1/* 2 * linux/arch/arm/kernel/entry-common.S 3 * 4 * Copyright (C) 2000 Russell King 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10 11#include <asm/assembler.h> 12#include <asm/unistd.h> 13#include <asm/ftrace.h> 14#include <asm/unwind.h> 15 16#ifdef CONFIG_NEED_RET_TO_USER 17#include <mach/entry-macro.S> 18#else 19 .macro arch_ret_to_user, tmp1, tmp2 20 .endm 21#endif 22 23#include "entry-header.S" 24 25 26 .align 5 27#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING)) 28/* 29 * This is the fast syscall return path. We do as little as possible here, 30 * such as avoiding writing r0 to the stack. We only use this path if we 31 * have tracing and context tracking disabled - the overheads from those 32 * features make this path too inefficient. 33 */ 34ret_fast_syscall: 35 UNWIND(.fnstart ) 36 UNWIND(.cantunwind ) 37 disable_irq_notrace @ disable interrupts 38 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 39 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK 40 bne fast_work_pending 41 42 /* perform architecture specific actions before user return */ 43 arch_ret_to_user r1, lr 44 45 restore_user_regs fast = 1, offset = S_OFF 46 UNWIND(.fnend ) 47ENDPROC(ret_fast_syscall) 48 49 /* Ok, we need to do extra processing, enter the slow path. */ 50fast_work_pending: 51 str r0, [sp, #S_R0+S_OFF]! @ returned r0 52 /* fall through to work_pending */ 53#else 54/* 55 * The "replacement" ret_fast_syscall for when tracing or context tracking 56 * is enabled. As we will need to call out to some C functions, we save 57 * r0 first to avoid needing to save registers around each C function call. 58 */ 59ret_fast_syscall: 60 UNWIND(.fnstart ) 61 UNWIND(.cantunwind ) 62 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 63 disable_irq_notrace @ disable interrupts 64 ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing 65 tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK 66 beq no_work_pending 67 UNWIND(.fnend ) 68ENDPROC(ret_fast_syscall) 69 70 /* Slower path - fall through to work_pending */ 71#endif 72 73 tst r1, #_TIF_SYSCALL_WORK 74 bne __sys_trace_return_nosave 75slow_work_pending: 76 mov r0, sp @ 'regs' 77 mov r2, why @ 'syscall' 78 bl do_work_pending 79 cmp r0, #0 80 beq no_work_pending 81 movlt scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE) 82 ldmia sp, {r0 - r6} @ have to reload r0 - r6 83 b local_restart @ ... and off we go 84ENDPROC(ret_fast_syscall) 85 86/* 87 * "slow" syscall return path. "why" tells us if this was a real syscall. 88 * IRQs may be enabled here, so always disable them. Note that we use the 89 * "notrace" version to avoid calling into the tracing code unnecessarily. 90 * do_work_pending() will update this state if necessary. 91 */ 92ENTRY(ret_to_user) 93ret_slow_syscall: 94 disable_irq_notrace @ disable interrupts 95ENTRY(ret_to_user_from_irq) 96 ldr r1, [tsk, #TI_FLAGS] 97 tst r1, #_TIF_WORK_MASK 98 bne slow_work_pending 99no_work_pending: 100 asm_trace_hardirqs_on save = 0 101 102 /* perform architecture specific actions before user return */ 103 arch_ret_to_user r1, lr 104 ct_user_enter save = 0 105 106 restore_user_regs fast = 0, offset = 0 107ENDPROC(ret_to_user_from_irq) 108ENDPROC(ret_to_user) 109 110/* 111 * This is how we return from a fork. 112 */ 113ENTRY(ret_from_fork) 114 bl schedule_tail 115 cmp r5, #0 116 movne r0, r4 117 badrne lr, 1f 118 retne r5 1191: get_thread_info tsk 120 b ret_slow_syscall 121ENDPROC(ret_from_fork) 122 123 .equ NR_syscalls,0 124#define CALL(x) .equ NR_syscalls,NR_syscalls+1 125#include "calls.S" 126 127/* 128 * Ensure that the system call table is equal to __NR_syscalls, 129 * which is the value the rest of the system sees 130 */ 131.ifne NR_syscalls - __NR_syscalls 132.error "__NR_syscalls is not equal to the size of the syscall table" 133.endif 134 135#undef CALL 136#define CALL(x) .long x 137 138/*============================================================================= 139 * SWI handler 140 *----------------------------------------------------------------------------- 141 */ 142 143 .align 5 144ENTRY(vector_swi) 145#ifdef CONFIG_CPU_V7M 146 v7m_exception_entry 147#else 148 sub sp, sp, #S_FRAME_SIZE 149 stmia sp, {r0 - r12} @ Calling r0 - r12 150 ARM( add r8, sp, #S_PC ) 151 ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr 152 THUMB( mov r8, sp ) 153 THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr 154 mrs r8, spsr @ called from non-FIQ mode, so ok. 155 str lr, [sp, #S_PC] @ Save calling PC 156 str r8, [sp, #S_PSR] @ Save CPSR 157 str r0, [sp, #S_OLD_R0] @ Save OLD_R0 158#endif 159 zero_fp 160 alignment_trap r10, ip, __cr_alignment 161 enable_irq 162 ct_user_exit 163 get_thread_info tsk 164 165 /* 166 * Get the system call number. 167 */ 168 169#if defined(CONFIG_OABI_COMPAT) 170 171 /* 172 * If we have CONFIG_OABI_COMPAT then we need to look at the swi 173 * value to determine if it is an EABI or an old ABI call. 174 */ 175#ifdef CONFIG_ARM_THUMB 176 tst r8, #PSR_T_BIT 177 movne r10, #0 @ no thumb OABI emulation 178 USER( ldreq r10, [lr, #-4] ) @ get SWI instruction 179#else 180 USER( ldr r10, [lr, #-4] ) @ get SWI instruction 181#endif 182 ARM_BE8(rev r10, r10) @ little endian instruction 183 184#elif defined(CONFIG_AEABI) 185 186 /* 187 * Pure EABI user space always put syscall number into scno (r7). 188 */ 189#elif defined(CONFIG_ARM_THUMB) 190 /* Legacy ABI only, possibly thumb mode. */ 191 tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs 192 addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in 193 USER( ldreq scno, [lr, #-4] ) 194 195#else 196 /* Legacy ABI only. */ 197 USER( ldr scno, [lr, #-4] ) @ get SWI instruction 198#endif 199 200 uaccess_disable tbl 201 202 adr tbl, sys_call_table @ load syscall table pointer 203 204#if defined(CONFIG_OABI_COMPAT) 205 /* 206 * If the swi argument is zero, this is an EABI call and we do nothing. 207 * 208 * If this is an old ABI call, get the syscall number into scno and 209 * get the old ABI syscall table address. 210 */ 211 bics r10, r10, #0xff000000 212 eorne scno, r10, #__NR_OABI_SYSCALL_BASE 213 ldrne tbl, =sys_oabi_call_table 214#elif !defined(CONFIG_AEABI) 215 bic scno, scno, #0xff000000 @ mask off SWI op-code 216 eor scno, scno, #__NR_SYSCALL_BASE @ check OS number 217#endif 218 219local_restart: 220 ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing 221 stmdb sp!, {r4, r5} @ push fifth and sixth args 222 223 tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? 224 bne __sys_trace 225 226 cmp scno, #NR_syscalls @ check upper syscall limit 227 badr lr, ret_fast_syscall @ return address 228 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 229 230 add r1, sp, #S_OFF 2312: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE) 232 eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back 233 bcs arm_syscall 234 mov why, #0 @ no longer a real syscall 235 b sys_ni_syscall @ not private func 236 237#if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) 238 /* 239 * We failed to handle a fault trying to access the page 240 * containing the swi instruction, but we're not really in a 241 * position to return -EFAULT. Instead, return back to the 242 * instruction and re-enter the user fault handling path trying 243 * to page it in. This will likely result in sending SEGV to the 244 * current task. 245 */ 2469001: 247 sub lr, lr, #4 248 str lr, [sp, #S_PC] 249 b ret_fast_syscall 250#endif 251ENDPROC(vector_swi) 252 253 /* 254 * This is the really slow path. We're going to be doing 255 * context switches, and waiting for our parent to respond. 256 */ 257__sys_trace: 258 mov r1, scno 259 add r0, sp, #S_OFF 260 bl syscall_trace_enter 261 262 badr lr, __sys_trace_return @ return address 263 mov scno, r0 @ syscall number (possibly new) 264 add r1, sp, #S_R0 + S_OFF @ pointer to regs 265 cmp scno, #NR_syscalls @ check upper syscall limit 266 ldmccia r1, {r0 - r6} @ have to reload r0 - r6 267 stmccia sp, {r4, r5} @ and update the stack args 268 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 269 cmp scno, #-1 @ skip the syscall? 270 bne 2b 271 add sp, sp, #S_OFF @ restore stack 272 b ret_slow_syscall 273 274__sys_trace_return: 275 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 276 mov r0, sp 277 bl syscall_trace_exit 278 b ret_slow_syscall 279 280__sys_trace_return_nosave: 281 enable_irq_notrace 282 mov r0, sp 283 bl syscall_trace_exit 284 b ret_slow_syscall 285 286 .align 5 287#ifdef CONFIG_ALIGNMENT_TRAP 288 .type __cr_alignment, #object 289__cr_alignment: 290 .word cr_alignment 291#endif 292 .ltorg 293 294/* 295 * This is the syscall table declaration for native ABI syscalls. 296 * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall. 297 */ 298#define ABI(native, compat) native 299#ifdef CONFIG_AEABI 300#define OBSOLETE(syscall) sys_ni_syscall 301#else 302#define OBSOLETE(syscall) syscall 303#endif 304 305 .type sys_call_table, #object 306ENTRY(sys_call_table) 307#include "calls.S" 308#undef ABI 309#undef OBSOLETE 310 311/*============================================================================ 312 * Special system call wrappers 313 */ 314@ r0 = syscall number 315@ r8 = syscall table 316sys_syscall: 317 bic scno, r0, #__NR_OABI_SYSCALL_BASE 318 cmp scno, #__NR_syscall - __NR_SYSCALL_BASE 319 cmpne scno, #NR_syscalls @ check range 320 stmloia sp, {r5, r6} @ shuffle args 321 movlo r0, r1 322 movlo r1, r2 323 movlo r2, r3 324 movlo r3, r4 325 ldrlo pc, [tbl, scno, lsl #2] 326 b sys_ni_syscall 327ENDPROC(sys_syscall) 328 329sys_sigreturn_wrapper: 330 add r0, sp, #S_OFF 331 mov why, #0 @ prevent syscall restart handling 332 b sys_sigreturn 333ENDPROC(sys_sigreturn_wrapper) 334 335sys_rt_sigreturn_wrapper: 336 add r0, sp, #S_OFF 337 mov why, #0 @ prevent syscall restart handling 338 b sys_rt_sigreturn 339ENDPROC(sys_rt_sigreturn_wrapper) 340 341sys_statfs64_wrapper: 342 teq r1, #88 343 moveq r1, #84 344 b sys_statfs64 345ENDPROC(sys_statfs64_wrapper) 346 347sys_fstatfs64_wrapper: 348 teq r1, #88 349 moveq r1, #84 350 b sys_fstatfs64 351ENDPROC(sys_fstatfs64_wrapper) 352 353/* 354 * Note: off_4k (r5) is always units of 4K. If we can't do the requested 355 * offset, we return EINVAL. 356 */ 357sys_mmap2: 358#if PAGE_SHIFT > 12 359 tst r5, #PGOFF_MASK 360 moveq r5, r5, lsr #PAGE_SHIFT - 12 361 streq r5, [sp, #4] 362 beq sys_mmap_pgoff 363 mov r0, #-EINVAL 364 ret lr 365#else 366 str r5, [sp, #4] 367 b sys_mmap_pgoff 368#endif 369ENDPROC(sys_mmap2) 370 371#ifdef CONFIG_OABI_COMPAT 372 373/* 374 * These are syscalls with argument register differences 375 */ 376 377sys_oabi_pread64: 378 stmia sp, {r3, r4} 379 b sys_pread64 380ENDPROC(sys_oabi_pread64) 381 382sys_oabi_pwrite64: 383 stmia sp, {r3, r4} 384 b sys_pwrite64 385ENDPROC(sys_oabi_pwrite64) 386 387sys_oabi_truncate64: 388 mov r3, r2 389 mov r2, r1 390 b sys_truncate64 391ENDPROC(sys_oabi_truncate64) 392 393sys_oabi_ftruncate64: 394 mov r3, r2 395 mov r2, r1 396 b sys_ftruncate64 397ENDPROC(sys_oabi_ftruncate64) 398 399sys_oabi_readahead: 400 str r3, [sp] 401 mov r3, r2 402 mov r2, r1 403 b sys_readahead 404ENDPROC(sys_oabi_readahead) 405 406/* 407 * Let's declare a second syscall table for old ABI binaries 408 * using the compatibility syscall entries. 409 */ 410#define ABI(native, compat) compat 411#define OBSOLETE(syscall) syscall 412 413 .type sys_oabi_call_table, #object 414ENTRY(sys_oabi_call_table) 415#include "calls.S" 416#undef ABI 417#undef OBSOLETE 418 419#endif 420 421