Document:

- new p_flag: PT_GNU_STACK
- new sections: .gnu.version .gnu.version_d .gnu.version_r
  .note.GNU-stack
- new structures: ElfN_Verdef ElfN_Verdaux ElfN_Verneed ElfN_Vernaux

man5/elf.5

@@ -27,8 +27,9 @@
 .\"
 .\" Slightly adapted - aeb, 2004-01-01
 .\" 2005-07-15, Mike Frysinger <vapier@gentoo.org>, various fixes
+.\" 2007-10-11, Mike Frysinger <vapier@gentoo.org>, various fixes
 .\"
-.Dd July 31, 1999
+.Dd October 11, 2007
 .Dt ELF 5
 .Os
 .Sh NAME
@@ -585,6 +586,11 @@ are reserved for processor-specific semantics.
 Values less than or equal to
 .Sy PT_LOPROC
 are reserved for processor-specific semantics.
+.It PT_GNU_STACK
+GNU extension which is used by the Linux kernel to control the state of the
+stack via the flags set in the 
+.Sy p_flags
+member.
 .El
 .Pp
 .It Dv p_offset
@@ -607,7 +613,7 @@ It may be zero.
 This member holds the number of bytes in the memory image of the segment.
 It may be zero.
 .It Dv p_flags
-This member holds flags relevant to the segment:
+This member holds a bitmask of flags relevant to the segment:
 .Pp
 .Bl -tag -width "PF_X" -compact
 .It Dv PF_X
@@ -999,6 +1005,25 @@ The attributes used are
 .Sy SHF_ALLOC
 and
 .Sy SHF_EXECINSTR .
+.It .gnu.version
+This section holds the version symbol table, an array of ElfN_Half elements.
+This section is of type
+.Sy SHT_GNU_versym .
+The attribute type used is
+.Sy SHF_ALLOC .
+.It .gnu.version_d
+This section holds the version symbol definitons, a table of ElfN_Verdef
+structures.  This section is of type
+.Sy SHT_GNU_verdef .
+The attribute type used is
+.Sy SHF_ALLOC .
+.It .gnu.version_r
+This section holds the version symbol needed elements, a table of
+ElfN_Verneed structures.  This section is of
+type
+.Sy SHT_GNU_versym .
+The attribute type used is
+.Sy SHF_ALLOC .
 .It .got
 This section holds the global offset table.
 This section is of type
@@ -1050,6 +1075,14 @@ native executables usually contain a
 .Sy .note.openbsd.ident
 section to identify themselves, for the kernel to bypass any compatibility
 ELF binary emulation tests when loading the file.
+.It .note.GNU-stack
+This section is used in Linux object files for declaring stack attributes.
+This section is of type
+.Sy SHT_PROGBITS .
+The only attribute used is
+.Sy SHF_EXECINSTR .
+This indicates to the GNU linker that the object file requires an
+executable stack.
 .It .plt
 This section holds the procedure linkage table.
 This section is of type
@@ -1273,7 +1306,23 @@ convert a binding and a type into an st_info value.
 .El
 .Pp
 .It Dv st_other
-This member currently holds zero and has no defined meaning.
+This member defines the symbol visibility.
+.Bl -tag -width "STV_PROTECTED"
+.It Dv STV_DEFAULT
+Default symbol visibility rules.
+.It Dv STV_INTERNAL
+Processor specific hidden class.
+.It Dv STV_HIDDEN
+Symbol is unavailable in other modules.
+.It Dv STV_PROTECTED
+Not preemptible, not exported.
+.Pp
+There are macros for extracting the visibility type:
+.Pp
+.Fn ELF32_ST_VISIBILITY other
+or
+.Fn ELF64_ST_VISIBILITY other
+.El
 .It Dv st_shndx
 Every symbol table entry is
 .Dq defined