arch/openrisc/kernel/entry.S

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * OpenRISC entry.S
   4  *
   5  * Linux architectural port borrowing liberally from similar works of
   6  * others.  All original copyrights apply as per the original source
   7  * declaration.
   8  *
   9  * Modifications for the OpenRISC architecture:
  10  * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
  11  * Copyright (C) 2005 Gyorgy Jeney <nog@bsemi.com>
  12  * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  13  */
  14
  15 #include <linux/linkage.h>
  16 #include <linux/pgtable.h>
  17
  18 #include <asm/processor.h>
  19 #include <asm/unistd.h>
  20 #include <asm/thread_info.h>
  21 #include <asm/errno.h>
  22 #include <asm/spr_defs.h>
  23 #include <asm/page.h>
  24 #include <asm/mmu.h>
  25 #include <asm/asm-offsets.h>
  26
  27 #define DISABLE_INTERRUPTS(t1,t2)                       \
  28         l.mfspr t2,r0,SPR_SR                            ;\
  29         l.movhi t1,hi(~(SPR_SR_IEE|SPR_SR_TEE))         ;\
  30         l.ori   t1,t1,lo(~(SPR_SR_IEE|SPR_SR_TEE))      ;\
  31         l.and   t2,t2,t1                                ;\
  32         l.mtspr r0,t2,SPR_SR
  33
  34 #define ENABLE_INTERRUPTS(t1)                           \
  35         l.mfspr t1,r0,SPR_SR                            ;\
  36         l.ori   t1,t1,lo(SPR_SR_IEE|SPR_SR_TEE)         ;\
  37         l.mtspr r0,t1,SPR_SR
  38
  39 /* =========================================================[ macros ]=== */
  40
  41 #ifdef CONFIG_TRACE_IRQFLAGS
  42 /*
  43  * Trace irq on/off creating a stack frame.
  44  */
  45 #define TRACE_IRQS_OP(trace_op)                                 \
  46         l.sw    -8(r1),r2       /* store frame pointer */               ;\
  47         l.sw    -4(r1),r9       /* store return address */              ;\
  48         l.addi  r2,r1,0         /* move sp to fp */                     ;\
  49         l.jal   trace_op                                                ;\
  50          l.addi r1,r1,-8                                                ;\
  51         l.ori   r1,r2,0         /* restore sp */                        ;\
  52         l.lwz   r9,-4(r1)       /* restore return address */            ;\
  53         l.lwz   r2,-8(r1)       /* restore fp */                        ;\
  54 /*
  55  * Trace irq on/off and save registers we need that would otherwise be
  56  * clobbered.
  57  */
  58 #define TRACE_IRQS_SAVE(t1,trace_op)                                    \
  59         l.sw    -12(r1),t1      /* save extra reg */                    ;\
  60         l.sw    -8(r1),r2       /* store frame pointer */               ;\
  61         l.sw    -4(r1),r9       /* store return address */              ;\
  62         l.addi  r2,r1,0         /* move sp to fp */                     ;\
  63         l.jal   trace_op                                                ;\
  64          l.addi r1,r1,-12                                               ;\
  65         l.ori   r1,r2,0         /* restore sp */                        ;\
  66         l.lwz   r9,-4(r1)       /* restore return address */            ;\
  67         l.lwz   r2,-8(r1)       /* restore fp */                        ;\
  68         l.lwz   t1,-12(r1)      /* restore extra reg */
  69
  70 #define TRACE_IRQS_OFF  TRACE_IRQS_OP(trace_hardirqs_off)
  71 #define TRACE_IRQS_ON   TRACE_IRQS_OP(trace_hardirqs_on)
  72 #define TRACE_IRQS_ON_SYSCALL                                           \
  73         TRACE_IRQS_SAVE(r10,trace_hardirqs_on)                          ;\
  74         l.lwz   r3,PT_GPR3(r1)                                          ;\
  75         l.lwz   r4,PT_GPR4(r1)                                          ;\
  76         l.lwz   r5,PT_GPR5(r1)                                          ;\
  77         l.lwz   r6,PT_GPR6(r1)                                          ;\
  78         l.lwz   r7,PT_GPR7(r1)                                          ;\
  79         l.lwz   r8,PT_GPR8(r1)                                          ;\
  80         l.lwz   r11,PT_GPR11(r1)
  81 #define TRACE_IRQS_OFF_ENTRY                                            \
  82         l.lwz   r5,PT_SR(r1)                                            ;\
  83         l.andi  r3,r5,(SPR_SR_IEE|SPR_SR_TEE)                           ;\
  84         l.sfeq  r5,r0           /* skip trace if irqs were already off */;\
  85         l.bf    1f                                                      ;\
  86          l.nop                                                          ;\
  87         TRACE_IRQS_SAVE(r4,trace_hardirqs_off)                          ;\
  88 1:
  89 #else
  90 #define TRACE_IRQS_OFF
  91 #define TRACE_IRQS_ON
  92 #define TRACE_IRQS_OFF_ENTRY
  93 #define TRACE_IRQS_ON_SYSCALL
  94 #endif
  95
  96 /*
  97  * We need to disable interrupts at beginning of RESTORE_ALL
  98  * since interrupt might come in after we've loaded EPC return address
  99  * and overwrite EPC with address somewhere in RESTORE_ALL
 100  * which is of course wrong!
 101  */
 102
 103 #define RESTORE_ALL                                             \
 104         DISABLE_INTERRUPTS(r3,r4)                               ;\
 105         l.lwz   r3,PT_PC(r1)                                    ;\
 106         l.mtspr r0,r3,SPR_EPCR_BASE                             ;\
 107         l.lwz   r3,PT_SR(r1)                                    ;\
 108         l.mtspr r0,r3,SPR_ESR_BASE                              ;\
 109         l.lwz   r2,PT_GPR2(r1)                                  ;\
 110         l.lwz   r3,PT_GPR3(r1)                                  ;\
 111         l.lwz   r4,PT_GPR4(r1)                                  ;\
 112         l.lwz   r5,PT_GPR5(r1)                                  ;\
 113         l.lwz   r6,PT_GPR6(r1)                                  ;\
 114         l.lwz   r7,PT_GPR7(r1)                                  ;\
 115         l.lwz   r8,PT_GPR8(r1)                                  ;\
 116         l.lwz   r9,PT_GPR9(r1)                                  ;\
 117         l.lwz   r10,PT_GPR10(r1)                                        ;\
 118         l.lwz   r11,PT_GPR11(r1)                                        ;\
 119         l.lwz   r12,PT_GPR12(r1)                                        ;\
 120         l.lwz   r13,PT_GPR13(r1)                                        ;\
 121         l.lwz   r14,PT_GPR14(r1)                                        ;\
 122         l.lwz   r15,PT_GPR15(r1)                                        ;\
 123         l.lwz   r16,PT_GPR16(r1)                                        ;\
 124         l.lwz   r17,PT_GPR17(r1)                                        ;\
 125         l.lwz   r18,PT_GPR18(r1)                                        ;\
 126         l.lwz   r19,PT_GPR19(r1)                                        ;\
 127         l.lwz   r20,PT_GPR20(r1)                                        ;\
 128         l.lwz   r21,PT_GPR21(r1)                                        ;\
 129         l.lwz   r22,PT_GPR22(r1)                                        ;\
 130         l.lwz   r23,PT_GPR23(r1)                                        ;\
 131         l.lwz   r24,PT_GPR24(r1)                                        ;\
 132         l.lwz   r25,PT_GPR25(r1)                                        ;\
 133         l.lwz   r26,PT_GPR26(r1)                                        ;\
 134         l.lwz   r27,PT_GPR27(r1)                                        ;\
 135         l.lwz   r28,PT_GPR28(r1)                                        ;\
 136         l.lwz   r29,PT_GPR29(r1)                                        ;\
 137         l.lwz   r30,PT_GPR30(r1)                                        ;\
 138         l.lwz   r31,PT_GPR31(r1)                                        ;\
 139         l.lwz   r1,PT_SP(r1)                                    ;\
 140         l.rfe
 141
 142
 143 #define EXCEPTION_ENTRY(handler)                                \
 144         .global handler                                         ;\
 145 handler:                                                        ;\
 146         /* r1, EPCR, ESR a already saved */                     ;\
 147         l.sw    PT_GPR2(r1),r2                                  ;\
 148         l.sw    PT_GPR3(r1),r3                                  ;\
 149         /* r4 already save */                                   ;\
 150         l.sw    PT_GPR5(r1),r5                                  ;\
 151         l.sw    PT_GPR6(r1),r6                                  ;\
 152         l.sw    PT_GPR7(r1),r7                                  ;\
 153         l.sw    PT_GPR8(r1),r8                                  ;\
 154         l.sw    PT_GPR9(r1),r9                                  ;\
 155         /* r10 already saved */                                 ;\
 156         l.sw    PT_GPR11(r1),r11                                        ;\
 157         /* r12 already saved */                                 ;\
 158         l.sw    PT_GPR13(r1),r13                                        ;\
 159         l.sw    PT_GPR14(r1),r14                                        ;\
 160         l.sw    PT_GPR15(r1),r15                                        ;\
 161         l.sw    PT_GPR16(r1),r16                                        ;\
 162         l.sw    PT_GPR17(r1),r17                                        ;\
 163         l.sw    PT_GPR18(r1),r18                                        ;\
 164         l.sw    PT_GPR19(r1),r19                                        ;\
 165         l.sw    PT_GPR20(r1),r20                                        ;\
 166         l.sw    PT_GPR21(r1),r21                                        ;\
 167         l.sw    PT_GPR22(r1),r22                                        ;\
 168         l.sw    PT_GPR23(r1),r23                                        ;\
 169         l.sw    PT_GPR24(r1),r24                                        ;\
 170         l.sw    PT_GPR25(r1),r25                                        ;\
 171         l.sw    PT_GPR26(r1),r26                                        ;\
 172         l.sw    PT_GPR27(r1),r27                                        ;\
 173         l.sw    PT_GPR28(r1),r28                                        ;\
 174         l.sw    PT_GPR29(r1),r29                                        ;\
 175         /* r30 already save */                                  ;\
 176 /*        l.sw    PT_GPR30(r1),r30*/                                    ;\
 177         l.sw    PT_GPR31(r1),r31                                        ;\
 178         TRACE_IRQS_OFF_ENTRY                                            ;\
 179         /* Store -1 in orig_gpr11 for non-syscall exceptions */ ;\
 180         l.addi  r30,r0,-1                                       ;\
 181         l.sw    PT_ORIG_GPR11(r1),r30
 182
 183 #define UNHANDLED_EXCEPTION(handler,vector)                     \
 184         .global handler                                         ;\
 185 handler:                                                        ;\
 186         /* r1, EPCR, ESR already saved */                       ;\
 187         l.sw    PT_GPR2(r1),r2                                  ;\
 188         l.sw    PT_GPR3(r1),r3                                  ;\
 189         l.sw    PT_GPR5(r1),r5                                  ;\
 190         l.sw    PT_GPR6(r1),r6                                  ;\
 191         l.sw    PT_GPR7(r1),r7                                  ;\
 192         l.sw    PT_GPR8(r1),r8                                  ;\
 193         l.sw    PT_GPR9(r1),r9                                  ;\
 194         /* r10 already saved */                                 ;\
 195         l.sw    PT_GPR11(r1),r11                                        ;\
 196         /* r12 already saved */                                 ;\
 197         l.sw    PT_GPR13(r1),r13                                        ;\
 198         l.sw    PT_GPR14(r1),r14                                        ;\
 199         l.sw    PT_GPR15(r1),r15                                        ;\
 200         l.sw    PT_GPR16(r1),r16                                        ;\
 201         l.sw    PT_GPR17(r1),r17                                        ;\
 202         l.sw    PT_GPR18(r1),r18                                        ;\
 203         l.sw    PT_GPR19(r1),r19                                        ;\
 204         l.sw    PT_GPR20(r1),r20                                        ;\
 205         l.sw    PT_GPR21(r1),r21                                        ;\
 206         l.sw    PT_GPR22(r1),r22                                        ;\
 207         l.sw    PT_GPR23(r1),r23                                        ;\
 208         l.sw    PT_GPR24(r1),r24                                        ;\
 209         l.sw    PT_GPR25(r1),r25                                        ;\
 210         l.sw    PT_GPR26(r1),r26                                        ;\
 211         l.sw    PT_GPR27(r1),r27                                        ;\
 212         l.sw    PT_GPR28(r1),r28                                        ;\
 213         l.sw    PT_GPR29(r1),r29                                        ;\
 214         /* r31 already saved */                                 ;\
 215         l.sw    PT_GPR30(r1),r30                                        ;\
 216 /*        l.sw    PT_GPR31(r1),r31      */                              ;\
 217         /* Store -1 in orig_gpr11 for non-syscall exceptions */ ;\
 218         l.addi  r30,r0,-1                                       ;\
 219         l.sw    PT_ORIG_GPR11(r1),r30                           ;\
 220         l.addi  r3,r1,0                                         ;\
 221         /* r4 is exception EA */                                ;\
 222         l.addi  r5,r0,vector                                    ;\
 223         l.jal   unhandled_exception                             ;\
 224          l.nop                                                  ;\
 225         l.j     _ret_from_exception                             ;\
 226          l.nop
 227
 228 /* clobbers 'reg' */
 229 #define CLEAR_LWA_FLAG(reg)             \
 230         l.movhi reg,hi(lwa_flag)        ;\
 231         l.ori   reg,reg,lo(lwa_flag)    ;\
 232         l.sw    0(reg),r0
 233 /*
 234  * NOTE: one should never assume that SPR_EPC, SPR_ESR, SPR_EEAR
 235  *       contain the same values as when exception we're handling
 236  *       occured. in fact they never do. if you need them use
 237  *       values saved on stack (for SPR_EPC, SPR_ESR) or content
 238  *       of r4 (for SPR_EEAR). for details look at EXCEPTION_HANDLE()
 239  *       in 'arch/openrisc/kernel/head.S'
 240  */
 241
 242 /* =====================================================[ exceptions] === */
 243
 244 /* ---[ 0x100: RESET exception ]----------------------------------------- */
 245
 246 EXCEPTION_ENTRY(_tng_kernel_start)
 247         l.jal   _start
 248          l.andi r0,r0,0
 249
 250 /* ---[ 0x200: BUS exception ]------------------------------------------- */
 251
 252 EXCEPTION_ENTRY(_bus_fault_handler)
 253         CLEAR_LWA_FLAG(r3)
 254         /* r4: EA of fault (set by EXCEPTION_HANDLE) */
 255         l.jal   do_bus_fault
 256          l.addi  r3,r1,0 /* pt_regs */
 257
 258         l.j     _ret_from_exception
 259          l.nop
 260
 261 /* ---[ 0x300: Data Page Fault exception ]------------------------------- */
 262 EXCEPTION_ENTRY(_dtlb_miss_page_fault_handler)
 263         CLEAR_LWA_FLAG(r3)
 264         l.and   r5,r5,r0
 265         l.j     1f
 266          l.nop
 267
 268 EXCEPTION_ENTRY(_data_page_fault_handler)
 269         CLEAR_LWA_FLAG(r3)
 270         /* set up parameters for do_page_fault */
 271         l.ori   r5,r0,0x300                // exception vector
 272 1:
 273         l.addi  r3,r1,0                    // pt_regs
 274         /* r4 set be EXCEPTION_HANDLE */   // effective address of fault
 275
 276 #ifdef CONFIG_OPENRISC_NO_SPR_SR_DSX
 277         l.lwz   r6,PT_PC(r3)               // address of an offending insn
 278         l.lwz   r6,0(r6)                   // instruction that caused pf
 279
 280         l.srli  r6,r6,26                   // check opcode for jump insn
 281         l.sfeqi r6,0                       // l.j
 282         l.bf    8f
 283         l.sfeqi r6,1                       // l.jal
 284         l.bf    8f
 285         l.sfeqi r6,3                       // l.bnf
 286         l.bf    8f
 287         l.sfeqi r6,4                       // l.bf
 288         l.bf    8f
 289         l.sfeqi r6,0x11                    // l.jr
 290         l.bf    8f
 291         l.sfeqi r6,0x12                    // l.jalr
 292         l.bf    8f
 293          l.nop
 294
 295         l.j     9f
 296          l.nop
 297
 298 8: // offending insn is in delay slot
 299         l.lwz   r6,PT_PC(r3)               // address of an offending insn
 300         l.addi  r6,r6,4
 301         l.lwz   r6,0(r6)                   // instruction that caused pf
 302         l.srli  r6,r6,26                   // get opcode
 303 9: // offending instruction opcode loaded in r6
 304
 305 #else
 306
 307         l.mfspr r6,r0,SPR_SR               // SR
 308         l.andi  r6,r6,SPR_SR_DSX           // check for delay slot exception
 309         l.sfne  r6,r0                      // exception happened in delay slot
 310         l.bnf   7f
 311          l.lwz  r6,PT_PC(r3)               // address of an offending insn
 312
 313         l.addi  r6,r6,4                    // offending insn is in delay slot
 314 7:
 315         l.lwz   r6,0(r6)                   // instruction that caused pf
 316         l.srli  r6,r6,26                   // check opcode for write access
 317 #endif
 318
 319         l.sfgeui r6,0x33                   // check opcode for write access
 320         l.bnf   1f
 321         l.sfleui r6,0x37
 322         l.bnf   1f
 323         l.ori   r6,r0,0x1                  // write access
 324         l.j     2f
 325          l.nop
 326 1:      l.ori   r6,r0,0x0                  // !write access
 327 2:
 328
 329         /* call fault.c handler in or32/mm/fault.c */
 330         l.jal   do_page_fault
 331          l.nop
 332         l.j     _ret_from_exception
 333          l.nop
 334
 335 /* ---[ 0x400: Insn Page Fault exception ]------------------------------- */
 336 EXCEPTION_ENTRY(_itlb_miss_page_fault_handler)
 337         CLEAR_LWA_FLAG(r3)
 338         l.and   r5,r5,r0
 339         l.j     1f
 340          l.nop
 341
 342 EXCEPTION_ENTRY(_insn_page_fault_handler)
 343         CLEAR_LWA_FLAG(r3)
 344         /* set up parameters for do_page_fault */
 345         l.ori   r5,r0,0x400                // exception vector
 346 1:
 347         l.addi  r3,r1,0                    // pt_regs
 348         /* r4 set be EXCEPTION_HANDLE */   // effective address of fault
 349         l.ori   r6,r0,0x0                  // !write access
 350
 351         /* call fault.c handler in or32/mm/fault.c */
 352         l.jal   do_page_fault
 353          l.nop
 354         l.j     _ret_from_exception
 355          l.nop
 356
 357
 358 /* ---[ 0x500: Timer exception ]----------------------------------------- */
 359
 360 EXCEPTION_ENTRY(_timer_handler)
 361         CLEAR_LWA_FLAG(r3)
 362         l.jal   timer_interrupt
 363          l.addi r3,r1,0 /* pt_regs */
 364
 365         l.j    _ret_from_intr
 366          l.nop
 367
 368 /* ---[ 0x600: Alignment exception ]-------------------------------------- */
 369
 370 EXCEPTION_ENTRY(_alignment_handler)
 371         CLEAR_LWA_FLAG(r3)
 372         /* r4: EA of fault (set by EXCEPTION_HANDLE) */
 373         l.jal   do_unaligned_access
 374          l.addi  r3,r1,0 /* pt_regs */
 375
 376         l.j     _ret_from_exception
 377          l.nop
 378
 379 #if 0
 380 EXCEPTION_ENTRY(_alignment_handler)
 381 //        l.mfspr r2,r0,SPR_EEAR_BASE     /* Load the effective address */
 382         l.addi  r2,r4,0
 383 //        l.mfspr r5,r0,SPR_EPCR_BASE     /* Load the insn address */
 384         l.lwz   r5,PT_PC(r1)
 385
 386         l.lwz   r3,0(r5)                /* Load insn */
 387         l.srli  r4,r3,26                /* Shift left to get the insn opcode */
 388
 389         l.sfeqi r4,0x00                 /* Check if the load/store insn is in delay slot */
 390         l.bf    jmp
 391         l.sfeqi r4,0x01
 392         l.bf    jmp
 393         l.sfeqi r4,0x03
 394         l.bf    jmp
 395         l.sfeqi r4,0x04
 396         l.bf    jmp
 397         l.sfeqi r4,0x11
 398         l.bf    jr
 399         l.sfeqi r4,0x12
 400         l.bf    jr
 401         l.nop
 402         l.j     1f
 403         l.addi  r5,r5,4                 /* Increment PC to get return insn address */
 404
 405 jmp:
 406         l.slli  r4,r3,6                 /* Get the signed extended jump length */
 407         l.srai  r4,r4,4
 408
 409         l.lwz   r3,4(r5)                /* Load the real load/store insn */
 410
 411         l.add   r5,r5,r4                /* Calculate jump target address */
 412
 413         l.j     1f
 414         l.srli  r4,r3,26                /* Shift left to get the insn opcode */
 415
 416 jr:
 417         l.slli  r4,r3,9                 /* Shift to get the reg nb */
 418         l.andi  r4,r4,0x7c
 419
 420         l.lwz   r3,4(r5)                /* Load the real load/store insn */
 421
 422         l.add   r4,r4,r1                /* Load the jump register value from the stack */
 423         l.lwz   r5,0(r4)
 424
 425         l.srli  r4,r3,26                /* Shift left to get the insn opcode */
 426
 427
 428 1:
 429 //        l.mtspr r0,r5,SPR_EPCR_BASE
 430         l.sw    PT_PC(r1),r5
 431
 432         l.sfeqi r4,0x26
 433         l.bf    lhs
 434         l.sfeqi r4,0x25
 435         l.bf    lhz
 436         l.sfeqi r4,0x22
 437         l.bf    lws
 438         l.sfeqi r4,0x21
 439         l.bf    lwz
 440         l.sfeqi r4,0x37
 441         l.bf    sh
 442         l.sfeqi r4,0x35
 443         l.bf    sw
 444         l.nop
 445
 446 1:      l.j     1b                      /* I don't know what to do */
 447         l.nop
 448
 449 lhs:    l.lbs   r5,0(r2)
 450         l.slli  r5,r5,8
 451         l.lbz   r6,1(r2)
 452         l.or    r5,r5,r6
 453         l.srli  r4,r3,19
 454         l.andi  r4,r4,0x7c
 455         l.add   r4,r4,r1
 456         l.j     align_end
 457         l.sw    0(r4),r5
 458
 459 lhz:    l.lbz   r5,0(r2)
 460         l.slli  r5,r5,8
 461         l.lbz   r6,1(r2)
 462         l.or    r5,r5,r6
 463         l.srli  r4,r3,19
 464         l.andi  r4,r4,0x7c
 465         l.add   r4,r4,r1
 466         l.j     align_end
 467         l.sw    0(r4),r5
 468
 469 lws:    l.lbs   r5,0(r2)
 470         l.slli  r5,r5,24
 471         l.lbz   r6,1(r2)
 472         l.slli  r6,r6,16
 473         l.or    r5,r5,r6
 474         l.lbz   r6,2(r2)
 475         l.slli  r6,r6,8
 476         l.or    r5,r5,r6
 477         l.lbz   r6,3(r2)
 478         l.or    r5,r5,r6
 479         l.srli  r4,r3,19
 480         l.andi  r4,r4,0x7c
 481         l.add   r4,r4,r1
 482         l.j     align_end
 483         l.sw    0(r4),r5
 484
 485 lwz:    l.lbz   r5,0(r2)
 486         l.slli  r5,r5,24
 487         l.lbz   r6,1(r2)
 488         l.slli  r6,r6,16
 489         l.or    r5,r5,r6
 490         l.lbz   r6,2(r2)
 491         l.slli  r6,r6,8
 492         l.or    r5,r5,r6
 493         l.lbz   r6,3(r2)
 494         l.or    r5,r5,r6
 495         l.srli  r4,r3,19
 496         l.andi  r4,r4,0x7c
 497         l.add   r4,r4,r1
 498         l.j     align_end
 499         l.sw    0(r4),r5
 500
 501 sh:
 502         l.srli  r4,r3,9
 503         l.andi  r4,r4,0x7c
 504         l.add   r4,r4,r1
 505         l.lwz   r5,0(r4)
 506         l.sb    1(r2),r5
 507         l.srli  r5,r5,8
 508         l.j     align_end
 509         l.sb    0(r2),r5
 510
 511 sw:
 512         l.srli  r4,r3,9
 513         l.andi  r4,r4,0x7c
 514         l.add   r4,r4,r1
 515         l.lwz   r5,0(r4)
 516         l.sb    3(r2),r5
 517         l.srli  r5,r5,8
 518         l.sb    2(r2),r5
 519         l.srli  r5,r5,8
 520         l.sb    1(r2),r5
 521         l.srli  r5,r5,8
 522         l.j     align_end
 523         l.sb    0(r2),r5
 524
 525 align_end:
 526         l.j    _ret_from_intr
 527         l.nop
 528 #endif
 529
 530 /* ---[ 0x700: Illegal insn exception ]---------------------------------- */
 531
 532 EXCEPTION_ENTRY(_illegal_instruction_handler)
 533         /* r4: EA of fault (set by EXCEPTION_HANDLE) */
 534         l.jal   do_illegal_instruction
 535          l.addi  r3,r1,0 /* pt_regs */
 536
 537         l.j     _ret_from_exception
 538          l.nop
 539
 540 /* ---[ 0x800: External interrupt exception ]---------------------------- */
 541
 542 EXCEPTION_ENTRY(_external_irq_handler)
 543 #ifdef CONFIG_OPENRISC_ESR_EXCEPTION_BUG_CHECK
 544         l.lwz   r4,PT_SR(r1)            // were interrupts enabled ?
 545         l.andi  r4,r4,SPR_SR_IEE
 546         l.sfeqi r4,0
 547         l.bnf   1f                      // ext irq enabled, all ok.
 548         l.nop
 549
 550         l.addi  r1,r1,-0x8
 551         l.movhi r3,hi(42f)
 552         l.ori   r3,r3,lo(42f)
 553         l.sw    0x0(r1),r3
 554         l.jal   _printk
 555         l.sw    0x4(r1),r4
 556         l.addi  r1,r1,0x8
 557
 558         .section .rodata, "a"
 559 42:
 560                 .string "\n\rESR interrupt bug: in _external_irq_handler (ESR %x)\n\r"
 561                 .align 4
 562         .previous
 563
 564         l.ori   r4,r4,SPR_SR_IEE        // fix the bug
 565 //      l.sw    PT_SR(r1),r4
 566 1:
 567 #endif
 568         CLEAR_LWA_FLAG(r3)
 569         l.addi  r3,r1,0
 570         l.movhi r8,hi(do_IRQ)
 571         l.ori   r8,r8,lo(do_IRQ)
 572         l.jalr r8
 573         l.nop
 574         l.j    _ret_from_intr
 575         l.nop
 576
 577 /* ---[ 0x900: DTLB miss exception ]------------------------------------- */
 578
 579
 580 /* ---[ 0xa00: ITLB miss exception ]------------------------------------- */
 581
 582
 583 /* ---[ 0xb00: Range exception ]----------------------------------------- */
 584
 585 UNHANDLED_EXCEPTION(_vector_0xb00,0xb00)
 586
 587 /* ---[ 0xc00: Syscall exception ]--------------------------------------- */
 588
 589 /*
 590  * Syscalls are a special type of exception in that they are
 591  * _explicitly_ invoked by userspace and can therefore be
 592  * held to conform to the same ABI as normal functions with
 593  * respect to whether registers are preserved across the call
 594  * or not.
 595  */
 596
 597 /* Upon syscall entry we just save the callee-saved registers
 598  * and not the call-clobbered ones.
 599  */
 600
 601 _string_syscall_return:
 602         .string "syscall return %ld \n\r\0"
 603         .align 4
 604
 605 ENTRY(_sys_call_handler)
 606         /* r1, EPCR, ESR a already saved */
 607         l.sw    PT_GPR2(r1),r2
 608         /* r3-r8 must be saved because syscall restart relies
 609          * on us being able to restart the syscall args... technically
 610          * they should be clobbered, otherwise
 611          */
 612         l.sw    PT_GPR3(r1),r3
 613         /*
 614          * r4 already saved
 615          * r4 holds the EEAR address of the fault, use it as screatch reg and
 616          * then load the original r4
 617          */
 618         CLEAR_LWA_FLAG(r4)
 619         l.lwz   r4,PT_GPR4(r1)
 620         l.sw    PT_GPR5(r1),r5
 621         l.sw    PT_GPR6(r1),r6
 622         l.sw    PT_GPR7(r1),r7
 623         l.sw    PT_GPR8(r1),r8
 624         l.sw    PT_GPR9(r1),r9
 625         /* r10 already saved */
 626         l.sw    PT_GPR11(r1),r11
 627         /* orig_gpr11 must be set for syscalls */
 628         l.sw    PT_ORIG_GPR11(r1),r11
 629         /* r12,r13 already saved */
 630
 631         /* r14-r28 (even) aren't touched by the syscall fast path below
 632          * so we don't need to save them.  However, the functions that return
 633          * to userspace via a call to switch() DO need to save these because
 634          * switch() effectively clobbers them... saving these registers for
 635          * such functions is handled in their syscall wrappers (see fork, vfork,
 636          * and clone, below).
 637
 638         /* r30 is the only register we clobber in the fast path */
 639         /* r30 already saved */
 640 /*      l.sw    PT_GPR30(r1),r30 */
 641
 642 _syscall_check_trace_enter:
 643         /* syscalls run with interrupts enabled */
 644         TRACE_IRQS_ON_SYSCALL
 645         ENABLE_INTERRUPTS(r29)          // enable interrupts, r29 is temp
 646
 647         /* If TIF_SYSCALL_TRACE is set, then we want to do syscall tracing */
 648         l.lwz   r30,TI_FLAGS(r10)
 649         l.andi  r30,r30,_TIF_SYSCALL_TRACE
 650         l.sfne  r30,r0
 651         l.bf    _syscall_trace_enter
 652          l.nop
 653
 654 _syscall_check:
 655         /* Ensure that the syscall number is reasonable */
 656         l.sfgeui r11,__NR_syscalls
 657         l.bf    _syscall_badsys
 658          l.nop
 659
 660 _syscall_call:
 661         l.movhi r29,hi(sys_call_table)
 662         l.ori   r29,r29,lo(sys_call_table)
 663         l.slli  r11,r11,2
 664         l.add   r29,r29,r11
 665         l.lwz   r29,0(r29)
 666
 667         l.jalr  r29
 668          l.nop
 669
 670 _syscall_return:
 671         /* All syscalls return here... just pay attention to ret_from_fork
 672          * which does it in a round-about way.
 673          */
 674         l.sw    PT_GPR11(r1),r11           // save return value
 675
 676 #if 0
 677 _syscall_debug:
 678         l.movhi r3,hi(_string_syscall_return)
 679         l.ori   r3,r3,lo(_string_syscall_return)
 680         l.ori   r27,r0,1
 681         l.sw    -4(r1),r27
 682         l.sw    -8(r1),r11
 683         l.addi  r1,r1,-8
 684         l.movhi r27,hi(_printk)
 685         l.ori   r27,r27,lo(_printk)
 686         l.jalr  r27
 687          l.nop
 688         l.addi  r1,r1,8
 689 #endif
 690
 691 _syscall_check_trace_leave:
 692         /* r30 is a callee-saved register so this should still hold the
 693          * _TIF_SYSCALL_TRACE flag from _syscall_check_trace_enter above...
 694          * _syscall_trace_leave expects syscall result to be in pt_regs->r11.
 695          */
 696         l.sfne  r30,r0
 697         l.bf    _syscall_trace_leave
 698          l.nop
 699
 700 /* This is where the exception-return code begins... interrupts need to be
 701  * disabled the rest of the way here because we can't afford to miss any
 702  * interrupts that set NEED_RESCHED or SIGNALPENDING... really true? */
 703
 704 _syscall_check_work:
 705         /* Here we need to disable interrupts */
 706         DISABLE_INTERRUPTS(r27,r29)
 707         TRACE_IRQS_OFF
 708         l.lwz   r30,TI_FLAGS(r10)
 709         l.andi  r30,r30,_TIF_WORK_MASK
 710         l.sfne  r30,r0
 711
 712         l.bnf   _syscall_resume_userspace
 713          l.nop
 714
 715         /* Work pending follows a different return path, so we need to
 716          * make sure that all the call-saved registers get into pt_regs
 717          * before branching...
 718          */
 719         l.sw    PT_GPR14(r1),r14
 720         l.sw    PT_GPR16(r1),r16
 721         l.sw    PT_GPR18(r1),r18
 722         l.sw    PT_GPR20(r1),r20
 723         l.sw    PT_GPR22(r1),r22
 724         l.sw    PT_GPR24(r1),r24
 725         l.sw    PT_GPR26(r1),r26
 726         l.sw    PT_GPR28(r1),r28
 727
 728         /* _work_pending needs to be called with interrupts disabled */
 729         l.j     _work_pending
 730          l.nop
 731
 732 _syscall_resume_userspace:
 733 //      ENABLE_INTERRUPTS(r29)
 734
 735
 736 /* This is the hot path for returning to userspace from a syscall.  If there's
 737  * work to be done and the branch to _work_pending was taken above, then the
 738  * return to userspace will be done via the normal exception return path...
 739  * that path restores _all_ registers and will overwrite the "clobbered"
 740  * registers with whatever garbage is in pt_regs -- that's OK because those
 741  * registers are clobbered anyway and because the extra work is insignificant
 742  * in the context of the extra work that _work_pending is doing.
 743
 744 /* Once again, syscalls are special and only guarantee to preserve the
 745  * same registers as a normal function call */
 746
 747 /* The assumption here is that the registers r14-r28 (even) are untouched and
 748  * don't need to be restored... be sure that that's really the case!
 749  */
 750
 751 /* This is still too much... we should only be restoring what we actually
 752  * clobbered... we should even be using 'scratch' (odd) regs above so that
 753  * we don't need to restore anything, hardly...
 754  */
 755
 756         l.lwz   r2,PT_GPR2(r1)
 757
 758         /* Restore args */
 759         /* r3-r8 are technically clobbered, but syscall restart needs these
 760          * to be restored...
 761          */
 762         l.lwz   r3,PT_GPR3(r1)
 763         l.lwz   r4,PT_GPR4(r1)
 764         l.lwz   r5,PT_GPR5(r1)
 765         l.lwz   r6,PT_GPR6(r1)
 766         l.lwz   r7,PT_GPR7(r1)
 767         l.lwz   r8,PT_GPR8(r1)
 768
 769         l.lwz   r9,PT_GPR9(r1)
 770         l.lwz   r10,PT_GPR10(r1)
 771         l.lwz   r11,PT_GPR11(r1)
 772
 773         /* r30 is the only register we clobber in the fast path */
 774         l.lwz   r30,PT_GPR30(r1)
 775
 776         /* Here we use r13-r19 (odd) as scratch regs */
 777         l.lwz   r13,PT_PC(r1)
 778         l.lwz   r15,PT_SR(r1)
 779         l.lwz   r1,PT_SP(r1)
 780         /* Interrupts need to be disabled for setting EPCR and ESR
 781          * so that another interrupt doesn't come in here and clobber
 782          * them before we can use them for our l.rfe */
 783         DISABLE_INTERRUPTS(r17,r19)
 784         l.mtspr r0,r13,SPR_EPCR_BASE
 785         l.mtspr r0,r15,SPR_ESR_BASE
 786         l.rfe
 787
 788 /* End of hot path!
 789  * Keep the below tracing and error handling out of the hot path...
 790 */
 791
 792 _syscall_trace_enter:
 793         /* Here we pass pt_regs to do_syscall_trace_enter.  Make sure
 794          * that function is really getting all the info it needs as
 795          * pt_regs isn't a complete set of userspace regs, just the
 796          * ones relevant to the syscall...
 797          *
 798          * Note use of delay slot for setting argument.
 799          */
 800         l.jal   do_syscall_trace_enter
 801          l.addi r3,r1,0
 802
 803         /* Restore arguments (not preserved across do_syscall_trace_enter)
 804          * so that we can do the syscall for real and return to the syscall
 805          * hot path.
 806          */
 807         l.lwz   r11,PT_GPR11(r1)
 808         l.lwz   r3,PT_GPR3(r1)
 809         l.lwz   r4,PT_GPR4(r1)
 810         l.lwz   r5,PT_GPR5(r1)
 811         l.lwz   r6,PT_GPR6(r1)
 812         l.lwz   r7,PT_GPR7(r1)
 813
 814         l.j     _syscall_check
 815          l.lwz  r8,PT_GPR8(r1)
 816
 817 _syscall_trace_leave:
 818         l.jal   do_syscall_trace_leave
 819          l.addi r3,r1,0
 820
 821         l.j     _syscall_check_work
 822          l.nop
 823
 824 _syscall_badsys:
 825         /* Here we effectively pretend to have executed an imaginary
 826          * syscall that returns -ENOSYS and then return to the regular
 827          * syscall hot path.
 828          * Note that "return value" is set in the delay slot...
 829          */
 830         l.j     _syscall_return
 831          l.addi r11,r0,-ENOSYS
 832
 833 /******* END SYSCALL HANDLING *******/
 834
 835 /* ---[ 0xd00: Trap exception ]------------------------------------------ */
 836
 837 UNHANDLED_EXCEPTION(_vector_0xd00,0xd00)
 838
 839 /* ---[ 0xe00: Trap exception ]------------------------------------------ */
 840
 841 EXCEPTION_ENTRY(_trap_handler)
 842         CLEAR_LWA_FLAG(r3)
 843         /* r4: EA of fault (set by EXCEPTION_HANDLE) */
 844         l.jal   do_trap
 845          l.addi  r3,r1,0 /* pt_regs */
 846
 847         l.j     _ret_from_exception
 848          l.nop
 849
 850 /* ---[ 0xf00: Reserved exception ]-------------------------------------- */
 851
 852 UNHANDLED_EXCEPTION(_vector_0xf00,0xf00)
 853
 854 /* ---[ 0x1000: Reserved exception ]------------------------------------- */
 855
 856 UNHANDLED_EXCEPTION(_vector_0x1000,0x1000)
 857
 858 /* ---[ 0x1100: Reserved exception ]------------------------------------- */
 859
 860 UNHANDLED_EXCEPTION(_vector_0x1100,0x1100)
 861
 862 /* ---[ 0x1200: Reserved exception ]------------------------------------- */
 863
 864 UNHANDLED_EXCEPTION(_vector_0x1200,0x1200)
 865
 866 /* ---[ 0x1300: Reserved exception ]------------------------------------- */
 867
 868 UNHANDLED_EXCEPTION(_vector_0x1300,0x1300)
 869
 870 /* ---[ 0x1400: Reserved exception ]------------------------------------- */
 871
 872 UNHANDLED_EXCEPTION(_vector_0x1400,0x1400)
 873
 874 /* ---[ 0x1500: Reserved exception ]------------------------------------- */
 875
 876 UNHANDLED_EXCEPTION(_vector_0x1500,0x1500)
 877
 878 /* ---[ 0x1600: Reserved exception ]------------------------------------- */
 879
 880 UNHANDLED_EXCEPTION(_vector_0x1600,0x1600)
 881
 882 /* ---[ 0x1700: Reserved exception ]------------------------------------- */
 883
 884 UNHANDLED_EXCEPTION(_vector_0x1700,0x1700)
 885
 886 /* ---[ 0x1800: Reserved exception ]------------------------------------- */
 887
 888 UNHANDLED_EXCEPTION(_vector_0x1800,0x1800)
 889
 890 /* ---[ 0x1900: Reserved exception ]------------------------------------- */
 891
 892 UNHANDLED_EXCEPTION(_vector_0x1900,0x1900)
 893
 894 /* ---[ 0x1a00: Reserved exception ]------------------------------------- */
 895
 896 UNHANDLED_EXCEPTION(_vector_0x1a00,0x1a00)
 897
 898 /* ---[ 0x1b00: Reserved exception ]------------------------------------- */
 899
 900 UNHANDLED_EXCEPTION(_vector_0x1b00,0x1b00)
 901
 902 /* ---[ 0x1c00: Reserved exception ]------------------------------------- */
 903
 904 UNHANDLED_EXCEPTION(_vector_0x1c00,0x1c00)
 905
 906 /* ---[ 0x1d00: Reserved exception ]------------------------------------- */
 907
 908 UNHANDLED_EXCEPTION(_vector_0x1d00,0x1d00)
 909
 910 /* ---[ 0x1e00: Reserved exception ]------------------------------------- */
 911
 912 UNHANDLED_EXCEPTION(_vector_0x1e00,0x1e00)
 913
 914 /* ---[ 0x1f00: Reserved exception ]------------------------------------- */
 915
 916 UNHANDLED_EXCEPTION(_vector_0x1f00,0x1f00)
 917
 918 /* ========================================================[ return ] === */
 919
 920 _resume_userspace:
 921         DISABLE_INTERRUPTS(r3,r4)
 922         TRACE_IRQS_OFF
 923         l.lwz   r4,TI_FLAGS(r10)
 924         l.andi  r13,r4,_TIF_WORK_MASK
 925         l.sfeqi r13,0
 926         l.bf    _restore_all
 927          l.nop
 928
 929 _work_pending:
 930         l.lwz   r5,PT_ORIG_GPR11(r1)
 931         l.sfltsi r5,0
 932         l.bnf   1f
 933          l.nop
 934         l.andi  r5,r5,0
 935 1:
 936         l.jal   do_work_pending
 937          l.ori  r3,r1,0                 /* pt_regs */
 938
 939         l.sfeqi r11,0
 940         l.bf    _restore_all
 941          l.nop
 942         l.sfltsi r11,0
 943         l.bnf   1f
 944          l.nop
 945         l.and   r11,r11,r0
 946         l.ori   r11,r11,__NR_restart_syscall
 947         l.j     _syscall_check_trace_enter
 948          l.nop
 949 1:
 950         l.lwz   r11,PT_ORIG_GPR11(r1)
 951         /* Restore arg registers */
 952         l.lwz   r3,PT_GPR3(r1)
 953         l.lwz   r4,PT_GPR4(r1)
 954         l.lwz   r5,PT_GPR5(r1)
 955         l.lwz   r6,PT_GPR6(r1)
 956         l.lwz   r7,PT_GPR7(r1)
 957         l.j     _syscall_check_trace_enter
 958          l.lwz  r8,PT_GPR8(r1)
 959
 960 _restore_all:
 961 #ifdef CONFIG_TRACE_IRQFLAGS
 962         l.lwz   r4,PT_SR(r1)
 963         l.andi  r3,r4,(SPR_SR_IEE|SPR_SR_TEE)
 964         l.sfeq  r3,r0           /* skip trace if irqs were off */
 965         l.bf    skip_hardirqs_on
 966          l.nop
 967         TRACE_IRQS_ON
 968 skip_hardirqs_on:
 969 #endif
 970         RESTORE_ALL
 971         /* This returns to userspace code */
 972
 973
 974 ENTRY(_ret_from_intr)
 975 ENTRY(_ret_from_exception)
 976         l.lwz   r4,PT_SR(r1)
 977         l.andi  r3,r4,SPR_SR_SM
 978         l.sfeqi r3,0
 979         l.bnf   _restore_all
 980          l.nop
 981         l.j     _resume_userspace
 982          l.nop
 983
 984 ENTRY(ret_from_fork)
 985         l.jal   schedule_tail
 986          l.nop
 987
 988         /* Check if we are a kernel thread */
 989         l.sfeqi r20,0
 990         l.bf    1f
 991          l.nop
 992
 993         /* ...we are a kernel thread so invoke the requested callback */
 994         l.jalr  r20
 995          l.or   r3,r22,r0
 996
 997 1:
 998         /* _syscall_returns expect r11 to contain return value */
 999         l.lwz   r11,PT_GPR11(r1)
1000
1001         /* The syscall fast path return expects call-saved registers
1002          * r12-r28 to be untouched, so we restore them here as they
1003          * will have been effectively clobbered when arriving here
1004          * via the call to switch()
1005          */
1006         l.lwz   r12,PT_GPR12(r1)
1007         l.lwz   r14,PT_GPR14(r1)
1008         l.lwz   r16,PT_GPR16(r1)
1009         l.lwz   r18,PT_GPR18(r1)
1010         l.lwz   r20,PT_GPR20(r1)
1011         l.lwz   r22,PT_GPR22(r1)
1012         l.lwz   r24,PT_GPR24(r1)
1013         l.lwz   r26,PT_GPR26(r1)
1014         l.lwz   r28,PT_GPR28(r1)
1015
1016         l.j     _syscall_return
1017          l.nop
1018
1019 /* ========================================================[ switch ] === */
1020
1021 /*
1022  * This routine switches between two different tasks.  The process
1023  * state of one is saved on its kernel stack.  Then the state
1024  * of the other is restored from its kernel stack.  The memory
1025  * management hardware is updated to the second process's state.
1026  * Finally, we can return to the second process, via the 'return'.
1027  *
1028  * Note: there are two ways to get to the "going out" portion
1029  * of this code; either by coming in via the entry (_switch)
1030  * or via "fork" which must set up an environment equivalent
1031  * to the "_switch" path.  If you change this (or in particular, the
1032  * SAVE_REGS macro), you'll have to change the fork code also.
1033  */
1034
1035
1036 /* _switch MUST never lay on page boundry, cause it runs from
1037  * effective addresses and beeing interrupted by iTLB miss would kill it.
1038  * dTLB miss seams to never accour in the bad place since data accesses
1039  * are from task structures which are always page aligned.
1040  *
1041  * The problem happens in RESTORE_ALL_NO_R11 where we first set the EPCR
1042  * register, then load the previous register values and only at the end call
1043  * the l.rfe instruction. If get TLB miss in beetwen the EPCR register gets
1044  * garbled and we end up calling l.rfe with the wrong EPCR. (same probably
1045  * holds for ESR)
1046  *
1047  * To avoid this problems it is sufficient to align _switch to
1048  * some nice round number smaller than it's size...
1049  */
1050
1051 /* ABI rules apply here... we either enter _switch via schedule() or via
1052  * an imaginary call to which we shall return at return_from_fork.  Either
1053  * way, we are a function call and only need to preserve the callee-saved
1054  * registers when we return.  As such, we don't need to save the registers
1055  * on the stack that we won't be returning as they were...
1056  */
1057
1058         .align 0x400
1059 ENTRY(_switch)
1060         /* We don't store SR as _switch only gets called in a context where
1061          * the SR will be the same going in and coming out... */
1062
1063         /* Set up new pt_regs struct for saving task state */
1064         l.addi  r1,r1,-(INT_FRAME_SIZE)
1065
1066         /* No need to store r1/PT_SP as it goes into KSP below */
1067         l.sw    PT_GPR2(r1),r2
1068         l.sw    PT_GPR9(r1),r9
1069         /* This is wrong, r12 shouldn't be here... but GCC is broken for the time being
1070          * and expects r12 to be callee-saved... */
1071         l.sw    PT_GPR12(r1),r12
1072         l.sw    PT_GPR14(r1),r14
1073         l.sw    PT_GPR16(r1),r16
1074         l.sw    PT_GPR18(r1),r18
1075         l.sw    PT_GPR20(r1),r20
1076         l.sw    PT_GPR22(r1),r22
1077         l.sw    PT_GPR24(r1),r24
1078         l.sw    PT_GPR26(r1),r26
1079         l.sw    PT_GPR28(r1),r28
1080         l.sw    PT_GPR30(r1),r30
1081
1082         l.addi  r11,r10,0                       /* Save old 'current' to 'last' return value*/
1083
1084         /* We use thread_info->ksp for storing the address of the above
1085          * structure so that we can get back to it later... we don't want
1086          * to lose the value of thread_info->ksp, though, so store it as
1087          * pt_regs->sp so that we can easily restore it when we are made
1088          * live again...
1089          */
1090
1091         /* Save the old value of thread_info->ksp as pt_regs->sp */
1092         l.lwz   r29,TI_KSP(r10)
1093         l.sw    PT_SP(r1),r29
1094
1095         /* Swap kernel stack pointers */
1096         l.sw    TI_KSP(r10),r1                  /* Save old stack pointer */
1097         l.or    r10,r4,r0                       /* Set up new current_thread_info */
1098         l.lwz   r1,TI_KSP(r10)                  /* Load new stack pointer */
1099
1100         /* Restore the old value of thread_info->ksp */
1101         l.lwz   r29,PT_SP(r1)
1102         l.sw    TI_KSP(r10),r29
1103
1104         /* ...and restore the registers, except r11 because the return value
1105          * has already been set above.
1106          */
1107         l.lwz   r2,PT_GPR2(r1)
1108         l.lwz   r9,PT_GPR9(r1)
1109         /* No need to restore r10 */
1110         /* ...and do not restore r11 */
1111
1112         /* This is wrong, r12 shouldn't be here... but GCC is broken for the time being
1113          * and expects r12 to be callee-saved... */
1114         l.lwz   r12,PT_GPR12(r1)
1115         l.lwz   r14,PT_GPR14(r1)
1116         l.lwz   r16,PT_GPR16(r1)
1117         l.lwz   r18,PT_GPR18(r1)
1118         l.lwz   r20,PT_GPR20(r1)
1119         l.lwz   r22,PT_GPR22(r1)
1120         l.lwz   r24,PT_GPR24(r1)
1121         l.lwz   r26,PT_GPR26(r1)
1122         l.lwz   r28,PT_GPR28(r1)
1123         l.lwz   r30,PT_GPR30(r1)
1124
1125         /* Unwind stack to pre-switch state */
1126         l.addi  r1,r1,(INT_FRAME_SIZE)
1127
1128         /* Return via the link-register back to where we 'came from', where
1129          * that may be either schedule(), ret_from_fork(), or
1130          * ret_from_kernel_thread().  If we are returning to a new thread,
1131          * we are expected to have set up the arg to schedule_tail already,
1132          * hence we do so here unconditionally:
1133          */
1134         l.lwz   r3,TI_TASK(r3)          /* Load 'prev' as schedule_tail arg */
1135         l.jr    r9
1136          l.nop
1137
1138 /* ==================================================================== */
1139
1140 /* These all use the delay slot for setting the argument register, so the
1141  * jump is always happening after the l.addi instruction.
1142  *
1143  * These are all just wrappers that don't touch the link-register r9, so the
1144  * return from the "real" syscall function will return back to the syscall
1145  * code that did the l.jal that brought us here.
1146  */
1147
1148 /* fork requires that we save all the callee-saved registers because they
1149  * are all effectively clobbered by the call to _switch.  Here we store
1150  * all the registers that aren't touched by the syscall fast path and thus
1151  * weren't saved there.
1152  */
1153
1154 _fork_save_extra_regs_and_call:
1155         l.sw    PT_GPR14(r1),r14
1156         l.sw    PT_GPR16(r1),r16
1157         l.sw    PT_GPR18(r1),r18
1158         l.sw    PT_GPR20(r1),r20
1159         l.sw    PT_GPR22(r1),r22
1160         l.sw    PT_GPR24(r1),r24
1161         l.sw    PT_GPR26(r1),r26
1162         l.jr    r29
1163          l.sw    PT_GPR28(r1),r28
1164
1165 ENTRY(__sys_clone)
1166         l.movhi r29,hi(sys_clone)
1167         l.ori   r29,r29,lo(sys_clone)
1168         l.j     _fork_save_extra_regs_and_call
1169          l.nop
1170
1171 ENTRY(__sys_fork)
1172         l.movhi r29,hi(sys_fork)
1173         l.ori   r29,r29,lo(sys_fork)
1174         l.j     _fork_save_extra_regs_and_call
1175          l.nop
1176
1177 ENTRY(sys_rt_sigreturn)
1178         l.jal   _sys_rt_sigreturn
1179          l.addi r3,r1,0
1180         l.sfne  r30,r0
1181         l.bnf   _no_syscall_trace
1182          l.nop
1183         l.jal   do_syscall_trace_leave
1184          l.addi r3,r1,0
1185 _no_syscall_trace:
1186         l.j     _resume_userspace
1187          l.nop
1188
1189 /* This is a catch-all syscall for atomic instructions for the OpenRISC 1000.
1190  * The functions takes a variable number of parameters depending on which
1191  * particular flavour of atomic you want... parameter 1 is a flag identifying
1192  * the atomic in question.  Currently, this function implements the
1193  * following variants:
1194  *
1195  * XCHG:
1196  *  @flag: 1
1197  *  @ptr1:
1198  *  @ptr2:
1199  * Atomically exchange the values in pointers 1 and 2.
1200  *
1201  */
1202
1203 ENTRY(sys_or1k_atomic)
1204         /* FIXME: This ignores r3 and always does an XCHG */
1205         DISABLE_INTERRUPTS(r17,r19)
1206         l.lwz   r29,0(r4)
1207         l.lwz   r27,0(r5)
1208         l.sw    0(r4),r27
1209         l.sw    0(r5),r29
1210         ENABLE_INTERRUPTS(r17)
1211         l.jr    r9
1212          l.or   r11,r0,r0
1213
1214 /* ============================================================[ EOF ]=== */