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/assembler.h> 12#include <asm/unistd.h> 13#include <asm/ftrace.h> 14#include <asm/unwind.h> 15#ifdef CONFIG_AEABI 16#include <asm/unistd-oabi.h> 17#endif 18 19 .equ NR_syscalls, __NR_syscalls 20 21#ifdef CONFIG_NEED_RET_TO_USER 22#include <mach/entry-macro.S> 23#else 24 .macro arch_ret_to_user, tmp1, tmp2 25 .endm 26#endif 27 28#include "entry-header.S" 29 30saved_psr .req r8 31#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING) 32saved_pc .req r9 33#define TRACE(x...) x 34#else 35saved_pc .req lr 36#define TRACE(x...) 37#endif 38 39 .align 5 40#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING)) 41/* 42 * This is the fast syscall return path. We do as little as possible here, 43 * such as avoiding writing r0 to the stack. We only use this path if we 44 * have tracing and context tracking disabled - the overheads from those 45 * features make this path too inefficient. 46 */ 47ret_fast_syscall: 48 UNWIND(.fnstart ) 49 UNWIND(.cantunwind ) 50 disable_irq_notrace @ disable interrupts 51 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 52 tst r1, #_TIF_SYSCALL_WORK 53 bne fast_work_pending 54 tst r1, #_TIF_WORK_MASK 55 bne fast_work_pending 56 57 /* perform architecture specific actions before user return */ 58 arch_ret_to_user r1, lr 59 60 restore_user_regs fast = 1, offset = S_OFF 61 UNWIND(.fnend ) 62ENDPROC(ret_fast_syscall) 63 64 /* Ok, we need to do extra processing, enter the slow path. */ 65fast_work_pending: 66 str r0, [sp, #S_R0+S_OFF]! @ returned r0 67 /* fall through to work_pending */ 68#else 69/* 70 * The "replacement" ret_fast_syscall for when tracing or context tracking 71 * is enabled. As we will need to call out to some C functions, we save 72 * r0 first to avoid needing to save registers around each C function call. 73 */ 74ret_fast_syscall: 75 UNWIND(.fnstart ) 76 UNWIND(.cantunwind ) 77 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 78 disable_irq_notrace @ disable interrupts 79 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 80 tst r1, #_TIF_SYSCALL_WORK 81 bne fast_work_pending 82 tst r1, #_TIF_WORK_MASK 83 beq no_work_pending 84 UNWIND(.fnend ) 85ENDPROC(ret_fast_syscall) 86 87 /* Slower path - fall through to work_pending */ 88fast_work_pending: 89#endif 90 91 tst r1, #_TIF_SYSCALL_WORK 92 bne __sys_trace_return_nosave 93slow_work_pending: 94 mov r0, sp @ 'regs' 95 mov r2, why @ 'syscall' 96 bl do_work_pending 97 cmp r0, #0 98 beq no_work_pending 99 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) 100 ldmia sp, {r0 - r6} @ have to reload r0 - r6 101 b local_restart @ ... and off we go 102ENDPROC(ret_fast_syscall) 103 104/* 105 * "slow" syscall return path. "why" tells us if this was a real syscall. 106 * IRQs may be enabled here, so always disable them. Note that we use the 107 * "notrace" version to avoid calling into the tracing code unnecessarily. 108 * do_work_pending() will update this state if necessary. 109 */ 110ENTRY(ret_to_user) 111ret_slow_syscall: 112 disable_irq_notrace @ disable interrupts 113ENTRY(ret_to_user_from_irq) 114 ldr r1, [tsk, #TI_FLAGS] 115 tst r1, #_TIF_WORK_MASK 116 bne slow_work_pending 117no_work_pending: 118 asm_trace_hardirqs_on save = 0 119 120 /* perform architecture specific actions before user return */ 121 arch_ret_to_user r1, lr 122 ct_user_enter save = 0 123 124 restore_user_regs fast = 0, offset = 0 125ENDPROC(ret_to_user_from_irq) 126ENDPROC(ret_to_user) 127 128/* 129 * This is how we return from a fork. 130 */ 131ENTRY(ret_from_fork) 132 bl schedule_tail 133 cmp r5, #0 134 movne r0, r4 135 badrne lr, 1f 136 retne r5 1371: get_thread_info tsk 138 b ret_slow_syscall 139ENDPROC(ret_from_fork) 140 141/*============================================================================= 142 * SWI handler 143 *----------------------------------------------------------------------------- 144 */ 145 146 .align 5 147ENTRY(vector_swi) 148#ifdef CONFIG_CPU_V7M 149 v7m_exception_entry 150#else 151 sub sp, sp, #PT_REGS_SIZE 152 stmia sp, {r0 - r12} @ Calling r0 - r12 153 ARM( add r8, sp, #S_PC ) 154 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 155 THUMB( mov r8, sp ) 156 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 157 mrs saved_psr, spsr @ called from non-FIQ mode, so ok. 158 TRACE( mov saved_pc, lr ) 159 str saved_pc, [sp, #S_PC] @ Save calling PC 160 str saved_psr, [sp, #S_PSR] @ Save CPSR 161 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 162#endif 163 zero_fp 164 alignment_trap r10, ip, __cr_alignment 165 asm_trace_hardirqs_on save=0 166 enable_irq_notrace 167 ct_user_exit save=0 168 169 /* 170 * Get the system call number. 171 */ 172 173#if defined(CONFIG_OABI_COMPAT) 174 175 /* 176 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 177 * value to determine if it is an EABI or an old ABI call. 178 */ 179#ifdef CONFIG_ARM_THUMB 180 tst saved_psr, #PSR_T_BIT 181 movne r10, #0 @ no thumb OABI emulation 182 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction 183#else 184 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction 185#endif 186 ARM_BE8(rev r10, r10) @ little endian instruction 187 188#elif defined(CONFIG_AEABI) 189 190 /* 191 * Pure EABI user space always put syscall number into scno (r7). 192 */ 193#elif defined(CONFIG_ARM_THUMB) 194 /* Legacy ABI only, possibly thumb mode. */ 195 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs 196 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 197 USER( ldreq scno, [saved_pc, #-4] ) 198 199#else 200 /* Legacy ABI only. */ 201 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction 202#endif 203 204 /* saved_psr and saved_pc are now dead */ 205 206 uaccess_disable tbl 207 208 adr tbl, sys_call_table @ load syscall table pointer 209 210#if defined(CONFIG_OABI_COMPAT) 211 /* 212 * If the swi argument is zero, this is an EABI call and we do nothing. 213 * 214 * If this is an old ABI call, get the syscall number into scno and 215 * get the old ABI syscall table address. 216 */ 217 bics r10, r10, #0xff000000 218 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 219 ldrne tbl, =sys_oabi_call_table 220#elif !defined(CONFIG_AEABI) 221 bic scno, scno, #0xff000000 @ mask off SWI op-code 222 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 223#endif 224 get_thread_info tsk 225 /* 226 * Reload the registers that may have been corrupted on entry to 227 * the syscall assembly (by tracing or context tracking.) 228 */ 229 TRACE( ldmia sp, {r0 - r3} ) 230 231local_restart: 232 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 233 stmdb sp!, {r4, r5} @ push fifth and sixth args 234 235 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 236 bne __sys_trace 237 238 cmp scno, #NR_syscalls @ check upper syscall limit 239 badr lr, ret_fast_syscall @ return address 240 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 241 242 add r1, sp, #S_OFF 2432: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 244 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 245 bcs arm_syscall 246 mov why, #0 @ no longer a real syscall 247 b sys_ni_syscall @ not private func 248 249#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 250 /* 251 * We failed to handle a fault trying to access the page 252 * containing the swi instruction, but we're not really in a 253 * position to return -EFAULT. Instead, return back to the 254 * instruction and re-enter the user fault handling path trying 255 * to page it in. This will likely result in sending SEGV to the 256 * current task. 257 */ 2589001: 259 sub lr, saved_pc, #4 260 str lr, [sp, #S_PC] 261 get_thread_info tsk 262 b ret_fast_syscall 263#endif 264ENDPROC(vector_swi) 265 266 /* 267 * This is the really slow path. We're going to be doing 268 * context switches, and waiting for our parent to respond. 269 */ 270__sys_trace: 271 mov r1, scno 272 add r0, sp, #S_OFF 273 bl syscall_trace_enter 274 275 badr lr, __sys_trace_return @ return address 276 mov scno, r0 @ syscall number (possibly new) 277 add r1, sp, #S_R0 + S_OFF @ pointer to regs 278 cmp scno, #NR_syscalls @ check upper syscall limit 279 ldmccia r1, {r0 - r6} @ have to reload r0 - r6 280 stmccia sp, {r4, r5} @ and update the stack args 281 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 282 cmp scno, #-1 @ skip the syscall? 283 bne 2b 284 add sp, sp, #S_OFF @ restore stack 285 b ret_slow_syscall 286 287__sys_trace_return: 288 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 289 mov r0, sp 290 bl syscall_trace_exit 291 b ret_slow_syscall 292 293__sys_trace_return_nosave: 294 enable_irq_notrace 295 mov r0, sp 296 bl syscall_trace_exit 297 b ret_slow_syscall 298 299 .align 5 300#ifdef CONFIG_ALIGNMENT_TRAP 301 .type __cr_alignment, #object 302__cr_alignment: 303 .word cr_alignment 304#endif 305 .ltorg 306 307 .macro syscall_table_start, sym 308 .equ __sys_nr, 0 309 .type \sym, #object 310ENTRY(\sym) 311 .endm 312 313 .macro syscall, nr, func 314 .ifgt __sys_nr - \nr 315 .error "Duplicated/unorded system call entry" 316 .endif 317 .rept \nr - __sys_nr 318 .long sys_ni_syscall 319 .endr 320 .long \func 321 .equ __sys_nr, \nr + 1 322 .endm 323 324 .macro syscall_table_end, sym 325 .ifgt __sys_nr - __NR_syscalls 326 .error "System call table too big" 327 .endif 328 .rept __NR_syscalls - __sys_nr 329 .long sys_ni_syscall 330 .endr 331 .size \sym, . - \sym 332 .endm 333 334#define NATIVE(nr, func) syscall nr, func 335 336/* 337 * This is the syscall table declaration for native ABI syscalls. 338 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 339 */ 340 syscall_table_start sys_call_table 341#define COMPAT(nr, native, compat) syscall nr, native 342#ifdef CONFIG_AEABI 343#include <calls-eabi.S> 344#else 345#include <calls-oabi.S> 346#endif 347#undef COMPAT 348 syscall_table_end sys_call_table 349 350/*============================================================================ 351 * Special system call wrappers 352 */ 353@ r0 = syscall number 354@ r8 = syscall table 355sys_syscall: 356 bic scno, r0, #__NR_OABI_SYSCALL_BASE 357 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 358 cmpne scno, #NR_syscalls @ check range 359 stmloia sp, {r5, r6} @ shuffle args 360 movlo r0, r1 361 movlo r1, r2 362 movlo r2, r3 363 movlo r3, r4 364 ldrlo pc, [tbl, scno, lsl #2] 365 b sys_ni_syscall 366ENDPROC(sys_syscall) 367 368sys_sigreturn_wrapper: 369 add r0, sp, #S_OFF 370 mov why, #0 @ prevent syscall restart handling 371 b sys_sigreturn 372ENDPROC(sys_sigreturn_wrapper) 373 374sys_rt_sigreturn_wrapper: 375 add r0, sp, #S_OFF 376 mov why, #0 @ prevent syscall restart handling 377 b sys_rt_sigreturn 378ENDPROC(sys_rt_sigreturn_wrapper) 379 380sys_statfs64_wrapper: 381 teq r1, #88 382 moveq r1, #84 383 b sys_statfs64 384ENDPROC(sys_statfs64_wrapper) 385 386sys_fstatfs64_wrapper: 387 teq r1, #88 388 moveq r1, #84 389 b sys_fstatfs64 390ENDPROC(sys_fstatfs64_wrapper) 391 392/* 393 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 394 * offset, we return EINVAL. 395 */ 396sys_mmap2: 397#if PAGE_SHIFT > 12 398 tst r5, #PGOFF_MASK 399 moveq r5, r5, lsr #PAGE_SHIFT - 12 400 streq r5, [sp, #4] 401 beq sys_mmap_pgoff 402 mov r0, #-EINVAL 403 ret lr 404#else 405 str r5, [sp, #4] 406 b sys_mmap_pgoff 407#endif 408ENDPROC(sys_mmap2) 409 410#ifdef CONFIG_OABI_COMPAT 411 412/* 413 * These are syscalls with argument register differences 414 */ 415 416sys_oabi_pread64: 417 stmia sp, {r3, r4} 418 b sys_pread64 419ENDPROC(sys_oabi_pread64) 420 421sys_oabi_pwrite64: 422 stmia sp, {r3, r4} 423 b sys_pwrite64 424ENDPROC(sys_oabi_pwrite64) 425 426sys_oabi_truncate64: 427 mov r3, r2 428 mov r2, r1 429 b sys_truncate64 430ENDPROC(sys_oabi_truncate64) 431 432sys_oabi_ftruncate64: 433 mov r3, r2 434 mov r2, r1 435 b sys_ftruncate64 436ENDPROC(sys_oabi_ftruncate64) 437 438sys_oabi_readahead: 439 str r3, [sp] 440 mov r3, r2 441 mov r2, r1 442 b sys_readahead 443ENDPROC(sys_oabi_readahead) 444 445/* 446 * Let's declare a second syscall table for old ABI binaries 447 * using the compatibility syscall entries. 448 */ 449 syscall_table_start sys_oabi_call_table 450#define COMPAT(nr, native, compat) syscall nr, compat 451#include <calls-oabi.S> 452 syscall_table_end sys_oabi_call_table 453 454#endif 455 456