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From:   Josh Poimboeuf <jpoimboe@redhat.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        Miroslav Benes <mbenes@suse.cz>
Subject: [PATCH] objtool: Add CONFIG_HAVE_UACCESS_VALIDATION
Date:   Tue, 19 Apr 2022 09:05:09 -0700
Message-Id: <d393d5e2fe73aec6e8e41d5c24f4b6fe8583f2d8.1650384225.git.jpoimboe@redhat.com>
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Allow an arch specify that it has objtool uaccess validation with
CONFIG_HAVE_UACCESS_VALIDATION.  For now, doing so unconditionally
selects CONFIG_OBJTOOL.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 arch/Kconfig            | 4 ++++
 arch/x86/Kconfig        | 1 +
 scripts/Makefile.build  | 2 +-
 scripts/link-vmlinux.sh | 4 +++-
 4 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 1e19da774e55..694e0c2bc369 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1041,6 +1041,10 @@ config HAVE_NOINSTR_HACK
 config HAVE_NOINSTR_VALIDATION
 	bool
 
+config HAVE_UACCESS_VALIDATION
+	bool
+	select OBJTOOL
+
 config HAVE_STACK_VALIDATION
 	bool
 	help
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f1320d9a3da3..1a207a805102 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -257,6 +257,7 @@ config X86
 	select HAVE_PREEMPT_DYNAMIC_CALL
 	select HAVE_RSEQ
 	select HAVE_SYSCALL_TRACEPOINTS
+	select HAVE_UACCESS_VALIDATION		if HAVE_OBJTOOL
 	select HAVE_UNSTABLE_SCHED_CLOCK
 	select HAVE_USER_RETURN_NOTIFIER
 	select HAVE_GENERIC_VDSO
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index f89d3fcff39f..de0d88f32f58 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -236,7 +236,7 @@ objtool_args =								\
 	$(if $(CONFIG_SLS), --sls)					\
 	$(if $(CONFIG_STACK_VALIDATION), --stackval)			\
 	$(if $(CONFIG_HAVE_STATIC_CALL_INLINE), --static-call)		\
-	--uaccess							\
+	$(if $(CONFIG_HAVE_UACCESS_VALIDATION), --uaccess)		\
 	$(if $(linked-object), --link)					\
 	$(if $(part-of-module), --module)				\
 	$(if $(CONFIG_GCOV_KERNEL), --no-unreachable)
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index d7f26f02f142..3e23a1babad4 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -153,7 +153,9 @@ objtool_link()
 			objtoolopt="${objtoolopt} --static-call"
 		fi
 
-		objtoolopt="${objtoolopt} --uaccess"
+		if is_enabled CONFIG_HAVE_UACCESS_VALIDATION; then
+			objtoolopt="${objtoolopt} --uaccess"
+		fi
 	fi
 
 	if is_enabled CONFIG_NOINSTR_VALIDATION; then
-- 
2.34.1