From bbce18b8d1f572012c40e77c9d0a6dfd28cd25f3 Mon Sep 17 00:00:00 2001
From: Ed Maste <emaste@FreeBSD.org>
Date: Tue, 20 Nov 2018 20:59:49 +0000
Subject: [PATCH] Add NT_FREEBSD_FEATURE_CTL ELF note to csu

This note will be used to allow binaries to opt out of, or in to,
upcoming vulnerability mitigation and other features.  It is not yet
connected but being added now to facilitate testing and ensure
compatibility with existing kernels and tools.

Reviewed by:	brooks, jhb, kib, markj
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D17438
---
 lib/csu/common/crtbrand.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/lib/csu/common/crtbrand.c b/lib/csu/common/crtbrand.c
index c407de435b96..f8fb0024db24 100644
--- a/lib/csu/common/crtbrand.c
+++ b/lib/csu/common/crtbrand.c
@@ -67,3 +67,18 @@ static const struct {
 	.name = NOTE_FREEBSD_VENDOR,
 	.desc = __FreeBSD_version
 };
+
+static const struct {
+	int32_t	namesz;
+	int32_t	descsz;
+	int32_t	type;
+	char	name[sizeof(NOTE_FREEBSD_VENDOR)];
+	uint32_t	desc[1];
+} crt_feature_ctl __attribute__ ((section (NOTE_SECTION),
+    aligned(4))) __used = {
+	.namesz = sizeof(NOTE_FREEBSD_VENDOR),
+	.descsz = sizeof(uint32_t),
+	.type = NT_FREEBSD_FEATURE_CTL,
+	.name = NOTE_FREEBSD_VENDOR,
+	.desc = { 0 }
+};