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

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 1997-2000 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: releng/12.0/sys/sys/linker.h 338211 2018-08-22 20:44:30Z markj $
     */
    
    #ifndef _SYS_LINKER_H_
    #define _SYS_LINKER_H_
    
    #ifdef _KERNEL
    
    #include <machine/elf.h>
    #include <sys/kobj.h>
    
    #ifdef MALLOC_DECLARE
    MALLOC_DECLARE(M_LINKER);
    #endif
    
    struct mod_depend;
    
    /*
     * 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 */
    typedef c_caddr_t c_linker_sym_t;       /* const opaque symbol */
    typedef int (*linker_function_name_callback_t)(const char *, void *);
    
    /*
     * expanded out linker_sym_t
     */
    typedef struct linker_symval {
        const char*         name;
        caddr_t             value;
        size_t              size;
    } linker_symval_t;
    
    typedef int (*linker_function_nameval_callback_t)(linker_file_t, int, linker_symval_t *, void *);
    
    struct common_symbol {
        STAILQ_ENTRY(common_symbol) link;
        char*               name;
        caddr_t             address;
    };
    
    struct linker_file {
        KOBJ_FIELDS;
        int                 refs;           /* reference count */
        int                 userrefs;       /* kldload(2) count */
        int                 flags;
    #define LINKER_FILE_LINKED      0x1     /* file has been fully linked */
    #define LINKER_FILE_MODULES     0x2     /* file has >0 modules at preload */
        TAILQ_ENTRY(linker_file) link;      /* list of all loaded files */
        char*               filename;       /* file which was loaded */
        char*               pathname;       /* file name with full path */
        int                 id;             /* unique id */
        caddr_t             address;        /* load address */
        size_t              size;           /* size of file */
        caddr_t             ctors_addr;     /* address of .ctors */
        size_t              ctors_size;     /* size of .ctors */
        int                 ndeps;          /* number of dependencies */
        linker_file_t*      deps;           /* list of dependencies */
        STAILQ_HEAD(, common_symbol) common; /* list of common symbols */
        TAILQ_HEAD(, module) modules;       /* modules in this file */
        TAILQ_ENTRY(linker_file) loaded;    /* preload dependency support */
        int                 loadcnt;        /* load counter value */
    
        /*
         * Function Boundary Tracing (FBT) or Statically Defined Tracing (SDT)
         * fields.
         */
        int                 nenabled;       /* number of enabled probes. */
        int                 fbt_nentries;   /* number of fbt entries created. */
   };
   
   /*
    * 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 {
       KOBJ_CLASS_FIELDS;
       TAILQ_ENTRY(linker_class) link;     /* list of all file classes */
   };
   
   /*
    * Function type used when iterating over the list of linker files.
    */
   typedef int linker_predicate_t(linker_file_t, void *);
   
   /*
    * The "file" for the kernel.
    */
   extern linker_file_t    linker_kernel_file;
   
   /*
    * Obtain a reference to a module, loading it if required.
    */
   int linker_reference_module(const char* _modname, struct mod_depend *_verinfo,
                               linker_file_t* _result);
   
   /*
    * Release a reference to a module, unloading it if there are no more
    * references.  Note that one should either provide a module name and
    * optional version info or a linker file, but not both.
    */
   int linker_release_module(const char *_modname, struct mod_depend *_verinfo,
                             linker_file_t _file);
   
   /*
    * Iterate over all of the currently loaded linker files calling the
    * predicate function while the function returns 0.  Returns the value
    * returned by the last predicate function.
    */
   int linker_file_foreach(linker_predicate_t *_predicate, void *_context);
   
   /*
    * Lookup a symbol in a file.  If deps is TRUE, look in dependencies
    * if not found in file.
    */
   caddr_t linker_file_lookup_symbol(linker_file_t _file, const char* _name,
                                     int _deps);
   
   /*
    * Lookup a linker set in a file.  Return pointers to the first entry,
    * last + 1, and count of entries.  Use: for (p = start; p < stop; p++) {}
    * void *start is really: "struct yoursetmember ***start;"
    */
   int linker_file_lookup_set(linker_file_t _file, const char *_name,
                              void *_start, void *_stop, int *_count);
   
   /*
    * List all functions in a file.
    */
   int linker_file_function_listall(linker_file_t,
                                    linker_function_nameval_callback_t, void *);
   
   /*
    * Functions solely for use by the linker class handlers.
    */
   int linker_add_class(linker_class_t _cls);
   int linker_file_unload(linker_file_t _file, int flags);
   int linker_load_dependencies(linker_file_t _lf);
   linker_file_t linker_make_file(const char* _filename, linker_class_t _cls);
   
   /*
    * DDB Helpers, tuned specifically for ddb/db_kld.c
    */
   int linker_ddb_lookup(const char *_symstr, c_linker_sym_t *_sym);
   int linker_ddb_search_symbol(caddr_t _value, c_linker_sym_t *_sym,
                                long *_diffp);
   int linker_ddb_symbol_values(c_linker_sym_t _sym, linker_symval_t *_symval);
   int linker_ddb_search_symbol_name(caddr_t value, char *buf, u_int buflen,
                                     long *offset);
   
   /*
    * stack(9) helper for situations where kernel locking is required.
    */
   int linker_search_symbol_name(caddr_t value, char *buf, u_int buflen,
       long *offset);
   
   
   /* HWPMC helper */
   void *linker_hwpmc_list_objects(void);
   
   #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_ARGS            0x0006          /* Parameters string */
   #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 */
   /* These values are MD on these two platforms */
   #if !defined(__sparc64__) && !defined(__powerpc__)
   #define MODINFOMD_ENVP          0x0006          /* envp[] */
   #define MODINFOMD_HOWTO         0x0007          /* boothowto */
   #define MODINFOMD_KERNEND       0x0008          /* kernend */
   #endif
   #define MODINFOMD_SHDR          0x0009          /* section header table */
   #define MODINFOMD_CTORS_ADDR    0x000a          /* address of .ctors */
   #define MODINFOMD_CTORS_SIZE    0x000b          /* size of .ctors */
   #define MODINFOMD_FW_HANDLE     0x000c          /* Firmware dependent handle */
   #define MODINFOMD_KEYBUF        0x000d          /* Crypto key intake buffer */
   #define MODINFOMD_NOCOPY        0x8000          /* don't copy this metadata to the kernel */
   
   #define MODINFOMD_DEPLIST       (0x4001 | MODINFOMD_NOCOPY)     /* depends on */
   
   #ifdef _KERNEL
   #define MD_FETCH(mdp, info, type) ({ \
           type *__p; \
           __p = (type *)preload_search_info((mdp), MODINFO_METADATA | (info)); \
           __p ? *__p : 0; \
   })
   #endif
   
   #define LINKER_HINTS_VERSION    1               /* linker.hints file version */
   #define LINKER_HINTS_MAX        (1 << 20)       /* Allow at most 1MB for linker.hints */
   
   #ifdef _KERNEL
   
   /*
    * Module lookup
    */
   extern vm_offset_t      preload_addr_relocate;
   extern caddr_t          preload_metadata;
   
   extern void *           preload_fetch_addr(caddr_t _mod);
   extern size_t           preload_fetch_size(caddr_t _mod);
   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
   
   typedef int elf_lookup_fn(linker_file_t, Elf_Size, int, Elf_Addr *);
   
   /* Support functions */
   bool    elf_is_ifunc_reloc(Elf_Size r_info);
   int     elf_reloc(linker_file_t _lf, Elf_Addr base, const void *_rel,
               int _type, elf_lookup_fn _lu);
   int     elf_reloc_local(linker_file_t _lf, Elf_Addr base, const void *_rel,
               int _type, elf_lookup_fn _lu);
   Elf_Addr elf_relocaddr(linker_file_t _lf, Elf_Addr addr);
   const Elf_Sym *elf_get_sym(linker_file_t _lf, Elf_Size _symidx);
   const char *elf_get_symname(linker_file_t _lf, Elf_Size _symidx);
   void    link_elf_ireloc(caddr_t kmdp);
   
   typedef struct linker_ctf {
           const uint8_t   *ctftab;        /* Decompressed CTF data. */
           int             ctfcnt;         /* Number of CTF data bytes. */
           const Elf_Sym   *symtab;        /* Ptr to the symbol table. */
           int             nsym;           /* Number of symbols. */
           const char      *strtab;        /* Ptr to the string table. */
           int             strcnt;         /* Number of string bytes. */
           uint32_t        **ctfoffp;      /* Ptr to array of obj/fnc offsets. */
           uint32_t        **typoffp;      /* Ptr to array of type offsets. */
           long            *typlenp;       /* Ptr to number of type data entries. */
   } linker_ctf_t;
   
   int     linker_ctf_get(linker_file_t, linker_ctf_t *);
   
   int elf_cpu_load_file(linker_file_t);
   int elf_cpu_unload_file(linker_file_t);
   
   /* values for type */
   #define ELF_RELOC_REL   1
   #define ELF_RELOC_RELA  2
   
   /*
    * This is version 1 of the KLD file status structure. It is identified
    * by its _size_ in the version field.
    */
   struct kld_file_stat_1 {
       int         version;        /* set to sizeof(struct kld_file_stat_1) */
       char        name[MAXPATHLEN];
       int         refs;
       int         id;
       caddr_t     address;        /* load address */
       size_t      size;           /* size in bytes */
   };
   #endif /* _KERNEL */
   
   struct kld_file_stat {
       int         version;        /* set to sizeof(struct kld_file_stat) */
       char        name[MAXPATHLEN];
       int         refs;
       int         id;
       caddr_t     address;        /* load address */
       size_t      size;           /* size in bytes */
       char        pathname[MAXPATHLEN];
   };
   
   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
   
   /*
    * Flags for kldunloadf() and linker_file_unload()
    */
   #define LINKER_UNLOAD_NORMAL    0
   #define LINKER_UNLOAD_FORCE     1
   
   #ifndef _KERNEL
   
   #include <sys/cdefs.h>
   
   __BEGIN_DECLS
   int     kldload(const char* _file);
   int     kldunload(int _fileid);
   int     kldunloadf(int _fileid, int flags);
   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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