From 8ee10e86093150c70360d9e26b29e6d9b6398f33 Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Mon, 1 Mar 2021 08:22:49 +1030 Subject: PR27451, -z start_stop_gc When --gc-sections is in effect, a reference from a retained section to __start_SECNAME or __stop_SECNAME causes all input sections named SECNAME to also be retained, if SECNAME is representable as a C identifier and either __start_SECNAME or __stop_SECNAME is synthesized by the linker. Add an option to disable that feature, effectively ignoring any relocation that references a synthesized linker defined __start_ or __stop_ symbol. PR 27451 include/ * bfdlink.h (struct bfd_link_info): Add start_stop_gc. bfd/ * elflink.c (_bfd_elf_gc_mark_rsec): Ignore synthesized linker defined start/stop symbols when start_stop_gc. (bfd_elf_gc_mark_dynamic_ref_symbol): Likewise. (bfd_elf_define_start_stop): Don't modify ldscript_def syms. * linker.c (bfd_generic_define_start_stop): Likewise. ld/ * emultempl/elf.em: Handle -z start-stop-gc and -z nostart-stop-gc. * lexsup.c (elf_static_list_options): Display help for them. Move help for -z stack-size to here from elf_shlib_list_options. Add help for -z start-stop-visibility and -z undefs. * ld.texi: Document -z start-stop-gc and -z nostart-stop-gc. * NEWS: Mention -z start-stop-gc. * testsuite/ld-gc/start2.s, * testsuite/ld-gc/start2.d: New test. * testsuite/ld-gc/gc.exp: Run it. --- ld/ld.texi | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'ld/ld.texi') diff --git a/ld/ld.texi b/ld/ld.texi index 9643818..6d016ec 100644 --- a/ld/ld.texi +++ b/ld/ld.texi @@ -1453,6 +1453,23 @@ Specify a stack size for an ELF @code{PT_GNU_STACK} segment. Specifying zero will override any default non-zero sized @code{PT_GNU_STACK} segment creation. +@item start-stop-gc +@itemx nostart-stop-gc +@cindex start-stop-gc +When @samp{--gc-sections} is in effect, a reference from a retained +section to @code{__start_SECNAME} or @code{__stop_SECNAME} causes all +input sections named @code{SECNAME} to also be retained, if +@code{SECNAME} is representable as a C identifier and either +@code{__start_SECNAME} or @code{__stop_SECNAME} is synthesized by the +linker. @samp{-z start-stop-gc} disables this effect, allowing +sections to be garbage collected as if the special synthesized symbols +were not defined. @samp{-z start-stop-gc} has no effect on a +definition of @code{__start_SECNAME} or @code{__stop_SECNAME} in an +object file or linker script. Such a definition will prevent the +linker providing a synthesized @code{__start_SECNAME} or +@code{__stop_SECNAME} respectively, and therefore the special +treatment by garbage collection for those references. + @item start-stop-visibility=@var{value} @cindex visibility @cindex ELF symbol visibility -- cgit v1.1