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 #if defined(CONFIG_IRQSOFF_TRACER)
  39         asm_trace_hardirqs_on
  40 #endif
  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
  48 /*
  49  * Ok, we need to do extra processing, enter the slow path.
  50  */
  51 fast_work_pending:
  52         str     r0, [sp, #S_R0+S_OFF]!          @ returned r0
  53 work_pending:
  54         mov     r0, sp                          @ 'regs'
  55         mov     r2, why                         @ 'syscall'
  56         bl      do_work_pending
  57         cmp     r0, #0
  58         beq     no_work_pending
  59         movlt   scno, #(__NR_restart_syscall - __NR_SYSCALL_BASE)
  60         ldmia   sp, {r0 - r6}                   @ have to reload r0 - r6
  61         b       local_restart                   @ ... and off we go
  62
  63 /*
  64  * "slow" syscall return path.  "why" tells us if this was a real syscall.
  65  */
  66 ENTRY(ret_to_user)
  67 ret_slow_syscall:
  68         disable_irq                             @ disable interrupts
  69 ENTRY(ret_to_user_from_irq)
  70         ldr     r1, [tsk, #TI_FLAGS]
  71         tst     r1, #_TIF_WORK_MASK
  72         bne     work_pending
  73 no_work_pending:
  74 #if defined(CONFIG_IRQSOFF_TRACER)
  75         asm_trace_hardirqs_on
  76 #endif
  77         /* perform architecture specific actions before user return */
  78         arch_ret_to_user r1, lr
  79
  80         restore_user_regs fast = 0, offset = 0
  81 ENDPROC(ret_to_user_from_irq)
  82 ENDPROC(ret_to_user)
  83
  84 /*
  85  * This is how we return from a fork.
  86  */
  87 ENTRY(ret_from_fork)
  88         bl      schedule_tail
  89         get_thread_info tsk
  90         mov     why, #1
  91         b       ret_slow_syscall
  92 ENDPROC(ret_from_fork)
  93
  94 ENTRY(ret_from_kernel_thread)
  95  UNWIND(.fnstart)
  96  UNWIND(.cantunwind)
  97         bl      schedule_tail
  98         mov     r0, r4
  99         adr     lr, BSYM(1f)    @ kernel threads should not exit
 100         mov     pc, r5
 101 1:      bl      do_exit
 102         nop
 103  UNWIND(.fnend)
 104 ENDPROC(ret_from_kernel_thread)
 105
 106 /*
 107  * turn a kernel thread into userland process
 108  * use: ret_from_kernel_execve(struct pt_regs *normal)
 109  */
 110 ENTRY(ret_from_kernel_execve)
 111         mov     why, #0                 @ not a syscall
 112         str     why, [r0, #S_R0]        @ ... and we want 0 in ->ARM_r0 as well
 113         get_thread_info tsk             @ thread structure
 114         mov     sp, r0                  @ stack pointer just under pt_regs
 115         b       ret_slow_syscall
 116 ENDPROC(ret_from_kernel_execve)
 117
 118         .equ NR_syscalls,0
 119 #define CALL(x) .equ NR_syscalls,NR_syscalls+1
 120 #include "calls.S"
 121 #undef CALL
 122 #define CALL(x) .long x
 123
 124 #ifdef CONFIG_FUNCTION_TRACER
 125 /*
 126  * When compiling with -pg, gcc inserts a call to the mcount routine at the
 127  * start of every function.  In mcount, apart from the function's address (in
 128  * lr), we need to get hold of the function's caller's address.
 129  *
 130  * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:
 131  *
 132  *      bl      mcount
 133  *
 134  * These versions have the limitation that in order for the mcount routine to
 135  * be able to determine the function's caller's address, an APCS-style frame
 136  * pointer (which is set up with something like the code below) is required.
 137  *
 138  *      mov     ip, sp
 139  *      push    {fp, ip, lr, pc}
 140  *      sub     fp, ip, #4
 141  *
 142  * With EABI, these frame pointers are not available unless -mapcs-frame is
 143  * specified, and if building as Thumb-2, not even then.
 144  *
 145  * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,
 146  * with call sites like:
 147  *
 148  *      push    {lr}
 149  *      bl      __gnu_mcount_nc
 150  *
 151  * With these compilers, frame pointers are not necessary.
 152  *
 153  * mcount can be thought of as a function called in the middle of a subroutine
 154  * call.  As such, it needs to be transparent for both the caller and the
 155  * callee: the original lr needs to be restored when leaving mcount, and no
 156  * registers should be clobbered.  (In the __gnu_mcount_nc implementation, we
 157  * clobber the ip register.  This is OK because the ARM calling convention
 158  * allows it to be clobbered in subroutines and doesn't use it to hold
 159  * parameters.)
 160  *
 161  * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
 162  * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
 163  * arch/arm/kernel/ftrace.c).
 164  */
 165
 166 #ifndef CONFIG_OLD_MCOUNT
 167 #if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
 168 #error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
 169 #endif
 170 #endif
 171
 172 .macro mcount_adjust_addr rd, rn
 173         bic     \rd, \rn, #1            @ clear the Thumb bit if present
 174         sub     \rd, \rd, #MCOUNT_INSN_SIZE
 175 .endm
 176
 177 .macro __mcount suffix
 178         mcount_enter
 179         ldr     r0, =ftrace_trace_function
 180         ldr     r2, [r0]
 181         adr     r0, .Lftrace_stub
 182         cmp     r0, r2
 183         bne     1f
 184
 185 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 186         ldr     r1, =ftrace_graph_return
 187         ldr     r2, [r1]
 188         cmp     r0, r2
 189         bne     ftrace_graph_caller\suffix
 190
 191         ldr     r1, =ftrace_graph_entry
 192         ldr     r2, [r1]
 193         ldr     r0, =ftrace_graph_entry_stub
 194         cmp     r0, r2
 195         bne     ftrace_graph_caller\suffix
 196 #endif
 197
 198         mcount_exit
 199
 200 1:      mcount_get_lr   r1                      @ lr of instrumented func
 201         mcount_adjust_addr      r0, lr          @ instrumented function
 202         adr     lr, BSYM(2f)
 203         mov     pc, r2
 204 2:      mcount_exit
 205 .endm
 206
 207 .macro __ftrace_caller suffix
 208         mcount_enter
 209
 210         mcount_get_lr   r1                      @ lr of instrumented func
 211         mcount_adjust_addr      r0, lr          @ instrumented function
 212
 213         .globl ftrace_call\suffix
 214 ftrace_call\suffix:
 215         bl      ftrace_stub
 216
 217 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 218         .globl ftrace_graph_call\suffix
 219 ftrace_graph_call\suffix:
 220         mov     r0, r0
 221 #endif
 222
 223         mcount_exit
 224 .endm
 225
 226 .macro __ftrace_graph_caller
 227         sub     r0, fp, #4              @ &lr of instrumented routine (&parent)
 228 #ifdef CONFIG_DYNAMIC_FTRACE
 229         @ called from __ftrace_caller, saved in mcount_enter
 230         ldr     r1, [sp, #16]           @ instrumented routine (func)
 231         mcount_adjust_addr      r1, r1
 232 #else
 233         @ called from __mcount, untouched in lr
 234         mcount_adjust_addr      r1, lr  @ instrumented routine (func)
 235 #endif
 236         mov     r2, fp                  @ frame pointer
 237         bl      prepare_ftrace_return
 238         mcount_exit
 239 .endm
 240
 241 #ifdef CONFIG_OLD_MCOUNT
 242 /*
 243  * mcount
 244  */
 245
 246 .macro mcount_enter
 247         stmdb   sp!, {r0-r3, lr}
 248 .endm
 249
 250 .macro mcount_get_lr reg
 251         ldr     \reg, [fp, #-4]
 252 .endm
 253
 254 .macro mcount_exit
 255         ldr     lr, [fp, #-4]
 256         ldmia   sp!, {r0-r3, pc}
 257 .endm
 258
 259 ENTRY(mcount)
 260 #ifdef CONFIG_DYNAMIC_FTRACE
 261         stmdb   sp!, {lr}
 262         ldr     lr, [fp, #-4]
 263         ldmia   sp!, {pc}
 264 #else
 265         __mcount _old
 266 #endif
 267 ENDPROC(mcount)
 268
 269 #ifdef CONFIG_DYNAMIC_FTRACE
 270 ENTRY(ftrace_caller_old)
 271         __ftrace_caller _old
 272 ENDPROC(ftrace_caller_old)
 273 #endif
 274
 275 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 276 ENTRY(ftrace_graph_caller_old)
 277         __ftrace_graph_caller
 278 ENDPROC(ftrace_graph_caller_old)
 279 #endif
 280
 281 .purgem mcount_enter
 282 .purgem mcount_get_lr
 283 .purgem mcount_exit
 284 #endif
 285
 286 /*
 287  * __gnu_mcount_nc
 288  */
 289
 290 .macro mcount_enter
 291         stmdb   sp!, {r0-r3, lr}
 292 .endm
 293
 294 .macro mcount_get_lr reg
 295         ldr     \reg, [sp, #20]
 296 .endm
 297
 298 .macro mcount_exit
 299         ldmia   sp!, {r0-r3, ip, lr}
 300         mov     pc, ip
 301 .endm
 302
 303 ENTRY(__gnu_mcount_nc)
 304 #ifdef CONFIG_DYNAMIC_FTRACE
 305         mov     ip, lr
 306         ldmia   sp!, {lr}
 307         mov     pc, ip
 308 #else
 309         __mcount
 310 #endif
 311 ENDPROC(__gnu_mcount_nc)
 312
 313 #ifdef CONFIG_DYNAMIC_FTRACE
 314 ENTRY(ftrace_caller)
 315         __ftrace_caller
 316 ENDPROC(ftrace_caller)
 317 #endif
 318
 319 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 320 ENTRY(ftrace_graph_caller)
 321         __ftrace_graph_caller
 322 ENDPROC(ftrace_graph_caller)
 323 #endif
 324
 325 .purgem mcount_enter
 326 .purgem mcount_get_lr
 327 .purgem mcount_exit
 328
 329 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 330         .globl return_to_handler
 331 return_to_handler:
 332         stmdb   sp!, {r0-r3}
 333         mov     r0, fp                  @ frame pointer
 334         bl      ftrace_return_to_handler
 335         mov     lr, r0                  @ r0 has real ret addr
 336         ldmia   sp!, {r0-r3}
 337         mov     pc, lr
 338 #endif
 339
 340 ENTRY(ftrace_stub)
 341 .Lftrace_stub:
 342         mov     pc, lr
 343 ENDPROC(ftrace_stub)
 344
 345 #endif /* CONFIG_FUNCTION_TRACER */
 346
 347 /*=============================================================================
 348  * SWI handler
 349  *-----------------------------------------------------------------------------
 350  */
 351
 352         .align  5
 353 ENTRY(vector_swi)
 354         sub     sp, sp, #S_FRAME_SIZE
 355         stmia   sp, {r0 - r12}                  @ Calling r0 - r12
 356  ARM(   add     r8, sp, #S_PC           )
 357  ARM(   stmdb   r8, {sp, lr}^           )       @ Calling sp, lr
 358  THUMB( mov     r8, sp                  )
 359  THUMB( store_user_sp_lr r8, r10, S_SP  )       @ calling sp, lr
 360         mrs     r8, spsr                        @ called from non-FIQ mode, so ok.
 361         str     lr, [sp, #S_PC]                 @ Save calling PC
 362         str     r8, [sp, #S_PSR]                @ Save CPSR
 363         str     r0, [sp, #S_OLD_R0]             @ Save OLD_R0
 364         zero_fp
 365
 366         /*
 367          * Get the system call number.
 368          */
 369
 370 #if defined(CONFIG_OABI_COMPAT)
 371
 372         /*
 373          * If we have CONFIG_OABI_COMPAT then we need to look at the swi
 374          * value to determine if it is an EABI or an old ABI call.
 375          */
 376 #ifdef CONFIG_ARM_THUMB
 377         tst     r8, #PSR_T_BIT
 378         movne   r10, #0                         @ no thumb OABI emulation
 379         ldreq   r10, [lr, #-4]                  @ get SWI instruction
 380 #else
 381         ldr     r10, [lr, #-4]                  @ get SWI instruction
 382 #endif
 383 #ifdef CONFIG_CPU_ENDIAN_BE8
 384         rev     r10, r10                        @ little endian instruction
 385 #endif
 386
 387 #elif defined(CONFIG_AEABI)
 388
 389         /*
 390          * Pure EABI user space always put syscall number into scno (r7).
 391          */
 392 #elif defined(CONFIG_ARM_THUMB)
 393         /* Legacy ABI only, possibly thumb mode. */
 394         tst     r8, #PSR_T_BIT                  @ this is SPSR from save_user_regs
 395         addne   scno, r7, #__NR_SYSCALL_BASE    @ put OS number in
 396         ldreq   scno, [lr, #-4]
 397
 398 #else
 399         /* Legacy ABI only. */
 400         ldr     scno, [lr, #-4]                 @ get SWI instruction
 401 #endif
 402
 403 #ifdef CONFIG_ALIGNMENT_TRAP
 404         ldr     ip, __cr_alignment
 405         ldr     ip, [ip]
 406         mcr     p15, 0, ip, c1, c0              @ update control register
 407 #endif
 408         enable_irq
 409
 410         get_thread_info tsk
 411         adr     tbl, sys_call_table             @ load syscall table pointer
 412
 413 #if defined(CONFIG_OABI_COMPAT)
 414         /*
 415          * If the swi argument is zero, this is an EABI call and we do nothing.
 416          *
 417          * If this is an old ABI call, get the syscall number into scno and
 418          * get the old ABI syscall table address.
 419          */
 420         bics    r10, r10, #0xff000000
 421         eorne   scno, r10, #__NR_OABI_SYSCALL_BASE
 422         ldrne   tbl, =sys_oabi_call_table
 423 #elif !defined(CONFIG_AEABI)
 424         bic     scno, scno, #0xff000000         @ mask off SWI op-code
 425         eor     scno, scno, #__NR_SYSCALL_BASE  @ check OS number
 426 #endif
 427
 428 local_restart:
 429         ldr     r10, [tsk, #TI_FLAGS]           @ check for syscall tracing
 430         stmdb   sp!, {r4, r5}                   @ push fifth and sixth args
 431
 432 #ifdef CONFIG_SECCOMP
 433         tst     r10, #_TIF_SECCOMP
 434         beq     1f
 435         mov     r0, scno
 436         bl      __secure_computing
 437         add     r0, sp, #S_R0 + S_OFF           @ pointer to regs
 438         ldmia   r0, {r0 - r3}                   @ have to reload r0 - r3
 439 1:
 440 #endif
 441
 442         tst     r10, #_TIF_SYSCALL_WORK         @ are we tracing syscalls?
 443         bne     __sys_trace
 444
 445         cmp     scno, #NR_syscalls              @ check upper syscall limit
 446         adr     lr, BSYM(ret_fast_syscall)      @ return address
 447         ldrcc   pc, [tbl, scno, lsl #2]         @ call sys_* routine
 448
 449         add     r1, sp, #S_OFF
 450 2:      mov     why, #0                         @ no longer a real syscall
 451         cmp     scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
 452         eor     r0, scno, #__NR_SYSCALL_BASE    @ put OS number back
 453         bcs     arm_syscall
 454         b       sys_ni_syscall                  @ not private func
 455 ENDPROC(vector_swi)
 456
 457         /*
 458          * This is the really slow path.  We're going to be doing
 459          * context switches, and waiting for our parent to respond.
 460          */
 461 __sys_trace:
 462         mov     r1, scno
 463         add     r0, sp, #S_OFF
 464         bl      syscall_trace_enter
 465
 466         adr     lr, BSYM(__sys_trace_return)    @ return address
 467         mov     scno, r0                        @ syscall number (possibly new)
 468         add     r1, sp, #S_R0 + S_OFF           @ pointer to regs
 469         cmp     scno, #NR_syscalls              @ check upper syscall limit
 470         ldmccia r1, {r0 - r6}                   @ have to reload r0 - r6
 471         stmccia sp, {r4, r5}                    @ and update the stack args
 472         ldrcc   pc, [tbl, scno, lsl #2]         @ call sys_* routine
 473         b       2b
 474
 475 __sys_trace_return:
 476         str     r0, [sp, #S_R0 + S_OFF]!        @ save returned r0
 477         mov     r1, scno
 478         mov     r0, sp
 479         bl      syscall_trace_exit
 480         b       ret_slow_syscall
 481
 482         .align  5
 483 #ifdef CONFIG_ALIGNMENT_TRAP
 484         .type   __cr_alignment, #object
 485 __cr_alignment:
 486         .word   cr_alignment
 487 #endif
 488         .ltorg
 489
 490 /*
 491  * This is the syscall table declaration for native ABI syscalls.
 492  * With EABI a couple syscalls are obsolete and defined as sys_ni_syscall.
 493  */
 494 #define ABI(native, compat) native
 495 #ifdef CONFIG_AEABI
 496 #define OBSOLETE(syscall) sys_ni_syscall
 497 #else
 498 #define OBSOLETE(syscall) syscall
 499 #endif
 500
 501         .type   sys_call_table, #object
 502 ENTRY(sys_call_table)
 503 #include "calls.S"
 504 #undef ABI
 505 #undef OBSOLETE
 506
 507 /*============================================================================
 508  * Special system call wrappers
 509  */
 510 @ r0 = syscall number
 511 @ r8 = syscall table
 512 sys_syscall:
 513                 bic     scno, r0, #__NR_OABI_SYSCALL_BASE
 514                 cmp     scno, #__NR_syscall - __NR_SYSCALL_BASE
 515                 cmpne   scno, #NR_syscalls      @ check range
 516                 stmloia sp, {r5, r6}            @ shuffle args
 517                 movlo   r0, r1
 518                 movlo   r1, r2
 519                 movlo   r2, r3
 520                 movlo   r3, r4
 521                 ldrlo   pc, [tbl, scno, lsl #2]
 522                 b       sys_ni_syscall
 523 ENDPROC(sys_syscall)
 524
 525 sys_fork_wrapper:
 526                 add     r0, sp, #S_OFF
 527                 b       sys_fork
 528 ENDPROC(sys_fork_wrapper)
 529
 530 sys_vfork_wrapper:
 531                 add     r0, sp, #S_OFF
 532                 b       sys_vfork
 533 ENDPROC(sys_vfork_wrapper)
 534
 535 sys_clone_wrapper:
 536                 add     ip, sp, #S_OFF
 537                 str     ip, [sp, #4]
 538                 b       sys_clone
 539 ENDPROC(sys_clone_wrapper)
 540
 541 sys_sigreturn_wrapper:
 542                 add     r0, sp, #S_OFF
 543                 mov     why, #0         @ prevent syscall restart handling
 544                 b       sys_sigreturn
 545 ENDPROC(sys_sigreturn_wrapper)
 546
 547 sys_rt_sigreturn_wrapper:
 548                 add     r0, sp, #S_OFF
 549                 mov     why, #0         @ prevent syscall restart handling
 550                 b       sys_rt_sigreturn
 551 ENDPROC(sys_rt_sigreturn_wrapper)
 552
 553 sys_sigaltstack_wrapper:
 554                 ldr     r2, [sp, #S_OFF + S_SP]
 555                 b       do_sigaltstack
 556 ENDPROC(sys_sigaltstack_wrapper)
 557
 558 sys_statfs64_wrapper:
 559                 teq     r1, #88
 560                 moveq   r1, #84
 561                 b       sys_statfs64
 562 ENDPROC(sys_statfs64_wrapper)
 563
 564 sys_fstatfs64_wrapper:
 565                 teq     r1, #88
 566                 moveq   r1, #84
 567                 b       sys_fstatfs64
 568 ENDPROC(sys_fstatfs64_wrapper)
 569
 570 /*
 571  * Note: off_4k (r5) is always units of 4K.  If we can't do the requested
 572  * offset, we return EINVAL.
 573  */
 574 sys_mmap2:
 575 #if PAGE_SHIFT > 12
 576                 tst     r5, #PGOFF_MASK
 577                 moveq   r5, r5, lsr #PAGE_SHIFT - 12
 578                 streq   r5, [sp, #4]
 579                 beq     sys_mmap_pgoff
 580                 mov     r0, #-EINVAL
 581                 mov     pc, lr
 582 #else
 583                 str     r5, [sp, #4]
 584                 b       sys_mmap_pgoff
 585 #endif
 586 ENDPROC(sys_mmap2)
 587
 588 #ifdef CONFIG_OABI_COMPAT
 589
 590 /*
 591  * These are syscalls with argument register differences
 592  */
 593
 594 sys_oabi_pread64:
 595                 stmia   sp, {r3, r4}
 596                 b       sys_pread64
 597 ENDPROC(sys_oabi_pread64)
 598
 599 sys_oabi_pwrite64:
 600                 stmia   sp, {r3, r4}
 601                 b       sys_pwrite64
 602 ENDPROC(sys_oabi_pwrite64)
 603
 604 sys_oabi_truncate64:
 605                 mov     r3, r2
 606                 mov     r2, r1
 607                 b       sys_truncate64
 608 ENDPROC(sys_oabi_truncate64)
 609
 610 sys_oabi_ftruncate64:
 611                 mov     r3, r2
 612                 mov     r2, r1
 613                 b       sys_ftruncate64
 614 ENDPROC(sys_oabi_ftruncate64)
 615
 616 sys_oabi_readahead:
 617                 str     r3, [sp]
 618                 mov     r3, r2
 619                 mov     r2, r1
 620                 b       sys_readahead
 621 ENDPROC(sys_oabi_readahead)
 622
 623 /*
 624  * Let's declare a second syscall table for old ABI binaries
 625  * using the compatibility syscall entries.
 626  */
 627 #define ABI(native, compat) compat
 628 #define OBSOLETE(syscall) syscall
 629
 630         .type   sys_oabi_call_table, #object
 631 ENTRY(sys_oabi_call_table)
 632 #include "calls.S"
 633 #undef ABI
 634 #undef OBSOLETE
 635
 636 #endif
 637