From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yu-cheng Yu Subject: [PATCH v7 14/14] x86: Discard .note.gnu.property sections Date: Thu, 6 Jun 2019 13:09:26 -0700 Message-ID: <20190606200926.4029-15-yu-cheng.yu@intel.com> References: <20190606200926.4029-1-yu-cheng.yu@intel.com> Return-path: In-Reply-To: <20190606200926.4029-1-yu-cheng.yu@intel.com> Sender: linux-kernel-owner@vger.kernel.org To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit List-Id: linux-api@vger.kernel.org From: "H.J. Lu" With the command-line option, -mx86-used-note=yes, the x86 assembler in binutils 2.32 and above generates a program property note in a note section, .note.gnu.property, to encode used x86 ISAs and features. To exclude .note.gnu.property sections from NOTE segment in x86 kernel linker script: PHDRS { text PT_LOAD FLAGS(5); data PT_LOAD FLAGS(6); percpu PT_LOAD FLAGS(6); init PT_LOAD FLAGS(7); note PT_NOTE FLAGS(0); } SECTIONS { ... .notes : AT(ADDR(.notes) - 0xffffffff80000000) { __start_notes = .; KEEP(*(.not e.*)) __stop_notes = .; } :text :note ... } this patch discards .note.gnu.property sections in kernel linker script by adding /DISCARD/ : { *(.note.gnu.property) } before .notes sections. Since .exit.text and .exit.data sections are discarded at runtime, it undefines EXIT_TEXT and EXIT_DATA to exclude .exit.text and .exit.data sections from default discarded sections. Signed-off-by: H.J. Lu --- arch/x86/kernel/vmlinux.lds.S | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 0850b5149345..d2594b482c09 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -146,6 +146,10 @@ SECTIONS /* End of text section */ _etext = .; + /* .note.gnu.property sections should be discarded */ + /DISCARD/ : { + *(.note.gnu.property) + } NOTES :text :note EXCEPTION_TABLE(16) :text = 0x9090 @@ -382,7 +386,12 @@ SECTIONS STABS_DEBUG DWARF_DEBUG - /* Sections to be discarded */ + /* Sections to be discarded. EXIT_TEXT and EXIT_DATA discard at runtime. + * not link time. */ +#undef EXIT_TEXT +#define EXIT_TEXT +#undef EXIT_DATA +#define EXIT_DATA DISCARDS /DISCARD/ : { *(.eh_frame) -- 2.17.1