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#include "entry-header.S" 20 21saved_psr .req r8 22#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING_USER) 23saved_pc .req r9 24#define TRACE(x...) x 25#else 26saved_pc .req lr 27#define TRACE(x...) 28#endif 29 30 .section .entry.text,"ax",%progbits 31 .align 5 32#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING_USER) || \ 33 IS_ENABLED(CONFIG_DEBUG_RSEQ)) 34/* 35 * This is the fast syscall return path. We do as little as possible here, 36 * such as avoiding writing r0 to the stack. We only use this path if we 37 * have tracing, context tracking and rseq debug disabled - the overheads 38 * from those features make this path too inefficient. 39 */ 40ret_fast_syscall: 41__ret_fast_syscall: 42 UNWIND(.fnstart ) 43 UNWIND(.cantunwind ) 44 disable_irq_notrace @ disable interrupts 45 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 46 movs r1, r1, lsl #16 47 bne fast_work_pending 48 49 restore_user_regs fast = 1, offset = S_OFF 50 UNWIND(.fnend ) 51ENDPROC(ret_fast_syscall) 52 53 /* Ok, we need to do extra processing, enter the slow path. */ 54fast_work_pending: 55 str r0, [sp, #S_R0+S_OFF]! @ returned r0 56 /* fall through to work_pending */ 57#else 58/* 59 * The "replacement" ret_fast_syscall for when tracing, context tracking, 60 * or rseq debug is enabled. As we will need to call out to some C functions, 61 * we save r0 first to avoid needing to save registers around each C function 62 * call. 63 */ 64ret_fast_syscall: 65__ret_fast_syscall: 66 UNWIND(.fnstart ) 67 UNWIND(.cantunwind ) 68 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 69#if IS_ENABLED(CONFIG_DEBUG_RSEQ) 70 /* do_rseq_syscall needs interrupts enabled. */ 71 mov r0, sp @ 'regs' 72 bl do_rseq_syscall 73#endif 74 disable_irq_notrace @ disable interrupts 75 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 76 movs r1, r1, lsl #16 77 beq no_work_pending 78 UNWIND(.fnend ) 79ENDPROC(ret_fast_syscall) 80 81 /* Slower path - fall through to work_pending */ 82#endif 83 84 tst r1, #_TIF_SYSCALL_WORK 85 bne __sys_trace_return_nosave 86slow_work_pending: 87 mov r0, sp @ 'regs' 88 mov r2, why @ 'syscall' 89 bl do_work_pending 90 cmp r0, #0 91 beq no_work_pending 92 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) 93 ldmia sp, {r0 - r6} @ have to reload r0 - r6 94 b local_restart @ ... and off we go 95ENDPROC(ret_fast_syscall) 96 97/* 98 * "slow" syscall return path. "why" tells us if this was a real syscall. 99 * IRQs may be enabled here, so always disable them. Note that we use the 100 * "notrace" version to avoid calling into the tracing code unnecessarily. 101 * do_work_pending() will update this state if necessary. 102 */ 103ENTRY(ret_to_user) 104ret_slow_syscall: 105#if IS_ENABLED(CONFIG_DEBUG_RSEQ) 106 /* do_rseq_syscall needs interrupts enabled. */ 107 enable_irq_notrace @ enable interrupts 108 mov r0, sp @ 'regs' 109 bl do_rseq_syscall 110#endif 111 disable_irq_notrace @ disable interrupts 112ENTRY(ret_to_user_from_irq) 113 ldr r1, [tsk, #TI_FLAGS] 114 movs r1, r1, lsl #16 115 bne slow_work_pending 116no_work_pending: 117 asm_trace_hardirqs_on save = 0 118 119 ct_user_enter save = 0 120 121 restore_user_regs fast = 0, offset = 0 122ENDPROC(ret_to_user_from_irq) 123ENDPROC(ret_to_user) 124 125/* 126 * This is how we return from a fork. 127 */ 128ENTRY(ret_from_fork) 129 bl schedule_tail 130 cmp r5, #0 131 movne r0, r4 132 badrne lr, 1f 133 retne r5 1341: get_thread_info tsk 135 b ret_slow_syscall 136ENDPROC(ret_from_fork) 137 138/*============================================================================= 139 * SWI handler 140 *----------------------------------------------------------------------------- 141 */ 142 143 .align 5 144#ifdef CONFIG_HARDEN_BRANCH_HISTORY 145ENTRY(vector_bhb_loop8_swi) 146 sub sp, sp, #PT_REGS_SIZE 147 stmia sp, {r0 - r12} 148 mov r8, #8 1491: b 2f 1502: subs r8, r8, #1 151 bne 1b 152 dsb nsh 153 isb 154 b 3f 155ENDPROC(vector_bhb_loop8_swi) 156 157 .align 5 158ENTRY(vector_bhb_bpiall_swi) 159 sub sp, sp, #PT_REGS_SIZE 160 stmia sp, {r0 - r12} 161 mcr p15, 0, r8, c7, c5, 6 @ BPIALL 162 isb 163 b 3f 164ENDPROC(vector_bhb_bpiall_swi) 165#endif 166 .align 5 167ENTRY(vector_swi) 168#ifdef CONFIG_CPU_V7M 169 v7m_exception_entry 170#else 171 sub sp, sp, #PT_REGS_SIZE 172 stmia sp, {r0 - r12} @ Calling r0 - r12 1733: 174 ARM( add r8, sp, #S_PC ) 175 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 176 THUMB( mov r8, sp ) 177 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 178 mrs saved_psr, spsr @ called from non-FIQ mode, so ok. 179 TRACE( mov saved_pc, lr ) 180 str saved_pc, [sp, #S_PC] @ Save calling PC 181 str saved_psr, [sp, #S_PSR] @ Save CPSR 182 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 183#endif 184 reload_current r10, ip 185 zero_fp 186 alignment_trap r10, ip, cr_alignment 187 asm_trace_hardirqs_on save=0 188 enable_irq_notrace 189 ct_user_exit save=0 190 191 /* 192 * Get the system call number. 193 */ 194 195#if defined(CONFIG_OABI_COMPAT) 196 197 /* 198 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 199 * value to determine if it is an EABI or an old ABI call. 200 */ 201#ifdef CONFIG_ARM_THUMB 202 tst saved_psr, #PSR_T_BIT 203 movne r10, #0 @ no thumb OABI emulation 204 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction 205#else 206 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction 207#endif 208 ARM_BE8(rev r10, r10) @ little endian instruction 209 210#elif defined(CONFIG_AEABI) 211 212 /* 213 * Pure EABI user space always put syscall number into scno (r7). 214 */ 215#elif defined(CONFIG_ARM_THUMB) 216 /* Legacy ABI only, possibly thumb mode. */ 217 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs 218 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 219 USER( ldreq scno, [saved_pc, #-4] ) 220 221#else 222 /* Legacy ABI only. */ 223 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction 224#endif 225 226 /* saved_psr and saved_pc are now dead */ 227 228 uaccess_disable tbl 229 get_thread_info tsk 230 231 adr tbl, sys_call_table @ load syscall table pointer 232 233#if defined(CONFIG_OABI_COMPAT) 234 /* 235 * If the swi argument is zero, this is an EABI call and we do nothing. 236 * 237 * If this is an old ABI call, get the syscall number into scno and 238 * get the old ABI syscall table address. 239 */ 240 bics r10, r10, #0xff000000 241 strne r10, [tsk, #TI_ABI_SYSCALL] 242 streq scno, [tsk, #TI_ABI_SYSCALL] 243 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 244 ldrne tbl, =sys_oabi_call_table 245#elif !defined(CONFIG_AEABI) 246 bic scno, scno, #0xff000000 @ mask off SWI op-code 247 str scno, [tsk, #TI_ABI_SYSCALL] 248 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 249#else 250 str scno, [tsk, #TI_ABI_SYSCALL] 251#endif 252 /* 253 * Reload the registers that may have been corrupted on entry to 254 * the syscall assembly (by tracing or context tracking.) 255 */ 256 TRACE( ldmia sp, {r0 - r3} ) 257 258local_restart: 259 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 260 stmdb sp!, {r4, r5} @ push fifth and sixth args 261 262 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 263 bne __sys_trace 264 265 invoke_syscall tbl, scno, r10, __ret_fast_syscall 266 267 add r1, sp, #S_OFF 2682: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 269 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 270 bcs arm_syscall 271 mov why, #0 @ no longer a real syscall 272 b sys_ni_syscall @ not private func 273 274#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 275 /* 276 * We failed to handle a fault trying to access the page 277 * containing the swi instruction, but we're not really in a 278 * position to return -EFAULT. Instead, return back to the 279 * instruction and re-enter the user fault handling path trying 280 * to page it in. This will likely result in sending SEGV to the 281 * current task. 282 */ 2839001: 284 sub lr, saved_pc, #4 285 str lr, [sp, #S_PC] 286 get_thread_info tsk 287 b ret_fast_syscall 288#endif 289ENDPROC(vector_swi) 290 .ltorg 291 292 /* 293 * This is the really slow path. We're going to be doing 294 * context switches, and waiting for our parent to respond. 295 */ 296__sys_trace: 297 add r0, sp, #S_OFF 298 bl syscall_trace_enter 299 mov scno, r0 300 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1 301 cmp scno, #-1 @ skip the syscall? 302 bne 2b 303 add sp, sp, #S_OFF @ restore stack 304 305__sys_trace_return_nosave: 306 enable_irq_notrace 307 mov r0, sp 308 bl syscall_trace_exit 309 b ret_slow_syscall 310 311__sys_trace_return: 312 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 313 mov r0, sp 314 bl syscall_trace_exit 315 b ret_slow_syscall 316 317 .macro syscall_table_start, sym 318 .equ __sys_nr, 0 319 .type \sym, #object 320ENTRY(\sym) 321 .endm 322 323 .macro syscall, nr, func 324 .ifgt __sys_nr - \nr 325 .error "Duplicated/unorded system call entry" 326 .endif 327 .rept \nr - __sys_nr 328 .long sys_ni_syscall 329 .endr 330 .long \func 331 .equ __sys_nr, \nr + 1 332 .endm 333 334 .macro syscall_table_end, sym 335 .ifgt __sys_nr - __NR_syscalls 336 .error "System call table too big" 337 .endif 338 .rept __NR_syscalls - __sys_nr 339 .long sys_ni_syscall 340 .endr 341 .size \sym, . - \sym 342 .endm 343 344#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native) 345#define __SYSCALL(nr, func) syscall nr, func 346 347/* 348 * This is the syscall table declaration for native ABI syscalls. 349 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 350 */ 351 syscall_table_start sys_call_table 352#ifdef CONFIG_AEABI 353#include <calls-eabi.S> 354#else 355#include <calls-oabi.S> 356#endif 357 syscall_table_end sys_call_table 358 359/*============================================================================ 360 * Special system call wrappers 361 */ 362@ r0 = syscall number 363@ r8 = syscall table 364sys_syscall: 365 bic scno, r0, #__NR_OABI_SYSCALL_BASE 366 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 367 cmpne scno, #NR_syscalls @ check range 368#ifdef CONFIG_CPU_SPECTRE 369 movhs scno, #0 370 csdb 371#endif 372 stmialo sp, {r5, r6} @ shuffle args 373 movlo r0, r1 374 movlo r1, r2 375 movlo r2, r3 376 movlo r3, r4 377 ldrlo pc, [tbl, scno, lsl #2] 378 b sys_ni_syscall 379ENDPROC(sys_syscall) 380 381sys_sigreturn_wrapper: 382 add r0, sp, #S_OFF 383 mov why, #0 @ prevent syscall restart handling 384 b sys_sigreturn 385ENDPROC(sys_sigreturn_wrapper) 386 387sys_rt_sigreturn_wrapper: 388 add r0, sp, #S_OFF 389 mov why, #0 @ prevent syscall restart handling 390 b sys_rt_sigreturn 391ENDPROC(sys_rt_sigreturn_wrapper) 392 393sys_statfs64_wrapper: 394 teq r1, #88 395 moveq r1, #84 396 b sys_statfs64 397ENDPROC(sys_statfs64_wrapper) 398 399sys_fstatfs64_wrapper: 400 teq r1, #88 401 moveq r1, #84 402 b sys_fstatfs64 403ENDPROC(sys_fstatfs64_wrapper) 404 405/* 406 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 407 * offset, we return EINVAL. 408 */ 409sys_mmap2: 410 str r5, [sp, #4] 411 b sys_mmap_pgoff 412ENDPROC(sys_mmap2) 413 414#ifdef CONFIG_OABI_COMPAT 415 416/* 417 * These are syscalls with argument register differences 418 */ 419 420sys_oabi_pread64: 421 stmia sp, {r3, r4} 422 b sys_pread64 423ENDPROC(sys_oabi_pread64) 424 425sys_oabi_pwrite64: 426 stmia sp, {r3, r4} 427 b sys_pwrite64 428ENDPROC(sys_oabi_pwrite64) 429 430sys_oabi_truncate64: 431 mov r3, r2 432 mov r2, r1 433 b sys_truncate64 434ENDPROC(sys_oabi_truncate64) 435 436sys_oabi_ftruncate64: 437 mov r3, r2 438 mov r2, r1 439 b sys_ftruncate64 440ENDPROC(sys_oabi_ftruncate64) 441 442sys_oabi_readahead: 443 str r3, [sp] 444 mov r3, r2 445 mov r2, r1 446 b sys_readahead 447ENDPROC(sys_oabi_readahead) 448 449/* 450 * Let's declare a second syscall table for old ABI binaries 451 * using the compatibility syscall entries. 452 */ 453 syscall_table_start sys_oabi_call_table 454#undef __SYSCALL_WITH_COMPAT 455#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat) 456#include <calls-oabi.S> 457 syscall_table_end sys_oabi_call_table 458 459#endif 460 461