The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/dump_machdep.c

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    1 /*-
    2  * Copyright (c) 2002 Marcel Moolenaar
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  *
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: releng/8.1/sys/i386/i386/dump_machdep.c 199583 2009-11-20 15:27:52Z jhb $");
   29 
   30 #include <sys/param.h>
   31 #include <sys/systm.h>
   32 #include <sys/conf.h>
   33 #include <sys/cons.h>
   34 #include <sys/sysctl.h>
   35 #include <sys/kernel.h>
   36 #include <sys/kerneldump.h>
   37 #include <vm/vm.h>
   38 #include <vm/pmap.h>
   39 #include <machine/elf.h>
   40 #include <machine/md_var.h>
   41 
   42 CTASSERT(sizeof(struct kerneldumpheader) == 512);
   43 
   44 int do_minidump = 1;
   45 TUNABLE_INT("debug.minidump", &do_minidump);
   46 SYSCTL_INT(_debug, OID_AUTO, minidump, CTLFLAG_RW, &do_minidump, 0,
   47     "Enable mini crash dumps");
   48 
   49 /*
   50  * Don't touch the first SIZEOF_METADATA bytes on the dump device. This
   51  * is to protect us from metadata and to protect metadata from us.
   52  */
   53 #define SIZEOF_METADATA         (64*1024)
   54 
   55 #define MD_ALIGN(x)     (((off_t)(x) + PAGE_MASK) & ~PAGE_MASK)
   56 #define DEV_ALIGN(x)    (((off_t)(x) + (DEV_BSIZE-1)) & ~(DEV_BSIZE-1))
   57 
   58 struct md_pa {
   59         vm_paddr_t md_start;
   60         vm_paddr_t md_size;
   61 };
   62 
   63 typedef int callback_t(struct md_pa *, int, void *);
   64 
   65 static struct kerneldumpheader kdh;
   66 static off_t dumplo, fileofs;
   67 
   68 /* Handle buffered writes. */
   69 static char buffer[DEV_BSIZE];
   70 static size_t fragsz;
   71 
   72 /* 20 phys_avail entry pairs correspond to 10 md_pa's */
   73 static struct md_pa dump_map[10];
   74 
   75 static void
   76 md_pa_init(void)
   77 {
   78         int n, idx;
   79 
   80         bzero(dump_map, sizeof(dump_map));
   81         for (n = 0; n < sizeof(dump_map) / sizeof(dump_map[0]); n++) {
   82                 idx = n * 2;
   83                 if (dump_avail[idx] == 0 && dump_avail[idx + 1] == 0)
   84                         break;
   85                 dump_map[n].md_start = dump_avail[idx];
   86                 dump_map[n].md_size = dump_avail[idx + 1] - dump_avail[idx];
   87         }
   88 }
   89 
   90 static struct md_pa *
   91 md_pa_first(void)
   92 {
   93 
   94         return (&dump_map[0]);
   95 }
   96 
   97 static struct md_pa *
   98 md_pa_next(struct md_pa *mdp)
   99 {
  100 
  101         mdp++;
  102         if (mdp->md_size == 0)
  103                 mdp = NULL;
  104         return (mdp);
  105 }
  106 
  107 static int
  108 buf_write(struct dumperinfo *di, char *ptr, size_t sz)
  109 {
  110         size_t len;
  111         int error;
  112 
  113         while (sz) {
  114                 len = DEV_BSIZE - fragsz;
  115                 if (len > sz)
  116                         len = sz;
  117                 bcopy(ptr, buffer + fragsz, len);
  118                 fragsz += len;
  119                 ptr += len;
  120                 sz -= len;
  121                 if (fragsz == DEV_BSIZE) {
  122                         error = dump_write(di, buffer, 0, dumplo,
  123                             DEV_BSIZE);
  124                         if (error)
  125                                 return error;
  126                         dumplo += DEV_BSIZE;
  127                         fragsz = 0;
  128                 }
  129         }
  130 
  131         return (0);
  132 }
  133 
  134 static int
  135 buf_flush(struct dumperinfo *di)
  136 {
  137         int error;
  138 
  139         if (fragsz == 0)
  140                 return (0);
  141 
  142         error = dump_write(di, buffer, 0, dumplo, DEV_BSIZE);
  143         dumplo += DEV_BSIZE;
  144         fragsz = 0;
  145         return (error);
  146 }
  147 
  148 #define PG2MB(pgs) ((pgs + (1 << 8) - 1) >> 8)
  149 
  150 static int
  151 cb_dumpdata(struct md_pa *mdp, int seqnr, void *arg)
  152 {
  153         struct dumperinfo *di = (struct dumperinfo*)arg;
  154         vm_paddr_t a, pa;
  155         void *va;
  156         uint64_t pgs;
  157         size_t counter, sz, chunk;
  158         int i, c, error, twiddle;
  159         u_int maxdumppgs;
  160 
  161         error = 0;      /* catch case in which chunk size is 0 */
  162         counter = 0;    /* Update twiddle every 16MB */
  163         twiddle = 0;
  164         va = 0;
  165         pgs = mdp->md_size / PAGE_SIZE;
  166         pa = mdp->md_start;
  167         maxdumppgs = min(di->maxiosize / PAGE_SIZE, MAXDUMPPGS);
  168         if (maxdumppgs == 0)    /* seatbelt */
  169                 maxdumppgs = 1;
  170 
  171         printf("  chunk %d: %lldMB (%lld pages)", seqnr, PG2MB(pgs), pgs);
  172 
  173         while (pgs) {
  174                 chunk = pgs;
  175                 if (chunk > maxdumppgs)
  176                         chunk = maxdumppgs;
  177                 sz = chunk << PAGE_SHIFT;
  178                 counter += sz;
  179                 if (counter >> 24) {
  180                         printf(" %lld", PG2MB(pgs));
  181                         counter &= (1<<24) - 1;
  182                 }
  183                 for (i = 0; i < chunk; i++) {
  184                         a = pa + i * PAGE_SIZE;
  185                         va = pmap_kenter_temporary(trunc_page(a), i);
  186                 }
  187                 error = dump_write(di, va, 0, dumplo, sz);
  188                 if (error)
  189                         break;
  190                 dumplo += sz;
  191                 pgs -= chunk;
  192                 pa += sz;
  193 
  194                 /* Check for user abort. */
  195                 c = cncheckc();
  196                 if (c == 0x03)
  197                         return (ECANCELED);
  198                 if (c != -1)
  199                         printf(" (CTRL-C to abort) ");
  200         }
  201         printf(" ... %s\n", (error) ? "fail" : "ok");
  202         return (error);
  203 }
  204 
  205 static int
  206 cb_dumphdr(struct md_pa *mdp, int seqnr, void *arg)
  207 {
  208         struct dumperinfo *di = (struct dumperinfo*)arg;
  209         Elf_Phdr phdr;
  210         uint64_t size;
  211         int error;
  212 
  213         size = mdp->md_size;
  214         bzero(&phdr, sizeof(phdr));
  215         phdr.p_type = PT_LOAD;
  216         phdr.p_flags = PF_R;                    /* XXX */
  217         phdr.p_offset = fileofs;
  218         phdr.p_vaddr = mdp->md_start;
  219         phdr.p_paddr = mdp->md_start;
  220         phdr.p_filesz = size;
  221         phdr.p_memsz = size;
  222         phdr.p_align = PAGE_SIZE;
  223 
  224         error = buf_write(di, (char*)&phdr, sizeof(phdr));
  225         fileofs += phdr.p_filesz;
  226         return (error);
  227 }
  228 
  229 static int
  230 cb_size(struct md_pa *mdp, int seqnr, void *arg)
  231 {
  232         uint64_t *sz = (uint64_t*)arg;
  233 
  234         *sz += (uint64_t)mdp->md_size;
  235         return (0);
  236 }
  237 
  238 static int
  239 foreach_chunk(callback_t cb, void *arg)
  240 {
  241         struct md_pa *mdp;
  242         int error, seqnr;
  243 
  244         seqnr = 0;
  245         mdp = md_pa_first();
  246         while (mdp != NULL) {
  247                 error = (*cb)(mdp, seqnr++, arg);
  248                 if (error)
  249                         return (-error);
  250                 mdp = md_pa_next(mdp);
  251         }
  252         return (seqnr);
  253 }
  254 
  255 void
  256 dumpsys(struct dumperinfo *di)
  257 {
  258         Elf_Ehdr ehdr;
  259         uint64_t dumpsize;
  260         off_t hdrgap;
  261         size_t hdrsz;
  262         int error;
  263 
  264         if (do_minidump) {
  265                 minidumpsys(di);
  266                 return;
  267         }
  268         bzero(&ehdr, sizeof(ehdr));
  269         ehdr.e_ident[EI_MAG0] = ELFMAG0;
  270         ehdr.e_ident[EI_MAG1] = ELFMAG1;
  271         ehdr.e_ident[EI_MAG2] = ELFMAG2;
  272         ehdr.e_ident[EI_MAG3] = ELFMAG3;
  273         ehdr.e_ident[EI_CLASS] = ELF_CLASS;
  274 #if BYTE_ORDER == LITTLE_ENDIAN
  275         ehdr.e_ident[EI_DATA] = ELFDATA2LSB;
  276 #else
  277         ehdr.e_ident[EI_DATA] = ELFDATA2MSB;
  278 #endif
  279         ehdr.e_ident[EI_VERSION] = EV_CURRENT;
  280         ehdr.e_ident[EI_OSABI] = ELFOSABI_STANDALONE;   /* XXX big picture? */
  281         ehdr.e_type = ET_CORE;
  282         ehdr.e_machine = EM_386;
  283         ehdr.e_phoff = sizeof(ehdr);
  284         ehdr.e_flags = 0;
  285         ehdr.e_ehsize = sizeof(ehdr);
  286         ehdr.e_phentsize = sizeof(Elf_Phdr);
  287         ehdr.e_shentsize = sizeof(Elf_Shdr);
  288 
  289         md_pa_init();
  290 
  291         /* Calculate dump size. */
  292         dumpsize = 0L;
  293         ehdr.e_phnum = foreach_chunk(cb_size, &dumpsize);
  294         hdrsz = ehdr.e_phoff + ehdr.e_phnum * ehdr.e_phentsize;
  295         fileofs = MD_ALIGN(hdrsz);
  296         dumpsize += fileofs;
  297         hdrgap = fileofs - DEV_ALIGN(hdrsz);
  298 
  299         /* Determine dump offset on device. */
  300         if (di->mediasize < SIZEOF_METADATA + dumpsize + sizeof(kdh) * 2) {
  301                 error = ENOSPC;
  302                 goto fail;
  303         }
  304         dumplo = di->mediaoffset + di->mediasize - dumpsize;
  305         dumplo -= sizeof(kdh) * 2;
  306 
  307         mkdumpheader(&kdh, KERNELDUMPMAGIC, KERNELDUMP_I386_VERSION, dumpsize, di->blocksize);
  308 
  309         printf("Dumping %llu MB (%d chunks)\n", (long long)dumpsize >> 20,
  310             ehdr.e_phnum);
  311 
  312         /* Dump leader */
  313         error = dump_write(di, &kdh, 0, dumplo, sizeof(kdh));
  314         if (error)
  315                 goto fail;
  316         dumplo += sizeof(kdh);
  317 
  318         /* Dump ELF header */
  319         error = buf_write(di, (char*)&ehdr, sizeof(ehdr));
  320         if (error)
  321                 goto fail;
  322 
  323         /* Dump program headers */
  324         error = foreach_chunk(cb_dumphdr, di);
  325         if (error < 0)
  326                 goto fail;
  327         buf_flush(di);
  328 
  329         /*
  330          * All headers are written using blocked I/O, so we know the
  331          * current offset is (still) block aligned. Skip the alignement
  332          * in the file to have the segment contents aligned at page
  333          * boundary. We cannot use MD_ALIGN on dumplo, because we don't
  334          * care and may very well be unaligned within the dump device.
  335          */
  336         dumplo += hdrgap;
  337 
  338         /* Dump memory chunks (updates dumplo) */
  339         error = foreach_chunk(cb_dumpdata, di);
  340         if (error < 0)
  341                 goto fail;
  342 
  343         /* Dump trailer */
  344         error = dump_write(di, &kdh, 0, dumplo, sizeof(kdh));
  345         if (error)
  346                 goto fail;
  347 
  348         /* Signal completion, signoff and exit stage left. */
  349         dump_write(di, NULL, 0, 0, 0);
  350         printf("\nDump complete\n");
  351         return;
  352 
  353  fail:
  354         if (error < 0)
  355                 error = -error;
  356 
  357         if (error == ECANCELED)
  358                 printf("\nDump aborted\n");
  359         else if (error == ENOSPC)
  360                 printf("\nDump failed. Partition too small.\n");
  361         else
  362                 printf("\n** DUMP FAILED (ERROR %d) **\n", error);
  363 }

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