linux-kernel - [PATCH] x86/build: Disable CET instrumentation in the kernel for 32-bit too

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Date:   Mon, 8 Feb 2021 17:25:43 +0100
From:   Borislav Petkov <bp@...e.de>
To:     AC <achirvasub@...il.com>
Cc:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Marco Elver <elver@...gle.com>, Arnd Bergmann <arnd@...db.de>,
        linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
        kasan-dev@...glegroups.com, jpoimboe@...hat.com, nborisov@...e.com,
        seth.forshee@...onical.com, yamada.masahiro@...ionext.com
Subject: [PATCH] x86/build: Disable CET instrumentation in the kernel for
 32-bit too

On Mon, Feb 08, 2021 at 10:19:33AM -0500, AC wrote:
> That did fix it, thank you!

Thanks!

---
From: Borislav Petkov <bp@...e.de>
Date: Mon, 8 Feb 2021 16:43:30 +0100
Subject: [PATCH] x86/build: Disable CET instrumentation in the kernel for 32-bit too

Commit

  20bf2b378729 ("x86/build: Disable CET instrumentation in the kernel")

disabled CET instrumentation which gets added by default by the Ubuntu
gcc9 and 10 by default, but did that only for 64-bit builds. It would
still fail when building a 32-bit target. So disable CET for all x86
builds.

Fixes: 20bf2b378729 ("x86/build: Disable CET instrumentation in the kernel")
Reported-by: AC <achirvasub@...il.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Tested-by: AC <achirvasub@...il.com>
Link: https://lkml.kernel.org/r/YCCIgMHkzh/xT4ex@arch-chirva.localdomain
---
 arch/x86/Makefile | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 109c7f86483c..b9f58b8993b3 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -50,6 +50,9 @@ export BITS
 KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow
 KBUILD_CFLAGS += $(call cc-option,-mno-avx,)
 
+# Intel CET isn't enabled in the kernel
+KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
+
 ifeq ($(CONFIG_X86_32),y)
         BITS := 32
         UTS_MACHINE := i386
@@ -120,9 +123,6 @@ else
 
         KBUILD_CFLAGS += -mno-red-zone
         KBUILD_CFLAGS += -mcmodel=kernel
-
-	# Intel CET isn't enabled in the kernel
-	KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
 endif
 
 ifdef CONFIG_X86_X32
-- 
2.29.2

-- 
Regards/Gruss,
    Boris.

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