Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Alistair Strachan <astrachan@google.com>,
        Stefan Agner <stefan@agner.ch>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Nick Desaulniers <ndesaulniers@google.com>
Subject: [PATCH 4.19 002/110] efi/libstub: arm: support building with clang
Date:   Thu, 29 Nov 2018 15:11:33 +0100
Message-Id: <20181129135921.329381738@linuxfoundation.org>
In-Reply-To: <20181129135921.231283053@linuxfoundation.org>
References: <20181129135921.231283053@linuxfoundation.org>
User-Agent: quilt/0.65
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alistair Strachan <astrachan@google.com>

commit 41f1c48420709470c51ee0e54b6fb28b956bb4e0 upstream.

When building with CONFIG_EFI and CONFIG_EFI_STUB on ARM, the libstub
Makefile would use -mno-single-pic-base without checking it was
supported by the compiler. As the ARM (32-bit) clang backend does not
support this flag, the build would fail.

This changes the Makefile to check the compiler's support for
-mno-single-pic-base before using it, similar to c1c386681bd7 ("ARM:
8767/1: add support for building ARM kernel with clang").

Signed-off-by: Alistair Strachan <astrachan@google.com>
Reviewed-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/firmware/efi/libstub/Makefile |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -16,7 +16,8 @@ cflags-$(CONFIG_X86)		+= -m$(BITS) -D__K
 cflags-$(CONFIG_ARM64)		:= $(subst -pg,,$(KBUILD_CFLAGS)) -fpie \
 				   $(DISABLE_STACKLEAK_PLUGIN)
 cflags-$(CONFIG_ARM)		:= $(subst -pg,,$(KBUILD_CFLAGS)) \
-				   -fno-builtin -fpic -mno-single-pic-base
+				   -fno-builtin -fpic \
+				   $(call cc-option,-mno-single-pic-base)
 
 cflags-$(CONFIG_EFI_ARMSTUB)	+= -I$(srctree)/scripts/dtc/libfdt