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
  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  */
  34 ret_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          )
  47 ENDPROC(ret_fast_syscall)
  48
  49         /* Ok, we need to do extra processing, enter the slow path. */
  50 fast_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  */
  59 ret_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          )
  68 ENDPROC(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
  75 slow_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
  84 ENDPROC(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  */
  92 ENTRY(ret_to_user)
  93 ret_slow_syscall:
  94         disable_irq_notrace                     @ disable interrupts
  95 ENTRY(ret_to_user_from_irq)
  96         ldr     r1, [tsk, #TI_FLAGS]
  97         tst     r1, #_TIF_WORK_MASK
  98         bne     slow_work_pending
  99 no_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
 107 ENDPROC(ret_to_user_from_irq)
 108 ENDPROC(ret_to_user)
 109
 110 /*
 111  * This is how we return from a fork.
 112  */
 113 ENTRY(ret_from_fork)
 114         bl      schedule_tail
 115         cmp     r5, #0
 116         movne   r0, r4
 117         badrne  lr, 1f
 118         retne   r5
 119 1:      get_thread_info tsk
 120         b       ret_slow_syscall
 121 ENDPROC(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
 144 ENTRY(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
 219 local_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
 231 2:      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          */
 246 9001:
 247         sub     lr, lr, #4
 248         str     lr, [sp, #S_PC]
 249         b       ret_fast_syscall
 250 #endif
 251 ENDPROC(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
 306 ENTRY(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
 316 sys_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
 327 ENDPROC(sys_syscall)
 328
 329 sys_sigreturn_wrapper:
 330                 add     r0, sp, #S_OFF
 331                 mov     why, #0         @ prevent syscall restart handling
 332                 b       sys_sigreturn
 333 ENDPROC(sys_sigreturn_wrapper)
 334
 335 sys_rt_sigreturn_wrapper:
 336                 add     r0, sp, #S_OFF
 337                 mov     why, #0         @ prevent syscall restart handling
 338                 b       sys_rt_sigreturn
 339 ENDPROC(sys_rt_sigreturn_wrapper)
 340
 341 sys_statfs64_wrapper:
 342                 teq     r1, #88
 343                 moveq   r1, #84
 344                 b       sys_statfs64
 345 ENDPROC(sys_statfs64_wrapper)
 346
 347 sys_fstatfs64_wrapper:
 348                 teq     r1, #88
 349                 moveq   r1, #84
 350                 b       sys_fstatfs64
 351 ENDPROC(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  */
 357 sys_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
 369 ENDPROC(sys_mmap2)
 370
 371 #ifdef CONFIG_OABI_COMPAT
 372
 373 /*
 374  * These are syscalls with argument register differences
 375  */
 376
 377 sys_oabi_pread64:
 378                 stmia   sp, {r3, r4}
 379                 b       sys_pread64
 380 ENDPROC(sys_oabi_pread64)
 381
 382 sys_oabi_pwrite64:
 383                 stmia   sp, {r3, r4}
 384                 b       sys_pwrite64
 385 ENDPROC(sys_oabi_pwrite64)
 386
 387 sys_oabi_truncate64:
 388                 mov     r3, r2
 389                 mov     r2, r1
 390                 b       sys_truncate64
 391 ENDPROC(sys_oabi_truncate64)
 392
 393 sys_oabi_ftruncate64:
 394                 mov     r3, r2
 395                 mov     r2, r1
 396                 b       sys_ftruncate64
 397 ENDPROC(sys_oabi_ftruncate64)
 398
 399 sys_oabi_readahead:
 400                 str     r3, [sp]
 401                 mov     r3, r2
 402                 mov     r2, r1
 403                 b       sys_readahead
 404 ENDPROC(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
 414 ENTRY(sys_oabi_call_table)
 415 #include "calls.S"
 416 #undef ABI
 417 #undef OBSOLETE
 418
 419 #endif
 420