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 .macro arch_ret_to_user, tmp 20#ifdef CONFIG_ARCH_IOP32X 21 mrc p15, 0, \tmp, c15, c1, 0 22 tst \tmp, #(1 << 6) 23 bicne \tmp, \tmp, #(1 << 6) 24 mcrne p15, 0, \tmp, c15, c1, 0 @ Disable cp6 access 25#endif 26 .endm 27 28#include "entry-header.S" 29 30saved_psr .req r8 31#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING) 32saved_pc .req r9 33#define TRACE(x...) x 34#else 35saved_pc .req lr 36#define TRACE(x...) 37#endif 38 39 .section .entry.text,"ax",%progbits 40 .align 5 41#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING) || \ 42 IS_ENABLED(CONFIG_DEBUG_RSEQ)) 43/* 44 * This is the fast syscall return path. We do as little as possible here, 45 * such as avoiding writing r0 to the stack. We only use this path if we 46 * have tracing, context tracking and rseq debug disabled - the overheads 47 * from those features make this path too inefficient. 48 */ 49ret_fast_syscall: 50__ret_fast_syscall: 51 UNWIND(.fnstart ) 52 UNWIND(.cantunwind ) 53 disable_irq_notrace @ disable interrupts 54 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 55 movs r1, r1, lsl #16 56 bne fast_work_pending 57 58 59 /* perform architecture specific actions before user return */ 60 arch_ret_to_user r1 61 62 restore_user_regs fast = 1, offset = S_OFF 63 UNWIND(.fnend ) 64ENDPROC(ret_fast_syscall) 65 66 /* Ok, we need to do extra processing, enter the slow path. */ 67fast_work_pending: 68 str r0, [sp, #S_R0+S_OFF]! @ returned r0 69 /* fall through to work_pending */ 70#else 71/* 72 * The "replacement" ret_fast_syscall for when tracing, context tracking, 73 * or rseq debug is enabled. As we will need to call out to some C functions, 74 * we save r0 first to avoid needing to save registers around each C function 75 * call. 76 */ 77ret_fast_syscall: 78__ret_fast_syscall: 79 UNWIND(.fnstart ) 80 UNWIND(.cantunwind ) 81 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 82#if IS_ENABLED(CONFIG_DEBUG_RSEQ) 83 /* do_rseq_syscall needs interrupts enabled. */ 84 mov r0, sp @ 'regs' 85 bl do_rseq_syscall 86#endif 87 disable_irq_notrace @ disable interrupts 88 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 89 movs r1, r1, lsl #16 90 beq no_work_pending 91 UNWIND(.fnend ) 92ENDPROC(ret_fast_syscall) 93 94 /* Slower path - fall through to work_pending */ 95#endif 96 97 tst r1, #_TIF_SYSCALL_WORK 98 bne __sys_trace_return_nosave 99slow_work_pending: 100 mov r0, sp @ 'regs' 101 mov r2, why @ 'syscall' 102 bl do_work_pending 103 cmp r0, #0 104 beq no_work_pending 105 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) 106 ldmia sp, {r0 - r6} @ have to reload r0 - r6 107 b local_restart @ ... and off we go 108ENDPROC(ret_fast_syscall) 109 110/* 111 * "slow" syscall return path. "why" tells us if this was a real syscall. 112 * IRQs may be enabled here, so always disable them. Note that we use the 113 * "notrace" version to avoid calling into the tracing code unnecessarily. 114 * do_work_pending() will update this state if necessary. 115 */ 116ENTRY(ret_to_user) 117ret_slow_syscall: 118#if IS_ENABLED(CONFIG_DEBUG_RSEQ) 119 /* do_rseq_syscall needs interrupts enabled. */ 120 enable_irq_notrace @ enable interrupts 121 mov r0, sp @ 'regs' 122 bl do_rseq_syscall 123#endif 124 disable_irq_notrace @ disable interrupts 125ENTRY(ret_to_user_from_irq) 126 ldr r1, [tsk, #TI_FLAGS] 127 movs r1, r1, lsl #16 128 bne slow_work_pending 129no_work_pending: 130 asm_trace_hardirqs_on save = 0 131 132 /* perform architecture specific actions before user return */ 133 arch_ret_to_user r1 134 ct_user_enter save = 0 135 136 restore_user_regs fast = 0, offset = 0 137ENDPROC(ret_to_user_from_irq) 138ENDPROC(ret_to_user) 139 140/* 141 * This is how we return from a fork. 142 */ 143ENTRY(ret_from_fork) 144 bl schedule_tail 145 cmp r5, #0 146 movne r0, r4 147 badrne lr, 1f 148 retne r5 1491: get_thread_info tsk 150 b ret_slow_syscall 151ENDPROC(ret_from_fork) 152 153/*============================================================================= 154 * SWI handler 155 *----------------------------------------------------------------------------- 156 */ 157 158 .align 5 159#ifdef CONFIG_HARDEN_BRANCH_HISTORY 160ENTRY(vector_bhb_loop8_swi) 161 sub sp, sp, #PT_REGS_SIZE 162 stmia sp, {r0 - r12} 163 mov r8, #8 1641: b 2f 1652: subs r8, r8, #1 166 bne 1b 167 dsb nsh 168 isb 169 b 3f 170ENDPROC(vector_bhb_loop8_swi) 171 172 .align 5 173ENTRY(vector_bhb_bpiall_swi) 174 sub sp, sp, #PT_REGS_SIZE 175 stmia sp, {r0 - r12} 176 mcr p15, 0, r8, c7, c5, 6 @ BPIALL 177 isb 178 b 3f 179ENDPROC(vector_bhb_bpiall_swi) 180#endif 181 .align 5 182ENTRY(vector_swi) 183#ifdef CONFIG_CPU_V7M 184 v7m_exception_entry 185#else 186 sub sp, sp, #PT_REGS_SIZE 187 stmia sp, {r0 - r12} @ Calling r0 - r12 1883: 189 ARM( add r8, sp, #S_PC ) 190 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 191 THUMB( mov r8, sp ) 192 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 193 mrs saved_psr, spsr @ called from non-FIQ mode, so ok. 194 TRACE( mov saved_pc, lr ) 195 str saved_pc, [sp, #S_PC] @ Save calling PC 196 str saved_psr, [sp, #S_PSR] @ Save CPSR 197 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 198#endif 199 reload_current r10, ip 200 zero_fp 201 alignment_trap r10, ip, cr_alignment 202 asm_trace_hardirqs_on save=0 203 enable_irq_notrace 204 ct_user_exit save=0 205 206 /* 207 * Get the system call number. 208 */ 209 210#if defined(CONFIG_OABI_COMPAT) 211 212 /* 213 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 214 * value to determine if it is an EABI or an old ABI call. 215 */ 216#ifdef CONFIG_ARM_THUMB 217 tst saved_psr, #PSR_T_BIT 218 movne r10, #0 @ no thumb OABI emulation 219 USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction 220#else 221 USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction 222#endif 223 ARM_BE8(rev r10, r10) @ little endian instruction 224 225#elif defined(CONFIG_AEABI) 226 227 /* 228 * Pure EABI user space always put syscall number into scno (r7). 229 */ 230#elif defined(CONFIG_ARM_THUMB) 231 /* Legacy ABI only, possibly thumb mode. */ 232 tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs 233 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 234 USER( ldreq scno, [saved_pc, #-4] ) 235 236#else 237 /* Legacy ABI only. */ 238 USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction 239#endif 240 241 /* saved_psr and saved_pc are now dead */ 242 243 uaccess_disable tbl 244 get_thread_info tsk 245 246 adr tbl, sys_call_table @ load syscall table pointer 247 248#if defined(CONFIG_OABI_COMPAT) 249 /* 250 * If the swi argument is zero, this is an EABI call and we do nothing. 251 * 252 * If this is an old ABI call, get the syscall number into scno and 253 * get the old ABI syscall table address. 254 */ 255 bics r10, r10, #0xff000000 256 strne r10, [tsk, #TI_ABI_SYSCALL] 257 streq scno, [tsk, #TI_ABI_SYSCALL] 258 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 259 ldrne tbl, =sys_oabi_call_table 260#elif !defined(CONFIG_AEABI) 261 bic scno, scno, #0xff000000 @ mask off SWI op-code 262 str scno, [tsk, #TI_ABI_SYSCALL] 263 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 264#else 265 str scno, [tsk, #TI_ABI_SYSCALL] 266#endif 267 /* 268 * Reload the registers that may have been corrupted on entry to 269 * the syscall assembly (by tracing or context tracking.) 270 */ 271 TRACE( ldmia sp, {r0 - r3} ) 272 273local_restart: 274 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 275 stmdb sp!, {r4, r5} @ push fifth and sixth args 276 277 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 278 bne __sys_trace 279 280 invoke_syscall tbl, scno, r10, __ret_fast_syscall 281 282 add r1, sp, #S_OFF 2832: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 284 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 285 bcs arm_syscall 286 mov why, #0 @ no longer a real syscall 287 b sys_ni_syscall @ not private func 288 289#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 290 /* 291 * We failed to handle a fault trying to access the page 292 * containing the swi instruction, but we're not really in a 293 * position to return -EFAULT. Instead, return back to the 294 * instruction and re-enter the user fault handling path trying 295 * to page it in. This will likely result in sending SEGV to the 296 * current task. 297 */ 2989001: 299 sub lr, saved_pc, #4 300 str lr, [sp, #S_PC] 301 get_thread_info tsk 302 b ret_fast_syscall 303#endif 304ENDPROC(vector_swi) 305 306 /* 307 * This is the really slow path. We're going to be doing 308 * context switches, and waiting for our parent to respond. 309 */ 310__sys_trace: 311 add r0, sp, #S_OFF 312 bl syscall_trace_enter 313 mov scno, r0 314 invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1 315 cmp scno, #-1 @ skip the syscall? 316 bne 2b 317 add sp, sp, #S_OFF @ restore stack 318 319__sys_trace_return_nosave: 320 enable_irq_notrace 321 mov r0, sp 322 bl syscall_trace_exit 323 b ret_slow_syscall 324 325__sys_trace_return: 326 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 327 mov r0, sp 328 bl syscall_trace_exit 329 b ret_slow_syscall 330 331 .macro syscall_table_start, sym 332 .equ __sys_nr, 0 333 .type \sym, #object 334ENTRY(\sym) 335 .endm 336 337 .macro syscall, nr, func 338 .ifgt __sys_nr - \nr 339 .error "Duplicated/unorded system call entry" 340 .endif 341 .rept \nr - __sys_nr 342 .long sys_ni_syscall 343 .endr 344 .long \func 345 .equ __sys_nr, \nr + 1 346 .endm 347 348 .macro syscall_table_end, sym 349 .ifgt __sys_nr - __NR_syscalls 350 .error "System call table too big" 351 .endif 352 .rept __NR_syscalls - __sys_nr 353 .long sys_ni_syscall 354 .endr 355 .size \sym, . - \sym 356 .endm 357 358#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native) 359#define __SYSCALL(nr, func) syscall nr, func 360 361/* 362 * This is the syscall table declaration for native ABI syscalls. 363 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 364 */ 365 syscall_table_start sys_call_table 366#ifdef CONFIG_AEABI 367#include <calls-eabi.S> 368#else 369#include <calls-oabi.S> 370#endif 371 syscall_table_end sys_call_table 372 373/*============================================================================ 374 * Special system call wrappers 375 */ 376@ r0 = syscall number 377@ r8 = syscall table 378sys_syscall: 379 bic scno, r0, #__NR_OABI_SYSCALL_BASE 380 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 381 cmpne scno, #NR_syscalls @ check range 382#ifdef CONFIG_CPU_SPECTRE 383 movhs scno, #0 384 csdb 385#endif 386 stmialo sp, {r5, r6} @ shuffle args 387 movlo r0, r1 388 movlo r1, r2 389 movlo r2, r3 390 movlo r3, r4 391 ldrlo pc, [tbl, scno, lsl #2] 392 b sys_ni_syscall 393ENDPROC(sys_syscall) 394 395sys_sigreturn_wrapper: 396 add r0, sp, #S_OFF 397 mov why, #0 @ prevent syscall restart handling 398 b sys_sigreturn 399ENDPROC(sys_sigreturn_wrapper) 400 401sys_rt_sigreturn_wrapper: 402 add r0, sp, #S_OFF 403 mov why, #0 @ prevent syscall restart handling 404 b sys_rt_sigreturn 405ENDPROC(sys_rt_sigreturn_wrapper) 406 407sys_statfs64_wrapper: 408 teq r1, #88 409 moveq r1, #84 410 b sys_statfs64 411ENDPROC(sys_statfs64_wrapper) 412 413sys_fstatfs64_wrapper: 414 teq r1, #88 415 moveq r1, #84 416 b sys_fstatfs64 417ENDPROC(sys_fstatfs64_wrapper) 418 419/* 420 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 421 * offset, we return EINVAL. 422 */ 423sys_mmap2: 424 str r5, [sp, #4] 425 b sys_mmap_pgoff 426ENDPROC(sys_mmap2) 427 428#ifdef CONFIG_OABI_COMPAT 429 430/* 431 * These are syscalls with argument register differences 432 */ 433 434sys_oabi_pread64: 435 stmia sp, {r3, r4} 436 b sys_pread64 437ENDPROC(sys_oabi_pread64) 438 439sys_oabi_pwrite64: 440 stmia sp, {r3, r4} 441 b sys_pwrite64 442ENDPROC(sys_oabi_pwrite64) 443 444sys_oabi_truncate64: 445 mov r3, r2 446 mov r2, r1 447 b sys_truncate64 448ENDPROC(sys_oabi_truncate64) 449 450sys_oabi_ftruncate64: 451 mov r3, r2 452 mov r2, r1 453 b sys_ftruncate64 454ENDPROC(sys_oabi_ftruncate64) 455 456sys_oabi_readahead: 457 str r3, [sp] 458 mov r3, r2 459 mov r2, r1 460 b sys_readahead 461ENDPROC(sys_oabi_readahead) 462 463/* 464 * Let's declare a second syscall table for old ABI binaries 465 * using the compatibility syscall entries. 466 */ 467 syscall_table_start sys_oabi_call_table 468#undef __SYSCALL_WITH_COMPAT 469#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat) 470#include <calls-oabi.S> 471 syscall_table_end sys_oabi_call_table 472 473#endif 474 475