diff options
Diffstat (limited to 'ld/ld.texi')
| -rw-r--r-- | ld/ld.texi | 75 |
1 files changed, 56 insertions, 19 deletions
@@ -2784,28 +2784,51 @@ detect the use of global constructors. @cindex warnings, on executable stack @cindex executable stack, warnings on @item --warn-execstack +@itemx --warn-execstack-objects @itemx --no-warn-execstack -On ELF platforms this option controls how the linker generates warning -messages when it creates an output file with an executable stack. By -default the linker will not warn if the @command{-z execstack} command -line option has been used, but this behaviour can be overridden by the -@option{--warn-execstack} option. - -On the other hand the linker will normally warn if the stack is made -executable because one or more of the input files need an execuable -stack and neither of the @command{-z execstack} or @command{-z -noexecstack} command line options have been specified. This warning -can be disabled via the @command{--no-warn-execstack} option. - -Note: ELF format input files specify that they need an executable +On ELF platforms the linker may generate warning messages if it is +asked to create an output file that contains an executable stack. +There are three possible states: +@enumerate +@item +Do not generate any warnings. +@item +Always generate warnings, even if the executable stack is requested +via the @option{-z execstack} command line option. +@item +Only generate a warning if an object file requests an executable +stack, but not if the @option{-z execstack} option is used. +@end enumerate + +The default state depends upon how the linker was configured when it +was built. The @option{--no-warn-execstack} option always puts the +linker into the no-warnings state. The @option{--warn-execstack} +option puts the linker into the warn-always state. The +@option{--warn-execstack-objects} option puts the linker into the +warn-for-object-files-only state. + +Note: ELF format input files can specify that they need an executable stack by having a @var{.note.GNU-stack} section with the executable bit set in its section flags. They can specify that they do not need -an executable stack by having that section, but without the executable -flag bit set. If an input file does not have a @var{.note.GNU-stack} -section present then the default behaviour is target specific. For -some targets, then absence of such a section implies that an -executable stack @emph{is} required. This is often a problem for hand -crafted assembler files. +an executable stack by having the same section, but without the +executable flag bit set. If an input file does not have a +@var{.note.GNU-stack} section then the default behaviour is target +specific. For some targets, then absence of such a section implies +that an executable stack @emph{is} required. This is often a problem +for hand crafted assembler files. + +@kindex --error-execstack +@item --error-execstack +@itemx --no-error-execstack +If the linker is going to generate a warning message about an +executable stack then the @option{--error-execstack} option will +instead change that warning into an error. Note - this option does +not change the linker's execstack warning generation state. Use +@option{--warn-execstack} or @option{--warn-execstack-objects} to set +a specific warning state. + +The @option{--no-error-execstack} option will restore the default +behaviour of generating warning messages. @kindex --warn-multiple-gp @item --warn-multiple-gp @@ -2844,6 +2867,20 @@ These warnings are enabled by default. They can be disabled via the @option{--no-warn-rwx-segments} option and re-enabled via the @option{--warn-rwx-segments} option. +@kindex --error-rwx-segments +@item --error-rwx-segments +@itemx --no-error-rwx-segments +If the linker is going to generate a warning message about an +executable, writeable segment, or an executable TLS segment, then the +@option{--error-rwx-segments} option will turn this warning into an +error instead. The @option{--no-error-rwx-segments} option will +restore the default behaviour of just generating a warning message. + +Note - the @option{--error-rwx-segments} option does not by itself +turn on warnings about these segments. These warnings are either +enabled by default, if the linker was configured that way, or via the +@option{--warn-rwx-segments} command line option. + @kindex --warn-section-align @cindex warnings, on section alignment @cindex section alignment, warnings on |