From 702d167134149f420ea3bcbc194d63a2653a0c27 Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Sat, 14 Apr 2018 16:23:56 +0930 Subject: powerpc common-page-size max-page-size only matters for demand paged executables or shared libraries, and the ideal size is the largest value used by your operating system. Values larger than necessary just waste file space and memory. common-page-size also affects file and memory size, trading a possible small increase in file size for a decrease in memory size when the operating system is using a common-page-size page. With a powerpc max-page-size of 64k and common-page-size of 4k many executables will use no more memory pages when the system page size is 4k than an executable linked with -z max-page-size=0x1000, yet will still run on a system using 64k pages. However, when running on a system using 64k pages relro protection will not be completely effective. Due to the relro problem, powerpc binutils has been using a default common-page-size of 64k since 2014-12-18 (git commit 04c6a44c7), leading to complaints about increased file and memory sizes. People not using relro do have a valid reason to complain.. So this patch introduces an extra back-end value to use as the default for common-page-size when generating relro executables, and enables the support for powerpc. Non relro executables will now be generated with a default common-page-size of 4k. bfd/ * elf-bfd.h (struct elf_backend_data): Add relropagesize. * elfxx-target.h (ELF_RELROPAGESIZE): Provide default and sanity test. (elfNN_bed): Init relropagesize. * bfd.c (bfd_emul_get_commonpagesize): Add boolean param to select relropagesize. * elf32-ppc.c (ELF_COMMONPAGESIZE): Define as 0x1000. (ELF_RELROPAGESIZE): Define as ELF_MAXPAGESIZE. (ELF_MINPAGESIZE): Don't define. * elf64-ppc.c (ELF_COMMONPAGESIZE): Define as 0x1000. (ELF_RELROPAGESIZE): Define as ELF_MAXPAGESIZE. * bfd-in2.h: Regenerate. ld/ * ldmain.c (main): Move config.maxpagesize and config.commonpagesize initialization to.. * ldemul.c (after_parse_default): ..here. * testsuite/ld-powerpc/ppc476-shared.d: Pass -z common-page-size. * testsuite/ld-powerpc/ppc476-shared2.d: Likewise. --- bfd/elfxx-target.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'bfd/elfxx-target.h') diff --git a/bfd/elfxx-target.h b/bfd/elfxx-target.h index ccab02d..89efed3 100644 --- a/bfd/elfxx-target.h +++ b/bfd/elfxx-target.h @@ -367,6 +367,10 @@ #define ELF_COMMONPAGESIZE ELF_MAXPAGESIZE #endif +#ifndef ELF_RELROPAGESIZE +#define ELF_RELROPAGESIZE ELF_COMMONPAGESIZE +#endif + #ifndef ELF_MINPAGESIZE #define ELF_MINPAGESIZE ELF_COMMONPAGESIZE #endif @@ -374,9 +378,15 @@ #if ELF_COMMONPAGESIZE > ELF_MAXPAGESIZE # error ELF_COMMONPAGESIZE > ELF_MAXPAGESIZE #endif +#if ELF_RELROPAGESIZE > ELF_MAXPAGESIZE +# error ELF_RELROPAGESIZE > ELF_MAXPAGESIZE +#endif #if ELF_MINPAGESIZE > ELF_COMMONPAGESIZE # error ELF_MINPAGESIZE > ELF_COMMONPAGESIZE #endif +#if ELF_MINPAGESIZE > ELF_RELROPAGESIZE +# error ELF_MINPAGESIZE > ELF_RELROPAGESIZE +#endif #ifndef ELF_DYNAMIC_SEC_FLAGS /* Note that we set the SEC_IN_MEMORY flag for these sections. */ @@ -757,6 +767,7 @@ static struct elf_backend_data elfNN_bed = ELF_MAXPAGESIZE, /* maxpagesize */ ELF_MINPAGESIZE, /* minpagesize */ ELF_COMMONPAGESIZE, /* commonpagesize */ + ELF_RELROPAGESIZE, /* commonpagesize to use with -z relro */ ELF_DYNAMIC_SEC_FLAGS, /* dynamic_sec_flags */ elf_backend_arch_data, elf_info_to_howto, -- cgit v1.1