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 r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 53 movs r1, r1, lsl #16 54 bne fast_work_pending 55 56 57 /* perform architecture specific actions before user return */ 58 arch_ret_to_user r1, lr 59 60 restore_user_regs fast = 1, offset = S_OFF 61 UNWIND(.fnend ) 62ENDPROC(ret_fast_syscall) 63 64 /* Ok, we need to do extra processing, enter the slow path. */ 65fast_work_pending: 66 str r0, [sp, #S_R0+S_OFF]! @ returned r0 67 /* fall through to work_pending */ 68#else 69/* 70 * The "replacement" ret_fast_syscall for when tracing, context tracking, 71 * or rseq debug is enabled. As we will need to call out to some C functions, 72 * we save r0 first to avoid needing to save registers around each C function 73 * call. 74 */ 75ret_fast_syscall: 76__ret_fast_syscall: 77 UNWIND(.fnstart ) 78 UNWIND(.cantunwind ) 79 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 80#if IS_ENABLED(CONFIG_DEBUG_RSEQ) 81 /* do_rseq_syscall needs interrupts enabled. */ 82 mov r0, sp @ 'regs' 83 bl do_rseq_syscall 84#endif 85 disable_irq_notrace @ disable interrupts 86 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 87 movs r1, r1, lsl #16 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#if IS_ENABLED(CONFIG_DEBUG_RSEQ) 117 /* do_rseq_syscall needs interrupts enabled. */ 118 enable_irq_notrace @ enable interrupts 119 mov r0, sp @ 'regs' 120 bl do_rseq_syscall 121#endif 122 disable_irq_notrace @ disable interrupts 123ENTRY(ret_to_user_from_irq) 124 ldr r1, [tsk, #TI_FLAGS] 125 movs r1, r1, lsl #16 126 bne slow_work_pending 127no_work_pending: 128 asm_trace_hardirqs_on save = 0 129 130 /* perform architecture specific actions before user return */ 131 arch_ret_to_user r1, lr 132 ct_user_enter save = 0 133 134 restore_user_regs fast = 0, offset = 0 135ENDPROC(ret_to_user_from_irq) 136ENDPROC(ret_to_user) 137 138/* 139 * This is how we return from a fork. 140 */ 141ENTRY(ret_from_fork) 142 bl schedule_tail 143 cmp r5, #0 144 movne r0, r4 145 badrne lr, 1f 146 retne r5 1471: get_thread_info tsk 148 b ret_slow_syscall 149ENDPROC(ret_from_fork) 150 151/*============================================================================= 152 * SWI handler 153 *----------------------------------------------------------------------------- 154 */ 155 156 .align 5 157ENTRY(vector_swi) 158#ifdef CONFIG_CPU_V7M 159 v7m_exception_entry 160#else 161 sub sp, sp, #PT_REGS_SIZE 162 stmia sp, {r0 - r12} @ Calling r0 - r12 163 ARM( add r8, sp, #S_PC ) 164 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 165 THUMB( mov r8, sp ) 166 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 167 mrs saved_psr, spsr @ called from non-FIQ mode, so ok. 168 TRACE( mov saved_pc, lr ) 169 str saved_pc, [sp, #S_PC] @ Save calling PC 170 str saved_psr, [sp, #S_PSR] @ Save CPSR 171 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 172#endif 173 zero_fp 174 alignment_trap r10, ip, __cr_alignment 175 asm_trace_hardirqs_on save=0 176 enable_irq_notrace 177 ct_user_exit save=0 178 179 /* 180 * Get the system call number. 181 */ 182 183#if defined(CONFIG_OABI_COMPAT) 184 185 /* 186 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 187 * value to determine if it is an EABI or an old ABI call. 188 */ 189#ifdef CONFIG_ARM_THUMB 190 tst saved_psr, #PSR_T_BIT 191 movne r10, #0 @ no thumb OABI emulation 192 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction 193#else 194 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction 195#endif 196 ARM_BE8(rev r10, r10) @ little endian instruction 197 198#elif defined(CONFIG_AEABI) 199 200 /* 201 * Pure EABI user space always put syscall number into scno (r7). 202 */ 203#elif defined(CONFIG_ARM_THUMB) 204 /* Legacy ABI only, possibly thumb mode. */ 205 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs 206 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 207 USER( ldreq scno, [saved_pc, #-4] ) 208 209#else 210 /* Legacy ABI only. */ 211 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction 212#endif 213 214 /* saved_psr and saved_pc are now dead */ 215 216 uaccess_disable tbl 217 get_thread_info tsk 218 219 adr tbl, sys_call_table @ load syscall table pointer 220 221#if defined(CONFIG_OABI_COMPAT) 222 /* 223 * If the swi argument is zero, this is an EABI call and we do nothing. 224 * 225 * If this is an old ABI call, get the syscall number into scno and 226 * get the old ABI syscall table address. 227 */ 228 bics r10, r10, #0xff000000 229 strne r10, [tsk, #TI_ABI_SYSCALL] 230 streq scno, [tsk, #TI_ABI_SYSCALL] 231 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 232 ldrne tbl, =sys_oabi_call_table 233#elif !defined(CONFIG_AEABI) 234 bic scno, scno, #0xff000000 @ mask off SWI op-code 235 str scno, [tsk, #TI_ABI_SYSCALL] 236 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 237#else 238 str scno, [tsk, #TI_ABI_SYSCALL] 239#endif 240 /* 241 * Reload the registers that may have been corrupted on entry to 242 * the syscall assembly (by tracing or context tracking.) 243 */ 244 TRACE( ldmia sp, {r0 - r3} ) 245 246local_restart: 247 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 248 stmdb sp!, {r4, r5} @ push fifth and sixth args 249 250 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 251 bne __sys_trace 252 253 invoke_syscall tbl, scno, r10, __ret_fast_syscall 254 255 add r1, sp, #S_OFF 2562: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 257 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 258 bcs arm_syscall 259 mov why, #0 @ no longer a real syscall 260 b sys_ni_syscall @ not private func 261 262#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 263 /* 264 * We failed to handle a fault trying to access the page 265 * containing the swi instruction, but we're not really in a 266 * position to return -EFAULT. Instead, return back to the 267 * instruction and re-enter the user fault handling path trying 268 * to page it in. This will likely result in sending SEGV to the 269 * current task. 270 */ 2719001: 272 sub lr, saved_pc, #4 273 str lr, [sp, #S_PC] 274 get_thread_info tsk 275 b ret_fast_syscall 276#endif 277ENDPROC(vector_swi) 278 279 /* 280 * This is the really slow path. We're going to be doing 281 * context switches, and waiting for our parent to respond. 282 */ 283__sys_trace: 284 add r0, sp, #S_OFF 285 bl syscall_trace_enter 286 mov scno, r0 287 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1 288 cmp scno, #-1 @ skip the syscall? 289 bne 2b 290 add sp, sp, #S_OFF @ restore stack 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__sys_trace_return: 299 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 300 mov r0, sp 301 bl syscall_trace_exit 302 b ret_slow_syscall 303 304 .align 5 305#ifdef CONFIG_ALIGNMENT_TRAP 306 .type __cr_alignment, #object 307__cr_alignment: 308 .word cr_alignment 309#endif 310 .ltorg 311 312 .macro syscall_table_start, sym 313 .equ __sys_nr, 0 314 .type \sym, #object 315ENTRY(\sym) 316 .endm 317 318 .macro syscall, nr, func 319 .ifgt __sys_nr - \nr 320 .error "Duplicated/unorded system call entry" 321 .endif 322 .rept \nr - __sys_nr 323 .long sys_ni_syscall 324 .endr 325 .long \func 326 .equ __sys_nr, \nr + 1 327 .endm 328 329 .macro syscall_table_end, sym 330 .ifgt __sys_nr - __NR_syscalls 331 .error "System call table too big" 332 .endif 333 .rept __NR_syscalls - __sys_nr 334 .long sys_ni_syscall 335 .endr 336 .size \sym, . - \sym 337 .endm 338 339#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native) 340#define __SYSCALL(nr, func) syscall nr, func 341 342/* 343 * This is the syscall table declaration for native ABI syscalls. 344 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 345 */ 346 syscall_table_start sys_call_table 347#ifdef CONFIG_AEABI 348#include <calls-eabi.S> 349#else 350#include <calls-oabi.S> 351#endif 352 syscall_table_end sys_call_table 353 354/*============================================================================ 355 * Special system call wrappers 356 */ 357@ r0 = syscall number 358@ r8 = syscall table 359sys_syscall: 360 bic scno, r0, #__NR_OABI_SYSCALL_BASE 361 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 362 cmpne scno, #NR_syscalls @ check range 363#ifdef CONFIG_CPU_SPECTRE 364 movhs scno, #0 365 csdb 366#endif 367 stmialo sp, {r5, r6} @ shuffle args 368 movlo r0, r1 369 movlo r1, r2 370 movlo r2, r3 371 movlo r3, r4 372 ldrlo pc, [tbl, scno, lsl #2] 373 b sys_ni_syscall 374ENDPROC(sys_syscall) 375 376sys_sigreturn_wrapper: 377 add r0, sp, #S_OFF 378 mov why, #0 @ prevent syscall restart handling 379 b sys_sigreturn 380ENDPROC(sys_sigreturn_wrapper) 381 382sys_rt_sigreturn_wrapper: 383 add r0, sp, #S_OFF 384 mov why, #0 @ prevent syscall restart handling 385 b sys_rt_sigreturn 386ENDPROC(sys_rt_sigreturn_wrapper) 387 388sys_statfs64_wrapper: 389 teq r1, #88 390 moveq r1, #84 391 b sys_statfs64 392ENDPROC(sys_statfs64_wrapper) 393 394sys_fstatfs64_wrapper: 395 teq r1, #88 396 moveq r1, #84 397 b sys_fstatfs64 398ENDPROC(sys_fstatfs64_wrapper) 399 400/* 401 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 402 * offset, we return EINVAL. 403 */ 404sys_mmap2: 405 str r5, [sp, #4] 406 b sys_mmap_pgoff 407ENDPROC(sys_mmap2) 408 409#ifdef CONFIG_OABI_COMPAT 410 411/* 412 * These are syscalls with argument register differences 413 */ 414 415sys_oabi_pread64: 416 stmia sp, {r3, r4} 417 b sys_pread64 418ENDPROC(sys_oabi_pread64) 419 420sys_oabi_pwrite64: 421 stmia sp, {r3, r4} 422 b sys_pwrite64 423ENDPROC(sys_oabi_pwrite64) 424 425sys_oabi_truncate64: 426 mov r3, r2 427 mov r2, r1 428 b sys_truncate64 429ENDPROC(sys_oabi_truncate64) 430 431sys_oabi_ftruncate64: 432 mov r3, r2 433 mov r2, r1 434 b sys_ftruncate64 435ENDPROC(sys_oabi_ftruncate64) 436 437sys_oabi_readahead: 438 str r3, [sp] 439 mov r3, r2 440 mov r2, r1 441 b sys_readahead 442ENDPROC(sys_oabi_readahead) 443 444/* 445 * Let's declare a second syscall table for old ABI binaries 446 * using the compatibility syscall entries. 447 */ 448 syscall_table_start sys_oabi_call_table 449#undef __SYSCALL_WITH_COMPAT 450#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat) 451#include <calls-oabi.S> 452 syscall_table_end sys_oabi_call_table 453 454#endif 455 456