Syminfo Table Section

The syminfo section contains multiple entries of the type Elf32_Syminfo or Elf64_Syminfo. The .SUNW_syminfo section contains one entry for every entry in the associated symbol table (sh_link).

If this section is present in an object, additional symbol information is to be found by taking the symbol index from the associated symbol table and using that to find the corresponding Elf32_Syminfo entry or Elf64_Syminfo entry in this section. The associated symbol table and the Syminfo table will always have the same number of entries.

Index 0 is used to store the current version of the Syminfo table, which is SYMINFO_CURRENT. Since symbol table entry 0 is always reserved for the UNDEF symbol table entry, this usage does not pose any conflicts.

An Syminfo entry has the following format. See sys/link.h.

typedef struct {
        Elf32_Half      si_boundto;
        Elf32_Half      si_flags;
} Elf32_Syminfo;

typedef struct {
        Elf64_Half      si_boundto;
        Elf64_Half      si_flags;
} Elf64_Syminfo;

si_boundto

An index to an entry in the .dynamic section, identified by the sh_info field, which augments the Syminfo flags. For example, a DT_NEEDED entry identifies a dynamic object associated with the Syminfo entry. The entries that follow are reserved values for si_boundto.

Name Value Meaning SYMINFO_BT_SELF 0xffff Symbol bound to self. SYMINFO_BT_PARENT 0xfffe Symbol bound to parent. The parent is the first object to cause this dynamic object to be loaded. SYMINFO_BT_NONE 0xfffd Symbol has no special symbol binding. SYMINFO_BT_EXTERN 0xfffc Symbol definition is external.

si_flags

This bit-field can have flags set, as shown in the following table.

Name Value Meaning SYMINFO_FLG_DIRECT 0x01 Symbol reference has a direct association to the object containing the definition. SYMINFO_FLG_FILTER 0x02 Symbol definition acts as a standard filter. SYMINFO_FLG_COPY 0x04 Symbol definition is the result of a copy-relocation. SYMINFO_FLG_LAZYLOAD 0x08 Symbol reference is to an object that should be lazily loaded. SYMINFO_FLG_DIRECTBIND 0x10 Symbol reference should be bound directly to the definition. SYMINFO_FLG_NOEXTDIRECT 0x20 Do not allow an external reference to directly bind to this symbol definition. SYMINFO_FLG_AUXILIARY 0x40 Symbol definition acts as an auxiliary filter. SYMINFO_FLG_INTERPOSE 0x80 Symbol definition acts as an interposer. This attribute is only applicable for dynamic executables. SYMINFO_FLG_CAP 0x100 Symbol is associated with capabilities. SYMINFO_FLG_DEFERRED 0x200 Symbol should not be included in BIND_NOW relocations.