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/unistd.h>
  12 #include <asm/ftrace.h>
  13 #include <asm/unwind.h>
  14
  15 #ifdef CONFIG_NEED_RET_TO_USER
  16 #include <mach/entry-macro.S>
  17 #else
  18         .macro  arch_ret_to_user, tmp1, tmp2
  19         .endm
  20 #endif
  21
  22 #include "entry-header.S"
  23
  24
  25         .align  5
  26 /*
  27  * This is the fast syscall return path.  We do as little as
  28  * possible here, and this includes saving r0 back into the SVC
  29  * stack.
  30  */
  31 ret_fast_syscall:
  32  UNWIND(.fnstart        )
  33  UNWIND(.cantunwind     )
  34         disable_irq                             @ disable interrupts
  35         ldr     r1, [tsk, #TI_FLAGS]
  36         tst     r1, #_TIF_WORK_MASK
  37         bne     fast_work_pending
  38         asm_trace_hardirqs_on
  39
  40         /* perform architecture specific actions before user return */
  41         arch_ret_to_user r1, lr
  42         ct_user_enter
  43
  44         restore_user_regs fast = 1, offset = S_OFF
  45  UNWIND(.fnend          )
  46
  47 /*
  48  * Ok, we need to do extra processing, enter the slow path.
  49  */
  50 fast_work_pending:
  51         str     r0, [sp, #S_R0+S_OFF]!          @ returned r0
  52 work_pending:
  53         mov     r0, sp                          @ 'regs'
  54         mov     r2, why                         @ 'syscall'
  55         bl      do_work_pending
  56         cmp     r0, #0
  57         beq     no_work_pending
  58         movlt   scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
  59         ldmia   sp, {r0 - r6}                   @ have to reload r0 - r6
  60         b       local_restart                   @ ... and off we go
  61
  62 /*
  63  * "slow" syscall return path.  "why" tells us if this was a real syscall.
  64  */
  65 ENTRY(ret_to_user)
  66 ret_slow_syscall:
  67         disable_irq                             @ disable interrupts
  68 ENTRY(ret_to_user_from_irq)
  69         ldr     r1, [tsk, #TI_FLAGS]
  70         tst     r1, #_TIF_WORK_MASK
  71         bne     work_pending
  72 no_work_pending:
  73         asm_trace_hardirqs_on
  74
  75         /* perform architecture specific actions before user return */
  76         arch_ret_to_user r1, lr
  77         ct_user_enter save = 0
  78
  79         restore_user_regs fast = 0, offset = 0
  80 ENDPROC(ret_to_user_from_irq)
  81 ENDPROC(ret_to_user)
  82
  83 /*
  84  * This is how we return from a fork.
  85  */
  86 ENTRY(ret_from_fork)
  87         bl      schedule_tail
  88         cmp     r5, #0
  89         movne   r0, r4
  90         adrne   lr, BSYM(1f)
  91         movne   pc, r5
  92 1:      get_thread_info tsk
  93         b       ret_slow_syscall
  94 ENDPROC(ret_from_fork)
  95
  96         .equ NR_syscalls,0
  97 #define CALL(x) .equ NR_syscalls,NR_syscalls+1
  98 #include "calls.S"
  99
 100 /*
 101  * Ensure that the system call table is equal to __NR_syscalls,
 102  * which is the value the rest of the system sees
 103  */
 104 .ifne NR_syscalls - __NR_syscalls
 105 .error "__NR_syscalls is not equal to the size of the syscall table"
 106 .endif
 107
 108 #undef CALL
 109 #define CALL(x) .long x
 110
 111 #ifdef CONFIG_FUNCTION_TRACER
 112 /*
 113  * When compiling with -pg, gcc inserts a call to the mcount routine at the
 114  * start of every function.  In mcount, apart from the function's address (in
 115  * lr), we need to get hold of the function's caller's address.
 116  *
 117  * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
 118  *
 119  *      bl      mcount
 120  *
 121  * These versions have the limitation that in order for the mcount routine to
 122  * be able to determine the function's caller's address, an APCS-style frame
 123  * pointer (which is set up with something like the code below) is required.
 124  *
 125  *      mov     ip, sp
 126  *      push    {fp, ip, lr, pc}
 127  *      sub     fp, ip, #4
 128  *
 129  * With EABI, these frame pointers are not available unless -mapcs-frame is
 130  * specified, and if building as Thumb-2, not even then.
 131  *
 132  * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
 133  * with call sites like:
 134  *
 135  *      push    {lr}
 136  *      bl      __gnu_mcount_nc
 137  *
 138  * With these compilers, frame pointers are not necessary.
 139  *
 140  * mcount can be thought of as a function called in the middle of a subroutine
 141  * call.  As such, it needs to be transparent for both the caller and the
 142  * callee: the original lr needs to be restored when leaving mcount, and no
 143  * registers should be clobbered.  (In the __gnu_mcount_nc implementation, we
 144  * clobber the ip register.  This is OK because the ARM calling convention
 145  * allows it to be clobbered in subroutines and doesn't use it to hold
 146  * parameters.)
 147  *
 148  * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
 149  * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
 150  * arch/arm/kernel/ftrace.c).
 151  */
 152
 153 #ifndef CONFIG_OLD_MCOUNT
 154 #if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
 155 #error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
 156 #endif
 157 #endif
 158
 159 .macro mcount_adjust_addr rd, rn
 160         bic     \rd, \rn, #1            @ clear the Thumb bit if present
 161         sub     \rd, \rd, #MCOUNT_INSN_SIZE
 162 .endm
 163
 164 .macro __mcount suffix
 165         mcount_enter
 166         ldr     r0, =ftrace_trace_function
 167         ldr     r2, [r0]
 168         adr     r0, .Lftrace_stub
 169         cmp     r0, r2
 170         bne     1f
 171
 172 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 173         ldr     r1, =ftrace_graph_return
 174         ldr     r2, [r1]
 175         cmp     r0, r2
 176         bne     ftrace_graph_caller\suffix
 177
 178         ldr     r1, =ftrace_graph_entry
 179         ldr     r2, [r1]
 180         ldr     r0, =ftrace_graph_entry_stub
 181         cmp     r0, r2
 182         bne     ftrace_graph_caller\suffix
 183 #endif
 184
 185         mcount_exit
 186
 187 1:      mcount_get_lr   r1                      @ lr of instrumented func
 188         mcount_adjust_addr      r0, lr          @ instrumented function
 189         adr     lr, BSYM(2f)
 190         mov     pc, r2
 191 2:      mcount_exit
 192 .endm
 193
 194 .macro __ftrace_caller suffix
 195         mcount_enter
 196
 197         mcount_get_lr   r1                      @ lr of instrumented func
 198         mcount_adjust_addr      r0, lr          @ instrumented function
 199
 200         .globl ftrace_call\suffix
 201 ftrace_call\suffix:
 202         bl      ftrace_stub
 203
 204 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 205         .globl ftrace_graph_call\suffix
 206 ftrace_graph_call\suffix:
 207         mov     r0, r0
 208 #endif
 209
 210         mcount_exit
 211 .endm
 212
 213 .macro __ftrace_graph_caller
 214         sub     r0, fp, #4              @ &lr of instrumented routine (&parent)
 215 #ifdef CONFIG_DYNAMIC_FTRACE
 216         @ called from __ftrace_caller, saved in mcount_enter
 217         ldr     r1, [sp, #16]           @ instrumented routine (func)
 218         mcount_adjust_addr      r1, r1
 219 #else
 220         @ called from __mcount, untouched in lr
 221         mcount_adjust_addr      r1, lr  @ instrumented routine (func)
 222 #endif
 223         mov     r2, fp                  @ frame pointer
 224         bl      prepare_ftrace_return
 225         mcount_exit
 226 .endm
 227
 228 #ifdef CONFIG_OLD_MCOUNT
 229 /*
 230  * mcount
 231  */
 232
 233 .macro mcount_enter
 234         stmdb   sp!, {r0-r3, lr}
 235 .endm
 236
 237 .macro mcount_get_lr reg
 238         ldr     \reg, [fp, #-4]
 239 .endm
 240
 241 .macro mcount_exit
 242         ldr     lr, [fp, #-4]
 243         ldmia   sp!, {r0-r3, pc}
 244 .endm
 245
 246 ENTRY(mcount)
 247 #ifdef CONFIG_DYNAMIC_FTRACE
 248         stmdb   sp!, {lr}
 249         ldr     lr, [fp, #-4]
 250         ldmia   sp!, {pc}
 251 #else
 252         __mcount _old
 253 #endif
 254 ENDPROC(mcount)
 255
 256 #ifdef CONFIG_DYNAMIC_FTRACE
 257 ENTRY(ftrace_caller_old)
 258         __ftrace_caller _old
 259 ENDPROC(ftrace_caller_old)
 260 #endif
 261
 262 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 263 ENTRY(ftrace_graph_caller_old)
 264         __ftrace_graph_caller
 265 ENDPROC(ftrace_graph_caller_old)
 266 #endif
 267
 268 .purgem mcount_enter
 269 .purgem mcount_get_lr
 270 .purgem mcount_exit
 271 #endif
 272
 273 /*
 274  * __gnu_mcount_nc
 275  */
 276
 277 .macro mcount_enter
 278 /*
 279  * This pad compensates for the push {lr} at the call site.  Note that we are
 280  * unable to unwind through a function which does not otherwise save its lr.
 281  */
 282  UNWIND(.pad    #4)
 283         stmdb   sp!, {r0-r3, lr}
 284  UNWIND(.save   {r0-r3, lr})
 285 .endm
 286
 287 .macro mcount_get_lr reg
 288         ldr     \reg, [sp, #20]
 289 .endm
 290
 291 .macro mcount_exit
 292         ldmia   sp!, {r0-r3, ip, lr}
 293         mov     pc, ip
 294 .endm
 295
 296 ENTRY(__gnu_mcount_nc)
 297 UNWIND(.fnstart)
 298 #ifdef CONFIG_DYNAMIC_FTRACE
 299         mov     ip, lr
 300         ldmia   sp!, {lr}
 301         mov     pc, ip
 302 #else
 303         __mcount
 304 #endif
 305 UNWIND(.fnend)
 306 ENDPROC(__gnu_mcount_nc)
 307
 308 #ifdef CONFIG_DYNAMIC_FTRACE
 309 ENTRY(ftrace_caller)
 310 UNWIND(.fnstart)
 311         __ftrace_caller
 312 UNWIND(.fnend)
 313 ENDPROC(ftrace_caller)
 314 #endif
 315
 316 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 317 ENTRY(ftrace_graph_caller)
 318 UNWIND(.fnstart)
 319         __ftrace_graph_caller
 320 UNWIND(.fnend)
 321 ENDPROC(ftrace_graph_caller)
 322 #endif
 323
 324 .purgem mcount_enter
 325 .purgem mcount_get_lr
 326 .purgem mcount_exit
 327
 328 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 329         .globl return_to_handler
 330 return_to_handler:
 331         stmdb   sp!, {r0-r3}
 332         mov     r0, fp                  @ frame pointer
 333         bl      ftrace_return_to_handler
 334         mov     lr, r0                  @ r0 has real ret addr
 335         ldmia   sp!, {r0-r3}
 336         mov     pc, lr
 337 #endif
 338
 339 ENTRY(ftrace_stub)
 340 .Lftrace_stub:
 341         mov     pc, lr
 342 ENDPROC(ftrace_stub)
 343
 344 #endif /* CONFIG_FUNCTION_TRACER */
 345
 346 /*=============================================================================
 347  * SWI handler
 348  *-----------------------------------------------------------------------------
 349  */
 350
 351         .align  5
 352 ENTRY(vector_swi)
 353 #ifdef CONFIG_CPU_V7M
 354         v7m_exception_entry
 355 #else
 356         sub     sp, sp, #S_FRAME_SIZE
 357         stmia   sp, {r0 - r12}                  @ Calling r0 - r12
 358  ARM(   add     r8, sp, #S_PC           )
 359  ARM(   stmdb   r8, {sp, lr}^           )       @ Calling sp, lr
 360  THUMB( mov     r8, sp                  )
 361  THUMB( store_user_sp_lr r8, r10, S_SP  )       @ calling sp, lr
 362         mrs     r8, spsr                        @ called from non-FIQ mode, so ok.
 363         str     lr, [sp, #S_PC]                 @ Save calling PC
 364         str     r8, [sp, #S_PSR]                @ Save CPSR
 365         str     r0, [sp, #S_OLD_R0]             @ Save OLD_R0
 366 #endif
 367         zero_fp
 368
 369 #ifdef CONFIG_ALIGNMENT_TRAP
 370         ldr     ip, __cr_alignment
 371         ldr     ip, [ip]
 372         mcr     p15, 0, ip, c1, c0              @ update control register
 373 #endif
 374
 375         enable_irq
 376         ct_user_exit
 377         get_thread_info tsk
 378
 379         /*
 380          * Get the system call number.
 381          */
 382
 383 #if defined(CONFIG_OABI_COMPAT)
 384
 385         /*
 386          * If we have CONFIG_OABI_COMPAT then we need to look at the swi
 387          * value to determine if it is an EABI or an old ABI call.
 388          */
 389 #ifdef CONFIG_ARM_THUMB
 390         tst     r8, #PSR_T_BIT
 391         movne   r10, #0                         @ no thumb OABI emulation
 392  USER(  ldreq   r10, [lr, #-4]          )       @ get SWI instruction
 393 #else
 394  USER(  ldr     r10, [lr, #-4]          )       @ get SWI instruction
 395 #endif
 396  ARM_BE8(rev    r10, r10)                       @ little endian instruction
 397
 398 #elif defined(CONFIG_AEABI)
 399
 400         /*
 401          * Pure EABI user space always put syscall number into scno (r7).
 402          */
 403 #elif defined(CONFIG_ARM_THUMB)
 404         /* Legacy ABI only, possibly thumb mode. */
 405         tst     r8, #PSR_T_BIT                  @ this is SPSR from save_user_regs
 406         addne   scno, r7, #__NR_SYSCALL_BASE    @ put OS number in
 407  USER(  ldreq   scno, [lr, #-4]         )
 408
 409 #else
 410         /* Legacy ABI only. */
 411  USER(  ldr     scno, [lr, #-4]         )       @ get SWI instruction
 412 #endif
 413
 414         adr     tbl, sys_call_table             @ load syscall table pointer
 415
 416 #if defined(CONFIG_OABI_COMPAT)
 417         /*
 418          * If the swi argument is zero, this is an EABI call and we do nothing.
 419          *
 420          * If this is an old ABI call, get the syscall number into scno and
 421          * get the old ABI syscall table address.
 422          */
 423         bics    r10, r10, #0xff000000
 424         eorne   scno, r10, #__NR_OABI_SYSCALL_BASE
 425         ldrne   tbl, =sys_oabi_call_table
 426 #elif !defined(CONFIG_AEABI)
 427         bic     scno, scno, #0xff000000         @ mask off SWI op-code
 428         eor     scno, scno, #__NR_SYSCALL_BASE  @ check OS number
 429 #endif
 430
 431 local_restart:
 432         ldr     r10, [tsk, #TI_FLAGS]           @ check for syscall tracing
 433         stmdb   sp!, {r4, r5}                   @ push fifth and sixth args
 434
 435         tst     r10, #_TIF_SYSCALL_WORK         @ are we tracing syscalls?
 436         bne     __sys_trace
 437
 438         cmp     scno, #NR_syscalls              @ check upper syscall limit
 439         adr     lr, BSYM(ret_fast_syscall)      @ return address
 440         ldrcc   pc, [tbl, scno, lsl #2]         @ call sys_* routine
 441
 442         add     r1, sp, #S_OFF
 443 2:      cmp     scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
 444         eor     r0, scno, #__NR_SYSCALL_BASE    @ put OS number back
 445         bcs     arm_syscall
 446         mov     why, #0                         @ no longer a real syscall
 447         b       sys_ni_syscall                  @ not private func
 448
 449 #if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI)
 450         /*
 451          * We failed to handle a fault trying to access the page
 452          * containing the swi instruction, but we're not really in a
 453          * position to return -EFAULT. Instead, return back to the
 454          * instruction and re-enter the user fault handling path trying
 455          * to page it in. This will likely result in sending SEGV to the
 456          * current task.
 457          */
 458 9001:
 459         sub     lr, lr, #4
 460         str     lr, [sp, #S_PC]
 461         b       ret_fast_syscall
 462 #endif
 463 ENDPROC(vector_swi)
 464
 465         /*
 466          * This is the really slow path.  We're going to be doing
 467          * context switches, and waiting for our parent to respond.
 468          */
 469 __sys_trace:
 470         mov     r1, scno
 471         add     r0, sp, #S_OFF
 472         bl      syscall_trace_enter
 473
 474         adr     lr, BSYM(__sys_trace_return)    @ return address
 475         mov     scno, r0                        @ syscall number (possibly new)
 476         add     r1, sp, #S_R0 + S_OFF           @ pointer to regs
 477         cmp     scno, #NR_syscalls              @ check upper syscall limit
 478         ldmccia r1, {r0 - r6}                   @ have to reload r0 - r6
 479         stmccia sp, {r4, r5}                    @ and update the stack args
 480         ldrcc   pc, [tbl, scno, lsl #2]         @ call sys_* routine
 481         cmp     scno, #-1                       @ skip the syscall?
 482         bne     2b
 483         add     sp, sp, #S_OFF                  @ restore stack
 484         b       ret_slow_syscall
 485
 486 __sys_trace_return:
 487         str     r0, [sp, #S_R0 + S_OFF]!        @ save returned r0
 488         mov     r0, sp
 489         bl      syscall_trace_exit
 490         b       ret_slow_syscall
 491
 492         .align  5
 493 #ifdef CONFIG_ALIGNMENT_TRAP
 494         .type   __cr_alignment, #object
 495 __cr_alignment:
 496         .word   cr_alignment
 497 #endif
 498         .ltorg
 499
 500 /*
 501  * This is the syscall table declaration for native ABI syscalls.
 502  * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
 503  */
 504 #define ABI(native, compat) native
 505 #ifdef CONFIG_AEABI
 506 #define OBSOLETE(syscall) sys_ni_syscall
 507 #else
 508 #define OBSOLETE(syscall) syscall
 509 #endif
 510
 511         .type   sys_call_table, #object
 512 ENTRY(sys_call_table)
 513 #include "calls.S"
 514 #undef ABI
 515 #undef OBSOLETE
 516
 517 /*============================================================================
 518  * Special system call wrappers
 519  */
 520 @ r0 = syscall number
 521 @ r8 = syscall table
 522 sys_syscall:
 523                 bic     scno, r0, #__NR_OABI_SYSCALL_BASE
 524                 cmp     scno, #__NR_syscall - __NR_SYSCALL_BASE
 525                 cmpne   scno, #NR_syscalls      @ check range
 526                 stmloia sp, {r5, r6}            @ shuffle args
 527                 movlo   r0, r1
 528                 movlo   r1, r2
 529                 movlo   r2, r3
 530                 movlo   r3, r4
 531                 ldrlo   pc, [tbl, scno, lsl #2]
 532                 b       sys_ni_syscall
 533 ENDPROC(sys_syscall)
 534
 535 sys_sigreturn_wrapper:
 536                 add     r0, sp, #S_OFF
 537                 mov     why, #0         @ prevent syscall restart handling
 538                 b       sys_sigreturn
 539 ENDPROC(sys_sigreturn_wrapper)
 540
 541 sys_rt_sigreturn_wrapper:
 542                 add     r0, sp, #S_OFF
 543                 mov     why, #0         @ prevent syscall restart handling
 544                 b       sys_rt_sigreturn
 545 ENDPROC(sys_rt_sigreturn_wrapper)
 546
 547 sys_statfs64_wrapper:
 548                 teq     r1, #88
 549                 moveq   r1, #84
 550                 b       sys_statfs64
 551 ENDPROC(sys_statfs64_wrapper)
 552
 553 sys_fstatfs64_wrapper:
 554                 teq     r1, #88
 555                 moveq   r1, #84
 556                 b       sys_fstatfs64
 557 ENDPROC(sys_fstatfs64_wrapper)
 558
 559 /*
 560  * Note: off_4k (r5) is always units of 4K.  If we can't do the requested
 561  * offset, we return EINVAL.
 562  */
 563 sys_mmap2:
 564 #if PAGE_SHIFT > 12
 565                 tst     r5, #PGOFF_MASK
 566                 moveq   r5, r5, lsr #PAGE_SHIFT - 12
 567                 streq   r5, [sp, #4]
 568                 beq     sys_mmap_pgoff
 569                 mov     r0, #-EINVAL
 570                 mov     pc, lr
 571 #else
 572                 str     r5, [sp, #4]
 573                 b       sys_mmap_pgoff
 574 #endif
 575 ENDPROC(sys_mmap2)
 576
 577 #ifdef CONFIG_OABI_COMPAT
 578
 579 /*
 580  * These are syscalls with argument register differences
 581  */
 582
 583 sys_oabi_pread64:
 584                 stmia   sp, {r3, r4}
 585                 b       sys_pread64
 586 ENDPROC(sys_oabi_pread64)
 587
 588 sys_oabi_pwrite64:
 589                 stmia   sp, {r3, r4}
 590                 b       sys_pwrite64
 591 ENDPROC(sys_oabi_pwrite64)
 592
 593 sys_oabi_truncate64:
 594                 mov     r3, r2
 595                 mov     r2, r1
 596                 b       sys_truncate64
 597 ENDPROC(sys_oabi_truncate64)
 598
 599 sys_oabi_ftruncate64:
 600                 mov     r3, r2
 601                 mov     r2, r1
 602                 b       sys_ftruncate64
 603 ENDPROC(sys_oabi_ftruncate64)
 604
 605 sys_oabi_readahead:
 606                 str     r3, [sp]
 607                 mov     r3, r2
 608                 mov     r2, r1
 609                 b       sys_readahead
 610 ENDPROC(sys_oabi_readahead)
 611
 612 /*
 613  * Let's declare a second syscall table for old ABI binaries
 614  * using the compatibility syscall entries.
 615  */
 616 #define ABI(native, compat) compat
 617 #define OBSOLETE(syscall) syscall
 618
 619         .type   sys_oabi_call_table, #object
 620 ENTRY(sys_oabi_call_table)
 621 #include "calls.S"
 622 #undef ABI
 623 #undef OBSOLETE
 624
 625 #endif
 626