freebsd-dev/lib/libkvm/kvm_private.c
2017-11-12 01:36:48 +00:00

768 lines
20 KiB
C

/*-
* Copyright (c) 1989, 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software developed by the Computer Systems
* Engineering group at Lawrence Berkeley Laboratory under DARPA contract
* BG 91-66 and contributed to Berkeley.
*
* 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.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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/fnv_hash.h>
#define _WANT_VNET
#include <sys/user.h>
#include <sys/linker.h>
#include <sys/pcpu.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <net/vnet.h>
#include <assert.h>
#include <fcntl.h>
#include <vm/vm.h>
#include <kvm.h>
#include <limits.h>
#include <paths.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdarg.h>
#include <inttypes.h>
#include "kvm_private.h"
/*
* Routines private to libkvm.
*/
/* from src/lib/libc/gen/nlist.c */
int __fdnlist(int, struct nlist *);
/*
* Report an error using printf style arguments. "program" is kd->program
* on hard errors, and 0 on soft errors, so that under sun error emulation,
* only hard errors are printed out (otherwise, programs like gdb will
* generate tons of error messages when trying to access bogus pointers).
*/
void
_kvm_err(kvm_t *kd, const char *program, const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
if (program != NULL) {
(void)fprintf(stderr, "%s: ", program);
(void)vfprintf(stderr, fmt, ap);
(void)fputc('\n', stderr);
} else
(void)vsnprintf(kd->errbuf,
sizeof(kd->errbuf), fmt, ap);
va_end(ap);
}
void
_kvm_syserr(kvm_t *kd, const char *program, const char *fmt, ...)
{
va_list ap;
int n;
va_start(ap, fmt);
if (program != NULL) {
(void)fprintf(stderr, "%s: ", program);
(void)vfprintf(stderr, fmt, ap);
(void)fprintf(stderr, ": %s\n", strerror(errno));
} else {
char *cp = kd->errbuf;
(void)vsnprintf(cp, sizeof(kd->errbuf), fmt, ap);
n = strlen(cp);
(void)snprintf(&cp[n], sizeof(kd->errbuf) - n, ": %s",
strerror(errno));
}
va_end(ap);
}
void *
_kvm_malloc(kvm_t *kd, size_t n)
{
void *p;
if ((p = calloc(n, sizeof(char))) == NULL)
_kvm_err(kd, kd->program, "can't allocate %zu bytes: %s",
n, strerror(errno));
return (p);
}
int
_kvm_probe_elf_kernel(kvm_t *kd, int class, int machine)
{
return (kd->nlehdr.e_ident[EI_CLASS] == class &&
kd->nlehdr.e_type == ET_EXEC &&
kd->nlehdr.e_machine == machine);
}
int
_kvm_is_minidump(kvm_t *kd)
{
char minihdr[8];
if (kd->rawdump)
return (0);
if (pread(kd->pmfd, &minihdr, 8, 0) == 8 &&
memcmp(&minihdr, "minidump", 8) == 0)
return (1);
return (0);
}
/*
* The powerpc backend has a hack to strip a leading kerneldump
* header from the core before treating it as an ELF header.
*
* We can add that here if we can get a change to libelf to support
* an initial offset into the file. Alternatively we could patch
* savecore to extract cores from a regular file instead.
*/
int
_kvm_read_core_phdrs(kvm_t *kd, size_t *phnump, GElf_Phdr **phdrp)
{
GElf_Ehdr ehdr;
GElf_Phdr *phdr;
Elf *elf;
size_t i, phnum;
elf = elf_begin(kd->pmfd, ELF_C_READ, NULL);
if (elf == NULL) {
_kvm_err(kd, kd->program, "%s", elf_errmsg(0));
return (-1);
}
if (elf_kind(elf) != ELF_K_ELF) {
_kvm_err(kd, kd->program, "invalid core");
goto bad;
}
if (gelf_getclass(elf) != kd->nlehdr.e_ident[EI_CLASS]) {
_kvm_err(kd, kd->program, "invalid core");
goto bad;
}
if (gelf_getehdr(elf, &ehdr) == NULL) {
_kvm_err(kd, kd->program, "%s", elf_errmsg(0));
goto bad;
}
if (ehdr.e_type != ET_CORE) {
_kvm_err(kd, kd->program, "invalid core");
goto bad;
}
if (ehdr.e_machine != kd->nlehdr.e_machine) {
_kvm_err(kd, kd->program, "invalid core");
goto bad;
}
if (elf_getphdrnum(elf, &phnum) == -1) {
_kvm_err(kd, kd->program, "%s", elf_errmsg(0));
goto bad;
}
phdr = calloc(phnum, sizeof(*phdr));
if (phdr == NULL) {
_kvm_err(kd, kd->program, "failed to allocate phdrs");
goto bad;
}
for (i = 0; i < phnum; i++) {
if (gelf_getphdr(elf, i, &phdr[i]) == NULL) {
free(phdr);
_kvm_err(kd, kd->program, "%s", elf_errmsg(0));
goto bad;
}
}
elf_end(elf);
*phnump = phnum;
*phdrp = phdr;
return (0);
bad:
elf_end(elf);
return (-1);
}
/*
* Transform v such that only bits [bit0, bitN) may be set. Generates a
* bitmask covering the number of bits, then shifts so +bit0+ is the first.
*/
static uint64_t
bitmask_range(uint64_t v, uint64_t bit0, uint64_t bitN)
{
if (bit0 == 0 && bitN == BITS_IN(v))
return (v);
return (v & (((1ULL << (bitN - bit0)) - 1ULL) << bit0));
}
/*
* Returns the number of bits in a given byte array range starting at a
* given base, from bit0 to bitN. bit0 may be non-zero in the case of
* counting backwards from bitN.
*/
static uint64_t
popcount_bytes(uint64_t *addr, uint32_t bit0, uint32_t bitN)
{
uint32_t res = bitN - bit0;
uint64_t count = 0;
uint32_t bound;
/* Align to 64-bit boundary on the left side if needed. */
if ((bit0 % BITS_IN(*addr)) != 0) {
bound = MIN(bitN, roundup2(bit0, BITS_IN(*addr)));
count += __bitcount64(bitmask_range(*addr, bit0, bound));
res -= (bound - bit0);
addr++;
}
while (res > 0) {
bound = MIN(res, BITS_IN(*addr));
count += __bitcount64(bitmask_range(*addr, 0, bound));
res -= bound;
addr++;
}
return (count);
}
void *
_kvm_pmap_get(kvm_t *kd, u_long idx, size_t len)
{
uintptr_t off = idx * len;
if ((off_t)off >= kd->pt_sparse_off)
return (NULL);
return (void *)((uintptr_t)kd->page_map + off);
}
void *
_kvm_map_get(kvm_t *kd, u_long pa, unsigned int page_size)
{
off_t off;
uintptr_t addr;
off = _kvm_pt_find(kd, pa, page_size);
if (off == -1)
return NULL;
addr = (uintptr_t)kd->page_map + off;
if (off >= kd->pt_sparse_off)
addr = (uintptr_t)kd->sparse_map + (off - kd->pt_sparse_off);
return (void *)addr;
}
int
_kvm_pt_init(kvm_t *kd, size_t map_len, off_t map_off, off_t sparse_off,
int page_size, int word_size)
{
uint64_t *addr;
uint32_t *popcount_bin;
int bin_popcounts = 0;
uint64_t pc_bins, res;
ssize_t rd;
/*
* Map the bitmap specified by the arguments.
*/
kd->pt_map = _kvm_malloc(kd, map_len);
if (kd->pt_map == NULL) {
_kvm_err(kd, kd->program, "cannot allocate %zu bytes for bitmap",
map_len);
return (-1);
}
rd = pread(kd->pmfd, kd->pt_map, map_len, map_off);
if (rd < 0 || rd != (ssize_t)map_len) {
_kvm_err(kd, kd->program, "cannot read %zu bytes for bitmap",
map_len);
return (-1);
}
kd->pt_map_size = map_len;
/*
* Generate a popcount cache for every POPCOUNT_BITS in the bitmap,
* so lookups only have to calculate the number of bits set between
* a cache point and their bit. This reduces lookups to O(1),
* without significantly increasing memory requirements.
*
* Round up the number of bins so that 'upper half' lookups work for
* the final bin, if needed. The first popcount is 0, since no bits
* precede bit 0, so add 1 for that also. Without this, extra work
* would be needed to handle the first PTEs in _kvm_pt_find().
*/
addr = kd->pt_map;
res = map_len;
pc_bins = 1 + (res * NBBY + POPCOUNT_BITS / 2) / POPCOUNT_BITS;
kd->pt_popcounts = calloc(pc_bins, sizeof(uint32_t));
if (kd->pt_popcounts == NULL) {
_kvm_err(kd, kd->program, "cannot allocate popcount bins");
return (-1);
}
for (popcount_bin = &kd->pt_popcounts[1]; res > 0;
addr++, res -= sizeof(*addr)) {
*popcount_bin += popcount_bytes(addr, 0,
MIN(res * NBBY, BITS_IN(*addr)));
if (++bin_popcounts == POPCOUNTS_IN(*addr)) {
popcount_bin++;
*popcount_bin = *(popcount_bin - 1);
bin_popcounts = 0;
}
}
assert(pc_bins * sizeof(*popcount_bin) ==
((uintptr_t)popcount_bin - (uintptr_t)kd->pt_popcounts));
kd->pt_sparse_off = sparse_off;
kd->pt_sparse_size = (uint64_t)*popcount_bin * page_size;
kd->pt_page_size = page_size;
kd->pt_word_size = word_size;
/*
* Map the sparse page array. This is useful for performing point
* lookups of specific pages, e.g. for kvm_walk_pages. Generally,
* this is much larger than is reasonable to read in up front, so
* mmap it in instead.
*/
kd->sparse_map = mmap(NULL, kd->pt_sparse_size, PROT_READ,
MAP_PRIVATE, kd->pmfd, kd->pt_sparse_off);
if (kd->sparse_map == MAP_FAILED) {
_kvm_err(kd, kd->program, "cannot map %" PRIu64
" bytes from fd %d offset %jd for sparse map: %s",
kd->pt_sparse_size, kd->pmfd,
(intmax_t)kd->pt_sparse_off, strerror(errno));
return (-1);
}
return (0);
}
int
_kvm_pmap_init(kvm_t *kd, uint32_t pmap_size, off_t pmap_off)
{
ssize_t exp_len = pmap_size;
kd->page_map_size = pmap_size;
kd->page_map_off = pmap_off;
kd->page_map = _kvm_malloc(kd, pmap_size);
if (kd->page_map == NULL) {
_kvm_err(kd, kd->program, "cannot allocate %u bytes "
"for page map", pmap_size);
return (-1);
}
if (pread(kd->pmfd, kd->page_map, pmap_size, pmap_off) != exp_len) {
_kvm_err(kd, kd->program, "cannot read %d bytes from "
"offset %jd for page map", pmap_size, (intmax_t)pmap_off);
return (-1);
}
return (0);
}
/*
* Find the offset for the given physical page address; returns -1 otherwise.
*
* A page's offset is represented by the sparse page base offset plus the
* number of bits set before its bit multiplied by page size. This means
* that if a page exists in the dump, it's necessary to know how many pages
* in the dump precede it. Reduce this O(n) counting to O(1) by caching the
* number of bits set at POPCOUNT_BITS intervals.
*
* Then to find the number of pages before the requested address, simply
* index into the cache and count the number of bits set between that cache
* bin and the page's bit. Halve the number of bytes that have to be
* checked by also counting down from the next higher bin if it's closer.
*/
off_t
_kvm_pt_find(kvm_t *kd, uint64_t pa, unsigned int page_size)
{
uint64_t *bitmap = kd->pt_map;
uint64_t pte_bit_id = pa / page_size;
uint64_t pte_u64 = pte_bit_id / BITS_IN(*bitmap);
uint64_t popcount_id = pte_bit_id / POPCOUNT_BITS;
uint64_t pte_mask = 1ULL << (pte_bit_id % BITS_IN(*bitmap));
uint64_t bitN;
uint32_t count;
/* Check whether the page address requested is in the dump. */
if (pte_bit_id >= (kd->pt_map_size * NBBY) ||
(bitmap[pte_u64] & pte_mask) == 0)
return (-1);
/*
* Add/sub popcounts from the bitmap until the PTE's bit is reached.
* For bits that are in the upper half between the calculated
* popcount id and the next one, use the next one and subtract to
* minimize the number of popcounts required.
*/
if ((pte_bit_id % POPCOUNT_BITS) < (POPCOUNT_BITS / 2)) {
count = kd->pt_popcounts[popcount_id] + popcount_bytes(
bitmap + popcount_id * POPCOUNTS_IN(*bitmap),
0, pte_bit_id - popcount_id * POPCOUNT_BITS);
} else {
/*
* Counting in reverse is trickier, since we must avoid
* reading from bytes that are not in range, and invert.
*/
uint64_t pte_u64_bit_off = pte_u64 * BITS_IN(*bitmap);
popcount_id++;
bitN = MIN(popcount_id * POPCOUNT_BITS,
kd->pt_map_size * BITS_IN(uint8_t));
count = kd->pt_popcounts[popcount_id] - popcount_bytes(
bitmap + pte_u64,
pte_bit_id - pte_u64_bit_off, bitN - pte_u64_bit_off);
}
/*
* This can only happen if the core is truncated. Treat these
* entries as if they don't exist, since their backing doesn't.
*/
if (count >= (kd->pt_sparse_size / page_size))
return (-1);
return (kd->pt_sparse_off + (uint64_t)count * page_size);
}
static int
kvm_fdnlist(kvm_t *kd, struct kvm_nlist *list)
{
kvaddr_t addr;
int error, nfail;
if (kd->resolve_symbol == NULL) {
struct nlist *nl;
int count, i;
for (count = 0; list[count].n_name != NULL &&
list[count].n_name[0] != '\0'; count++)
;
nl = calloc(count + 1, sizeof(*nl));
for (i = 0; i < count; i++)
nl[i].n_name = list[i].n_name;
nfail = __fdnlist(kd->nlfd, nl);
for (i = 0; i < count; i++) {
list[i].n_type = nl[i].n_type;
list[i].n_value = nl[i].n_value;
}
free(nl);
return (nfail);
}
nfail = 0;
while (list->n_name != NULL && list->n_name[0] != '\0') {
error = kd->resolve_symbol(list->n_name, &addr);
if (error != 0) {
nfail++;
list->n_value = 0;
list->n_type = 0;
} else {
list->n_value = addr;
list->n_type = N_DATA | N_EXT;
}
list++;
}
return (nfail);
}
/*
* Walk the list of unresolved symbols, generate a new list and prefix the
* symbol names, try again, and merge back what we could resolve.
*/
static int
kvm_fdnlist_prefix(kvm_t *kd, struct kvm_nlist *nl, int missing,
const char *prefix, kvaddr_t (*validate_fn)(kvm_t *, kvaddr_t))
{
struct kvm_nlist *n, *np, *p;
char *cp, *ce;
const char *ccp;
size_t len;
int slen, unresolved;
/*
* Calculate the space we need to malloc for nlist and names.
* We are going to store the name twice for later lookups: once
* with the prefix and once the unmodified name delmited by \0.
*/
len = 0;
unresolved = 0;
for (p = nl; p->n_name && p->n_name[0]; ++p) {
if (p->n_type != N_UNDF)
continue;
len += sizeof(struct kvm_nlist) + strlen(prefix) +
2 * (strlen(p->n_name) + 1);
unresolved++;
}
if (unresolved == 0)
return (unresolved);
/* Add space for the terminating nlist entry. */
len += sizeof(struct kvm_nlist);
unresolved++;
/* Alloc one chunk for (nlist, [names]) and setup pointers. */
n = np = malloc(len);
bzero(n, len);
if (n == NULL)
return (missing);
cp = ce = (char *)np;
cp += unresolved * sizeof(struct kvm_nlist);
ce += len;
/* Generate shortened nlist with special prefix. */
unresolved = 0;
for (p = nl; p->n_name && p->n_name[0]; ++p) {
if (p->n_type != N_UNDF)
continue;
*np = *p;
/* Save the new\0orig. name so we can later match it again. */
slen = snprintf(cp, ce - cp, "%s%s%c%s", prefix,
(prefix[0] != '\0' && p->n_name[0] == '_') ?
(p->n_name + 1) : p->n_name, '\0', p->n_name);
if (slen < 0 || slen >= ce - cp)
continue;
np->n_name = cp;
cp += slen + 1;
np++;
unresolved++;
}
/* Do lookup on the reduced list. */
np = n;
unresolved = kvm_fdnlist(kd, np);
/* Check if we could resolve further symbols and update the list. */
if (unresolved >= 0 && unresolved < missing) {
/* Find the first freshly resolved entry. */
for (; np->n_name && np->n_name[0]; np++)
if (np->n_type != N_UNDF)
break;
/*
* The lists are both in the same order,
* so we can walk them in parallel.
*/
for (p = nl; np->n_name && np->n_name[0] &&
p->n_name && p->n_name[0]; ++p) {
if (p->n_type != N_UNDF)
continue;
/* Skip expanded name and compare to orig. one. */
ccp = np->n_name + strlen(np->n_name) + 1;
if (strcmp(ccp, p->n_name) != 0)
continue;
/* Update nlist with new, translated results. */
p->n_type = np->n_type;
if (validate_fn)
p->n_value = (*validate_fn)(kd, np->n_value);
else
p->n_value = np->n_value;
missing--;
/* Find next freshly resolved entry. */
for (np++; np->n_name && np->n_name[0]; np++)
if (np->n_type != N_UNDF)
break;
}
}
/* We could assert missing = unresolved here. */
free(n);
return (unresolved);
}
int
_kvm_nlist(kvm_t *kd, struct kvm_nlist *nl, int initialize)
{
struct kvm_nlist *p;
int nvalid;
struct kld_sym_lookup lookup;
int error;
const char *prefix = "";
char symname[1024]; /* XXX-BZ symbol name length limit? */
int tried_vnet, tried_dpcpu;
/*
* If we can't use the kld symbol lookup, revert to the
* slow library call.
*/
if (!ISALIVE(kd)) {
error = kvm_fdnlist(kd, nl);
if (error <= 0) /* Hard error or success. */
return (error);
if (_kvm_vnet_initialized(kd, initialize))
error = kvm_fdnlist_prefix(kd, nl, error,
VNET_SYMPREFIX, _kvm_vnet_validaddr);
if (error > 0 && _kvm_dpcpu_initialized(kd, initialize))
error = kvm_fdnlist_prefix(kd, nl, error,
DPCPU_SYMPREFIX, _kvm_dpcpu_validaddr);
return (error);
}
/*
* We can use the kld lookup syscall. Go through each nlist entry
* and look it up with a kldsym(2) syscall.
*/
nvalid = 0;
tried_vnet = 0;
tried_dpcpu = 0;
again:
for (p = nl; p->n_name && p->n_name[0]; ++p) {
if (p->n_type != N_UNDF)
continue;
lookup.version = sizeof(lookup);
lookup.symvalue = 0;
lookup.symsize = 0;
error = snprintf(symname, sizeof(symname), "%s%s", prefix,
(prefix[0] != '\0' && p->n_name[0] == '_') ?
(p->n_name + 1) : p->n_name);
if (error < 0 || error >= (int)sizeof(symname))
continue;
lookup.symname = symname;
if (lookup.symname[0] == '_')
lookup.symname++;
if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) {
p->n_type = N_TEXT;
if (_kvm_vnet_initialized(kd, initialize) &&
strcmp(prefix, VNET_SYMPREFIX) == 0)
p->n_value =
_kvm_vnet_validaddr(kd, lookup.symvalue);
else if (_kvm_dpcpu_initialized(kd, initialize) &&
strcmp(prefix, DPCPU_SYMPREFIX) == 0)
p->n_value =
_kvm_dpcpu_validaddr(kd, lookup.symvalue);
else
p->n_value = lookup.symvalue;
++nvalid;
/* lookup.symsize */
}
}
/*
* Check the number of entries that weren't found. If they exist,
* try again with a prefix for virtualized or DPCPU symbol names.
*/
error = ((p - nl) - nvalid);
if (error && _kvm_vnet_initialized(kd, initialize) && !tried_vnet) {
tried_vnet = 1;
prefix = VNET_SYMPREFIX;
goto again;
}
if (error && _kvm_dpcpu_initialized(kd, initialize) && !tried_dpcpu) {
tried_dpcpu = 1;
prefix = DPCPU_SYMPREFIX;
goto again;
}
/*
* Return the number of entries that weren't found. If they exist,
* also fill internal error buffer.
*/
error = ((p - nl) - nvalid);
if (error)
_kvm_syserr(kd, kd->program, "kvm_nlist");
return (error);
}
int
_kvm_bitmap_init(struct kvm_bitmap *bm, u_long bitmapsize, u_long *idx)
{
*idx = ULONG_MAX;
bm->map = calloc(bitmapsize, sizeof *bm->map);
if (bm->map == NULL)
return (0);
bm->size = bitmapsize;
return (1);
}
void
_kvm_bitmap_set(struct kvm_bitmap *bm, u_long pa, unsigned int page_size)
{
u_long bm_index = pa / page_size;
uint8_t *byte = &bm->map[bm_index / 8];
*byte |= (1UL << (bm_index % 8));
}
int
_kvm_bitmap_next(struct kvm_bitmap *bm, u_long *idx)
{
u_long first_invalid = bm->size * CHAR_BIT;
if (*idx == ULONG_MAX)
*idx = 0;
else
(*idx)++;
/* Find the next valid idx. */
for (; *idx < first_invalid; (*idx)++) {
unsigned int mask = *idx % CHAR_BIT;
if ((bm->map[*idx * CHAR_BIT] & mask) == 0)
break;
}
return (*idx < first_invalid);
}
void
_kvm_bitmap_deinit(struct kvm_bitmap *bm)
{
free(bm->map);
}
int
_kvm_visit_cb(kvm_t *kd, kvm_walk_pages_cb_t *cb, void *arg, u_long pa,
u_long kmap_vaddr, u_long dmap_vaddr, vm_prot_t prot, size_t len,
unsigned int page_size)
{
unsigned int pgsz = page_size ? page_size : len;
struct kvm_page p = {
.version = LIBKVM_WALK_PAGES_VERSION,
.paddr = pa,
.kmap_vaddr = kmap_vaddr,
.dmap_vaddr = dmap_vaddr,
.prot = prot,
.offset = _kvm_pt_find(kd, pa, pgsz),
.len = len,
};
return cb(&p, arg);
}