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NetBSD/sys/kern/kern_ksyms.c

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/* $NetBSD: kern_ksyms.c,v 1.88 2020/01/05 21:12:34 pgoyette Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software developed for The NetBSD Foundation
* by Andrew Doran.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* Copyright (c) 2001, 2003 Anders Magnusson (ragge@ludd.luth.se).
* 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.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission
*
* 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.
*/
/*
* Code to deal with in-kernel symbol table management + /dev/ksyms.
*
* For each loaded module the symbol table info is kept track of by a
* struct, placed in a circular list. The first entry is the kernel
* symbol table.
*/
/*
* TODO:
*
* Add support for mmap, poll.
* Constify tables.
* Constify db_symtab and move it to .rodata.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_ksyms.c,v 1.88 2020/01/05 21:12:34 pgoyette Exp $");
#if defined(_KERNEL) && defined(_KERNEL_OPT)
#include "opt_copy_symtab.h"
#include "opt_ddb.h"
#include "opt_dtrace.h"
#endif
#define _KSYMS_PRIVATE
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/exec.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/kmem.h>
#include <sys/proc.h>
#include <sys/atomic.h>
#include <sys/ksyms.h>
#ifdef DDB
#include <ddb/db_output.h>
#endif
#include "ksyms.h"
#if NKSYMS > 0
#include "ioconf.h"
#endif
#define KSYMS_MAX_ID 98304
#ifdef KDTRACE_HOOKS
static uint32_t ksyms_nmap[KSYMS_MAX_ID]; /* sorted symbol table map */
#else
static uint32_t *ksyms_nmap = NULL;
#endif
static int ksyms_maxlen;
static bool ksyms_isopen;
static bool ksyms_initted;
static bool ksyms_loaded;
static kmutex_t ksyms_lock __cacheline_aligned;
static struct ksyms_symtab kernel_symtab;
static void ksyms_hdr_init(const void *);
static void ksyms_sizes_calc(void);
#ifdef KSYMS_DEBUG
#define FOLLOW_CALLS 1
#define FOLLOW_MORE_CALLS 2
#define FOLLOW_DEVKSYMS 4
static int ksyms_debug;
#endif
#define SYMTAB_FILLER "|This is the symbol table!"
#ifdef makeoptions_COPY_SYMTAB
extern char db_symtab[];
extern int db_symtabsize;
#endif
/*
* used by savecore(8) so non-static
*/
struct ksyms_hdr ksyms_hdr;
int ksyms_symsz;
int ksyms_strsz;
int ksyms_ctfsz; /* this is not currently used by savecore(8) */
TAILQ_HEAD(, ksyms_symtab) ksyms_symtabs =
TAILQ_HEAD_INITIALIZER(ksyms_symtabs);
static int
ksyms_verify(const void *symstart, const void *strstart)
{
#if defined(DIAGNOSTIC) || defined(DEBUG)
if (symstart == NULL)
printf("ksyms: Symbol table not found\n");
if (strstart == NULL)
printf("ksyms: String table not found\n");
if (symstart == NULL || strstart == NULL)
printf("ksyms: Perhaps the kernel is stripped?\n");
#endif
if (symstart == NULL || strstart == NULL)
return 0;
return 1;
}
/*
* Finds a certain symbol name in a certain symbol table.
*/
static Elf_Sym *
findsym(const char *name, struct ksyms_symtab *table, int type)
{
Elf_Sym *sym, *maxsym;
int low, mid, high, nglob;
char *str, *cmp;
sym = table->sd_symstart;
str = table->sd_strstart - table->sd_usroffset;
nglob = table->sd_nglob;
low = 0;
high = nglob;
/*
* Start with a binary search of all global symbols in this table.
* Global symbols must have unique names.
*/
while (low < high) {
mid = (low + high) >> 1;
cmp = sym[mid].st_name + str;
if (cmp[0] < name[0] || strcmp(cmp, name) < 0) {
low = mid + 1;
} else {
high = mid;
}
}
KASSERT(low == high);
if (__predict_true(low < nglob &&
strcmp(sym[low].st_name + str, name) == 0)) {
KASSERT(ELF_ST_BIND(sym[low].st_info) == STB_GLOBAL);
return &sym[low];
}
/*
* Perform a linear search of local symbols (rare). Many local
* symbols with the same name can exist so are not included in
* the binary search.
*/
if (type != KSYMS_EXTERN) {
maxsym = sym + table->sd_symsize / sizeof(Elf_Sym);
for (sym += nglob; sym < maxsym; sym++) {
if (strcmp(name, sym->st_name + str) == 0) {
return sym;
}
}
}
return NULL;
}
/*
* The "attach" is in reality done in ksyms_init().
*/
#if NKSYMS > 0
/*
* ksyms can be loaded even if the kernel has a missing "pseudo-device ksyms"
* statement because ddb and modules require it. Fixing it properly requires
* fixing config to warn about required, but missing preudo-devices. For now,
* if we don't have the pseudo-device we don't need the attach function; this
* is fine, as it does nothing.
*/
void
ksymsattach(int arg)
{
}
#endif
void
ksyms_init(void)
{
#ifdef makeoptions_COPY_SYMTAB
if (!ksyms_loaded &&
strncmp(db_symtab, SYMTAB_FILLER, sizeof(SYMTAB_FILLER))) {
ksyms_addsyms_elf(db_symtabsize, db_symtab,
db_symtab + db_symtabsize);
}
#endif
if (!ksyms_initted) {
mutex_init(&ksyms_lock, MUTEX_DEFAULT, IPL_NONE);
ksyms_initted = true;
}
}
/*
* Add a symbol table.
* This is intended for use when the symbol table and its corresponding
* string table are easily available. If they are embedded in an ELF
* image, use addsymtab_elf() instead.
*
* name - Symbol's table name.
* symstart, symsize - Address and size of the symbol table.
* strstart, strsize - Address and size of the string table.
* tab - Symbol table to be updated with this information.
* newstart - Address to which the symbol table has to be copied during
* shrinking. If NULL, it is not moved.
*/
static const char *addsymtab_strstart;
static int
addsymtab_compar(const void *a, const void *b)
{
const Elf_Sym *sa, *sb;
sa = a;
sb = b;
/*
* Split the symbol table into two, with globals at the start
* and locals at the end.
*/
if (ELF_ST_BIND(sa->st_info) != ELF_ST_BIND(sb->st_info)) {
if (ELF_ST_BIND(sa->st_info) == STB_GLOBAL) {
return -1;
}
if (ELF_ST_BIND(sb->st_info) == STB_GLOBAL) {
return 1;
}
}
/* Within each band, sort by name. */
return strcmp(sa->st_name + addsymtab_strstart,
sb->st_name + addsymtab_strstart);
}
static void
addsymtab(const char *name, void *symstart, size_t symsize,
void *strstart, size_t strsize, struct ksyms_symtab *tab,
void *newstart, void *ctfstart, size_t ctfsize, uint32_t *nmap)
{
Elf_Sym *sym, *nsym, ts;
int i, j, n, nglob;
char *str;
int nsyms = symsize / sizeof(Elf_Sym);
/* Sanity check for pre-allocated map table used during startup. */
if ((nmap == ksyms_nmap) && (nsyms >= KSYMS_MAX_ID)) {
printf("kern_ksyms: ERROR %d > %d, increase KSYMS_MAX_ID\n",
nsyms, KSYMS_MAX_ID);
/* truncate for now */
nsyms = KSYMS_MAX_ID - 1;
}
tab->sd_symstart = symstart;
tab->sd_symsize = symsize;
tab->sd_strstart = strstart;
tab->sd_strsize = strsize;
tab->sd_name = name;
tab->sd_minsym = UINTPTR_MAX;
tab->sd_maxsym = 0;
tab->sd_usroffset = 0;
tab->sd_gone = false;
tab->sd_ctfstart = ctfstart;
tab->sd_ctfsize = ctfsize;
tab->sd_nmap = nmap;
tab->sd_nmapsize = nsyms;
#ifdef KSYMS_DEBUG
printf("newstart %p sym %p ksyms_symsz %zu str %p strsz %zu send %p\n",
newstart, symstart, symsize, strstart, strsize,
tab->sd_strstart + tab->sd_strsize);
#endif
if (nmap) {
memset(nmap, 0, nsyms * sizeof(uint32_t));
}
/* Pack symbol table by removing all file name references. */
sym = tab->sd_symstart;
nsym = (Elf_Sym *)newstart;
str = tab->sd_strstart;
nglob = 0;
for (i = n = 0; i < nsyms; i++) {
/*
* This breaks CTF mapping, so don't do it when
* DTrace is enabled.
*/
#ifndef KDTRACE_HOOKS
/*
* Remove useless symbols.
* Should actually remove all typeless symbols.
*/
if (sym[i].st_name == 0)
continue; /* Skip nameless entries */
if (sym[i].st_shndx == SHN_UNDEF)
continue; /* Skip external references */
if (ELF_ST_TYPE(sym[i].st_info) == STT_FILE)
continue; /* Skip filenames */
if (ELF_ST_TYPE(sym[i].st_info) == STT_NOTYPE &&
sym[i].st_value == 0 &&
strcmp(str + sym[i].st_name, "*ABS*") == 0)
continue; /* XXX */
if (ELF_ST_TYPE(sym[i].st_info) == STT_NOTYPE &&
strcmp(str + sym[i].st_name, "gcc2_compiled.") == 0)
continue; /* XXX */
#endif
/* Save symbol. Set it as an absolute offset */
nsym[n] = sym[i];
#ifdef KDTRACE_HOOKS
if (nmap != NULL) {
/*
* Save the size, replace it with the symbol id so
* the mapping can be done after the cleanup and sort.
*/
nmap[i] = nsym[n].st_size;
nsym[n].st_size = i + 1; /* zero is reserved */
}
#endif
if (sym[i].st_shndx != SHN_ABS) {
nsym[n].st_shndx = SHBSS;
} else {
/* SHN_ABS is a magic value, don't overwrite it */
}
j = strlen(nsym[n].st_name + str) + 1;
if (j > ksyms_maxlen)
ksyms_maxlen = j;
nglob += (ELF_ST_BIND(nsym[n].st_info) == STB_GLOBAL);
/* Compute min and max symbols. */
if (strcmp(str + sym[i].st_name, "*ABS*") != 0
&& ELF_ST_TYPE(nsym[n].st_info) != STT_NOTYPE) {
if (nsym[n].st_value < tab->sd_minsym) {
tab->sd_minsym = nsym[n].st_value;
}
if (nsym[n].st_value > tab->sd_maxsym) {
tab->sd_maxsym = nsym[n].st_value;
}
}
n++;
}
/* Fill the rest of the record, and sort the symbols. */
tab->sd_symstart = nsym;
tab->sd_symsize = n * sizeof(Elf_Sym);
tab->sd_nglob = nglob;
addsymtab_strstart = str;
if (kheapsort(nsym, n, sizeof(Elf_Sym), addsymtab_compar, &ts) != 0)
panic("addsymtab");
#ifdef KDTRACE_HOOKS
/*
* Build the mapping from original symbol id to new symbol table.
* Deleted symbols will have a zero map, indices will be one based
* instead of zero based.
* Resulting map is sd_nmap[original_index] = new_index + 1
*/
if (nmap != NULL) {
int new;
for (new = 0; new < n; new++) {
uint32_t orig = nsym[new].st_size - 1;
uint32_t size = nmap[orig];
nmap[orig] = new + 1;
/* restore the size */
nsym[new].st_size = size;
}
}
#endif
/* ksymsread() is unlocked, so membar. */
membar_producer();
TAILQ_INSERT_TAIL(&ksyms_symtabs, tab, sd_queue);
ksyms_sizes_calc();
ksyms_loaded = true;
}
/*
* Setup the kernel symbol table stuff.
*/
void
ksyms_addsyms_elf(int symsize, void *start, void *end)
{
int i, j;
Elf_Shdr *shdr;
char *symstart = NULL, *strstart = NULL;
size_t strsize = 0;
Elf_Ehdr *ehdr;
char *ctfstart = NULL;
size_t ctfsize = 0;
if (symsize <= 0) {
printf("[ Kernel symbol table missing! ]\n");
return;
}
/* Sanity check */
if (ALIGNED_POINTER(start, long) == 0) {
printf("[ Kernel symbol table has bad start address %p ]\n",
start);
return;
}
ehdr = (Elf_Ehdr *)start;
/* check if this is a valid ELF header */
/* No reason to verify arch type, the kernel is actually running! */
if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) ||
ehdr->e_ident[EI_CLASS] != ELFCLASS ||
ehdr->e_version > 1) {
printf("[ Kernel symbol table invalid! ]\n");
return; /* nothing to do */
}
/* Loaded header will be scratched in addsymtab */
ksyms_hdr_init(start);
/* Find the symbol table and the corresponding string table. */
shdr = (Elf_Shdr *)((uint8_t *)start + ehdr->e_shoff);
for (i = 1; i < ehdr->e_shnum; i++) {
if (shdr[i].sh_type != SHT_SYMTAB)
continue;
if (shdr[i].sh_offset == 0)
continue;
symstart = (uint8_t *)start + shdr[i].sh_offset;
symsize = shdr[i].sh_size;
j = shdr[i].sh_link;
if (shdr[j].sh_offset == 0)
continue; /* Can this happen? */
strstart = (uint8_t *)start + shdr[j].sh_offset;
strsize = shdr[j].sh_size;
break;
}
#ifdef KDTRACE_HOOKS
/* Find the CTF section */
shdr = (Elf_Shdr *)((uint8_t *)start + ehdr->e_shoff);
if (ehdr->e_shstrndx != 0) {
char *shstr = (uint8_t *)start +
shdr[ehdr->e_shstrndx].sh_offset;
for (i = 1; i < ehdr->e_shnum; i++) {
#ifdef DEBUG
printf("ksyms: checking %s\n", &shstr[shdr[i].sh_name]);
#endif
if (shdr[i].sh_type != SHT_PROGBITS)
continue;
if (strncmp(".SUNW_ctf", &shstr[shdr[i].sh_name], 10)
!= 0)
continue;
ctfstart = (uint8_t *)start + shdr[i].sh_offset;
ctfsize = shdr[i].sh_size;
ksyms_ctfsz = ctfsize;
#ifdef DEBUG
aprint_normal("Found CTF at %p, size 0x%zx\n",
ctfstart, ctfsize);
#endif
break;
}
#ifdef DEBUG
} else {
printf("ksyms: e_shstrndx == 0\n");
#endif
}
#endif
if (!ksyms_verify(symstart, strstart))
return;
addsymtab("netbsd", symstart, symsize, strstart, strsize,
&kernel_symtab, symstart, ctfstart, ctfsize, ksyms_nmap);
#ifdef DEBUG
aprint_normal("Loaded initial symtab at %p, strtab at %p, # entries %ld\n",
kernel_symtab.sd_symstart, kernel_symtab.sd_strstart,
(long)kernel_symtab.sd_symsize/sizeof(Elf_Sym));
#endif
}
/*
* Setup the kernel symbol table stuff.
* Use this when the address of the symbol and string tables are known;
* otherwise use ksyms_init with an ELF image.
* We need to pass a minimal ELF header which will later be completed by
* ksyms_hdr_init and handed off to userland through /dev/ksyms. We use
* a void *rather than a pointer to avoid exposing the Elf_Ehdr type.
*/
void
ksyms_addsyms_explicit(void *ehdr, void *symstart, size_t symsize,
void *strstart, size_t strsize)
{
if (!ksyms_verify(symstart, strstart))
return;
ksyms_hdr_init(ehdr);
addsymtab("netbsd", symstart, symsize, strstart, strsize,
&kernel_symtab, symstart, NULL, 0, ksyms_nmap);
}
/*
* Get the value associated with a symbol.
* "mod" is the module name, or null if any module.
* "sym" is the symbol name.
* "val" is a pointer to the corresponding value, if call succeeded.
* Returns 0 if success or ENOENT if no such entry.
*
* Call with ksyms_lock, unless known that the symbol table can't change.
*/
int
ksyms_getval_unlocked(const char *mod, const char *sym, Elf_Sym **symp,
unsigned long *val, int type)
{
struct ksyms_symtab *st;
Elf_Sym *es;
#ifdef KSYMS_DEBUG
if (ksyms_debug & FOLLOW_CALLS)
printf("%s: mod %s sym %s valp %p\n", __func__, mod, sym, val);
#endif
TAILQ_FOREACH(st, &ksyms_symtabs, sd_queue) {
if (__predict_false(st->sd_gone))
continue;
if (mod != NULL && strcmp(st->sd_name, mod))
continue;
if ((es = findsym(sym, st, type)) != NULL) {
*val = es->st_value;
if (symp)
*symp = es;
return 0;
}
}
return ENOENT;
}
int
ksyms_getval(const char *mod, const char *sym, unsigned long *val, int type)
{
int rc;
if (!ksyms_loaded)
return ENOENT;
mutex_enter(&ksyms_lock);
rc = ksyms_getval_unlocked(mod, sym, NULL, val, type);
mutex_exit(&ksyms_lock);
return rc;
}
struct ksyms_symtab *
ksyms_get_mod(const char *mod)
{
struct ksyms_symtab *st;
mutex_enter(&ksyms_lock);
TAILQ_FOREACH(st, &ksyms_symtabs, sd_queue) {
if (__predict_false(st->sd_gone))
continue;
if (mod != NULL && strcmp(st->sd_name, mod))
continue;
break;
}
mutex_exit(&ksyms_lock);
return st;
}
/*
* ksyms_mod_foreach()
*
* Iterate over the symbol table of the specified module, calling the callback
* handler for each symbol. Stop iterating if the handler return is non-zero.
*
*/
int
ksyms_mod_foreach(const char *mod, ksyms_callback_t callback, void *opaque)
{
struct ksyms_symtab *st;
Elf_Sym *sym, *maxsym;
char *str;
int symindx;
if (!ksyms_loaded)
return ENOENT;
mutex_enter(&ksyms_lock);
/* find the module */
TAILQ_FOREACH(st, &ksyms_symtabs, sd_queue) {
if (__predict_false(st->sd_gone))
continue;
if (mod != NULL && strcmp(st->sd_name, mod))
continue;
sym = st->sd_symstart;
str = st->sd_strstart - st->sd_usroffset;
/* now iterate through the symbols */
maxsym = sym + st->sd_symsize / sizeof(Elf_Sym);
for (symindx = 0; sym < maxsym; sym++, symindx++) {
if (callback(str + sym->st_name, symindx,
(void *)sym->st_value,
sym->st_size,
sym->st_info,
opaque) != 0) {
break;
}
}
}
mutex_exit(&ksyms_lock);
return 0;
}
/*
* Get "mod" and "symbol" associated with an address.
* Returns 0 if success or ENOENT if no such entry.
*
* Call with ksyms_lock, unless known that the symbol table can't change.
*/
int
ksyms_getname(const char **mod, const char **sym, vaddr_t v, int f)
{
struct ksyms_symtab *st;
Elf_Sym *les, *es = NULL;
vaddr_t laddr = 0;
const char *lmod = NULL;
char *stable = NULL;
int type, i, sz;
if (!ksyms_loaded)
return ENOENT;
TAILQ_FOREACH(st, &ksyms_symtabs, sd_queue) {
if (st->sd_gone)
continue;
if (v < st->sd_minsym || v > st->sd_maxsym)
continue;
sz = st->sd_symsize/sizeof(Elf_Sym);
for (i = 0; i < sz; i++) {
les = st->sd_symstart + i;
type = ELF_ST_TYPE(les->st_info);
if ((f & KSYMS_PROC) && (type != STT_FUNC))
continue;
if (type == STT_NOTYPE)
continue;
if (((f & KSYMS_ANY) == 0) &&
(type != STT_FUNC) && (type != STT_OBJECT))
continue;
if ((les->st_value <= v) && (les->st_value > laddr)) {
laddr = les->st_value;
es = les;
lmod = st->sd_name;
stable = st->sd_strstart - st->sd_usroffset;
}
}
}
if (es == NULL)
return ENOENT;
if ((f & KSYMS_EXACT) && (v != es->st_value))
return ENOENT;
if (mod)
*mod = lmod;
if (sym)
*sym = stable + es->st_name;
return 0;
}
/*
* Add a symbol table from a loadable module.
*/
void
ksyms_modload(const char *name, void *symstart, vsize_t symsize,
char *strstart, vsize_t strsize)
{
struct ksyms_symtab *st;
void *nmap;
st = kmem_zalloc(sizeof(*st), KM_SLEEP);
nmap = kmem_zalloc(symsize / sizeof(Elf_Sym) * sizeof (uint32_t),
KM_SLEEP);
mutex_enter(&ksyms_lock);
addsymtab(name, symstart, symsize, strstart, strsize, st, symstart,
NULL, 0, nmap);
mutex_exit(&ksyms_lock);
}
/*
* Remove a symbol table from a loadable module.
*/
void
ksyms_modunload(const char *name)
{
struct ksyms_symtab *st;
mutex_enter(&ksyms_lock);
TAILQ_FOREACH(st, &ksyms_symtabs, sd_queue) {
if (st->sd_gone)
continue;
if (strcmp(name, st->sd_name) != 0)
continue;
st->sd_gone = true;
ksyms_sizes_calc();
if (!ksyms_isopen) {
TAILQ_REMOVE(&ksyms_symtabs, st, sd_queue);
kmem_free(st->sd_nmap,
st->sd_nmapsize * sizeof(uint32_t));
kmem_free(st, sizeof(*st));
}
break;
}
mutex_exit(&ksyms_lock);
KASSERT(st != NULL);
}
#ifdef DDB
/*
* Keep sifting stuff here, to avoid export of ksyms internals.
*
* Systems is expected to be quiescent, so no locking done.
*/
int
ksyms_sift(char *mod, char *sym, int mode)
{
struct ksyms_symtab *st;
char *sb;
int i, sz;
if (!ksyms_loaded)
return ENOENT;
TAILQ_FOREACH(st, &ksyms_symtabs, sd_queue) {
if (st->sd_gone)
continue;
if (mod && strcmp(mod, st->sd_name))
continue;
sb = st->sd_strstart - st->sd_usroffset;
sz = st->sd_symsize/sizeof(Elf_Sym);
for (i = 0; i < sz; i++) {
Elf_Sym *les = st->sd_symstart + i;
char c;
if (strstr(sb + les->st_name, sym) == NULL)
continue;
if (mode == 'F') {
switch (ELF_ST_TYPE(les->st_info)) {
case STT_OBJECT:
c = '+';
break;
case STT_FUNC:
c = '*';
break;
case STT_SECTION:
c = '&';
break;
case STT_FILE:
c = '/';
break;
default:
c = ' ';
break;
}
db_printf("%s%c ", sb + les->st_name, c);
} else
db_printf("%s ", sb + les->st_name);
}
}
return ENOENT;
}
#endif /* DDB */
/*
* In case we exposing the symbol table to the userland using the pseudo-
* device /dev/ksyms, it is easier to provide all the tables as one.
* However, it means we have to change all the st_name fields for the
* symbols so they match the ELF image that the userland will read
* through the device.
*
* The actual (correct) value of st_name is preserved through a global
* offset stored in the symbol table structure.
*
* Call with ksyms_lock held.
*/
static void
ksyms_sizes_calc(void)
{
struct ksyms_symtab *st;
int i, delta;
ksyms_symsz = ksyms_strsz = 0;
TAILQ_FOREACH(st, &ksyms_symtabs, sd_queue) {
if (__predict_false(st->sd_gone))
continue;
delta = ksyms_strsz - st->sd_usroffset;
if (delta != 0) {
for (i = 0; i < st->sd_symsize/sizeof(Elf_Sym); i++)
st->sd_symstart[i].st_name += delta;
st->sd_usroffset = ksyms_strsz;
}
ksyms_symsz += st->sd_symsize;
ksyms_strsz += st->sd_strsize;
}
}
static void
ksyms_fill_note(void)
{
int32_t *note = ksyms_hdr.kh_note;
note[0] = ELF_NOTE_NETBSD_NAMESZ;
note[1] = ELF_NOTE_NETBSD_DESCSZ;
note[2] = ELF_NOTE_TYPE_NETBSD_TAG;
memcpy(&note[3], "NetBSD\0", 8);
note[5] = __NetBSD_Version__;
}
static void
ksyms_hdr_init(const void *hdraddr)
{
/* Copy the loaded elf exec header */
memcpy(&ksyms_hdr.kh_ehdr, hdraddr, sizeof(Elf_Ehdr));
/* Set correct program/section header sizes, offsets and numbers */
ksyms_hdr.kh_ehdr.e_phoff = offsetof(struct ksyms_hdr, kh_phdr[0]);
ksyms_hdr.kh_ehdr.e_phentsize = sizeof(Elf_Phdr);
ksyms_hdr.kh_ehdr.e_phnum = NPRGHDR;
ksyms_hdr.kh_ehdr.e_shoff = offsetof(struct ksyms_hdr, kh_shdr[0]);
ksyms_hdr.kh_ehdr.e_shentsize = sizeof(Elf_Shdr);
ksyms_hdr.kh_ehdr.e_shnum = NSECHDR;
ksyms_hdr.kh_ehdr.e_shstrndx = SHSTRTAB;
/* Text/data - fake */
ksyms_hdr.kh_phdr[0].p_type = PT_LOAD;
ksyms_hdr.kh_phdr[0].p_memsz = (unsigned long)-1L;
ksyms_hdr.kh_phdr[0].p_flags = PF_R | PF_X | PF_W;
#define SHTCOPY(name) strlcpy(&ksyms_hdr.kh_strtab[offs], (name), \
sizeof(ksyms_hdr.kh_strtab) - offs), offs += sizeof(name)
uint32_t offs = 1;
/* First section header ".note.netbsd.ident" */
ksyms_hdr.kh_shdr[SHNOTE].sh_name = offs;
ksyms_hdr.kh_shdr[SHNOTE].sh_type = SHT_NOTE;
ksyms_hdr.kh_shdr[SHNOTE].sh_offset =
offsetof(struct ksyms_hdr, kh_note[0]);
ksyms_hdr.kh_shdr[SHNOTE].sh_size = sizeof(ksyms_hdr.kh_note);
ksyms_hdr.kh_shdr[SHNOTE].sh_addralign = sizeof(int);
SHTCOPY(".note.netbsd.ident");
ksyms_fill_note();
/* Second section header; ".symtab" */
ksyms_hdr.kh_shdr[SYMTAB].sh_name = offs;
ksyms_hdr.kh_shdr[SYMTAB].sh_type = SHT_SYMTAB;
ksyms_hdr.kh_shdr[SYMTAB].sh_offset = sizeof(struct ksyms_hdr);
/* ksyms_hdr.kh_shdr[SYMTAB].sh_size = filled in at open */
ksyms_hdr.kh_shdr[SYMTAB].sh_link = STRTAB; /* Corresponding strtab */
ksyms_hdr.kh_shdr[SYMTAB].sh_addralign = sizeof(long);
ksyms_hdr.kh_shdr[SYMTAB].sh_entsize = sizeof(Elf_Sym);
SHTCOPY(".symtab");
/* Third section header; ".strtab" */
ksyms_hdr.kh_shdr[STRTAB].sh_name = offs;
ksyms_hdr.kh_shdr[STRTAB].sh_type = SHT_STRTAB;
/* ksyms_hdr.kh_shdr[STRTAB].sh_offset = filled in at open */
/* ksyms_hdr.kh_shdr[STRTAB].sh_size = filled in at open */
ksyms_hdr.kh_shdr[STRTAB].sh_addralign = sizeof(char);
SHTCOPY(".strtab");
/* Fourth section, ".shstrtab" */
ksyms_hdr.kh_shdr[SHSTRTAB].sh_name = offs;
ksyms_hdr.kh_shdr[SHSTRTAB].sh_type = SHT_STRTAB;
ksyms_hdr.kh_shdr[SHSTRTAB].sh_offset =
offsetof(struct ksyms_hdr, kh_strtab);
ksyms_hdr.kh_shdr[SHSTRTAB].sh_size = SHSTRSIZ;
ksyms_hdr.kh_shdr[SHSTRTAB].sh_addralign = sizeof(char);
SHTCOPY(".shstrtab");
/* Fifth section, ".bss". All symbols reside here. */
ksyms_hdr.kh_shdr[SHBSS].sh_name = offs;
ksyms_hdr.kh_shdr[SHBSS].sh_type = SHT_NOBITS;
ksyms_hdr.kh_shdr[SHBSS].sh_offset = 0;
ksyms_hdr.kh_shdr[SHBSS].sh_size = (unsigned long)-1L;
ksyms_hdr.kh_shdr[SHBSS].sh_addralign = PAGE_SIZE;
ksyms_hdr.kh_shdr[SHBSS].sh_flags = SHF_ALLOC | SHF_EXECINSTR;
SHTCOPY(".bss");
/* Sixth section header; ".SUNW_ctf" */
ksyms_hdr.kh_shdr[SHCTF].sh_name = offs;
ksyms_hdr.kh_shdr[SHCTF].sh_type = SHT_PROGBITS;
/* ksyms_hdr.kh_shdr[SHCTF].sh_offset = filled in at open */
/* ksyms_hdr.kh_shdr[SHCTF].sh_size = filled in at open */
ksyms_hdr.kh_shdr[SHCTF].sh_link = SYMTAB; /* Corresponding symtab */
ksyms_hdr.kh_shdr[SHCTF].sh_addralign = sizeof(char);
SHTCOPY(".SUNW_ctf");
}
static int
ksymsopen(dev_t dev, int oflags, int devtype, struct lwp *l)
{
if (minor(dev) != 0 || !ksyms_loaded)
return ENXIO;
/*
* Create a "snapshot" of the kernel symbol table. Setting
* ksyms_isopen will prevent symbol tables from being freed.
*/
mutex_enter(&ksyms_lock);
ksyms_hdr.kh_shdr[SYMTAB].sh_size = ksyms_symsz;
ksyms_hdr.kh_shdr[SYMTAB].sh_info = ksyms_symsz / sizeof(Elf_Sym);
ksyms_hdr.kh_shdr[STRTAB].sh_offset = ksyms_symsz +
ksyms_hdr.kh_shdr[SYMTAB].sh_offset;
ksyms_hdr.kh_shdr[STRTAB].sh_size = ksyms_strsz;
ksyms_hdr.kh_shdr[SHCTF].sh_offset = ksyms_strsz +
ksyms_hdr.kh_shdr[STRTAB].sh_offset;
ksyms_hdr.kh_shdr[SHCTF].sh_size = ksyms_ctfsz;
ksyms_isopen = true;
mutex_exit(&ksyms_lock);
return 0;
}
static int
ksymsclose(dev_t dev, int oflags, int devtype, struct lwp *l)
{
struct ksyms_symtab *st, *next;
bool resize;
/* Discard references to symbol tables. */
mutex_enter(&ksyms_lock);
ksyms_isopen = false;
resize = false;
for (st = TAILQ_FIRST(&ksyms_symtabs); st != NULL; st = next) {
next = TAILQ_NEXT(st, sd_queue);
if (st->sd_gone) {
TAILQ_REMOVE(&ksyms_symtabs, st, sd_queue);
kmem_free(st->sd_nmap,
st->sd_nmapsize * sizeof(uint32_t));
kmem_free(st, sizeof(*st));
resize = true;
}
}
if (resize)
ksyms_sizes_calc();
mutex_exit(&ksyms_lock);
return 0;
}
static int
ksymsread(dev_t dev, struct uio *uio, int ioflag)
{
struct ksyms_symtab *st;
size_t filepos, inpos, off;
int error;
/*
* First: Copy out the ELF header. XXX Lose if ksymsopen()
* occurs during read of the header.
*/
off = uio->uio_offset;
if (off < sizeof(struct ksyms_hdr)) {
error = uiomove((char *)&ksyms_hdr + off,
sizeof(struct ksyms_hdr) - off, uio);
if (error != 0)
return error;
}
/*
* Copy out the symbol table.
*/
filepos = sizeof(struct ksyms_hdr);
TAILQ_FOREACH(st, &ksyms_symtabs, sd_queue) {
if (__predict_false(st->sd_gone))
continue;
if (uio->uio_resid == 0)
return 0;
if (uio->uio_offset <= st->sd_symsize + filepos) {
inpos = uio->uio_offset - filepos;
error = uiomove((char *)st->sd_symstart + inpos,
st->sd_symsize - inpos, uio);
if (error != 0)
return error;
}
filepos += st->sd_symsize;
}
/*
* Copy out the string table
*/
KASSERT(filepos == sizeof(struct ksyms_hdr) +
ksyms_hdr.kh_shdr[SYMTAB].sh_size);
TAILQ_FOREACH(st, &ksyms_symtabs, sd_queue) {
if (__predict_false(st->sd_gone))
continue;
if (uio->uio_resid == 0)
return 0;
if (uio->uio_offset <= st->sd_strsize + filepos) {
inpos = uio->uio_offset - filepos;
error = uiomove((char *)st->sd_strstart + inpos,
st->sd_strsize - inpos, uio);
if (error != 0)
return error;
}
filepos += st->sd_strsize;
}
/*
* Copy out the CTF table.
*/
st = TAILQ_FIRST(&ksyms_symtabs);
if (st->sd_ctfstart != NULL) {
if (uio->uio_resid == 0)
return 0;
if (uio->uio_offset <= st->sd_ctfsize + filepos) {
inpos = uio->uio_offset - filepos;
error = uiomove((char *)st->sd_ctfstart + inpos,
st->sd_ctfsize - inpos, uio);
if (error != 0)
return error;
}
filepos += st->sd_ctfsize;
}
return 0;
}
static int
ksymswrite(dev_t dev, struct uio *uio, int ioflag)
{
return EROFS;
}
__CTASSERT(offsetof(struct ksyms_ogsymbol, kg_name) == offsetof(struct ksyms_gsymbol, kg_name));
__CTASSERT(offsetof(struct ksyms_gvalue, kv_name) == offsetof(struct ksyms_gsymbol, kg_name));
static int
ksymsioctl(dev_t dev, u_long cmd, void *data, int fflag, struct lwp *l)
{
struct ksyms_ogsymbol *okg = (struct ksyms_ogsymbol *)data;
struct ksyms_gsymbol *kg = (struct ksyms_gsymbol *)data;
struct ksyms_gvalue *kv = (struct ksyms_gvalue *)data;
struct ksyms_symtab *st;
Elf_Sym *sym = NULL, copy;
unsigned long val;
int error = 0;
char *str = NULL;
int len;
/* Read ksyms_maxlen only once while not holding the lock. */
len = ksyms_maxlen;
if (cmd == OKIOCGVALUE || cmd == OKIOCGSYMBOL ||
cmd == KIOCGVALUE || cmd == KIOCGSYMBOL) {
str = kmem_alloc(len, KM_SLEEP);
if ((error = copyinstr(kg->kg_name, str, len, NULL)) != 0) {
kmem_free(str, len);
return error;
}
}
switch (cmd) {
case OKIOCGVALUE:
/*
* Use the in-kernel symbol lookup code for fast
* retreival of a value.
*/
error = ksyms_getval(NULL, str, &val, KSYMS_EXTERN);
if (error == 0)
error = copyout(&val, okg->kg_value, sizeof(long));
kmem_free(str, len);
break;
case OKIOCGSYMBOL:
/*
* Use the in-kernel symbol lookup code for fast
* retreival of a symbol.
*/
mutex_enter(&ksyms_lock);
TAILQ_FOREACH(st, &ksyms_symtabs, sd_queue) {
if (st->sd_gone)
continue;
if ((sym = findsym(str, st, KSYMS_ANY)) == NULL)
continue;
#ifdef notdef
/* Skip if bad binding */
if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL) {
sym = NULL;
continue;
}
#endif
break;
}
if (sym != NULL) {
memcpy(&copy, sym, sizeof(copy));
mutex_exit(&ksyms_lock);
error = copyout(&copy, okg->kg_sym, sizeof(Elf_Sym));
} else {
mutex_exit(&ksyms_lock);
error = ENOENT;
}
kmem_free(str, len);
break;
case KIOCGVALUE:
/*
* Use the in-kernel symbol lookup code for fast
* retreival of a value.
*/
error = ksyms_getval(NULL, str, &val, KSYMS_EXTERN);
if (error == 0)
kv->kv_value = val;
kmem_free(str, len);
break;
case KIOCGSYMBOL:
/*
* Use the in-kernel symbol lookup code for fast
* retreival of a symbol.
*/
mutex_enter(&ksyms_lock);
TAILQ_FOREACH(st, &ksyms_symtabs, sd_queue) {
if (st->sd_gone)
continue;
if ((sym = findsym(str, st, KSYMS_ANY)) == NULL)
continue;
#ifdef notdef
/* Skip if bad binding */
if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL) {
sym = NULL;
continue;
}
#endif
break;
}
if (sym != NULL) {
kg->kg_sym = *sym;
} else {
error = ENOENT;
}
mutex_exit(&ksyms_lock);
kmem_free(str, len);
break;
case KIOCGSIZE:
/*
* Get total size of symbol table.
*/
mutex_enter(&ksyms_lock);
*(int *)data = ksyms_strsz + ksyms_symsz +
sizeof(struct ksyms_hdr);
mutex_exit(&ksyms_lock);
break;
default:
error = ENOTTY;
break;
}
return error;
}
const struct cdevsw ksyms_cdevsw = {
.d_open = ksymsopen,
.d_close = ksymsclose,
.d_read = ksymsread,
.d_write = ksymswrite,
.d_ioctl = ksymsioctl,
.d_stop = nullstop,
.d_tty = notty,
.d_poll = nopoll,
.d_mmap = nommap,
.d_kqfilter = nullkqfilter,
.d_discard = nodiscard,
.d_flag = D_OTHER | D_MPSAFE
};
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