From: Josh Poimboeuf <jpoimboe@redhat.com> To: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Anvin <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Jessica Yu <jeyu@redhat.com> Subject: [PATCH v2] objtool, module: discard objtool annotation sections for modules Date: Wed, 1 Mar 2017 12:04:44 -0600 Message-ID: <20170301180444.lhd53c5tibc4ns77@treble> (raw) In-Reply-To: <CA+55aFxLpj2x+VP5DE-N+x6stfMtfZ7ayzCnZhwyuVSEgmj5-w@mail.gmail.com> The '__unreachable' and '__func_stack_frame_non_standard' sections are only used at compile time. They're discarded for vmlinux but they should also be discarded for modules. Since this is a recurring pattern, prefix the section names with ".discard.". It's a nice convention and vmlinux.lds.h already discards such sections. Also remove the 'a' (allocatable) flag from the __unreachable section since it doesn't make sense for a discarded section. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Fixes: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends") Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> --- arch/x86/kernel/vmlinux.lds.S | 2 -- include/linux/compiler-gcc.h | 2 +- include/linux/frame.h | 2 +- scripts/mod/modpost.c | 1 + scripts/module-common.lds | 5 ++++- tools/objtool/builtin-check.c | 7 ++++--- 6 files changed, 11 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index ad0118f..c74ae9c 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -345,8 +345,6 @@ SECTIONS DISCARDS /DISCARD/ : { *(.eh_frame) - *(__func_stack_frame_non_standard) - *(__unreachable) } } diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index b6bb901..0efef9c 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -200,7 +200,7 @@ #ifdef CONFIG_STACK_VALIDATION #define annotate_unreachable() ({ \ asm("%c0:\t\n" \ - ".pushsection __unreachable, \"a\"\t\n" \ + ".pushsection .discard.unreachable\t\n" \ ".long %c0b - .\t\n" \ ".popsection\t\n" : : "i" (__LINE__)); \ }) diff --git a/include/linux/frame.h b/include/linux/frame.h index e6baaba..d772c61 100644 --- a/include/linux/frame.h +++ b/include/linux/frame.h @@ -11,7 +11,7 @@ * For more information, see tools/objtool/Documentation/stack-validation.txt. */ #define STACK_FRAME_NON_STANDARD(func) \ - static void __used __section(__func_stack_frame_non_standard) \ + static void __used __section(.discard.func_stack_frame_non_standard) \ *__func_stack_frame_non_standard_##func = func #else /* !CONFIG_STACK_VALIDATION */ diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 4dedd0d..30d752a 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -854,6 +854,7 @@ static const char *const section_white_list[] = ".cmem*", /* EZchip */ ".fmt_slot*", /* EZchip */ ".gnu.lto*", + ".discard.*", NULL }; diff --git a/scripts/module-common.lds b/scripts/module-common.lds index 73a2c7d..cf7e52e 100644 --- a/scripts/module-common.lds +++ b/scripts/module-common.lds @@ -4,7 +4,10 @@ * combine them automatically. */ SECTIONS { - /DISCARD/ : { *(.discard) } + /DISCARD/ : { + *(.discard) + *(.discard.*) + } __ksymtab 0 : { *(SORT(___ksymtab+*)) } __ksymtab_gpl 0 : { *(SORT(___ksymtab_gpl+*)) } diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c index 5fc52ee..bd12eb1 100644 --- a/tools/objtool/builtin-check.c +++ b/tools/objtool/builtin-check.c @@ -339,13 +339,14 @@ static int add_dead_ends(struct objtool_file *file) struct instruction *insn; bool found; - sec = find_section_by_name(file->elf, ".rela__unreachable"); + sec = find_section_by_name(file->elf, ".rela.discard.unreachable"); if (!sec) return 0; list_for_each_entry(rela, &sec->rela_list, list) { if (rela->sym->type != STT_SECTION) { - WARN("unexpected relocation symbol type in .rela__unreachable"); + WARN("unexpected relocation symbol type in %s", + sec->name); return -1; } insn = find_insn(file, rela->sym->sec, rela->addend); @@ -1272,7 +1273,7 @@ int cmd_check(int argc, const char **argv) INIT_LIST_HEAD(&file.insn_list); hash_init(file.insn_hash); - file.whitelist = find_section_by_name(file.elf, "__func_stack_frame_non_standard"); + file.whitelist = find_section_by_name(file.elf, ".discard.func_stack_frame_non_standard"); file.rodata = find_section_by_name(file.elf, ".rodata"); file.ignore_unreachables = false; file.c_file = find_section_by_name(file.elf, ".comment"); -- 2.7.4
next prev parent reply index Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-03-01 15:20 [PATCH] objtool, module: discard __unreachable section " Josh Poimboeuf 2017-03-01 16:44 ` hpa 2017-03-01 17:01 ` Linus Torvalds 2017-03-01 17:22 ` hpa 2017-03-01 18:04 ` Josh Poimboeuf [this message] 2017-03-01 19:37 ` [tip:core/urgent] objtool, modules: Discard objtool annotation sections " tip-bot for Josh Poimboeuf
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