kern_dump.c

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/*-
 * Copyright (c) 2002 Marcel Moolenaar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
 
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/cons.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/kerneldump.h>
#include <sys/malloc.h>
#include <sys/msgbuf.h>
#include <sys/proc.h>
#include <sys/watchdog.h>
 
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_page.h>
#include <vm/vm_phys.h>
#include <vm/vm_dumpset.h>
#include <vm/pmap.h>
 
#include <machine/dump.h>
#include <machine/elf.h>
#include <machine/md_var.h>
#include <machine/pcb.h>
 
CTASSERT(sizeof(struct kerneldumpheader) == 512);
 
#define MD_ALIGN(x)     roundup2((off_t)(x), PAGE_SIZE)
 
/* Handle buffered writes. */
static size_t fragsz;
 
struct dump_pa dump_map[DUMPSYS_MD_PA_NPAIRS];
 
#if !defined(__powerpc__)
void
dumpsys_gen_pa_init(void)
{
        int n, idx;
 
        bzero(dump_map, sizeof(dump_map));
        for (n = 0; n < nitems(dump_map); n++) {
                idx = n * 2;
                if (dump_avail[idx] == 0 && dump_avail[idx + 1] == 0)
                        break;
                dump_map[n].pa_start = dump_avail[idx];
                dump_map[n].pa_size = dump_avail[idx + 1] - dump_avail[idx];
        }
}
#endif
 
struct dump_pa *
dumpsys_gen_pa_next(struct dump_pa *mdp)
{
 
        if (mdp == NULL)
                return (&dump_map[0]);
 
        mdp++;
        if (mdp->pa_size == 0)
                mdp = NULL;
        return (mdp);
}
 
void
dumpsys_gen_wbinv_all(void)
{
 
}
 
void
dumpsys_gen_unmap_chunk(vm_paddr_t pa __unused, size_t chunk __unused,
    void *va __unused)
{
 
}
 
int
dumpsys_gen_write_aux_headers(struct dumperinfo *di)
{
 
        return (0);
}
 
int
dumpsys_buf_seek(struct dumperinfo *di, size_t sz)
{
        static uint8_t buf[DEV_BSIZE];
        size_t nbytes;
        int error;
 
        bzero(buf, sizeof(buf));
 
        while (sz > 0) {
                nbytes = MIN(sz, sizeof(buf));
 
                error = dump_append(di, buf, 0, nbytes);
                if (error)
                        return (error);
                sz -= nbytes;
        }
 
        return (0);
}
 
int
dumpsys_buf_write(struct dumperinfo *di, char *ptr, size_t sz)
{
        size_t len;
        int error;
 
        while (sz) {
                len = di->blocksize - fragsz;
                if (len > sz)
                        len = sz;
                memcpy((char *)di->blockbuf + fragsz, ptr, len);
                fragsz += len;
                ptr += len;
                sz -= len;
                if (fragsz == di->blocksize) {
                        error = dump_append(di, di->blockbuf, 0, di->blocksize);
                        if (error)
                                return (error);
                        fragsz = 0;
                }
        }
        return (0);
}
 
int
dumpsys_buf_flush(struct dumperinfo *di)
{
        int error;
 
        if (fragsz == 0)
                return (0);
 
        error = dump_append(di, di->blockbuf, 0, di->blocksize);
        fragsz = 0;
        return (error);
}
 
CTASSERT(PAGE_SHIFT < 20);
#define PG2MB(pgs) ((pgs + (1 << (20 - PAGE_SHIFT)) - 1) >> (20 - PAGE_SHIFT))
 
int
dumpsys_cb_dumpdata(struct dump_pa *mdp, int seqnr, void *arg)
{
        struct dumperinfo *di = (struct dumperinfo*)arg;
        vm_paddr_t pa;
        void *va;
        uint64_t pgs;
        size_t counter, sz, chunk;
        int c, error;
        u_int maxdumppgs;
 
        error = 0;      /* catch case in which chunk size is 0 */
        counter = 0;    /* Update twiddle every 16MB */
        va = NULL;
        pgs = mdp->pa_size / PAGE_SIZE;
        pa = mdp->pa_start;
        maxdumppgs = min(di->maxiosize / PAGE_SIZE, MAXDUMPPGS);
        if (maxdumppgs == 0)    /* seatbelt */
                maxdumppgs = 1;
 
        printf("  chunk %d: %juMB (%ju pages)", seqnr, (uintmax_t)PG2MB(pgs),
            (uintmax_t)pgs);
 
        dumpsys_wbinv_all();
        while (pgs) {
                chunk = pgs;
                if (chunk > maxdumppgs)
                        chunk = maxdumppgs;
                sz = chunk << PAGE_SHIFT;
                counter += sz;
                if (counter >> 24) {
                        printf(" %ju", (uintmax_t)PG2MB(pgs));
                        counter &= (1 << 24) - 1;
                }
 
                dumpsys_map_chunk(pa, chunk, &va);
                wdog_kern_pat(WD_LASTVAL);
 
                error = dump_append(di, va, 0, sz);
                dumpsys_unmap_chunk(pa, chunk, va);
                if (error)
                        break;
                pgs -= chunk;
                pa += sz;
 
                /* Check for user abort. */
                c = cncheckc();
                if (c == 0x03)
                        return (ECANCELED);
                if (c != -1)
                        printf(" (CTRL-C to abort) ");
        }
        printf(" ... %s\n", (error) ? "fail" : "ok");
        return (error);
}
 
int
dumpsys_foreach_chunk(dumpsys_callback_t cb, void *arg)
{
        struct dump_pa *mdp;
        int error, seqnr;
 
        seqnr = 0;
        mdp = dumpsys_pa_next(NULL);
        while (mdp != NULL) {
                error = (*cb)(mdp, seqnr++, arg);
                if (error)
                        return (-error);
                mdp = dumpsys_pa_next(mdp);
        }
        return (seqnr);
}
 
static off_t fileofs;
 
static int
cb_dumphdr(struct dump_pa *mdp, int seqnr, void *arg)
{
        struct dumperinfo *di = (struct dumperinfo*)arg;
        Elf_Phdr phdr;
        uint64_t size;
        int error;
 
        size = mdp->pa_size;
        bzero(&phdr, sizeof(phdr));
        phdr.p_type = PT_LOAD;
        phdr.p_flags = PF_R;                    /* XXX */
        phdr.p_offset = fileofs;
#ifdef __powerpc__
        phdr.p_vaddr = (do_minidump? mdp->pa_start : ~0L);
        phdr.p_paddr = (do_minidump? ~0L : mdp->pa_start);
#else
        phdr.p_vaddr = mdp->pa_start;
        phdr.p_paddr = mdp->pa_start;
#endif
        phdr.p_filesz = size;
        phdr.p_memsz = size;
        phdr.p_align = PAGE_SIZE;
 
        error = dumpsys_buf_write(di, (char*)&phdr, sizeof(phdr));
        fileofs += phdr.p_filesz;
        return (error);
}
 
static int
cb_size(struct dump_pa *mdp, int seqnr, void *arg)
{
        uint64_t *sz;
 
        sz = (uint64_t *)arg;
        *sz += (uint64_t)mdp->pa_size;
        return (0);
}
 
int
dumpsys_generic(struct dumperinfo *di)
{
        static struct kerneldumpheader kdh;
        Elf_Ehdr ehdr;
        uint64_t dumpsize;
        off_t hdrgap;
        size_t hdrsz;
        int error;
 
#if MINIDUMP_PAGE_TRACKING == 1
        if (do_minidump)
                return (minidumpsys(di, false));
#endif
 
        bzero(&ehdr, sizeof(ehdr));
        ehdr.e_ident[EI_MAG0] = ELFMAG0;
        ehdr.e_ident[EI_MAG1] = ELFMAG1;
        ehdr.e_ident[EI_MAG2] = ELFMAG2;
        ehdr.e_ident[EI_MAG3] = ELFMAG3;
        ehdr.e_ident[EI_CLASS] = ELF_CLASS;
#if BYTE_ORDER == LITTLE_ENDIAN
        ehdr.e_ident[EI_DATA] = ELFDATA2LSB;
#else
        ehdr.e_ident[EI_DATA] = ELFDATA2MSB;
#endif
        ehdr.e_ident[EI_VERSION] = EV_CURRENT;
        ehdr.e_ident[EI_OSABI] = ELFOSABI_STANDALONE;   /* XXX big picture? */
        ehdr.e_type = ET_CORE;
        ehdr.e_machine = EM_VALUE;
        ehdr.e_phoff = sizeof(ehdr);
        ehdr.e_flags = 0;
        ehdr.e_ehsize = sizeof(ehdr);
        ehdr.e_phentsize = sizeof(Elf_Phdr);
        ehdr.e_shentsize = sizeof(Elf_Shdr);
 
        dumpsys_pa_init();
 
        /* Calculate dump size. */
        dumpsize = 0L;
        ehdr.e_phnum = dumpsys_foreach_chunk(cb_size, &dumpsize) +
            DUMPSYS_NUM_AUX_HDRS;
        hdrsz = ehdr.e_phoff + ehdr.e_phnum * ehdr.e_phentsize;
        fileofs = MD_ALIGN(hdrsz);
        dumpsize += fileofs;
        hdrgap = fileofs - roundup2((off_t)hdrsz, di->blocksize);
 
        dump_init_header(di, &kdh, KERNELDUMPMAGIC, KERNELDUMP_ARCH_VERSION,
            dumpsize);
 
        error = dump_start(di, &kdh);
        if (error != 0)
                goto fail;
 
        printf("Dumping %ju MB (%d chunks)\n", (uintmax_t)dumpsize >> 20,
            ehdr.e_phnum - DUMPSYS_NUM_AUX_HDRS);
 
        /* Dump ELF header */
        error = dumpsys_buf_write(di, (char*)&ehdr, sizeof(ehdr));
        if (error)
                goto fail;
 
        /* Dump program headers */
        error = dumpsys_foreach_chunk(cb_dumphdr, di);
        if (error < 0)
                goto fail;
        error = dumpsys_write_aux_headers(di);
        if (error < 0)
                goto fail;
        dumpsys_buf_flush(di);
 
        /*
         * All headers are written using blocked I/O, so we know the
         * current offset is (still) block aligned. Skip the alignement
         * in the file to have the segment contents aligned at page
         * boundary.
         */
        error = dumpsys_buf_seek(di, (size_t)hdrgap);
        if (error)
                goto fail;
 
        /* Dump memory chunks. */
        error = dumpsys_foreach_chunk(dumpsys_cb_dumpdata, di);
        if (error < 0)
                goto fail;
 
        error = dump_finish(di, &kdh);
        if (error != 0)
                goto fail;
 
        printf("\nDump complete\n");
        return (0);
 
 fail:
        if (error < 0)
                error = -error;
 
        if (error == ECANCELED)
                printf("\nDump aborted\n");
        else if (error == E2BIG || error == ENOSPC)
                printf("\nDump failed. Partition too small.\n");
        else
                printf("\n** DUMP FAILED (ERROR %d) **\n", error);
        return (error);
}
 
#if MINIDUMP_PAGE_TRACKING == 1
 
/* Minidump progress bar */
static struct {
        const int min_per;
        const int max_per;
        bool visited;
} progress_track[10] = {
        {  0,  10, false},
        { 10,  20, false},
        { 20,  30, false},
        { 30,  40, false},
        { 40,  50, false},
        { 50,  60, false},
        { 60,  70, false},
        { 70,  80, false},
        { 80,  90, false},
        { 90, 100, false}
};
 
static uint64_t dumpsys_pb_size;
static uint64_t dumpsys_pb_remaining;
static uint64_t dumpsys_pb_check;
 
/* Reset the progress bar for a dump of dumpsize. */
void
dumpsys_pb_init(uint64_t dumpsize)
{
        int i;
 
        dumpsys_pb_size = dumpsys_pb_remaining = dumpsize;
        dumpsys_pb_check = 0;
 
        for (i = 0; i < nitems(progress_track); i++)
                progress_track[i].visited = false;
}
 
/*
 * Update the progress according to the delta bytes that were written out.
 * Check and print the progress percentage.
 */
void
dumpsys_pb_progress(size_t delta)
{
        int sofar, i;
 
        dumpsys_pb_remaining -= delta;
        dumpsys_pb_check += delta;
 
        /*
         * To save time while dumping, only loop through progress_track
         * occasionally.
         */
        if ((dumpsys_pb_check >> DUMPSYS_PB_CHECK_BITS) == 0)
                return;
        else
                dumpsys_pb_check &= (1 << DUMPSYS_PB_CHECK_BITS) - 1;
 
        sofar = 100 - ((dumpsys_pb_remaining * 100) / dumpsys_pb_size);
        for (i = 0; i < nitems(progress_track); i++) {
                if (sofar < progress_track[i].min_per ||
                    sofar > progress_track[i].max_per)
                        continue;
                if (!progress_track[i].visited) {
                        progress_track[i].visited = true;
                        printf("..%d%%", sofar);
                }
                break;
        }
}
 
int
minidumpsys(struct dumperinfo *di, bool livedump)
{
        struct minidumpstate state;
        struct msgbuf mb_copy;
        char *msg_ptr;
        size_t sz;
        int error;
 
        if (livedump) {
                KASSERT(!dumping, ("live dump invoked from incorrect context"));
 
                /*
                 * Before invoking cpu_minidumpsys() on the live system, we
                 * must snapshot some required global state: the message
                 * buffer, and the page dump bitset. They may be modified at
                 * any moment, so for the sake of the live dump it is best to
                 * have an unchanging snapshot to work with. Both are included
                 * as part of the dump and consumed by userspace tools.
                 *
                 * Other global state important to the minidump code is the
                 * dump_avail array and the kernel's page tables, but snapshots
                 * are not taken of these. For one, dump_avail[] is expected
                 * not to change after boot. Snapshotting the kernel page
                 * tables would involve an additional walk, so this is avoided
                 * too.
                 *
                 * This means live dumps are best effort, and the result may or
                 * may not be usable; there are no guarantees about the
                 * consistency of the dump's contents. Any of the following
                 * (and likely more) may affect the live dump:
                 *
                 *  - Data may be modified, freed, or remapped during the
                 *    course of the dump, such that the contents written out
                 *    are partially or entirely unrecognizable. This means
                 *    valid references may point to destroyed/mangled objects,
                 *    and vice versa.
                 *
                 *  - The dumped context of any threads that ran during the
                 *    dump process may be unreliable.
                 *
                 *  - The set of kernel page tables included in the dump likely
                 *    won't correspond exactly to the copy of the dump bitset.
                 *    This means some pages will be dumped without any way to
                 *    locate them, and some pages may not have been dumped
                 *    despite appearing as if they should.
                 */
                msg_ptr = malloc(msgbufsize, M_TEMP, M_WAITOK);
                msgbuf_duplicate(msgbufp, &mb_copy, msg_ptr);
                state.msgbufp = &mb_copy;
 
                sz = BITSET_SIZE(vm_page_dump_pages);
                state.dump_bitset = malloc(sz, M_TEMP, M_WAITOK);
                BIT_COPY_STORE_REL(sz, vm_page_dump, state.dump_bitset);
        } else {
                KASSERT(dumping, ("minidump invoked outside of doadump()"));
 
                /* Use the globals. */
                state.msgbufp = msgbufp;
                state.dump_bitset = vm_page_dump;
        }
 
        error = cpu_minidumpsys(di, &state);
        if (livedump) {
                free(msg_ptr, M_TEMP);
                free(state.dump_bitset, M_TEMP);
        }
 
        return (error);
}
#endif /* MINIDUMP_PAGE_TRACKING == 1 */