target/linux/generic-2.6/patches-2.6.30/029-mips_kexec.patch

   1 This patch updates kernel part of kexec for MIPS platform to support
   2 kdump, 64-bit, SMP and simplify code adaptation to new boards. It does
   3 the following:
   4
   5 - hooks for machine-specific actions are introduced
   6 (_machine_kexec_prepare,
   7   _machine_kexec_shutdown, _machine_crash_shutdown);
   8 - kexec reboot on SMP machine is implemented;
   9 - add boot parameters passing to new kernel (array kexec_args[] is
  10 copied to
  11   registers a0-a3 on reboot );
  12 - crash dump functionality is added (boot kernel with non-default physical
  13   start, parse "crashkernel=..." command line parameter, copy_oldmem_page()
  14   is implemeted to read memory dump after reboot-on-crashi,
  15 crash_setup_regs()
  16   is updated to correctly store registers on crash);
  17
  18 kexec/kdump funtionality was tested on several Cavium Octeon boards
  19 (mips64 SMP). The way we do it was the following:
  20 - _machine_kexec_prepare was find kexec segment with command line and
  21 save it's pointed into internal bootloader structure.
  22 - _machine_kexec_shutdown was used to stop boards IO and make all non-boot
  23 CPUs spin in function relocated_kexec_smp_wait()
  24 - _machine_crash_shutdown just calls default_machine_crash_shutdown()
  25 We tested 1) 'common' kexec reboot (by 'kexec -e'), 2) kexec-on-panic
  26 ('kexec -p ...') and 3) access to/proc/vmcore (with gdb).
  27
  28 Signed-off-by: Maxim Syrchin <[11]msyrchin at ru.mvista.com>
  29 ---
  30 arch/mips/Kconfig                  |   23 +++++++++
  31 arch/mips/Makefile                 |    4 ++
  32 arch/mips/kernel/Makefile          |    3 +-
  33 arch/mips/kernel/crash.c           |   91 ++++++++++++++++++++++++++++++++++
  34 arch/mips/kernel/crash_dump.c      |   96 ++++++++++++++++++++++++++++++++++++
  35 arch/mips/kernel/machine_kexec.c   |   52 ++++++++++++++++++-
  36 arch/mips/kernel/relocate_kernel.S |   93 ++++++++++++++++++++++++++++++++++-
  37 arch/mips/kernel/setup.c           |   10 +++-
  38 arch/mips/include/asm/kexec.h           |   21 ++++++++-
  39 9 files changed, 386 insertions(+), 7 deletions(-)
  40 create mode 100644 arch/mips/kernel/crash.c
  41 create mode 100644 arch/mips/kernel/crash_dump.c
  42
  43 ---
  44  arch/mips/Kconfig                  |   23      23 +    0 -     0 !
  45  arch/mips/Makefile                 |    4      4 +     0 -     0 !
  46  arch/mips/kernel/Makefile          |    3      2 +     1 -     0 !
  47  arch/mips/kernel/crash.c           |   90      90 +    0 -     0 !
  48  arch/mips/kernel/crash_dump.c      |   96      96 +    0 -     0 !
  49  arch/mips/kernel/machine_kexec.c   |   66      60 +    6 -     0 !
  50  arch/mips/kernel/relocate_kernel.S |   96      95 +    1 -     0 !
  51  arch/mips/kernel/setup.c           |   10      9 +     1 -     0 !
  52  arch/mips/include/asm/kexec.h      |   21      20 +    1 -     0 !
  53  9 files changed, 399 insertions(+), 10 deletions(-)
  54
  55 --- a/arch/mips/Kconfig
  56 +++ b/arch/mips/Kconfig
  57 @@ -1966,6 +1966,29 @@ config KEXEC
  58           support.  As of this writing the exact hardware interface is
  59           strongly in flux, so no good recommendation can be made.
  60
  61 +config CRASH_DUMP
  62 +    bool "kernel crash dumps (EXPERIMENTAL)"
  63 +    depends on EXPERIMENTAL
  64 +    help
  65 +      Generate crash dump after being started by kexec.
  66 +          This should be normally only set in special crash dump kernels
  67 +      which are loaded in the main kernel with kexec-tools into
  68 +      a specially reserved region and then later executed after
  69 +      a crash by kdump/kexec. The crash dump kernel must be compiled
  70 +          to a memory address not used by the main kernel or BIOS using
  71 +          PHYSICAL_START.
  72 +
  73 +config PHYSICAL_START
  74 +    hex "Physical address where the kernel is loaded"
  75 +    default "0xffffffff84000000"
  76 +    depends on CRASH_DUMP
  77 +    help
  78 +      This gives the CKSEG0 or KSEG0 address where the kernel is loaded.
  79 +      If you plan to use kernel for capturing the crash dump change
  80 +      this value to start of the reserved region (the "X" value as
  81 +      specified in the "crashkernel=[12]YM at XM" command line boot parameter
  82 +      passed to the panic-ed kernel).
  83 +
  84  config SECCOMP
  85         bool "Enable seccomp to safely compute untrusted bytecode"
  86         depends on PROC_FS
  87 --- a/arch/mips/Makefile
  88 +++ b/arch/mips/Makefile
  89 @@ -603,6 +603,10 @@ else
  90  load-$(CONFIG_CPU_CAVIUM_OCTEON)       += 0xffffffff81100000
  91  endif
  92
  93 +ifdef CONFIG_PHYSICAL_START
  94 +load-y                 = $(CONFIG_PHYSICAL_START)
  95 +endif
  96 +
  97  cflags-y                       += -I$(srctree)/arch/mips/include/asm/mach-generic
  98  drivers-$(CONFIG_PCI)          += arch/mips/pci/
  99
 100 --- a/arch/mips/kernel/Makefile
 101 +++ b/arch/mips/kernel/Makefile
 102 @@ -83,7 +83,8 @@ obj-$(CONFIG_I8253)           += i8253.o
 103
 104  obj-$(CONFIG_GPIO_TXX9)                += gpio_txx9.o
 105
 106 -obj-$(CONFIG_KEXEC)            += machine_kexec.o relocate_kernel.o
 107 +obj-$(CONFIG_KEXEC)        += machine_kexec.o relocate_kernel.o crash.o
 108 +obj-$(CONFIG_CRASH_DUMP)    += crash_dump.o
 109  obj-$(CONFIG_EARLY_PRINTK)     += early_printk.o
 110  obj-$(CONFIG_MIPS_MACHINE)     += mips_machine.o
 111
 112 --- /dev/null
 113 +++ b/arch/mips/kernel/crash.c
 114 @@ -0,0 +1,90 @@
 115 +/*
 116 + * Architecture specific (MIPS) functions for kexec based crash dumps.
 117 + *
 118 + * Copyright (C) 2005, IBM Corp.
 119 + * Copyright (C) 2008, MontaVista Software Inc.
 120 + *
 121 + * This source code is licensed under the GNU General Public License,
 122 + * Version 2.  See the file COPYING for more details.
 123 + *
 124 + */
 125 +
 126 +#undef DEBUG
 127 +
 128 +#include <linux/kernel.h>
 129 +#include <linux/smp.h>
 130 +#include <linux/reboot.h>
 131 +#include <linux/kexec.h>
 132 +#include <linux/bootmem.h>
 133 +#include <linux/crash_dump.h>
 134 +#include <linux/delay.h>
 135 +#include <linux/init.h>
 136 +#include <linux/irq.h>
 137 +#include <linux/types.h>
 138 +#include <linux/sched.h>
 139 +
 140 +
 141 +
 142 +/* This keeps a track of which one is crashing cpu. */
 143 +int crashing_cpu = -1;
 144 +static cpumask_t cpus_in_crash = CPU_MASK_NONE;
 145 +
 146 +#ifdef CONFIG_SMP
 147 +
 148 +void crash_shutdown_secondary(void *ignore)
 149 +{
 150 +    struct pt_regs* regs;
 151 +    int cpu = smp_processor_id();
 152 +
 153 +    regs = task_pt_regs(current);
 154 +    if (!cpu_online(cpu))
 155 +        return;
 156 +
 157 +    local_irq_disable();
 158 +    if (!cpu_isset(cpu, cpus_in_crash))
 159 +        crash_save_cpu(regs, cpu);
 160 +    cpu_set(cpu, cpus_in_crash);
 161 +
 162 +    while(!atomic_read(&kexec_ready_to_reboot)) {
 163 +        cpu_relax();
 164 +    }
 165 +    relocated_kexec_smp_wait(NULL);
 166 +    /* NOTREACHED */
 167 +}
 168 +
 169 +static void crash_kexec_prepare_cpus(void)
 170 +{
 171 +    unsigned int msecs;
 172 +
 173 +    unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
 174 +
 175 +    smp_call_function (crash_shutdown_secondary, NULL, 0);
 176 +    smp_wmb();
 177 +
 178 +    /*
 179 +     * FIXME: Until we will have the way to stop other CPUSs reliabally,
 180 +     * the crash CPU will send an IPI and wait for other CPUs to
 181 +     * respond.
 182 +     * Delay of at least 10 seconds.
 183 +     */
 184 +    printk(KERN_EMERG "Sending IPI to other cpus...\n");
 185 +    msecs = 10000;
 186 +    while ((cpus_weight(cpus_in_crash) < ncpus) && (--msecs > 0)) {
 187 +        cpu_relax();
 188 +        mdelay(1);
 189 +    }
 190 +
 191 +}
 192 +
 193 +#else
 194 +static void crash_kexec_prepare_cpus(void) {}
 195 +#endif
 196 +
 197 +void default_machine_crash_shutdown(struct pt_regs *regs)
 198 +{
 199 +    local_irq_disable();
 200 +    crashing_cpu = smp_processor_id();
 201 +    crash_save_cpu(regs, crashing_cpu);
 202 +    crash_kexec_prepare_cpus();
 203 +    cpu_set(crashing_cpu, cpus_in_crash);
 204 +}
 205 --- /dev/null
 206 +++ b/arch/mips/kernel/crash_dump.c
 207 @@ -0,0 +1,96 @@
 208 +/*
 209 + * Routines for doing kexec-based kdump.
 210 + *
 211 + * Copyright (C) 2005, IBM Corp.
 212 + * Copyright (C) 2008, MontaVista Software Inc.
 213 + *
 214 + * This source code is licensed under the GNU General Public License,
 215 + * Version 2.  See the file COPYING for more details.
 216 + */
 217 +
 218 +#include <linux/highmem.h>
 219 +#include <linux/bootmem.h>
 220 +#include <linux/crash_dump.h>
 221 +#include <asm/uaccess.h>
 222 +
 223 +#ifdef CONFIG_PROC_VMCORE
 224 +static int __init parse_elfcorehdr(char *p)
 225 +{
 226 +    if (p)
 227 +        elfcorehdr_addr = memparse(p, &p);
 228 +    return 1;
 229 +}
 230 +__setup("elfcorehdr=", parse_elfcorehdr);
 231 +#endif
 232 +
 233 +static int __init parse_savemaxmem(char *p)
 234 +{
 235 +    if (p)
 236 +        saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;
 237 +
 238 +    return 1;
 239 +}
 240 +__setup("savemaxmem=", parse_savemaxmem);
 241 +
 242 +
 243 +static void *kdump_buf_page;
 244 +
 245 +/**
 246 + * copy_oldmem_page - copy one page from "oldmem"
 247 + * @pfn: page frame number to be copied
 248 + * @buf: target memory address for the copy; this can be in kernel address
 249 + *    space or user address space (see @userbuf)
 250 + * @csize: number of bytes to copy
 251 + * @offset: offset in bytes into the page (based on pfn) to begin the copy
 252 + * @userbuf: if set, @buf is in user address space, use copy_to_user(),
 253 + *    otherwise @buf is in kernel address space, use memcpy().
 254 + *
 255 + * Copy a page from "oldmem". For this page, there is no pte mapped
 256 + * in the current kernel.
 257 + *
 258 + * Calling copy_to_user() in atomic context is not desirable. Hence first
 259 + * copying the data to a pre-allocated kernel page and then copying to user
 260 + * space in non-atomic context.
 261 + */
 262 +ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
 263 +                               size_t csize, unsigned long offset, int userbuf)
 264 +{
 265 +    void  *vaddr;
 266 +
 267 +    if (!csize)
 268 +        return 0;
 269 +
 270 +    vaddr = kmap_atomic_pfn(pfn, KM_PTE0);
 271 +
 272 +    if (!userbuf) {
 273 +        memcpy(buf, (vaddr + offset), csize);
 274 +        kunmap_atomic(vaddr, KM_PTE0);
 275 +    } else {
 276 +        if (!kdump_buf_page) {
 277 +            printk(KERN_WARNING "Kdump: Kdump buffer page not"
 278 +                " allocated\n");
 279 +            return -EFAULT;
 280 +        }
 281 +        copy_page(kdump_buf_page, vaddr);
 282 +        kunmap_atomic(vaddr, KM_PTE0);
 283 +        if (copy_to_user(buf, (kdump_buf_page + offset), csize))
 284 +            return -EFAULT;
 285 +    }
 286 +
 287 +    return csize;
 288 +}
 289 +
 290 +static int __init kdump_buf_page_init(void)
 291 +{
 292 +    int ret = 0;
 293 +
 294 +    kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL);
 295 +    if (!kdump_buf_page) {
 296 +        printk(KERN_WARNING "Kdump: Failed to allocate kdump buffer"
 297 +             " page\n");
 298 +        ret = -ENOMEM;
 299 +    }
 300 +
 301 +    return ret;
 302 +}
 303 +arch_initcall(kdump_buf_page_init);
 304 --- a/arch/mips/kernel/machine_kexec.c
 305 +++ b/arch/mips/kernel/machine_kexec.c
 306 @@ -19,9 +19,25 @@ extern const size_t relocate_new_kernel_
 307  extern unsigned long kexec_start_address;
 308  extern unsigned long kexec_indirection_page;
 309
 310 +extern unsigned long fw_arg0, fw_arg1, fw_arg2, fw_arg3;
 311 +
 312 +int (*_machine_kexec_prepare)(struct kimage *) = NULL;
 313 +void (*_machine_kexec_shutdown)(void) = NULL;
 314 +void (*_machine_crash_shutdown)(struct pt_regs *regs) = NULL;
 315 +#ifdef CONFIG_SMP
 316 +void (*relocated_kexec_smp_wait) (void *);
 317 +atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
 318 +#endif
 319 +
 320  int
 321  machine_kexec_prepare(struct kimage *kimage)
 322  {
 323 +       kexec_args[0] = fw_arg0;
 324 +       kexec_args[1] = fw_arg1;
 325 +       kexec_args[2] = fw_arg2;
 326 +       kexec_args[3] = fw_arg3;
 327 +       if (_machine_kexec_prepare)
 328 +               return _machine_kexec_prepare(kimage);
 329         return 0;
 330  }
 331
 332 @@ -33,13 +49,18 @@ machine_kexec_cleanup(struct kimage *kim
 333  void
 334  machine_shutdown(void)
 335  {
 336 +    if (_machine_kexec_shutdown)
 337 +        _machine_kexec_shutdown();
 338  }
 339
 340  void
 341  machine_crash_shutdown(struct pt_regs *regs)
 342  {
 343 +    if (_machine_crash_shutdown)
 344 +        _machine_crash_shutdown(regs);
 345 +    else
 346 +        default_machine_crash_shutdown(regs);
 347  }
 348 -
 349  typedef void (*noretfun_t)(void) __attribute__((noreturn));
 350
 351  void
 352 @@ -63,7 +84,7 @@ machine_kexec(struct kimage *image)
 353          * The generic kexec code builds a page list with physical
 354          * addresses. they are directly accessible through KSEG0 (or
 355          * CKSEG0 or XPHYS if on 64bit system), hence the
 356 -        * pys_to_virt() call.
 357 +     * phys_to_virt() call.
 358          */
 359         for (ptr = &image->head; (entry = *ptr) && !(entry &IND_DONE);
 360              ptr = (entry & IND_INDIRECTION) ?
 361 @@ -78,8 +99,39 @@ machine_kexec(struct kimage *image)
 362          */
 363         local_irq_disable();
 364
 365 -       printk("Will call new kernel at %08lx\n", image->start);
 366 -       printk("Bye ...\n");
 367 +       printk(KERN_EMERG "Will call new kernel at %08lx\n", image->start);
 368 +       printk(KERN_EMERG "Bye ...\n");
 369         __flush_cache_all();
 370 -       ((noretfun_t) reboot_code_buffer)();
 371 +#ifdef CONFIG_SMP
 372 +    /* All secondary cpus now may jump to kexec_wait cycle */
 373 +    relocated_kexec_smp_wait = (void *)(reboot_code_buffer +
 374 +        (kexec_smp_wait - relocate_new_kernel));
 375 +    smp_wmb();
 376 +    atomic_set(&kexec_ready_to_reboot,1);
 377 +#endif
 378 +
 379 +       ((noretfun_t) reboot_code_buffer)();
 380 +       printk(KERN_EMERG "Bye ...\n");
 381 +}
 382 +
 383 +/* crashkernel=[13]size at addr specifies the location to reserve for
 384 + * a crash kernel.  By reserving this memory we guarantee
 385 + * that linux never sets it up as a DMA target.
 386 + * Useful for holding code to do something appropriate
 387 + * after a kernel panic.
 388 + */
 389 +static int __init parse_crashkernel_cmdline(char *arg)
 390 +{
 391 +    unsigned long size, base;
 392 +    size = memparse(arg, &arg);
 393 +    if (*arg == '@') {
 394 +        base = memparse(arg+1, &arg);
 395 +        /* FIXME: Do I want a sanity check
 396 +         * to validate the memory range?
 397 +         */
 398 +        crashk_res.start = base;
 399 +        crashk_res.end   = base + size - 1;
 400 +    }
 401 +    return 0;
 402  }
 403 +early_param("crashkernel", parse_crashkernel_cmdline);
 404 --- a/arch/mips/kernel/relocate_kernel.S
 405 +++ b/arch/mips/kernel/relocate_kernel.S
 406 @@ -14,7 +14,13 @@
 407  #include <asm/stackframe.h>
 408  #include <asm/addrspace.h>
 409
 410 +
 411  LEAF(relocate_new_kernel)
 412 +     PTR_L a0,    arg0
 413 +     PTR_L a1,    arg1
 414 +     PTR_L a2,    arg2
 415 +     PTR_L a3,    arg3
 416 +
 417         PTR_L           s0, kexec_indirection_page
 418         PTR_L           s1, kexec_start_address
 419
 420 @@ -26,7 +32,6 @@ process_entry:
 421         and             s3, s2, 0x1
 422         beq             s3, zero, 1f
 423         and             s4, s2, ~0x1    /* store destination addr in s4 */
 424 -       move            a0, s4
 425         b               process_entry
 426
 427  1:
 428 @@ -40,6 +45,7 @@ process_entry:
 429         /* done page */
 430         and             s3, s2, 0x4
 431         beq             s3, zero, 1f
 432 +       nop
 433         b               done
 434  1:
 435         /* source page */
 436 @@ -56,14 +62,102 @@ copy_word:
 437         PTR_ADD         s2, s2, SZREG
 438         LONG_SUB        s6, s6, 1
 439         beq             s6, zero, process_entry
 440 +       nop
 441         b               copy_word
 442 +       nop
 443         b               process_entry
 444
 445  done:
 446 +#ifdef CONFIG_SMP
 447 +    /* kexec_flag reset is signal to other CPUs what kernel
 448 +        was moved to it's location. Note - we need relocated address
 449 +        of kexec_flag.  */
 450 +
 451 +     bal        1f
 452 + 1:     move        t1,ra;
 453 +     PTR_LA        t2,1b
 454 +     PTR_LA        t0,kexec_flag
 455 +     PTR_SUB        t0,t0,t2;
 456 +     PTR_ADD        t0,t1,t0;
 457 +     LONG_S        zero,(t0)
 458 +#endif
 459 +
 460 +     /* Some platforms need I-cache to be flushed before
 461 +     * jumping to new kernel.
 462 +      */
 463 +
 464         /* jump to kexec_start_address */
 465         j               s1
 466         END(relocate_new_kernel)
 467
 468 +#ifdef CONFIG_SMP
 469 +/*
 470 + * Other CPUs should wait until code is relocated and
 471 + * then start at entry point.
 472 + */
 473 +LEAF(kexec_smp_wait)
 474 +    PTR_L        a0, s_arg0
 475 +    PTR_L        a1, s_arg1
 476 +    PTR_L        a2, s_arg2
 477 +    PTR_L        a3, s_arg3
 478 +    PTR_L        s1, kexec_start_address
 479 +
 480 +    /* Non-relocated address works for args and kexec_start_address ( old
 481 +     * kernel is not overwritten). But we need relocated address of
 482 +     * kexec_flag.
 483 +     */
 484 +
 485 +    bal        1f
 486 +1:    move        t1,ra;
 487 +    PTR_LA        t2,1b
 488 +    PTR_LA        t0,kexec_flag
 489 +    PTR_SUB        t0,t0,t2;
 490 +    PTR_ADD        t0,t1,t0;
 491 +
 492 +1:    LONG_L        s0, (t0)
 493 +    bne        s0, zero,1b
 494 +
 495 +    j        s1
 496 +    END(kexec_smp_wait)
 497 +#endif
 498 +
 499 +
 500 +#ifdef __mips64
 501 +       /* all PTR's must be aligned to 8 byte in 64-bit mode */
 502 +       .align  3
 503 +#endif
 504 +
 505 +/* All parameters to new kernel are passed in registers a0-a3.
 506 + * kexec_args[0..3] are uses to prepare register values.
 507 + */
 508 +
 509 +kexec_args:
 510 +    EXPORT(kexec_args)
 511 +arg0:    PTR        0x0
 512 +arg1:    PTR        0x0
 513 +arg2:    PTR        0x0
 514 +arg3:    PTR        0x0
 515 +    .size    kexec_args,PTRSIZE*4
 516 +
 517 +#ifdef CONFIG_SMP
 518 +/*
 519 + * Secondary CPUs may have different kernel parameters in
 520 + * their registers a0-a3. secondary_kexec_args[0..3] are used
 521 + * to prepare register values.
 522 + */
 523 +secondary_kexec_args:
 524 +    EXPORT(secondary_kexec_args)
 525 +s_arg0:    PTR        0x0
 526 +s_arg1:    PTR        0x0
 527 +s_arg2:    PTR        0x0
 528 +s_arg3:    PTR        0x0
 529 +    .size    secondary_kexec_args,PTRSIZE*4
 530 +kexec_flag:
 531 +    LONG        0x1
 532 +
 533 +#endif
 534 +
 535 +
 536  kexec_start_address:
 537         EXPORT(kexec_start_address)
 538         PTR             0x0
 539 --- a/arch/mips/kernel/setup.c
 540 +++ b/arch/mips/kernel/setup.c
 541 @@ -21,7 +21,7 @@
 542  #include <linux/console.h>
 543  #include <linux/pfn.h>
 544  #include <linux/debugfs.h>
 545 -
 546 +#include <linux/kexec.h>
 547  #include <asm/addrspace.h>
 548  #include <asm/bootinfo.h>
 549  #include <asm/bugs.h>
 550 @@ -489,6 +489,11 @@ static void __init arch_mem_init(char **
 551         }
 552
 553         bootmem_init();
 554 +#ifdef CONFIG_CRASH_DUMP
 555 +    if (crashk_res.start != crashk_res.end)
 556 +        reserve_bootmem(crashk_res.start,
 557 +                crashk_res.end - crashk_res.start + 1);
 558 +#endif
 559         sparse_init();
 560         paging_init();
 561  }
 562 @@ -543,6 +548,9 @@ static void __init resource_init(void)
 563                  */
 564                 request_resource(res, &code_resource);
 565                 request_resource(res, &data_resource);
 566 +#ifdef CONFIG_KEXEC
 567 +        request_resource(res, &crashk_res);
 568 +#endif
 569         }
 570  }
 571
 572 --- a/arch/mips/include/asm/kexec.h
 573 +++ b/arch/mips/include/asm/kexec.h
 574 @@ -9,6 +9,8 @@
 575  #ifndef _MIPS_KEXEC
 576  # define _MIPS_KEXEC
 577
 578 +#include <asm/stacktrace.h>
 579 +
 580  /* Maximum physical address we can use pages from */
 581  #define KEXEC_SOURCE_MEMORY_LIMIT (0x20000000)
 582  /* Maximum address we can reach in physical address mode */
 583 @@ -24,7 +26,24 @@
 584  static inline void crash_setup_regs(struct pt_regs *newregs,
 585                                     struct pt_regs *oldregs)
 586  {
 587 -       /* Dummy implementation for now */
 588 +    if (oldregs)
 589 +        memcpy(newregs, oldregs, sizeof(*newregs));
 590 +    else
 591 +        prepare_frametrace(newregs);
 592  }
 593
 594 +#ifdef CONFIG_KEXEC
 595 +struct kimage;
 596 +extern unsigned long kexec_args[4];
 597 +extern int (*_machine_kexec_prepare)(struct kimage *);
 598 +extern void (*_machine_kexec_shutdown)(void);
 599 +extern void (*_machine_crash_shutdown)(struct pt_regs *regs);
 600 +extern void default_machine_crash_shutdown(struct pt_regs *regs);
 601 +#ifdef CONFIG_SMP
 602 +extern const unsigned char kexec_smp_wait[];
 603 +extern unsigned long secondary_kexec_args[4];
 604 +extern void (*relocated_kexec_smp_wait) (void *);
 605 +extern atomic_t kexec_ready_to_reboot;
 606 +#endif
 607 +#endif
 608  #endif /* !_MIPS_KEXEC */