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| author | Alan Modra <amodra@gmail.com> | 2017-10-03 08:46:39 +1030 |
|---|---|---|
| committer | Alan Modra <amodra@gmail.com> | 2017-10-03 09:36:26 +1030 |
| commit | def5c83c02fcc1c91d3f0da21005e0503b8ec881 (patch) | |
| tree | 62286854efdd097cc76cc52d5931e476ab3405cc /ld/ld.texinfo | |
| parent | 45320ffa0450b27e232d933d2a1c6a09d94ac18b (diff) | |
| download | gdb-def5c83c02fcc1c91d3f0da21005e0503b8ec881.zip gdb-def5c83c02fcc1c91d3f0da21005e0503b8ec881.tar.gz gdb-def5c83c02fcc1c91d3f0da21005e0503b8ec881.tar.bz2 | |
ld -z relro documentation
* ld.texinfo (-z relro): Expand description.
(DATA_SEGMENT_ALIGN): Note that -z relro is not effective when
running with system page size larger than commonpagesize.
(DATA_SEGMENT_RELRO_END): Be explicit about the alignment.
Diffstat (limited to 'ld/ld.texinfo')
| -rw-r--r-- | ld/ld.texinfo | 17 |
1 files changed, 11 insertions, 6 deletions
diff --git a/ld/ld.texinfo b/ld/ld.texinfo index 90a745a..b67a715 100644 --- a/ld/ld.texinfo +++ b/ld/ld.texinfo @@ -1219,7 +1219,10 @@ first called. Marks the object may contain $ORIGIN. @item relro -Create an ELF @code{PT_GNU_RELRO} segment header in the object. +Create an ELF @code{PT_GNU_RELRO} segment header in the object. This +specifies a memory segment that should be made read-only after +relocation, if supported. Specifying @samp{common-page-size} smaller +than the system page size will render this protection ineffective. @item max-page-size=@var{value} Set the emulation maximum page size to @var{value}. @@ -6363,8 +6366,10 @@ bytes in the on-disk file. This expression can only be used directly in @code{SECTIONS} commands, not in any output section descriptions and only once in the linker script. @var{commonpagesize} should be less or equal to @var{maxpagesize} and should -be the system page size the object wants to be optimized for (while still -working on system page sizes up to @var{maxpagesize}). +be the system page size the object wants to be optimized for while still +running on system page sizes up to @var{maxpagesize}. Note however +that @samp{-z relro} protection will not be effective if the system +page size is larger than @var{commonpagesize}. @noindent Example: @@ -6387,9 +6392,9 @@ This defines the end of the @code{PT_GNU_RELRO} segment when @samp{-z relro} option is used. When @samp{-z relro} option is not present, @code{DATA_SEGMENT_RELRO_END} does nothing, otherwise @code{DATA_SEGMENT_ALIGN} is padded so that -@var{exp} + @var{offset} is aligned to the most commonly used page -boundary for particular target. If present in the linker script, -it must always come in between @code{DATA_SEGMENT_ALIGN} and +@var{exp} + @var{offset} is aligned to the @var{commonpagesize} +argument given to @code{DATA_SEGMENT_ALIGN}. If present in the linker +script, it must be placed between @code{DATA_SEGMENT_ALIGN} and @code{DATA_SEGMENT_END}. Evaluates to the second argument plus any padding needed at the end of the @code{PT_GNU_RELRO} segment due to section alignment. |