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From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	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 <arnd@arndb.de>,
	Andy Lutomirski <luto@amacapital.net>,
	Balbir Singh <bsingharora@gmail.com>,
	Borislav Petkov <bp@alien8.de>,
	Cyrill Gorcunov <gorcunov@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Eugene Syromiatnikov <esyr@redhat.com>,
	Florian Weimer <fweimer@redhat.com>,
	"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Kees Cook <keescook@chromium.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Nadav Amit <nadav.amit@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
	Peter Zijlstra <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
	Dave Martin <Dave.Martin@arm.com>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [PATCH v8 13/14] x86: Discard .note.gnu.property sections
Date: Tue, 13 Aug 2019 13:53:58 -0700
Message-ID: <20190813205359.12196-14-yu-cheng.yu@intel.com> (raw)
In-Reply-To: <20190813205359.12196-1-yu-cheng.yu@intel.com>

From: "H.J. Lu" <hjl.tools@gmail.com>

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 <hjl.tools@gmail.com>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
 arch/x86/kernel/vmlinux.lds.S | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index e2feacf921a0..5ef137493a85 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -146,6 +146,10 @@ SECTIONS
 		_etext = .;
 	} :text = 0x9090
 
+	/* .note.gnu.property sections should be discarded */
+	/DISCARD/ : {
+		*(.note.gnu.property)
+	}
 	NOTES :text :note
 
 	EXCEPTION_TABLE(16) :text = 0x9090
@@ -415,6 +419,12 @@ SECTIONS
 	STABS_DEBUG
 	DWARF_DEBUG
 
+	/* 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



  parent reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-13 20:53 [PATCH v8 00/14] Control-flow Enforcement: Branch Tracking, PTRACE Yu-cheng Yu
2019-08-13 20:53 ` [PATCH v8 01/14] x86/cet/ibt: Add Kconfig option for user-mode Indirect Branch Tracking Yu-cheng Yu
2019-08-13 20:53 ` [PATCH v8 02/14] x86/cet/ibt: User-mode indirect branch tracking support Yu-cheng Yu
2019-08-13 20:53 ` [PATCH v8 03/14] x86/cet/ibt: Handle signals for end branch Yu-cheng Yu
2019-08-13 20:53 ` [PATCH v8 04/14] mm/mmap: Add IBT bitmap size to address space limit check Yu-cheng Yu
2019-08-13 20:53 ` [PATCH v8 05/14] x86/cet/ibt: ELF header parsing for IBT Yu-cheng Yu
2019-08-13 20:53 ` [PATCH v8 06/14] x86/cet/ibt: Add arch_prctl functions " Yu-cheng Yu
2019-08-13 20:53 ` [PATCH v8 07/14] x86/cet/ibt: Add ENDBR to op-code-map Yu-cheng Yu
2019-11-08 13:19   ` Adrian Hunter
2019-08-13 20:53 ` [PATCH v8 08/14] x86/vdso: Insert endbr32/endbr64 to vDSO Yu-cheng Yu
2019-08-13 20:53 ` [PATCH v8 09/14] x86/vdso/32: Add ENDBR32 to __kernel_vsyscall entry point Yu-cheng Yu
2019-08-13 20:53 ` [PATCH v8 10/14] x86/vsyscall/64: Add ENDBR64 to vsyscall entry points Yu-cheng Yu
2019-08-13 20:53 ` [PATCH v8 11/14] x86/vsyscall/64: Fixup shadow stack and branch tracking for vsyscall Yu-cheng Yu
2019-08-13 20:53 ` [PATCH v8 12/14] x86/cet: Add PTRACE interface for CET Yu-cheng Yu
2019-08-13 20:53 ` Yu-cheng Yu [this message]
2019-08-13 20:53 ` [PATCH v8 14/14] Introduce arch_prctl(ARCH_X86_CET_MARK_LEGACY_CODE) Yu-cheng Yu

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