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#include <asm/memory.h> 16#ifdef CONFIG_AEABI 17#include <asm/unistd-oabi.h> 18#endif 19 20 .equ NR_syscalls, __NR_syscalls 21 22#ifdef CONFIG_NEED_RET_TO_USER 23#include <mach/entry-macro.S> 24#else 25 .macro arch_ret_to_user, tmp1, tmp2 26 .endm 27#endif 28 29#include "entry-header.S" 30 31saved_psr .req r8 32#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING) 33saved_pc .req r9 34#define TRACE(x...) x 35#else 36saved_pc .req lr 37#define TRACE(x...) 38#endif 39 40 .align 5 41#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING)) 42/* 43 * This is the fast syscall return path. We do as little as possible here, 44 * such as avoiding writing r0 to the stack. We only use this path if we 45 * have tracing and context tracking disabled - the overheads from those 46 * features make this path too inefficient. 47 */ 48ret_fast_syscall: 49 UNWIND(.fnstart ) 50 UNWIND(.cantunwind ) 51 disable_irq_notrace @ disable interrupts 52 ldr r2, [tsk, #TI_ADDR_LIMIT] 53 cmp r2, #TASK_SIZE 54 blne addr_limit_check_failed 55 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 56 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK 57 bne fast_work_pending 58 59 60 /* perform architecture specific actions before user return */ 61 arch_ret_to_user r1, lr 62 63 restore_user_regs fast = 1, offset = S_OFF 64 UNWIND(.fnend ) 65ENDPROC(ret_fast_syscall) 66 67 /* Ok, we need to do extra processing, enter the slow path. */ 68fast_work_pending: 69 str r0, [sp, #S_R0+S_OFF]! @ returned r0 70 /* fall through to work_pending */ 71#else 72/* 73 * The "replacement" ret_fast_syscall for when tracing or context tracking 74 * is enabled. As we will need to call out to some C functions, we save 75 * r0 first to avoid needing to save registers around each C function call. 76 */ 77ret_fast_syscall: 78 UNWIND(.fnstart ) 79 UNWIND(.cantunwind ) 80 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 81 disable_irq_notrace @ disable interrupts 82 ldr r2, [tsk, #TI_ADDR_LIMIT] 83 cmp r2, #TASK_SIZE 84 blne addr_limit_check_failed 85 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 86 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK 87 beq no_work_pending 88 UNWIND(.fnend ) 89ENDPROC(ret_fast_syscall) 90 91 /* Slower path - fall through to work_pending */ 92#endif 93 94 tst r1, #_TIF_SYSCALL_WORK 95 bne __sys_trace_return_nosave 96slow_work_pending: 97 mov r0, sp @ 'regs' 98 mov r2, why @ 'syscall' 99 bl do_work_pending 100 cmp r0, #0 101 beq no_work_pending 102 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) 103 ldmia sp, {r0 - r6} @ have to reload r0 - r6 104 b local_restart @ ... and off we go 105ENDPROC(ret_fast_syscall) 106 107/* 108 * "slow" syscall return path. "why" tells us if this was a real syscall. 109 * IRQs may be enabled here, so always disable them. Note that we use the 110 * "notrace" version to avoid calling into the tracing code unnecessarily. 111 * do_work_pending() will update this state if necessary. 112 */ 113ENTRY(ret_to_user) 114ret_slow_syscall: 115 disable_irq_notrace @ disable interrupts 116ENTRY(ret_to_user_from_irq) 117 ldr r2, [tsk, #TI_ADDR_LIMIT] 118 cmp r2, #TASK_SIZE 119 blne addr_limit_check_failed 120 ldr r1, [tsk, #TI_FLAGS] 121 tst r1, #_TIF_WORK_MASK 122 bne slow_work_pending 123no_work_pending: 124 asm_trace_hardirqs_on save = 0 125 126 /* perform architecture specific actions before user return */ 127 arch_ret_to_user r1, lr 128 ct_user_enter save = 0 129 130 restore_user_regs fast = 0, offset = 0 131ENDPROC(ret_to_user_from_irq) 132ENDPROC(ret_to_user) 133 134/* 135 * This is how we return from a fork. 136 */ 137ENTRY(ret_from_fork) 138 bl schedule_tail 139 cmp r5, #0 140 movne r0, r4 141 badrne lr, 1f 142 retne r5 1431: get_thread_info tsk 144 b ret_slow_syscall 145ENDPROC(ret_from_fork) 146 147/*============================================================================= 148 * SWI handler 149 *----------------------------------------------------------------------------- 150 */ 151 152 .align 5 153ENTRY(vector_swi) 154#ifdef CONFIG_CPU_V7M 155 v7m_exception_entry 156#else 157 sub sp, sp, #PT_REGS_SIZE 158 stmia sp, {r0 - r12} @ Calling r0 - r12 159 ARM( add r8, sp, #S_PC ) 160 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 161 THUMB( mov r8, sp ) 162 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 163 mrs saved_psr, spsr @ called from non-FIQ mode, so ok. 164 TRACE( mov saved_pc, lr ) 165 str saved_pc, [sp, #S_PC] @ Save calling PC 166 str saved_psr, [sp, #S_PSR] @ Save CPSR 167 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 168#endif 169 zero_fp 170 alignment_trap r10, ip, __cr_alignment 171 asm_trace_hardirqs_on save=0 172 enable_irq_notrace 173 ct_user_exit save=0 174 175 /* 176 * Get the system call number. 177 */ 178 179#if defined(CONFIG_OABI_COMPAT) 180 181 /* 182 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 183 * value to determine if it is an EABI or an old ABI call. 184 */ 185#ifdef CONFIG_ARM_THUMB 186 tst saved_psr, #PSR_T_BIT 187 movne r10, #0 @ no thumb OABI emulation 188 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction 189#else 190 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction 191#endif 192 ARM_BE8(rev r10, r10) @ little endian instruction 193 194#elif defined(CONFIG_AEABI) 195 196 /* 197 * Pure EABI user space always put syscall number into scno (r7). 198 */ 199#elif defined(CONFIG_ARM_THUMB) 200 /* Legacy ABI only, possibly thumb mode. */ 201 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs 202 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 203 USER( ldreq scno, [saved_pc, #-4] ) 204 205#else 206 /* Legacy ABI only. */ 207 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction 208#endif 209 210 /* saved_psr and saved_pc are now dead */ 211 212 uaccess_disable tbl 213 214 adr tbl, sys_call_table @ load syscall table pointer 215 216#if defined(CONFIG_OABI_COMPAT) 217 /* 218 * If the swi argument is zero, this is an EABI call and we do nothing. 219 * 220 * If this is an old ABI call, get the syscall number into scno and 221 * get the old ABI syscall table address. 222 */ 223 bics r10, r10, #0xff000000 224 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 225 ldrne tbl, =sys_oabi_call_table 226#elif !defined(CONFIG_AEABI) 227 bic scno, scno, #0xff000000 @ mask off SWI op-code 228 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 229#endif 230 get_thread_info tsk 231 /* 232 * Reload the registers that may have been corrupted on entry to 233 * the syscall assembly (by tracing or context tracking.) 234 */ 235 TRACE( ldmia sp, {r0 - r3} ) 236 237local_restart: 238 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 239 stmdb sp!, {r4, r5} @ push fifth and sixth args 240 241 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 242 bne __sys_trace 243 244 cmp scno, #NR_syscalls @ check upper syscall limit 245 badr lr, ret_fast_syscall @ return address 246 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 247 248 add r1, sp, #S_OFF 2492: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 250 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 251 bcs arm_syscall 252 mov why, #0 @ no longer a real syscall 253 b sys_ni_syscall @ not private func 254 255#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 256 /* 257 * We failed to handle a fault trying to access the page 258 * containing the swi instruction, but we're not really in a 259 * position to return -EFAULT. Instead, return back to the 260 * instruction and re-enter the user fault handling path trying 261 * to page it in. This will likely result in sending SEGV to the 262 * current task. 263 */ 2649001: 265 sub lr, saved_pc, #4 266 str lr, [sp, #S_PC] 267 get_thread_info tsk 268 b ret_fast_syscall 269#endif 270ENDPROC(vector_swi) 271 272 /* 273 * This is the really slow path. We're going to be doing 274 * context switches, and waiting for our parent to respond. 275 */ 276__sys_trace: 277 mov r1, scno 278 add r0, sp, #S_OFF 279 bl syscall_trace_enter 280 281 badr lr, __sys_trace_return @ return address 282 mov scno, r0 @ syscall number (possibly new) 283 add r1, sp, #S_R0 + S_OFF @ pointer to regs 284 cmp scno, #NR_syscalls @ check upper syscall limit 285 ldmccia r1, {r0 - r6} @ have to reload r0 - r6 286 stmccia sp, {r4, r5} @ and update the stack args 287 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 288 cmp scno, #-1 @ skip the syscall? 289 bne 2b 290 add sp, sp, #S_OFF @ restore stack 291 b ret_slow_syscall 292 293__sys_trace_return: 294 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 295 mov r0, sp 296 bl syscall_trace_exit 297 b ret_slow_syscall 298 299__sys_trace_return_nosave: 300 enable_irq_notrace 301 mov r0, sp 302 bl syscall_trace_exit 303 b ret_slow_syscall 304 305 .align 5 306#ifdef CONFIG_ALIGNMENT_TRAP 307 .type __cr_alignment, #object 308__cr_alignment: 309 .word cr_alignment 310#endif 311 .ltorg 312 313 .macro syscall_table_start, sym 314 .equ __sys_nr, 0 315 .type \sym, #object 316ENTRY(\sym) 317 .endm 318 319 .macro syscall, nr, func 320 .ifgt __sys_nr - \nr 321 .error "Duplicated/unorded system call entry" 322 .endif 323 .rept \nr - __sys_nr 324 .long sys_ni_syscall 325 .endr 326 .long \func 327 .equ __sys_nr, \nr + 1 328 .endm 329 330 .macro syscall_table_end, sym 331 .ifgt __sys_nr - __NR_syscalls 332 .error "System call table too big" 333 .endif 334 .rept __NR_syscalls - __sys_nr 335 .long sys_ni_syscall 336 .endr 337 .size \sym, . - \sym 338 .endm 339 340#define NATIVE(nr, func) syscall nr, func 341 342/* 343 * This is the syscall table declaration for native ABI syscalls. 344 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 345 */ 346 syscall_table_start sys_call_table 347#define COMPAT(nr, native, compat) syscall nr, native 348#ifdef CONFIG_AEABI 349#include <calls-eabi.S> 350#else 351#include <calls-oabi.S> 352#endif 353#undef COMPAT 354 syscall_table_end sys_call_table 355 356/*============================================================================ 357 * Special system call wrappers 358 */ 359@ r0 = syscall number 360@ r8 = syscall table 361sys_syscall: 362 bic scno, r0, #__NR_OABI_SYSCALL_BASE 363 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 364 cmpne scno, #NR_syscalls @ check range 365 stmloia sp, {r5, r6} @ shuffle args 366 movlo r0, r1 367 movlo r1, r2 368 movlo r2, r3 369 movlo r3, r4 370 ldrlo pc, [tbl, scno, lsl #2] 371 b sys_ni_syscall 372ENDPROC(sys_syscall) 373 374sys_sigreturn_wrapper: 375 add r0, sp, #S_OFF 376 mov why, #0 @ prevent syscall restart handling 377 b sys_sigreturn 378ENDPROC(sys_sigreturn_wrapper) 379 380sys_rt_sigreturn_wrapper: 381 add r0, sp, #S_OFF 382 mov why, #0 @ prevent syscall restart handling 383 b sys_rt_sigreturn 384ENDPROC(sys_rt_sigreturn_wrapper) 385 386sys_statfs64_wrapper: 387 teq r1, #88 388 moveq r1, #84 389 b sys_statfs64 390ENDPROC(sys_statfs64_wrapper) 391 392sys_fstatfs64_wrapper: 393 teq r1, #88 394 moveq r1, #84 395 b sys_fstatfs64 396ENDPROC(sys_fstatfs64_wrapper) 397 398/* 399 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 400 * offset, we return EINVAL. 401 */ 402sys_mmap2: 403 str r5, [sp, #4] 404 b sys_mmap_pgoff 405ENDPROC(sys_mmap2) 406 407#ifdef CONFIG_OABI_COMPAT 408 409/* 410 * These are syscalls with argument register differences 411 */ 412 413sys_oabi_pread64: 414 stmia sp, {r3, r4} 415 b sys_pread64 416ENDPROC(sys_oabi_pread64) 417 418sys_oabi_pwrite64: 419 stmia sp, {r3, r4} 420 b sys_pwrite64 421ENDPROC(sys_oabi_pwrite64) 422 423sys_oabi_truncate64: 424 mov r3, r2 425 mov r2, r1 426 b sys_truncate64 427ENDPROC(sys_oabi_truncate64) 428 429sys_oabi_ftruncate64: 430 mov r3, r2 431 mov r2, r1 432 b sys_ftruncate64 433ENDPROC(sys_oabi_ftruncate64) 434 435sys_oabi_readahead: 436 str r3, [sp] 437 mov r3, r2 438 mov r2, r1 439 b sys_readahead 440ENDPROC(sys_oabi_readahead) 441 442/* 443 * Let's declare a second syscall table for old ABI binaries 444 * using the compatibility syscall entries. 445 */ 446 syscall_table_start sys_oabi_call_table 447#define COMPAT(nr, native, compat) syscall nr, compat 448#include <calls-oabi.S> 449 syscall_table_end sys_oabi_call_table 450 451#endif 452 453