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 ldr r1, =TASK_SIZE 54 cmp r2, r1 55 blne addr_limit_check_failed 56 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 57 movs r1, r1, lsl #16 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, context tracking, 75 * or rseq debug is enabled. As we will need to call out to some C functions, 76 * we save r0 first to avoid needing to save registers around each C function 77 * call. 78 */ 79ret_fast_syscall: 80__ret_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 ldr r1, =TASK_SIZE 92 cmp r2, r1 93 blne addr_limit_check_failed 94 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 95 movs r1, r1, lsl #16 96 beq no_work_pending 97 UNWIND(.fnend ) 98ENDPROC(ret_fast_syscall) 99 100 /* Slower path - fall through to work_pending */ 101#endif 102 103 tst r1, #_TIF_SYSCALL_WORK 104 bne __sys_trace_return_nosave 105slow_work_pending: 106 mov r0, sp @ 'regs' 107 mov r2, why @ 'syscall' 108 bl do_work_pending 109 cmp r0, #0 110 beq no_work_pending 111 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) 112 ldmia sp, {r0 - r6} @ have to reload r0 - r6 113 b local_restart @ ... and off we go 114ENDPROC(ret_fast_syscall) 115 116/* 117 * "slow" syscall return path. "why" tells us if this was a real syscall. 118 * IRQs may be enabled here, so always disable them. Note that we use the 119 * "notrace" version to avoid calling into the tracing code unnecessarily. 120 * do_work_pending() will update this state if necessary. 121 */ 122ENTRY(ret_to_user) 123ret_slow_syscall: 124#if IS_ENABLED(CONFIG_DEBUG_RSEQ) 125 /* do_rseq_syscall needs interrupts enabled. */ 126 enable_irq_notrace @ enable interrupts 127 mov r0, sp @ 'regs' 128 bl do_rseq_syscall 129#endif 130 disable_irq_notrace @ disable interrupts 131ENTRY(ret_to_user_from_irq) 132 ldr r2, [tsk, #TI_ADDR_LIMIT] 133 ldr r1, =TASK_SIZE 134 cmp r2, r1 135 blne addr_limit_check_failed 136 ldr r1, [tsk, #TI_FLAGS] 137 movs r1, r1, lsl #16 138 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 5 169#ifdef CONFIG_HARDEN_BRANCH_HISTORY 170ENTRY(vector_bhb_loop8_swi) 171 sub sp, sp, #PT_REGS_SIZE 172 stmia sp, {r0 - r12} 173 mov r8, #8 1741: b 2f 1752: subs r8, r8, #1 176 bne 1b 177 dsb 178 isb 179 b 3f 180ENDPROC(vector_bhb_loop8_swi) 181 182 .align 5 183ENTRY(vector_bhb_bpiall_swi) 184 sub sp, sp, #PT_REGS_SIZE 185 stmia sp, {r0 - r12} 186 mcr p15, 0, r8, c7, c5, 6 @ BPIALL 187 isb 188 b 3f 189ENDPROC(vector_bhb_bpiall_swi) 190#endif 191 .align 5 192ENTRY(vector_swi) 193#ifdef CONFIG_CPU_V7M 194 v7m_exception_entry 195#else 196 sub sp, sp, #PT_REGS_SIZE 197 stmia sp, {r0 - r12} @ Calling r0 - r12 1983: 199 ARM( add r8, sp, #S_PC ) 200 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 201 THUMB( mov r8, sp ) 202 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 203 mrs saved_psr, spsr @ called from non-FIQ mode, so ok. 204 TRACE( mov saved_pc, lr ) 205 str saved_pc, [sp, #S_PC] @ Save calling PC 206 str saved_psr, [sp, #S_PSR] @ Save CPSR 207 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 208#endif 209 zero_fp 210 alignment_trap r10, ip, __cr_alignment 211 asm_trace_hardirqs_on save=0 212 enable_irq_notrace 213 ct_user_exit save=0 214 215 /* 216 * Get the system call number. 217 */ 218 219#if defined(CONFIG_OABI_COMPAT) 220 221 /* 222 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 223 * value to determine if it is an EABI or an old ABI call. 224 */ 225#ifdef CONFIG_ARM_THUMB 226 tst saved_psr, #PSR_T_BIT 227 movne r10, #0 @ no thumb OABI emulation 228 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction 229#else 230 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction 231#endif 232 ARM_BE8(rev r10, r10) @ little endian instruction 233 234#elif defined(CONFIG_AEABI) 235 236 /* 237 * Pure EABI user space always put syscall number into scno (r7). 238 */ 239#elif defined(CONFIG_ARM_THUMB) 240 /* Legacy ABI only, possibly thumb mode. */ 241 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs 242 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 243 USER( ldreq scno, [saved_pc, #-4] ) 244 245#else 246 /* Legacy ABI only. */ 247 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction 248#endif 249 250 /* saved_psr and saved_pc are now dead */ 251 252 uaccess_disable tbl 253 254 adr tbl, sys_call_table @ load syscall table pointer 255 256#if defined(CONFIG_OABI_COMPAT) 257 /* 258 * If the swi argument is zero, this is an EABI call and we do nothing. 259 * 260 * If this is an old ABI call, get the syscall number into scno and 261 * get the old ABI syscall table address. 262 */ 263 bics r10, r10, #0xff000000 264 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 265 ldrne tbl, =sys_oabi_call_table 266#elif !defined(CONFIG_AEABI) 267 bic scno, scno, #0xff000000 @ mask off SWI op-code 268 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 269#endif 270 get_thread_info tsk 271 /* 272 * Reload the registers that may have been corrupted on entry to 273 * the syscall assembly (by tracing or context tracking.) 274 */ 275 TRACE( ldmia sp, {r0 - r3} ) 276 277local_restart: 278 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 279 stmdb sp!, {r4, r5} @ push fifth and sixth args 280 281 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 282 bne __sys_trace 283 284 invoke_syscall tbl, scno, r10, __ret_fast_syscall 285 286 add r1, sp, #S_OFF 2872: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 288 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 289 bcs arm_syscall 290 mov why, #0 @ no longer a real syscall 291 b sys_ni_syscall @ not private func 292 293#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 294 /* 295 * We failed to handle a fault trying to access the page 296 * containing the swi instruction, but we're not really in a 297 * position to return -EFAULT. Instead, return back to the 298 * instruction and re-enter the user fault handling path trying 299 * to page it in. This will likely result in sending SEGV to the 300 * current task. 301 */ 3029001: 303 sub lr, saved_pc, #4 304 str lr, [sp, #S_PC] 305 get_thread_info tsk 306 b ret_fast_syscall 307#endif 308ENDPROC(vector_swi) 309 310 /* 311 * This is the really slow path. We're going to be doing 312 * context switches, and waiting for our parent to respond. 313 */ 314__sys_trace: 315 mov r1, scno 316 add r0, sp, #S_OFF 317 bl syscall_trace_enter 318 mov scno, r0 319 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1 320 cmp scno, #-1 @ skip the syscall? 321 bne 2b 322 add sp, sp, #S_OFF @ restore stack 323 324__sys_trace_return_nosave: 325 enable_irq_notrace 326 mov r0, sp 327 bl syscall_trace_exit 328 b ret_slow_syscall 329 330__sys_trace_return: 331 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 332 mov r0, sp 333 bl syscall_trace_exit 334 b ret_slow_syscall 335 336 .align 5 337#ifdef CONFIG_ALIGNMENT_TRAP 338 .type __cr_alignment, #object 339__cr_alignment: 340 .word cr_alignment 341#endif 342 .ltorg 343 344 .macro syscall_table_start, sym 345 .equ __sys_nr, 0 346 .type \sym, #object 347ENTRY(\sym) 348 .endm 349 350 .macro syscall, nr, func 351 .ifgt __sys_nr - \nr 352 .error "Duplicated/unorded system call entry" 353 .endif 354 .rept \nr - __sys_nr 355 .long sys_ni_syscall 356 .endr 357 .long \func 358 .equ __sys_nr, \nr + 1 359 .endm 360 361 .macro syscall_table_end, sym 362 .ifgt __sys_nr - __NR_syscalls 363 .error "System call table too big" 364 .endif 365 .rept __NR_syscalls - __sys_nr 366 .long sys_ni_syscall 367 .endr 368 .size \sym, . - \sym 369 .endm 370 371#define NATIVE(nr, func) syscall nr, func 372 373/* 374 * This is the syscall table declaration for native ABI syscalls. 375 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 376 */ 377 syscall_table_start sys_call_table 378#define COMPAT(nr, native, compat) syscall nr, native 379#ifdef CONFIG_AEABI 380#include <calls-eabi.S> 381#else 382#include <calls-oabi.S> 383#endif 384#undef COMPAT 385 syscall_table_end sys_call_table 386 387/*============================================================================ 388 * Special system call wrappers 389 */ 390@ r0 = syscall number 391@ r8 = syscall table 392sys_syscall: 393 bic scno, r0, #__NR_OABI_SYSCALL_BASE 394 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 395 cmpne scno, #NR_syscalls @ check range 396#ifdef CONFIG_CPU_SPECTRE 397 movhs scno, #0 398 csdb 399#endif 400 stmialo sp, {r5, r6} @ shuffle args 401 movlo r0, r1 402 movlo r1, r2 403 movlo r2, r3 404 movlo r3, r4 405 ldrlo pc, [tbl, scno, lsl #2] 406 b sys_ni_syscall 407ENDPROC(sys_syscall) 408 409sys_sigreturn_wrapper: 410 add r0, sp, #S_OFF 411 mov why, #0 @ prevent syscall restart handling 412 b sys_sigreturn 413ENDPROC(sys_sigreturn_wrapper) 414 415sys_rt_sigreturn_wrapper: 416 add r0, sp, #S_OFF 417 mov why, #0 @ prevent syscall restart handling 418 b sys_rt_sigreturn 419ENDPROC(sys_rt_sigreturn_wrapper) 420 421sys_statfs64_wrapper: 422 teq r1, #88 423 moveq r1, #84 424 b sys_statfs64 425ENDPROC(sys_statfs64_wrapper) 426 427sys_fstatfs64_wrapper: 428 teq r1, #88 429 moveq r1, #84 430 b sys_fstatfs64 431ENDPROC(sys_fstatfs64_wrapper) 432 433/* 434 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 435 * offset, we return EINVAL. 436 */ 437sys_mmap2: 438 str r5, [sp, #4] 439 b sys_mmap_pgoff 440ENDPROC(sys_mmap2) 441 442#ifdef CONFIG_OABI_COMPAT 443 444/* 445 * These are syscalls with argument register differences 446 */ 447 448sys_oabi_pread64: 449 stmia sp, {r3, r4} 450 b sys_pread64 451ENDPROC(sys_oabi_pread64) 452 453sys_oabi_pwrite64: 454 stmia sp, {r3, r4} 455 b sys_pwrite64 456ENDPROC(sys_oabi_pwrite64) 457 458sys_oabi_truncate64: 459 mov r3, r2 460 mov r2, r1 461 b sys_truncate64 462ENDPROC(sys_oabi_truncate64) 463 464sys_oabi_ftruncate64: 465 mov r3, r2 466 mov r2, r1 467 b sys_ftruncate64 468ENDPROC(sys_oabi_ftruncate64) 469 470sys_oabi_readahead: 471 str r3, [sp] 472 mov r3, r2 473 mov r2, r1 474 b sys_readahead 475ENDPROC(sys_oabi_readahead) 476 477/* 478 * Let's declare a second syscall table for old ABI binaries 479 * using the compatibility syscall entries. 480 */ 481 syscall_table_start sys_oabi_call_table 482#define COMPAT(nr, native, compat) syscall nr, compat 483#include <calls-oabi.S> 484 syscall_table_end sys_oabi_call_table 485 486#endif 487 488