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/page.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 str scno, [tsk, #TI_ABI_SYSCALL] @ make sure tracers see update 94 ldmia sp, {r0 - r6} @ have to reload r0 - r6 95 b local_restart @ ... and off we go 96ENDPROC(ret_fast_syscall) 97 98/* 99 * "slow" syscall return path. "why" tells us if this was a real syscall. 100 * IRQs may be enabled here, so always disable them. Note that we use the 101 * "notrace" version to avoid calling into the tracing code unnecessarily. 102 * do_work_pending() will update this state if necessary. 103 */ 104ENTRY(ret_to_user) 105ret_slow_syscall: 106#if IS_ENABLED(CONFIG_DEBUG_RSEQ) 107 /* do_rseq_syscall needs interrupts enabled. */ 108 enable_irq_notrace @ enable interrupts 109 mov r0, sp @ 'regs' 110 bl do_rseq_syscall 111#endif 112 disable_irq_notrace @ disable interrupts 113ENTRY(ret_to_user_from_irq) 114 ldr r1, [tsk, #TI_FLAGS] 115 movs r1, r1, lsl #16 116 bne slow_work_pending 117no_work_pending: 118 asm_trace_hardirqs_on save = 0 119 120 ct_user_enter save = 0 121 122#ifdef CONFIG_GCC_PLUGIN_STACKLEAK 123 bl stackleak_erase_on_task_stack 124#endif 125 restore_user_regs fast = 0, offset = 0 126ENDPROC(ret_to_user_from_irq) 127ENDPROC(ret_to_user) 128 129/* 130 * This is how we return from a fork. 131 */ 132ENTRY(ret_from_fork) 133 bl schedule_tail 134 cmp r5, #0 135 movne r0, r4 136 badrne lr, 1f 137 retne r5 1381: get_thread_info tsk 139 b ret_slow_syscall 140ENDPROC(ret_from_fork) 141 142/*============================================================================= 143 * SWI handler 144 *----------------------------------------------------------------------------- 145 */ 146 147 .align 5 148#ifdef CONFIG_HARDEN_BRANCH_HISTORY 149ENTRY(vector_bhb_loop8_swi) 150 sub sp, sp, #PT_REGS_SIZE 151 stmia sp, {r0 - r12} 152 mov r8, #8 1531: b 2f 1542: subs r8, r8, #1 155 bne 1b 156 dsb nsh 157 isb 158 b 3f 159ENDPROC(vector_bhb_loop8_swi) 160 161 .align 5 162ENTRY(vector_bhb_bpiall_swi) 163 sub sp, sp, #PT_REGS_SIZE 164 stmia sp, {r0 - r12} 165 mcr p15, 0, r8, c7, c5, 6 @ BPIALL 166 isb 167 b 3f 168ENDPROC(vector_bhb_bpiall_swi) 169#endif 170 .align 5 171ENTRY(vector_swi) 172#ifdef CONFIG_CPU_V7M 173 v7m_exception_entry 174#else 175 sub sp, sp, #PT_REGS_SIZE 176 stmia sp, {r0 - r12} @ Calling r0 - r12 1773: 178 ARM( add r8, sp, #S_PC ) 179 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 180 THUMB( mov r8, sp ) 181 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 182 mrs saved_psr, spsr @ called from non-FIQ mode, so ok. 183 TRACE( mov saved_pc, lr ) 184 str saved_pc, [sp, #S_PC] @ Save calling PC 185 str saved_psr, [sp, #S_PSR] @ Save CPSR 186 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 187#endif 188 reload_current r10, ip 189 zero_fp 190 alignment_trap r10, ip, cr_alignment 191 asm_trace_hardirqs_on save=0 192 enable_irq_notrace 193 ct_user_exit save=0 194 195 /* 196 * Get the system call number. 197 */ 198 199#if defined(CONFIG_OABI_COMPAT) 200 201 /* 202 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 203 * value to determine if it is an EABI or an old ABI call. 204 */ 205#ifdef CONFIG_ARM_THUMB 206 tst saved_psr, #PSR_T_BIT 207 movne r10, #0 @ no thumb OABI emulation 208 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction 209#else 210 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction 211#endif 212 ARM_BE8(rev r10, r10) @ little endian instruction 213 214#elif defined(CONFIG_AEABI) 215 216 /* 217 * Pure EABI user space always put syscall number into scno (r7). 218 */ 219#elif defined(CONFIG_ARM_THUMB) 220 /* Legacy ABI only, possibly thumb mode. */ 221 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs 222 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 223 USER( ldreq scno, [saved_pc, #-4] ) 224 225#else 226 /* Legacy ABI only. */ 227 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction 228#endif 229 230 /* saved_psr and saved_pc are now dead */ 231 232 uaccess_disable tbl 233 get_thread_info tsk 234 235 adr tbl, sys_call_table @ load syscall table pointer 236 237#if defined(CONFIG_OABI_COMPAT) 238 /* 239 * If the swi argument is zero, this is an EABI call and we do nothing. 240 * 241 * If this is an old ABI call, get the syscall number into scno and 242 * get the old ABI syscall table address. 243 */ 244 bics r10, r10, #0xff000000 245 strne r10, [tsk, #TI_ABI_SYSCALL] 246 streq scno, [tsk, #TI_ABI_SYSCALL] 247 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 248 ldrne tbl, =sys_oabi_call_table 249#elif !defined(CONFIG_AEABI) 250 bic scno, scno, #0xff000000 @ mask off SWI op-code 251 str scno, [tsk, #TI_ABI_SYSCALL] 252 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 253#else 254 str scno, [tsk, #TI_ABI_SYSCALL] 255#endif 256 /* 257 * Reload the registers that may have been corrupted on entry to 258 * the syscall assembly (by tracing or context tracking.) 259 */ 260 TRACE( ldmia sp, {r0 - r3} ) 261 262local_restart: 263 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 264 stmdb sp!, {r4, r5} @ push fifth and sixth args 265 266 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 267 bne __sys_trace 268 269 invoke_syscall tbl, scno, r10, __ret_fast_syscall 270 271 add r1, sp, #S_OFF 2722: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 273 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 274 bcs arm_syscall 275 mov why, #0 @ no longer a real syscall 276 b sys_ni_syscall @ not private func 277 278#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 279 /* 280 * We failed to handle a fault trying to access the page 281 * containing the swi instruction, but we're not really in a 282 * position to return -EFAULT. Instead, return back to the 283 * instruction and re-enter the user fault handling path trying 284 * to page it in. This will likely result in sending SEGV to the 285 * current task. 286 */ 2879001: 288 sub lr, saved_pc, #4 289 str lr, [sp, #S_PC] 290 get_thread_info tsk 291 b ret_fast_syscall 292#endif 293ENDPROC(vector_swi) 294 .ltorg 295 296 /* 297 * This is the really slow path. We're going to be doing 298 * context switches, and waiting for our parent to respond. 299 */ 300__sys_trace: 301 add r0, sp, #S_OFF 302 bl syscall_trace_enter 303 mov scno, r0 304 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1 305 cmp scno, #-1 @ skip the syscall? 306 bne 2b 307 add sp, sp, #S_OFF @ restore stack 308 309__sys_trace_return_nosave: 310 enable_irq_notrace 311 mov r0, sp 312 bl syscall_trace_exit 313 b ret_slow_syscall 314 315__sys_trace_return: 316 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 317 mov r0, sp 318 bl syscall_trace_exit 319 b ret_slow_syscall 320 321 .macro syscall_table_start, sym 322 .equ __sys_nr, 0 323 .type \sym, #object 324ENTRY(\sym) 325 .endm 326 327 .macro syscall, nr, func 328 .ifgt __sys_nr - \nr 329 .error "Duplicated/unorded system call entry" 330 .endif 331 .rept \nr - __sys_nr 332 .long sys_ni_syscall 333 .endr 334 .long \func 335 .equ __sys_nr, \nr + 1 336 .endm 337 338 .macro syscall_table_end, sym 339 .ifgt __sys_nr - __NR_syscalls 340 .error "System call table too big" 341 .endif 342 .rept __NR_syscalls - __sys_nr 343 .long sys_ni_syscall 344 .endr 345 .size \sym, . - \sym 346 .endm 347 348#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native) 349#define __SYSCALL(nr, func) syscall nr, func 350 351/* 352 * This is the syscall table declaration for native ABI syscalls. 353 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 354 */ 355 syscall_table_start sys_call_table 356#ifdef CONFIG_AEABI 357#include <calls-eabi.S> 358#else 359#include <calls-oabi.S> 360#endif 361 syscall_table_end sys_call_table 362 363/*============================================================================ 364 * Special system call wrappers 365 */ 366@ r0 = syscall number 367@ r8 = syscall table 368sys_syscall: 369 bic scno, r0, #__NR_OABI_SYSCALL_BASE 370 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 371 cmpne scno, #NR_syscalls @ check range 372#ifdef CONFIG_CPU_SPECTRE 373 movhs scno, #0 374 csdb 375#endif 376 stmialo sp, {r5, r6} @ shuffle args 377 movlo r0, r1 378 movlo r1, r2 379 movlo r2, r3 380 movlo r3, r4 381 ldrlo pc, [tbl, scno, lsl #2] 382 b sys_ni_syscall 383ENDPROC(sys_syscall) 384 385sys_sigreturn_wrapper: 386 add r0, sp, #S_OFF 387 mov why, #0 @ prevent syscall restart handling 388 b sys_sigreturn 389ENDPROC(sys_sigreturn_wrapper) 390 391sys_rt_sigreturn_wrapper: 392 add r0, sp, #S_OFF 393 mov why, #0 @ prevent syscall restart handling 394 b sys_rt_sigreturn 395ENDPROC(sys_rt_sigreturn_wrapper) 396 397sys_statfs64_wrapper: 398 teq r1, #88 399 moveq r1, #84 400 b sys_statfs64 401ENDPROC(sys_statfs64_wrapper) 402 403sys_fstatfs64_wrapper: 404 teq r1, #88 405 moveq r1, #84 406 b sys_fstatfs64 407ENDPROC(sys_fstatfs64_wrapper) 408 409/* 410 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 411 * offset, we return EINVAL. 412 */ 413sys_mmap2: 414 str r5, [sp, #4] 415 b sys_mmap_pgoff 416ENDPROC(sys_mmap2) 417 418#ifdef CONFIG_OABI_COMPAT 419 420/* 421 * These are syscalls with argument register differences 422 */ 423 424sys_oabi_pread64: 425 stmia sp, {r3, r4} 426 b sys_pread64 427ENDPROC(sys_oabi_pread64) 428 429sys_oabi_pwrite64: 430 stmia sp, {r3, r4} 431 b sys_pwrite64 432ENDPROC(sys_oabi_pwrite64) 433 434sys_oabi_truncate64: 435 mov r3, r2 436 mov r2, r1 437 b sys_truncate64 438ENDPROC(sys_oabi_truncate64) 439 440sys_oabi_ftruncate64: 441 mov r3, r2 442 mov r2, r1 443 b sys_ftruncate64 444ENDPROC(sys_oabi_ftruncate64) 445 446sys_oabi_readahead: 447 str r3, [sp] 448 mov r3, r2 449 mov r2, r1 450 b sys_readahead 451ENDPROC(sys_oabi_readahead) 452 453/* 454 * Let's declare a second syscall table for old ABI binaries 455 * using the compatibility syscall entries. 456 */ 457 syscall_table_start sys_oabi_call_table 458#undef __SYSCALL_WITH_COMPAT 459#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat) 460#include <calls-oabi.S> 461 syscall_table_end sys_oabi_call_table 462 463#endif 464 465