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/* 44 * This is the fast syscall return path. We do as little as possible here, 45 * such as avoiding writing r0 to the stack. We only use this path if we 46 * have tracing and context tracking disabled - the overheads from those 47 * features make this path too inefficient. 48 */ 49ret_fast_syscall: 50 UNWIND(.fnstart ) 51 UNWIND(.cantunwind ) 52 disable_irq_notrace @ disable interrupts 53 ldr r2, [tsk, #TI_ADDR_LIMIT] 54 cmp r2, #TASK_SIZE 55 blne addr_limit_check_failed 56 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 57 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK 58 bne fast_work_pending 59 60 61 /* perform architecture specific actions before user return */ 62 arch_ret_to_user r1, lr 63 64 restore_user_regs fast = 1, offset = S_OFF 65 UNWIND(.fnend ) 66ENDPROC(ret_fast_syscall) 67 68 /* Ok, we need to do extra processing, enter the slow path. */ 69fast_work_pending: 70 str r0, [sp, #S_R0+S_OFF]! @ returned r0 71 /* fall through to work_pending */ 72#else 73/* 74 * The "replacement" ret_fast_syscall for when tracing or context tracking 75 * is enabled. As we will need to call out to some C functions, we save 76 * r0 first to avoid needing to save registers around each C function call. 77 */ 78ret_fast_syscall: 79 UNWIND(.fnstart ) 80 UNWIND(.cantunwind ) 81 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 82 disable_irq_notrace @ disable interrupts 83 ldr r2, [tsk, #TI_ADDR_LIMIT] 84 cmp r2, #TASK_SIZE 85 blne addr_limit_check_failed 86 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 87 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK 88 beq no_work_pending 89 UNWIND(.fnend ) 90ENDPROC(ret_fast_syscall) 91 92 /* Slower path - fall through to work_pending */ 93#endif 94 95 tst r1, #_TIF_SYSCALL_WORK 96 bne __sys_trace_return_nosave 97slow_work_pending: 98 mov r0, sp @ 'regs' 99 mov r2, why @ 'syscall' 100 bl do_work_pending 101 cmp r0, #0 102 beq no_work_pending 103 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) 104 ldmia sp, {r0 - r6} @ have to reload r0 - r6 105 b local_restart @ ... and off we go 106ENDPROC(ret_fast_syscall) 107 108/* 109 * "slow" syscall return path. "why" tells us if this was a real syscall. 110 * IRQs may be enabled here, so always disable them. Note that we use the 111 * "notrace" version to avoid calling into the tracing code unnecessarily. 112 * do_work_pending() will update this state if necessary. 113 */ 114ENTRY(ret_to_user) 115ret_slow_syscall: 116 disable_irq_notrace @ disable interrupts 117ENTRY(ret_to_user_from_irq) 118 ldr r2, [tsk, #TI_ADDR_LIMIT] 119 cmp r2, #TASK_SIZE 120 blne addr_limit_check_failed 121 ldr r1, [tsk, #TI_FLAGS] 122 tst r1, #_TIF_WORK_MASK 123 bne slow_work_pending 124no_work_pending: 125 asm_trace_hardirqs_on save = 0 126 127 /* perform architecture specific actions before user return */ 128 arch_ret_to_user r1, lr 129 ct_user_enter save = 0 130 131 restore_user_regs fast = 0, offset = 0 132ENDPROC(ret_to_user_from_irq) 133ENDPROC(ret_to_user) 134 135/* 136 * This is how we return from a fork. 137 */ 138ENTRY(ret_from_fork) 139 bl schedule_tail 140 cmp r5, #0 141 movne r0, r4 142 badrne lr, 1f 143 retne r5 1441: get_thread_info tsk 145 b ret_slow_syscall 146ENDPROC(ret_from_fork) 147 148/*============================================================================= 149 * SWI handler 150 *----------------------------------------------------------------------------- 151 */ 152 153 .align 5 154ENTRY(vector_swi) 155#ifdef CONFIG_CPU_V7M 156 v7m_exception_entry 157#else 158 sub sp, sp, #PT_REGS_SIZE 159 stmia sp, {r0 - r12} @ Calling r0 - r12 160 ARM( add r8, sp, #S_PC ) 161 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 162 THUMB( mov r8, sp ) 163 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 164 mrs saved_psr, spsr @ called from non-FIQ mode, so ok. 165 TRACE( mov saved_pc, lr ) 166 str saved_pc, [sp, #S_PC] @ Save calling PC 167 str saved_psr, [sp, #S_PSR] @ Save CPSR 168 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 169#endif 170 zero_fp 171 alignment_trap r10, ip, __cr_alignment 172 asm_trace_hardirqs_on save=0 173 enable_irq_notrace 174 ct_user_exit save=0 175 176 /* 177 * Get the system call number. 178 */ 179 180#if defined(CONFIG_OABI_COMPAT) 181 182 /* 183 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 184 * value to determine if it is an EABI or an old ABI call. 185 */ 186#ifdef CONFIG_ARM_THUMB 187 tst saved_psr, #PSR_T_BIT 188 movne r10, #0 @ no thumb OABI emulation 189 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction 190#else 191 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction 192#endif 193 ARM_BE8(rev r10, r10) @ little endian instruction 194 195#elif defined(CONFIG_AEABI) 196 197 /* 198 * Pure EABI user space always put syscall number into scno (r7). 199 */ 200#elif defined(CONFIG_ARM_THUMB) 201 /* Legacy ABI only, possibly thumb mode. */ 202 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs 203 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 204 USER( ldreq scno, [saved_pc, #-4] ) 205 206#else 207 /* Legacy ABI only. */ 208 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction 209#endif 210 211 /* saved_psr and saved_pc are now dead */ 212 213 uaccess_disable tbl 214 215 adr tbl, sys_call_table @ load syscall table pointer 216 217#if defined(CONFIG_OABI_COMPAT) 218 /* 219 * If the swi argument is zero, this is an EABI call and we do nothing. 220 * 221 * If this is an old ABI call, get the syscall number into scno and 222 * get the old ABI syscall table address. 223 */ 224 bics r10, r10, #0xff000000 225 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 226 ldrne tbl, =sys_oabi_call_table 227#elif !defined(CONFIG_AEABI) 228 bic scno, scno, #0xff000000 @ mask off SWI op-code 229 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 230#endif 231 get_thread_info tsk 232 /* 233 * Reload the registers that may have been corrupted on entry to 234 * the syscall assembly (by tracing or context tracking.) 235 */ 236 TRACE( ldmia sp, {r0 - r3} ) 237 238local_restart: 239 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 240 stmdb sp!, {r4, r5} @ push fifth and sixth args 241 242 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 243 bne __sys_trace 244 245 invoke_syscall tbl, scno, r10, ret_fast_syscall 246 247 add r1, sp, #S_OFF 2482: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 249 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 250 bcs arm_syscall 251 mov why, #0 @ no longer a real syscall 252 b sys_ni_syscall @ not private func 253 254#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 255 /* 256 * We failed to handle a fault trying to access the page 257 * containing the swi instruction, but we're not really in a 258 * position to return -EFAULT. Instead, return back to the 259 * instruction and re-enter the user fault handling path trying 260 * to page it in. This will likely result in sending SEGV to the 261 * current task. 262 */ 2639001: 264 sub lr, saved_pc, #4 265 str lr, [sp, #S_PC] 266 get_thread_info tsk 267 b ret_fast_syscall 268#endif 269ENDPROC(vector_swi) 270 271 /* 272 * This is the really slow path. We're going to be doing 273 * context switches, and waiting for our parent to respond. 274 */ 275__sys_trace: 276 mov r1, scno 277 add r0, sp, #S_OFF 278 bl syscall_trace_enter 279 mov scno, r0 280 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1 281 cmp scno, #-1 @ skip the syscall? 282 bne 2b 283 add sp, sp, #S_OFF @ restore stack 284 b ret_slow_syscall 285 286__sys_trace_return: 287 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 288 mov r0, sp 289 bl syscall_trace_exit 290 b ret_slow_syscall 291 292__sys_trace_return_nosave: 293 enable_irq_notrace 294 mov r0, sp 295 bl syscall_trace_exit 296 b ret_slow_syscall 297 298 .align 5 299#ifdef CONFIG_ALIGNMENT_TRAP 300 .type __cr_alignment, #object 301__cr_alignment: 302 .word cr_alignment 303#endif 304 .ltorg 305 306 .macro syscall_table_start, sym 307 .equ __sys_nr, 0 308 .type \sym, #object 309ENTRY(\sym) 310 .endm 311 312 .macro syscall, nr, func 313 .ifgt __sys_nr - \nr 314 .error "Duplicated/unorded system call entry" 315 .endif 316 .rept \nr - __sys_nr 317 .long sys_ni_syscall 318 .endr 319 .long \func 320 .equ __sys_nr, \nr + 1 321 .endm 322 323 .macro syscall_table_end, sym 324 .ifgt __sys_nr - __NR_syscalls 325 .error "System call table too big" 326 .endif 327 .rept __NR_syscalls - __sys_nr 328 .long sys_ni_syscall 329 .endr 330 .size \sym, . - \sym 331 .endm 332 333#define NATIVE(nr, func) syscall nr, func 334 335/* 336 * This is the syscall table declaration for native ABI syscalls. 337 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 338 */ 339 syscall_table_start sys_call_table 340#define COMPAT(nr, native, compat) syscall nr, native 341#ifdef CONFIG_AEABI 342#include <calls-eabi.S> 343#else 344#include <calls-oabi.S> 345#endif 346#undef COMPAT 347 syscall_table_end sys_call_table 348 349/*============================================================================ 350 * Special system call wrappers 351 */ 352@ r0 = syscall number 353@ r8 = syscall table 354sys_syscall: 355 bic scno, r0, #__NR_OABI_SYSCALL_BASE 356 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 357 cmpne scno, #NR_syscalls @ check range 358#ifdef CONFIG_CPU_SPECTRE 359 movhs scno, #0 360 csdb 361#endif 362 stmloia sp, {r5, r6} @ shuffle args 363 movlo r0, r1 364 movlo r1, r2 365 movlo r2, r3 366 movlo r3, r4 367 ldrlo pc, [tbl, scno, lsl #2] 368 b sys_ni_syscall 369ENDPROC(sys_syscall) 370 371sys_sigreturn_wrapper: 372 add r0, sp, #S_OFF 373 mov why, #0 @ prevent syscall restart handling 374 b sys_sigreturn 375ENDPROC(sys_sigreturn_wrapper) 376 377sys_rt_sigreturn_wrapper: 378 add r0, sp, #S_OFF 379 mov why, #0 @ prevent syscall restart handling 380 b sys_rt_sigreturn 381ENDPROC(sys_rt_sigreturn_wrapper) 382 383sys_statfs64_wrapper: 384 teq r1, #88 385 moveq r1, #84 386 b sys_statfs64 387ENDPROC(sys_statfs64_wrapper) 388 389sys_fstatfs64_wrapper: 390 teq r1, #88 391 moveq r1, #84 392 b sys_fstatfs64 393ENDPROC(sys_fstatfs64_wrapper) 394 395/* 396 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 397 * offset, we return EINVAL. 398 */ 399sys_mmap2: 400 str r5, [sp, #4] 401 b sys_mmap_pgoff 402ENDPROC(sys_mmap2) 403 404#ifdef CONFIG_OABI_COMPAT 405 406/* 407 * These are syscalls with argument register differences 408 */ 409 410sys_oabi_pread64: 411 stmia sp, {r3, r4} 412 b sys_pread64 413ENDPROC(sys_oabi_pread64) 414 415sys_oabi_pwrite64: 416 stmia sp, {r3, r4} 417 b sys_pwrite64 418ENDPROC(sys_oabi_pwrite64) 419 420sys_oabi_truncate64: 421 mov r3, r2 422 mov r2, r1 423 b sys_truncate64 424ENDPROC(sys_oabi_truncate64) 425 426sys_oabi_ftruncate64: 427 mov r3, r2 428 mov r2, r1 429 b sys_ftruncate64 430ENDPROC(sys_oabi_ftruncate64) 431 432sys_oabi_readahead: 433 str r3, [sp] 434 mov r3, r2 435 mov r2, r1 436 b sys_readahead 437ENDPROC(sys_oabi_readahead) 438 439/* 440 * Let's declare a second syscall table for old ABI binaries 441 * using the compatibility syscall entries. 442 */ 443 syscall_table_start sys_oabi_call_table 444#define COMPAT(nr, native, compat) syscall nr, compat 445#include <calls-oabi.S> 446 syscall_table_end sys_oabi_call_table 447 448#endif 449 450