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   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 #include <linux/config.h>
  11
  12 #include <asm/unistd.h>
  13
  14 #include "entry-header.S"
  15
  16
  17         .align  5
  18 /*
  19  * This is the fast syscall return path.  We do as little as
  20  * possible here, and this includes saving r0 back into the SVC
  21  * stack.
  22  */
  23 ret_fast_syscall:
  24         disable_irq                             @ disable interrupts
  25         ldr     r1, [tsk, #TI_FLAGS]
  26         tst     r1, #_TIF_WORK_MASK
  27         bne     fast_work_pending
  28
  29         @ fast_restore_user_regs
  30         ldr     r1, [sp, #S_OFF + S_PSR]        @ get calling cpsr
  31         ldr     lr, [sp, #S_OFF + S_PC]!        @ get pc
  32         msr     spsr_cxsf, r1                   @ save in spsr_svc
  33         ldmdb   sp, {r1 - lr}^                  @ get calling r1 - lr
  34         mov     r0, r0
  35         add     sp, sp, #S_FRAME_SIZE - S_PC
  36         movs    pc, lr                          @ return & move spsr_svc into cpsr
  37
  38 /*
  39  * Ok, we need to do extra processing, enter the slow path.
  40  */
  41 fast_work_pending:
  42         str     r0, [sp, #S_R0+S_OFF]!          @ returned r0
  43 work_pending:
  44         tst     r1, #_TIF_NEED_RESCHED
  45         bne     work_resched
  46         tst     r1, #_TIF_NOTIFY_RESUME | _TIF_SIGPENDING
  47         beq     no_work_pending
  48         mov     r0, sp                          @ 'regs'
  49         mov     r2, why                         @ 'syscall'
  50         bl      do_notify_resume
  51         b       ret_slow_syscall                @ Check work again
  52
  53 work_resched:
  54         bl      schedule
  55 /*
  56  * "slow" syscall return path.  "why" tells us if this was a real syscall.
  57  */
  58 ENTRY(ret_to_user)
  59 ret_slow_syscall:
  60         disable_irq                             @ disable interrupts
  61         ldr     r1, [tsk, #TI_FLAGS]
  62         tst     r1, #_TIF_WORK_MASK
  63         bne     work_pending
  64 no_work_pending:
  65         @ slow_restore_user_regs
  66         ldr     r1, [sp, #S_PSR]                @ get calling cpsr
  67         ldr     lr, [sp, #S_PC]!                @ get pc
  68         msr     spsr_cxsf, r1                   @ save in spsr_svc
  69         ldmdb   sp, {r0 - lr}^                  @ get calling r1 - lr
  70         mov     r0, r0
  71         add     sp, sp, #S_FRAME_SIZE - S_PC
  72         movs    pc, lr                          @ return & move spsr_svc into cpsr
  73
  74 /*
  75  * This is how we return from a fork.
  76  */
  77 ENTRY(ret_from_fork)
  78         bl      schedule_tail
  79         get_thread_info tsk
  80         ldr     r1, [tsk, #TI_FLAGS]            @ check for syscall tracing
  81         mov     why, #1
  82         tst     r1, #_TIF_SYSCALL_TRACE         @ are we tracing syscalls?
  83         beq     ret_slow_syscall
  84         mov     r1, sp
  85         mov     r0, #1                          @ trace exit [IP = 1]
  86         bl      syscall_trace
  87         b       ret_slow_syscall
  88
  89
  90 #include "calls.S"
  91
  92 /*=============================================================================
  93  * SWI handler
  94  *-----------------------------------------------------------------------------
  95  */
  96
  97         /* If we're optimising for StrongARM the resulting code won't
  98            run on an ARM7 and we can save a couple of instructions.
  99                                                                 --pb */
 100 #ifdef CONFIG_CPU_ARM710
 101 #define A710(code...) code
 102 .Larm710bug:
 103         ldmia   sp, {r0 - lr}^                  @ Get calling r0 - lr
 104         mov     r0, r0
 105         add     sp, sp, #S_FRAME_SIZE
 106         subs    pc, lr, #4
 107 #else
 108 #define A710(code...)
 109 #endif
 110
 111         .align  5
 112 ENTRY(vector_swi)
 113         sub     sp, sp, #S_FRAME_SIZE
 114         stmia   sp, {r0 - r12}                  @ Calling r0 - r12
 115         add     r8, sp, #S_PC
 116         stmdb   r8, {sp, lr}^                   @ Calling sp, lr
 117         mrs     r8, spsr                        @ called from non-FIQ mode, so ok.
 118         str     lr, [sp, #S_PC]                 @ Save calling PC
 119         str     r8, [sp, #S_PSR]                @ Save CPSR
 120         str     r0, [sp, #S_OLD_R0]             @ Save OLD_R0
 121         zero_fp
 122
 123         /*
 124          * Get the system call number.
 125          */
 126 #if defined(CONFIG_AEABI)
 127
 128         @ syscall number is in scno (r7) already.
 129
 130   A710( ldr     ip, [lr, #-4]                   @ get SWI instruction   )
 131   A710( and     ip, ip, #0x0f000000             @ check for SWI         )
 132   A710( teq     ip, #0x0f000000                                         )
 133   A710( bne     .Larm710bug                                             )
 134 #elif defined(CONFIG_ARM_THUMB)
 135         tst     r8, #PSR_T_BIT                  @ this is SPSR from save_user_regs
 136         addne   scno, r7, #__NR_SYSCALL_BASE    @ put OS number in
 137         ldreq   scno, [lr, #-4]
 138 #else
 139         ldr     scno, [lr, #-4]                 @ get SWI instruction
 140   A710( and     ip, scno, #0x0f000000           @ check for SWI         )
 141   A710( teq     ip, #0x0f000000                                         )
 142   A710( bne     .Larm710bug                                             )
 143 #endif
 144
 145 #ifdef CONFIG_ALIGNMENT_TRAP
 146         ldr     ip, __cr_alignment
 147         ldr     ip, [ip]
 148         mcr     p15, 0, ip, c1, c0              @ update control register
 149 #endif
 150         enable_irq
 151
 152         get_thread_info tsk
 153         ldr     ip, [tsk, #TI_FLAGS]            @ check for syscall tracing
 154 #ifndef CONFIG_AEABI
 155         bic     scno, scno, #0xff000000         @ mask off SWI op-code
 156         eor     scno, scno, #__NR_SYSCALL_BASE  @ check OS number
 157 #endif
 158         adr     tbl, sys_call_table             @ load syscall table pointer
 159         stmdb   sp!, {r4, r5}                   @ push fifth and sixth args
 160         tst     ip, #_TIF_SYSCALL_TRACE         @ are we tracing syscalls?
 161         bne     __sys_trace
 162
 163         cmp     scno, #NR_syscalls              @ check upper syscall limit
 164         adr     lr, ret_fast_syscall            @ return address
 165         ldrcc   pc, [tbl, scno, lsl #2]         @ call sys_* routine
 166
 167         add     r1, sp, #S_OFF
 168 2:      mov     why, #0                         @ no longer a real syscall
 169         cmp     scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
 170         eor     r0, scno, #__NR_SYSCALL_BASE    @ put OS number back
 171         bcs     arm_syscall
 172         b       sys_ni_syscall                  @ not private func
 173
 174         /*
 175          * This is the really slow path.  We're going to be doing
 176          * context switches, and waiting for our parent to respond.
 177          */
 178 __sys_trace:
 179         add     r1, sp, #S_OFF
 180         mov     r0, #0                          @ trace entry [IP = 0]
 181         bl      syscall_trace
 182
 183         adr     lr, __sys_trace_return          @ return address
 184         add     r1, sp, #S_R0 + S_OFF           @ pointer to regs
 185         cmp     scno, #NR_syscalls              @ check upper syscall limit
 186         ldmccia r1, {r0 - r3}                   @ have to reload r0 - r3
 187         ldrcc   pc, [tbl, scno, lsl #2]         @ call sys_* routine
 188         b       2b
 189
 190 __sys_trace_return:
 191         str     r0, [sp, #S_R0 + S_OFF]!        @ save returned r0
 192         mov     r1, sp
 193         mov     r0, #1                          @ trace exit [IP = 1]
 194         bl      syscall_trace
 195         b       ret_slow_syscall
 196
 197         .align  5
 198 #ifdef CONFIG_ALIGNMENT_TRAP
 199         .type   __cr_alignment, #object
 200 __cr_alignment:
 201         .word   cr_alignment
 202 #endif
 203
 204         .type   sys_call_table, #object
 205 ENTRY(sys_call_table)
 206 #include "calls.S"
 207
 208 /*============================================================================
 209  * Special system call wrappers
 210  */
 211 @ r0 = syscall number
 212 @ r8 = syscall table
 213                 .type   sys_syscall, #function
 214 sys_syscall:
 215 #ifndef CONFIG_AEABI
 216                 eor     scno, r0, #__NR_SYSCALL_BASE
 217                 cmp     scno, #__NR_syscall - __NR_SYSCALL_BASE
 218                 cmpne   scno, #NR_syscalls      @ check range
 219                 stmloia sp, {r5, r6}            @ shuffle args
 220                 movlo   r0, r1
 221                 movlo   r1, r2
 222                 movlo   r2, r3
 223                 movlo   r3, r4
 224                 ldrlo   pc, [tbl, scno, lsl #2]
 225 #endif
 226                 b       sys_ni_syscall
 227
 228 sys_fork_wrapper:
 229                 add     r0, sp, #S_OFF
 230                 b       sys_fork
 231
 232 sys_vfork_wrapper:
 233                 add     r0, sp, #S_OFF
 234                 b       sys_vfork
 235
 236 sys_execve_wrapper:
 237                 add     r3, sp, #S_OFF
 238                 b       sys_execve
 239
 240 sys_clone_wrapper:
 241                 add     ip, sp, #S_OFF
 242                 str     ip, [sp, #4]
 243                 b       sys_clone
 244
 245 sys_sigsuspend_wrapper:
 246                 add     r3, sp, #S_OFF
 247                 b       sys_sigsuspend
 248
 249 sys_rt_sigsuspend_wrapper:
 250                 add     r2, sp, #S_OFF
 251                 b       sys_rt_sigsuspend
 252
 253 sys_sigreturn_wrapper:
 254                 add     r0, sp, #S_OFF
 255                 b       sys_sigreturn
 256
 257 sys_rt_sigreturn_wrapper:
 258                 add     r0, sp, #S_OFF
 259                 b       sys_rt_sigreturn
 260
 261 sys_sigaltstack_wrapper:
 262                 ldr     r2, [sp, #S_OFF + S_SP]
 263                 b       do_sigaltstack
 264
 265 sys_statfs64_wrapper:
 266                 teq     r1, #88
 267                 moveq   r1, #84
 268                 b       sys_statfs64
 269
 270 sys_fstatfs64_wrapper:
 271                 teq     r1, #88
 272                 moveq   r1, #84
 273                 b       sys_fstatfs64
 274
 275 /*
 276  * Note: off_4k (r5) is always units of 4K.  If we can't do the requested
 277  * offset, we return EINVAL.
 278  */
 279 sys_mmap2:
 280 #if PAGE_SHIFT > 12
 281                 tst     r5, #PGOFF_MASK
 282                 moveq   r5, r5, lsr #PAGE_SHIFT - 12
 283                 streq   r5, [sp, #4]
 284                 beq     do_mmap2
 285                 mov     r0, #-EINVAL
 286                 RETINSTR(mov,pc, lr)
 287 #else
 288                 str     r5, [sp, #4]
 289                 b       do_mmap2
 290 #endif