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 reload_current r10, ip 174 zero_fp 175 alignment_trap r10, ip, __cr_alignment 176 asm_trace_hardirqs_on save=0 177 enable_irq_notrace 178 ct_user_exit save=0 179 180 /* 181 * Get the system call number. 182 */ 183 184#if defined(CONFIG_OABI_COMPAT) 185 186 /* 187 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 188 * value to determine if it is an EABI or an old ABI call. 189 */ 190#ifdef CONFIG_ARM_THUMB 191 tst saved_psr, #PSR_T_BIT 192 movne r10, #0 @ no thumb OABI emulation 193 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction 194#else 195 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction 196#endif 197 ARM_BE8(rev r10, r10) @ little endian instruction 198 199#elif defined(CONFIG_AEABI) 200 201 /* 202 * Pure EABI user space always put syscall number into scno (r7). 203 */ 204#elif defined(CONFIG_ARM_THUMB) 205 /* Legacy ABI only, possibly thumb mode. */ 206 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs 207 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 208 USER( ldreq scno, [saved_pc, #-4] ) 209 210#else 211 /* Legacy ABI only. */ 212 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction 213#endif 214 215 /* saved_psr and saved_pc are now dead */ 216 217 uaccess_disable tbl 218 get_thread_info tsk 219 220 adr tbl, sys_call_table @ load syscall table pointer 221 222#if defined(CONFIG_OABI_COMPAT) 223 /* 224 * If the swi argument is zero, this is an EABI call and we do nothing. 225 * 226 * If this is an old ABI call, get the syscall number into scno and 227 * get the old ABI syscall table address. 228 */ 229 bics r10, r10, #0xff000000 230 strne r10, [tsk, #TI_ABI_SYSCALL] 231 streq scno, [tsk, #TI_ABI_SYSCALL] 232 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 233 ldrne tbl, =sys_oabi_call_table 234#elif !defined(CONFIG_AEABI) 235 bic scno, scno, #0xff000000 @ mask off SWI op-code 236 str scno, [tsk, #TI_ABI_SYSCALL] 237 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 238#else 239 str scno, [tsk, #TI_ABI_SYSCALL] 240#endif 241 /* 242 * Reload the registers that may have been corrupted on entry to 243 * the syscall assembly (by tracing or context tracking.) 244 */ 245 TRACE( ldmia sp, {r0 - r3} ) 246 247local_restart: 248 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 249 stmdb sp!, {r4, r5} @ push fifth and sixth args 250 251 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 252 bne __sys_trace 253 254 invoke_syscall tbl, scno, r10, __ret_fast_syscall 255 256 add r1, sp, #S_OFF 2572: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 258 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 259 bcs arm_syscall 260 mov why, #0 @ no longer a real syscall 261 b sys_ni_syscall @ not private func 262 263#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 264 /* 265 * We failed to handle a fault trying to access the page 266 * containing the swi instruction, but we're not really in a 267 * position to return -EFAULT. Instead, return back to the 268 * instruction and re-enter the user fault handling path trying 269 * to page it in. This will likely result in sending SEGV to the 270 * current task. 271 */ 2729001: 273 sub lr, saved_pc, #4 274 str lr, [sp, #S_PC] 275 get_thread_info tsk 276 b ret_fast_syscall 277#endif 278ENDPROC(vector_swi) 279 280 /* 281 * This is the really slow path. We're going to be doing 282 * context switches, and waiting for our parent to respond. 283 */ 284__sys_trace: 285 add r0, sp, #S_OFF 286 bl syscall_trace_enter 287 mov scno, r0 288 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1 289 cmp scno, #-1 @ skip the syscall? 290 bne 2b 291 add sp, sp, #S_OFF @ restore stack 292 293__sys_trace_return_nosave: 294 enable_irq_notrace 295 mov r0, sp 296 bl syscall_trace_exit 297 b ret_slow_syscall 298 299__sys_trace_return: 300 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 301 mov r0, sp 302 bl syscall_trace_exit 303 b ret_slow_syscall 304 305 .align 5 306#ifdef CONFIG_ALIGNMENT_TRAP 307 .type __cr_alignment, #object 308__cr_alignment: 309 .word cr_alignment 310#endif 311 .ltorg 312 313 .macro syscall_table_start, sym 314 .equ __sys_nr, 0 315 .type \sym, #object 316ENTRY(\sym) 317 .endm 318 319 .macro syscall, nr, func 320 .ifgt __sys_nr - \nr 321 .error "Duplicated/unorded system call entry" 322 .endif 323 .rept \nr - __sys_nr 324 .long sys_ni_syscall 325 .endr 326 .long \func 327 .equ __sys_nr, \nr + 1 328 .endm 329 330 .macro syscall_table_end, sym 331 .ifgt __sys_nr - __NR_syscalls 332 .error "System call table too big" 333 .endif 334 .rept __NR_syscalls - __sys_nr 335 .long sys_ni_syscall 336 .endr 337 .size \sym, . - \sym 338 .endm 339 340#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native) 341#define __SYSCALL(nr, func) syscall nr, func 342 343/* 344 * This is the syscall table declaration for native ABI syscalls. 345 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 346 */ 347 syscall_table_start sys_call_table 348#ifdef CONFIG_AEABI 349#include <calls-eabi.S> 350#else 351#include <calls-oabi.S> 352#endif 353 syscall_table_end sys_call_table 354 355/*============================================================================ 356 * Special system call wrappers 357 */ 358@ r0 = syscall number 359@ r8 = syscall table 360sys_syscall: 361 bic scno, r0, #__NR_OABI_SYSCALL_BASE 362 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 363 cmpne scno, #NR_syscalls @ check range 364#ifdef CONFIG_CPU_SPECTRE 365 movhs scno, #0 366 csdb 367#endif 368 stmialo sp, {r5, r6} @ shuffle args 369 movlo r0, r1 370 movlo r1, r2 371 movlo r2, r3 372 movlo r3, r4 373 ldrlo pc, [tbl, scno, lsl #2] 374 b sys_ni_syscall 375ENDPROC(sys_syscall) 376 377sys_sigreturn_wrapper: 378 add r0, sp, #S_OFF 379 mov why, #0 @ prevent syscall restart handling 380 b sys_sigreturn 381ENDPROC(sys_sigreturn_wrapper) 382 383sys_rt_sigreturn_wrapper: 384 add r0, sp, #S_OFF 385 mov why, #0 @ prevent syscall restart handling 386 b sys_rt_sigreturn 387ENDPROC(sys_rt_sigreturn_wrapper) 388 389sys_statfs64_wrapper: 390 teq r1, #88 391 moveq r1, #84 392 b sys_statfs64 393ENDPROC(sys_statfs64_wrapper) 394 395sys_fstatfs64_wrapper: 396 teq r1, #88 397 moveq r1, #84 398 b sys_fstatfs64 399ENDPROC(sys_fstatfs64_wrapper) 400 401/* 402 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 403 * offset, we return EINVAL. 404 */ 405sys_mmap2: 406 str r5, [sp, #4] 407 b sys_mmap_pgoff 408ENDPROC(sys_mmap2) 409 410#ifdef CONFIG_OABI_COMPAT 411 412/* 413 * These are syscalls with argument register differences 414 */ 415 416sys_oabi_pread64: 417 stmia sp, {r3, r4} 418 b sys_pread64 419ENDPROC(sys_oabi_pread64) 420 421sys_oabi_pwrite64: 422 stmia sp, {r3, r4} 423 b sys_pwrite64 424ENDPROC(sys_oabi_pwrite64) 425 426sys_oabi_truncate64: 427 mov r3, r2 428 mov r2, r1 429 b sys_truncate64 430ENDPROC(sys_oabi_truncate64) 431 432sys_oabi_ftruncate64: 433 mov r3, r2 434 mov r2, r1 435 b sys_ftruncate64 436ENDPROC(sys_oabi_ftruncate64) 437 438sys_oabi_readahead: 439 str r3, [sp] 440 mov r3, r2 441 mov r2, r1 442 b sys_readahead 443ENDPROC(sys_oabi_readahead) 444 445/* 446 * Let's declare a second syscall table for old ABI binaries 447 * using the compatibility syscall entries. 448 */ 449 syscall_table_start sys_oabi_call_table 450#undef __SYSCALL_WITH_COMPAT 451#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat) 452#include <calls-oabi.S> 453 syscall_table_end sys_oabi_call_table 454 455#endif 456 457