LXR linux/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 */
  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