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From:   Julien Thierry <jthierry@redhat.com>
To:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc:     catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com,
        ardb@kernel.org, masahiroy@kernel.org, jpoimboe@redhat.com,
        peterz@infradead.org, ycote@redhat.com,
        Raphael Gault <raphael.gault@arm.com>,
        Julien Thierry <jthierry@redhat.com>
Subject: [RFC PATCH v2 13/13] objtool: arm64: Enable stack validation for arm64
Date:   Wed,  3 Mar 2021 18:09:32 +0100
Message-Id: <20210303170932.1838634-14-jthierry@redhat.com>
In-Reply-To: <20210303170932.1838634-1-jthierry@redhat.com>
References: <20210303170932.1838634-1-jthierry@redhat.com>
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From: Raphael Gault <raphael.gault@arm.com>

Add build option to run stack validation at compile time.

When requiring stack validation, jump tables are disabled as it
simplifies objtool analysis (without having to introduce unreliable
artifacs). In local testing, this does not appear to significaly
affect final binary size nor system performance.

Signed-off-by: Raphael Gault <raphael.gault@arm.com>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
---
 arch/arm64/Kconfig  | 1 +
 arch/arm64/Makefile | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 1f212b47a48a..928323c03318 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -187,6 +187,7 @@ config ARM64
 	select MMU_GATHER_RCU_TABLE_FREE
 	select HAVE_RSEQ
 	select HAVE_STACKPROTECTOR
+	select HAVE_STACK_VALIDATION
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 5b84aec31ed3..b819fb2e8eda 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -136,6 +136,10 @@ ifeq ($(CONFIG_DYNAMIC_FTRACE_WITH_REGS),y)
   CC_FLAGS_FTRACE := -fpatchable-function-entry=2
 endif
 
+ifeq ($(CONFIG_STACK_VALIDATION),y)
+KBUILD_CFLAGS	+= -fno-jump-tables
+endif
+
 # Default value
 head-y		:= arch/arm64/kernel/head.o
 
-- 
2.25.4