1/* SPDX-License-Identifier: GPL-2.0-only */ 2/* 3 * linux/arch/arm/kernel/entry-common.S 4 * 5 * Copyright (C) 2000 Russell King 6 */ 7 8#include <asm/assembler.h> 9#include <asm/unistd.h> 10#include <asm/ftrace.h> 11#include <asm/unwind.h> 12#include <asm/memory.h> 13#ifdef CONFIG_AEABI 14#include <asm/unistd-oabi.h> 15#endif 16 17 .equ NR_syscalls, __NR_syscalls 18 19#ifdef CONFIG_NEED_RET_TO_USER 20#include <mach/entry-macro.S> 21#else 22 .macro arch_ret_to_user, tmp1, tmp2 23 .endm 24#endif 25 26#include "entry-header.S" 27 28saved_psr .req r8 29#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING) 30saved_pc .req r9 31#define TRACE(x...) x 32#else 33saved_pc .req lr 34#define TRACE(x...) 35#endif 36 37 .section .entry.text,"ax",%progbits 38 .align 5 39#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING) || \ 40 IS_ENABLED(CONFIG_DEBUG_RSEQ)) 41/* 42 * This is the fast syscall return path. We do as little as possible here, 43 * such as avoiding writing r0 to the stack. We only use this path if we 44 * have tracing, context tracking and rseq debug disabled - the overheads 45 * from those features make this path too inefficient. 46 */ 47ret_fast_syscall: 48__ret_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, context tracking, 74 * or rseq debug is enabled. As we will need to call out to some C functions, 75 * we save r0 first to avoid needing to save registers around each C function 76 * 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#if IS_ENABLED(CONFIG_DEBUG_RSEQ) 84 /* do_rseq_syscall needs interrupts enabled. */ 85 mov r0, sp @ 'regs' 86 bl do_rseq_syscall 87#endif 88 disable_irq_notrace @ disable interrupts 89 ldr r2, [tsk, #TI_ADDR_LIMIT] 90 cmp r2, #TASK_SIZE 91 blne addr_limit_check_failed 92 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 93 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK 94 beq no_work_pending 95 UNWIND(.fnend ) 96ENDPROC(ret_fast_syscall) 97 98 /* Slower path - fall through to work_pending */ 99#endif 100 101 tst r1, #_TIF_SYSCALL_WORK 102 bne __sys_trace_return_nosave 103slow_work_pending: 104 mov r0, sp @ 'regs' 105 mov r2, why @ 'syscall' 106 bl do_work_pending 107 cmp r0, #0 108 beq no_work_pending 109 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) 110 ldmia sp, {r0 - r6} @ have to reload r0 - r6 111 b local_restart @ ... and off we go 112ENDPROC(ret_fast_syscall) 113 114/* 115 * "slow" syscall return path. "why" tells us if this was a real syscall. 116 * IRQs may be enabled here, so always disable them. Note that we use the 117 * "notrace" version to avoid calling into the tracing code unnecessarily. 118 * do_work_pending() will update this state if necessary. 119 */ 120ENTRY(ret_to_user) 121ret_slow_syscall: 122#if IS_ENABLED(CONFIG_DEBUG_RSEQ) 123 /* do_rseq_syscall needs interrupts enabled. */ 124 enable_irq_notrace @ enable interrupts 125 mov r0, sp @ 'regs' 126 bl do_rseq_syscall 127#endif 128 disable_irq_notrace @ disable interrupts 129ENTRY(ret_to_user_from_irq) 130 ldr r2, [tsk, #TI_ADDR_LIMIT] 131 cmp r2, #TASK_SIZE 132 blne addr_limit_check_failed 133 ldr r1, [tsk, #TI_FLAGS] 134 tst r1, #_TIF_WORK_MASK 135 bne slow_work_pending 136no_work_pending: 137 asm_trace_hardirqs_on save = 0 138 139 /* perform architecture specific actions before user return */ 140 arch_ret_to_user r1, lr 141 ct_user_enter save = 0 142 143 restore_user_regs fast = 0, offset = 0 144ENDPROC(ret_to_user_from_irq) 145ENDPROC(ret_to_user) 146 147/* 148 * This is how we return from a fork. 149 */ 150ENTRY(ret_from_fork) 151 bl schedule_tail 152 cmp r5, #0 153 movne r0, r4 154 badrne lr, 1f 155 retne r5 1561: get_thread_info tsk 157 b ret_slow_syscall 158ENDPROC(ret_from_fork) 159 160/*============================================================================= 161 * SWI handler 162 *----------------------------------------------------------------------------- 163 */ 164 165 .align 5 166#ifdef CONFIG_HARDEN_BRANCH_HISTORY 167ENTRY(vector_bhb_loop8_swi) 168 sub sp, sp, #PT_REGS_SIZE 169 stmia sp, {r0 - r12} 170 mov r8, #8 1711: b 2f 1722: subs r8, r8, #1 173 bne 1b 174 dsb 175 isb 176 b 3f 177ENDPROC(vector_bhb_loop8_swi) 178 179 .align 5 180ENTRY(vector_bhb_bpiall_swi) 181 sub sp, sp, #PT_REGS_SIZE 182 stmia sp, {r0 - r12} 183 mcr p15, 0, r8, c7, c5, 6 @ BPIALL 184 isb 185 b 3f 186ENDPROC(vector_bhb_bpiall_swi) 187#endif 188 .align 5 189ENTRY(vector_swi) 190#ifdef CONFIG_CPU_V7M 191 v7m_exception_entry 192#else 193 sub sp, sp, #PT_REGS_SIZE 194 stmia sp, {r0 - r12} @ Calling r0 - r12 1953: 196 ARM( add r8, sp, #S_PC ) 197 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 198 THUMB( mov r8, sp ) 199 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 200 mrs saved_psr, spsr @ called from non-FIQ mode, so ok. 201 TRACE( mov saved_pc, lr ) 202 str saved_pc, [sp, #S_PC] @ Save calling PC 203 str saved_psr, [sp, #S_PSR] @ Save CPSR 204 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 205#endif 206 zero_fp 207 alignment_trap r10, ip, __cr_alignment 208 asm_trace_hardirqs_on save=0 209 enable_irq_notrace 210 ct_user_exit save=0 211 212 /* 213 * Get the system call number. 214 */ 215 216#if defined(CONFIG_OABI_COMPAT) 217 218 /* 219 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 220 * value to determine if it is an EABI or an old ABI call. 221 */ 222#ifdef CONFIG_ARM_THUMB 223 tst saved_psr, #PSR_T_BIT 224 movne r10, #0 @ no thumb OABI emulation 225 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction 226#else 227 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction 228#endif 229 ARM_BE8(rev r10, r10) @ little endian instruction 230 231#elif defined(CONFIG_AEABI) 232 233 /* 234 * Pure EABI user space always put syscall number into scno (r7). 235 */ 236#elif defined(CONFIG_ARM_THUMB) 237 /* Legacy ABI only, possibly thumb mode. */ 238 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs 239 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 240 USER( ldreq scno, [saved_pc, #-4] ) 241 242#else 243 /* Legacy ABI only. */ 244 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction 245#endif 246 247 /* saved_psr and saved_pc are now dead */ 248 249 uaccess_disable tbl 250 251 adr tbl, sys_call_table @ load syscall table pointer 252 253#if defined(CONFIG_OABI_COMPAT) 254 /* 255 * If the swi argument is zero, this is an EABI call and we do nothing. 256 * 257 * If this is an old ABI call, get the syscall number into scno and 258 * get the old ABI syscall table address. 259 */ 260 bics r10, r10, #0xff000000 261 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 262 ldrne tbl, =sys_oabi_call_table 263#elif !defined(CONFIG_AEABI) 264 bic scno, scno, #0xff000000 @ mask off SWI op-code 265 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 266#endif 267 get_thread_info tsk 268 /* 269 * Reload the registers that may have been corrupted on entry to 270 * the syscall assembly (by tracing or context tracking.) 271 */ 272 TRACE( ldmia sp, {r0 - r3} ) 273 274local_restart: 275 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 276 stmdb sp!, {r4, r5} @ push fifth and sixth args 277 278 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 279 bne __sys_trace 280 281 invoke_syscall tbl, scno, r10, __ret_fast_syscall 282 283 add r1, sp, #S_OFF 2842: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 285 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 286 bcs arm_syscall 287 mov why, #0 @ no longer a real syscall 288 b sys_ni_syscall @ not private func 289 290#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 291 /* 292 * We failed to handle a fault trying to access the page 293 * containing the swi instruction, but we're not really in a 294 * position to return -EFAULT. Instead, return back to the 295 * instruction and re-enter the user fault handling path trying 296 * to page it in. This will likely result in sending SEGV to the 297 * current task. 298 */ 2999001: 300 sub lr, saved_pc, #4 301 str lr, [sp, #S_PC] 302 get_thread_info tsk 303 b ret_fast_syscall 304#endif 305ENDPROC(vector_swi) 306 307 /* 308 * This is the really slow path. We're going to be doing 309 * context switches, and waiting for our parent to respond. 310 */ 311__sys_trace: 312 mov r1, scno 313 add r0, sp, #S_OFF 314 bl syscall_trace_enter 315 mov scno, r0 316 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1 317 cmp scno, #-1 @ skip the syscall? 318 bne 2b 319 add sp, sp, #S_OFF @ restore stack 320 321__sys_trace_return_nosave: 322 enable_irq_notrace 323 mov r0, sp 324 bl syscall_trace_exit 325 b ret_slow_syscall 326 327__sys_trace_return: 328 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 329 mov r0, sp 330 bl syscall_trace_exit 331 b ret_slow_syscall 332 333 .align 5 334#ifdef CONFIG_ALIGNMENT_TRAP 335 .type __cr_alignment, #object 336__cr_alignment: 337 .word cr_alignment 338#endif 339 .ltorg 340 341 .macro syscall_table_start, sym 342 .equ __sys_nr, 0 343 .type \sym, #object 344ENTRY(\sym) 345 .endm 346 347 .macro syscall, nr, func 348 .ifgt __sys_nr - \nr 349 .error "Duplicated/unorded system call entry" 350 .endif 351 .rept \nr - __sys_nr 352 .long sys_ni_syscall 353 .endr 354 .long \func 355 .equ __sys_nr, \nr + 1 356 .endm 357 358 .macro syscall_table_end, sym 359 .ifgt __sys_nr - __NR_syscalls 360 .error "System call table too big" 361 .endif 362 .rept __NR_syscalls - __sys_nr 363 .long sys_ni_syscall 364 .endr 365 .size \sym, . - \sym 366 .endm 367 368#define NATIVE(nr, func) syscall nr, func 369 370/* 371 * This is the syscall table declaration for native ABI syscalls. 372 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 373 */ 374 syscall_table_start sys_call_table 375#define COMPAT(nr, native, compat) syscall nr, native 376#ifdef CONFIG_AEABI 377#include <calls-eabi.S> 378#else 379#include <calls-oabi.S> 380#endif 381#undef COMPAT 382 syscall_table_end sys_call_table 383 384/*============================================================================ 385 * Special system call wrappers 386 */ 387@ r0 = syscall number 388@ r8 = syscall table 389sys_syscall: 390 bic scno, r0, #__NR_OABI_SYSCALL_BASE 391 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 392 cmpne scno, #NR_syscalls @ check range 393#ifdef CONFIG_CPU_SPECTRE 394 movhs scno, #0 395 csdb 396#endif 397 stmialo sp, {r5, r6} @ shuffle args 398 movlo r0, r1 399 movlo r1, r2 400 movlo r2, r3 401 movlo r3, r4 402 ldrlo pc, [tbl, scno, lsl #2] 403 b sys_ni_syscall 404ENDPROC(sys_syscall) 405 406sys_sigreturn_wrapper: 407 add r0, sp, #S_OFF 408 mov why, #0 @ prevent syscall restart handling 409 b sys_sigreturn 410ENDPROC(sys_sigreturn_wrapper) 411 412sys_rt_sigreturn_wrapper: 413 add r0, sp, #S_OFF 414 mov why, #0 @ prevent syscall restart handling 415 b sys_rt_sigreturn 416ENDPROC(sys_rt_sigreturn_wrapper) 417 418sys_statfs64_wrapper: 419 teq r1, #88 420 moveq r1, #84 421 b sys_statfs64 422ENDPROC(sys_statfs64_wrapper) 423 424sys_fstatfs64_wrapper: 425 teq r1, #88 426 moveq r1, #84 427 b sys_fstatfs64 428ENDPROC(sys_fstatfs64_wrapper) 429 430/* 431 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 432 * offset, we return EINVAL. 433 */ 434sys_mmap2: 435 str r5, [sp, #4] 436 b sys_mmap_pgoff 437ENDPROC(sys_mmap2) 438 439#ifdef CONFIG_OABI_COMPAT 440 441/* 442 * These are syscalls with argument register differences 443 */ 444 445sys_oabi_pread64: 446 stmia sp, {r3, r4} 447 b sys_pread64 448ENDPROC(sys_oabi_pread64) 449 450sys_oabi_pwrite64: 451 stmia sp, {r3, r4} 452 b sys_pwrite64 453ENDPROC(sys_oabi_pwrite64) 454 455sys_oabi_truncate64: 456 mov r3, r2 457 mov r2, r1 458 b sys_truncate64 459ENDPROC(sys_oabi_truncate64) 460 461sys_oabi_ftruncate64: 462 mov r3, r2 463 mov r2, r1 464 b sys_ftruncate64 465ENDPROC(sys_oabi_ftruncate64) 466 467sys_oabi_readahead: 468 str r3, [sp] 469 mov r3, r2 470 mov r2, r1 471 b sys_readahead 472ENDPROC(sys_oabi_readahead) 473 474/* 475 * Let's declare a second syscall table for old ABI binaries 476 * using the compatibility syscall entries. 477 */ 478 syscall_table_start sys_oabi_call_table 479#define COMPAT(nr, native, compat) syscall nr, compat 480#include <calls-oabi.S> 481 syscall_table_end sys_oabi_call_table 482 483#endif 484 485