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 restore_user_regs fast = 0, offset = 0 123ENDPROC(ret_to_user_from_irq) 124ENDPROC(ret_to_user) 125 126/* 127 * This is how we return from a fork. 128 */ 129ENTRY(ret_from_fork) 130 bl schedule_tail 131 cmp r5, #0 132 movne r0, r4 133 badrne lr, 1f 134 retne r5 1351: get_thread_info tsk 136 b ret_slow_syscall 137ENDPROC(ret_from_fork) 138 139/*============================================================================= 140 * SWI handler 141 *----------------------------------------------------------------------------- 142 */ 143 144 .align 5 145#ifdef CONFIG_HARDEN_BRANCH_HISTORY 146ENTRY(vector_bhb_loop8_swi) 147 sub sp, sp, #PT_REGS_SIZE 148 stmia sp, {r0 - r12} 149 mov r8, #8 1501: b 2f 1512: subs r8, r8, #1 152 bne 1b 153 dsb nsh 154 isb 155 b 3f 156ENDPROC(vector_bhb_loop8_swi) 157 158 .align 5 159ENTRY(vector_bhb_bpiall_swi) 160 sub sp, sp, #PT_REGS_SIZE 161 stmia sp, {r0 - r12} 162 mcr p15, 0, r8, c7, c5, 6 @ BPIALL 163 isb 164 b 3f 165ENDPROC(vector_bhb_bpiall_swi) 166#endif 167 .align 5 168ENTRY(vector_swi) 169#ifdef CONFIG_CPU_V7M 170 v7m_exception_entry 171#else 172 sub sp, sp, #PT_REGS_SIZE 173 stmia sp, {r0 - r12} @ Calling r0 - r12 1743: 175 ARM( add r8, sp, #S_PC ) 176 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 177 THUMB( mov r8, sp ) 178 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 179 mrs saved_psr, spsr @ called from non-FIQ mode, so ok. 180 TRACE( mov saved_pc, lr ) 181 str saved_pc, [sp, #S_PC] @ Save calling PC 182 str saved_psr, [sp, #S_PSR] @ Save CPSR 183 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 184#endif 185 reload_current r10, ip 186 zero_fp 187 alignment_trap r10, ip, cr_alignment 188 asm_trace_hardirqs_on save=0 189 enable_irq_notrace 190 ct_user_exit save=0 191 192 /* 193 * Get the system call number. 194 */ 195 196#if defined(CONFIG_OABI_COMPAT) 197 198 /* 199 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 200 * value to determine if it is an EABI or an old ABI call. 201 */ 202#ifdef CONFIG_ARM_THUMB 203 tst saved_psr, #PSR_T_BIT 204 movne r10, #0 @ no thumb OABI emulation 205 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction 206#else 207 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction 208#endif 209 ARM_BE8(rev r10, r10) @ little endian instruction 210 211#elif defined(CONFIG_AEABI) 212 213 /* 214 * Pure EABI user space always put syscall number into scno (r7). 215 */ 216#elif defined(CONFIG_ARM_THUMB) 217 /* Legacy ABI only, possibly thumb mode. */ 218 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs 219 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 220 USER( ldreq scno, [saved_pc, #-4] ) 221 222#else 223 /* Legacy ABI only. */ 224 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction 225#endif 226 227 /* saved_psr and saved_pc are now dead */ 228 229 uaccess_disable tbl 230 get_thread_info tsk 231 232 adr tbl, sys_call_table @ load syscall table pointer 233 234#if defined(CONFIG_OABI_COMPAT) 235 /* 236 * If the swi argument is zero, this is an EABI call and we do nothing. 237 * 238 * If this is an old ABI call, get the syscall number into scno and 239 * get the old ABI syscall table address. 240 */ 241 bics r10, r10, #0xff000000 242 strne r10, [tsk, #TI_ABI_SYSCALL] 243 streq scno, [tsk, #TI_ABI_SYSCALL] 244 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 245 ldrne tbl, =sys_oabi_call_table 246#elif !defined(CONFIG_AEABI) 247 bic scno, scno, #0xff000000 @ mask off SWI op-code 248 str scno, [tsk, #TI_ABI_SYSCALL] 249 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 250#else 251 str scno, [tsk, #TI_ABI_SYSCALL] 252#endif 253 /* 254 * Reload the registers that may have been corrupted on entry to 255 * the syscall assembly (by tracing or context tracking.) 256 */ 257 TRACE( ldmia sp, {r0 - r3} ) 258 259local_restart: 260 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 261 stmdb sp!, {r4, r5} @ push fifth and sixth args 262 263 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 264 bne __sys_trace 265 266 invoke_syscall tbl, scno, r10, __ret_fast_syscall 267 268 add r1, sp, #S_OFF 2692: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 270 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 271 bcs arm_syscall 272 mov why, #0 @ no longer a real syscall 273 b sys_ni_syscall @ not private func 274 275#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 276 /* 277 * We failed to handle a fault trying to access the page 278 * containing the swi instruction, but we're not really in a 279 * position to return -EFAULT. Instead, return back to the 280 * instruction and re-enter the user fault handling path trying 281 * to page it in. This will likely result in sending SEGV to the 282 * current task. 283 */ 2849001: 285 sub lr, saved_pc, #4 286 str lr, [sp, #S_PC] 287 get_thread_info tsk 288 b ret_fast_syscall 289#endif 290ENDPROC(vector_swi) 291 .ltorg 292 293 /* 294 * This is the really slow path. We're going to be doing 295 * context switches, and waiting for our parent to respond. 296 */ 297__sys_trace: 298 add r0, sp, #S_OFF 299 bl syscall_trace_enter 300 mov scno, r0 301 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1 302 cmp scno, #-1 @ skip the syscall? 303 bne 2b 304 add sp, sp, #S_OFF @ restore stack 305 306__sys_trace_return_nosave: 307 enable_irq_notrace 308 mov r0, sp 309 bl syscall_trace_exit 310 b ret_slow_syscall 311 312__sys_trace_return: 313 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 314 mov r0, sp 315 bl syscall_trace_exit 316 b ret_slow_syscall 317 318 .macro syscall_table_start, sym 319 .equ __sys_nr, 0 320 .type \sym, #object 321ENTRY(\sym) 322 .endm 323 324 .macro syscall, nr, func 325 .ifgt __sys_nr - \nr 326 .error "Duplicated/unorded system call entry" 327 .endif 328 .rept \nr - __sys_nr 329 .long sys_ni_syscall 330 .endr 331 .long \func 332 .equ __sys_nr, \nr + 1 333 .endm 334 335 .macro syscall_table_end, sym 336 .ifgt __sys_nr - __NR_syscalls 337 .error "System call table too big" 338 .endif 339 .rept __NR_syscalls - __sys_nr 340 .long sys_ni_syscall 341 .endr 342 .size \sym, . - \sym 343 .endm 344 345#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native) 346#define __SYSCALL(nr, func) syscall nr, func 347 348/* 349 * This is the syscall table declaration for native ABI syscalls. 350 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 351 */ 352 syscall_table_start sys_call_table 353#ifdef CONFIG_AEABI 354#include <calls-eabi.S> 355#else 356#include <calls-oabi.S> 357#endif 358 syscall_table_end sys_call_table 359 360/*============================================================================ 361 * Special system call wrappers 362 */ 363@ r0 = syscall number 364@ r8 = syscall table 365sys_syscall: 366 bic scno, r0, #__NR_OABI_SYSCALL_BASE 367 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 368 cmpne scno, #NR_syscalls @ check range 369#ifdef CONFIG_CPU_SPECTRE 370 movhs scno, #0 371 csdb 372#endif 373 stmialo sp, {r5, r6} @ shuffle args 374 movlo r0, r1 375 movlo r1, r2 376 movlo r2, r3 377 movlo r3, r4 378 ldrlo pc, [tbl, scno, lsl #2] 379 b sys_ni_syscall 380ENDPROC(sys_syscall) 381 382sys_sigreturn_wrapper: 383 add r0, sp, #S_OFF 384 mov why, #0 @ prevent syscall restart handling 385 b sys_sigreturn 386ENDPROC(sys_sigreturn_wrapper) 387 388sys_rt_sigreturn_wrapper: 389 add r0, sp, #S_OFF 390 mov why, #0 @ prevent syscall restart handling 391 b sys_rt_sigreturn 392ENDPROC(sys_rt_sigreturn_wrapper) 393 394sys_statfs64_wrapper: 395 teq r1, #88 396 moveq r1, #84 397 b sys_statfs64 398ENDPROC(sys_statfs64_wrapper) 399 400sys_fstatfs64_wrapper: 401 teq r1, #88 402 moveq r1, #84 403 b sys_fstatfs64 404ENDPROC(sys_fstatfs64_wrapper) 405 406/* 407 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 408 * offset, we return EINVAL. 409 */ 410sys_mmap2: 411 str r5, [sp, #4] 412 b sys_mmap_pgoff 413ENDPROC(sys_mmap2) 414 415#ifdef CONFIG_OABI_COMPAT 416 417/* 418 * These are syscalls with argument register differences 419 */ 420 421sys_oabi_pread64: 422 stmia sp, {r3, r4} 423 b sys_pread64 424ENDPROC(sys_oabi_pread64) 425 426sys_oabi_pwrite64: 427 stmia sp, {r3, r4} 428 b sys_pwrite64 429ENDPROC(sys_oabi_pwrite64) 430 431sys_oabi_truncate64: 432 mov r3, r2 433 mov r2, r1 434 b sys_truncate64 435ENDPROC(sys_oabi_truncate64) 436 437sys_oabi_ftruncate64: 438 mov r3, r2 439 mov r2, r1 440 b sys_ftruncate64 441ENDPROC(sys_oabi_ftruncate64) 442 443sys_oabi_readahead: 444 str r3, [sp] 445 mov r3, r2 446 mov r2, r1 447 b sys_readahead 448ENDPROC(sys_oabi_readahead) 449 450/* 451 * Let's declare a second syscall table for old ABI binaries 452 * using the compatibility syscall entries. 453 */ 454 syscall_table_start sys_oabi_call_table 455#undef __SYSCALL_WITH_COMPAT 456#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat) 457#include <calls-oabi.S> 458 syscall_table_end sys_oabi_call_table 459 460#endif 461 462