FreeBSD/Linux Kernel Cross Reference
sys/sys/linker.h

     /*-
      * Copyright (c) 1997 Doug Rabson
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
     *
     * $FreeBSD$
     */
    
    #ifndef _SYS_LINKER_H_
    #define _SYS_LINKER_H_
    
    #ifdef KERNEL
    
    #include <machine/elf.h>
    
    #ifdef MALLOC_DECLARE
    MALLOC_DECLARE(M_LINKER);
    #endif
    
    /*
     * Object representing a file which has been loaded by the linker.
     */
    typedef struct linker_file* linker_file_t;
    typedef TAILQ_HEAD(, linker_file) linker_file_list_t;
    
    typedef caddr_t linker_sym_t;   /* opaque symbol */
    
    /*
     * expanded out linker_sym_t
     */
    typedef struct linker_symval {
        const char*         name;
        caddr_t             value;
        size_t              size;
    } linker_symval_t;
    
    struct linker_file_ops {
        /*
         * Lookup a symbol in the file's symbol table.  If the symbol is
         * not found then return ENOENT, otherwise zero.  If the symbol
         * found is a common symbol, return with *address set to zero and
         * *size set to the size of the common space required.  Otherwise
         * set *address the value of the symbol.
         */
        int                 (*lookup_symbol)(linker_file_t, const char* name,
                                             linker_sym_t* sym);
    
        int                 (*symbol_values)(linker_file_t, linker_sym_t,
                                             linker_symval_t*);
    
        int                 (*search_symbol)(linker_file_t, caddr_t value,
                                             linker_sym_t* sym, long* diffp);
    
        /*
         * Unload a file, releasing dependancies and freeing storage.
         */
        void                (*unload)(linker_file_t);
    };
    
    struct common_symbol {
        STAILQ_ENTRY(common_symbol) link;
        char*               name;
        caddr_t             address;
    };
    
    struct linker_file {
        int                 refs;           /* reference count */
        int                 userrefs;       /* kldload(2) count */
        int                 flags;
    #define LINKER_FILE_LINKED      0x1     /* file has been fully linked */
        TAILQ_ENTRY(linker_file) link;      /* list of all loaded files */
        char*               filename;       /* file which was loaded */
        int                 id;             /* unique id */
        caddr_t             address;        /* load address */
        size_t              size;           /* size of file */
        int                 ndeps;          /* number of dependancies */
        linker_file_t*      deps;           /* list of dependancies */
        STAILQ_HEAD(, common_symbol) common; /* list of common symbols */
        TAILQ_HEAD(, module) modules;       /* modules in this file */
       void*               priv;           /* implementation data */
   
       struct linker_file_ops* ops;
   };
   
   /*
    * Object implementing a class of file (a.out, elf, etc.)
    */
   typedef struct linker_class *linker_class_t;
   typedef TAILQ_HEAD(, linker_class) linker_class_list_t;
   
   struct linker_class_ops {
       /* 
        * Load a file, returning the new linker_file_t in *result.  If
        * the class does not recognise the file type, zero should be
        * returned, without modifying *result.  If the file is
        * recognised, the file should be loaded, *result set to the new
        * file and zero returned.  If some other error is detected an
        * appropriate errno should be returned.
        */
       int         (*load_file)(const char* filename, linker_file_t* result);
   };
   
   struct linker_class {
       TAILQ_ENTRY(linker_class) link;     /* list of all file classes */
       const char*         desc;           /* description (e.g. "a.out") */
       void*               priv;           /* implementation data */
   
       struct linker_class_ops *ops;
   };
   
   /*
    * The file which is currently loading.  Used to register modules with
    * the files which contain them.
    */
   extern linker_file_t    linker_current_file;
   
   /*
    * The "file" for the kernel.
    */
   extern linker_file_t    linker_kernel_file;
   
   /*
    * Add a new file class to the linker.
    */
   int linker_add_class(const char* desc, void* priv,
                        struct linker_class_ops* ops);
   
   /*
    * Load a file, trying each file class until one succeeds.
    */
   int linker_load_file(const char* filename, linker_file_t* result);
   
   /*
    * Find a currently loaded file given its filename.
    */
   linker_file_t linker_find_file_by_name(const char* filename);
   
   /*
    * Find a currently loaded file given its file id.
    */
   linker_file_t linker_find_file_by_id(int fileid);
   
   /*
    * Called from a class handler when a file is laoded.
    */
   linker_file_t linker_make_file(const char* filename, void* priv,
                                  struct linker_file_ops* ops);
   
   /*
    * Unload a file, freeing up memory.
    */
   int linker_file_unload(linker_file_t file);
   
   /*
    * Add a dependancy to a file.
    */
   int linker_file_add_dependancy(linker_file_t file, linker_file_t dep);
   
   /*
    * Lookup a symbol in a file.  If deps is TRUE, look in dependancies
    * if not found in file.
    */
   caddr_t linker_file_lookup_symbol(linker_file_t file, const char* name, 
                                     int deps);
   
   /*
    * Search the linker path for the module.  Return the full pathname in
    * a malloc'ed buffer.
    */
   char *linker_search_path(const char *filename);
   
   /*
    * DDB Helpers, tuned specifically for ddb/db_kld.c
    */
   int linker_ddb_lookup(char *symstr, linker_sym_t *sym);
   int linker_ddb_search_symbol(caddr_t value, linker_sym_t *sym, long *diffp);
   int linker_ddb_symbol_values(linker_sym_t sym, linker_symval_t *symval);
   
   
   #endif  /* KERNEL */
   
   /*
    * Module information subtypes
    */
   #define MODINFO_END             0x0000          /* End of list */
   #define MODINFO_NAME            0x0001          /* Name of module (string) */
   #define MODINFO_TYPE            0x0002          /* Type of module (string) */
   #define MODINFO_ADDR            0x0003          /* Loaded address */
   #define MODINFO_SIZE            0x0004          /* Size of module */
   #define MODINFO_EMPTY           0x0005          /* Has been deleted */
   #define MODINFO_METADATA        0x8000          /* Module-specfic */
   
   #define MODINFOMD_AOUTEXEC      0x0001          /* a.out exec header */
   #define MODINFOMD_ELFHDR        0x0002          /* ELF header */
   #define MODINFOMD_SSYM          0x0003          /* start of symbols */
   #define MODINFOMD_ESYM          0x0004          /* end of symbols */
   #define MODINFOMD_DYNAMIC       0x0005          /* _DYNAMIC pointer */
   #define MODINFOMD_NOCOPY        0x8000          /* don't copy this metadata to the kernel */
   
   #define MODINFOMD_DEPLIST       (0x4001 | MODINFOMD_NOCOPY)     /* depends on */
   
   #ifdef KERNEL
   
   /*
    * Module lookup
    */
   extern caddr_t          preload_metadata;
   extern caddr_t          preload_search_by_name(const char *name);
   extern caddr_t          preload_search_by_type(const char *type);
   extern caddr_t          preload_search_next_name(caddr_t base);
   extern caddr_t          preload_search_info(caddr_t mod, int inf);
   extern void             preload_delete_name(const char *name);
   extern void             preload_bootstrap_relocate(vm_offset_t offset);
   
   #ifdef KLD_DEBUG
   
   extern int kld_debug;
   #define KLD_DEBUG_FILE  1       /* file load/unload */
   #define KLD_DEBUG_SYM   2       /* symbol lookup */
   
   #define KLD_DPF(cat, args)                                      \
           do {                                                    \
                   if (kld_debug & KLD_DEBUG_##cat) printf args;   \
           } while (0)
   
   #else
   
   #define KLD_DPF(cat, args)
   
   #endif
   
   /* Support functions */
   int     elf_reloc(linker_file_t lf, const void *rel, int type, const char *sym);
   /* values for type */
   #define ELF_RELOC_REL   1
   #define ELF_RELOC_RELA  2
   
   #endif /* KERNEL */
   
   struct kld_file_stat {
       int         version;        /* set to sizeof(linker_file_stat) */
       char        name[MAXPATHLEN];
       int         refs;
       int         id;
       caddr_t     address;        /* load address */
       size_t      size;           /* size in bytes */
   };
   
   struct kld_sym_lookup {
       int         version;        /* set to sizeof(struct kld_sym_lookup) */
       char        *symname;       /* Symbol name we are looking up */
       u_long      symvalue;
       size_t      symsize;
   };
   #define KLDSYM_LOOKUP   1
   
   #ifndef KERNEL
   
   #include <sys/cdefs.h>
   
   __BEGIN_DECLS
   int     kldload(const char* file);
   int     kldunload(int fileid);
   int     kldfind(const char* file);
   int     kldnext(int fileid);
   int     kldstat(int fileid, struct kld_file_stat* stat);
   int     kldfirstmod(int fileid);
   int     kldsym(int _fileid, int _cmd, void *_data);
   __END_DECLS
   
   #endif
   
   #endif /* !_SYS_LINKER_H_ */

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