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 UNWIND(.fnstart ) 52 UNWIND(.cantunwind ) 53 disable_irq_notrace @ disable interrupts 54 ldr r2, [tsk, #TI_ADDR_LIMIT] 55 cmp r2, #TASK_SIZE 56 blne addr_limit_check_failed 57 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 58 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK 59 bne fast_work_pending 60 61 62 /* perform architecture specific actions before user return */ 63 arch_ret_to_user r1, lr 64 65 restore_user_regs fast = 1, offset = S_OFF 66 UNWIND(.fnend ) 67ENDPROC(ret_fast_syscall) 68 69 /* Ok, we need to do extra processing, enter the slow path. */ 70fast_work_pending: 71 str r0, [sp, #S_R0+S_OFF]! @ returned r0 72 /* fall through to work_pending */ 73#else 74/* 75 * The "replacement" ret_fast_syscall for when tracing, context tracking, 76 * or rseq debug is enabled. As we will need to call out to some C functions, 77 * we save r0 first to avoid needing to save registers around each C function 78 * call. 79 */ 80ret_fast_syscall: 81 UNWIND(.fnstart ) 82 UNWIND(.cantunwind ) 83 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 84#if IS_ENABLED(CONFIG_DEBUG_RSEQ) 85 /* do_rseq_syscall needs interrupts enabled. */ 86 mov r0, sp @ 'regs' 87 bl do_rseq_syscall 88#endif 89 disable_irq_notrace @ disable interrupts 90 ldr r2, [tsk, #TI_ADDR_LIMIT] 91 cmp r2, #TASK_SIZE 92 blne addr_limit_check_failed 93 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 94 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK 95 beq no_work_pending 96 UNWIND(.fnend ) 97ENDPROC(ret_fast_syscall) 98 99 /* Slower path - fall through to work_pending */ 100#endif 101 102 tst r1, #_TIF_SYSCALL_WORK 103 bne __sys_trace_return_nosave 104slow_work_pending: 105 mov r0, sp @ 'regs' 106 mov r2, why @ 'syscall' 107 bl do_work_pending 108 cmp r0, #0 109 beq no_work_pending 110 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) 111 ldmia sp, {r0 - r6} @ have to reload r0 - r6 112 b local_restart @ ... and off we go 113ENDPROC(ret_fast_syscall) 114 115/* 116 * "slow" syscall return path. "why" tells us if this was a real syscall. 117 * IRQs may be enabled here, so always disable them. Note that we use the 118 * "notrace" version to avoid calling into the tracing code unnecessarily. 119 * do_work_pending() will update this state if necessary. 120 */ 121ENTRY(ret_to_user) 122ret_slow_syscall: 123#if IS_ENABLED(CONFIG_DEBUG_RSEQ) 124 /* do_rseq_syscall needs interrupts enabled. */ 125 enable_irq_notrace @ enable interrupts 126 mov r0, sp @ 'regs' 127 bl do_rseq_syscall 128#endif 129 disable_irq_notrace @ disable interrupts 130ENTRY(ret_to_user_from_irq) 131 ldr r2, [tsk, #TI_ADDR_LIMIT] 132 cmp r2, #TASK_SIZE 133 blne addr_limit_check_failed 134 ldr r1, [tsk, #TI_FLAGS] 135 tst r1, #_TIF_WORK_MASK 136 bne slow_work_pending 137no_work_pending: 138 asm_trace_hardirqs_on save = 0 139 140 /* perform architecture specific actions before user return */ 141 arch_ret_to_user r1, lr 142 ct_user_enter save = 0 143 144 restore_user_regs fast = 0, offset = 0 145ENDPROC(ret_to_user_from_irq) 146ENDPROC(ret_to_user) 147 148/* 149 * This is how we return from a fork. 150 */ 151ENTRY(ret_from_fork) 152 bl schedule_tail 153 cmp r5, #0 154 movne r0, r4 155 badrne lr, 1f 156 retne r5 1571: get_thread_info tsk 158 b ret_slow_syscall 159ENDPROC(ret_from_fork) 160 161/*============================================================================= 162 * SWI handler 163 *----------------------------------------------------------------------------- 164 */ 165 166 .align 5 167ENTRY(vector_swi) 168#ifdef CONFIG_CPU_V7M 169 v7m_exception_entry 170#else 171 sub sp, sp, #PT_REGS_SIZE 172 stmia sp, {r0 - r12} @ Calling r0 - r12 173 ARM( add r8, sp, #S_PC ) 174 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 175 THUMB( mov r8, sp ) 176 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 177 mrs saved_psr, spsr @ called from non-FIQ mode, so ok. 178 TRACE( mov saved_pc, lr ) 179 str saved_pc, [sp, #S_PC] @ Save calling PC 180 str saved_psr, [sp, #S_PSR] @ Save CPSR 181 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 182#endif 183 zero_fp 184 alignment_trap r10, ip, __cr_alignment 185 asm_trace_hardirqs_on save=0 186 enable_irq_notrace 187 ct_user_exit save=0 188 189 /* 190 * Get the system call number. 191 */ 192 193#if defined(CONFIG_OABI_COMPAT) 194 195 /* 196 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 197 * value to determine if it is an EABI or an old ABI call. 198 */ 199#ifdef CONFIG_ARM_THUMB 200 tst saved_psr, #PSR_T_BIT 201 movne r10, #0 @ no thumb OABI emulation 202 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction 203#else 204 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction 205#endif 206 ARM_BE8(rev r10, r10) @ little endian instruction 207 208#elif defined(CONFIG_AEABI) 209 210 /* 211 * Pure EABI user space always put syscall number into scno (r7). 212 */ 213#elif defined(CONFIG_ARM_THUMB) 214 /* Legacy ABI only, possibly thumb mode. */ 215 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs 216 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 217 USER( ldreq scno, [saved_pc, #-4] ) 218 219#else 220 /* Legacy ABI only. */ 221 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction 222#endif 223 224 /* saved_psr and saved_pc are now dead */ 225 226 uaccess_disable tbl 227 228 adr tbl, sys_call_table @ load syscall table pointer 229 230#if defined(CONFIG_OABI_COMPAT) 231 /* 232 * If the swi argument is zero, this is an EABI call and we do nothing. 233 * 234 * If this is an old ABI call, get the syscall number into scno and 235 * get the old ABI syscall table address. 236 */ 237 bics r10, r10, #0xff000000 238 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 239 ldrne tbl, =sys_oabi_call_table 240#elif !defined(CONFIG_AEABI) 241 bic scno, scno, #0xff000000 @ mask off SWI op-code 242 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 243#endif 244 get_thread_info tsk 245 /* 246 * Reload the registers that may have been corrupted on entry to 247 * the syscall assembly (by tracing or context tracking.) 248 */ 249 TRACE( ldmia sp, {r0 - r3} ) 250 251local_restart: 252 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 253 stmdb sp!, {r4, r5} @ push fifth and sixth args 254 255 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 256 bne __sys_trace 257 258 invoke_syscall tbl, scno, r10, ret_fast_syscall 259 260 add r1, sp, #S_OFF 2612: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 262 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 263 bcs arm_syscall 264 mov why, #0 @ no longer a real syscall 265 b sys_ni_syscall @ not private func 266 267#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 268 /* 269 * We failed to handle a fault trying to access the page 270 * containing the swi instruction, but we're not really in a 271 * position to return -EFAULT. Instead, return back to the 272 * instruction and re-enter the user fault handling path trying 273 * to page it in. This will likely result in sending SEGV to the 274 * current task. 275 */ 2769001: 277 sub lr, saved_pc, #4 278 str lr, [sp, #S_PC] 279 get_thread_info tsk 280 b ret_fast_syscall 281#endif 282ENDPROC(vector_swi) 283 284 /* 285 * This is the really slow path. We're going to be doing 286 * context switches, and waiting for our parent to respond. 287 */ 288__sys_trace: 289 mov r1, scno 290 add r0, sp, #S_OFF 291 bl syscall_trace_enter 292 mov scno, r0 293 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1 294 cmp scno, #-1 @ skip the syscall? 295 bne 2b 296 add sp, sp, #S_OFF @ restore stack 297 b ret_slow_syscall 298 299__sys_trace_return: 300 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 301 mov r0, sp 302 bl syscall_trace_exit 303 b ret_slow_syscall 304 305__sys_trace_return_nosave: 306 enable_irq_notrace 307 mov r0, sp 308 bl syscall_trace_exit 309 b ret_slow_syscall 310 311 .align 5 312#ifdef CONFIG_ALIGNMENT_TRAP 313 .type __cr_alignment, #object 314__cr_alignment: 315 .word cr_alignment 316#endif 317 .ltorg 318 319 .macro syscall_table_start, sym 320 .equ __sys_nr, 0 321 .type \sym, #object 322ENTRY(\sym) 323 .endm 324 325 .macro syscall, nr, func 326 .ifgt __sys_nr - \nr 327 .error "Duplicated/unorded system call entry" 328 .endif 329 .rept \nr - __sys_nr 330 .long sys_ni_syscall 331 .endr 332 .long \func 333 .equ __sys_nr, \nr + 1 334 .endm 335 336 .macro syscall_table_end, sym 337 .ifgt __sys_nr - __NR_syscalls 338 .error "System call table too big" 339 .endif 340 .rept __NR_syscalls - __sys_nr 341 .long sys_ni_syscall 342 .endr 343 .size \sym, . - \sym 344 .endm 345 346#define NATIVE(nr, func) syscall nr, func 347 348/* 349 * This is the syscall table declaration for native ABI syscalls. 350 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 351 */ 352 syscall_table_start sys_call_table 353#define COMPAT(nr, native, compat) syscall nr, native 354#ifdef CONFIG_AEABI 355#include <calls-eabi.S> 356#else 357#include <calls-oabi.S> 358#endif 359#undef COMPAT 360 syscall_table_end sys_call_table 361 362/*============================================================================ 363 * Special system call wrappers 364 */ 365@ r0 = syscall number 366@ r8 = syscall table 367sys_syscall: 368 bic scno, r0, #__NR_OABI_SYSCALL_BASE 369 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 370 cmpne scno, #NR_syscalls @ check range 371#ifdef CONFIG_CPU_SPECTRE 372 movhs scno, #0 373 csdb 374#endif 375 stmloia sp, {r5, r6} @ shuffle args 376 movlo r0, r1 377 movlo r1, r2 378 movlo r2, r3 379 movlo r3, r4 380 ldrlo pc, [tbl, scno, lsl #2] 381 b sys_ni_syscall 382ENDPROC(sys_syscall) 383 384sys_sigreturn_wrapper: 385 add r0, sp, #S_OFF 386 mov why, #0 @ prevent syscall restart handling 387 b sys_sigreturn 388ENDPROC(sys_sigreturn_wrapper) 389 390sys_rt_sigreturn_wrapper: 391 add r0, sp, #S_OFF 392 mov why, #0 @ prevent syscall restart handling 393 b sys_rt_sigreturn 394ENDPROC(sys_rt_sigreturn_wrapper) 395 396sys_statfs64_wrapper: 397 teq r1, #88 398 moveq r1, #84 399 b sys_statfs64 400ENDPROC(sys_statfs64_wrapper) 401 402sys_fstatfs64_wrapper: 403 teq r1, #88 404 moveq r1, #84 405 b sys_fstatfs64 406ENDPROC(sys_fstatfs64_wrapper) 407 408/* 409 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 410 * offset, we return EINVAL. 411 */ 412sys_mmap2: 413 str r5, [sp, #4] 414 b sys_mmap_pgoff 415ENDPROC(sys_mmap2) 416 417#ifdef CONFIG_OABI_COMPAT 418 419/* 420 * These are syscalls with argument register differences 421 */ 422 423sys_oabi_pread64: 424 stmia sp, {r3, r4} 425 b sys_pread64 426ENDPROC(sys_oabi_pread64) 427 428sys_oabi_pwrite64: 429 stmia sp, {r3, r4} 430 b sys_pwrite64 431ENDPROC(sys_oabi_pwrite64) 432 433sys_oabi_truncate64: 434 mov r3, r2 435 mov r2, r1 436 b sys_truncate64 437ENDPROC(sys_oabi_truncate64) 438 439sys_oabi_ftruncate64: 440 mov r3, r2 441 mov r2, r1 442 b sys_ftruncate64 443ENDPROC(sys_oabi_ftruncate64) 444 445sys_oabi_readahead: 446 str r3, [sp] 447 mov r3, r2 448 mov r2, r1 449 b sys_readahead 450ENDPROC(sys_oabi_readahead) 451 452/* 453 * Let's declare a second syscall table for old ABI binaries 454 * using the compatibility syscall entries. 455 */ 456 syscall_table_start sys_oabi_call_table 457#define COMPAT(nr, native, compat) syscall nr, compat 458#include <calls-oabi.S> 459 syscall_table_end sys_oabi_call_table 460 461#endif 462 463