lr, pc 191 mov pc, r2 192 ldr lr, [fp, #-4] @ restore lr 193 ldmia sp!, {r0-r3, pc} 194 195#endif /* CONFIG_DYNAMIC_FTRACE */ 196 197 .globl ftrace_stub 198ftrace_stub: 199 mov pc, lr 200 201#endif /* CONFIG_FUNCTION_TRACER */ 202 203/*============================================================================= 204 * SWI handler 205 *----------------------------------------------------------------------------- 206 */ 207 208 /* If we're optimising for StrongARM the resulting code won't 209 run on an ARM7 and we can save a couple of instructions. 210 --pb */ 211#ifdef CONFIG_CPU_ARM710 212#define A710(code...) code 213.Larm710bug: 214 ldmia sp, {r0 - lr}^ @ Get calling r0 - lr 215 mov r0, r0 216 add sp, sp, #S_FRAME_SIZE 217 subs pc, lr, #4 218#else 219#define A710(code...) 220#endif 221 222 .align 5 223ENTRY(vector_swi) 224 sub sp, sp, #S_FRAME_SIZE 225 stmia sp, {r0 - r12} @ Calling r0 - r12 226 ARM( add r8, sp, #S_PC ) 227 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 228 THUMB( mov r8, sp ) 229 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 230 mrs r8, spsr @ called from non-FIQ mode, so ok. 231 str lr, [sp, #S_PC] @ Save calling PC 232 str r8, [sp, #S_PSR] @ Save CPSR 233 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 234 zero_fp 235 236 /* 237 * Get the system call number. 238 */ 239 240#if defined(CONFIG_OABI_COMPAT) 241 242 /* 243 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 244 * value to determine if it is an EABI or an old ABI call. 245 */ 246#ifdef CONFIG_ARM_THUMB 247 tst r8, #PSR_T_BIT 248 movne r10, #0 @ no thumb OABI emulation 249 ldreq r10, [lr, #-4] @ get SWI instruction 250#else 251 ldr r10, [lr, #-4] @ get SWI instruction 252 A710( and ip, r10, #0x0f000000 @ check for SWI ) 253 A710( teq ip, #0x0f000000 ) 254 A710( bne .Larm710bug ) 255#endif 256#ifdef CONFIG_CPU_ENDIAN_BE8 257 rev r10, r10 @ little endian instruction 258#endif 259 260#elif defined(CONFIG_AEABI) 261 262 /* 263 * Pure EABI user space always put syscall number into scno (r7). 264 */ 265 A710( ldr ip, [lr, #-4] @ get SWI instruction ) 266 A710( and ip, ip, #0x0f000000 @ check for SWI ) 267 A710( teq ip, #0x0f000000 ) 268 A710( bne .Larm710bug ) 269 270#elif defined(CONFIG_ARM_THUMB) 271 272 /* Legacy ABI only, possibly thumb mode. */ 273 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs 274 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 275 ldreq scno, [lr, #-4] 276 277#else 278 279 /* Legacy ABI only. */ 280 ldr scno, [lr, #-4] @ get SWI instruction 281 A710( and ip, scno, #0x0f000000 @ check for SWI ) 282 A710( teq ip, #0x0f000000 ) 283 A710( bne .Larm710bug ) 284 285#endif 286 287#ifdef CONFIG_ALIGNMENT_TRAP 288 ldr ip, __cr_alignment 289 ldr ip, [ip] 290 mcr p15, 0, ip, c1, c0 @ update control register 291#endif 292 enable_irq 293 294 get_thread_info tsk 295 adr tbl, sys_call_table @ load syscall table pointer 296 ldr ip, [tsk, #TI_FLAGS] @ check for syscall tracing 297 298#if defined(CONFIG_OABI_COMPAT) 299 /* 300 * If the swi argument is zero, this is an EABI call and we do nothing. 301 * 302 * If this is an old ABI call, get the syscall number into scno and 303 * get the old ABI syscall table address. 304 */ 305 bics r10, r10, #0xff000000 306 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 307 ldrne tbl, =sys_oabi_call_table 308#elif !defined(CONFIG_AEABI) 309 bic scno, scno, #0xff000000 @ mask off SWI op-code 310 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 311#endif 312 313 stmdb sp!, {r4, r5} @ push fifth and sixth args 314 tst ip, #_TIF_SYSCALL_TRACE @ are we tracing syscalls? 315 bne __sys_trace 316 317 cmp scno, #NR_syscalls @ check upper syscall limit 318 adr lr, BSYM(ret_fast_syscall) @ return address 319 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 320 321 add r1, sp, #S_OFF 3222: mov why, #0 @ no longer a real syscall 323 cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 324 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 325 bcs arm_syscall 326 b sys_ni_syscall @ not private func 327ENDPROC(vector_swi) 328 329 /* 330 * This is the really slow path. We're going to be doing 331 * context switches, and waiting for our parent to respond. 332 */ 333__sys_trace: 334 mov r2, scno 335 add r1, sp, #S_OFF 336 mov r0, #0 @ trace entry [IP = 0] 337 bl syscall_trace 338 339 adr lr, BSYM(__sys_trace_return) @ return address 340 mov scno, r0 @ syscall number (possibly new) 341 add r1, sp, #S_R0 + S_OFF @ pointer to regs 342 cmp scno, #NR_syscalls @ check upper syscall limit 343 ldmccia r1, {r0 - r3} @ have to reload r0 - r3 344 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 345 b 2b 346 347__sys_trace_return: 348 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 349 mov r2, scno 350 mov r1, sp 351 mov r0, #1 @ trace exit [IP = 1] 352 bl syscall_trace 353 b ret_slow_syscall 354 355 .align 5 356#ifdef CONFIG_ALIGNMENT_TRAP 357 .type __cr_alignment, #object 358__cr_alignment: 359 .word cr_alignment 360#endif 361 .ltorg 362 363/* 364 * This is the syscall table declaration for native ABI syscalls. 365 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 366 */ 367#define ABI(native, compat) native 368#ifdef CONFIG_AEABI 369#define OBSOLETE(syscall) sys_ni_syscall 370#else 371#define OBSOLETE(syscall) syscall 372#endif 373 374 .type sys_call_table, #object 375ENTRY(sys_call_table) 376#include "calls.S" 377#undef ABI 378#undef OBSOLETE 379 380/*============================================================================ 381 * Special system call wrappers 382 */ 383@ r0 = syscall number 384@ r8 = syscall table 385sys_syscall: 386 bic scno, r0, #__NR_OABI_SYSCALL_BASE 387 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 388 cmpne scno, #NR_syscalls @ check range 389 stmloia sp, {r5, r6} @ shuffle args 390 movlo r0, r1 391 movlo r1, r2 392 movlo r2, r3 393 movlo r3, r4 394 ldrlo pc, [tbl, scno, lsl #2] 395 b sys_ni_syscall 396ENDPROC(sys_syscall) 397 398sys_fork_wrapper: 399 add r0, sp, #S_OFF 400 b sys_fork 401ENDPROC(sys_fork_wrapper) 402 403sys_vfork_wrapper: 404 add r0, sp, #S_OFF 405 b sys_vfork 406ENDPROC(sys_vfork_wrapper) 407 408sys_execve_wrapper: 409 add r3, sp, #S_OFF 410 b sys_execve 411ENDPROC(sys_execve_wrapper) 412 413sys_clone_wrapper: 414 add ip, sp, #S_OFF 415 str ip, [sp, #4] 416 b sys_clone 417ENDPROC(sys_clone_wrapper) 418 419sys_sigreturn_wrapper: 420 add r0, sp, #S_OFF 421 b sys_sigreturn 422ENDPROC(sys_sigreturn_wrapper) 423 424sys_rt_sigreturn_wrapper: 425 add r0, sp, #S_OFF 426 b sys_rt_sigreturn 427ENDPROC(sys_rt_sigreturn_wrapper) 428 429sys_sigaltstack_wrapper: 430 ldr r2, [sp, #S_OFF + S_SP] 431 b do_sigaltstack 432ENDPROC(sys_sigaltstack_wrapper) 433 434sys_statfs64_wrapper: 435 teq r1, #88 436 moveq r1, #84 437 b sys_statfs64 438ENDPROC(sys_statfs64_wrapper) 439 440sys_fstatfs64_wrapper: 441 teq r1, #88 442 moveq r1, #84 443 b sys_fstatfs64 444ENDPROC(sys_fstatfs64_wrapper) 445 446/* 447 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 448 * offset, we return EINVAL. 449 */ 450sys_mmap2: 451#if PAGE_SHIFT > 12 452 tst r5, #PGOFF_MASK 453 moveq r5, r5, lsr #PAGE_SHIFT - 12 454 streq r5, [sp, #4] 455 beq sys_mmap_pgoff 456 mov r0, #-EINVAL 457 mov pc, lr 458#else 459 str r5, [sp, #4] 460 b sys_mmap_pgoff 461#endif 462ENDPROC(sys_mmap2) 463 464#ifdef CONFIG_OABI_COMPAT 465 466/* 467 * These are syscalls with argument register differences 468 */ 469 470sys_oabi_pread64: 471 stmia sp, {r3, r4} 472 b sys_pread64 473ENDPROC(sys_oabi_pread64) 474 475sys_oabi_pwrite64: 476 stmia sp, {r3, r4} 477 b sys_pwrite64 478ENDPROC(sys_oabi_pwrite64) 479 480sys_oabi_truncate64: 481 mov r3, r2 482 mov r2, r1 483 b sys_truncate64 484ENDPROC(sys_oabi_truncate64) 485 486sys_oabi_ftruncate64: 487 mov r3, r2 488 mov r2, r1 489 b sys_ftruncate64 490ENDPROC(sys_oabi_ftruncate64) 491 492sys_oabi_readahead: 493 str r3, [sp] 494 mov r3, r2 495 mov r2, r1 496 b sys_readahead 497ENDPROC(sys_oabi_readahead) 498 499/* 500 * Let's declare a second syscall table for old ABI binaries 501 * using the compatibility syscall entries. 502 */ 503#define ABI(native, compat) compat 504#define OBSOLETE(syscall) syscall 505 506 .type sys_oabi_call_table, #object 507ENTRY(sys_oabi_call_table) 508#include "calls.S" 509#undef ABI 510#undef OBSOLETE 511 512#endif 513 514