arch/arm/kernel/entry-common.S

   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 #ifdef CONFIG_AEABI
  16 #include <asm/unistd-oabi.h>
  17 #endif
  18
  19         .equ    NR_syscalls, __NR_syscalls
  20
  21 #ifdef CONFIG_NEED_RET_TO_USER
  22 #include <mach/entry-macro.S>
  23 #else
  24         .macro  arch_ret_to_user, tmp1, tmp2
  25         .endm
  26 #endif
  27
  28 #include "entry-header.S"
  29
  30
  31         .align  5
  32 #if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING))
  33 /*
  34  * This is the fast syscall return path.  We do as little as possible here,
  35  * such as avoiding writing r0 to the stack.  We only use this path if we
  36  * have tracing and context tracking disabled - the overheads from those
  37  * features make this path too inefficient.
  38  */
  39 ret_fast_syscall:
  40  UNWIND(.fnstart        )
  41  UNWIND(.cantunwind     )
  42         disable_irq_notrace                     @ disable interrupts
  43         ldr     r1, [tsk, #TI_FLAGS]            @ re-check for syscall tracing
  44         tst     r1, #_TIF_SYSCALL_WORK
  45         bne     fast_work_pending
  46         tst     r1, #_TIF_WORK_MASK
  47         bne     fast_work_pending
  48
  49         /* perform architecture specific actions before user return */
  50         arch_ret_to_user r1, lr
  51
  52         restore_user_regs fast = 1, offset = S_OFF
  53  UNWIND(.fnend          )
  54 ENDPROC(ret_fast_syscall)
  55
  56         /* Ok, we need to do extra processing, enter the slow path. */
  57 fast_work_pending:
  58         str     r0, [sp, #S_R0+S_OFF]!          @ returned r0
  59         /* fall through to work_pending */
  60 #else
  61 /*
  62  * The "replacement" ret_fast_syscall for when tracing or context tracking
  63  * is enabled.  As we will need to call out to some C functions, we save
  64  * r0 first to avoid needing to save registers around each C function call.
  65  */
  66 ret_fast_syscall:
  67  UNWIND(.fnstart        )
  68  UNWIND(.cantunwind     )
  69         str     r0, [sp, #S_R0 + S_OFF]!        @ save returned r0
  70         disable_irq_notrace                     @ disable interrupts
  71         ldr     r1, [tsk, #TI_FLAGS]            @ re-check for syscall tracing
  72         tst     r1, #_TIF_SYSCALL_WORK
  73         bne     fast_work_pending
  74         tst     r1, #_TIF_WORK_MASK
  75         beq     no_work_pending
  76  UNWIND(.fnend          )
  77 ENDPROC(ret_fast_syscall)
  78
  79         /* Slower path - fall through to work_pending */
  80 fast_work_pending:
  81 #endif
  82
  83         tst     r1, #_TIF_SYSCALL_WORK
  84         bne     __sys_trace_return_nosave
  85 slow_work_pending:
  86         mov     r0, sp                          @ 'regs'
  87         mov     r2, why                         @ 'syscall'
  88         bl      do_work_pending
  89         cmp     r0, #0
  90         beq     no_work_pending
  91         movlt   scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
  92         ldmia   sp, {r0 - r6}                   @ have to reload r0 - r6
  93         b       local_restart                   @ ... and off we go
  94 ENDPROC(ret_fast_syscall)
  95
  96 /*
  97  * "slow" syscall return path.  "why" tells us if this was a real syscall.
  98  * IRQs may be enabled here, so always disable them.  Note that we use the
  99  * "notrace" version to avoid calling into the tracing code unnecessarily.
 100  * do_work_pending() will update this state if necessary.
 101  */
 102 ENTRY(ret_to_user)
 103 ret_slow_syscall:
 104         disable_irq_notrace                     @ disable interrupts
 105 ENTRY(ret_to_user_from_irq)
 106         ldr     r1, [tsk, #TI_FLAGS]
 107         tst     r1, #_TIF_WORK_MASK
 108         bne     slow_work_pending
 109 no_work_pending:
 110         asm_trace_hardirqs_on save = 0
 111
 112         /* perform architecture specific actions before user return */
 113         arch_ret_to_user r1, lr
 114         ct_user_enter save = 0
 115
 116         restore_user_regs fast = 0, offset = 0
 117 ENDPROC(ret_to_user_from_irq)
 118 ENDPROC(ret_to_user)
 119
 120 /*
 121  * This is how we return from a fork.
 122  */
 123 ENTRY(ret_from_fork)
 124         bl      schedule_tail
 125         cmp     r5, #0
 126         movne   r0, r4
 127         badrne  lr, 1f
 128         retne   r5
 129 1:      get_thread_info tsk
 130         b       ret_slow_syscall
 131 ENDPROC(ret_from_fork)
 132
 133 /*=============================================================================
 134  * SWI handler
 135  *-----------------------------------------------------------------------------
 136  */
 137
 138         .align  5
 139 ENTRY(vector_swi)
 140 #ifdef CONFIG_CPU_V7M
 141         v7m_exception_entry
 142 #else
 143         sub     sp, sp, #PT_REGS_SIZE
 144         stmia   sp, {r0 - r12}                  @ Calling r0 - r12
 145  ARM(   add     r8, sp, #S_PC           )
 146  ARM(   stmdb   r8, {sp, lr}^           )       @ Calling sp, lr
 147  THUMB( mov     r8, sp                  )
 148  THUMB( store_user_sp_lr r8, r10, S_SP  )       @ calling sp, lr
 149         mrs     r8, spsr                        @ called from non-FIQ mode, so ok.
 150         str     lr, [sp, #S_PC]                 @ Save calling PC
 151         str     r8, [sp, #S_PSR]                @ Save CPSR
 152         str     r0, [sp, #S_OLD_R0]             @ Save OLD_R0
 153 #endif
 154         zero_fp
 155         alignment_trap r10, ip, __cr_alignment
 156         enable_irq
 157         ct_user_exit
 158         get_thread_info tsk
 159
 160         /*
 161          * Get the system call number.
 162          */
 163
 164 #if defined(CONFIG_OABI_COMPAT)
 165
 166         /*
 167          * If we have CONFIG_OABI_COMPAT then we need to look at the swi
 168          * value to determine if it is an EABI or an old ABI call.
 169          */
 170 #ifdef CONFIG_ARM_THUMB
 171         tst     r8, #PSR_T_BIT
 172         movne   r10, #0                         @ no thumb OABI emulation
 173  USER(  ldreq   r10, [lr, #-4]          )       @ get SWI instruction
 174 #else
 175  USER(  ldr     r10, [lr, #-4]          )       @ get SWI instruction
 176 #endif
 177  ARM_BE8(rev    r10, r10)                       @ little endian instruction
 178
 179 #elif defined(CONFIG_AEABI)
 180
 181         /*
 182          * Pure EABI user space always put syscall number into scno (r7).
 183          */
 184 #elif defined(CONFIG_ARM_THUMB)
 185         /* Legacy ABI only, possibly thumb mode. */
 186         tst     r8, #PSR_T_BIT                  @ this is SPSR from save_user_regs
 187         addne   scno, r7, #__NR_SYSCALL_BASE    @ put OS number in
 188  USER(  ldreq   scno, [lr, #-4]         )
 189
 190 #else
 191         /* Legacy ABI only. */
 192  USER(  ldr     scno, [lr, #-4]         )       @ get SWI instruction
 193 #endif
 194
 195         uaccess_disable tbl
 196
 197         adr     tbl, sys_call_table             @ load syscall table pointer
 198
 199 #if defined(CONFIG_OABI_COMPAT)
 200         /*
 201          * If the swi argument is zero, this is an EABI call and we do nothing.
 202          *
 203          * If this is an old ABI call, get the syscall number into scno and
 204          * get the old ABI syscall table address.
 205          */
 206         bics    r10, r10, #0xff000000
 207         eorne   scno, r10, #__NR_OABI_SYSCALL_BASE
 208         ldrne   tbl, =sys_oabi_call_table
 209 #elif !defined(CONFIG_AEABI)
 210         bic     scno, scno, #0xff000000         @ mask off SWI op-code
 211         eor     scno, scno, #__NR_SYSCALL_BASE  @ check OS number
 212 #endif
 213
 214 local_restart:
 215         ldr     r10, [tsk, #TI_FLAGS]           @ check for syscall tracing
 216         stmdb   sp!, {r4, r5}                   @ push fifth and sixth args
 217
 218         tst     r10, #_TIF_SYSCALL_WORK         @ are we tracing syscalls?
 219         bne     __sys_trace
 220
 221         cmp     scno, #NR_syscalls              @ check upper syscall limit
 222         badr    lr, ret_fast_syscall            @ return address
 223         ldrcc   pc, [tbl, scno, lsl #2]         @ call sys_* routine
 224
 225         add     r1, sp, #S_OFF
 226 2:      cmp     scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
 227         eor     r0, scno, #__NR_SYSCALL_BASE    @ put OS number back
 228         bcs     arm_syscall
 229         mov     why, #0                         @ no longer a real syscall
 230         b       sys_ni_syscall                  @ not private func
 231
 232 #if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
 233         /*
 234          * We failed to handle a fault trying to access the page
 235          * containing the swi instruction, but we're not really in a
 236          * position to return -EFAULT. Instead, return back to the
 237          * instruction and re-enter the user fault handling path trying
 238          * to page it in. This will likely result in sending SEGV to the
 239          * current task.
 240          */
 241 9001:
 242         sub     lr, lr, #4
 243         str     lr, [sp, #S_PC]
 244         b       ret_fast_syscall
 245 #endif
 246 ENDPROC(vector_swi)
 247
 248         /*
 249          * This is the really slow path.  We're going to be doing
 250          * context switches, and waiting for our parent to respond.
 251          */
 252 __sys_trace:
 253         mov     r1, scno
 254         add     r0, sp, #S_OFF
 255         bl      syscall_trace_enter
 256
 257         badr    lr, __sys_trace_return          @ return address
 258         mov     scno, r0                        @ syscall number (possibly new)
 259         add     r1, sp, #S_R0 + S_OFF           @ pointer to regs
 260         cmp     scno, #NR_syscalls              @ check upper syscall limit
 261         ldmccia r1, {r0 - r6}                   @ have to reload r0 - r6
 262         stmccia sp, {r4, r5}                    @ and update the stack args
 263         ldrcc   pc, [tbl, scno, lsl #2]         @ call sys_* routine
 264         cmp     scno, #-1                       @ skip the syscall?
 265         bne     2b
 266         add     sp, sp, #S_OFF                  @ restore stack
 267         b       ret_slow_syscall
 268
 269 __sys_trace_return:
 270         str     r0, [sp, #S_R0 + S_OFF]!        @ save returned r0
 271         mov     r0, sp
 272         bl      syscall_trace_exit
 273         b       ret_slow_syscall
 274
 275 __sys_trace_return_nosave:
 276         enable_irq_notrace
 277         mov     r0, sp
 278         bl      syscall_trace_exit
 279         b       ret_slow_syscall
 280
 281         .align  5
 282 #ifdef CONFIG_ALIGNMENT_TRAP
 283         .type   __cr_alignment, #object
 284 __cr_alignment:
 285         .word   cr_alignment
 286 #endif
 287         .ltorg
 288
 289         .macro  syscall_table_start, sym
 290         .equ    __sys_nr, 0
 291         .type   \sym, #object
 292 ENTRY(\sym)
 293         .endm
 294
 295         .macro  syscall, nr, func
 296         .ifgt   __sys_nr - \nr
 297         .error  "Duplicated/unorded system call entry"
 298         .endif
 299         .rept   \nr - __sys_nr
 300         .long   sys_ni_syscall
 301         .endr
 302         .long   \func
 303         .equ    __sys_nr, \nr + 1
 304         .endm
 305
 306         .macro  syscall_table_end, sym
 307         .ifgt   __sys_nr - __NR_syscalls
 308         .error  "System call table too big"
 309         .endif
 310         .rept   __NR_syscalls - __sys_nr
 311         .long   sys_ni_syscall
 312         .endr
 313         .size   \sym, . - \sym
 314         .endm
 315
 316 #define NATIVE(nr, func) syscall nr, func
 317
 318 /*
 319  * This is the syscall table declaration for native ABI syscalls.
 320  * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
 321  */
 322         syscall_table_start sys_call_table
 323 #define COMPAT(nr, native, compat) syscall nr, native
 324 #ifdef CONFIG_AEABI
 325 #include <calls-eabi.S>
 326 #else
 327 #include <calls-oabi.S>
 328 #endif
 329 #undef COMPAT
 330         syscall_table_end sys_call_table
 331
 332 /*============================================================================
 333  * Special system call wrappers
 334  */
 335 @ r0 = syscall number
 336 @ r8 = syscall table
 337 sys_syscall:
 338                 bic     scno, r0, #__NR_OABI_SYSCALL_BASE
 339                 cmp     scno, #__NR_syscall - __NR_SYSCALL_BASE
 340                 cmpne   scno, #NR_syscalls      @ check range
 341                 stmloia sp, {r5, r6}            @ shuffle args
 342                 movlo   r0, r1
 343                 movlo   r1, r2
 344                 movlo   r2, r3
 345                 movlo   r3, r4
 346                 ldrlo   pc, [tbl, scno, lsl #2]
 347                 b       sys_ni_syscall
 348 ENDPROC(sys_syscall)
 349
 350 sys_sigreturn_wrapper:
 351                 add     r0, sp, #S_OFF
 352                 mov     why, #0         @ prevent syscall restart handling
 353                 b       sys_sigreturn
 354 ENDPROC(sys_sigreturn_wrapper)
 355
 356 sys_rt_sigreturn_wrapper:
 357                 add     r0, sp, #S_OFF
 358                 mov     why, #0         @ prevent syscall restart handling
 359                 b       sys_rt_sigreturn
 360 ENDPROC(sys_rt_sigreturn_wrapper)
 361
 362 sys_statfs64_wrapper:
 363                 teq     r1, #88
 364                 moveq   r1, #84
 365                 b       sys_statfs64
 366 ENDPROC(sys_statfs64_wrapper)
 367
 368 sys_fstatfs64_wrapper:
 369                 teq     r1, #88
 370                 moveq   r1, #84
 371                 b       sys_fstatfs64
 372 ENDPROC(sys_fstatfs64_wrapper)
 373
 374 /*
 375  * Note: off_4k (r5) is always units of 4K.  If we can't do the requested
 376  * offset, we return EINVAL.
 377  */
 378 sys_mmap2:
 379 #if PAGE_SHIFT > 12
 380                 tst     r5, #PGOFF_MASK
 381                 moveq   r5, r5, lsr #PAGE_SHIFT - 12
 382                 streq   r5, [sp, #4]
 383                 beq     sys_mmap_pgoff
 384                 mov     r0, #-EINVAL
 385                 ret     lr
 386 #else
 387                 str     r5, [sp, #4]
 388                 b       sys_mmap_pgoff
 389 #endif
 390 ENDPROC(sys_mmap2)
 391
 392 #ifdef CONFIG_OABI_COMPAT
 393
 394 /*
 395  * These are syscalls with argument register differences
 396  */
 397
 398 sys_oabi_pread64:
 399                 stmia   sp, {r3, r4}
 400                 b       sys_pread64
 401 ENDPROC(sys_oabi_pread64)
 402
 403 sys_oabi_pwrite64:
 404                 stmia   sp, {r3, r4}
 405                 b       sys_pwrite64
 406 ENDPROC(sys_oabi_pwrite64)
 407
 408 sys_oabi_truncate64:
 409                 mov     r3, r2
 410                 mov     r2, r1
 411                 b       sys_truncate64
 412 ENDPROC(sys_oabi_truncate64)
 413
 414 sys_oabi_ftruncate64:
 415                 mov     r3, r2
 416                 mov     r2, r1
 417                 b       sys_ftruncate64
 418 ENDPROC(sys_oabi_ftruncate64)
 419
 420 sys_oabi_readahead:
 421                 str     r3, [sp]
 422                 mov     r3, r2
 423                 mov     r2, r1
 424                 b       sys_readahead
 425 ENDPROC(sys_oabi_readahead)
 426
 427 /*
 428  * Let's declare a second syscall table for old ABI binaries
 429  * using the compatibility syscall entries.
 430  */
 431         syscall_table_start sys_oabi_call_table
 432 #define COMPAT(nr, native, compat) syscall nr, compat
 433 #include <calls-oabi.S>
 434         syscall_table_end sys_oabi_call_table
 435
 436 #endif
 437