arch/ppc64/kernel/entry.S

   1 /*
   2  *  arch/ppc64/kernel/entry.S
   3  *
   4  *  PowerPC version
   5  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   6  *  Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP
   7  *    Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
   8  *  Adapted for Power Macintosh by Paul Mackerras.
   9  *  Low-level exception handlers and MMU support
  10  *  rewritten by Paul Mackerras.
  11  *    Copyright (C) 1996 Paul Mackerras.
  12  *  MPC8xx modifications Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
  13  *
  14  *  This file contains the system call entry code, context switch
  15  *  code, and exception/interrupt return code for PowerPC.
  16  *
  17  *  This program is free software; you can redistribute it and/or
  18  *  modify it under the terms of the GNU General Public License
  19  *  as published by the Free Software Foundation; either version
  20  *  2 of the License, or (at your option) any later version.
  21  */
  22
  23 #include <linux/config.h>
  24 #include <linux/errno.h>
  25 #include <asm/unistd.h>
  26 #include <asm/processor.h>
  27 #include <asm/page.h>
  28 #include <asm/mmu.h>
  29 #include <asm/thread_info.h>
  30 #include <asm/ppc_asm.h>
  31 #include <asm/offsets.h>
  32 #include <asm/cputable.h>
  33
  34 #ifdef CONFIG_PPC_ISERIES
  35 #define DO_SOFT_DISABLE
  36 #endif
  37
  38 /*
  39  * System calls.
  40  */
  41         .section        ".toc","aw"
  42 .SYS_CALL_TABLE:
  43         .tc .sys_call_table[TC],.sys_call_table
  44
  45 .SYS_CALL_TABLE32:
  46         .tc .sys_call_table32[TC],.sys_call_table32
  47
  48 /* This value is used to mark exception frames on the stack. */
  49 exception_marker:
  50         .tc     ID_72656773_68657265[TC],0x7265677368657265
  51
  52         .section        ".text"
  53         .align 7
  54
  55 #undef SHOW_SYSCALLS
  56
  57         .globl system_call_common
  58 system_call_common:
  59         andi.   r10,r12,MSR_PR
  60         mr      r10,r1
  61         addi    r1,r1,-INT_FRAME_SIZE
  62         beq-    1f
  63         ld      r1,PACAKSAVE(r13)
  64 1:      std     r10,0(r1)
  65         std     r11,_NIP(r1)
  66         std     r12,_MSR(r1)
  67         std     r0,GPR0(r1)
  68         std     r10,GPR1(r1)
  69         std     r2,GPR2(r1)
  70         std     r3,GPR3(r1)
  71         std     r4,GPR4(r1)
  72         std     r5,GPR5(r1)
  73         std     r6,GPR6(r1)
  74         std     r7,GPR7(r1)
  75         std     r8,GPR8(r1)
  76         li      r11,0
  77         std     r11,GPR9(r1)
  78         std     r11,GPR10(r1)
  79         std     r11,GPR11(r1)
  80         std     r11,GPR12(r1)
  81         std     r9,GPR13(r1)
  82         crclr   so
  83         mfcr    r9
  84         mflr    r10
  85         li      r11,0xc01
  86         std     r9,_CCR(r1)
  87         std     r10,_LINK(r1)
  88         std     r11,_TRAP(r1)
  89         mfxer   r9
  90         mfctr   r10
  91         std     r9,_XER(r1)
  92         std     r10,_CTR(r1)
  93         std     r3,ORIG_GPR3(r1)
  94         ld      r2,PACATOC(r13)
  95         addi    r9,r1,STACK_FRAME_OVERHEAD
  96         ld      r11,exception_marker@toc(r2)
  97         std     r11,-16(r9)             /* "regshere" marker */
  98 #ifdef CONFIG_PPC_ISERIES
  99         /* Hack for handling interrupts when soft-enabling on iSeries */
 100         cmpdi   cr1,r0,0x5555           /* syscall 0x5555 */
 101         andi.   r10,r12,MSR_PR          /* from kernel */
 102         crand   4*cr0+eq,4*cr1+eq,4*cr0+eq
 103         beq     hardware_interrupt_entry
 104         lbz     r10,PACAPROCENABLED(r13)
 105         std     r10,SOFTE(r1)
 106 #endif
 107         mfmsr   r11
 108         ori     r11,r11,MSR_EE
 109         mtmsrd  r11,1
 110
 111 #ifdef SHOW_SYSCALLS
 112         bl      .do_show_syscall
 113         REST_GPR(0,r1)
 114         REST_4GPRS(3,r1)
 115         REST_2GPRS(7,r1)
 116         addi    r9,r1,STACK_FRAME_OVERHEAD
 117 #endif
 118         clrrdi  r11,r1,THREAD_SHIFT
 119         li      r12,0
 120         ld      r10,TI_FLAGS(r11)
 121         stb     r12,TI_SC_NOERR(r11)
 122         andi.   r11,r10,_TIF_SYSCALL_T_OR_A
 123         bne-    syscall_dotrace
 124 syscall_dotrace_cont:
 125         cmpldi  0,r0,NR_syscalls
 126         bge-    syscall_enosys
 127
 128 system_call:                    /* label this so stack traces look sane */
 129 /*
 130  * Need to vector to 32 Bit or default sys_call_table here,
 131  * based on caller's run-mode / personality.
 132  */
 133         ld      r11,.SYS_CALL_TABLE@toc(2)
 134         andi.   r10,r10,_TIF_32BIT
 135         beq     15f
 136         ld      r11,.SYS_CALL_TABLE32@toc(2)
 137         clrldi  r3,r3,32
 138         clrldi  r4,r4,32
 139         clrldi  r5,r5,32
 140         clrldi  r6,r6,32
 141         clrldi  r7,r7,32
 142         clrldi  r8,r8,32
 143 15:
 144         slwi    r0,r0,3
 145         ldx     r10,r11,r0      /* Fetch system call handler [ptr] */
 146         mtctr   r10
 147         bctrl                   /* Call handler */
 148
 149 syscall_exit:
 150 #ifdef SHOW_SYSCALLS
 151         std     r3,GPR3(r1)
 152         bl      .do_show_syscall_exit
 153         ld      r3,GPR3(r1)
 154 #endif
 155         std     r3,RESULT(r1)
 156         ld      r5,_CCR(r1)
 157         li      r10,-_LAST_ERRNO
 158         cmpld   r3,r10
 159         clrrdi  r12,r1,THREAD_SHIFT
 160         bge-    syscall_error
 161 syscall_error_cont:
 162
 163         /* check for syscall tracing or audit */
 164         ld      r9,TI_FLAGS(r12)
 165         andi.   r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
 166         bne-    syscall_exit_trace
 167 syscall_exit_trace_cont:
 168
 169         /* disable interrupts so current_thread_info()->flags can't change,
 170            and so that we don't get interrupted after loading SRR0/1. */
 171         ld      r8,_MSR(r1)
 172         andi.   r10,r8,MSR_RI
 173         beq-    unrecov_restore
 174         mfmsr   r10
 175         rldicl  r10,r10,48,1
 176         rotldi  r10,r10,16
 177         mtmsrd  r10,1
 178         ld      r9,TI_FLAGS(r12)
 179         andi.   r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SIGPENDING|_TIF_NEED_RESCHED)
 180         bne-    syscall_exit_work
 181         ld      r7,_NIP(r1)
 182         stdcx.  r0,0,r1                 /* to clear the reservation */
 183         andi.   r6,r8,MSR_PR
 184         ld      r4,_LINK(r1)
 185         beq-    1f                      /* only restore r13 if */
 186         ld      r13,GPR13(r1)           /* returning to usermode */
 187 1:      ld      r2,GPR2(r1)
 188         li      r12,MSR_RI
 189         andc    r10,r10,r12
 190         mtmsrd  r10,1                   /* clear MSR.RI */
 191         ld      r1,GPR1(r1)
 192         mtlr    r4
 193         mtcr    r5
 194         mtspr   SRR0,r7
 195         mtspr   SRR1,r8
 196         rfid
 197         b       .       /* prevent speculative execution */
 198
 199 syscall_enosys:
 200         li      r3,-ENOSYS
 201         std     r3,RESULT(r1)
 202         clrrdi  r12,r1,THREAD_SHIFT
 203         ld      r5,_CCR(r1)
 204
 205 syscall_error:
 206         lbz     r11,TI_SC_NOERR(r12)
 207         cmpwi   0,r11,0
 208         bne-    syscall_error_cont
 209         neg     r3,r3
 210         oris    r5,r5,0x1000    /* Set SO bit in CR */
 211         std     r5,_CCR(r1)
 212         b       syscall_error_cont
 213
 214 /* Traced system call support */
 215 syscall_dotrace:
 216         bl      .save_nvgprs
 217         addi    r3,r1,STACK_FRAME_OVERHEAD
 218         bl      .do_syscall_trace_enter
 219         ld      r0,GPR0(r1)     /* Restore original registers */
 220         ld      r3,GPR3(r1)
 221         ld      r4,GPR4(r1)
 222         ld      r5,GPR5(r1)
 223         ld      r6,GPR6(r1)
 224         ld      r7,GPR7(r1)
 225         ld      r8,GPR8(r1)
 226         addi    r9,r1,STACK_FRAME_OVERHEAD
 227         clrrdi  r10,r1,THREAD_SHIFT
 228         ld      r10,TI_FLAGS(r10)
 229         b       syscall_dotrace_cont
 230
 231 syscall_exit_trace:
 232         std     r3,GPR3(r1)
 233         bl      .save_nvgprs
 234         addi    r3,r1,STACK_FRAME_OVERHEAD
 235         bl      .do_syscall_trace_leave
 236         REST_NVGPRS(r1)
 237         ld      r3,GPR3(r1)
 238         ld      r5,_CCR(r1)
 239         clrrdi  r12,r1,THREAD_SHIFT
 240         b       syscall_exit_trace_cont
 241
 242 /* Stuff to do on exit from a system call. */
 243 syscall_exit_work:
 244         std     r3,GPR3(r1)
 245         std     r5,_CCR(r1)
 246         b       .ret_from_except_lite
 247
 248 /* Save non-volatile GPRs, if not already saved. */
 249 _GLOBAL(save_nvgprs)
 250         ld      r11,_TRAP(r1)
 251         andi.   r0,r11,1
 252         beqlr-
 253         SAVE_NVGPRS(r1)
 254         clrrdi  r0,r11,1
 255         std     r0,_TRAP(r1)
 256         blr
 257
 258 /*
 259  * The sigsuspend and rt_sigsuspend system calls can call do_signal
 260  * and thus put the process into the stopped state where we might
 261  * want to examine its user state with ptrace.  Therefore we need
 262  * to save all the nonvolatile registers (r14 - r31) before calling
 263  * the C code.  Similarly, fork, vfork and clone need the full
 264  * register state on the stack so that it can be copied to the child.
 265  */
 266 _GLOBAL(ppc32_sigsuspend)
 267         bl      .save_nvgprs
 268         bl      .sys32_sigsuspend
 269         b       70f
 270
 271 _GLOBAL(ppc64_rt_sigsuspend)
 272         bl      .save_nvgprs
 273         bl      .sys_rt_sigsuspend
 274         b       70f
 275
 276 _GLOBAL(ppc32_rt_sigsuspend)
 277         bl      .save_nvgprs
 278         bl      .sys32_rt_sigsuspend
 279         /* If sigsuspend() returns zero, we are going into a signal handler */
 280 70:     cmpdi   0,r3,0
 281         beq     .ret_from_except
 282         /* If it returned -EINTR, we need to return via syscall_exit to set
 283            the SO bit in cr0 and potentially stop for ptrace. */
 284         b       syscall_exit
 285
 286 _GLOBAL(ppc_fork)
 287         bl      .save_nvgprs
 288         bl      .sys_fork
 289         b       syscall_exit
 290
 291 _GLOBAL(ppc_vfork)
 292         bl      .save_nvgprs
 293         bl      .sys_vfork
 294         b       syscall_exit
 295
 296 _GLOBAL(ppc_clone)
 297         bl      .save_nvgprs
 298         bl      .sys_clone
 299         b       syscall_exit
 300
 301 _GLOBAL(ppc32_swapcontext)
 302         bl      .save_nvgprs
 303         bl      .sys32_swapcontext
 304         b       80f
 305
 306 _GLOBAL(ppc64_swapcontext)
 307         bl      .save_nvgprs
 308         bl      .sys_swapcontext
 309         b       80f
 310
 311 _GLOBAL(ppc32_sigreturn)
 312         bl      .sys32_sigreturn
 313         b       80f
 314
 315 _GLOBAL(ppc32_rt_sigreturn)
 316         bl      .sys32_rt_sigreturn
 317         b       80f
 318
 319 _GLOBAL(ppc64_rt_sigreturn)
 320         bl      .sys_rt_sigreturn
 321
 322 80:     cmpdi   0,r3,0
 323         blt     syscall_exit
 324         clrrdi  r4,r1,THREAD_SHIFT
 325         ld      r4,TI_FLAGS(r4)
 326         andi.   r4,r4,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
 327         beq+    81f
 328         addi    r3,r1,STACK_FRAME_OVERHEAD
 329         bl      .do_syscall_trace_leave
 330 81:     b       .ret_from_except
 331
 332 _GLOBAL(ret_from_fork)
 333         bl      .schedule_tail
 334         REST_NVGPRS(r1)
 335         li      r3,0
 336         b       syscall_exit
 337
 338 /*
 339  * This routine switches between two different tasks.  The process
 340  * state of one is saved on its kernel stack.  Then the state
 341  * of the other is restored from its kernel stack.  The memory
 342  * management hardware is updated to the second process's state.
 343  * Finally, we can return to the second process, via ret_from_except.
 344  * On entry, r3 points to the THREAD for the current task, r4
 345  * points to the THREAD for the new task.
 346  *
 347  * Note: there are two ways to get to the "going out" portion
 348  * of this code; either by coming in via the entry (_switch)
 349  * or via "fork" which must set up an environment equivalent
 350  * to the "_switch" path.  If you change this you'll have to change
 351  * the fork code also.
 352  *
 353  * The code which creates the new task context is in 'copy_thread'
 354  * in arch/ppc64/kernel/process.c
 355  */
 356         .align  7
 357 _GLOBAL(_switch)
 358         mflr    r0
 359         std     r0,16(r1)
 360         stdu    r1,-SWITCH_FRAME_SIZE(r1)
 361         /* r3-r13 are caller saved -- Cort */
 362         SAVE_8GPRS(14, r1)
 363         SAVE_10GPRS(22, r1)
 364         mflr    r20             /* Return to switch caller */
 365         mfmsr   r22
 366         li      r0, MSR_FP
 367 #ifdef CONFIG_ALTIVEC
 368 BEGIN_FTR_SECTION
 369         oris    r0,r0,MSR_VEC@h /* Disable altivec */
 370         mfspr   r24,SPRN_VRSAVE /* save vrsave register value */
 371         std     r24,THREAD_VRSAVE(r3)
 372 END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
 373 #endif /* CONFIG_ALTIVEC */
 374         and.    r0,r0,r22
 375         beq+    1f
 376         andc    r22,r22,r0
 377         mtmsrd  r22
 378         isync
 379 1:      std     r20,_NIP(r1)
 380         mfcr    r23
 381         std     r23,_CCR(r1)
 382         std     r1,KSP(r3)      /* Set old stack pointer */
 383
 384 #ifdef CONFIG_SMP
 385         /* We need a sync somewhere here to make sure that if the
 386          * previous task gets rescheduled on another CPU, it sees all
 387          * stores it has performed on this one.
 388          */
 389         sync
 390 #endif /* CONFIG_SMP */
 391
 392         addi    r6,r4,-THREAD   /* Convert THREAD to 'current' */
 393         std     r6,PACACURRENT(r13)     /* Set new 'current' */
 394
 395         ld      r8,KSP(r4)      /* new stack pointer */
 396 BEGIN_FTR_SECTION
 397         clrrdi  r6,r8,28        /* get its ESID */
 398         clrrdi  r9,r1,28        /* get current sp ESID */
 399         clrldi. r0,r6,2         /* is new ESID c00000000? */
 400         cmpd    cr1,r6,r9       /* or is new ESID the same as current ESID? */
 401         cror    eq,4*cr1+eq,eq
 402         beq     2f              /* if yes, don't slbie it */
 403         oris    r0,r6,0x0800    /* set C (class) bit */
 404
 405         /* Bolt in the new stack SLB entry */
 406         ld      r7,KSP_VSID(r4) /* Get new stack's VSID */
 407         oris    r6,r6,(SLB_ESID_V)@h
 408         ori     r6,r6,(SLB_NUM_BOLTED-1)@l
 409         slbie   r0
 410         slbie   r0              /* Workaround POWER5 < DD2.1 issue */
 411         slbmte  r7,r6
 412         isync
 413
 414 2:
 415 END_FTR_SECTION_IFSET(CPU_FTR_SLB)
 416         clrrdi  r7,r8,THREAD_SHIFT      /* base of new stack */
 417         /* Note: this uses SWITCH_FRAME_SIZE rather than INT_FRAME_SIZE
 418            because we don't need to leave the 288-byte ABI gap at the
 419            top of the kernel stack. */
 420         addi    r7,r7,THREAD_SIZE-SWITCH_FRAME_SIZE
 421
 422         mr      r1,r8           /* start using new stack pointer */
 423         std     r7,PACAKSAVE(r13)
 424
 425         ld      r6,_CCR(r1)
 426         mtcrf   0xFF,r6
 427
 428 #ifdef CONFIG_ALTIVEC
 429 BEGIN_FTR_SECTION
 430         ld      r0,THREAD_VRSAVE(r4)
 431         mtspr   SPRN_VRSAVE,r0          /* if G4, restore VRSAVE reg */
 432 END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
 433 #endif /* CONFIG_ALTIVEC */
 434
 435         /* r3-r13 are destroyed -- Cort */
 436         REST_8GPRS(14, r1)
 437         REST_10GPRS(22, r1)
 438
 439 #ifdef CONFIG_PPC_ISERIES
 440         clrrdi  r7,r1,THREAD_SHIFT      /* get current_thread_info() */
 441         ld      r7,TI_FLAGS(r7)         /* Get run light flag */
 442         mfspr   r9,CTRLF
 443         srdi    r7,r7,TIF_RUN_LIGHT
 444         insrdi  r9,r7,1,63              /* Insert run light into CTRL */
 445         mtspr   CTRLT,r9
 446 #endif
 447
 448         /* convert old thread to its task_struct for return value */
 449         addi    r3,r3,-THREAD
 450         ld      r7,_NIP(r1)     /* Return to _switch caller in new task */
 451         mtlr    r7
 452         addi    r1,r1,SWITCH_FRAME_SIZE
 453         blr
 454
 455         .align  7
 456 _GLOBAL(ret_from_except)
 457         ld      r11,_TRAP(r1)
 458         andi.   r0,r11,1
 459         bne     .ret_from_except_lite
 460         REST_NVGPRS(r1)
 461
 462 _GLOBAL(ret_from_except_lite)
 463         /*
 464          * Disable interrupts so that current_thread_info()->flags
 465          * can't change between when we test it and when we return
 466          * from the interrupt.
 467          */
 468         mfmsr   r10             /* Get current interrupt state */
 469         rldicl  r9,r10,48,1     /* clear MSR_EE */
 470         rotldi  r9,r9,16
 471         mtmsrd  r9,1            /* Update machine state */
 472
 473 #ifdef CONFIG_PREEMPT
 474         clrrdi  r9,r1,THREAD_SHIFT      /* current_thread_info() */
 475         li      r0,_TIF_NEED_RESCHED    /* bits to check */
 476         ld      r3,_MSR(r1)
 477         ld      r4,TI_FLAGS(r9)
 478         /* Move MSR_PR bit in r3 to _TIF_SIGPENDING position in r0 */
 479         rlwimi  r0,r3,32+TIF_SIGPENDING-MSR_PR_LG,_TIF_SIGPENDING
 480         and.    r0,r4,r0        /* check NEED_RESCHED and maybe SIGPENDING */
 481         bne     do_work
 482
 483 #else /* !CONFIG_PREEMPT */
 484         ld      r3,_MSR(r1)     /* Returning to user mode? */
 485         andi.   r3,r3,MSR_PR
 486         beq     restore         /* if not, just restore regs and return */
 487
 488         /* Check current_thread_info()->flags */
 489         clrrdi  r9,r1,THREAD_SHIFT
 490         ld      r4,TI_FLAGS(r9)
 491         andi.   r0,r4,_TIF_USER_WORK_MASK
 492         bne     do_work
 493 #endif
 494
 495 restore:
 496 #ifdef CONFIG_PPC_ISERIES
 497         ld      r5,SOFTE(r1)
 498         cmpdi   0,r5,0
 499         beq     4f
 500         /* Check for pending interrupts (iSeries) */
 501         ld      r3,PACALPPACA+LPPACAANYINT(r13)
 502         cmpdi   r3,0
 503         beq+    4f                      /* skip do_IRQ if no interrupts */
 504
 505         li      r3,0
 506         stb     r3,PACAPROCENABLED(r13) /* ensure we are soft-disabled */
 507         ori     r10,r10,MSR_EE
 508         mtmsrd  r10                     /* hard-enable again */
 509         addi    r3,r1,STACK_FRAME_OVERHEAD
 510         bl      .do_IRQ
 511         b       .ret_from_except_lite           /* loop back and handle more */
 512
 513 4:      stb     r5,PACAPROCENABLED(r13)
 514 #endif
 515
 516         ld      r3,_MSR(r1)
 517         andi.   r0,r3,MSR_RI
 518         beq-    unrecov_restore
 519
 520         andi.   r0,r3,MSR_PR
 521
 522         /*
 523          * r13 is our per cpu area, only restore it if we are returning to
 524          * userspace
 525          */
 526         beq     1f
 527         REST_GPR(13, r1)
 528 1:
 529         ld      r3,_CTR(r1)
 530         ld      r0,_LINK(r1)
 531         mtctr   r3
 532         mtlr    r0
 533         ld      r3,_XER(r1)
 534         mtspr   XER,r3
 535
 536         REST_8GPRS(5, r1)
 537
 538         stdcx.  r0,0,r1         /* to clear the reservation */
 539
 540         mfmsr   r0
 541         li      r2, MSR_RI
 542         andc    r0,r0,r2
 543         mtmsrd  r0,1
 544
 545         ld      r0,_MSR(r1)
 546         mtspr   SRR1,r0
 547
 548         ld      r2,_CCR(r1)
 549         mtcrf   0xFF,r2
 550         ld      r2,_NIP(r1)
 551         mtspr   SRR0,r2
 552
 553         ld      r0,GPR0(r1)
 554         ld      r2,GPR2(r1)
 555         ld      r3,GPR3(r1)
 556         ld      r4,GPR4(r1)
 557         ld      r1,GPR1(r1)
 558
 559         rfid
 560         b       .       /* prevent speculative execution */
 561
 562 /* Note: this must change if we start using the TIF_NOTIFY_RESUME bit */
 563 do_work:
 564 #ifdef CONFIG_PREEMPT
 565         andi.   r0,r3,MSR_PR    /* Returning to user mode? */
 566         bne     user_work
 567         /* Check that preempt_count() == 0 and interrupts are enabled */
 568         lwz     r8,TI_PREEMPT(r9)
 569         cmpwi   cr1,r8,0
 570 #ifdef CONFIG_PPC_ISERIES
 571         ld      r0,SOFTE(r1)
 572         cmpdi   r0,0
 573 #else
 574         andi.   r0,r3,MSR_EE
 575 #endif
 576         crandc  eq,cr1*4+eq,eq
 577         bne     restore
 578         /* here we are preempting the current task */
 579 1:
 580 #ifdef CONFIG_PPC_ISERIES
 581         li      r0,1
 582         stb     r0,PACAPROCENABLED(r13)
 583 #endif
 584         ori     r10,r10,MSR_EE
 585         mtmsrd  r10,1           /* reenable interrupts */
 586         bl      .preempt_schedule
 587         mfmsr   r10
 588         clrrdi  r9,r1,THREAD_SHIFT
 589         rldicl  r10,r10,48,1    /* disable interrupts again */
 590         rotldi  r10,r10,16
 591         mtmsrd  r10,1
 592         ld      r4,TI_FLAGS(r9)
 593         andi.   r0,r4,_TIF_NEED_RESCHED
 594         bne     1b
 595         b       restore
 596
 597 user_work:
 598 #endif
 599         /* Enable interrupts */
 600         ori     r10,r10,MSR_EE
 601         mtmsrd  r10,1
 602
 603         andi.   r0,r4,_TIF_NEED_RESCHED
 604         beq     1f
 605         bl      .schedule
 606         b       .ret_from_except_lite
 607
 608 1:      bl      .save_nvgprs
 609         li      r3,0
 610         addi    r4,r1,STACK_FRAME_OVERHEAD
 611         bl      .do_signal
 612         b       .ret_from_except
 613
 614 unrecov_restore:
 615         addi    r3,r1,STACK_FRAME_OVERHEAD
 616         bl      .unrecoverable_exception
 617         b       unrecov_restore
 618
 619 #ifdef CONFIG_PPC_RTAS
 620 /*
 621  * On CHRP, the Run-Time Abstraction Services (RTAS) have to be
 622  * called with the MMU off.
 623  *
 624  * In addition, we need to be in 32b mode, at least for now.
 625  *
 626  * Note: r3 is an input parameter to rtas, so don't trash it...
 627  */
 628 _GLOBAL(enter_rtas)
 629         mflr    r0
 630         std     r0,16(r1)
 631         stdu    r1,-RTAS_FRAME_SIZE(r1) /* Save SP and create stack space. */
 632
 633         /* Because RTAS is running in 32b mode, it clobbers the high order half
 634          * of all registers that it saves.  We therefore save those registers
 635          * RTAS might touch to the stack.  (r0, r3-r13 are caller saved)
 636          */
 637         SAVE_GPR(2, r1)                 /* Save the TOC */
 638         SAVE_GPR(13, r1)                /* Save paca */
 639         SAVE_8GPRS(14, r1)              /* Save the non-volatiles */
 640         SAVE_10GPRS(22, r1)             /* ditto */
 641
 642         mfcr    r4
 643         std     r4,_CCR(r1)
 644         mfctr   r5
 645         std     r5,_CTR(r1)
 646         mfspr   r6,XER
 647         std     r6,_XER(r1)
 648         mfdar   r7
 649         std     r7,_DAR(r1)
 650         mfdsisr r8
 651         std     r8,_DSISR(r1)
 652         mfsrr0  r9
 653         std     r9,_SRR0(r1)
 654         mfsrr1  r10
 655         std     r10,_SRR1(r1)
 656
 657         /* There is no way it is acceptable to get here with interrupts enabled,
 658          * check it with the asm equivalent of WARN_ON
 659          */
 660         mfmsr   r6
 661         andi.   r0,r6,MSR_EE
 662 1:      tdnei   r0,0
 663 .section __bug_table,"a"
 664         .llong  1b,__LINE__ + 0x1000000, 1f, 2f
 665 .previous
 666 .section .rodata,"a"
 667 1:      .asciz  __FILE__
 668 2:      .asciz "enter_rtas"
 669 .previous
 670
 671         /* Unfortunately, the stack pointer and the MSR are also clobbered,
 672          * so they are saved in the PACA which allows us to restore
 673          * our original state after RTAS returns.
 674          */
 675         std     r1,PACAR1(r13)
 676         std     r6,PACASAVEDMSR(r13)
 677
 678         /* Setup our real return addr */
 679         SET_REG_TO_LABEL(r4,.rtas_return_loc)
 680         SET_REG_TO_CONST(r9,KERNELBASE)
 681         sub     r4,r4,r9
 682         mtlr    r4
 683
 684         li      r0,0
 685         ori     r0,r0,MSR_EE|MSR_SE|MSR_BE|MSR_RI
 686         andc    r0,r6,r0
 687
 688         li      r9,1
 689         rldicr  r9,r9,MSR_SF_LG,(63-MSR_SF_LG)
 690         ori     r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP
 691         andc    r6,r0,r9
 692         ori     r6,r6,MSR_RI
 693         sync                            /* disable interrupts so SRR0/1 */
 694         mtmsrd  r0                      /* don't get trashed */
 695
 696         SET_REG_TO_LABEL(r4,rtas)
 697         ld      r5,RTASENTRY(r4)        /* get the rtas->entry value */
 698         ld      r4,RTASBASE(r4)         /* get the rtas->base value */
 699
 700         mtspr   SRR0,r5
 701         mtspr   SRR1,r6
 702         rfid
 703         b       .       /* prevent speculative execution */
 704
 705 _STATIC(rtas_return_loc)
 706         /* relocation is off at this point */
 707         mfspr   r4,SPRG3                /* Get PACA */
 708         SET_REG_TO_CONST(r5, KERNELBASE)
 709         sub     r4,r4,r5                /* RELOC the PACA base pointer */
 710
 711         mfmsr   r6
 712         li      r0,MSR_RI
 713         andc    r6,r6,r0
 714         sync
 715         mtmsrd  r6
 716
 717         ld      r1,PACAR1(r4)           /* Restore our SP */
 718         LOADADDR(r3,.rtas_restore_regs)
 719         ld      r4,PACASAVEDMSR(r4)     /* Restore our MSR */
 720
 721         mtspr   SRR0,r3
 722         mtspr   SRR1,r4
 723         rfid
 724         b       .       /* prevent speculative execution */
 725
 726 _STATIC(rtas_restore_regs)
 727         /* relocation is on at this point */
 728         REST_GPR(2, r1)                 /* Restore the TOC */
 729         REST_GPR(13, r1)                /* Restore paca */
 730         REST_8GPRS(14, r1)              /* Restore the non-volatiles */
 731         REST_10GPRS(22, r1)             /* ditto */
 732
 733         mfspr   r13,SPRG3
 734
 735         ld      r4,_CCR(r1)
 736         mtcr    r4
 737         ld      r5,_CTR(r1)
 738         mtctr   r5
 739         ld      r6,_XER(r1)
 740         mtspr   XER,r6
 741         ld      r7,_DAR(r1)
 742         mtdar   r7
 743         ld      r8,_DSISR(r1)
 744         mtdsisr r8
 745         ld      r9,_SRR0(r1)
 746         mtsrr0  r9
 747         ld      r10,_SRR1(r1)
 748         mtsrr1  r10
 749
 750         addi    r1,r1,RTAS_FRAME_SIZE   /* Unstack our frame */
 751         ld      r0,16(r1)               /* get return address */
 752
 753         mtlr    r0
 754         blr                             /* return to caller */
 755
 756 #endif /* CONFIG_PPC_RTAS */
 757
 758 #ifdef CONFIG_PPC_MULTIPLATFORM
 759
 760 _GLOBAL(enter_prom)
 761         mflr    r0
 762         std     r0,16(r1)
 763         stdu    r1,-PROM_FRAME_SIZE(r1) /* Save SP and create stack space */
 764
 765         /* Because PROM is running in 32b mode, it clobbers the high order half
 766          * of all registers that it saves.  We therefore save those registers
 767          * PROM might touch to the stack.  (r0, r3-r13 are caller saved)
 768          */
 769         SAVE_8GPRS(2, r1)
 770         SAVE_GPR(13, r1)
 771         SAVE_8GPRS(14, r1)
 772         SAVE_10GPRS(22, r1)
 773         mfcr    r4
 774         std     r4,_CCR(r1)
 775         mfctr   r5
 776         std     r5,_CTR(r1)
 777         mfspr   r6,XER
 778         std     r6,_XER(r1)
 779         mfdar   r7
 780         std     r7,_DAR(r1)
 781         mfdsisr r8
 782         std     r8,_DSISR(r1)
 783         mfsrr0  r9
 784         std     r9,_SRR0(r1)
 785         mfsrr1  r10
 786         std     r10,_SRR1(r1)
 787         mfmsr   r11
 788         std     r11,_MSR(r1)
 789
 790         /* Get the PROM entrypoint */
 791         ld      r0,GPR4(r1)
 792         mtlr    r0
 793
 794         /* Switch MSR to 32 bits mode
 795          */
 796         mfmsr   r11
 797         li      r12,1
 798         rldicr  r12,r12,MSR_SF_LG,(63-MSR_SF_LG)
 799         andc    r11,r11,r12
 800         li      r12,1
 801         rldicr  r12,r12,MSR_ISF_LG,(63-MSR_ISF_LG)
 802         andc    r11,r11,r12
 803         mtmsrd  r11
 804         isync
 805
 806         /* Restore arguments & enter PROM here... */
 807         ld      r3,GPR3(r1)
 808         blrl
 809
 810         /* Just make sure that r1 top 32 bits didn't get
 811          * corrupt by OF
 812          */
 813         rldicl  r1,r1,0,32
 814
 815         /* Restore the MSR (back to 64 bits) */
 816         ld      r0,_MSR(r1)
 817         mtmsrd  r0
 818         isync
 819
 820         /* Restore other registers */
 821         REST_GPR(2, r1)
 822         REST_GPR(13, r1)
 823         REST_8GPRS(14, r1)
 824         REST_10GPRS(22, r1)
 825         ld      r4,_CCR(r1)
 826         mtcr    r4
 827         ld      r5,_CTR(r1)
 828         mtctr   r5
 829         ld      r6,_XER(r1)
 830         mtspr   XER,r6
 831         ld      r7,_DAR(r1)
 832         mtdar   r7
 833         ld      r8,_DSISR(r1)
 834         mtdsisr r8
 835         ld      r9,_SRR0(r1)
 836         mtsrr0  r9
 837         ld      r10,_SRR1(r1)
 838         mtsrr1  r10
 839
 840         addi    r1,r1,PROM_FRAME_SIZE
 841         ld      r0,16(r1)
 842         mtlr    r0
 843         blr
 844
 845 #endif  /* CONFIG_PPC_MULTIPLATFORM */