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 .section .entry.text,"ax",%progbits 41 .align 5 42#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING) || \ 43 IS_ENABLED(CONFIG_DEBUG_RSEQ)) 44/* 45 * This is the fast syscall return path. We do as little as possible here, 46 * such as avoiding writing r0 to the stack. We only use this path if we 47 * have tracing, context tracking and rseq debug disabled - the overheads 48 * from those features make this path too inefficient. 49 */ 50ret_fast_syscall: 51__ret_fast_syscall: 52 UNWIND(.fnstart ) 53 UNWIND(.cantunwind ) 54 disable_irq_notrace @ disable interrupts 55 ldr r2, [tsk, #TI_ADDR_LIMIT] 56 cmp r2, #TASK_SIZE 57 blne addr_limit_check_failed 58 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 59 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK 60 bne fast_work_pending 61 62 63 /* perform architecture specific actions before user return */ 64 arch_ret_to_user r1, lr 65 66 restore_user_regs fast = 1, offset = S_OFF 67 UNWIND(.fnend ) 68ENDPROC(ret_fast_syscall) 69 70 /* Ok, we need to do extra processing, enter the slow path. */ 71fast_work_pending: 72 str r0, [sp, #S_R0+S_OFF]! @ returned r0 73 /* fall through to work_pending */ 74#else 75/* 76 * The "replacement" ret_fast_syscall for when tracing, context tracking, 77 * or rseq debug is enabled. As we will need to call out to some C functions, 78 * we save r0 first to avoid needing to save registers around each C function 79 * call. 80 */ 81ret_fast_syscall: 82__ret_fast_syscall: 83 UNWIND(.fnstart ) 84 UNWIND(.cantunwind ) 85 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 86#if IS_ENABLED(CONFIG_DEBUG_RSEQ) 87 /* do_rseq_syscall needs interrupts enabled. */ 88 mov r0, sp @ 'regs' 89 bl do_rseq_syscall 90#endif 91 disable_irq_notrace @ disable interrupts 92 ldr r2, [tsk, #TI_ADDR_LIMIT] 93 cmp r2, #TASK_SIZE 94 blne addr_limit_check_failed 95 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 96 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK 97 beq no_work_pending 98 UNWIND(.fnend ) 99ENDPROC(ret_fast_syscall) 100 101 /* Slower path - fall through to work_pending */ 102#endif 103 104 tst r1, #_TIF_SYSCALL_WORK 105 bne __sys_trace_return_nosave 106slow_work_pending: 107 mov r0, sp @ 'regs' 108 mov r2, why @ 'syscall' 109 bl do_work_pending 110 cmp r0, #0 111 beq no_work_pending 112 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) 113 ldmia sp, {r0 - r6} @ have to reload r0 - r6 114 b local_restart @ ... and off we go 115ENDPROC(ret_fast_syscall) 116 117/* 118 * "slow" syscall return path. "why" tells us if this was a real syscall. 119 * IRQs may be enabled here, so always disable them. Note that we use the 120 * "notrace" version to avoid calling into the tracing code unnecessarily. 121 * do_work_pending() will update this state if necessary. 122 */ 123ENTRY(ret_to_user) 124ret_slow_syscall: 125#if IS_ENABLED(CONFIG_DEBUG_RSEQ) 126 /* do_rseq_syscall needs interrupts enabled. */ 127 enable_irq_notrace @ enable interrupts 128 mov r0, sp @ 'regs' 129 bl do_rseq_syscall 130#endif 131 disable_irq_notrace @ disable interrupts 132ENTRY(ret_to_user_from_irq) 133 ldr r2, [tsk, #TI_ADDR_LIMIT] 134 cmp r2, #TASK_SIZE 135 blne addr_limit_check_failed 136 ldr r1, [tsk, #TI_FLAGS] 137 tst r1, #_TIF_WORK_MASK 138 bne slow_work_pending 139no_work_pending: 140 asm_trace_hardirqs_on save = 0 141 142 /* perform architecture specific actions before user return */ 143 arch_ret_to_user r1, lr 144 ct_user_enter save = 0 145 146 restore_user_regs fast = 0, offset = 0 147ENDPROC(ret_to_user_from_irq) 148ENDPROC(ret_to_user) 149 150/* 151 * This is how we return from a fork. 152 */ 153ENTRY(ret_from_fork) 154 bl schedule_tail 155 cmp r5, #0 156 movne r0, r4 157 badrne lr, 1f 158 retne r5 1591: get_thread_info tsk 160 b ret_slow_syscall 161ENDPROC(ret_from_fork) 162 163/*============================================================================= 164 * SWI handler 165 *----------------------------------------------------------------------------- 166 */ 167 168 .align 5 169ENTRY(vector_swi) 170#ifdef CONFIG_CPU_V7M 171 v7m_exception_entry 172#else 173 sub sp, sp, #PT_REGS_SIZE 174 stmia sp, {r0 - r12} @ Calling r0 - r12 175 ARM( add r8, sp, #S_PC ) 176 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 177 THUMB( mov r8, sp ) 178 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 179 mrs saved_psr, spsr @ called from non-FIQ mode, so ok. 180 TRACE( mov saved_pc, lr ) 181 str saved_pc, [sp, #S_PC] @ Save calling PC 182 str saved_psr, [sp, #S_PSR] @ Save CPSR 183 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 184#endif 185 zero_fp 186 alignment_trap r10, ip, __cr_alignment 187 asm_trace_hardirqs_on save=0 188 enable_irq_notrace 189 ct_user_exit save=0 190 191 /* 192 * Get the system call number. 193 */ 194 195#if defined(CONFIG_OABI_COMPAT) 196 197 /* 198 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 199 * value to determine if it is an EABI or an old ABI call. 200 */ 201#ifdef CONFIG_ARM_THUMB 202 tst saved_psr, #PSR_T_BIT 203 movne r10, #0 @ no thumb OABI emulation 204 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction 205#else 206 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction 207#endif 208 ARM_BE8(rev r10, r10) @ little endian instruction 209 210#elif defined(CONFIG_AEABI) 211 212 /* 213 * Pure EABI user space always put syscall number into scno (r7). 214 */ 215#elif defined(CONFIG_ARM_THUMB) 216 /* Legacy ABI only, possibly thumb mode. */ 217 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs 218 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 219 USER( ldreq scno, [saved_pc, #-4] ) 220 221#else 222 /* Legacy ABI only. */ 223 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction 224#endif 225 226 /* saved_psr and saved_pc are now dead */ 227 228 uaccess_disable tbl 229 230 adr tbl, sys_call_table @ load syscall table pointer 231 232#if defined(CONFIG_OABI_COMPAT) 233 /* 234 * If the swi argument is zero, this is an EABI call and we do nothing. 235 * 236 * If this is an old ABI call, get the syscall number into scno and 237 * get the old ABI syscall table address. 238 */ 239 bics r10, r10, #0xff000000 240 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 241 ldrne tbl, =sys_oabi_call_table 242#elif !defined(CONFIG_AEABI) 243 bic scno, scno, #0xff000000 @ mask off SWI op-code 244 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 245#endif 246 get_thread_info tsk 247 /* 248 * Reload the registers that may have been corrupted on entry to 249 * the syscall assembly (by tracing or context tracking.) 250 */ 251 TRACE( ldmia sp, {r0 - r3} ) 252 253local_restart: 254 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 255 stmdb sp!, {r4, r5} @ push fifth and sixth args 256 257 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 258 bne __sys_trace 259 260 invoke_syscall tbl, scno, r10, __ret_fast_syscall 261 262 add r1, sp, #S_OFF 2632: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 264 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 265 bcs arm_syscall 266 mov why, #0 @ no longer a real syscall 267 b sys_ni_syscall @ not private func 268 269#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 270 /* 271 * We failed to handle a fault trying to access the page 272 * containing the swi instruction, but we're not really in a 273 * position to return -EFAULT. Instead, return back to the 274 * instruction and re-enter the user fault handling path trying 275 * to page it in. This will likely result in sending SEGV to the 276 * current task. 277 */ 2789001: 279 sub lr, saved_pc, #4 280 str lr, [sp, #S_PC] 281 get_thread_info tsk 282 b ret_fast_syscall 283#endif 284ENDPROC(vector_swi) 285 286 /* 287 * This is the really slow path. We're going to be doing 288 * context switches, and waiting for our parent to respond. 289 */ 290__sys_trace: 291 mov r1, scno 292 add r0, sp, #S_OFF 293 bl syscall_trace_enter 294 mov scno, r0 295 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1 296 cmp scno, #-1 @ skip the syscall? 297 bne 2b 298 add sp, sp, #S_OFF @ restore stack 299 b ret_slow_syscall 300 301__sys_trace_return: 302 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 303 mov r0, sp 304 bl syscall_trace_exit 305 b ret_slow_syscall 306 307__sys_trace_return_nosave: 308 enable_irq_notrace 309 mov r0, sp 310 bl syscall_trace_exit 311 b ret_slow_syscall 312 313 .align 5 314#ifdef CONFIG_ALIGNMENT_TRAP 315 .type __cr_alignment, #object 316__cr_alignment: 317 .word cr_alignment 318#endif 319 .ltorg 320 321 .macro syscall_table_start, sym 322 .equ __sys_nr, 0 323 .type \sym, #object 324ENTRY(\sym) 325 .endm 326 327 .macro syscall, nr, func 328 .ifgt __sys_nr - \nr 329 .error "Duplicated/unorded system call entry" 330 .endif 331 .rept \nr - __sys_nr 332 .long sys_ni_syscall 333 .endr 334 .long \func 335 .equ __sys_nr, \nr + 1 336 .endm 337 338 .macro syscall_table_end, sym 339 .ifgt __sys_nr - __NR_syscalls 340 .error "System call table too big" 341 .endif 342 .rept __NR_syscalls - __sys_nr 343 .long sys_ni_syscall 344 .endr 345 .size \sym, . - \sym 346 .endm 347 348#define NATIVE(nr, func) syscall nr, func 349 350/* 351 * This is the syscall table declaration for native ABI syscalls. 352 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 353 */ 354 syscall_table_start sys_call_table 355#define COMPAT(nr, native, compat) syscall nr, native 356#ifdef CONFIG_AEABI 357#include <calls-eabi.S> 358#else 359#include <calls-oabi.S> 360#endif 361#undef COMPAT 362 syscall_table_end sys_call_table 363 364/*============================================================================ 365 * Special system call wrappers 366 */ 367@ r0 = syscall number 368@ r8 = syscall table 369sys_syscall: 370 bic scno, r0, #__NR_OABI_SYSCALL_BASE 371 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 372 cmpne scno, #NR_syscalls @ check range 373#ifdef CONFIG_CPU_SPECTRE 374 movhs scno, #0 375 csdb 376#endif 377 stmloia sp, {r5, r6} @ shuffle args 378 movlo r0, r1 379 movlo r1, r2 380 movlo r2, r3 381 movlo r3, r4 382 ldrlo pc, [tbl, scno, lsl #2] 383 b sys_ni_syscall 384ENDPROC(sys_syscall) 385 386sys_sigreturn_wrapper: 387 add r0, sp, #S_OFF 388 mov why, #0 @ prevent syscall restart handling 389 b sys_sigreturn 390ENDPROC(sys_sigreturn_wrapper) 391 392sys_rt_sigreturn_wrapper: 393 add r0, sp, #S_OFF 394 mov why, #0 @ prevent syscall restart handling 395 b sys_rt_sigreturn 396ENDPROC(sys_rt_sigreturn_wrapper) 397 398sys_statfs64_wrapper: 399 teq r1, #88 400 moveq r1, #84 401 b sys_statfs64 402ENDPROC(sys_statfs64_wrapper) 403 404sys_fstatfs64_wrapper: 405 teq r1, #88 406 moveq r1, #84 407 b sys_fstatfs64 408ENDPROC(sys_fstatfs64_wrapper) 409 410/* 411 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 412 * offset, we return EINVAL. 413 */ 414sys_mmap2: 415 str r5, [sp, #4] 416 b sys_mmap_pgoff 417ENDPROC(sys_mmap2) 418 419#ifdef CONFIG_OABI_COMPAT 420 421/* 422 * These are syscalls with argument register differences 423 */ 424 425sys_oabi_pread64: 426 stmia sp, {r3, r4} 427 b sys_pread64 428ENDPROC(sys_oabi_pread64) 429 430sys_oabi_pwrite64: 431 stmia sp, {r3, r4} 432 b sys_pwrite64 433ENDPROC(sys_oabi_pwrite64) 434 435sys_oabi_truncate64: 436 mov r3, r2 437 mov r2, r1 438 b sys_truncate64 439ENDPROC(sys_oabi_truncate64) 440 441sys_oabi_ftruncate64: 442 mov r3, r2 443 mov r2, r1 444 b sys_ftruncate64 445ENDPROC(sys_oabi_ftruncate64) 446 447sys_oabi_readahead: 448 str r3, [sp] 449 mov r3, r2 450 mov r2, r1 451 b sys_readahead 452ENDPROC(sys_oabi_readahead) 453 454/* 455 * Let's declare a second syscall table for old ABI binaries 456 * using the compatibility syscall entries. 457 */ 458 syscall_table_start sys_oabi_call_table 459#define COMPAT(nr, native, compat) syscall nr, compat 460#include <calls-oabi.S> 461 syscall_table_end sys_oabi_call_table 462 463#endif 464 465