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__ret_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__ret_fast_syscall: 80 UNWIND(.fnstart ) 81 UNWIND(.cantunwind ) 82 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 83 disable_irq_notrace @ disable interrupts 84 ldr r2, [tsk, #TI_ADDR_LIMIT] 85 cmp r2, #TASK_SIZE 86 blne addr_limit_check_failed 87 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 88 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK 89 beq no_work_pending 90 UNWIND(.fnend ) 91ENDPROC(ret_fast_syscall) 92 93 /* Slower path - fall through to work_pending */ 94#endif 95 96 tst r1, #_TIF_SYSCALL_WORK 97 bne __sys_trace_return_nosave 98slow_work_pending: 99 mov r0, sp @ 'regs' 100 mov r2, why @ 'syscall' 101 bl do_work_pending 102 cmp r0, #0 103 beq no_work_pending 104 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) 105 ldmia sp, {r0 - r6} @ have to reload r0 - r6 106 b local_restart @ ... and off we go 107ENDPROC(ret_fast_syscall) 108 109/* 110 * "slow" syscall return path. "why" tells us if this was a real syscall. 111 * IRQs may be enabled here, so always disable them. Note that we use the 112 * "notrace" version to avoid calling into the tracing code unnecessarily. 113 * do_work_pending() will update this state if necessary. 114 */ 115ENTRY(ret_to_user) 116ret_slow_syscall: 117 disable_irq_notrace @ disable interrupts 118ENTRY(ret_to_user_from_irq) 119 ldr r2, [tsk, #TI_ADDR_LIMIT] 120 cmp r2, #TASK_SIZE 121 blne addr_limit_check_failed 122 ldr r1, [tsk, #TI_FLAGS] 123 tst r1, #_TIF_WORK_MASK 124 bne slow_work_pending 125no_work_pending: 126 asm_trace_hardirqs_on save = 0 127 128 /* perform architecture specific actions before user return */ 129 arch_ret_to_user r1, lr 130 ct_user_enter save = 0 131 132 restore_user_regs fast = 0, offset = 0 133ENDPROC(ret_to_user_from_irq) 134ENDPROC(ret_to_user) 135 136/* 137 * This is how we return from a fork. 138 */ 139ENTRY(ret_from_fork) 140 bl schedule_tail 141 cmp r5, #0 142 movne r0, r4 143 badrne lr, 1f 144 retne r5 1451: get_thread_info tsk 146 b ret_slow_syscall 147ENDPROC(ret_from_fork) 148 149/*============================================================================= 150 * SWI handler 151 *----------------------------------------------------------------------------- 152 */ 153 154 .align 5 155ENTRY(vector_swi) 156#ifdef CONFIG_CPU_V7M 157 v7m_exception_entry 158#else 159 sub sp, sp, #PT_REGS_SIZE 160 stmia sp, {r0 - r12} @ Calling r0 - r12 161 ARM( add r8, sp, #S_PC ) 162 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 163 THUMB( mov r8, sp ) 164 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 165 mrs saved_psr, spsr @ called from non-FIQ mode, so ok. 166 TRACE( mov saved_pc, lr ) 167 str saved_pc, [sp, #S_PC] @ Save calling PC 168 str saved_psr, [sp, #S_PSR] @ Save CPSR 169 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 170#endif 171 zero_fp 172 alignment_trap r10, ip, __cr_alignment 173 asm_trace_hardirqs_on save=0 174 enable_irq_notrace 175 ct_user_exit save=0 176 177 /* 178 * Get the system call number. 179 */ 180 181#if defined(CONFIG_OABI_COMPAT) 182 183 /* 184 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 185 * value to determine if it is an EABI or an old ABI call. 186 */ 187#ifdef CONFIG_ARM_THUMB 188 tst saved_psr, #PSR_T_BIT 189 movne r10, #0 @ no thumb OABI emulation 190 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction 191#else 192 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction 193#endif 194 ARM_BE8(rev r10, r10) @ little endian instruction 195 196#elif defined(CONFIG_AEABI) 197 198 /* 199 * Pure EABI user space always put syscall number into scno (r7). 200 */ 201#elif defined(CONFIG_ARM_THUMB) 202 /* Legacy ABI only, possibly thumb mode. */ 203 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs 204 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 205 USER( ldreq scno, [saved_pc, #-4] ) 206 207#else 208 /* Legacy ABI only. */ 209 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction 210#endif 211 212 /* saved_psr and saved_pc are now dead */ 213 214 uaccess_disable tbl 215 216 adr tbl, sys_call_table @ load syscall table pointer 217 218#if defined(CONFIG_OABI_COMPAT) 219 /* 220 * If the swi argument is zero, this is an EABI call and we do nothing. 221 * 222 * If this is an old ABI call, get the syscall number into scno and 223 * get the old ABI syscall table address. 224 */ 225 bics r10, r10, #0xff000000 226 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 227 ldrne tbl, =sys_oabi_call_table 228#elif !defined(CONFIG_AEABI) 229 bic scno, scno, #0xff000000 @ mask off SWI op-code 230 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 231#endif 232 get_thread_info tsk 233 /* 234 * Reload the registers that may have been corrupted on entry to 235 * the syscall assembly (by tracing or context tracking.) 236 */ 237 TRACE( ldmia sp, {r0 - r3} ) 238 239local_restart: 240 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 241 stmdb sp!, {r4, r5} @ push fifth and sixth args 242 243 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 244 bne __sys_trace 245 246 invoke_syscall tbl, scno, r10, __ret_fast_syscall 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 mov scno, r0 281 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1 282 cmp scno, #-1 @ skip the syscall? 283 bne 2b 284 add sp, sp, #S_OFF @ restore stack 285 286__sys_trace_return_nosave: 287 enable_irq_notrace 288 mov r0, sp 289 bl syscall_trace_exit 290 b ret_slow_syscall 291 292__sys_trace_return: 293 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 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#if PAGE_SHIFT > 12 401 tst r5, #PGOFF_MASK 402 moveq r5, r5, lsr #PAGE_SHIFT - 12 403 streq r5, [sp, #4] 404 beq sys_mmap_pgoff 405 mov r0, #-EINVAL 406 ret lr 407#else 408 str r5, [sp, #4] 409 b sys_mmap_pgoff 410#endif 411ENDPROC(sys_mmap2) 412 413#ifdef CONFIG_OABI_COMPAT 414 415/* 416 * These are syscalls with argument register differences 417 */ 418 419sys_oabi_pread64: 420 stmia sp, {r3, r4} 421 b sys_pread64 422ENDPROC(sys_oabi_pread64) 423 424sys_oabi_pwrite64: 425 stmia sp, {r3, r4} 426 b sys_pwrite64 427ENDPROC(sys_oabi_pwrite64) 428 429sys_oabi_truncate64: 430 mov r3, r2 431 mov r2, r1 432 b sys_truncate64 433ENDPROC(sys_oabi_truncate64) 434 435sys_oabi_ftruncate64: 436 mov r3, r2 437 mov r2, r1 438 b sys_ftruncate64 439ENDPROC(sys_oabi_ftruncate64) 440 441sys_oabi_readahead: 442 str r3, [sp] 443 mov r3, r2 444 mov r2, r1 445 b sys_readahead 446ENDPROC(sys_oabi_readahead) 447 448/* 449 * Let's declare a second syscall table for old ABI binaries 450 * using the compatibility syscall entries. 451 */ 452 syscall_table_start sys_oabi_call_table 453#define COMPAT(nr, native, compat) syscall nr, compat 454#include <calls-oabi.S> 455 syscall_table_end sys_oabi_call_table 456 457#endif 458 459