The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_ksyms.c

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    1 /*      $NetBSD: kern_ksyms.c,v 1.21 2004/02/19 03:42:01 matt Exp $     */
    2 /*
    3  * Copyright (c) 2001, 2003 Anders Magnusson (ragge@ludd.luth.se).
    4  * All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    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  * 3. The name of the author may not be used to endorse or promote products
   15  *    derived from this software without specific prior written permission
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   27  */
   28 
   29 /*
   30  * Code to deal with in-kernel symbol table management + /dev/ksyms.
   31  *
   32  * For each loaded module the symbol table info is kept track of by a
   33  * struct, placed in a circular list. The first entry is the kernel
   34  * symbol table.
   35  */
   36 
   37 /*
   38  * TODO:
   39  *      Change the ugly way of adding new symbols (comes with linker)
   40  *      Add kernel locking stuff.
   41  *      (Ev) add support for poll.
   42  *      (Ev) fix support for mmap.
   43  *
   44  *      Export ksyms internal logic for use in post-mortem debuggers?
   45  *        Need to move struct symtab to ksyms.h for that.
   46  */
   47 
   48 #include <sys/cdefs.h>
   49 __KERNEL_RCSID(0, "$NetBSD: kern_ksyms.c,v 1.21 2004/02/19 03:42:01 matt Exp $");
   50 
   51 #ifdef _KERNEL
   52 #include "opt_ddb.h"
   53 #include "opt_ddbparam.h"       /* for SYMTAB_SPACE */
   54 #endif
   55 
   56 #include <sys/param.h>
   57 #include <sys/errno.h>
   58 #include <sys/queue.h>
   59 #include <sys/exec.h>
   60 #include <sys/systm.h>
   61 #include <sys/conf.h>
   62 #include <sys/device.h>
   63 #include <sys/malloc.h>
   64 #include <sys/proc.h>
   65 
   66 #include <machine/elf_machdep.h> /* XXX */
   67 #define ELFSIZE ARCH_ELFSIZE
   68 
   69 #include <sys/exec_elf.h>
   70 #include <sys/ksyms.h>
   71 
   72 #include <lib/libkern/libkern.h>
   73 
   74 #ifdef DDB
   75 #include <ddb/db_output.h>
   76 #endif
   77 
   78 #include "ksyms.h"
   79 
   80 static int ksymsinited = 0;
   81 
   82 #if NKSYMS
   83 static void ksyms_hdr_init(caddr_t hdraddr);
   84 static void ksyms_sizes_calc(void);
   85 static int ksyms_isopen;
   86 static int ksyms_maxlen;
   87 #endif
   88 
   89 #ifdef KSYMS_DEBUG
   90 #define FOLLOW_CALLS            1
   91 #define FOLLOW_MORE_CALLS       2
   92 #define FOLLOW_DEVKSYMS         4
   93 static int ksyms_debug;
   94 #endif
   95 
   96 #if NKSYMS
   97 dev_type_open(ksymsopen);
   98 dev_type_close(ksymsclose);
   99 dev_type_read(ksymsread);
  100 dev_type_write(ksymswrite);
  101 dev_type_ioctl(ksymsioctl);
  102 
  103 const struct cdevsw ksyms_cdevsw = {
  104         ksymsopen, ksymsclose, ksymsread, ksymswrite, ksymsioctl,
  105         nullstop, notty, nopoll, nommap, nullkqfilter, DV_DULL
  106 };
  107 #endif
  108 
  109 #ifdef SYMTAB_SPACE
  110 #define         SYMTAB_FILLER   "|This is the symbol table!"
  111 
  112 char            db_symtab[SYMTAB_SPACE] = SYMTAB_FILLER;
  113 int             db_symtabsize = SYMTAB_SPACE;
  114 #endif
  115 
  116 /*
  117  * Store the different symbol tables in a double-linked list.
  118  */
  119 struct symtab {
  120         CIRCLEQ_ENTRY(symtab) sd_queue;
  121         const char *sd_name;    /* Name of this table */
  122         Elf_Sym *sd_symstart;   /* Address of symbol table */
  123         caddr_t sd_strstart;    /* Adderss of corresponding string table */
  124         int sd_usroffset;       /* Real address for userspace */
  125         int sd_symsize;         /* Size in bytes of symbol table */
  126         int sd_strsize;         /* Size of string table */
  127         int *sd_symnmoff;       /* Used when calculating the name offset */
  128 };
  129 
  130 static CIRCLEQ_HEAD(, symtab) symtab_queue =
  131     CIRCLEQ_HEAD_INITIALIZER(symtab_queue);
  132 
  133 static struct symtab kernel_symtab;
  134 
  135 #define USE_PTREE
  136 #ifdef USE_PTREE
  137 /*
  138  * Patricia-tree-based lookup structure for the in-kernel global symbols.
  139  * Based on a design by Mikael Sundstrom, msm@sm.luth.se.
  140  */
  141 struct ptree {
  142         int16_t bitno;
  143         int16_t lr[2];
  144 } *symb;
  145 static int16_t baseidx;
  146 static int treex = 1;
  147 
  148 #define P_BIT(key, bit) ((key[bit >> 3] >> (bit & 7)) & 1)
  149 #define STRING(idx) kernel_symtab.sd_symstart[idx].st_name + \
  150                         kernel_symtab.sd_strstart
  151 
  152 /*
  153  * Walk down the tree until a terminal node is found.
  154  */
  155 static int
  156 symbol_traverse(char *key)
  157 {
  158         int16_t nb, rbit = baseidx;
  159 
  160         while (rbit > 0) {
  161                 nb = symb[rbit].bitno;
  162                 rbit = symb[rbit].lr[P_BIT(key, nb)];
  163         }
  164         return -rbit;
  165 }
  166 
  167 static int
  168 ptree_add(char *key, int val)
  169 {
  170         int idx;
  171         int nix, cix, bit, rbit, sb, lastrbit, svbit = 0, ix;
  172         char *m, *k;
  173 
  174         if (baseidx == 0) {
  175                 baseidx = -val;
  176                 return 0; /* First element */
  177         }
  178 
  179         /* Get string to match against */
  180         idx = symbol_traverse(key);
  181 
  182         /* Find first mismatching bit */
  183         m = STRING(idx);
  184         k = key;
  185         if (strcmp(m, k) == 0)
  186                 return 1;
  187 
  188         for (cix = 0; *m && *k && *m == *k; m++, k++, cix += 8)
  189                 ;
  190         ix = ffs((int)*m ^ (int)*k) - 1;
  191         cix += ix;
  192 
  193         /* Create new node */
  194         nix = treex++;
  195         bit = P_BIT(key, cix);
  196         symb[nix].bitno = cix;
  197         symb[nix].lr[bit] = -val;
  198 
  199         /* Find where to insert node */
  200         rbit = baseidx;
  201         lastrbit = 0;
  202         for (;;) {
  203                 if (rbit < 0)
  204                         break;
  205                 sb = symb[rbit].bitno;
  206                 if (sb > cix)
  207                         break;
  208                 if (sb == cix)
  209                         printf("symb[rbit].bitno == cix!!!\n");
  210                 lastrbit = rbit;
  211                 svbit = P_BIT(key, sb);
  212                 rbit = symb[rbit].lr[svbit];
  213         }
  214 
  215         /* Do the actual insertion */
  216         if (lastrbit == 0) {
  217                 /* first element */
  218                 symb[nix].lr[!bit] = baseidx;
  219                 baseidx = nix;
  220         } else {
  221                 symb[nix].lr[!bit] = rbit;
  222                 symb[lastrbit].lr[svbit] = nix;
  223         }
  224         return 0;
  225 }
  226 
  227 static int
  228 ptree_find(char *key)
  229 {
  230         int idx;
  231 
  232         if (baseidx == 0)
  233                 return 0;
  234         idx = symbol_traverse(key);
  235 
  236         if (strcmp(key, STRING(idx)) == 0)
  237                 return idx;
  238         return 0;
  239 }
  240 
  241 static void
  242 ptree_gen(char *off, struct symtab *tab)
  243 {
  244         Elf_Sym *sym;
  245         int i, nsym;
  246 
  247         if (off != NULL)
  248                 symb = (struct ptree *)ALIGN(off);
  249         else
  250                 symb = malloc((tab->sd_symsize/sizeof(Elf_Sym)) *
  251                     sizeof(struct ptree), M_DEVBUF, M_WAITOK);
  252         symb--; /* sym index won't be 0 */
  253 
  254         sym = tab->sd_symstart;
  255         if ((nsym = tab->sd_symsize/sizeof(Elf_Sym)) > INT16_MAX) {
  256                 printf("Too many symbols for tree, skipping %d symbols\n",
  257                     nsym-INT16_MAX);
  258                 nsym = INT16_MAX;
  259         }
  260         for (i = 1; i < nsym; i++) {
  261                 if (ELF_ST_BIND(sym[i].st_info) != STB_GLOBAL)
  262                         continue;
  263                 ptree_add(tab->sd_strstart+sym[i].st_name, i);
  264         }
  265 }
  266 #endif
  267 
  268 /*
  269  * Finds a certain symbol name in a certain symbol table.
  270  */
  271 static Elf_Sym *
  272 findsym(char *name, struct symtab *table, int userreq)
  273 {
  274         Elf_Sym *start = table->sd_symstart;
  275         int i, sz = table->sd_symsize/sizeof(Elf_Sym);
  276         char *np;
  277         caddr_t realstart = table->sd_strstart - (userreq ? 0 : table->sd_usroffset);
  278 
  279 #ifdef USE_PTREE
  280         if (table == &kernel_symtab && (i = ptree_find(name)) != 0)
  281                 return &start[i];
  282 #endif
  283 
  284         for (i = 0; i < sz; i++) {
  285                 np = realstart + start[i].st_name;
  286                 if (name[0] == np[0] && name[1] == np[1] &&
  287                     strcmp(name, np) == 0)
  288                         return &start[i];
  289         }
  290         return NULL;
  291 }
  292 
  293 /*
  294  * The "attach" is in reality done in ksyms_init().
  295  */
  296 void ksymsattach(int);
  297 void
  298 ksymsattach(int arg)
  299 {
  300 
  301 #ifdef USE_PTREE
  302         if (baseidx == 0)
  303                 ptree_gen(0, &kernel_symtab);
  304 #endif
  305 
  306 }
  307 
  308 /*
  309  * Add a symbol table named name.
  310  * This is intended for use when the kernel loader enters the table.
  311  */
  312 static void
  313 addsymtab(const char *name, Elf_Ehdr *ehdr, struct symtab *tab)
  314 {
  315         caddr_t start = (caddr_t)ehdr;
  316         caddr_t send;
  317         Elf_Shdr *shdr;
  318         Elf_Sym *sym, *nsym;
  319         int i, j, n, g;
  320         char *str;
  321 
  322         /* Find the symbol table and the corresponding string table. */
  323         shdr = (Elf_Shdr *)(start + ehdr->e_shoff);
  324         for (i = 1; i < ehdr->e_shnum; i++) {
  325                 if (shdr[i].sh_type != SHT_SYMTAB)
  326                         continue;
  327                 if (shdr[i].sh_offset == 0)
  328                         continue;
  329                 tab->sd_symstart = (Elf_Sym *)(start + shdr[i].sh_offset);
  330                 tab->sd_symsize = shdr[i].sh_size;
  331                 j = shdr[i].sh_link;
  332                 if (shdr[j].sh_offset == 0)
  333                         continue; /* Can this happen? */
  334                 tab->sd_strstart = start + shdr[j].sh_offset;
  335                 tab->sd_strsize = shdr[j].sh_size;
  336                 break;
  337         }
  338         tab->sd_name = name;
  339         send = tab->sd_strstart + tab->sd_strsize;
  340 
  341 #ifdef KSYMS_DEBUG
  342         printf("start %p sym %p symsz %d str %p strsz %d send %p\n",
  343             start, tab->sd_symstart, tab->sd_symsize, 
  344             tab->sd_strstart, tab->sd_strsize, send);
  345 #endif
  346 
  347         /*
  348          * Pack symbol table by removing all file name references
  349          * and overwrite the elf header.
  350          */
  351         sym = tab->sd_symstart;
  352         nsym = (Elf_Sym *)start;
  353         str = tab->sd_strstart;
  354         for (g = i = n = 0; i < tab->sd_symsize/sizeof(Elf_Sym); i++) {
  355                 if (i == 0) {
  356                         nsym[n++] = sym[i];
  357                         continue;
  358                 }
  359                 /*
  360                  * Remove useless symbols.
  361                  * Should actually remove all typeless symbols.
  362                  */
  363                 if (sym[i].st_name == 0)
  364                         continue; /* Skip nameless entries */
  365                 if (ELF_ST_TYPE(sym[i].st_info) == STT_FILE)
  366                         continue; /* Skip filenames */
  367                 if (ELF_ST_TYPE(sym[i].st_info) == STT_NOTYPE &&
  368                     sym[i].st_value == 0 &&
  369                     strcmp(str + sym[i].st_name, "*ABS*") == 0)
  370                         continue; /* XXX */
  371                 if (ELF_ST_TYPE(sym[i].st_info) == STT_NOTYPE &&
  372                     strcmp(str + sym[i].st_name, "gcc2_compiled.") == 0)
  373                         continue; /* XXX */
  374 
  375 #ifndef DDB
  376                 /* Only need global symbols */
  377                 if (ELF_ST_BIND(sym[i].st_info) != STB_GLOBAL)
  378                         continue;
  379 #endif
  380 
  381                 /* Save symbol. Set it as an absolute offset */
  382                 nsym[n] = sym[i];
  383                 nsym[n].st_shndx = SHN_ABS;
  384                 if (ELF_ST_BIND(nsym[n].st_info) == STB_GLOBAL)
  385                         g++;
  386 #if NKSYMS
  387                 j = strlen(nsym[n].st_name + tab->sd_strstart) + 1;
  388                 if (j > ksyms_maxlen)
  389                         ksyms_maxlen = j;
  390 #endif
  391                 n++;
  392 
  393         }
  394         tab->sd_symstart = nsym;
  395         tab->sd_symsize = n * sizeof(Elf_Sym);
  396 
  397 #ifdef notyet
  398         /*
  399          * Remove left-over strings.
  400          */
  401         sym = tab->sd_symstart;
  402         str = (caddr_t)tab->sd_symstart + tab->sd_symsize;
  403         str[0] = 0;
  404         n = 1;
  405         for (i = 1; i < tab->sd_symsize/sizeof(Elf_Sym); i++) {
  406                 strcpy(str + n, tab->sd_strstart + sym[i].st_name);
  407                 sym[i].st_name = n;
  408                 n += strlen(str+n) + 1;
  409         }
  410         tab->sd_strstart = str;
  411         tab->sd_strsize = n;
  412 
  413 #ifdef KSYMS_DEBUG
  414         printf("str %p strsz %d send %p\n", str, n, send);
  415 #endif
  416 #endif
  417 
  418         CIRCLEQ_INSERT_HEAD(&symtab_queue, tab, sd_queue);
  419 
  420 #ifdef notyet
  421 #ifdef USE_PTREE
  422         /* Try to use the freed space, if possible */
  423         if (send - str - n > g * sizeof(struct ptree))
  424                 ptree_gen(str + n, tab);
  425 #endif
  426 #endif
  427 }
  428 
  429 /*
  430  * Setup the kernel symbol table stuff.
  431  */
  432 void
  433 ksyms_init(int symsize, void *start, void *end)
  434 {
  435         Elf_Ehdr *ehdr;
  436 
  437 #ifdef SYMTAB_SPACE
  438         if (symsize <= 0 &&
  439             strncmp(db_symtab, SYMTAB_FILLER, sizeof(SYMTAB_FILLER))) {
  440                 symsize = db_symtabsize;
  441                 start = db_symtab;
  442                 end = db_symtab + db_symtabsize;
  443         }
  444 #endif
  445         if (symsize <= 0) {
  446                 printf("[ Kernel symbol table missing! ]\n");
  447                 return;
  448         }
  449 
  450         /* Sanity check */
  451         if (ALIGNED_POINTER(start, long) == 0) {
  452                 printf("[ Kernel symbol table has bad start address %p ]\n",
  453                     start);
  454                 return;
  455         }
  456 
  457         ehdr = (Elf_Ehdr *)start;
  458 
  459         /* check if this is a valid ELF header */
  460         /* No reason to verify arch type, the kernel is actually running! */
  461         if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) ||
  462             ehdr->e_ident[EI_CLASS] != ELFCLASS ||
  463             ehdr->e_version > 1) {
  464 #ifdef notyet /* DDB */
  465                 if (ddb_init(symsize, start, end))
  466                         return; /* old-style symbol table */
  467 #endif
  468                 printf("[ Kernel symbol table invalid! ]\n");
  469                 return; /* nothing to do */
  470         }
  471 
  472 #if NKSYMS
  473         /* Loaded header will be scratched in addsymtab */
  474         ksyms_hdr_init(start);
  475 #endif
  476 
  477         addsymtab("netbsd", ehdr, &kernel_symtab);
  478 
  479 #if NKSYMS
  480         ksyms_sizes_calc();
  481 #endif
  482 
  483         ksymsinited = 1;
  484 
  485 #ifdef DEBUG
  486         printf("Loaded initial symtab at %p, strtab at %p, # entries %ld\n",
  487             kernel_symtab.sd_symstart, kernel_symtab.sd_strstart,
  488             (long)kernel_symtab.sd_symsize/sizeof(Elf_Sym));
  489 #endif
  490 }
  491 
  492 /*
  493  * Get the value associated with a symbol.
  494  * "mod" is the module name, or null if any module. 
  495  * "sym" is the symbol name.
  496  * "val" is a pointer to the corresponding value, if call succeeded.
  497  * Returns 0 if success or ENOENT if no such entry.
  498  */
  499 int
  500 ksyms_getval(const char *mod, char *sym, unsigned long *val, int type, int userreq)
  501 {
  502         struct symtab *st;
  503         Elf_Sym *es;
  504 
  505         if (ksymsinited == 0)
  506                 return ENOENT;
  507 
  508 #ifdef KSYMS_DEBUG
  509         if (ksyms_debug & FOLLOW_CALLS)
  510                 printf("ksyms_getval: mod %s sym %s valp %p\n", mod, sym, val);
  511 #endif
  512 
  513         CIRCLEQ_FOREACH(st, &symtab_queue, sd_queue) {
  514                 if (mod && strcmp(st->sd_name, mod))
  515                         continue;
  516                 if ((es = findsym(sym, st, userreq)) == NULL)
  517                         continue;
  518 
  519                 /* Skip if bad binding */
  520                 if (type == KSYMS_EXTERN &&
  521                     ELF_ST_BIND(es->st_info) != STB_GLOBAL)
  522                         continue;
  523 
  524                 if (val)
  525                         *val = es->st_value;
  526                 return 0;
  527         }
  528         return ENOENT;
  529 }
  530 
  531 /*
  532  * Get "mod" and "symbol" associated with an address.
  533  * Returns 0 if success or ENOENT if no such entry.
  534  */
  535 int
  536 ksyms_getname(const char **mod, char **sym, vaddr_t v, int f)
  537 {
  538         struct symtab *st;
  539         Elf_Sym *les, *es = NULL;
  540         vaddr_t laddr = 0;
  541         const char *lmod = NULL;
  542         char *stable = NULL;
  543         int type, i, sz;
  544 
  545         if (ksymsinited == 0)
  546                 return ENOENT;
  547 
  548         CIRCLEQ_FOREACH(st, &symtab_queue, sd_queue) {
  549                 sz = st->sd_symsize/sizeof(Elf_Sym);
  550                 for (i = 0; i < sz; i++) {
  551                         les = st->sd_symstart + i;
  552                         type = ELF_ST_TYPE(les->st_info);
  553 
  554                         if ((f & KSYMS_PROC) && (type != STT_FUNC))
  555                                 continue;
  556 
  557                         if (type == STT_NOTYPE)
  558                                 continue;
  559 
  560                         if (((f & KSYMS_ANY) == 0) &&
  561                             (type != STT_FUNC) && (type != STT_OBJECT))
  562                                 continue;
  563 
  564                         if ((les->st_value <= v) && (les->st_value > laddr)) {
  565                                 laddr = les->st_value;
  566                                 es = les;
  567                                 lmod = st->sd_name;
  568                                 stable = st->sd_strstart - st->sd_usroffset;
  569                         }
  570                 }
  571         }
  572         if (es == NULL)
  573                 return ENOENT;
  574         if ((f & KSYMS_EXACT) && (v != es->st_value))
  575                 return ENOENT;
  576         if (mod)
  577                 *mod = lmod;
  578         if (sym)
  579                 *sym = stable + es->st_name;
  580         return 0;
  581 }
  582 
  583 #if NKSYMS
  584 static int symsz, strsz;
  585 
  586 static void
  587 ksyms_sizes_calc(void)
  588 {               
  589         struct symtab *st; 
  590         int i;
  591 
  592         symsz = strsz = 0;
  593         CIRCLEQ_FOREACH(st, &symtab_queue, sd_queue) {
  594                 if (st != &kernel_symtab) {
  595                         for (i = 0; i < st->sd_symsize/sizeof(Elf_Sym); i++)
  596                                 st->sd_symstart[i].st_name =
  597                                     strsz + st->sd_symnmoff[i];
  598                         st->sd_usroffset = strsz;
  599                 }
  600                 symsz += st->sd_symsize;
  601                 strsz += st->sd_strsize;
  602         }
  603 }
  604 #endif
  605 
  606 /*
  607  * Temporary work structure for dynamic loaded symbol tables.
  608  * Will go away when in-kernel linker is in place.
  609  */
  610 
  611 struct syminfo {
  612         size_t cursyms;
  613         size_t curnamep;
  614         size_t maxsyms;
  615         size_t maxnamep;
  616         Elf_Sym *syms;
  617         int *symnmoff;
  618         char *symnames;
  619 };
  620         
  621 
  622 /*
  623  * Add a symbol to the temporary save area for symbols.
  624  * This routine will go away when the in-kernel linker is in place.
  625  */
  626 static void
  627 addsym(struct syminfo *info, const Elf_Sym *sym, const char *name,
  628        const char *mod)
  629 {
  630         int len, mlen;
  631 
  632 #ifdef KSYMS_DEBUG
  633         if (ksyms_debug & FOLLOW_MORE_CALLS)
  634                 printf("addsym: name %s val %lx\n", name, (long)sym->st_value);
  635 #endif
  636         len = strlen(name) + 1;
  637         if (mod)
  638                 mlen = 1 + strlen(mod);
  639         else
  640                 mlen = 0;
  641         if (info->cursyms == info->maxsyms || 
  642             (len + mlen + info->curnamep) > info->maxnamep) {
  643                 printf("addsym: too many symbols, skipping '%s'\n", name);
  644                 return;
  645         }
  646         strlcpy(&info->symnames[info->curnamep], name,
  647             info->maxnamep - info->curnamep);
  648         if (mlen) {
  649                 info->symnames[info->curnamep + len - 1] = '.';
  650                 strlcpy(&info->symnames[info->curnamep + len], mod,
  651                     info->maxnamep - (info->curnamep + len));
  652                 len += mlen;
  653         }
  654         info->syms[info->cursyms] = *sym;
  655         info->syms[info->cursyms].st_name = info->curnamep;
  656         info->symnmoff[info->cursyms] = info->curnamep;
  657         info->curnamep += len;
  658 #if NKSYMS
  659         if (len > ksyms_maxlen)
  660                 ksyms_maxlen = len;
  661 #endif
  662         info->cursyms++;
  663 }
  664 /*
  665  * Adds a symbol table.
  666  * "name" is the module name, "start" and "size" is where the symbol table
  667  * is located, and "type" is in which binary format the symbol table is.
  668  * New memory for keeping the symbol table is allocated in this function.
  669  * Returns 0 if success and EEXIST if the module name is in use.
  670  */
  671 static int
  672 specialsym(const char *symname)
  673 {
  674         return  !strcmp(symname, "_bss_start") ||
  675                 !strcmp(symname, "__bss_start") ||
  676                 !strcmp(symname, "_bss_end__") ||
  677                 !strcmp(symname, "__bss_end__") ||
  678                 !strcmp(symname, "_edata") ||
  679                 !strcmp(symname, "_end") ||
  680                 !strcmp(symname, "__end") ||
  681                 !strcmp(symname, "__end__") ||
  682                 !strncmp(symname, "__start_link_set_", 17) ||
  683                 !strncmp(symname, "__stop_link_set_", 16);
  684 }
  685 
  686 int
  687 ksyms_addsymtab(const char *mod, void *symstart, vsize_t symsize,
  688     char *strstart, vsize_t strsize)
  689 {
  690         Elf_Sym *sym = symstart;
  691         struct symtab *st;
  692         unsigned long rval;
  693         int i;
  694         char *name;
  695         struct syminfo info;
  696 
  697 #ifdef KSYMS_DEBUG
  698         if (ksyms_debug & FOLLOW_CALLS)
  699                 printf("ksyms_addsymtab: mod %s symsize %lx strsize %lx\n",
  700                     mod, symsize, strsize);
  701 #endif
  702 
  703 #if NKSYMS
  704         /*
  705          * Do not try to add a symbol table while someone is reading
  706          * from /dev/ksyms.
  707          */
  708         while (ksyms_isopen != 0)
  709                 tsleep(&ksyms_isopen, PWAIT, "ksyms", 0);
  710 #endif
  711 
  712         /* Check if this symtab already loaded */
  713         CIRCLEQ_FOREACH(st, &symtab_queue, sd_queue) {
  714                 if (strcmp(mod, st->sd_name) == 0)
  715                         return EEXIST;
  716         }
  717 
  718         /*
  719          * XXX - Only add a symbol if it do not exist already.
  720          * This is because of a flaw in the current LKM implementation,
  721          * these loops will be removed once the in-kernel linker is in place.
  722          */
  723         memset(&info, 0, sizeof(info));
  724         for (i = 0; i < symsize/sizeof(Elf_Sym); i++) {
  725                 char * const symname = strstart + sym[i].st_name;
  726                 if (sym[i].st_name == 0)
  727                         continue; /* Just ignore */
  728 
  729                 /* check validity of the symbol */
  730                 /* XXX - save local symbols if DDB */
  731                 if (ELF_ST_BIND(sym[i].st_info) != STB_GLOBAL)
  732                         continue;
  733                         
  734                 /* Check if the symbol exists */
  735                 if (ksyms_getval_from_kernel(NULL, symname,
  736                     &rval, KSYMS_EXTERN) == 0) {
  737                         /* Check (and complain) about differing values */
  738                         if (sym[i].st_value != rval) {
  739                                 if (specialsym(symname)) {
  740                                         info.maxsyms++;
  741                                         info.maxnamep += strlen(symname) + 1 +
  742                                             strlen(mod) + 1;
  743                                 } else {
  744                                         printf("%s: symbol '%s' redeclared with"
  745                                             " different value (%lx != %lx)\n",
  746                                             mod, symname,
  747                                             rval, (long)sym[i].st_value);
  748                                 }
  749                         }
  750                 } else {
  751                         /*
  752                          * Count this symbol
  753                          */
  754                         info.maxsyms++;
  755                         info.maxnamep += strlen(symname) + 1;
  756                 }
  757         }
  758 
  759         /*
  760          * Now that we know the sizes, malloc the structures.
  761          */
  762         info.syms = malloc(sizeof(Elf_Sym)*info.maxsyms, M_DEVBUF, M_WAITOK);
  763         info.symnames = malloc(info.maxnamep, M_DEVBUF, M_WAITOK);
  764         info.symnmoff = malloc(sizeof(int)*info.maxsyms, M_DEVBUF, M_WAITOK);
  765 
  766         /*
  767          * Now that we have the symbols, actually fill in the structures.
  768          */
  769         for (i = 0; i < symsize/sizeof(Elf_Sym); i++) {
  770                 char * const symname = strstart + sym[i].st_name;
  771                 if (sym[i].st_name == 0)
  772                         continue; /* Just ignore */
  773 
  774                 /* check validity of the symbol */
  775                 /* XXX - save local symbols if DDB */
  776                 if (ELF_ST_BIND(sym[i].st_info) != STB_GLOBAL)
  777                         continue;
  778                         
  779                 /* Check if the symbol exists */
  780                 if (ksyms_getval_from_kernel(NULL, symname,
  781                     &rval, KSYMS_EXTERN) == 0) {
  782                         if ((sym[i].st_value != rval) && specialsym(symname)) {
  783                                 addsym(&info, &sym[i], symname, mod);
  784                         }
  785                 } else
  786                         /* Ok, save this symbol */
  787                         addsym(&info, &sym[i], symname, NULL);
  788         }
  789 
  790         st = malloc(sizeof(struct symtab), M_DEVBUF, M_WAITOK);
  791         i = strlen(mod) + 1;
  792         name = malloc(i, M_DEVBUF, M_WAITOK);
  793         strlcpy(name, mod, i);
  794         st->sd_name = name;
  795         st->sd_symnmoff = info.symnmoff;
  796         st->sd_symstart = info.syms;
  797         st->sd_symsize = sizeof(Elf_Sym)*info.maxsyms;
  798         st->sd_strstart = info.symnames;
  799         st->sd_strsize = info.maxnamep;
  800 
  801         /* Make them absolute references */
  802         sym = st->sd_symstart;
  803         for (i = 0; i < st->sd_symsize/sizeof(Elf_Sym); i++)
  804                 sym[i].st_shndx = SHN_ABS;
  805 
  806         CIRCLEQ_INSERT_TAIL(&symtab_queue, st, sd_queue);
  807 #if NKSYMS
  808         ksyms_sizes_calc();
  809 #endif
  810         return 0;
  811 }
  812 
  813 /*
  814  * Remove a symbol table specified by name.
  815  * Returns 0 if success, EBUSY if device open and ENOENT if no such name.
  816  */
  817 int
  818 ksyms_delsymtab(const char *mod)
  819 {
  820         struct symtab *st;
  821         int found = 0;
  822 
  823 #if NKSYMS
  824         /*
  825          * Do not try to delete a symbol table while someone is reading
  826          * from /dev/ksyms.
  827          */
  828         while (ksyms_isopen != 0)
  829                 tsleep(&ksyms_isopen, PWAIT, "ksyms", 0);
  830 #endif
  831 
  832         CIRCLEQ_FOREACH(st, &symtab_queue, sd_queue) {
  833                 if (strcmp(mod, st->sd_name) == 0) {
  834                         found = 1;
  835                         break;
  836                 }
  837         }
  838         if (found == 0)
  839                 return ENOENT;
  840         CIRCLEQ_REMOVE(&symtab_queue, st, sd_queue);
  841         free(st->sd_symstart, M_DEVBUF);
  842         free(st->sd_strstart, M_DEVBUF);
  843         free(st->sd_symnmoff, M_DEVBUF);
  844         /* LINTED - const castaway */
  845         free((void *)st->sd_name, M_DEVBUF);
  846         free(st, M_DEVBUF);
  847 #if NKSYMS
  848         ksyms_sizes_calc();
  849 #endif
  850         return 0;
  851 }
  852 
  853 int
  854 ksyms_rensymtab(const char *old, const char *new)
  855 {
  856         struct symtab *st, *oldst = NULL;
  857         char *newstr;
  858 
  859         CIRCLEQ_FOREACH(st, &symtab_queue, sd_queue) {
  860                 if (strcmp(old, st->sd_name) == 0)
  861                         oldst = st;
  862                 if (strcmp(new, st->sd_name) == 0)
  863                         return (EEXIST);
  864         }
  865         if (oldst == NULL)
  866                 return (ENOENT);
  867 
  868         newstr = malloc(strlen(new)+1, M_DEVBUF, M_WAITOK);
  869         if (!newstr)
  870                 return (ENOMEM);
  871         strcpy(newstr, new);
  872         free((char *)oldst->sd_name, M_DEVBUF);
  873         oldst->sd_name = newstr;
  874 
  875         return (0);
  876 }
  877 
  878 #ifdef DDB
  879 
  880 /*
  881  * Keep sifting stuff here, to avoid export of ksyms internals.
  882  */
  883 int
  884 ksyms_sift(char *mod, char *sym, int mode)
  885 {
  886         struct symtab *st;
  887         char *sb;
  888         int i, sz;
  889 
  890         if (ksymsinited == 0)
  891                 return ENOENT;
  892 
  893         CIRCLEQ_FOREACH(st, &symtab_queue, sd_queue) {
  894                 if (mod && strcmp(mod, st->sd_name))
  895                         continue;
  896                 sb = st->sd_strstart;
  897 
  898                 sz = st->sd_symsize/sizeof(Elf_Sym);
  899                 for (i = 0; i < sz; i++) {
  900                         Elf_Sym *les = st->sd_symstart + i;
  901                         char c;
  902 
  903                         if (strstr(sb + les->st_name - st->sd_usroffset, sym)
  904                             == NULL)
  905                                 continue;
  906 
  907                         if (mode == 'F') {
  908                                 switch (ELF_ST_TYPE(les->st_info)) {
  909                                 case STT_OBJECT:
  910                                         c = '+';
  911                                         break;
  912                                 case STT_FUNC:
  913                                         c = '*';
  914                                         break;
  915                                 case STT_SECTION:
  916                                         c = '&';
  917                                         break;
  918                                 case STT_FILE:
  919                                         c = '/';
  920                                         break;
  921                                 default:
  922                                         c = ' ';
  923                                         break;
  924                                 }
  925                                 db_printf("%s%c ", sb + les->st_name -
  926                                     st->sd_usroffset, c);
  927                         } else
  928                                 db_printf("%s ", sb + les->st_name -
  929                                     st->sd_usroffset);
  930                 }
  931         }
  932         return ENOENT;
  933 }
  934 #endif
  935 
  936 #if NKSYMS
  937 
  938 /*
  939  * Static allocated ELF header.
  940  * Basic info is filled in at attach, sizes at open.
  941  */
  942 #define SYMTAB          1
  943 #define STRTAB          2
  944 #define SHSTRTAB        3
  945 #define NSECHDR         4
  946 
  947 #define NPRGHDR         2
  948 #define SHSTRSIZ        28
  949 
  950 static struct ksyms_hdr {
  951         Elf_Ehdr        kh_ehdr;
  952         Elf_Phdr        kh_phdr[NPRGHDR];
  953         Elf_Shdr        kh_shdr[NSECHDR];
  954         char            kh_strtab[SHSTRSIZ];
  955 } ksyms_hdr;
  956 
  957 
  958 void
  959 ksyms_hdr_init(caddr_t hdraddr)
  960 {
  961 
  962         /* Copy the loaded elf exec header */
  963         memcpy(&ksyms_hdr.kh_ehdr, hdraddr, sizeof(Elf_Ehdr));
  964 
  965         /* Set correct program/section header sizes, offsets and numbers */
  966         ksyms_hdr.kh_ehdr.e_phoff = offsetof(struct ksyms_hdr, kh_phdr[0]);
  967         ksyms_hdr.kh_ehdr.e_phentsize = sizeof(Elf_Phdr);
  968         ksyms_hdr.kh_ehdr.e_phnum = NPRGHDR;
  969         ksyms_hdr.kh_ehdr.e_shoff = offsetof(struct ksyms_hdr, kh_shdr[0]);
  970         ksyms_hdr.kh_ehdr.e_shentsize = sizeof(Elf_Shdr);
  971         ksyms_hdr.kh_ehdr.e_shnum = NSECHDR;
  972         ksyms_hdr.kh_ehdr.e_shstrndx = NSECHDR - 1; /* Last section */
  973 
  974         /*
  975          * Keep program headers zeroed (unused).
  976          * The section headers are hand-crafted.
  977          * First section is section zero.
  978          */
  979 
  980         /* Second section header; ".symtab" */
  981         ksyms_hdr.kh_shdr[SYMTAB].sh_name = 1; /* Section 3 offset */
  982         ksyms_hdr.kh_shdr[SYMTAB].sh_type = SHT_SYMTAB;
  983         ksyms_hdr.kh_shdr[SYMTAB].sh_offset = sizeof(struct ksyms_hdr);
  984 /*      ksyms_hdr.kh_shdr[SYMTAB].sh_size = filled in at open */
  985         ksyms_hdr.kh_shdr[SYMTAB].sh_link = 2; /* Corresponding strtab */
  986         ksyms_hdr.kh_shdr[SYMTAB].sh_info = 0; /* XXX */
  987         ksyms_hdr.kh_shdr[SYMTAB].sh_addralign = sizeof(long);
  988         ksyms_hdr.kh_shdr[SYMTAB].sh_entsize = sizeof(Elf_Sym);
  989 
  990         /* Third section header; ".strtab" */
  991         ksyms_hdr.kh_shdr[STRTAB].sh_name = 9; /* Section 3 offset */
  992         ksyms_hdr.kh_shdr[STRTAB].sh_type = SHT_STRTAB;
  993 /*      ksyms_hdr.kh_shdr[STRTAB].sh_offset = filled in at open */
  994 /*      ksyms_hdr.kh_shdr[STRTAB].sh_size = filled in at open */
  995 /*      ksyms_hdr.kh_shdr[STRTAB].sh_link = kept zero */
  996         ksyms_hdr.kh_shdr[STRTAB].sh_info = 0;
  997         ksyms_hdr.kh_shdr[STRTAB].sh_addralign = sizeof(char);
  998         ksyms_hdr.kh_shdr[STRTAB].sh_entsize = 0;
  999 
 1000         /* Fourth section, ".shstrtab" */
 1001         ksyms_hdr.kh_shdr[SHSTRTAB].sh_name = 17; /* This section name offset */
 1002         ksyms_hdr.kh_shdr[SHSTRTAB].sh_type = SHT_STRTAB;
 1003         ksyms_hdr.kh_shdr[SHSTRTAB].sh_offset =
 1004             offsetof(struct ksyms_hdr, kh_strtab);
 1005         ksyms_hdr.kh_shdr[SHSTRTAB].sh_size = SHSTRSIZ;
 1006         ksyms_hdr.kh_shdr[SHSTRTAB].sh_addralign = sizeof(char);
 1007 
 1008         /* Set section names */
 1009         strlcpy(&ksyms_hdr.kh_strtab[1], ".symtab",
 1010             sizeof(ksyms_hdr.kh_strtab) - 1);
 1011         strlcpy(&ksyms_hdr.kh_strtab[9], ".strtab",
 1012             sizeof(ksyms_hdr.kh_strtab) - 9);
 1013         strlcpy(&ksyms_hdr.kh_strtab[17], ".shstrtab",
 1014             sizeof(ksyms_hdr.kh_strtab) - 17);
 1015 };
 1016 
 1017 int
 1018 ksymsopen(dev_t dev, int oflags, int devtype, struct proc *p)
 1019 {
 1020 
 1021         if (minor(dev))
 1022                 return ENXIO;
 1023         if (ksymsinited == 0)
 1024                 return ENXIO;
 1025 
 1026         ksyms_hdr.kh_shdr[SYMTAB].sh_size = symsz;
 1027         ksyms_hdr.kh_shdr[STRTAB].sh_offset = symsz +
 1028             ksyms_hdr.kh_shdr[SYMTAB].sh_offset;
 1029         ksyms_hdr.kh_shdr[STRTAB].sh_size = strsz;
 1030         ksyms_isopen = 1;
 1031 
 1032 #ifdef KSYMS_DEBUG
 1033         if (ksyms_debug & FOLLOW_DEVKSYMS)
 1034                 printf("ksymsopen: symsz 0x%x strsz 0x%x\n", symsz, strsz);
 1035 #endif
 1036 
 1037         return 0;
 1038 }
 1039 
 1040 int
 1041 ksymsclose(dev_t dev, int oflags, int devtype, struct proc *p)
 1042 {
 1043 
 1044 #ifdef KSYMS_DEBUG
 1045         if (ksyms_debug & FOLLOW_DEVKSYMS)
 1046                 printf("ksymsclose\n");
 1047 #endif
 1048 
 1049         ksyms_isopen = 0;
 1050         wakeup(&ksyms_isopen);
 1051         return 0;
 1052 }
 1053 
 1054 #define HDRSIZ  sizeof(struct ksyms_hdr)
 1055 
 1056 int
 1057 ksymsread(dev_t dev, struct uio *uio, int ioflag)
 1058 {
 1059         struct symtab *st;
 1060         size_t filepos, inpos, off;
 1061 
 1062 #ifdef KSYMS_DEBUG
 1063         if (ksyms_debug & FOLLOW_DEVKSYMS)
 1064                 printf("ksymsread: offset 0x%llx resid 0x%lx\n",
 1065                     (long long)uio->uio_offset, uio->uio_resid);
 1066 #endif
 1067 
 1068         off = uio->uio_offset;
 1069         if (off >= (strsz + symsz + HDRSIZ))
 1070                 return 0; /* End of symtab */
 1071         /*
 1072          * First: Copy out the ELF header.
 1073          */
 1074         if (off < HDRSIZ)
 1075                 uiomove((char *)&ksyms_hdr + off, HDRSIZ - off, uio);
 1076 
 1077         /*
 1078          * Copy out the symbol table.
 1079          */
 1080         filepos = HDRSIZ;
 1081         CIRCLEQ_FOREACH(st, &symtab_queue, sd_queue) {
 1082                 if (uio->uio_resid == 0)
 1083                         return 0;
 1084                 if (uio->uio_offset <= st->sd_symsize + filepos) {
 1085                         inpos = uio->uio_offset - filepos;
 1086                         uiomove((char *)st->sd_symstart + inpos,
 1087                            st->sd_symsize - inpos, uio);
 1088                 }
 1089                 filepos += st->sd_symsize;
 1090         }
 1091 
 1092         if (filepos != HDRSIZ + symsz)
 1093                 panic("ksymsread: unsunc");
 1094 
 1095         /*
 1096          * Copy out the string table
 1097          */
 1098         CIRCLEQ_FOREACH(st, &symtab_queue, sd_queue) {
 1099                 if (uio->uio_resid == 0)
 1100                         return 0;
 1101                 if (uio->uio_offset <= st->sd_strsize + filepos) {
 1102                         inpos = uio->uio_offset - filepos;
 1103                         uiomove((char *)st->sd_strstart + inpos,
 1104                            st->sd_strsize - inpos, uio);
 1105                 }
 1106                 filepos += st->sd_strsize;
 1107         }
 1108         return 0;
 1109 }
 1110 
 1111 int
 1112 ksymswrite(dev_t dev, struct uio *uio, int ioflag)
 1113 {
 1114         return EROFS;
 1115 }
 1116 
 1117 int
 1118 ksymsioctl(dev_t dev, u_long cmd, caddr_t data, int fflag, struct proc *p)
 1119 {
 1120         struct ksyms_gsymbol *kg = (struct ksyms_gsymbol *)data;
 1121         struct symtab *st;
 1122         Elf_Sym *sym = NULL;
 1123         unsigned long val;
 1124         int error = 0;
 1125         char *str = NULL;
 1126 
 1127         if (cmd == KIOCGVALUE || cmd == KIOCGSYMBOL)
 1128                 str = malloc(ksyms_maxlen, M_DEVBUF, M_WAITOK);
 1129 
 1130         switch (cmd) {
 1131         case KIOCGVALUE:
 1132                 /*
 1133                  * Use the in-kernel symbol lookup code for fast
 1134                  * retreival of a value.
 1135                  */
 1136                 if ((error = copyinstr(kg->kg_name, str, ksyms_maxlen, NULL)))
 1137                         break;
 1138                 if ((error = ksyms_getval_from_userland(NULL, str, &val, KSYMS_EXTERN)))
 1139                         break;
 1140                 error = copyout(&val, kg->kg_value, sizeof(long));
 1141                 break;
 1142 
 1143         case KIOCGSYMBOL:
 1144                 /*
 1145                  * Use the in-kernel symbol lookup code for fast
 1146                  * retreival of a symbol.
 1147                  */
 1148                 if ((error = copyinstr(kg->kg_name, str, ksyms_maxlen, NULL)))
 1149                         break;
 1150                 CIRCLEQ_FOREACH(st, &symtab_queue, sd_queue) {
 1151                         if ((sym = findsym(str, st, 1)) == NULL) /* from userland */
 1152                                 continue;
 1153 
 1154                         /* Skip if bad binding */
 1155                         if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL) {
 1156                                 sym = NULL;
 1157                                 continue;
 1158                         }
 1159                         break;
 1160                 }
 1161                 if (sym != NULL)
 1162                         error = copyout(sym, kg->kg_sym, sizeof(Elf_Sym));
 1163                 else
 1164                         error = ENOENT;
 1165                 break;
 1166 
 1167         case KIOCGSIZE:
 1168                 /*
 1169                  * Get total size of symbol table.
 1170                  */
 1171                 *(int *)data = strsz + symsz + HDRSIZ;
 1172                 break;
 1173 
 1174         default:
 1175                 error = ENOTTY;
 1176                 break;
 1177         }
 1178 
 1179         if (cmd == KIOCGVALUE || cmd == KIOCGSYMBOL)
 1180                 free(str, M_DEVBUF);
 1181 
 1182         return error;
 1183 }
 1184 #endif

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